• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.169-173
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• 1997

In this paper, auto measuring system for evaluating sensing reliability of infrared temperature sensors is developed. A developed system is composed of temperature controller, measuring sysytem and operating S/W. A constant temperature control of a chamber is accomplished by multi-heater using PI control. It is shown that the control resulte of temperature are well followed to the desired temperature value. The developed untegrated measuring system will increase reliability and productivity of products.

• 한국신뢰성학회지:신뢰성응용연구
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• 제12권4호
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• pp.275-285
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• 2012

This paper presents a changes of luminescence property for converted white LEDs with the commercially available silicate phosphor. If silicate phosphor's quantity increase step by step. luminescence property will be changing. we analyze luminescence property for these change and carry out the high temperature aging test for 7,000 hours, the high temperature and humidity aging test for 7,000 hours for reliability. LED degradation not only results in reduced light output but also in color changes. so we monitor correlated color temperature (CCT), chromaticity coordinates(x, y) and spectrum intensity. Those results suggest that humidity factor more bad effect in color changes than temperature factor and Lighting quality is related with quantity of phosphor.

• 보존과학연구
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• 통권31호
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• pp.59-68
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• 2010

Cultural heritages are damaged by surrounding several environmental factors. Main factors are temperature, humidity, light, atmosphere and indoor pollutant, organism, etc. Therefore, to prevent damage of cultural heritage from such environmental factor, conservation environment monitoring becomes more important. Indicator is one of the simple method for environment monitoring. It can be used without expensive and complex equipments. However, it should be performed scientific examination for application to cultural heritage. In this study, some Temperature Indicators were chosen and reliability assessment was carried out for application to cultural heritage. Brightness($L^*$) is selected for reliability assessment factor. As a result of lab test, Temperature Indicators were not influenced greatly in humidity change. When they were exposed to setting temperature, the color was changed in setting temperature area and ${\pm}2^{\circ}C$ part of setting temperature. Especially brightness value was high in setting temperature area. Also, Temperature Indicators were stabilized after about 16 minutes when were exposed to temperature difference of $10^{\circ}C$ and when temperature difference with exposure environment is smaller, stabilization time shortened. Therefore, it is a possible to confirm that selected Temperature Indicator is reliable product through measurement of color difference value and naked eye observation.

• International Journal of Reliability and Applications
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• 제1권1호
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• pp.89-104
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• 2000

Accelerated testing consists of a variety of test methods for shortening the life of products or hastening the degradation of their performance. This paper presents practical, modern statistical methods for evaluating the reliability of Nickel-Cadmium batteries at their design temperature of 2$0^{\circ}C$ by accelerated life test. Batteries have been life tested at three high temperature conditions, 50, 60, 7$0^{\circ}C$, respectively to yield failures quickly. The failures have been observed and judged by means of charge and discharge current integration. Analyses of life data from those conditions resulted in the Weibull distribution, which has been verified on the ground of the Kolmogorov-smirnov test and the pairwise t-test. Life data are modeled according to the Arrhenius life-temperature relationship. The mean life of tested batteries is assessed at about 590 cycles, and the activation energy of this chemical reaction is concluded to be 0.39eV as results. This study provides procedures for estimating the reliability of batteries in a short period, which has little been possible in domestic industries. The results can be applied in many fields such as proof testing, acceptance testing, and estimating assurance periods.

• 한국신뢰성학회지:신뢰성응용연구
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• 제14권3호
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• pp.203-207
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• 2014

Electrodeless lamp is famous for its long life. But its reliability is dependent not only on electrodes but also on materials and structures. To evaluate end product's reliability, we studied high temperature durability by $60^{\circ}C$, $75^{\circ}C$ and $90^{\circ}C$ temperature tests, and predicted failure times by an exponential model through regression analysis. However, the test showed that temperature does not affect degradation of electrodeless lamps. Their luminous outputs degrade during the early time of the test (till 250 hours) and then converge to a saturation points. Also, '410nm ~ 530nm' spectrum degrades more than other spectra.

