• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.3307-3309
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• 1999

Electrochemical discharge machining (ECDM) is a very recent technique in the fabrication of the micro-electro-mechanical system ( MEMS ) devices. This paper presents the experimental results of the machining of micro-holes on pyrex glass substrates by use of ECDM. Electrolyte is used with a KOH aqueous solution, cathode with copper, anode with platinum, and tool feed system is applied with gravity feed system. Already established experimental results were taken under the condition of constant voltage frequency. However in this paper, the effect of variation of the voltage frequency and duty ratio is considered. In this experiment, it is measured the ECDM performances with variation of the voltage frequency and duty ratio under the conditions of constant other machining variables. ECDM performances are described by the hole depth, and the top hole diameter.

• 한국전산구조공학회논문집
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• 제26권4호
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• pp.271-274
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• 2013

경사계 센서는 여러분야에서 널리 적용되고 있는 센서 중의 하나이다. 특히 건축분야에서는 초고층 건물의 수직도와 수평도를 계측하고 모니터링하는데 적용되어 왔다. 최근 미소전기기계 시스템(MEMS: Micro Electro-Mechanical System)기술의 발달로 인해 많은 센서들이 개발되었다. 본 논문에서 논하고자 하는 MEMS형 경사계는 MEMS형 가속도계를 기반으로 한다. 정지한 상태에서 가속도계로 계측되는 정적 가속도와 중력가속도 사이의 관계를 이용하면 센서에 발생하는 경사를 계측할 수 있기 때문이다. 이러한 원리 때문에 좀 더 정확하고 이점을 갖는 경사계가 개발되었다. 보 실험을 통하여서 레이저 변위계와의 차이를 검증하였다. 실험결과 무선 MEMS형 경사계 센서 시스템은 높은 정확도, 안정성, 장기모니터링에 대한 경제성을 갖는 유용한 시스템임을 확인할 수 있었다. 결론적으로 무선 MEMS형 경사계 센서 시스템은 건축분야에서 그리고 다른 여러 산업분야에서 정확하고 편리한 모니터링 시스템으로 적용될 수 있을 것으로 판단된다.

• 센서학회지
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• 제14권4호
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• pp.265-271
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• 2005

In this study, a variable capacitive pressure sensor is fabricated for TPMS (Tire Pressure Monitoring System). This study is for developing sensors which consecutively measure the tire pressure given as 30 psi from the industrial standard. For improving non-linearity of the prior capacitive pressure sensors, it is suggested that touch mode capacitive pressure sensor be applied. In addition, initial capacitance is designed as small as possible for the conformity to the wireless sensor. ANSYS, commercial FEA package, is used for designing and simulating the sensor. The device is progressed by MEMS (Micro Electro Mechanical Systems) fabrication and packaged with PDMS. The result is obtained sensitivity, 1 pF/psi, through a pressure test. The simulation result is discrepant from experiment one. Wafer's uniformity is presumed as the main reason of discrepancy.

• Structural Engineering and Mechanics
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• 제65권4호
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• pp.491-504
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• 2018

Because of sandwich structures with low weight and high stiffness have much usage in various industries such as civil and aerospace engineering, in this article, buckling and free vibration analyses of coupled micro composite sandwich plates are investigated based on sinusoidal shear deformation (SSDT) and most general strain gradient theories (MGSGT). It is assumed that the sandwich structure rested on an orthotropic elastic foundation and make of four composite face sheets with temperature-dependent material properties that they reinforced by carbon and boron nitride nanotubes and two flexible transversely orthotropic cores. Mathematical formulation is presented using Hamilton's principle and governing equations of motions are derived based on energy approach and applying variation method for simply supported edges under electro-magneto-thermo-mechanical, axial buckling and pre-stresses loadings. In order to predict the effects of various parameters such as material length scale parameter, length to width ratio, length to thickness ratio, thickness of face sheets to core thickness ratio, nanotubes volume fraction, pre-stress load and orthotropic elastic medium on the natural frequencies and critical buckling load of double-bonded micro composite sandwich plates. It is found that orthotropic elastic medium has a special role on the system stability and increasing Winkler and Pasternak constants lead to enhance the natural frequency and critical buckling load of micro plates, while decrease natural frequency and critical buckling load with increasing temperature changes. Also, it is showed that pre-stresses due to help the axial buckling load causes that delay the buckling phenomenon. Moreover, it is concluded that the sandwich structures with orthotropic cores have high stiffness, but because they are not economical, thus it is necessary the sandwich plates reinforce by carbon or boron nitride nanotubes specially, because these nanotubes have important thermal and mechanical properties in comparison of the other reinforcement.

