• 비파괴검사학회지
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• 제9권1호
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• pp.69-76
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• 1989

Piezoelectric elements, backing and shoe material are the important components of the ultrasonic transducer. In this study, characteristic constants in the domestic and the foreign PZT ceramic elements are investigated, The acoustic properties of the domestic and the foreign backing and shoes are characterized. The effects of components characteristics, the kinds of the piezoelectric elements and the thickness of the wear plates are investigated for the manufactured normal beam ultrasonic transducers.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.373-376
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• 2000

The modified Moonie(Cymbal) transducer has been investigated for an accelerometer application. This paper present a wind-mill type ultrasonic motors using ternary piezoelectric ceramics and aluminum endcaps applied by cymbal transducer. The maximum displacement was increased depend on applied voltage and layer number. The multi-layer was fabricated by tape casting using doctor-blade process. The maximum displacement of multi-layered ultrasonic motor was much higher than that of one-layered.

• 센서학회지
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• 제29권1호
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• pp.33-39
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• 2020

Typically, photoacoustic images are obtained in water or gelatin because the impedance of these mediums is similar to that of the human body. However, these acoustic mediums can have an additional mass effect that changes the resonance frequency of the transducer. The acoustic radiation impedance in air is negligible because it is very small compared to that of the transducer. However, the high acoustic impedance of mediums such as the human body and water is quite large compared to that of air, making it difficult to ignore. Specifically, in a case where the equivalent mass is very small, such as with a micro-machined ultrasound transducer, the additional mass effects of the acoustic medium should be considered for an accurate resonance frequency design. In this study, a piezoelectric micro-machined ultrasonic transducer (pMUT) was designed to have a resonance frequency of 10 MHz in the acoustic medium of water, which has similar impedance as the human body. At that time, the resonance frequency of the pMUT in air was calculated at 15.2 MHz. When measuring the center displacement of the manufactured pMUT using a laser vibrometer, the resonance frequencies were measured as 14.3-15.1 MHz, which is consistent with the finite element method (FEM) simulation results. Finally, photoacoustic images of human hair samples were successfully obtained using the fabricated pMUT.

• 한국음향학회지
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• 제28권6호
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• pp.491-498
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• 2009

본 논문에서는 수중 음향 압전 트랜스듀서의 고효율, 정전력 구동이 가능하도록 절연 트랜스포머와 체비셰프 필터함수를 이용한 임피던스 정합회로 설계 방안을 제안하였다. 제안된 정합회로는 진동과 무관한 트랜스듀서의 리액턴스 성분을 최소화하고 넓은 동작주파수 범위에서 평탄한 출력 전력 특성을 갖도록 설계되었다. 체비세프 필터함수를 표준 원함수로하는 저역통과 필터를 단종단 제자형 회로로 설계하고 대역통과 주파수변환을 통하여 트랜스듀서의 등가모델과 트랜스포머의 권선비에 적합한 정합회로를 설계하였다. 제안된 기법을 예제 모델 Tonpilz형 압전 트랜스듀서에 대한 가상부하에 적용하고 시뮬레이션과 실험을 통하여 그 결과를 비교함으로써 제안된 기법의 타당성을 검증하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.1171-1172
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• 2011

• 한국전기전자재료학회논문지
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• 제37권2호
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• pp.141-147
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• 2024

강유전체, 압전체 및 전왜 재료의 전기-기계적 반응의 기본 원리를 이해하기 위해 전기장 인가에 따른 변형 측정법은 널리 사용되고 있다. 특히, 전기 자극에 반응하는 압전 재료의 변형 특성을 이해하는 것은 압전 액츄에이터, 음향 장치, 초음파 발생기와 같은 부품을 연구하고 개발하는 데 중요하다. 이 튜토리얼 논문에서는 다양한 산업 분야에서 널리 사용되는 변위 측정 장치인 선형 가변 차동 변환기(linear variable differential transducer, LVDT)의 구성 요소와 작동 원리를 소개한다. 또한 전기장을 인가하여 강유전체, 압전체 또는 전왜 재료의 변형 특성을 측정하기 위해 LVDT를 사용하는 실험 장치의 구성을 소개한다. 그리고 이 논문에는 LVDT 실험 장치를 통해 얻은 간단한 측정 결과와 분석이 포함되어 있어서 다양한 재료의 전기-기계 상호 작용 연구 방법에 대해 유용한 정보를 제공한다.

