• 품질경영학회지
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• 제21권1호
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• pp.108-120
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• 1993

In this article an economic life test sampling plan is considered for repairable products when the products in each lot have the same interfailure time distribution, but the mean time between failure (MTBF) of a lot varies from lot to lot according to a known prior distribution. A cost model is constructed which consists of test cost, accept cost, and reject cost. Determination of the optimal plan which minimizes the expected average cost per lot is discussed. Numerical examples are presented to illustrate the use of the proposed sampling plans and sensitivity analyses for parameters of the prior distribution are performed.

• 대한기계학회논문집A
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• 제29권7호
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• pp.921-929
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• 2005

This paper presents an accelerated life test for burnout of tungsten filament of incandescent lamp. From failure analyses of field samples, it is shown that their root causes are local heating or hot spots in the filament caused by tungsten evaporation and wire sag. Finite element analysis is performed to evaluate the effect of vibration and impact for burnout, but any points of stress concentration or structural weakness are not found in the sample. To estimate the burnout life of lamp, an accelerated life test is planned by using quality function deployment and fractional factorial design, where voltage, vibration, and temperature are selected as accelerating variables. We assumed that Weibull lifetime distribution and a generalized linear model of life-stress relationship hold through goodness of fit test and test for common shape parameter of the distribution. Using accelerated life testing software, we estimated the common shape parameter of Weibull distribution, life-stress relationship, and accelerating factor.

• 전기학회논문지P
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• 제64권4호
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• pp.256-260
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• 2015

In this paper, achieved rise temperature distribution about degradation phenomenon of 24 MVA distribution cast resin transformer using CFD(Computational Fluid Dynamics). Usually, life of transformer is depended on temperature distribution of specification region than thermal special quality of transformer interior. Specially, life of transformer by decline of dielectric strength decreases rapidly in case rise by strangeness transformer interior hot spot temperature value permits. Because calculating high-voltage(HV) winding and low-voltage(LV) winding of cast resin transformer and Joule's loss of core for improvement these life, forecasted heat source, and HV winding and LV winding of cast transformer rise temperature distribution of core for supply of electric power and temperature distribution of highest point on the basis of the results. Also, calculated temperature rise limit of cast resin transformer and permission maximum temperature using analysis by electromagnetic heat source. Calculated and forecasted rise temperature distribution by heat source of thermal analysis with calculated result.

• 조명전기설비학회논문지
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• 제22권10호
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• pp.49-55
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• 2008

본 논문은 확률분포를 이용하여 전력설비의 기대여명을 산출하는 방법을 제안한다. 전력설비의 기대여명이란 해당 설비의 잔존수명으로, 기대여명은 전력시스템의 보수계획, 설비교체계획, 신뢰도 평가에 유용하게 이용될 수 있다. 본 논문에서는 각 운전년수별로 향후 운전가능년수에 대한 누적확률을 계산하고, 계산한 누적확률로 누적확률분포함수모델의 모수를 결정한 후, 모델함수의 평균값을 구하여 기대여명을 산정한다. 제안한 방법에서는 정립한 누적확률분포함수모델을 이용하여 기대여명 뿐만 아니라, 향후 특정 운전년수에 이르기 위한 기대확률까지도 쉽게 구할 수 있다. 제안한 방법은 우리나라 복합화력 발전소 발전기의 기대여명 추정에 적용하여 그 효용성을 입증하였다.

• 산경연구논집
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• 제10권10호
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• pp.7-13
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• 2019

Purpose - This study is to verify the mediating effect of voluntariness in retirement and the moderating effects of leisure life to examine which parts of later life preparations have influence on the retired life. Research design, data, and methodology - In this study, the 6^th Korean Retirement and Income Study was conducted on 5,254 members of households with householders over the age of 50. To examine the relationship between later life preparation and retired life, this study used personal data based on the serial number of the household members. Results - First, physical preparation for later life had a positive influence on retired life satisfaction among retirement satisfaction. People showed higher retired life satisfaction. Secondly, physical preparation for later life had a positive influence on satisfaction over relationship after retirement among retirement satisfaction. People showed higher satisfaction over relationship after retirement when they were more physically prepared for later life. Conclusions - In particular, leisure life had a mediating effect for the influence of physical preparation for later life on the retired life. Also, leisure life and physical preparation for later life showed a close influencing relationship. People showed active leisure life and higher retired life satisfaction when they were more physically prepared for later life.

