• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.343-343
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• 2006

집적회로기판의 소형화 추세에 따라 커패시터, 인덕터, 저항과 같은 수동소자를 PCB 기판내부에 임베딩하는 연구가 국내외에서 활발하게 진행되고 있다. 본 논문에서는 polymer-metal-ceramic의 3상 복합체 구조를 가지는 임베디드 커패시터에서 Bimodal PZT분말에 따른 유전 특성에 대하여 고찰하였다. 매트릭스를 형성하는 고분자 재료로는 PMMA(polymethyl methacrylate)를 사용하였으며, 충분히 혼합된 분말을 고온에서 프레싱하여 시편을 제조하였다. 유전특성은 임피던스분석기 및 LCZ 미터를 이용하여 측정하였으며, 실험결과는 혼합법칙과 Percolation 이론을 이용하여 해석하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.869-872
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• 2000

The aim of present work was to fabricate the piezoelectric composite materials of low megahertz applications such as non-destructive testing of materials. Among all the various composites, those with PZT rods embedded in Spurrs epoxy with regular periodicity (1-3 connectivity) was fabricated by dice and fill method. The fabricated size of the PZT cell were 0.18X0.18, 0.28X0.28mm$^2$, respectively. And the volume ratio of the PZT cell were 52, 64%, respectively. The resonant frequency and anti-resonant frequency of the composites were 3.5 MHz and 4.3MHz, respectively. The piezoelectric coupling coefficient were about 38 and 37% and the mechanical quality factor were about 12.7 and 22. These value were very different from these of bulk PZT Plate.

• Proceedings of the KIEE Conference
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• 1993.11a
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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.%.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.7
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• pp.447-452
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• 1987

In this paper, the dependence of piezoelectric properties in the 0-3 composite system of piezoelectric-ceramics polymer materials on particle size of ceramics were investigated. Radial mode and thickness mode of composite were observed similar to single phase of piezoelectric ceramics. The measured values of dielectric constant and dissipation factor were dependent on particle size, which increased with the increasing particle size. the planar coupling factor, thickness coupling factor and thickness frequency constant with the particle size were almost constant, while planar frequency constant increased. The thickness coupling factor decreased with the increasing thickness of specimen. It is found that maximum voltage coeffidient was calculated on the specimen with particle size smallar than 46 ${\mu}m$.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.7
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• pp.324-325
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• 2001

In this study, the characteristics of ultrasonic sensor fabricated with PZT-Polymer 1-3 type composites are investigated. The 3-D Underwater object recognition using the self-made ultrasonic sensor and SOFM neural network is presented. The ultrasonic sensor is satisfied with the required condition of commercial ultrasonic sensor in underwater. The 3-D underwater object recognition for the training data and the testing data are 100[100%], respectively. The experimental results have shown that the ultrasonic sensor fabricated with PZT-Polymer 1-3 type composites can be applied for sonar system.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.935-937
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• 1999

In this study, 1-3 type composite specimens were fabricated with PZT powders prepared by the molten-salt synthesis method and Eccogel polymer matrix. A virtual level-meter was fabricated with a 1-3 type composite probe and electronic unit for underwater application. There was no difference in values between a virtual and measured level on its level meter.

• Journal of Mechanical Science and Technology
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• v.16 no.5
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• pp.666-675
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• 2002

Piezoelectric Fiber Composites with Interdigitated Electrodes (PFCIDE) were previously introduced as an alternative to monolithic wafers with conventional electrodes for applications of structural actuation. This paper is an investigation into the performance improvement of piezoelectric fiber composite actuators by changing the matrix material. This paper presents a modified micro-electromechanical model and numerical analyses of piezoelectric fiber/piezopolymer matrix composite actuator with interdigitated electrodes (PFPMIDE). Various concepts from different backgrounds including three-dimensional linear elastic and dielectric theories have been incorporated into the present linear piezoelectric model. The rule of mixture and the modified method to calculate effective properties of fiber composites were extended to apply to the PFPMIDE model. The new model was validated when compared with available experimental data and other analytical results. To see the structural responses of a composite plate integrated with the PFPMIDE, three-dimensional finite element formulations were derived. Numerical analyses show that the shape of the graphite/epoxy composite plate with the PFPMIDE may be controlled by judicious choice of voltages, piezoelectric fiber angles, and elastic tailoring of the composite plate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.346-346
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• 2007