• Tribology and Lubricants
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• 제33권6호
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• pp.282-287
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• 2017

SU-8 is an epoxy-type photoresist widely used for the fabrication of high-aspect-ratio (HAR) micro-structures in micro-electro-mechanical systems (MEMS). To fabricate highly integrated structures, chemical mechanical polishing (CMP) has emerged as the preferred manufacturing process for planarizing the MEMS structure. In SU-8 CMP, an oxidizer decomposes organic impurities and particles in the CMP slurry remove the chemically reacted surface of SU-8. To fabricate HAR microstructures using the CMP process, the adhesion between SU-8 and substrate material is important to avoid the delamination of the SU-8 film caused by the mechanical-dominant material removal characteristic. In this study, the friction force during the CMP process is measured with a CMP monitoring system to detect the delamination phenomenon and investigate the delamination of the SU-8 film from the silicon substrate under various pressure conditions. The increase in applied pressure causes an increase in the frictional force and wafer-edge stress concentration. The frictional force measurement shows that the friction force changes according to the delamination phenomenon of the SU-8 film, and that it is possible to monitor the delamination phenomenon during the SU-8 CMP process. The delamination at a high applied pressure is explained by the effect of stress distribution and pad deformation. Consequently, it is necessary to control the pressure of polishing, which can avoid the delamination in SU-8 CMP.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.181-181
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• 2008

DLC (Diamond-like Carbon) 박막은 높은 내마모성과 낮은 마찰 계수, 화학적 안정성 및 적외선 영역에서의 높은 투과율과 낮은 광 반사도, 높은 전기저항과 낮은 유전율, 전계방출특성 등 여러 가지 장점을 가진 물질이다[1]. 최근에는 DLC 박막의 여러 장점들과 산과 염기 유기용매에 대한 화학적 안정성으로 인하여 인조관절에서 인공심장의 판막에 이르기까지 의공학 관련 부품소재로 응용되고 있으며 내구성과 안정성에 있어서 탁월한 성능을 보여주고 있다. 또한 DLC 박막의 높은 경도와 낮은 마찰 계수, 부드러운 박막 표면 (수nm의 RMS 거칠기)의 장점을 살려 마그네틱 미디어와 하드디스크의 슬라이딩 표면에 사용되어지고, MEMS (Micro-Electro Mechanical System) 소자와 MMAs (Moving Mechanical Assemblies)의 고체윤활코팅으로 활용하여 미세기계의 내구성과 성능 향상을 도모할 수 있다. 이와 같이 DLC 박막은 다양한 분야에 응용되고 있으며, 박막이 지닌 여러 가지 장점들로 인하여 더 많은 분야에 응용될 가능성을 지닌 물질이다. 그러나 수 ${\mu}m$이상의 두께에서 박막이 높은 잔류응력 (residual stress)을 가지고, 열에 취약하여 이의 개선에 관한 연구들이 진행되어 지고 있다 [2]. 따라서 사용되는 목적에 따라 용도에 맞는 양질의 DLC 박막을 합성하기 위해선 합성 장치의 개발과 다양한 실험을 통한 최적의 합성조건 도출 등의 노력이 요구된다. 또한 DLC 박막 합성시의 여러 가지 증착 방법에 따른 박막 물성에 대한 재현성 확보 및 박막 증착에 관한 명확한 메커니즘 규명이 아직까지는 불분명하여 이에 관한 연구가 시급하다. 따라서 본 연구에서는 MEMS 소자와 MMAs의 고체윤활코팅으로 사용가능한 DLC 박막을 RF PECVD (Plasma Enhanced Vapor Deposition) 방식으로 합성하고 후열처리 온도에 따른 DLC 박막의 마찰계수 변화를 박막에 훼손을 주지 않는 FFM (Friction Force Microscopy) 방식을 사용하여 분석하였다.