• 한국음향학회지
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• 제32권5호
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• pp.393-401
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• 2013

본 논문에서는 $48{\times}64$ 채널로 이루어진 압전단결정 2D 배열형 초음파 트랜스듀서의 설계, 제작 및 평가를 하였다. 전기적 연결이 용이한 평면배열 구조를 선정한 후, 그에 맞게 구성소자를 제작하였다. 유한요소 해석을 통하여 트랜스듀서의 세부 구조를 설계하였다. 트랜스듀서의 성능을 향상시키기 위해 치폭의 너비와 재료를 조절하여 소자간 상호간섭을 저감하고, 압전단결정 및 정합층의 최적 두께를 설계하여 목표 주파수 대역폭을 구현하였다. 설계에 따라 트랜스듀서의 시작품을 제작하고 그 특성을 측정한 후, 측정된 결과를 유한요소 해석 결과와 비교하여 개발된 트랜스듀서의 성능을 평가하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 춘계학술대회 논문집
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• pp.1-4
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• 1995

The most of conventional ultrasonic transducers are constructed to generate either longitudinal or shear waves, but not both of them. We investigated the mechanism of dual mode transducers that generates both of the longitudinal and shear waves simultaneously with a single PZT element. The study has been aimed to find the desired cut by the examining the piezoelectric properties. Theory predicts that a mixed P/S mode transducer can be constructed using a related Z-cut of a PZT ceramics. We studied the performance of a PZT element as a function of its rotation angle so that its efficiency is optimized to excite the two waves equally strongly. The results are verified by checking the impedance variation of the element with Finite Element Methods, and chocking the wave form by pulse-echo test simulation. Based upon the theory a rotated Z-cut was prepared and a transducer were fabricated. Validity of the theory calculation is verified through the

• 한국음향학회:학술대회논문집
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• 한국음향학회 2004년도 춘계학술발표대회 논문집 제23권 1호
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• pp.311-314
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• 2004

A new type of high frequency wideband ultrasonic transducer with a separation between a transmitter and a receiver was proposed and its characteristics were simulated using the PSpice model. The piezoelectric ceramic $PbTiO_{3}$ as a transmitter and the piezoelectric copolymer P(VDF-TrFE) as a receiver were used for high sensitivity and wide bandwidth, respectively. The characteristics of a center frequency approximately 40MHz focusing transducer fabricated in this study showed very wide bandwidth which could give an axial spatial resolution better than 30um in the B-mode image for biological tissues.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1997년도 영남지회 학술발표회 논문집 Acoustic Society of Korean Youngnam Chapter Symposium Proceedings
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• pp.40-43
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• 1997

It is known tat the echoes from the most objects differ from the incident pulses in amplitude and frequency .Especially, the frequency in echoes from moving target is shiftby the Doppler effect. it causes to reduce the receiving sensitivity of piezoelectric transducers that have definite band width. The electric impedance, whichis connected to the electrical terminals, notably changes the resonant frequency of a thickeness mode piezoelectric vibrator with high electromechanical doupling due to the electroelastic effect. Using this effect, we have developed a frequency controllable ultrasonic transducer which is mad eof multi-layered PZT disks to adjust to frequency shifted by Doppler effect. The characteristics of transducer can be obtained by using the equivalent circuit of transmission line model. It was confirmed experimentally that the center frequency and band width of the trasducer could be controlled by the conditions of the electrical terminals. These results coincided with theoretical results.