• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1403-1405
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• 1994

In this study, the piezoelectric transducers with 1-3 connectivity have maded. A piezoelectric ceramic PZT prepared by Wet-Dry Combination method is used as a filler in Eccogel polymer matrix. The pulse-echo response for 1-3 type composite transducers were carried out in water. It was observed that the transmitting and receiving sensitivity of 1-3 type composite transducers were improved in comparison with that or solid PZT transducer. The reason is for that 1-3 composites have a hish piezoelectric voltage coefficients, The period of pulse-echo response for the transducer is in a good agreement with the resonant frequency of self-maded composite transducer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.219-221
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• 1993

In this study, piezoceramics/polymer composites with 3-3 connectivity were made by BURPS(Burnout Plastic Sphere) technique with PZT ceramics and plastic sphere. And the properties dependent on the Dextrin wt.% were investigated. The density of porous piezoceramic and piezoceramic/polymer composites were decreased almost linearly with increasing the Dextrin wt.%.

• E2M - 전기 전자와 첨단 소재
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• 제8권2호
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• pp.211-216
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• 1995

In this study, the piezoelectric ceramics/polymer composite transducers with 1-3 connectivity have been studied. A piezoelectric ceramics PZT prepared by Wet-Dry Combination method was used as a filler in polymer matrix Eccogel. We've got the pulse-echo response for 1-3 type piezc-electric composite transducers in water. It was shown that the transmitting and receiving sensitivity of 1-3 type piezoelectric composite transducers could be improved in comparison with that- of solid PZT transducers. The reason is for that 1-3 type Piezoelectric composites have low dielectric constant and density. There was in a good agreement between the resonant frequencies calculated from one period and observed results on the Ultrasonic Transducer Analyzer. According to these results we could be figured out the distance in water by virture of the pulse-echo response.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 추계학술대회 논문집
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• pp.205-208
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• 1995

PZT powders were prepared by the molten salt synthesis method. The porous PZT specimens were prepared from a mixture of PZT and Polyvinylalcohol(PVA) powders by BURPS(Burnout Plastic Sphere) technique. The pulse-echo response of PZT-polymer 3-3 type composite transducer with various PVA wt.% were studied, The fall time of pulse-echo response of PZT-polymer 3-3 type composite transducer was shorten to that of solid PZT-maded transducer. Therefore, a good transmitting and receiving properties could be obtained. The distance between transducer and reflector was in good agreement both solid PZT and PZT-polymer 3-3 type composite fabricated transducer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.756-759
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• 2003

In this study, an ultrasonic transducer is fabricated with a 1-3 type composite resonator. Pulse-echo responses of an ultrasonic transducer are investigated in underwater with the designated water-levels. LED output signals of a level limit switch with changing a water level are obtained by using the currently developed self-made 1-3 type composite transducer and electric measuring unit. LED is turned on at above the up-limit level with increasing a water level, and LED is turned on at less than the down-limit level with decreasing a water level.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 제5회 영호남 학술대회 논문집
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• pp.103-106
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• 2003

In this study, an ultrasonic transducer is fabricated with 1-3 type composite resonators. Pulse-echo responses of an ultrasonic transducer are investigated in underwater dependent on the variable designated water-level. LED Output signals of a level limit with changing a water level is obtained by the 1-3 type self-made composite transducer and electric measuring unit. LED is turned on at above the up-limit level with increasing a water level, and LED is turned on at less than the down-limit level with decreasing a water level. There was good agreement between the virtual water level and output LED signal by using the self-made water-detecting system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계합동학술대회 논문집
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• pp.224-228
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• 2002

In this study, the piezoelectric ceramics PZT powder was synthesized by the Wet-Dry combination method. Flexible 1-3 type composite specimens were fabricated with the piezoceramics PZT filler phase and Eccogel polymer matrix phase. This paper represents the pulse-echo response of the 1-3 type composite transducer to check it out to investigate a basic property regarding a level limit switch. The acoustic impedance of 1-3 type composite was improved than that of single phase PZT ceramics. The pulse-echo response of transducer fabricated with the self-made 1-3 type composites resonator was better than that of the solid PZT transducer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.292-295
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• 2003

In this study, an ultrasonic transducer is fabricated with 1-3 type composite resonators. Pulse-echo responses of an ultrasonic transducer are investigated in underwater dependent on the variable designated water-level. LED Output signals of a level limit with changing a water level is obtained by the 1-3 type self-made composite transducer and electric measuring unit. LED is turned on at above the up-limit level with increasing a water level, and LED is turned on at less than the down-limit level with decreasing a water level. There was good agreement between the virtual level and output LED signal by using the self-made water-detecting system.