• 한국정보통신학회논문지
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• 제23권11호
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• pp.1397-1406
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• 2019

신경학적 손상에 의한 언어장애인/비장애인 간의 일상적인 휴대폰 통화시 신경학적 손상으로 인한 발음의 정확도와 언어장애인의 발음 특징이 결합되어 원활한 의사소통을 저해하는 경우가 많다. 이러한 문제점을 개선하기 위하여 제한하는 방법은 언어장애인 특성에 맞춘 단어의 모호성(out of vocabulary) 개선과, 언어 장애인 구강 특성에 따른 어려운 발성 부분을 인위적으로 보정해주는 유도선이 포함된 MEMS(Micro Electro-mechanical System) Microphone 장치 개선이다. S/W적 개선은 도치기능이 포함된 결정트리이며, 연속어 특성을 감안하여 개선된 matrix-vector rnn 방법을 제시하였다. H/W와 S/W 특성을 감안하여 유사 사전을 만들어 원활한 의사소통을 위한 말명료도 향상에 기여하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1286-1289
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• 2004

A new thermal bimorph actuator for large out-of-plane displacement is designed, fabricated and tested. The deflecting beam is composed of polyimide, heater, and polyvinyl difluorides with tetrafluoroethylene(PVDF-TrFE). The large difference of coefficient of thermal expansion(CTE) of two polymer layers (polyimide and PVDF-TrFE) can generate a large deflection with relatively small temperature rising. Compared to the most conventional micro actuators based on MEMS(micro-electro mechanical system) technology, a large displacement, over 1 mm at 20 mW, could be achieved. The proposed actuator can find applications where a large vertical displacement is needed while keeping compact overall device size, such as a micro zooming lens.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2002년도 추계학술대회 논문집
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• pp.53-54
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• 2002

Plasma ignition method has been applied in various fields particularly to the rocket propulsion, pyrotechnics, explosives, and to the automotive air-bag system. Ignition method for those applications should be safe and also operate reliably in hostile environments such as; electromagnetic noise, drift voltage, electrostatic background and so on. In the present study, a semiconductor bridge (SCB) plasma ignition device was fabricated and its plasma characteristics including the propagation speed of the plasma, plasma size, and plasma temperature were investigated with the aid of the visualization of micro scale plasma $(i.e.,\;\leq\;350\;{\mu}m)$, which generated from a Micro-Electro-Mechanical poly-silicon semiconductor bridge (SCB).

• Smart Structures and Systems
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• 제18권4호
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• pp.787-800
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• 2016

The aim of the paper is to analyze nonlinear transverse vibration of an embedded piezoelectric plate reinforced with single walled carbon nanotubes (SWCNTs). The system in rested in a Pasternak foundation. The micro-electro-mechanical model is employed to calculate mechanical and electrical properties of nanocomposite. Using nonlinear strain-displacement relations and considering charge equation for coupling between electrical and mechanical fields, the motion equations are derived based on energy method and Hamilton's principle. These equations can't be solved analytically due to their nonlinear terms. Hence, differential quadrature method (DQM) is employed to solve the governing differential equations for the case when all four ends are clamped supported and free electrical boundary condition. The influences of the elastic medium, volume fraction and orientation angle of the SWCNTs reinforcement and aspect ratio are shown on frequency of structure. The results indicate that with increasing volume fraction of SWCNTs, the frequency increases. This study might be useful for the design and smart control of nano/micro devices such as MEMS and NEMS.