• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1857-1862
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• 2008

Resonant frequency tuning of micro devices is essential to achieve performance uniformity and high sensitivity. Previously reported frequency tuning methods using electrostatic force or mass deposition are not directly applicable to non-conducting polymer devices and have limitations such as dielectric breakdown or low tunable bandwidth. In this paper, thermally frequency-tunable microactuators with poly-dimethylsiloxane membranes are proposed. Permanent and/or nonpermanent frequency tunings are possible using a simple temperature control of the device. Resonant frequency and Q-factor variations of devices according to temperature change were studied using a micro heater and laser Doppler vibrometer. The initial resonant frequencies determined by polymer curing and hardening temperatures are reversibly tuned by thermal cycles. The measured resonant frequency of 9.7 kHz was tuned up by ${\sim}25%$ and Q-factor was increased from 14.5 to 27 as the micro heater voltage increased from 0 to 70 V.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.844-847
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• 2001

The application of laser direct etching has been discussed, and believed that the process is a very powerful method for micro machining. This study is focused on the micro patterning technology using laser direct etching process with no chemical damage of the material surface. A new introduced concept of energy synergy effect for surface micro machining is the combination of chemically ion reaction and laser thermal process. The etchant can't etch the material in room temperature, and used Ar laser has not power enough to machine. But, the machining is occurred in local area of the material by the combined energy. Using this process, the material is especially prevented from chemical damage for electric property. We have tested this new concept, and achieved a line with $1{mu}m$ width. The Ar laser with 488nm wavelength was used. The material was Si(100) wafer, and etchant is KOH solution. The application and flexibility of this process is in great hopes for MEMS structures and fabrication of the micro electric device parts.

• 제어로봇시스템학회논문지
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• 제12궈1호
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• pp.85-92
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• 2006

A new silicon micro flow sensor with multiple temperature sensing elements was proposed and fabricated in considering wide range flow velocity measuring device. Thermal mass flow sensor measures the asymmetry of temperature profile around the heater which is modulated by the fluid flow. A micro mass flow sensor was normally composed of a central heater and a pair of temperature sensing elements around it. A new 2-D wide range micro flow sensor structure with three pairs of temperature sensing elements and a central heater was proposed and numerically simulated by Finite Difference Formulation to confirm the feasibility of the wide flow range sensor structure. To confirm the simulation result, the new flow sensor was fabricated on silicon substrate and the basic flow sensing properties of the sensor were measured.

• 대한기계학회논문집B
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• 제35권11호
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• pp.1133-1137
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• 2011

마이크로 수준에서의 온도측정을 위하여 유리 피펫 기반의 프로브형 온도센서를 제작하였다. 이를 이용하여 정밀도 ${\pm}$ 0.1 K 를 가지는 온도측정 보정 실험을 수행하였다. 본 연구에서 제작한 방식은 저온의 용융점을 갖는 솔더합금(Sn)을 피펫에 내부에 주입하고 외부에 니켈(Ni) 코팅을 하여 열전대를제작함으로써 저비용의 프로브형 온도센서를 구현하였다. 제작된 센서 팁 끝단의 지름은 5 Am 에서 30 Am 로 피펫을 가열하여 당기는 방식으로 프로브 끝단의 크기를 조절하였다. 제작된 온도센서는 챔버내에서 정밀하게 제어된 온도 조절기를 사용하여 보정하였으며, 이를 통하여 얻어진 열전계수의 범위는 8.46 에서 $8.86{\mu}V$/K 의 값을 얻었다. 이를 이용하면 MEMS 소자, 세포, 티슈 등의 바이오 소재의 온도 및 열특성 측정용 프로브로 활용할 수 있을 것으로 생각된다.

• 전기학회논문지
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• 제57권9호
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• pp.1594-1598
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• 2008

The ionic air pump can be used towards the thermal management of micro-electronic devices, since the size of pump can be reduced to micrometer orders. In addition, an air pump allows air flow control and generation with low noise and no moving parts. These ideal characteristics of the pump give rise to variety applications. However, all of these applications would benefit from maximizing the flow velocities of the pumps. In this study a surface discharge type air pump, with a third electrode, has been investigated by focusing on elevating the wind velocity and efficiency. As a result, the enhanced ionic wind velocity could be obtained with the third electrode of the proposed air pump.

