• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 학술대회 논문집
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• pp.359-364
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• 2004

This paper deals with the comparison of signal processing techniques of ultrasonic data. The goal of signal processing is the ultrasonic speckle suppression and the visibility enhancement of flaw-reflected ultrasonic echo. The performance of conventional SSP(split spectrum processing) method and the wavelet denoising method are compared and discussed for tested ultrasonic data. Tested ultrasonic data obtained from the weld area of centrifugal-casted stainless steel material and safe-ending material with holes and notch of variable depths are presented. In experimental results, the outputs of wavelet-based denoising method show the clear and sharp peaks at the positions of flaw-reflected echos comparing with those of SSP method.

• Transactions on Electrical and Electronic Materials
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• 제10권5호
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• pp.156-160
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• 2009

In an ultrasonic motor, a piezoelectric ceramic material forms the active element which vibrates the stator, thus initiating the rotational motion. In the operation of ultrasonic motors, many factors exist that can affect the resonance characteristics of the piezoelectric ceramic component. For examples, these factors are the bonding conditions with the piezoelectric element, the magnitude of the input voltage, the normal force in the frictional drive and the emission of heat due to vibration and friction etc. Therefore, it is important to research properly the inclination for variation of piezoelectric ceramics in the circumstance where complex elements are involved. In this paper, we focus on the analysis of the resonance characteristics of an ultrasonic motor as a function of the magnitude of the input voltage and the normal force.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.404-407
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• 2004

Linear ultrasonic motor by bimorph. Transducer for linear ultrasonic motor with symmetric and anti-symmetric modes was studied. The transducer was composed of two piezoelectric ceramic that cross at right angles with each other at tip. In order to exist length vibration mode two piezoelectric ceramics must have 90-degree phase difference with each other. As a result, tip of transducer moves in elliptical motion. Elliptical trajectory of transducer was analyzed by employing the (mite element method(FEM). From the result, the linear ultrasonic motor was measured for characteristics. In this paper, vibration shape of transducer was simulated and the resonant frequency, stabilization frequency and maximum displacement were calculated using the FEA.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.287-288
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• 2008

에폭시-층상실리케이트 나노콤포지트의 균질분산과 층상실리케이트내로 침투되는 박리정도를 향상시키기 위해 친환경적 분산기법인 물리적방법으로 Homogenizer와 Power Ultrasonic를 적용한 기법을 실시하였다. Homogenizer의 최적속도를 얻기 위해 분산시킨 나노콤포지트의 박리정도, 유리천이온도를 구할 수 있었고, Homogenizer와 Ultrasonic을 동시에 적용하여 최적시간을 구하기 위해 적용된 나노콤포지트를 절연파괴 강도의 Weibull Plots을 통하여 판단할 수 있는 좋은 결과를 얻을 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.297-303
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• 2000

Natural convection heat transfer have been paid attention because it can be applied to various areas such as cooling of nuclear reactor, heat storing system and so on. Among such applications, the melting process of phase change material(PCM) has been actively studied. However most researches have focused on phase change heat transfer in natural melting. Therefore, In this paper, ultrasonic vibration was adopted to increase the melting rate. In addition, general relationship and corelationship between melting with ultrasonic vibration and melting without ultrasonic vibration have been established during the melting of PCM.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1349-1354
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• 2003

Ultrasonic Machining process is an efficient and economical means of precision machining on glass and ceramic materials. However, the mechanics of the process with respect to crack initiation and propagation, and stress development in the ceramic workpiece subsurface are still not well understood. In this research, we investigate the basic mechanism of chemical assisted ultrasonic machining(CUSM) of glass through the experimental approach. For the purpose of this study, we designed and fabricated the desktop micro ultrasonic machine. The feed is controlled precisely by using the constant load control system. During the machining experiment, the effects of HF(hydrofluoric acid) characteristics and machining condition on the surface roughness and the material removal rate are measured and compared.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.187-190
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• 2004

Transducer for ultrasonic linear motor with the symmetric and anti-symmetric modes was studied. The ultrasonic liner motor consists of two Lngevin type piezoelectric vibrators that cross at right angles with each other in tip. In order to excite symmetric and anti-symmetric mode, the transducer must have a 90 degree phase difference of voltage. Therefore, the tip of transducer moves on an elliptical motion. In this paper, the finite element analysis was used. The ultrasonic motor was fabricated using the simulated result and the driving characteristics were measured.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.316-319
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• 1996

In this study, characteristics of ultrasonic transducer fabricated with porous piezoelectric resonator are investigated, 3-D underwater object recognition using the self-made ultrasonic transducer and SOFM(Self-Organizing Feature Map) neural network are presented. The self-made transducer was satisfied the required condition of ultrasonic transducer in water, and the recognition rates for the training data and the testing data were 100 and 95.3% respectively. The experimental results have shown that the ultrasonic transducer fabricated with porous piezoelectric resonator could be applied for sonar system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.62-66
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• 2002

The preliminary results on the application of optical fiber sensor(OFS) for locations of ultrasonic signals in underwater are presented and analyzed. The OFS utilizing the principle of Sagnac interferometry was designed and the hollowed cylindrical mandrel wound by single mode optical fiber was used as sensing component. The ultrasonic signal source was simulated by the PZT actuator operated with function generator. It has been shown that the OFS could detect the signals less affected by ultrasonic path comparing to conventional acousto-electric sensor and accurate location of ultrasonic signal could be carried out using two OFSs.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.285-288
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• 1998

Ultrasonic signal characteristics related with the growth of electrical trees in epoxy resin are examined under 67[Hz] ac voltage application along with a CCD camera and PD current method. The ultrasonic sensor with a resonant frequency of 200[Hz] supported by a mechanical spring is attached directly to the lower-side of plane electrode. The magnitude of Partial discharge and count rate of ultrasonic signals have been measured according to the tree growth from a needle tip in an epoxy sample.