• Composites Research
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• 제29권4호
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• pp.145-150
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• 2016

Polyvinylidene fluoride (PVDF)는 압전성을 나타내는 대표적인 고분자로 1960년대부터 많은 연구가 진행되어 왔다. PVDF는 반결정의 고분자로써 5가지의 결정 구조(${\alpha}$, ${\beta}$, ${\gamma}$, ${\delta}$, 그리고 ${\varepsilon}$형)로 구성되어 있다. ${\alpha}$형과 ${\delta}$형 결정은 전기적으로 반응하지 않는 무극성 결정구조이나 ${\beta}$형, ${\gamma}$형 그리고 ${\varepsilon}$형은 전기적으로 반응하는 극성 결정구조이다. 그 중에서도 ${\beta}$형 결정구조는 트랜스 형 분자 쇄가 평행으로 충진 된 형태로서 PVDF 단위체가 갖는 영구 쌍극자가 모두 한 방향으로 배열되어 있는 구조이기 때문에 자발 분극이 커지게 되고 압전성을 나타내게 된다. 일반적으로 ${\beta}$형 결정구조는 연신을 통한 ${\alpha}$형 결정구조의 변환을 통하여 얻을 수 있고, 연신 후 후처리 공정을 통해 그 양을 증가시킬 수 있다. 습식방사로 제조된 PVDF 섬유는 응고욕에서 극성 용매의 확산 메커니즘에 의해 ${\beta}$형 결정구조가 형성되는 장점을 가지고 있지만 극성 용매가 빠져나감과 동시에 섬유 고화가 진행되기 때문에 용매의 확산 경로가 섬유 내부 기공으로 남게 되는 단점을 가지고 있다. 이 기공은 폴링(Poling) 공정에서 전기장에 의한 분극을 방해하여 그 효과를 감소시키는 역할을 한다. 또한, PVDF 섬유가 압전 특성을 필요로 하는 응용분야에 사용되기 위해서는 섬유 가공 후에 전극이 반드시 부착되어야 하는데 섬유 형태로 제조된 PVDF에 전극을 형성하기는 매우 어렵다. 본 연구에서는 압전성을 갖는 PVDF 섬유를 습식 방사와 건식 방사의 혼합 공정으로 제조하여 기공 문제를 해결하였고, 전극이 섬유 내부에 삽입된 Core/Shell 형태의 PVDF 섬유를 제조하여 까다로운 전극형성 문제를 해결하였다.

• Composites Research
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• 제28권4호
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• pp.148-154
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• 2015

구조건전성 모니터링은 구조물에 발생된 손상을 조기에 감지 및 적절한 유지보수를 통해 재정적 혹은 인명 피해를 방지하기 위해 실시된다. 대부분의 능동센싱 기반 구조건전성 모니터링에서는 많은 수의 압전체(piezoelectric transducer) 센서와 구동기(actuator)를 필요로 한다. 구조건전성 모니터링 시 사용된 압전센서에 결합이 존재하는 경우, 구조물의 상태진단에 문제가 발생할 수 있다. 본 연구에서는 신뢰성 있는 구조건전성 모니터링 결과를 위해 임피던스 기반 센서 자가 진단법을 사용하여 다수 센서의 결함을 탐지하였다. 또한 사용된 접착제와 센서의 정보가 충분치 못한 경우, 사용된 센서로부터 측정된 데이터만을 토대로 센서결함 진단을 위한 알고리즘을 소개하였다. 알고리즘이 적용 가능한 온도 범위를 실험적으로 분석함으로써 개발된 기법이 실제 환경에서 응용이 가능함을 확인하였다.