WO2009066805A1 - Apparatus and method for measuring ultrasound power by using latent heat - Google Patents

Apparatus and method for measuring ultrasound power by using latent heat Download PDF

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Publication number
WO2009066805A1
WO2009066805A1 PCT/KR2007/005875 KR2007005875W WO2009066805A1 WO 2009066805 A1 WO2009066805 A1 WO 2009066805A1 KR 2007005875 W KR2007005875 W KR 2007005875W WO 2009066805 A1 WO2009066805 A1 WO 2009066805A1
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WIPO (PCT)
Prior art keywords
water
ice
weight
insulation chamber
mixing container
Prior art date
Application number
PCT/KR2007/005875
Other languages
French (fr)
Inventor
Yong Tae Kim
Ho Chul Kim
Sung Soo Jung
Yong Gyoo Kim
Original Assignee
Korea Research Institute Of Standards And Science
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Application filed by Korea Research Institute Of Standards And Science filed Critical Korea Research Institute Of Standards And Science
Priority to PCT/KR2007/005875 priority Critical patent/WO2009066805A1/en
Publication of WO2009066805A1 publication Critical patent/WO2009066805A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D21/00—Measuring or testing not otherwise provided for
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/025—Change of phase or condition
    • G01N2291/0252—Melting, molten solids

Definitions

  • the present invention relates to an apparatus and method for measuring ultrasound power by using latent heat, and more particularly, to an apparatus and method for simply determining ultrasound power by submerging ice in water and then measuring a net weight of the water generated through a melting process in which an ultrasonic wave is sonicated to a certain amount of ice-water mixture.
  • a radiation force balance method In order to measure the ultrasound power, a radiation force balance method, a planar scanning method, a calorimetric method, or the like has been conventionally used.
  • a target used in the measuring process may be damaged when it is exposed to the ultrasonic wave which has the power of higher than about 2OW.
  • the radiation force balance method cannot be used to measure the ultrasound power not smaller than about 2OW.
  • the planar scanning method is to scan the distribution area of the ultrasonic wave by using a hydrophone.
  • the planar scanning method since a large area should be scanned to measure the ultrasound power, the planar scanning method has a problem in that it take a lot of time to measure the ultrasound power.
  • the conventional calorimetric method is to measure water temperature which may be increased due to the ultrasonic wave.
  • a spatial distribution of acoustic pressure in water is not uniform, a plurality of thermometers should be used to measure the water temperature in a plurality of locations.
  • the conventional calorimetric method has problems in that a measuring process is so complicated and it takes a lot of time to install the thermometers and to correct the effects cause by many thermometer heat loss.
  • An object of the present invention is to provide an apparatus and method for measuring ultrasound power in which the net weight of water generated through a process in which ice is melted and changed into water is measured and thus the ultrasound power can be simply determined by using the measured weight change of the water and the specific latent heat of the water.
  • an apparatus for measuring ultrasound power which comprises an ultrasonic transducer for receiving an electrical signal and transducing the electrical signal to an ultrasonic wave; an electrical signal generation unit for supplying the ultrasonic transducer with the electrical signal; a mount capable of moving upward and downward, the ultrasonic transducer being fixed to the mount; a mixing container having an open upper face to receive the ultrasonic transducer therein and detachably fastened to the mount, the mixing container being formed with a plurality of drain holes; a pail-shaped insulation chamber having an open upper face to receive the mixing container therein; and an electronic scale for measuring the weight of water contained in the insulation chamber.
  • the electrical signal generation unit may include a signal generator for generating the electrical signal; and an electric power amplifier for receiving the electrical signal generated from the signal generator, amplifying the received electrical signal and outputting the amplified electrical signal.
  • the mount may include a flange and a fastening tube formed to communicate with the flange, and the ultrasonic transducer is fixed to the fastening tube while an outer peripheral surface of the ultrasonic transducer is spaced apart from an inner peripheral surface of the fastening tube.
  • the flange is formed with a stepped wall having a coupling pin formed thereon, and the mixing container is formed with a coupling hole into which the coupling pin is inserted so that the mixing container is detachably fastened to the flange.
  • the apparatus further comprises a position adjustment unit for adjusting a relative distance between the mount and the electronic scale so that the mixing container is received into the insulation chamber when the mixing container moves downward.
  • the present invention provides a method for measuring ultrasound power in which an insulation chamber and a mixing container from which water is easily discharged are used to mix water with ice, an ultrasonic wave is applied to melt the ice, the weight of the water generated by melting the ice is measured thereby measuring power of the applied ultrasonic wave.
  • the method comprises the steps of: (a) putting the water and the ice in the insulation chamber and the mixing container, respectively; (b) measuring the weight of the water contained in the insulation chamber; (c) mixing the waver with the ice by introducing the water contained in the insulation chamber into the mixing container; (d) applying the ultrasonic wave while the ultrasonic transducer is submerged in the water, thereby melting the ice mixed with the water; (e) discharging the water introduced into the mixing chamber to separate the ice from the water and measuring the weight of the water remaining in the insulation chamber; and (f) subtracting the weight of the water measured in the step (b) from the weight of the water measured in the step (e) to calculate a weight difference therebetween, and calculating the ultrasound power using the calculated weight difference.
  • the ultrasound power be calculated using an equation as follows:
  • P ultrasound power
  • I f specific latent heat while the water is transformed into the ice
  • ⁇ m is a weight change of the water generated by the melting of the ice
  • qc is a change rate, with respect to time, of heat introduced from the outside through the insulation chamber
  • (t 2 -tj) is a time interval during which the ice is mixed with the water
  • ⁇ is an acousto-thermal conversion factor
  • (t off -t on ) is a time interval during which the ultrasonic wave is applied
  • P ca i is ultrasound power calculated by a radiation force balance method.
  • qc is measured by a process including the steps of: (g) putting the water and the ice in the insulation chamber and the mixing container, respectively; (h) measuring the weight of the water contained in the insulation chamber; (i) mixing the water with the ice by introducing the water contained in the insulation chamber into the mixing container; (j) melting the ice during a predetermined time interval; (k) discharging the water introduced into the mixing chamber to separate the ice from the water and measuring the weight of the water remaining in the insulation chamber; and (1) subtracting the weight of the water measured in the step (h) from the weight of the water measured in
  • step (k) to calculate a weight difference therebetween, and calculating ⁇ c using the calculated weight difference.
  • - is measured by a process including the steps of: (m) putting the water and the ice in the insulation chamber and the mixing container, respectively; (n) measuring the weight of the water contained in the insulation chamber; (o) mixing the water with the ice by introducing the water contained in the insulation chamber into the mixing container; (p) applying the ultrasonic wave while the ultrasonic transducer is submerged in the water, thereby melting the ice mixed with the water; (q) discharging the water introduced into the mixing chamber to separate the ice from the water and measuring the weight of the water remaining in the insulation chamber; and (r) subtracting the weight of the water measured in the step (n) from the weight of the water measured in the step (q)
  • the temperature of the water in the step of mixing the water with the ice be not greater than 4 0 C.
  • the weight of water generated through a process in which ice is melted and changed into water is measured and thus the ultrasound power can be simply measured by using the measured weight of the water and the specific latent heat of the water.
