• 항공우주시스템공학회지
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• 제15권6호
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• pp.1-9
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• 2021

In this study, a new design of an extension-type actuator (ExACT) is proposed based on a chevron structure with displacement amplification mechanisms by local heating. ExACT comprises diamond-shaped displacement amplification structures (DASs) containing axially oriented V-shaped chevron beams, a support bar that restricts lateral heat deformation, and a loading slot for thin-film heaters. On heating the thin film heater, the diamond-shaped DASs undergo thermal expansion. However, lateral expansion is restricted by the support bar, leading to displacement amplification in the axial direction. The performance parameters of ExACT such as temperature distribution and extended displacement is calculated using thermo-mechanical analysis methods with the finite element method (FEM) tool. Subsequently, the ExACTs are fabricated using a polymer-based 3D printer capable of reproducing complex structures, and the performance of ExACTs is evaluated under various temperature conditions. Finally, the performance evaluation results were compared with those of the FEM analysis.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.247-247
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• 2009

In this work, Ga-doped ZnO (GZO) thin films for toxic gas sensor application were deposited on low temperature co-fired ceramic (LTCC) substrates, by RF magnetron sputtering method. LTCC is one of promising materials for integration with heater, low cost production and high manufacturing yields than silicon substrate. The LTCC substrates with thickness of $400\;{\mu}m$ were fabricated by laminating 12 greentapes which consist of alumina and glass particle in an organic binder. The GZO thin films deposited on the substrates and were analyzed by X-ray diffraction method (XRD) and field emission scanning electron microscope (FESEM). The films are well crystallized in the hexagonal (wurzite) structure with increasing thickness. The fabricated sensors showed good sensitivity and fast response time to common types of toxic gases (NOx, COx).

• 전자공학회논문지D
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• 제35D권11호
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• pp.46-54
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• 1998

직선 또는 필라멘트 모양의 NiCr 박막 히터 및 Bi-Sb 박막 열전퇴(thermopile)로 구성되는 평면형 Bi-Sb 다중접합 열전변환기를 제작하고, 10 Hz에서부터 10 ㎑까지의 교류 입력신호에 대한 변환기의 교류-직류 변환 특성을 논의하였다. 변환기의 열감도를 증가시키고 또한 교류-직류 변환오차를 감소시키기 위하여, NiCr 히터 및 Bi-Sb 열전퇴의 고온 접합부를 열차단막 역할을 하는 Si₃N₄/SiO₂/Si₃N₄ 다이아프램위에 각각 형성하였고, 열전퇴의 저온 접합부는 방열판 역할을 하는 실리콘 림(rim)에 의해 지지되는 Si₃N₄/SiO₂/Si₃N₄ 박막위에 형성하였다. 단일 bifilar NiCr 히터가 내장된 변환기의 열감도는 공기 및 진공중에서 각각 약 14.0 ㎷/㎽ 및 54.0 ㎷/㎽였고, 교류-직류 전압 및 전류 변환 오차범위는 공기중에서 각각 약 ±0.60 ppm 및 ±0.11 ppm이었다. 변환기의 교류-직류 변환 정확도가 상용 3차원 구조의 다중접합 열전변환기의 것보다 훨씬 더 높게 개선되었으나, 시간에 따른 출력 열기전력의 변화는 비교적 높게 나타났다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.601-604
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• 2004

Precise position and attitude control of pico-satellite requires huge number of impulses of the order of 10$^{-6}$ Ns. MEMS solid rocket array is a promising propulsion system but the higher degree of miniaturization causes unreliable operation mainly due to quenching. In order to breakthrough this situation, a novel design of solid micro-rocket is proposed, which generates tiny impulses repetitively from a single rocket not from array. This unique micro-rocket is based on the utilization of quenching, which causes propellant reaction to sustain only in a small area. A test chip of a micro solid propellant tank and micro heater array is fabricated and ignition test is conducted. Obtained results show the feasibility of this concept and future direction of this quenching-based propulsion is discussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.427-431
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• 2000

ITO (indium tin oxide) thin films on PET (polyethylene terephthalate) and glass substrates have been deposited by a dc magnetron sputtering without heat treatments such as substrate heater and post heat treatment. Each sputtering parameter during the sputtering deposition is an important factor for the high quality of ITO thin films deposited on polymeric substrate. Particularly, the material, electrical and optical properties of as-deposited ITO oxide films are dominated by sputtering power, oxygen partial pressure and films thickness. As the experimental results, the XRD patters of ITO films are influenced by sputtering power and pressure. As the power and pressure are increased, (411) peak is grown suddenly. the electrical resistivity is also increased, as the sputteing power and pressure are increased. Transmittance of ITO thin films in visible light ranges is lowered with increasing the sputtering power and film thickness. Reflectance of ITO films in infia-red region is decreased, as the power and pressure is increased.

