• Proceedings of the Korean Reliability Society Conference
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• 2006.05a
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• pp.309-321
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• 2006

• Proceedings of the Korean Reliability Society Conference
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• 2005.06a
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• pp.83-105
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• 2005

• Journal of the Microelectronics and Packaging Society
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• v.15 no.2
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• pp.55-61
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• 2008

This paper shows quantitative reliability evaluations of a Bluetooth module through extending previous qualitative methods limited to structure reliability tests and solder joint reliability tests for Bluetooth modules. Accelerated Life Testing (ALT) of the modules using temperature difference in temperature cycling as an accelerated stress was conducted for quantitative reliability evaluation under field environment conditions. Lifetime distribution parameters were estimated using the failure times obtained through the ALT, and then Coffin-Manson model was implemented. Results of the ALT showed that the failure mode of the modules was open and the failure mechanisms are both crack and delamination. The ALT reproduced the failure mode and mechanisms of failed Bluetooth modules collected from the field. Further, a quantitative reliability evaluation method with respect to various temperature differences in temperature cycling was proposed in this paper. $B_{10}$ lifetime of the module for the temperature difference $70^{\circ}C$ using the proposed method would be estimated as about 4 years.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2007_2008
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• 2009

본 논문은 $SF_6$ 가스졀연차단기를 대체할 고체절연차단기(Solid Insulated Switchgear:SIS)의 기계적 신뢰성 평가에 대한 연구 결과이다. 최근 제정된 "25.8kV 가스 및 고체절연 친환경 개폐장치" 한전 구매규격에는 "Epoxy 고체절연물에 대한 기계적 신뢰성(수명)이 25년 이상"임을 보증할 수 있는 신뢰성 데이터를 제출해야 한다는 조항이 포함되어있다. 이에 개발된 고제절연차단기의 Epoxy 고체절연물에 대한 기계적 신뢰성(수명)이 25년 이상임을 보증할 수 있는 신뢰성 시험과 분석 기법에 대한 연구가 진행되었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.594-599
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• 2011

In this paper, the effect of the boundary conditions on the reliability and the cumulative distribution characteristics of the fatigue failure life is analyzed in a magnesium alloy AZ31. The boundary conditions are specimen thickness, stress ratio, and maximum fatigue load. The statistical data of the fatigue failure life are obtained by fatigue crack propagation tests under the detail conditions for each boundary condition. The 3-parameter Weibull distribution is used to analyze a statistical characteristics of the fatigue failure life in magnesium alloy AZ31. It is found that the statistical fatigue failure life is long in the case of a thicker specimen, a larger stress ratio, and a smaller maximum fatigue load. Under the opposite cases, the reliability on the fatigue failure life is rapidly dropped.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2089_2090
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• 2009

본 논문은 한전에서 사용되는 25.8kV 가스 절연 부하개폐기(이하 개폐기)에 대해 장기과통전시험, 부하전류 개폐 및 접점마모시험, 가스 기밀재 가속열화시험을 통해 신뢰성을 평가하였다. 국내 개폐기의 신뢰성 및 수명에 대한 척도를 평가한 결과, 모든 시료가 $B_{10}$ 수명 20년 이상을 보증할 수 있는 것으로 나타났다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.2
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• pp.172-180
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• 2016

A cubesat classified as a pico-satellite typically uses commercial-grade components that satisfy the vibration and thermal environmental specifications and goes into mission orbit even after undergoing minimum environment tests due to their lower cost and short development period. However, its reliability exposed to the physical environment such as on-orbit thermal vacuum for long periods cannot be assured under minimum tests criterion. In this paper, we have analysed the reliability and life prediction of the failure mechanisms of the cubesat mission board during its service life under the launch and on-orbit environment by using the sherlock software which has been widely used in automobile fields to predict the reliability of electronic devices.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.3
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• pp.907-915
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• 1991

본 연구에서는 피로 크랙 발생 및 파단수명의 통계학적 분포특성을 명확히 하 기 위해서 단축인장을 받고, 크랙 선단 곡율반경이 일정한 중앙 크랙을 가진 81개의 시험편을 사용하여 4개의 응력 레벨하에서 피로 시험을 행한후 많은 데이터들로 부터 피로크랙의 발생, 파단특성에 대한 신뢰성 있는 통계학적 확률특성을 제시하고, 이들 데이터를 활용하여 수명예측을 행해보고저 한다.

• Proceedings of the Korean Reliability Society Conference
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• 2006.05a
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• pp.149-157
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• 2006

에스컬레이터 스텝 및 수평보행기 팰릿의 가속수명시험 국제 기준인 5백만회 시험조건 및 하중조건의 등가 현장 수명에 대한 근거를 산출하였다. 업체 및 산기원의 시험 데이터로부터 Weibull 모델을 추정하여 분석한 결과 에스컬레이터 스텝 및 수평보행기 팰릿의 형상모수가 각각 2.4$\sim$2.6 및 2.7$\sim$2.8로 산출되었다. 이 형상모수를 이용하여 본 연구에서 대상으로 한 에스컬레이터 스텝 및 수평보행기 팰릿의 B$_{10}$ 수명이 각각의 목표 수명 7년과 6년을 보증할 수 있음을 확인하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.6
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• pp.1583-1591
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• 1990

Life prediction and residual life prediction of structures of machines are one of the most strongly world wide needed problems as requirement in the stage of slowly developing economy which comes after rapidly and highly developing stage. For the purpose of statistical life prediction, fatigue test was conducted under the 4 stress levels, and for each stress level, about 20 specimens are used. The statistical properties of crack growth parameter m and C in the fatigue crack growth law of da/dN=C(.DELTA.K)sup m/, and the relationship between m and C, and the statistical distribution pattern of fatigue crack growth rate can be obtained by experimental results.