• Journal of Biomedical Engineering Research
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• v.36 no.3
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• pp.69-78
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• 2015

Ultrasonic physiotherapy systems should comply with IEC 60601-2-5(particular requirements for safety of ultrasonic physiotherapy equipment) standard for safety of patients and clinical performances. One of the most important parameters in the standard is the effective radiating area ($A_{ER}$). It has to be measured in accordance with IEC 61689 (field specifications and methods of measurement in the frequency range 0.5MHz to 5MHz). Typical ultrasonic physiotherapy system works in the frequency range 1MHz ~ 3MHz to comply with the IEC 61689. However, ultrasonic physiotherapy system using frequencies over 5MHz is out of the IEC 61689's scope. That is, even if such ultrasonic physiotherapy systems are developed by demands of the market, there is no standard to apply. It is the motivation for this study. Whereas there are other parameters to be considered, this study focuses on the effective radiating area and shows effectiveness of applying IEC 61689 in measuring effective radiating area of ultrasonic physiotherapy systems using frequency range over 5MHz by comparing the results of computer simulation and experiment. Results of this study shows that applying the IEC 61689 standard to ultrasonic physiotherapy system using frequency range over 5MHz is possible.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.9 no.1
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• pp.25-30
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• 2013

The periodic inspection of piping and pressure vessels welds in nuclear power plant has to provide reliable result related to weld flaws, such as location, maximum amplitude response, ultrasonic length, height and finally the nature or flaw pattern. The founded flaw in ultrasonic inspection is accepted or rejected based on these data. Specially, the amplitude of flaw response is used as basic parameter for flaw sizing and it may cause some deviation in length sizing result. Currently the ultrasonic inspections in nuclear power plant components are performed by specific inspection procedure which describing inspection technique include inspection system, calibration methodology and flaw characterizing. To perform ultrasonic inspection during in-service inspection, reference gain should be established before starting ultrasonic inspection by the requirement of ASME code. This reference gain used as basic criteria to evaluate flaw sizing. Sometimes, a little difference in establishing reference gain between calibration and field condition can lead to deviation in flaw sizing. Due to this difference, the inspection result may cause flaw sizing error. Therefore, the objective of this study is to compare and evaluate the ultrasonic amplitude difference between air filled and water filled pipe in nuclear power plant. Additionally, the accuracy of flaw sizing is estimated by comparing both conditions.

• Journal of Korea Multimedia Society
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• v.20 no.10
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• pp.1662-1670
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• 2017

A-Scan NDT equipment is widely used in the industrial field because it is inexpensive and easy to carry but it is necessary to have a skilled inspection specialist who is trained to analyze the waveform of ultrasonic signal. Since the welding quality is judged subjectively by the specialist, there is a problem in the reliability of the quality. In the C-Scan NDT which overcomes the shortcomings of the A-Scan, welding part can be represented in the form of two dimensional image by combining one dimensional ultrasonic waveform so that the quality of welding can be grasped without the help of specialist. In order to develop C-Scan NDT, it is necessary to develop an array type two dimensional transducer and an algorithm to composing image by combining ultrasonic signals generated from a two dimensional transducer. In addition, the noise component must be minimized in the ultrasonic signal in order to display the quality of welding in the form of images. Therefore we propose a method to remove noise component from the ultrasonic wave and construct a two dimensional ultrasonic image.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.2
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• pp.22-28
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• 1993

In this paper, the ultrasonic transducer with a spherical liquid lens is designed and an efficient method to calculate the acoustic field radiated from the transducer is presented. A prototype ultrasonic transducer with a spherical liquid lens is constructed and tested. The experimental results are compared with those of the computer simulations and good agreements are achieved. The dynamic control of the geometric focus is obtained by adjusting the radius of curvature of the lens membrane with the volumetric control of the liquid in the lens.

• Journal of the Korean Society for Nondestructive Testing
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• v.10 no.2
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• pp.43-49
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• 1990

Ultrasonic testing is one of the most useful NDT method for detection of microdefect in the opaque materials. Recently, many applications of the ultrasonic techniques have been extended widely in the new field like electron is and advanced materials. From the result of the experiment, we have hardly found out a crack in the internal parts of the resin and a delamination between chip and resin because of poor performance of the system.

• Journal of the Korea Society of Computer and Information
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• v.7 no.1
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• pp.80-87
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• 2002

In this papers, It was researched Automatic frequency detection which need using ultrasonic utmost effort. As far as ultrasonic Automatic frequency detection, It was analog method, In more dedicated field, to solve a limit. It was needed a new method detection instrument.

• Journal of the Korean Society of Combustion
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• v.8 no.2
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• pp.41-49
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• 2003

Ultrasonic field of 28kHz with sound pressure level 162dB has been employed to agglomerate the fine soot particle produces in a diffusion flame in a chamber. The agglomeration process has been investigated with digital camcorder and analysed in terms of the decrease of number density with exposure time. From the observation of agglomeration process, the initial agglomeration has been carried out during the short time, and it has been dominated by the orthokinetic collision. Thereafter, a slower agglomeration mechanism, driven by acoustic streaming in the chamber takes over and agglomeraters grew to diameters of several millimeters were levitated at the pressure node of the acoustic wave. And, the circular disk shape of large agglomeraters with the rotational and translational motion is observed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.12
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• pp.1200-1209
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• 2010

The main subject of this paper is to develop analytic method with which output power or sensitivity variations of a magnetostrictive ultrasonic transducer can be estimated with no aid of experiments. After the bias magnetic field deployed over the patch is calculated using finite element analysis for magnetostatics, the representative value is extracted by averaging these field values. The operating point on the characteristic curve for magnetostriction is identified by this value and then the output performance is calculated from it. It is verified that the results from this simple model match well with those of its experimental version and some limits of this modeling technique are also considered.

• Journal of Sensor Science and Technology
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• v.10 no.5
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• pp.320-328
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• 2001

Two-dimensional array hydrophones with $8{\times}8$ elements were designed and fabricated using the PVDF(Polyvinylidene fluoride) piezoelectric film, and the method and system for ultrasonic field measurement in several MHz $\sim$ tens of MHz band using the hydrophones was established. The characteristics of frequency response relating to the backing materials were analyzed with the Mason equivalent circuit for design, and the accuracy of ultrasonic field measurement relating to the sizes and kerfs of piezoelectric elements was discussed. Good results of the measurement of ultrasonic field formed by a circular plane transducer of 2.25MHz in water were obtained by the system with the array hydrophones.

• Journal of the Korean Society for Precision Engineering
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• v.4 no.1
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• pp.65-73
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• 1987

In recent days, the application of ultrasonics has been increased in the field of engineering and medicine. The ultrasonic hardness tester to apply the principle of contact compliance method is entirely different from hardness tester in the past and in the practical use, the more pre- cisive measurement is required because it has a slight change of hardness value due to the difference of resonance frequency. Therefore, in this study, as one type of applicative transducers which can detect the optimum pressure load, ring type load cell was used in the measurement of ultrasonic hardness. From experimental results, it was compared ultrasonic hardness testing method with the other hardness testing methods. Also, the measurement error of ultrasonic hardness tester could be measured within .+-. 0.5 HRC F.S. in the case of 3.0Kg pressure load.