• 한국항공우주학회지
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• 제35권3호
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• pp.268-274
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• 2007

일반적으로 로켓과 위성 전자 회로 설계 단계에서 전자 소자의 신뢰도를 높이기 위해 소자의 작동온도를 낮추는 방법이 많이 사용된다. 본 논문에서는 소자 온도뿐 아니라 활성화에너지가 전자 장비 신뢰도에 미치는 영향에 대해 상세히 분석하였는데 실제 소자의 온도보다는 소자의 활성화에너지가 신뢰도에 훨씬 많은 영향을 끼치는 것으로 분석되었으며 이에 대한 분석결과를 정량적으로 기술하였다. 또한 PCB에 소자 배치 시 신뢰도를 높이기 위한 소자 배치 방법과 이에 따른 신뢰도 향상 결과에 대해서도 기술하였다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제11권3호
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• pp.235-244
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• 2011

Hydraulic hose assemblies deliver a fluid power in various oil pressure equipment such as construction machinery, automobile, aircraft, industrial machinery, machine tools and machinery for ships. Also, they are widely used as pipes in oil pressure circuit. When we estimate their lifetime, it is essential to conduct an accelerated life test by choosing the factor that suits the usage condition of the test object since traditional test method for estimating lifetime under the influence of various external factors incurs hardship in terms of time and expenses. The objective of this study is to propose an acceleration model that takes both temperature and pressure without flexing condition into consideration. The lifetime is estimated by applying the proposed temperature-nonthermal acceleration model to the test data. And we compare the proposed temperature-nonthermal acceleration model and the accelerated life equation suggested by John(1994).

• 조명전기설비학회논문지
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• 제29권4호
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• pp.1-10
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• 2015

The light emitting diodes(LED) package of new structure is proposed to promote the reliability and lifespan by maximize heat dissipation occurred on the chip. We designed and fabricated the LED packages mixing the advantages of chip on board(COB) based on conventional metal printed circuit board(PCB) and the merits of Si sub-mount using base as a substrate. The proposed LED package samples were selected for the superior efficiency of the material through the sealant properties, chip characteristics, and phosphor properties evaluations. Reliability test was conducted the thermal shock test and flux rate according to the usage time at room temperature, high-temperature operation, high-temperature operation, high-temperature storage, low-temperature storage, high-temperature and high-humidity storage. Reliability test result, the average flux rate was maintained at 97.04% for each items. Thus, the Si sub-mount based LED package is expected to be applicable to high power down-light type LED light sources.

• 전력전자학회논문지
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• 제27권6호
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• pp.535-540
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• 2022

DC-link capacitors are reliability-critical components in a photovoltaic (PV) inverter. Typically, the lifetime of a DC-link capacitor is evaluated by considering the voltage and hot-spot temperature of the capacitor under the specific operating condition of the PV inverter. However, the output of the PV inverter is determined by solar irradiation and ambient temperature, which vary with the seasons; accordingly, the hot-spot temperature of the capacitor also changes. Therefore, the mission profile of the PV system should be considered to effectively evaluate the reliability of the DC-link capacitor. In this study, the reliability of the DC-link capacitor of a three-level NPC inverter is comparatively analyzed with and without considering the mission profiles of the PV system, where two mission profiles recorded in Arizona and Iza are considered. The accumulated damage of the DC-link capacitor is calculated based on the lifetime model by analyzing its thermal loading. Afterward, a reliability evaluation of the DC-link capacitor is performed at the component level and then at the system level by considering all capacitors by means of Monte Carlo analysis. Results reveal the importance of performing a mission-profile-based reliability evaluation during the design of high-reliability PV inverters to achieve the target reliability performance.

• 마이크로전자및패키징학회지
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• 제15권2호
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• pp.55-61
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• 2008

본 논문은 블루투스 모듈의 구조 및 솔더접합부에 대한 신뢰성 평가에 국한된 기존의 방법을 확장하여 정량적인 신뢰성 평가를 수행한 결과를 나타낸다. Field 환경조건에서의 정량적인 신뢰성 평가를 위해, 온도 싸이클링(temperature/thermal cycling)에서의 온도차를 가속스트레스로 선정하여 가속수명시험을 실시하였다. 가속수명시험을 통해 구한 고장시간 데이터들을 이용하여 수명분포 매개변수들을 추정하고 코핀-만슨(Coffin-Manson) 모델을 이용하였다. 가속수명시험을 수행한 결과, 블루투스 모듈의 고장모드는 Open, 고장메커니즘은 크랙(Crack)과 박리(Delamination)였다. Field에서 수거한 고장품들의 고장모드와 고장메커니즘이 가속수명시험을 통해 재현되었다. 또한 본 논문에서 블루투스 모듈이 Field에서 받을 수 있는 온도 싸이클링에서의 다양한 온도차에 대한 정량적인 수명을 예측할 수 있는 방법이 제시되었다. 제안된 방법을 이용하여 온도차 $70^{\circ}C$를 받고 있는 블루투스 모듈의 $B_{10}$ 수명은 약 4년으로 추정되었다.