• 월간 기계설비
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• s.310
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• pp.115-118
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• 2016

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.2
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• pp.57-62
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• 2003

Nano-bending method is presented to measure the Poisson's ratio of thinfilms for MEMS (Micro-Electro-Mechanical Systems) applicaiton. The douvle-ring specimen is designed and fabricated based on the surface micromachining process to facilitate the measurement of the Poisson's ratio. The Poisson's ratio can be obtained through analyzing the linear load-displacement relationship of the double ring specimen subjected to nano-indenter loading. The Present nano-bending mehod is an in-situ measurement approach due to the compatibility to the surface micromachining process. The Poisson's ratio is locally obtained at the location of the double ring specimen with micro dimension. To validate the nano-bending method, the Poisson's ratio of LPCVD (Low Pressure Chemical Vapor Deposition) poly-silicon with thickness of 2.3㎛ is investigated. Experimental results reveal that the Poisson's ratio of the poly-silicon film is 0.2569. The standard deviation of the nano-bending measurement for the stiffness of double ring specimens is 2.66%.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.7
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• pp.777-787
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• 2012

The transient analysis for the output voltage of a piezoresistive microaccelerometer takes a relatively high computation time because at least two iterations are required to calculate the piezoresistive-structural coupled response at each time step. In this study, the high computational cost for calculating the transient output voltage is considerably reduced by an approach integrating the mode superposition method and the least square method. In the approach, data on static displacement and output voltage calculated by piezoresistive-structural coupled simulation for three acceleration inputs are used to develop a quadratic regression model, relating the output voltage to the displacement at a certain observation point. The transient output voltage is then approximated by a regression model using the displacement response cheaply calculated by the mode superposition method. A high-impact microaccelerometer subject to several types of acceleration inputs such as 100,000 G shock, sine, step, and square pulses are adopted as a numerical example to represent the efficiency and accuracy of the suggested approach.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.8
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• pp.731-736
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• 2016

Three-dimensional (3D) high-aspect-ratio (HAR) microstructures for biomedical applications (e.g., microneedle, microadhesive, etc.) are microfabricated using the hybrid ultraviolet (UV) lithography in which inclined, rotational, and reverse-side UV exposure processes are combined together. The inclined and rotational UV exposure processes are intended to fabricate tapered axisymmetric HAR microstructures; the reverse-side UV exposure process is designed to sharpen the end tip of the microstructures by suppressing the UV reflection on a bottom substrate which is inevitable in conventional UV lithography. Hybrid UV lithography involves fabricating 3D HAR microstructures with an epoxy-based negative photoresist, SU-8, using our customized UV exposure system. The effects of hybrid UV lithography parameters on the geometry of the 3D HAR microstructures (aspect ratio, radius of curvature of the end tip, etc.) are measured. The dependence of the end-tip shape on SU-8 soft-baking condition is also discussed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.1
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• pp.96-102
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• 1983

복사 형상계수를 계산하는 새롭고도 간단한 수치적 방법이 개발되었다. 유한선분 적분법은 윤 곽적분을 이용하며, 윤곽은 유한한 수의 선분으로 구성된 것으로 가정한다. 미소면적으로부터 유한면적까지의 복사 형상계수는 적분로 상의 절점의 좌표값에만 관계되며, 전자 계산기에 쉽게 프로그램 될 수 있다. 가우스의 적분을 이용하여 두 유한 면적사이의 복사 형상계수를 구한다. 미소 면적에서 원판까지, 두 개의 평행원판 사이, 및 두 개의 직사각형 사이의 복사 형상계수를 구하여 엄밀해와 비교하여 유한선분 적분법의 정확성이 우수함을 보였다. 단위구와 단위 정사 각형에서 타원체까지의 보가 형상계수의 값도 구하였다.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.88.1-88.1
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• 2005

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.124-129
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• 2000

The flow of liquid and vapor is investigated in trapezoidal grooves. The effect of variable shear stress along the interface of the liquid and vapor is studied for both co-current and counter-current flows. Velocity contours and results fur the friction are obtained for both trapezoidal grooves. An approximate relation that was previously utilized for the friction for the liquid was modified to obtain accurate agreement with the results for trapezoidal grooves.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.3
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• pp.880-886
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• 1991

본 연구에서는 이미 크랙전파의 제단계에 있는 평골재의 정유 크랙을 대상으 로, COD를 고정밀도로 측정하는 것을 주된 수단으로하여, 피로한도의 존재유무를 지배 하는 미소크랙의 정유구조를 상세히 밝히고자 한다. 또한 변형시교에 근거한 현상으 로만 알려져온 과소응력효과, coaxing효과를 크랙폐구현상의 관점에서 검토하여, 크랙 정유현상의 본질적인 이해를 얻고자 한다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.157-161
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• 1999

We investigated the effect of mechanical back side damage in Czochralski silicon wafer. The intensity of mechanical damage was evaluated by minority carrier recombination lifetime by laser excitation/microwave reflection photoconductance decay ($\mu$-PCD) technique, wet oxidation/preferential etching methods, near surface micro defect (NSMD) analysis, and X-ray section topography. The data indicate that the higher the mechanical damage intensity, the lower the minority carrier lifetime, and NSMD density increased proportionally, also correlated to the oxidation induced stacking fault (OISF) density. Thus, NSMD technique can be used separately from conventional etching method in OISF measurement.

• Journal of the KSME
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• v.43 no.6
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• pp.47-51
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• 2003

이 글에서는 전자 패키지 열적.기계적 신뢰성 평가 기술의 현황과, 전자 패키지의 신뢰성 설계를 위한 피로 실험, 미소 변형측정, 유한요소 해석을 통한 파손 해석 등의 관련 기술들을 소개한다.