• 한국재료학회지
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• 제24권10호
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• pp.532-537
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• 2014

In this study, highly sensitive hydrogen micro gas sensors of the multi-layer and micro-heater type were designed and fabricated using the micro electro mechanical system (MEMS) process and palladium catalytic metal. The dimensions of the fabricated hydrogen gas sensor were about $5mm{\times}4mm$ and the sensing layer of palladium metal was deposited in the middle of the device. The sensing palladium films were modified to be nano-honeycomb and nano-hemisphere structures using an anodic aluminum oxide (AAO) template and nano-sized polystyrene beads, respectively. The sensitivities (Rs), which are the ratio of the relative resistance were significantly improved and reached levels of 0.783% and 1.045 % with 2,000 ppm H2 at $70^{\circ}C$ for nano-honeycomb and nano-hemisphere structured Pd films, respectively, on the other hand, the sensitivity was 0.638% for the plain Pd thin film. The improvement of sensitivities for the nano-honeycomb and nano-hemisphere structured Pd films with respect to the plain Pd-thin film was thought to be due to the nanoporous surface topographies of AAO and nano-sized polystyrene beads.

• E2M - 전기 전자와 첨단 소재
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• 제8권6호
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• pp.699-707
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• 1995

The material that is both conductive in electricity and transparent to the visible ray is called transparent conducting thin film. It has many fields of application such as Solar Cell, Liquid Crystal display, Vidicon on T.V, transparent electrical heater, selective optical filter, and a optical electric device , etc. In the recent papers on several TCO( transparent conducting oxide ) material, the study is mainly focusing on ITO(indium tin oxide) because ITO shows good results on both optical and electrical properties. Nowaday, in the development of LCD(Liquid Crystal display), the low temperature process to reduce the production cost and to deposit ITO on polymer substrate (or low melting substrate) has been demanded. In this study, we prepared indium tin oxide(ITO) by a cylindrical DC magnetron sputtering with Indium-tin (9:1) alloy target instead of indium-tin oxide target. The resistivity of the film deposited in oxygen partial pressure of 5% and substrate temperature of 140.deg. C. is 1.6*10$\^$-4/.ohm..cm with 85% optical transmission in viaible ray.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계합동학술대회 논문집
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• pp.197-201
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• 2002

This paper presents optimized design, fabrication and thermal characteristics of micro-heaters for thermal MEMS (micro electro mechanical system) applications using SOI and trench structures. The micro-heaters are based on a thermal measurement principle and contains thermal isolation regions of 10 ${\mu}m$-thick Si membranes consisting of oxide-filled trenches in the SOI membrane rim. The micro-heaters were fabricated with Pt-RTD on the same substrate via MgO buff layer between Pt thin-film and $SiO_2$ layer. The thermal characteristics of micro-heater with trench-free SOI membrane structure was $280^{\circ}C$ at input power 0.9 W; in the presence of 10 trenches, it was $580^{\circ}C$ due to reduction of the external thermal loss. Therefore, a micro-heater with trenches in SOI membrane rim structure provides a powerful and versatile alternative technology for enhancing the performance of micro-thermal sensors and actuators.

• 센서학회지
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• 제8권2호
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• pp.115-123
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• 1999

PSG(800nm)/$Si_3N_4$ (150nm)로 구성된 유전체 membrane 윗면에 heater와 감지전극을 등일면상에 동시에 형성하였다. 제작된 소자의 전체 면적은 $3.78{\times}3.78mm^2$이고, diaphragm의 면적은 $1.5{\times}1.5mm^2$이며, 감지막치 면적은 $0.24{\times}0.24mm^2$였다. 그리고 diaphragm내의 열분포 분석을 유한요소법을 이용하여 수행하였으며, 실제로 제작된 소자의 열분포와 비교하였다. 소비전력은 동작온도 $350^{\circ}C$에서 약 85mW였다. Sn 금속막을 상온과 $232^{\circ}C$의 두 가지 기판온도에서 열증착하였고, 이를 $650^{\circ}C$의 산소분위기에서 3시간 열산화함으로써 $SnO_2$ 감지막을 형성하였다. 그리고 이를 SEM과 XRD로 특성을 분석하였다. 제작된 소자에 대해서 온도 및 습도에 대한 감지막의 영향 및 부탄가스에 대한 반응특성도 조사하였다.

• 공업화학
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• 제20권6호
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• pp.692-695
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• 2009

바닥의 전기난방 장치로 사용할 수 있는 오믹 줄 방전 현상을 이용하는 면상발열체 전극기술을 개발하였다. Super pure black의 탄소재료와 polyvinylidene fluoride의 고분자 재료를 이용하여 제조한 복합 전극 합제를 PET에 박막 도포하여 전극을 제조하였다. 전극에 대한 조성 첨가제로서 multi-walled carbon nanotube와 연옥 분말을 사용하였다. 개발한 면상발열체 전극의 비저항과 전극의 접착강도 및 전극의 강도에 대하여 연구하였다. 연옥 분말의 첨가는 비저항과 강도에 미치는 영향이 적었으며, carbon nanotube의 첨가는 전극의 비전도도와 경도를 향상하였다. 다양한 조성의 오믹 줄 방전 전극의 특성을 연구하였다.