압전세라믹 재료는 현재 압전 변압기, actuator, transducer, sensor, speaker 등에 광범위하게 이용이 되고 있다. 이 중에서 압전세라믹 소결체를 이용한 스피커의 제조는 가공이 까다롭고, 대형의 크기로 제작 시 소자가 깨지는 등의 많은 제약을 받고 있으며, 저음 특성이 떨어져 응용 범위가 한정되어 있다. 따라서 최근에는 이러한 단점을 극복하기 위하여 세라믹/고분자 복합체를 이용한 필름 스피커를 제작하고자 시도하고 있다. 이러한 세라믹/고분자 0-3형 압전 복합체를 이용할 경우, 제품의 경량화를 실현할 수 있고, 크기나 환경의 영향을 거의 받지 않으므로, 고기능성 스피커로의 응용에 적합할 것으로 보인다. 따라서 본 연구에서는 PZT계의 세라믹와 PVDF, PVDF-TrFE, Polyester, acrylic resin 등의 여러 고분자 물질과의 복합체를 제조하여 압전특성을 평가하였다. 본 실험은 먼저 $(Pb_{1-a-b}Ba_aCd_b)(Zr_xTi_{1-x})_{1-c-d}(Ni_{1/3}Nb_{2/3})_c(Zn_{1/3}Nb_{2/3})_dO_3$ (이하 PZT라 표기)의 최적화 조성을 선택하여, $1050^{\circ}C$에서 소결된 분말을 48시간 ball milling방법 로 약 $1{\mu}m$ 크기로 분쇄하였다. 고분자 물질들은 알맞은 용제들을 선택하여 녹였다. 그 다음 소결된 PZT분말과 고분자를 50:50, 60:40, 65:35, 70:30등의 무게 분율로 혼합하고, 분산제, 소포제 등을 첨가하여 3단 roll mill을 이용하여 충분히 분산시켜 페이스트 (Paste)를 제조하였다. 제조된 페이스트를 ITO가 코팅된 PET필름 위에 스크린 프린팅 법을 사용하여 인쇄하여 $120^{\circ}C$에서 5분간 건조하였다. 코팅된 복합체의 두께는 약 $80{\mu}m$ 정도로 측정되었다. Ag 페이스트를 이용한 상부 전극 형성에도 스크린 프린팅 법을 적용하였다. 이를 $120^{\circ}C$에서 4 kV/mm의 DC 전계로 분극 공정을 수행한 후 전기적 특성을 평가하였다. 유전특성을 조사하기 위해서 LCR meter (EDC-1620)를 사용하였고, 시편의 결정구조는 XRD (Rigaku; D/MAX-2500H)을 통해 분석하였으며, 전자현미경(SEM)을 이용하여 미세구조를 분석하였다. 압전 전하상수$(d_{33})$ 값은 APC 8000 모델을 이용하여 측정하였다. PZT의 혼합비가 증가할수록 비유전율 및 압전 전하 상수 등의 전기적 특성이 증가되었다. 또 여러 고분자 물질 중에서 PVDF-TrFE 수지가 가장 우수한 특성을 보였다. 이는 PVDF-TrFE 수지가 압전성을 나타내기 때문인 것으로 판단되었다.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1537-1539
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• 1998

In this study, 3-D underwater object restoration using ultrasonic transducer fabricated with PZT-Polymer 1-3 type composite are presented. Using the acquired underwater object data 16${\times}$16 pixels. Modified SCL neural networks using the 16${\times}$16 low resolution image was used for underwater object restoration of 32${\times}$32 high resolution Image.