  • Fig. 1 is a view illustrating a configuration of an apparatus for measuring ultrasound power according to the present invention.
  • Fig. 2 is a view illustrating a configuration of an electrical signal generation unit.
  • Fig. 3 is a view illustrating a configuration of a heat measurement unit.
  • Fig. 4 is a detailed view illustrating a configuration of a mount.
  • Fig. 5 is a view illustrating a structure of a mixing container.
  • Fig. 6 is a view illustrating a structure of an insulation chamber.
  • Fig. 7 is a view illustrating a configuration of a position adjustment unit.
  • Fig. 8 is a view illustrating a structure of a housing.
  • Fig. 9 is a flowchart of a method for measuring ultrasound power according to the present invention.
  • Fig. 10 is a flowchart of a process of measuring ultrasound power.
  • Fig. 11 is a flowchart of a specific process of measuring ⁇ c .
  • Fig. 12 is a flowchart of a specific process of measuring -.
  • Fig. 13 is a graph showing a weight change of water and a temperature change of
  • Fig. 14 is a graph showing a weight change of water and a temperature change of
  • Fig. 15 is a graph showing a weight change of water and a temperature change of water in the process of measuring ultrasound power P.
  • latent heat is used to measure ultrasonic power.
  • the latent heat means heat to be absorbed or radiated when a material is transferred from a phase to another phase while an equilibrium state of the material is maintained without changing its temperature and pressure.
  • the latent heat required in a process in where ice is melted and changed into water is used, and an ultrasonic wave is used as energy power source to melt the ice.
  • Fig. 1 is a view illustrating a configuration of an apparatus for measuring ultrasonic power according to the present invention, which comprises an electrical signal generation unit 1, a heat measurement unit 2, a position adjustment unit 3, a data acquisition unit 4 and a control unit 5, wherein the heat measurement unit 2 includes an ultrasonic transducer 21 for receiving an electrical signal and transducing the electrical signal into an ultrasonic wave.
  • the heat measurement unit 2 includes an ultrasonic transducer 21 for receiving an electrical signal and transducing the electrical signal into an ultrasonic wave.
  • the electrical signal generation unit 1 is to generate the electrical signal to be applied to the ultrasonic transducer 21, and includes a signal generator 11, an electric power amplifier 12 and a voltmeter 13 as shown in Fig. 2.
  • the electrical signal generated from the signal generator 11 is amplified by the electric power amplifier 12, and the amplified signal is then input into the ultrasonic transducer 21.
  • the operation of the signal generator 11 is controlled by the control unit 5.
  • the control unit 5 may include an external device such as a microcomputer or a computer.
  • the control unit 5 may be configured to supply the signal generator 11 with a voltage-type control signal for determining the frequency or electric power of the electrical signal generated from the signal generator 11.
  • the signal generator 11 be provided with an interface capable of communicating with the control unit 5.
  • the voltmeter 13 is used to measure the voltage of the electrical signal applied to the ultrasonic transducer 21. Since the electrical signal generated from the signal generator 11 is generally an alternating current signal, it is preferable that the voltmeter 13 be an RMS (root mean square) voltmeter.
  • Fig. 3 is a view illustrating a configuration of the heat measurement unit 2, which includes the ultrasonic transducer 21, a mount 22, a mixing container 23, an insulation chamber 24 and an electronic scale 25.
  • the mount 22 is connected to the position adjustment unit 3, so that the position of the mount 22 can be adjusted by means of the position adjustment unit 3.
  • Fig. 4 is a detailed view illustrating the configuration of the mount 22.
  • a melting process of ice 27 by an ultrasonic wave and a weight measurement process of water 26 generated by the melting process of the ice 27 are performed in the heat measurement unit 2.
  • the melting process of the ice 27 is performed by applying the ultrasonic wave while the ice 27 is mixed with the water 26.
  • the water 26 should be separated from the ice 27 in order to measure the weight of the water
  • the water 26 and the ice 27 are separated from each other by respectively putting them in the insulation chamber 24 and the mixing container 23, and while the ultrasonic wave is applied, the water 26 is introduced into the mixing container 23, in which the ice 27 is contained, causing the water 26 and the ice 27 to be mixed with each other.
  • the ultrasonic transducer 21 is to receive the electrical signal generated from the electrical signal generation unit 1 and transduces the electrical signal into the ultrasonic wave, and therefore, generates the ultrasonic wave the power of which will be measured in accordance with the present invention.
  • a resonance-type ultrasonic transducer 21 or the like using a resonance phenomenon of piezoelectric ceramic may be used as the ultrasonic transducer 21.
  • the ultrasonic transducer 21 is fixed to the mount 22 as shown in Fig. 3 or 4, so that the position of the ultrasonic transducer 21 can be adjusted together with the mount 22.
  • the mount 22 includes a fastening tube 41, a flange 42 and an extension tube 43, and is generally made of acryl or aluminum.
  • the fastening tube 41 is a portion to which the ultrasonic transducer 21 is fixed, and is configured to surround an upper portion of the ultrasonic transducer 21. At this time, it is preferable that an outer peripheral surface of the ultrasonic transducer 21 and an inner peripheral surface of the fastening tube 41 be not in close contact with each other but spaced apart from each other because of the characteristics of the ultrasonic transducer 21 which is vibrated while the ultrasonic wave is generated. It is also preferable that the ultrasonic generator be coupled with the fastening tube 41 by means of screws 44. To this end, a plurality of screw holes are formed in a side surface of the fastening tube 41.
  • the screw holes are preferably formed so that they are arranged to be spaced apart at an angle of 120° along the circumference of the fastening tube 41.
  • the extension tube 43 is configured to be capable of receiving wires which are used to supply the ultrasonic transducer 21 with the electrical signal generated from the electrical signal generation unit 1.
  • the extension tube 43 is configured to communicate with one end of the fastening tube 41.
  • the other end of the fastening tube 41 is formed with the flange 42 which communicates with the fastening tube 41.
  • the ultrasonic transducer 21 passes through the flange 42 and is fixed to the fastening tube 41.
  • the flange 42 is fastened to the mixing container 23, which will be described below.
  • Fig. 5 is a view illustrating a structure of the mixing container 23.
  • the mixing container 23 is generally made of acryl or copper, and formed in the shape of a pail with an upper face open.
  • the side and lower surfaces of the mixing container 23 are formed with a plurality of drain holes 28 which allow the water 26 to pass therethrough. Accordingly, when the mixing container 23 is submerged in the water 26 with the ice 27 contained in the mixing container 23, the water 26 is introduced into the mixing container 23 through the drain holes 28, so that the water 26 is mixed with the ice 27.
  • the mixing container 23 generally has a cylindrical shape as shown in Fig. 5, but may be manufactured in various shapes if necessary.
  • thermometer 29 for measuring a temperature change during the process of measuring ultrasound power may be installed within the mixing container 23. At this time, it is preferable that a thermocouple be used as the thermometer 29 and the thermometer 29 be provided with an interface for providing the measured temperature to the data acquisition unit 4 in real time.
  • the mixing container 23 is fastened to the flange 42 of the mount 22 described above, so that the position of the mixing container 23 may be adjusted together with the mount 22.
