• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 춘계학술대회 논문집
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• pp.149-152
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• 2009

In this paper, We has been studied the lifetime degradation of LED lighting system compared to MH lighting. Especially the effect of temperature level on the lifetime degradation has been investigated. The results show that temperature plays a role in the lifetime degradation and slope of degradation line represent as temperature level differently. However, It is possible to estimate the lifetime of LED lighting system using equation induced the slope of degradation line.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.423-424
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• 2016

Recently, the mass production of Energy storage system (ESS) is actively perform around world. Energy storage system is a technique that stores power to energy storage device to supply energy into grid and load at peak-load. Therefore, the efficient energy management is available by using ESS system. The life of Lithium-ion battery is varied corresponding to the power usage, especially selected depth of discharge (DOD). The lifetime of battery is the one of the most issue of the ESS system because of its stability and reliability. Therefore, lifetime management of battery and power converter of ESS module is required. In this paper, the battery lifetime management method estimating residual power and lifetime of lithium ion battery of ESS system is proposed. Also, total avenue prediction of ESS system is simulated considering the total lifetime of battery.

• 한국신뢰성학회지:신뢰성응용연구
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• 제17권4호
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• pp.332-342
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• 2017

Purpose: In this study, the lifetime distribution of a k-out-of-n system with heterogeneous components is suggested as Markov model, and the time-to-failure (TTF) distribution of each component is considered as phase-type distribution (PHD). Furthermore, based on the model, a redundancy allocation problem with a mix of components (RAPMC) is proposed. Methods: The lifetime distribution model for the system is formulated by the structured Markov chain. From the model, the various information on the system lifetime can be ascertained by the matrix-analytic (or-geometric) method. Conclusion: By the generalization of TTF distribution (PHD) and the consideration of heterogeneous components, the lifetime distribution model can delineate many real systems and be exploited for developing system operation policies such as preventive maintenance, warranty. Moreover, the effectiveness of the proposed RAPMC is verified by numerical experiments. That is, under the equivalent design conditions, it presented a system with higher reliability than RAP without component mixing (RAPCM).

• Journal of Multimedia Information System
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• 제1권2호
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• pp.101-110
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• 2014

The purpose of this research is to extend Ad-hoc network system lifetime with the proposed routing protocol which has considered hop lifetimes of the nodes while guaranteeing QoS in the establishment process of Ad-hoc network communication paths. Based on another power aware routing system that proposed in the advanced research [1], we are proposing an alternative power aware routing system in which nodes' hop lifetimes are compared in order to extend the lifetime of an Ad-hoc network system and delay factors have been considered for the assurance of QoS. The research of the routing protocol in this paper, which aims to maximize the system survival time considering power consumption status during the path searching in MANET and pursues the mechanism that controls hop delays for the same reason, can be applied to the study of WSN. The study concerning such phenomena is essential so that the proposed protocol has been simulated and verified with NS-2 in Linux system focusing on the lifetimes of the hops of the nodes. Commercialization of smart devices and arrival of the ubiquitous age has brought about the world where all the people and things are connected with networks. Since the proposed power aware method and the hop delay control mechanism used to find the adequate communication paths in MANET which mainly uses batteries or in WSN, they can largely contribute to the lifetime extension of the network system by reducing power consumptions when utilized for the communications attempts among soldiers during military operation, disaster areas, temporary events or exhibitions, mobile phone shadow areas, home networks, in-between vehicle communications and sense networks, etc. This paper presents the definitions and some advantages regarding the proposed outing protocol that sustain and extend the lifetime of the networks.