• 한국강구조학회 논문집
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• 제10권1호통권34호
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• pp.37-45
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• 1998

기계 및 구조물의 안전성과 신뢰성 평가를 위하여 금속재료의 피로강도 데이터베이스 시스템을 구축하고, 이를 이용하여 금속재료의 피로수명 분포특성을 검토하였다. 종속도를 이용하여 구성한 관계형 피로강도 데이터베이스 시스템은 일련의 데이터 관리 및 해석작업을 효율적으로 수행하였다. 또한 Robust 방법과 보상오차함수(complementary error function)를 이용한 3-파라미터 Weibull분포의 파라미터 추정법 및 비파손확률를 검토하기 위하여 제안된 새로운 기준식의 타당성을 검토하였다. 조합분포모델을 이용하여 부하응력비와 Weibull분포의 파라미터 항으로 나타낸 피로수명 분포식은 탄소강의 P-R-N 특성을 해석함에 있어서 좋은 결과를 보였다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제8권2호
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• pp.75-85
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• 2008

In this paper, we compared domestic with foreign pilot lamps installed on the instrument board or electronic modules (car audio, air-conditional system, etc.) of an automotive vehicle by an accelerated life test in order to estimate the life of domestic pilot lamps. An accelerated life test method was developed and the relation of the life and voltage stress was analyzed. The main results are as follows; i) $B_{10}$ life of pilot lamp is above 5,000 hours, vehicle travel time for 10 years. ii) the life of domestic pilot lamp is longer than that of foreign thing. iii) the life distribution of domestic pilot lamp is wider than that of foreign thing. iv) it is possible to promote import replacement of automobile pilot lamp.

• KEPCO Journal on Electric Power and Energy
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• 제7권2호
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• pp.241-248
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• 2021

High cycle fatigue life for the cables with two different types of clamps is estimated comparatively through acceleration testing. The high cycle fatigue fracture of overhead lines is caused mainly by the aeolian vibration which is induced by vortex shedding. It is necessary to manage the integrity of cables continuedly considering that the aeolian vibration is unavoidable since it occurs in steady and relatively low wind velocity. Two types of clamps which are largely used for overhead lines of the distribution grids are selected and failure data are obtained by step stress testing with a electrodynamic shaker with them. The inverse power law is assumed to describe the stress-life relationship and the fatigue limit at any specified life is supposed to follow Weibull distribution. The life of the cable is defined as the number of cycles to the time that one of strands is completely broken. Finally, the fatigue limits of the cables with two clamp types are estimated at the reference life of 500 Mcycles and compared each other based on a bending vibration amplitude.

• 대한지리학회지
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• 제36권3호
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• pp.258-277
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• 2001

농협 연쇄점을 정보화로 인한 商的 유통의 합리화와 재고 집약형 대규모 물류센터의 다극화로 물적 유통 의 집약화가 이루어져 유통의 효율성을 높였고, 수송도 외부수주로 이루어지고 있다. 이에 따라 생활용품과 농산물의 배송방식은 각각 루트배송과 정시 일괄배송으로 상품의 특성에 따라 그 배송권이 형성되었다. 한편 상품 판매활동에 의한 공간적 특성은 답작농업의 발달과 서비스업 취업 정도에 따라 판매 상품류의 구성이 결정된다는 점이 밝혀졌다. 그러나 일상생왈 상품인 가공 식품류와 잡화류는 농협 연쇄점이 입지한 지역유형에 영향을 받지 않고 판매된다는 점이 규명되었다.

• 한국포장학회지
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• 제26권3호
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• pp.165-171
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• 2020

유통과정에서 균질한 저온을 유지하는 것은 식품의 유통기한을 결정하는 가장 중요한 요소 중 하나인 미생물 증식을 억제하는 핵심 기술이다. 신선수산물의 전과정에서 정확하고 적절한 온도관리가 보장되었을 때 높은 품질의 신선 제품을 소비자에게 공급할 수 있다. 이 논문은 슈퍼칠링 신선수산식품의 상업성을 확인하기 위하여 포장된 신선 광어(Paralichthys Olivaceus) 의 유통기한을 연구한 것이다. 유통기한 측정을 위하여 중량, 대장균 등 세균수, pH, 관능검사, 색상, 휘발성 염기질소 등이 조사되었다. 연구결과, 휘발성염기질소를 기준으로 슈퍼칠링 온도(0±1℃)에서의 유통기한이 6일인데 비하여 일반 냉장온도 (8±2℃)의 경우 1일에 불과하여 슈퍼칠링 유통의 가능성을 보여주었다. 상업화 추진을 위해서는 소비자 신뢰도를 높이고 경제성을 향상시킬 수 있도록 슈퍼칠링 기법과 포장시스템에 대한 추가적인 포장방법 연구가 필요한 것으로 사료된다.