• Proceedings of the Korean Fiber Society Conference
• /
• 2002.04a
• /
• pp.437-438
• /
• 2002

Poly(vinylidene fluoride)(PVDF)는 우수한 화학적 특성을 갖는 불소계 고분자로서 엔지니어링 플라스틱, 압전성 소재 및 봉합사용 소재로 이용되고 있다. 최근에는 PVDF의 화학적 개질을 통하여 전도성 고분자나 탄소섬유화 등의 기능성 소재로 만들려는 연구가 흥미롭게 이루어지고 있다. PVDF를 알칼리 처리하여 주쇄에 공액이중결합을 도입함으로써 전도성 고분자용 소재 또는 접착력이 개선된 PVDF 소재를 만들 수 있다. (중략)

• The Journal of the Acoustical Society of Korea
• /
• v.30 no.8
• /
• pp.436-445
• /
• 2011

In this paper, equivalent properties of 2-2 mode piezocomposites were studied. Variation of the properties of 2-2 mode piezocomposites was analyzed by the finite element method, and the result was compared with experimental measurement data to confirm the validity of the analysis. The equivalent properties of a single phase material to represent the piezocomposite composed of PZT-5H and polymer were derived by the asymptotic averaging method. Accuracy of the derived equivalent properties was enhanced by minimizing the discrepancy between the impedance spectra of full 2-2 piezocomposite and equivalent single phase material resonators of various vibration modes by the least square method. The equivalent properties of 2-2 piezocomposites derived in this study can be utilized to the design of diverse acoustic sensors.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.41 no.11
• /
• pp.743-748
• /
• 2017

For diseases that are difficult to detect by conventional imaging techniques, the development of a diagnostic method that allows sensors to be inserted into the human body to aid the diagnosis of local spots of the target tissue, is highly desirable. In particular, it is extremely difficult to determine whether vulnerable plaque can later develop into atherosclerosis using only imaging techniques. However, vulnerable plaques are expected to have slightly different mechanical properties than healthy tissue. In this study, we aim to develop a piezoelectric cantilever-type sensor that can be inserted into the human body and can detect the local mechanical properties of the target tissue. A piezoelectric polymer composite based on $BaTiO_3$ nanoparticles was optimized for fabrication of a piezoelectric cantilever. Next, a micro-cone tip was fabricated at the end of the piezoelectric cantilever by thermal drawing. Finally, stiffness of biological tissue samples was measured with the piezoelectric cantilever sensor for verifying its functionality.

• Composites Research
• /
• v.15 no.5
• /
• pp.7-13
• /
• 2002

The piezoelectric thin film sensor has good characteristics to observe the impact responses of composite structures. The capabilities for monitoring impact behavior of Gr/Ep laminates subjected to damage-induced impact using the PVDF(polyvinylidene fluoride) film sensor were examined. For a series of low-velocity impact tests from low energy to damage-induced energy, simulated sensor signals were compared with measured signals and the PVDF film sensor. Local impact damages(matrix cracking and delamination) were found at three impact tests, but the measured signals agreed well with the simulated sensor signals based on the linear relationship between the impact forces and the PVDF film sensor signals. And the inverse technique was applied to reconstruct the impact forces using the PVDF film sensor signals. Most of reconstructed impact forces had good agreement with the measured forces. The comparison results showed that the local damage due. to low-velocity impact didn't disturb the global impact responses of composite laminates and the reconstruction of impact forces from PVDF sensor signals wasn't affected by the local damage.

• Proceedings of the Korean Fiber Society Conference
• /
• 2002.04a
• /
• pp.439-442
• /
• 2002

나일론 m형의 폴리아미드계 고분자의 경우 m의 수가 홀수일 때 N-H와 C=O 사이의 dipole 배열에 의하여 거대한 dipole moment가 나타나기 때문에 극성 결정구조를 나타내게 되며(1), 그 중에서도 특히 나일론 7과 11은 압전성을 나타낸다. 한편, 나일론 11[poly(undecanolactam)]은 $\alpha$, $\beta$, ν, $\delta$, $\delta$' 형과 같이 적어도 다섯 개의 결정형태를 갖는데[2-3], 이러한 여러 가지의 결정형태는 시료의 제조조건과 열처리 조건 등에 따라서 달라진다. (중략)

• Proceedings of the KIEE Conference
• /
• 1993.11a
• /
• pp.219-221
• /
• 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 Journal of the Acoustical Society of Korea
• /
• v.17 no.6
• /
• pp.23-28
• /
• 1998

고분자 압전 필름인 PVDF를 이용하여 단일막과 이층막의 초음파 변환기를 제작하 여 임펄스 응답특성을 이론식에서 계산하여 실험적으로 확인하여 보았다. 또한 RF 펄스를 이용하여 초음파 변환기의 다층막에 따른 주파수 특성을 조사하였다. 그 결과 임펄스 응답 특성은 이론식과 잘 일치하였으며, 단일막의 변환기가 이층막에 비하여 지속시간이 짧은 펄 스를 나타내었다. RF펄스에 대한 주파수특성은 이층막의 변환기가 단일막에 비하여 광대역 의 특성을 나타냄을 알 수 있었다.

• Proceedings of the KIEE Conference
• /
• 1998.11c
• /
• pp.804-806
• /
• 1998

In this study, piezoelectric composites with 1-3-0 connectivity have been studied. A Piezoelectric ceramic PZT Prepared by Wet-Dry Combination method is used as a filler in mixture of Eccogel polymer matrix and third Phase. The density and stiffness of 1-3-0 type composites were decreased with increasing the third phase.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.710-713
• /
• 2003

The PZT(KP12) powder was synthesized by sintering at $1250^{\circ}C$ for 2hrs and wet milling for 24 hrs. The PZT composite mixed with PVdF was fabricated into bulk, sheet, and plate type and the characteristics of three types were estimated. The bulk type which has PZT volume percent of 70 showed the best piezoelectric constant. Dielectric constant increased exponentially as an increase of PZT volume percent. The figure of merit of bulk and plate type was better than pure PZT over PZT volume percent of 50.

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