  • the mixing container 23 is preferably configured to have a horizontal sectional surface larger than that of the ultrasonic transducer 21 so that the mixing container 23 may be fastened to the flange 42 with the ultrasonic transducer 21 received into the mixing container 23.
  • the flange 42 be formed with a stepped wall 45
  • the stepped wall 45 be formed with coupling pins 46
  • the mixing container 23 be formed with coupling holes 47 corresponding in position to the coupling pins 46, thereby inserting and fixing the coupling pins 46 into the coupling holes 47.
  • Fig. 6 is a view illustrating a structure of the insulation chamber 24.
  • the insulation chamber 24 has an open upper face, and is generally made of a thermal insulation material in order to prevent the ice 27 from being melted by the heat introduced from the outside during the process of measuring ultrasound power. Acryl may be used as the thermal insulation material.
  • the mixing container 23 is submerged in the water 26 contained in the insulation chamber 24 during the process of measuring ultrasound power, so that the water 26 can be mixed with the ice 27. Accordingly, it is preferable that the insulation chamber 24 is configured to have a horizontal sectional surface larger than that of the mixing container 23 so that the insulation chamber 24 can accommodate the mixing container 23.
  • the electronic scale 25 is to measure the weight of the water 26 contained in the insulation chamber 24, and a conventional electronic scale with load cells mounted thereon may be used as the electronic scale 25. It is preferable that the electronic scale 25 be provided with an interface through which the measured result in the form of an electrical signal is provided to an external device such as the control unit 5 or the data acquisition unit 4.
  • the data acquisition unit 4 is to obtain data on the temperature and the weight respectively measured from the thermometer 29 and the electronic scale 25, and generally provided with a plurality of input channels through which various kinds of data are input in the form of an electrical signal.
  • the position adjustment unit 3 adjusts the relative position between the mount 22 and the electronic scale 25, so that the mixing container 23 can be received into the insulation chamber 24.
  • Fig. 7 is a view illustrating a configuration of the position adjustment unit 3.
  • the position adjustment unit 3 includes X, Y and Z axial moving stages 51, 52 and 53 which are configured to move the mount 22 or the electronic scale 25 along X, Y and Z axes, respectively; X, Y and Z axis motors 54, 55 and 56 for driving the respective moving stages, and X, Y and Z axis sealers 57, 58 and 59 for respectively providing traveling distances of the mount 22 from the moving stages.
  • the mount 22 is connected to the Z axial moving stage 53 for moving the mount 22 upward and downward, and the X and Y axial moving stages 51 and 52 be configured to adjust the position of the electronic scale 25 on its plane.
  • a controller 60 provides electrical signals for driving the X, Y and Z axis motors 54, 55 and 56 to the respective motors.
  • the position adjustment unit 3 preferably includes a display unit 61, which receives the position information on the mount 22 from the sealers and displays the position of the mount 22.
  • the position adjustment unit 3 is used to adjust the position of the mount 22, so that the positions of the ultrasonic transducer 21 and the mixing container 23 may be adjusted. That is, while the ultrasonic wave is applied to the ice 27 mixed with the water
  • the mixing container 23 and the ultrasonic transducer 21 are moved downward, so that the mixing container 23 is submerged in the water 26 contained in the insulation chamber
  • the water 26 as a transmission media is preferably irradiated with an ultrasonic wave.
  • the control unit 5 controls the duration time and the power of the ultrasonic wave generated from the ultrasonic generator and the position adjustment unit 3, and receives the data measured from the thermometer 29 and the voltmeter 13 directly or through the data acquisition unit 4, and then, the received data may be recorded and analyzed.
  • the control unit 5 means a conventional computer or the like.
  • the mixing container 23 and the insulation chamber 24 as described above be arranged within a housing 30 shown in Fig. 8 in order to block the heat introduced from the outside.
  • the housing 30 is generally made of glass or aluminum, and a door 62 which is opened and closed in a sliding manner for convenience in an experimental process is preferably formed in a side surface of the housing 30. An upper face of the housing 30 is open so that the mixing container 23 can be moved upward and downward.
  • a process of measuring ultrasound power using the apparatus for measuring ultrasound power will be described in detail.
  • Fig. 9 is a flowchart of the method for measuring ultrasound power according to the present invention. As shown in Fig. 9, the process of measuring ultrasound power
  • step SIl of measuring a compensation ⁇ c for influence of heat introduced y from the outside
  • step S 12 of measuring an acousto-thermal conversion factor ⁇
  • the step S 13 of measuring ultrasound power The measured ⁇ c and - are used at the step Sl 3 of measuring ultrasound power.
  • Fig. 10 is a specific flowchart showing the process of measuring ultrasound power, wherein the ultrasound power is represented by Equation 1 as follows:
  • the step S13 of measuring ultrasound power includes the step S21 of measuring weight of the insulation chamber 24 which is vacant and adjusting the zero point of the scale, the step S22 of respectively putting the water 26 and the ice 27 in the insulation chamber 24 and the mixing container 23 and measuring the weight of the water 26 contained in the insulation chamber 24, the step S23 of mixing the ice 27 with the water 26, the step S24 of melting the ice 27 by applying the ultrasonic wave thereto, the step S25 of separating the water 26 from the ice 27 and measuring the weight of the water 26 generated by the melting result of the ice 27, and the step S26 of calculating ultrasound power using the measured weight of the water 26.
  • the step S21 of measuring the weight of the insulation chamber 24 and adjusting the zero point of the scale is the step of putting the vacant insulation chamber 24 on the scale and setting a state where the insulation chamber 24 is put on the scale to be 0 g.
  • the water 26 and the ice 27 are respectively contained in the insulation chamber 24 and the mixing container 23, and the weight of the water 26 contained in the insulation chamber 24 is then detected
  • Equation 1 ti means the time from which the weight of the water 26 contained in the insulation chamber 24 is measured and m(tj) means the weight of the water 26 measured at ti. Then, if the position adjustment unit 3 is used to move the mixing container 23 downward and the mixing container 23 is submerged in the water 26 contained in the insulation chamber 24, the water 26 is introduced into the mixing container 23 through the drain holes 28 formed in the side and bottom surfaces of the mixing container 23, so that the water 26 is mixed with the ice 27 (S23). At this time, in order to prevent the ice 27 from being quickly melted due to the temperature difference between the water 26 and the ice 27, it is preferable that the temperature of the water 26 be adjusted to be not greater than 4 0 C.
  • the ultrasonic wave is applied to melt the ice 27 during a predetermined time interval (S24). At this time, the ultrasonic transducer 21 is sufficiently submerged in the water 26 which is mixed with the ice 27.
  • t o n is the turn-on time of the ultrasound generator and t Off is the turn-off time of the ultrasound generator.
  • the position adjustment unit 3 is used to move the mixing container 23 upward. At this time, the water 26 which has been introduced into the mixing container 23 is discharged through the drain holes 28, so that the ice 27 is separated from the water 26.
  • Equation 1 t 2 means the time just after the ice 27 is separated from the water 26 and m(t 2 ) means the weight of the water 26 measured at the time t 2 .
  • Equation 1 S26
  • q° is a change rate, with respect to time, of heat introduced from the insulation chamber 24 or the outside, has a unit of [J/sec], and is represented by Equation 2. Since the ice 27 is melted by the heat which is inherent in the insulation chamber 24, the heat introduced from the outside through the insulation chamber 24, and the like, a measuring error may be generated. Accordingly, qc is used to compensate the error.
