• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2845-2849
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• 2008

Long Term Asset Management(LTAM) means a plan developed by using LCM(Life Cycle Management) process for optimum life cycle management of significant plant assets at each plant across the fleet. As a part of development of LTAM Strategies on nuclear turbines, a method so as to determine the future failure rates for low pressure turbine facilities at a nuclear plant was studied and developed by using both plant specific and industry-wide performance data. INPO's EPIX data were analyzed and some failure rate evaluation values considering preventive maintenance practices were calculated by using EPRI's PM Basis software. As the result, failure rate functions applicable to a priori and a posteriori replacement of low pressure turbines at a nuclear plant were developed and utilized in an assessment of economics of LCM alternatives on the nuclear turbine facilities in the respects of 40-year and 60-year operation bases.

• Communications for Statistical Applications and Methods
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• 제16권5호
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• pp.871-880
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• 2009

Recently, there has been much development on burn-in models in reliability area. Especially, the previous burn-in models have been extended to more general cases. For example, (i) burn-in procedures for repairable systems have been developed (ii) an extended assumption on the failure rate of the system has been proposed and (iii) a stochastic model for burn-in procedure in accelerated environment has been developed. In this paper, recent extensions and advances in burn-in models are introduced and some issues to be considered in the future study are discussed.

• 한국산학기술학회논문지
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• 제21권7호
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• pp.428-434
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• 2020

일회성 무기체계는 대기 상태로 있다가 단 한 번의 임무를 수행한 이 후 폐기되는 특성에 따라 높은 신뢰도를 요구받는다. 유도탄은 일회성 무기체계로써 특성상 저장 상태로 수명의 대부분을 보내고, 임무수행을 위한 운용시간은 짧기때문에 임무성공률이 아닌 저장 신뢰도로 분석해야 한다. 유도탄의 신뢰도를 분석할 때에 어떠한 방법을 사용하는지에 따라 그 결과는 달라질 수 있으며, 고장자료와 함께 포함되는 우측 관측중단자료의 비율에 따라서도 차이가 발생할 수 있다. 본 연구는 공군의 OO유도탄을 대상으로 미래의 고장률을 보다 정확하게 예측하기 위한 방법을 제시하고자 작성하였다. 제시하는 방법은 먼저 평균 고장시간(MTTF: Mean Time To Failure, 이하 MTTF)을 적용한 모델과 고장 간 평균시간(MTBF: Mean Time Between Failure, 이하 MTBF)을 적용한 모델로 고장률을 예측하고, 두 모델 중 실제 고장률과 차이가 작은 모델을 선택한다. 선택한 모델로 고장자료와 함께 포함되는 우측 관측중단자료의 비율을 달리하여 고장률을 예측하고, 실제 고장률과의 차이가 최소화되는 비율을 찾는다. 실제 자료를 바탕으로 제안한 비율과 현재 검사 비율의 비교를 통해 제안한 비율이 미래 고장률을 예측하기에 더 적합함을 보였다.

• 한국산학기술학회논문지
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• 제21권2호
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• pp.366-372
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• 2020

육군에서 사용하는 로켓탄은 생산되고 나서 단 한 번의 임무수행으로 소모되는 원샷 무기체계로 높은 신뢰성을 요구한다. 원샷 무기체계인 로켓탄의 신뢰성 분석을 위해서는 이미 발생한 고장 자료를 활용하거나 아직 고장이 발생하지 않은 비고장 자료를 활용할 수 있다. 그러나 고장 자료만으로 실시할 경우 수명분포가 과소 추정될 수 있고, 비고장 자료를 모두 포함할 경우 과대 추정되어 실제 수명분포와 상당한 오차가 발생할 수 있으며, 이 수명에 대한 오차는 로켓탄의 조기폐기나 전수조사로 인한 비용을 증가시킬 수 있다. 육군은 이러한 문제 때문에 비고장 자료에서 샘플 수를 정하여 고장 자료와 함께 신뢰성 분석을 실시하고 있으나 실제 고장률을 예측하는데 한계가 있다. 본 연구는 이를 해결하기 위해 육군의 000다연장 로켓탄을 대상으로 비고장 자료를 비율별로 샘플링하여 수명분포의 오차가 최소화되는 비율을 찾는 샘플링 절차에 대해 새롭게 제안하고 이를 바탕으로 미래 고장률을 예측하였다. 제안한 비율별 샘플링 방법과 현재 사용하는 샘플링 방법의 비교를 통해 제안한 샘플링 방법이 미래 고장률을 더 정확하게 예측할 수 있음을 보였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 추계학술대회 논문집
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• pp.485-486
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• 2006