• 비파괴검사학회지
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• 제37권2호
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• pp.106-114
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• 2017

This paper presents an automated subsurface micro void detection technique based on pulsed infrared thermography for inspecting epoxy molding compounds (EMC) used in electronic device packaging. Subsurface micro voids are first detected and visualized by extracting a lock-in amplitude image from raw thermal images. Binary imaging follows to achieve better visualization of subsurface micro voids. A median filter is then applied for removing sparse noise components. The performance of the proposed technique is tested using 36 EMC samples, which have subsurface (below $150{\mu}m{\sim}300{\mu}m$ from the inspection surface) micro voids ($150{\mu}m{\sim}300{\mu}m$ in diameter). The experimental results show that the subsurface micro voids can be successfully detected without causing any damage to the EMC samples, making it suitable for automated online inspection.

• 전기학회논문지
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• 제58권6호
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• pp.1093-1099
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• 2009

Alternative energy sources such as renewable energy like solar power systems, wind power systems, or fuel cell power systems has been the rising issue in the electrical power system. This paper discusses an economic study analysis of fuel cells in the korean electricity market. It includes the basic concept of a fuel cell and the korean electricity market. It also describes the need of renewable energy and how the fuel cell is connected with the local grid. This paper shows the impact of production and recovering thermal energy of a grid-connected fuel cell power system. The profit maximization approach has been structured including electrical power trade with the local grid and heat trade within the micro-grid. The strategies are evaluated using a local load that uses electric and thermal power which has different patterns between summer and winter periods. The solution algorithm is not newly developed one, but is solved by an application called GAMS. Results indicate the need and usefulness of a fuel cell power system.

• 분석과학
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• 제5권4호
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• pp.359-366
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• 1992

본 논문은 마이크로 Raman 분광분석법을 이용하여 국부적 열산화 후 실리콘 표면에 유입되는 스트레스를 평가한 것이다. 국부적 열산화 후 실리콘 표면에 유입되는 스트레스는 실리콘 산화막과 active 영역의 경계 부분에서 최대치를 나타내었다. Active 영역의 크기가 작아질수록 스트레스량은 증가하며, 이는 스트레스가 active 영역의 크기에 의존함을 보여 주는 것이다. 또한, active 영역이 $0.45{\mu}m$인 세 가지 소자 분리 공정, A, B, moB를 평가한 결과 moB 공정의 스트레스 값이 가장 작았으며, 새부리 효과도 가장 작았다.

• 한국ITS학회 논문지
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• 제7권5호
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• pp.97-105
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• 2008

반도체 공정의 미세화 및 마이크로 시스템 기술의 발전 그리고 소형 무선PAN 및 이동통신 장치들의 급증으로 인하여 전자부품들의 소형화와 직접화에 대한 요구가 지속적으로 증가되고 있다. 본 연구에서는 휴대형 무선PAN 및 이동통신용 전자회로 설계에 다양한 목적으로 널리 사용되고 있는 기저대역의 수동소자들 중 미세 커패시터의 안정성과 전기적 특성을 확보하기 위하여, 유전체인 AIN을 사용하여 MIM구조로 제작된 미세 박막 커패시터 소자의 전기적인 특성을 분석하고 기저대역에서의 성능을 평가한다. 또한 제작된 미세 박막형 커패시터의 용량제어 방법을 제시함으로서 기저대역에서 범용으로 사용할 수 있는 미세 박막 커패시터의 모델을 제시하고자 한다. 또한, 주파수 대역에 따른 MIM구조의 AIN 커패시터 특성을 분석함으로서 향후 임베디드 소자와 집적화를 위한 고정밀의 미세수동 소자로서의 활용방안을 제시하고자한다.

• 설비공학논문집
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• 제22권10호
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• pp.679-686
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• 2010

A proprietary device is adopted to break out the membrane of cell in the rigid polyurethane foam. As it is known, the membrane of cell is hardly tearing-off thoroughly in a mechanical way due to both its elastic characteristic and micro sized pores. In this study, a novel experimental approach is introduced to burst out all gases inside the cells of the rigid polyurethane foam by abrasively grinding micro-cells completely into fine powder. The biggest advantage of this approach is to be capable of releasing all gases out from the cell even in the micro pores. As clearly reflected from the repeatability, the accuracy of the result is highly improved and high confidence in the data sets as well. For the measurements of not only gas composition but partial pressure for each gas simultaneously as well, a precision gas mass spectrometer is used in-line directly to the abrasive grinding device. To control the starting point of the polyurethane foam, all samples were prepared on site in the laboratory. Manufactured time is one of the most critical factors in characterization of cell gas composition because it is known that one of gas composition, especially, carbon dioxide, is diffused out dramatically in a short period of time as soon as it is foamed.