  • the step SI l of measuring ⁇ c comprises the step S31 of measuring the weight of the insulation chamber 24 which is vacant and adjusting the zero point of the scale, the step S32 of respectively putting the water 26 and the ice 27 in the insulation chamber 24 and the mixing container 23 and measuring the weight of the water 26 contained in the insulation chamber 24, the step S33 of mixing the ice 27 with the water 26, the step S34 of melting the ice 27 during a predetermined time interval, the step S35 of separating the water 26 from the ice 27 and measuring the weight of the water 26 generated from the melting result of the ice 27, and the step S36 of calculating ⁇ c using the measured weight of the water 26.
  • the step SI l of measuring qc is substantially identical with the step S13 of measuring ultrasound power except that the ice 27 is melted, without applying ultrasonic wave, by the heat which is inherent in the insulation chamber 24 or the heat which is introduced from the outside.
  • the temperature of the water 26 be adjusted to be not greater than 4 0 C.
  • Fig. 13 is a graph showing a weight change and a temperature change of the water 26 which are measured while the ice 27 is mixed with the water 26 during the time interval
  • ⁇ means an acousto-thermal conversion factor and is represented by as follows:
  • step S 12 of measuring - is identical with the step (S 13)
  • P ca i is the power value of a reference ultrasonic wave source which is calibrated by a radiation force balance method with respect to the reference ultrasonic wave source
  • Fig. 14 is a graph showing a weight change and a temperature change of the water
  • the compensation of the measuring error using q ° is accomplished in the method for measuring ultrasound power.
  • the weight change ⁇ m of the water 26 is 11.73g while the power P of the ultrasonic wave measured by the method for measuring ultrasound power according to the present invention is 0.2065 [J/sec]. Since the power P ca i of the same ultrasonic wave calculated using the radiation force balance method is 0.2112[J/sec], the power P ca i is different from the ultrasound power measured by the present method by about 3%.
  • the weight of water generated through a process in which ice is melted and changed into water is measured and thus the ultrasound power can be simply measured by using the measured weight of the water and the specific latent heat of the water.

Abstract

The present invention relates to an apparatus and method for measuring ultrasound power using latent heat, and more particularly, to an apparatus and method for simply measuring ultrasound power in which the net weight of water generated through a process in which ice is melted and changed into water is measured and thus the ultrasound power can be simply measured by using the measured weight of the water and the specific latent heat of the water. To this end, the present invention provides an apparatus for measuring ultrasound power, which comprises an ultrasonic transducer for receiving an electrical signal and transducing the electrical signal to an ultrasonic wave; an electrical signal generation unit for supplying the ultrasonic transducer with the electrical signal; a mount capable of moving upward and downward, the ultrasonic transducer being fixed to the mount; a mixing container having an open upper face to receive the ultrasonic transducer therein and detachably fastened to the mount, the mixing container being formed with a plurality of drain holes; a pail-shaped insulation chamber having an open upper face to receive the mixing container therein; and an electronic scale for measuring the weight of water contained in the insulation chamber.

Description

[DESCRIPTION] [Invention Title]
APPARATUS AND METHOD FOR MEASURING ULTRASOUND POWER BY USING LATENT HEAT
[Technical Field]
The present invention relates to an apparatus and method for measuring ultrasound power by using latent heat, and more particularly, to an apparatus and method for simply determining ultrasound power by submerging ice in water and then measuring a net weight of the water generated through a melting process in which an ultrasonic wave is sonicated to a certain amount of ice-water mixture.
[Background Art]
Recently, application areas of an ultrasonic wave has been enlarged to diagnostic imaging apparatuses in medical services, ultrasonic wave cleaning technologies, various facility diagnostic fields, or the like, and therefore, the technologies capable of exactly measuring ultrasound power have been required.
In order to measure the ultrasound power, a radiation force balance method, a planar scanning method, a calorimetric method, or the like has been conventionally used. However, in the case of the radiation force balance method, a target used in the measuring process may be damaged when it is exposed to the ultrasonic wave which has the power of higher than about 2OW. Thus, the radiation force balance method cannot be used to measure the ultrasound power not smaller than about 2OW.
The planar scanning method is to scan the distribution area of the ultrasonic wave by using a hydrophone. However, since a large area should be scanned to measure the ultrasound power, the planar scanning method has a problem in that it take a lot of time to measure the ultrasound power.
The conventional calorimetric method is to measure water temperature which may be increased due to the ultrasonic wave. However, since a spatial distribution of acoustic pressure in water is not uniform, a plurality of thermometers should be used to measure the water temperature in a plurality of locations. Thus, the conventional calorimetric method has problems in that a measuring process is so complicated and it takes a lot of time to install the thermometers and to correct the effects cause by many thermometer heat loss.
[Technical Problem]
Accordingly, the present invention is conceived to solve the aforementioned problems. An object of the present invention is to provide an apparatus and method for measuring ultrasound power in which the net weight of water generated through a process in which ice is melted and changed into water is measured and thus the ultrasound power can be simply determined by using the measured weight change of the water and the specific latent heat of the water.
[Technical Solution]
According to an aspect of the present invention for achieving the objects, there is provided an apparatus for measuring ultrasound power, which comprises an ultrasonic transducer for receiving an electrical signal and transducing the electrical signal to an ultrasonic wave; an electrical signal generation unit for supplying the ultrasonic transducer with the electrical signal; a mount capable of moving upward and downward, the ultrasonic transducer being fixed to the mount; a mixing container having an open upper face to receive the ultrasonic transducer therein and detachably fastened to the mount, the mixing container being formed with a plurality of drain holes; a pail-shaped insulation chamber having an open upper face to receive the mixing container therein; and an electronic scale for measuring the weight of water contained in the insulation chamber.
The electrical signal generation unit may include a signal generator for generating the electrical signal; and an electric power amplifier for receiving the electrical signal generated from the signal generator, amplifying the received electrical signal and outputting the amplified electrical signal.
The mount may include a flange and a fastening tube formed to communicate with the flange, and the ultrasonic transducer is fixed to the fastening tube while an outer peripheral surface of the ultrasonic transducer is spaced apart from an inner peripheral surface of the fastening tube.
Preferably, the flange is formed with a stepped wall having a coupling pin formed thereon, and the mixing container is formed with a coupling hole into which the coupling pin is inserted so that the mixing container is detachably fastened to the flange. Preferably, the apparatus further comprises a position adjustment unit for adjusting a relative distance between the mount and the electronic scale so that the mixing container is received into the insulation chamber when the mixing container moves downward.
The present invention provides a method for measuring ultrasound power in which an insulation chamber and a mixing container from which water is easily discharged are used to mix water with ice, an ultrasonic wave is applied to melt the ice, the weight of the water generated by melting the ice is measured thereby measuring power of the applied ultrasonic wave. The method comprises the steps of: (a) putting the water and the ice in the insulation chamber and the mixing container, respectively; (b) measuring the weight of the water contained in the insulation chamber; (c) mixing the waver with the ice by introducing the water contained in the insulation chamber into the mixing container; (d) applying the ultrasonic wave while the ultrasonic transducer is submerged in the water, thereby melting the ice mixed with the water; (e) discharging the water introduced into the mixing chamber to separate the ice from the water and measuring the weight of the water remaining in the insulation chamber; and (f) subtracting the weight of the water measured in the step (b) from the weight of the water measured in the step (e) to calculate a weight difference therebetween, and calculating the ultrasound power using the calculated weight difference.
