• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.5
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• pp.91-97
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• 2012

Recently, the performances of electrical and electronic devices are improving while the sizes are becoming smaller. As sound-generating systems, the two-dimensional speakers have been developed in place of conventional three-dimensional ones. Piezoelectric materials show the mechanical vibrations due to the voltage applied from outside the materials. The early film speakers had a limitations of output power in that it was not easy to make the conducting macromolecular films on the surfaces of the materials due to the internal chemical properties of materials. We have adopted the corona surface treatment in order to improve the output characteristics by increasing the adhesion of the coating material on to the surface of the center material of piezo film. The results showed the improvement of output power in the wider range of operating frequencies.

• Journal of KSNVE
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• v.21 no.4
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• pp.25-29
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• 2011

자기변형(magnetostriction)에 관한 연재물 3번째로 이번 호부터는 본격적으로 자기변형 현상을 이용한 구동기(actuator)의 이론적인 모델링에 대해서 알아보기로 한다. 아직 필자의 이해의 수준이‘달인’의 경지에 이르지 않은 탓에 대부분의 내용은 기존의 논문의 내용을 요약 정리하거나 여러 논문들 간의 시각의 차이를 드러내는 방식으로 진행할 것임에 대하여 사전에 양해를 구한다. 또한 이 연재에서는 주로 구동기에 대한 내용을 언급하고 있으나 자기변형 물질 역시 피에조 물질과 마찬가지로 센서로 사용하는 것이 가능하기 때문에 이 연재에서 설명하는 내용은 센서를 설명할 때도 많은 경우 그대로 혹은 약간의 변형을 거쳐서 사용할 수 있음을 언급해둔다.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.216-219
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• 2005

In this study, we will explain the design, test results and analysis of system for measuring the small mass in the microgravity environment. It is so difficult to measure the mass by sensing the gravity as the ground in the microgravity environment. The suggested method is to measure the resonance frequency of a sample. The resonance frequency may be measured as a function of mass. If we know the resonance frequency of the mass, we can guess the mass by detecting the resonance frequency. Piezoelectric ceramics have the characteristics that resonance frequency is changed by total mass which are its mass and the attached mass. This system have some problems but we verified that we can measure the unknown mass using the resonance frequency as the mass.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1591-1593
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• 2004

압력센서는 몇 가지 센싱 메카니즘을 가지고 있으므로 종류가 다양하고 크기 변에서도 여러 가지가 이용되고 있다. 최근에는 센싱 부분이 작으며 제어부분도 포함되는 ASIC화된 센서 시스템이 개발되고 있다. 여기에 이용되는 대부분의 탄성물질은 힘을 받았을 때 물질 내부의 벌크에서 저항 값이 변화하는 특성을 갖고 있다. 이러한 특성은 피에조 저항률(piezoresistivity)로 언급되며 스트레인 게이지의 감도에 영향을 주는 중요한 요소로 작용한다. 다이어프램으로 금속대선 세라믹을 사용하면 안정성이 우수한 특정을 가칠 수 있으며, 부식성 가스 류 및 화학성분에 대해서 내성이 강하고 환경변화에 따른 변형과 공정의 단순화 등 우수한 특성을 갖고 있는 것이 큰 장점이다. 센싱부는 산화 루세니움($RuO_2$)을 주 성분으로 하는 분말을 Paste화 하여 다이어프램 위에 스크린 프린팅을 하여 기본성능을 나타내었으며 특히, 상품화에서 중요한 일반성능에서는 온도 특성에 대한 Span 과 Offset 그리고 공정의 단순화에 대해서 고찰을 하였다.

• Proceedings of the KAIS Fall Conference
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• 2011.12b
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• pp.398-401
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• 2011

초음파의 응용분야에는 음파 성질을 이용한 정보 측정분야와 에너지를 이용한 용접 및 가공 등을 들수 있다. 초음파 용접의 경우 저항용접이나 용융 용접을 적용할 수 없는 재료의 접합에 이용되는데 이는 모재를 음극간에 놓고 압입하면서 초음파를 발신하여 그 진동을 이용하는 용접방법이다. 압전소자의 경우 피에조 물질을 사용하는데 일반적으로 $150^{\circ}C$이상에서 분자구조의 변형을 일으켜 제 역할을 못하게 된다. 본 연구에서는 압전소자와 공구혼의 온도를 최적으로 유지하기 위하여 추가적인 공기 유로와 방열핀을 설계하여 이것이 방열성능에 미치는 영향에 대해 고찰하였다.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.8
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• pp.735-741
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• 2015

Piezoelectric materials are well-utilized for transforming mechanical vibrations into electrical energy that can be stored and used to power a diversity of devices. In this work, these materials have been studied to improve the efficiency of a piezoelectric system, whereby the shape and vibration mode of a piezoelectric module was changed. The basic shape of the piezoelectric module used in this work comprises a width of 10 mm, a length of 30 mm, and a thickness of 0.2 mm. The structural design of the piezoelectric module is optimized using a Taguchi method to increase the corresponding electrical-energy generation. The maximum terminal voltage was defined as a characteristic value to evaluate the optimal design parameters. Through this work, we propose an optimal structure with an eccentric and centric mass; furthermore, the voltage increase of approximately 26% was obtained by comparing a general plate-vibrating piezosystem with an optimal plate-vibrating piezosystem.

• Journal of Satellite, Information and Communications
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• v.7 no.3
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• pp.22-25
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• 2012

In this paper, we proposed a method of the resonant frequency shift of a microstrip patch antenna using $LiNbO_3$, PVDF and FR-4 substrates. We designed and analyzed from these parametars optimized using Ensemble V 7.0 of the simulation tool. We observed the resonant frequency by DC appled electric field in a microstrip patch antenna. When $LiNbO_3$ substrate were applied from -300 to 300 V/mm, we obtained the resonant frequency shift of maximum 29 MHz. The microstrip patch antenna with PVDF (poly vinylidene fluoride) substrate, we obtained the resonant frequency shift of maximum 17 MHz at frequency 6 GHz. but when Epoxy FR-4 substrates used, the resonant frequency does not changed. This results showed the resonant frequency shift without physical strains in a microstrip patch antenna.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.215-223
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• 2005

Piezo-ceramics are special materials which transform energy from mechanical to electrical forms and vice versa. Bender elements are composite materials consisting of thin piezo-ceramics and elastic shims, and are widely used as actuators and transducers in the field of electronics, robotics, autos and mechatronics utilizing the effectiveness of energy transformation capability. In geotechnical engineering, commercial bender elements are used in laboratory as source and receiver in the measurements of soil stiffness. The elements were built by using various metal shims sandwiched between piezo-ceramics and coating over the composite in the research. A pair of elements were buried in a concrete block and used as source and receiver to measure the stiffness of the concrete. The test results were verified by comparing with the resonant column testing results. In a preliminary stage of the development of an in-situ seismic testing equipment using bender elements for soft clay materials, shear waves were generated and measured by burying the elements in the barrel of kaolinite and water mixture. The measured shear wave signals were so distinct for the first-arrival pick that applicability of the elements in the field measurements could be very promising.