• KEPCO Journal on Electric Power and Energy
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• 제8권2호
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• pp.61-68
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• 2022

In this paper, the change history of various types of MV (Medium Voltage) cables was investigated. In addition, the statistical life expectancy of each type was calculated by using the operation data and the failure data. For cut-off year, 10 years was applied, and realistically applicable statistical life expectancy was calculated by correcting the cause of failure entered by mistake. The life expectancy of FR-CNCO-W was calculated as 51.2 years, CNCV-W 38.1 years, and CNCV 31.4 years and the overall average is 33.8 years. Currently, the life expectancy of TR CNCV-W is 29.4 years, but it is estimated that the lifespan will be extended if failure data is accumulated. As a result, it is expected that life expectancy results can be applied to Asset Management System (AMS) in the future.

• 유통과학연구
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• 제3권1호
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• pp.23-42
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• 2005

The service offer expectation and the desire of customers to a large-sized rate influence store also increase as a result of such environmental change. the counter where research of a book was upgraded from differentiation pursuit by competition between business condition in business condition in the case of the domestic rate influence store which has put the focus on service strengthening The work shrine which cannot reach here the competition predominance in the domestic market it will be hard coming to secure, when environmental change of inside large-sized rate influence store industry is taken into consideration The research which tried to receive customer service failure recovery carried out actual proof analysis in the influence to which fair nature lateness of a customer attains to the re-purchase intention to this store of customer satisfaction and future by service recovery process for an object in the customer who held service failure recovery experience in the domestic large-sized rate influence store.

• 품질경영학회지
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• 제21권2호
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• pp.131-139
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• 1993

The newly proposed model of the future reliability results in earlier fault-fixes having a greater effect than the fault which make the greatest contribution to the overall failure rate tend to show themselves earlier, and so are fixed earlier. The suggested model allows a variety of reliability measures to be calculated. Predictions of total execution time(debugging time) is to achieve a target reliability. This model could also apply to computer-hardware reliability growth resulting from the elimination of design error and fault.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 춘계학술대회 논문집 전기설비전문위원
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• pp.16-18
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• 2005

Becoming more and more diversified and complicated, power quality management has focused on the electricity-failure duration(including the numbers), the appropriate rate of voltage(average voltage during 30 minutes), the stability rate of frequency etc. as a basic goal value. And recently the focus is moving into the instantaneous minute interruption factors such as voltage & current harmonics, surge occurring frequency, instantaneous voltage variation, voltage unbalance, instantaneous electricity failure, flicker etc. by the development of electricity & electronics and communication equipments, which had not been so big problems before. This paper will address the flow of analysis technology and forecast the desirable direction of power quality analysis technology in the future.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.593-598
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• 2008

In the present study, degradation characteristics of pumps in nuclear power plants were investigated to provide the information of degradation mechanism and stressors. The failure records of pumps for the periods 2000 to 2006 on INPO(Institute of Nuclear Power Operations) EPIX(Equipment Performance and Information Exchange System) DB were reviewed. The 1,834 failure records reveal that the critical areas of pump failures are bearing, mechanical seal, gasket/o-ring, shaft, impeller, coupling and packing. Based on the failure rate of critical areas, the important degradation mechanism and stressors were determined. Additionally, the relationship between degradation mechanism and stressors such as wear was examined. Finally, the monitoring parameters related to degradation and stressors were discussed for the future development of degradation evaluation and prognosis technology of pumps.