It is preferable that the ultrasound power be calculated using an equation as follows:
lf ' Am - qc ' ( /2 - Z1 )
P = ζ * ( toff" ton ) wherein, q° and - may be represented by equations as follows:
V Am q<
U - tΛ
Figure imgf000006_0001
wherein, P is ultrasound power, If is specific latent heat while the water is transformed into the ice, Δm is a weight change of the water generated by the melting of the ice, qc is a change rate, with respect to time, of heat introduced from the outside through the insulation chamber, (t2-tj) is a time interval during which the ice is mixed with the water, ζ is an acousto-thermal conversion factor, (toff-ton) is a time interval during which the ultrasonic wave is applied, and Pcai is ultrasound power calculated by a radiation force balance method.
Preferably, qc is measured by a process including the steps of: (g) putting the water and the ice in the insulation chamber and the mixing container, respectively; (h) measuring the weight of the water contained in the insulation chamber; (i) mixing the water with the ice by introducing the water contained in the insulation chamber into the mixing container; (j) melting the ice during a predetermined time interval; (k) discharging the water introduced into the mixing chamber to separate the ice from the water and measuring the weight of the water remaining in the insulation chamber; and (1) subtracting the weight of the water measured in the step (h) from the weight of the water measured in
the step (k) to calculate a weight difference therebetween, and calculating ^c using the calculated weight difference.
Preferably, - is measured by a process including the steps of: (m) putting the water and the ice in the insulation chamber and the mixing container, respectively; (n) measuring the weight of the water contained in the insulation chamber; (o) mixing the water with the ice by introducing the water contained in the insulation chamber into the mixing container; (p) applying the ultrasonic wave while the ultrasonic transducer is submerged in the water, thereby melting the ice mixed with the water; (q) discharging the water introduced into the mixing chamber to separate the ice from the water and measuring the weight of the water remaining in the insulation chamber; and (r) subtracting the weight of the water measured in the step (n) from the weight of the water measured in the step (q)
to calculate a weight difference therebetween, and calculating - using the calculated weight difference. It is preferable that the temperature of the water in the step of mixing the water with the ice be not greater than 40C.
[Advantageous Effects]
According to an apparatus and method for measuring ultrasound power in accordance with the present invention, the weight of water generated through a process in which ice is melted and changed into water is measured and thus the ultrasound power can be simply measured by using the measured weight of the water and the specific latent heat of the water.
[Description of Drawings]
Fig. 1 is a view illustrating a configuration of an apparatus for measuring ultrasound power according to the present invention.
Fig. 2 is a view illustrating a configuration of an electrical signal generation unit.
Fig. 3 is a view illustrating a configuration of a heat measurement unit. Fig. 4 is a detailed view illustrating a configuration of a mount.
Fig. 5 is a view illustrating a structure of a mixing container.
Fig. 6 is a view illustrating a structure of an insulation chamber.
Fig. 7 is a view illustrating a configuration of a position adjustment unit.
Fig. 8 is a view illustrating a structure of a housing. Fig. 9 is a flowchart of a method for measuring ultrasound power according to the present invention.
Fig. 10 is a flowchart of a process of measuring ultrasound power.
Fig. 11 is a flowchart of a specific process of measuring ^c.
Fig. 12 is a flowchart of a specific process of measuring -. Fig. 13 is a graph showing a weight change of water and a temperature change of
water in the process of measuring ** c.
Fig. 14 is a graph showing a weight change of water and a temperature change of
water in the process of measuring -.
Fig. 15 is a graph showing a weight change of water and a temperature change of water in the process of measuring ultrasound power P.
[Mode for Invention]
Hereinafter, the present invention will be described in detail. In an apparatus and method for measuring ultrasound power according to the present invention, latent heat is used to measure ultrasonic power.
The latent heat means heat to be absorbed or radiated when a material is transferred from a phase to another phase while an equilibrium state of the material is maintained without changing its temperature and pressure. According to the present invention, the latent heat required in a process in where ice is melted and changed into water is used, and an ultrasonic wave is used as energy power source to melt the ice.
Fig. 1 is a view illustrating a configuration of an apparatus for measuring ultrasonic power according to the present invention, which comprises an electrical signal generation unit 1, a heat measurement unit 2, a position adjustment unit 3, a data acquisition unit 4 and a control unit 5, wherein the heat measurement unit 2 includes an ultrasonic transducer 21 for receiving an electrical signal and transducing the electrical signal into an ultrasonic wave.
The electrical signal generation unit 1 is to generate the electrical signal to be applied to the ultrasonic transducer 21, and includes a signal generator 11, an electric power amplifier 12 and a voltmeter 13 as shown in Fig. 2. The electrical signal generated from the signal generator 11 is amplified by the electric power amplifier 12, and the amplified signal is then input into the ultrasonic transducer 21.
The operation of the signal generator 11 is controlled by the control unit 5. The control unit 5 may include an external device such as a microcomputer or a computer. The control unit 5 may be configured to supply the signal generator 11 with a voltage-type control signal for determining the frequency or electric power of the electrical signal generated from the signal generator 11. To this end, it is preferable that the signal generator 11 be provided with an interface capable of communicating with the control unit 5. The voltmeter 13 is used to measure the voltage of the electrical signal applied to the ultrasonic transducer 21. Since the electrical signal generated from the signal generator 11 is generally an alternating current signal, it is preferable that the voltmeter 13 be an RMS (root mean square) voltmeter. At this time, the voltmeter 13 is preferably provided with an interface for transmitting the measured voltage value to the control unit 5. Fig. 3 is a view illustrating a configuration of the heat measurement unit 2, which includes the ultrasonic transducer 21, a mount 22, a mixing container 23, an insulation chamber 24 and an electronic scale 25. The mount 22 is connected to the position adjustment unit 3, so that the position of the mount 22 can be adjusted by means of the position adjustment unit 3. Fig. 4 is a detailed view illustrating the configuration of the mount 22.
A melting process of ice 27 by an ultrasonic wave and a weight measurement process of water 26 generated by the melting process of the ice 27 are performed in the heat measurement unit 2. At this time, the melting process of the ice 27 is performed by applying the ultrasonic wave while the ice 27 is mixed with the water 26. However, the water 26 should be separated from the ice 27 in order to measure the weight of the water
26 generated by the melting process of the ice 27. Therefore, according to the present invention, the water 26 and the ice 27 are separated from each other by respectively putting them in the insulation chamber 24 and the mixing container 23, and while the ultrasonic wave is applied, the water 26 is introduced into the mixing container 23, in which the ice 27 is contained, causing the water 26 and the ice 27 to be mixed with each other. The ultrasonic transducer 21 is to receive the electrical signal generated from the electrical signal generation unit 1 and transduces the electrical signal into the ultrasonic wave, and therefore, generates the ultrasonic wave the power of which will be measured in accordance with the present invention. A resonance-type ultrasonic transducer 21 or the like using a resonance phenomenon of piezoelectric ceramic may be used as the ultrasonic transducer 21.
The ultrasonic transducer 21 is fixed to the mount 22 as shown in Fig. 3 or 4, so that the position of the ultrasonic transducer 21 can be adjusted together with the mount 22.
As shown in Fig. 4, the mount 22 includes a fastening tube 41, a flange 42 and an extension tube 43, and is generally made of acryl or aluminum.
The fastening tube 41 is a portion to which the ultrasonic transducer 21 is fixed, and is configured to surround an upper portion of the ultrasonic transducer 21. At this time, it is preferable that an outer peripheral surface of the ultrasonic transducer 21 and an inner peripheral surface of the fastening tube 41 be not in close contact with each other but spaced apart from each other because of the characteristics of the ultrasonic transducer 21 which is vibrated while the ultrasonic wave is generated. It is also preferable that the ultrasonic generator be coupled with the fastening tube 41 by means of screws 44. To this end, a plurality of screw holes are formed in a side surface of the fastening tube 41.
The screw holes are preferably formed so that they are arranged to be spaced apart at an angle of 120° along the circumference of the fastening tube 41.
The extension tube 43 is configured to be capable of receiving wires which are used to supply the ultrasonic transducer 21 with the electrical signal generated from the electrical signal generation unit 1. The extension tube 43 is configured to communicate with one end of the fastening tube 41. The other end of the fastening tube 41 is formed with the flange 42 which communicates with the fastening tube 41. The ultrasonic transducer 21 passes through the flange 42 and is fixed to the fastening tube 41. The flange 42 is fastened to the mixing container 23, which will be described below.
Fig. 5 is a view illustrating a structure of the mixing container 23. In the process of measuring ultrasound power, the ice 27 is mixed with the water 26 in the mixing container 23. The mixing container 23 is generally made of acryl or copper, and formed in the shape of a pail with an upper face open. The side and lower surfaces of the mixing container 23 are formed with a plurality of drain holes 28 which allow the water 26 to pass therethrough. Accordingly, when the mixing container 23 is submerged in the water 26 with the ice 27 contained in the mixing container 23, the water 26 is introduced into the mixing container 23 through the drain holes 28, so that the water 26 is mixed with the ice 27. At this time, in order to prevent the ice 27 from passing through the drain holes 28, it is preferable that the diameter of the drain holes 28 be smaller than the size of the ice 27 used in the measuring process. The mixing container 23 generally has a cylindrical shape as shown in Fig. 5, but may be manufactured in various shapes if necessary.
A thermometer 29 for measuring a temperature change during the process of measuring ultrasound power may be installed within the mixing container 23. At this time, it is preferable that a thermocouple be used as the thermometer 29 and the thermometer 29 be provided with an interface for providing the measured temperature to the data acquisition unit 4 in real time.
The mixing container 23 is fastened to the flange 42 of the mount 22 described above, so that the position of the mixing container 23 may be adjusted together with the mount 22. At this time, the mixing container 23 is preferably configured to have a horizontal sectional surface larger than that of the ultrasonic transducer 21 so that the mixing container 23 may be fastened to the flange 42 with the ultrasonic transducer 21 received into the mixing container 23.
Further, in order to quickly fasten or detach the mixing container 23, it is preferable that, as shown in Fig. 4, the flange 42 be formed with a stepped wall 45, the stepped wall 45 be formed with coupling pins 46, and the mixing container 23 be formed with coupling holes 47 corresponding in position to the coupling pins 46, thereby inserting and fixing the coupling pins 46 into the coupling holes 47.
Fig. 6 is a view illustrating a structure of the insulation chamber 24. The insulation chamber 24 has an open upper face, and is generally made of a thermal insulation material in order to prevent the ice 27 from being melted by the heat introduced from the outside during the process of measuring ultrasound power. Acryl may be used as the thermal insulation material. The mixing container 23 is submerged in the water 26 contained in the insulation chamber 24 during the process of measuring ultrasound power, so that the water 26 can be mixed with the ice 27. Accordingly, it is preferable that the insulation chamber 24 is configured to have a horizontal sectional surface larger than that of the mixing container 23 so that the insulation chamber 24 can accommodate the mixing container 23.
The electronic scale 25 is to measure the weight of the water 26 contained in the insulation chamber 24, and a conventional electronic scale with load cells mounted thereon may be used as the electronic scale 25. It is preferable that the electronic scale 25 be provided with an interface through which the measured result in the form of an electrical signal is provided to an external device such as the control unit 5 or the data acquisition unit 4.
The data acquisition unit 4 is to obtain data on the temperature and the weight respectively measured from the thermometer 29 and the electronic scale 25, and generally provided with a plurality of input channels through which various kinds of data are input in the form of an electrical signal.
The position adjustment unit 3 adjusts the relative position between the mount 22 and the electronic scale 25, so that the mixing container 23 can be received into the insulation chamber 24. Fig. 7 is a view illustrating a configuration of the position adjustment unit 3. As shown in Fig. 7, the position adjustment unit 3 includes X, Y and Z axial moving stages 51, 52 and 53 which are configured to move the mount 22 or the electronic scale 25 along X, Y and Z axes, respectively; X, Y and Z axis motors 54, 55 and 56 for driving the respective moving stages, and X, Y and Z axis sealers 57, 58 and 59 for respectively providing traveling distances of the mount 22 from the moving stages. At this time, it is preferable that the mount 22 is connected to the Z axial moving stage 53 for moving the mount 22 upward and downward, and the X and Y axial moving stages 51 and 52 be configured to adjust the position of the electronic scale 25 on its plane. A controller 60 provides electrical signals for driving the X, Y and Z axis motors 54, 55 and 56 to the respective motors. At this time, the position adjustment unit 3 preferably includes a display unit 61, which receives the position information on the mount 22 from the sealers and displays the position of the mount 22.
Since the mount 22 is coupled with the ultrasonic transducer 21 and the mixing container 23, the position adjustment unit 3 is used to adjust the position of the mount 22, so that the positions of the ultrasonic transducer 21 and the mixing container 23 may be adjusted. That is, while the ultrasonic wave is applied to the ice 27 mixed with the water
26, the mixing container 23 and the ultrasonic transducer 21 are moved downward, so that the mixing container 23 is submerged in the water 26 contained in the insulation chamber
24. At this time, a lower portion of the ultrasonic transducer 21, which is not received into the fastening tube 41 but exposed from the mount 22, is also submerged in the water
26, so that the water 26 as a transmission media is preferably irradiated with an ultrasonic wave.
The control unit 5 controls the duration time and the power of the ultrasonic wave generated from the ultrasonic generator and the position adjustment unit 3, and receives the data measured from the thermometer 29 and the voltmeter 13 directly or through the data acquisition unit 4, and then, the received data may be recorded and analyzed. Thus, the control unit 5 means a conventional computer or the like.
It is preferable that the mixing container 23 and the insulation chamber 24 as described above be arranged within a housing 30 shown in Fig. 8 in order to block the heat introduced from the outside. The housing 30 is generally made of glass or aluminum, and a door 62 which is opened and closed in a sliding manner for convenience in an experimental process is preferably formed in a side surface of the housing 30. An upper face of the housing 30 is open so that the mixing container 23 can be moved upward and downward. Hereinafter, a process of measuring ultrasound power using the apparatus for measuring ultrasound power will be described in detail.
Fig. 9 is a flowchart of the method for measuring ultrasound power according to the present invention. As shown in Fig. 9, the process of measuring ultrasound power
comprises the step SIl of measuring a compensation ^c for influence of heat introduced y from the outside, the step S 12 of measuring an acousto-thermal conversion factor \ and
the step S 13 of measuring ultrasound power. The measured ^c and - are used at the step Sl 3 of measuring ultrasound power.
First, the step S13 of measuring ultrasound power will be described with reference to Fig. 10. Fig. 10 is a specific flowchart showing the process of measuring ultrasound power, wherein the ultrasound power is represented by Equation 1 as follows:
[Equation 1]
•
Figure imgf000014_0001
wherein, P is ultrasound power, If is specific latent heat in a process of transforming water into ice, i.e., If = 344J/g, (toff-tOn) is a time interval during which the ultrasonic wave is applied, and (t2-tj) is a time interval during which the ice 27 is mixed with the water 26. Δm is represented by Δm= m(t2)-m(t1), which means a difference between the weight m(t2) of the water 26 measured at time t2 when the ice 27 is separated from the water 26 and the weight m(tθ of the water 26 measured at time i\ just before the ice 27 is mixed with the water 26.
The step S13 of measuring ultrasound power includes the step S21 of measuring weight of the insulation chamber 24 which is vacant and adjusting the zero point of the scale, the step S22 of respectively putting the water 26 and the ice 27 in the insulation chamber 24 and the mixing container 23 and measuring the weight of the water 26 contained in the insulation chamber 24, the step S23 of mixing the ice 27 with the water 26, the step S24 of melting the ice 27 by applying the ultrasonic wave thereto, the step S25 of separating the water 26 from the ice 27 and measuring the weight of the water 26 generated by the melting result of the ice 27, and the step S26 of calculating ultrasound power using the measured weight of the water 26.
The step S21 of measuring the weight of the insulation chamber 24 and adjusting the zero point of the scale is the step of putting the vacant insulation chamber 24 on the scale and setting a state where the insulation chamber 24 is put on the scale to be 0 g.
This is to enhance the accuracy in the weight measurement step since the weight of the water 26 is measured in the step of measuring ultrasound power.
After the zero point adjustment of the scale is completed, the water 26 and the ice 27 are respectively contained in the insulation chamber 24 and the mixing container 23, and the weight of the water 26 contained in the insulation chamber 24 is then detected
(S22). In Equation 1, ti means the time from which the weight of the water 26 contained in the insulation chamber 24 is measured and m(tj) means the weight of the water 26 measured at ti. Then, if the position adjustment unit 3 is used to move the mixing container 23 downward and the mixing container 23 is submerged in the water 26 contained in the insulation chamber 24, the water 26 is introduced into the mixing container 23 through the drain holes 28 formed in the side and bottom surfaces of the mixing container 23, so that the water 26 is mixed with the ice 27 (S23). At this time, in order to prevent the ice 27 from being quickly melted due to the temperature difference between the water 26 and the ice 27, it is preferable that the temperature of the water 26 be adjusted to be not greater than 40C.
If the water 26 is mixed with the ice 27, the ultrasonic wave is applied to melt the ice 27 during a predetermined time interval (S24). At this time, the ultrasonic transducer 21 is sufficiently submerged in the water 26 which is mixed with the ice 27. In Equation
1, ton is the turn-on time of the ultrasound generator and tOff is the turn-off time of the ultrasound generator.
When the melting process of the ice 27 by means of the ultrasonic wave is completed, the position adjustment unit 3 is used to move the mixing container 23 upward. At this time, the water 26 which has been introduced into the mixing container 23 is discharged through the drain holes 28, so that the ice 27 is separated from the water 26.
Then, the weight of the water 26 contained in the insulation chamber 24 is measured (S25).
In Equation 1, t2 means the time just after the ice 27 is separated from the water 26 and m(t2) means the weight of the water 26 measured at the time t2. Finally, the power P of the ultrasonic wave is calculated using Equation 1 (S26). At this time, two measured values q° and ζ are used as shown in Equation 1,
and therefore, the processes of measuring q° and ζ will be described later. Figs. 11
and 12 are flowcharts of specific processes of measuring q° and ^ respectively. q° is a change rate, with respect to time, of heat introduced from the insulation chamber 24 or the outside, has a unit of [J/sec], and is represented by Equation 2. Since the ice 27 is melted by the heat which is inherent in the insulation chamber 24, the heat introduced from the outside through the insulation chamber 24, and the like, a measuring error may be generated. Accordingly, qc is used to compensate the error.
[Equation 2]
Figure imgf000016_0001
The step SI l of measuring ^c comprises the step S31 of measuring the weight of the insulation chamber 24 which is vacant and adjusting the zero point of the scale, the step S32 of respectively putting the water 26 and the ice 27 in the insulation chamber 24 and the mixing container 23 and measuring the weight of the water 26 contained in the insulation chamber 24, the step S33 of mixing the ice 27 with the water 26, the step S34 of melting the ice 27 during a predetermined time interval, the step S35 of separating the water 26 from the ice 27 and measuring the weight of the water 26 generated from the melting result of the ice 27, and the step S36 of calculating ^c using the measured weight of the water 26.
That is, the step SI l of measuring qc is substantially identical with the step S13 of measuring ultrasound power except that the ice 27 is melted, without applying ultrasonic wave, by the heat which is inherent in the insulation chamber 24 or the heat which is introduced from the outside. At this time, in order to prevent the ice 27 from being quickly melted due to the temperature difference between the water 26 and the ice 27, it is preferable that the temperature of the water 26 be adjusted to be not greater than 40C.
Fig. 13 is a graph showing a weight change and a temperature change of the water 26 which are measured while the ice 27 is mixed with the water 26 during the time interval
(t2-ti)=426.188[sec]. The weight change Δm of the water 26 is 3.925g while the calculated compensation value 9« is 3.075 [J/sec].
■ means an acousto-thermal conversion factor and is represented by as follows:
[Equation 3]
Figure imgf000017_0001
As shown in Fig. 12, the step S 12 of measuring - is identical with the step (S 13)
of measuring the ultrasound power except that Pcai is required to calculate ^ as shown in Equation 3.
Pcai is the power value of a reference ultrasonic wave source which is calibrated by a radiation force balance method with respect to the reference ultrasonic wave source,
and is a well-known value. The value ζ measured using Pca) is a constant value which is fixed in a range of uncertainty regarding the apparatus according to the present invention. Fig. 14 is a graph showing a weight change and a temperature change of the water
26 which is measured when (t2-ti)=428.516[sec] and (tOfrton)=200[sec]. The weight r change Δm of the water 26 is 7.943g while the measured -. is 62.79. At this time, a value of Pcai is 0.1063 [J/sec] .
As discussed above, the compensation of the measuring error using q° is accomplished in the method for measuring ultrasound power. However, the shorter are the time interval from the time U at which the water 26 is mixed with the ice 27 to the turn- on time ton from which the ultrasonic wave is applied and the time interval from the turn- off time toff from which the ultrasonic wave is no longer applied to the time t2 at which the ice 27 is separated from the water 26, the more improved is the accuracy of the measuring method.
Fig. 15 is a graph showing a weight change and a temperature change of the water 26 which is measured when (t2-ti)=430.765[sec] and (tOfrtOn)=200[sec]. The weight change Δm of the water 26 is 11.73g while the power P of the ultrasonic wave measured by the method for measuring ultrasound power according to the present invention is 0.2065 [J/sec]. Since the power Pcai of the same ultrasonic wave calculated using the radiation force balance method is 0.2112[J/sec], the power Pcai is different from the ultrasound power measured by the present method by about 3%.
[Industrial Applicability] According to an apparatus and method for measuring ultrasound power according to the present invention, the weight of water generated through a process in which ice is melted and changed into water is measured and thus the ultrasound power can be simply measured by using the measured weight of the water and the specific latent heat of the water.

Claims

[CLAIMS] [Claim 1 ]
An apparatus for measuring ultrasound power, comprising: an ultrasonic transducer for receiving an electrical signal and transducing the electrical signal to an ultrasonic wave; an electrical signal generation unit for supplying the ultrasonic transducer with the electrical signal; a mount capable of moving upward and downward, the ultrasonic transducer being fixed to the mount; a mixing container having an open upper face to receive the ultrasonic transducer therein and detachably fastened to the mount, the mixing container being formed with a plurality of drain holes; a pail-shaped insulation chamber having an open upper face to receive the mixing container therein; and an electronic scale for measuring the weight of water contained in the insulation chamber.
[Claim 2]
The apparatus as claimed in claim 1, wherein the electrical signal generation unit includes a signal generator for generating the electrical signal; and an electric power amplifier for receiving the electrical signal generated from the signal generator, amplifying the received electrical signal and outputting the amplified electrical signal.
[Claim 3] The apparatus as claimed in claim 1, wherein the mount includes a flange and a fastening tube formed to communicate with the flange, and the ultrasonic transducer is fixed to the fastening tube while an outer peripheral surface of the ultrasonic transducer is spaced apart from an inner peripheral surface of the fastening tube.
[Claim 4] The apparatus as claimed in claim 1 , wherein the flange is formed with a stepped wall having a coupling pin formed thereon, and the mixing container is formed with a coupling hole into which the coupling pin is inserted so that the mixing container is detachably fastened to the flange.
[Claim 5]
The apparatus as claimed in claim 1, further comprising a position adjustment unit for adjusting a relative distance between the mount and the electronic scale so that the mixing container is received into the insulation chamber when the mixing container moves downward.
[Claim 6]
A method for measuring ultrasound power in which an insulation chamber and a mixing container from which water is easily discharged are used to mix water with ice, an ultrasonic wave is applied to melt the ice, the weight of the water generated by melting the ice is measured thereby measuring power of the applied ultrasonic wave, the method comprising the steps of:
(a) putting the water and the ice in the insulation chamber and the mixing container, respectively; (b) measuring the weight of the water contained in the insulation chamber;
(c) mixing the waver with the ice by introducing the water contained in the insulation chamber into the mixing container;
(d) applying the ultrasonic wave while the ultrasonic transducer is submerged in the water, thereby melting the ice mixed with the water; (e) discharging the water introduced into the mixing chamber to separate the ice from the water and measuring the weight of the water remaining in the insulation chamber; and
(f) subtracting the weight of the water measured in the step (b) from the weight of the water measured in the step (e) to calculate a weight difference therebetween, and calculating the ultrasound power using the calculated weight difference.
[Claim 7]
The method as claimed in claim 6, wherein the temperature of the water in the step (b) is not greater than 40C.
[Claim 8]
The method as claimed in claim 6 or 7, wherein the ultrasound power in the step (f) is calculated using an equation as follows:
Figure imgf000021_0001
ζ • ( tojgr - ton ) wherein, P is ultrasound power, If is specific latent heat while the water is transformed into the ice, Δm is a weight difference calculated in the step (f), qc is a time rate of change of heat introduced into the insulation chamber from the outside through the insulation chamber, (t2-ti) is an time interval during which the ice is mixed with the water,
- is an acousto-thermal conversion factor, and (toff4on) is an time interval during which the ultrasonic wave is applied.
[Claim 9]
The method as claimed in claim 8, wherein q<: is measured by a process including the steps of: (g) putting the water and the ice in the insulation chamber and the mixing container, respectively;
(h) measuring the weight of the water contained in the insulation chamber; (i) mixing the water with the ice by introducing the water contained in the insulation chamber into the mixing container; (j) melting the ice during a predetermined time interval;
(k) discharging the water introduced into the mixing chamber to separate the ice from the water and measuring the weight of the water remaining in the insulation chamber; 2
and
(1) subtracting the weight of the water measured in the step (h) from the weight of the water measured in the step (k) to calculate a weight difference therebetween, and
calculating ^c using the calculated weight difference.
[Claim 10]
The method as claimed in claim 9, wherein ^c in the step (1) is calculated using an equation as follows:
Figure imgf000022_0001
wherein, If is a specific latent heat while the water is transformed into the ice, Δm is a weight difference calculated in the step (1), and (t2-t0 is a time interval during which the ice is mixed with the water.
[Claim 11 ]
The method as claimed in claim 9, wherein the temperature of the water in the step (h) is not greater than 4°C.
[Claim 12]
The method as claimed in claim 8, wherein ^ is measured by a process including the steps of:
(m) putting the water and the ice in the insulation chamber and the mixing container, respectively;
(n) measuring the weight of the water contained in the insulation chamber; (o) mixing the water with the ice by introducing the water contained in the insulation chamber into the mixing container; (p) applying the ultrasonic wave while the ultrasonic transducer is submerged in the water, thereby melting the ice mixed with the water;
(q) discharging the water introduced into the mixing chamber to separate the ice from the water and measuring the weight of the water remaining in the insulation chamber; and
(r) subtracting the weight of the water measured in the step (n) from the weight of the water measured in the step (q) to calculate a weight difference therebetween, and
<- calculating L* using the calculated weight difference.
[Claim 13]
The method as claimed in claim 12, wherein ^ in the step (r) is calculated using an equation as follows:
= lf - Am - qc ' ( t2 - Z1 )
Figure imgf000023_0001
wherein, If is a specific latent heat while the water is transformed into the ice, Δm
is a weight difference calculated in the step (r), " c is a change rate, with respect to time, of heat introduced from the outside through the insulation chamber, (t2-tj) is a time interval during which the ice is mixed with the water, Pcai is ultrasound power calculated by a radiation force balance method, and (toff-ton) is a time interval during which the ultrasonic wave is applied.
[Claim 14]
The method as claimed in claim 12, wherein the temperature of the water in the step (h) is not greater than 4°C.
PCT/KR2007/005875 2007-11-21 2007-11-21 Apparatus and method for measuring ultrasound power by using latent heat WO2009066805A1 (en)

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RU2610879C1 (en) * 2015-11-27 2017-02-17 федеральное государственное бюджетное образовательное учреждение высшего образования "Национальный исследовательский университет "МЭИ" Method of measuring ultrasonic radiation power

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