• 한국철도학회논문집
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• 제18권2호
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• pp.111-116
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• 2015

LED 조명은 고효율과 장시간의 수명 특성으로 각광받고 있지만 LED소자의 구동전류와 열에 의한 특성으로 예측된 수명에 미치지 못하는 경우가 많다. 특히 철도차량의 전조등의 운행환경은 주변온도 변화에 민감한 구조를 지니고 있다. LED소자에 대한 수명을 예측하기 위한 시험방법 및 예측방법이 북미조명학회에서 LM-80과 TM-21 등으로 제시되고 있지만 수명 확인을 위해 장기간이 소요되며 전류와 온도 등의 다양한 스트레스로 인하여 LED제품에 대한 수명시험 표준이 구체적으로 정립되어 있지 않다. 본 논문에서는 실제품의 수명을 예측할 수 있는 방안과 시험방법의 적합성을 확인하여 궁극적으로 LED제품에 대한 수명시험 표준으로 타당성을 검증하기 위한 선행연구로서 철도차량의 운행환경을 반영한 조건에서 수명 시험이 가능한 측정 설비의 개념 설계안을 제시하고 이에 대한 설계 타당성을 검토한다.

• Journal of Power Electronics
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• 제16권2호
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• pp.778-785
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• 2016

An excess carrier lifetime extraction method is derived for physics-based insulated gate bipolar transistor (IGBT) models with consideration of the latest development in IGBT modeling. On the basis of the 2D mixed-mode Sentaurus simulation, the clamp turn-off test is simulated to obtain the tail current. The proposed excess carrier lifetime extraction method is then performed using the simulated data. The comparison between the extracted results and actual lifetime directly obtained from the numerical device model precisely demonstrates the accuracy of the proposed method.

• 한국안전학회지
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• 제18권1호
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• pp.116-122
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• 2003

몬테칼로법은 복잡한 특히 비선형문제를 푸는데 강력한 공학도구중의 하나이다. 이 방법은 컴퓨터에서의 통계적인 표본추출방법을 이용하여 각종 공학적인 문제에 근사적인 해를 준다. 교량 하나의 요소나 전체교량의 시간 의존적 파괴확률을 예측하는 방법중의 하나로 생애함수가 있다. 이 논문에서는 교량의 요소나 전체 교량의 파괴확률을 예측하기 위하여, 시스템 신뢰성과 생애함수를 이용하여 포트란 프로그램을 개발하였다. 몬테칼로법은 생애함수의 매개변수를 생성하는데 이용되었다. 적용례로서, 개발된 프로그램은 콘크리트-강 합성 교량에 적용되어, 파괴확률을 예측하는데 이용되었다.

• 기술사
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• 제43권2호
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• pp.60-63
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• 2010

This analysis introduces a lube oil circulation system for a big reducer in the chemical process industries. We have been operating the system and found out that the system greatly helped us save the maintenance cost by increasing the lifetime of the reducer.

• 한국신뢰성학회지:신뢰성응용연구
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• 제10권4호
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• pp.279-297
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• 2010

AQS(Air Quality Control System) is the important part of a car air conditioning system. This device intercepts automatically the influx of harmful waste gas. In this paper reliability assessment criteria for AQS are established in terms of quality certification test and lifetime test. The former quality certification test comprises general performance test and environmental test. Items which pass the test undergo lifetime test which guarantees the extent of mean lifetime with certain confidence.

• 한국강구조학회 논문집
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• 제13권5호
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• pp.467-476
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• 2001

고속도로 건설은 미국을 포함한 여러 국가에서 거의 완료되었으며 정부나 고속도로 관계기관은 유지관리쪽에 초점을 맞추고 있다. 교량을 효과적으로 유지관리 하기 위해 교량의 실제 내하력과 잔존수명을 예측하는 것은 매우 시급하다. 이러한 목적으로서 시간에 대한 시스템 신뢰성 해석이 필요하다. 이 논문에서는 Lifetime 분포(함수)를 이용해서 교량의 잔존수명을 예측하기 위한 전형적인 교량의 모델링기법을 개발하였다. Lifetime의 함수변수를 생성하기 위해서 몬테칼로법을 이용하였다. 결과는 지금 존재하는 교량에 대해 최적의 유지관리 계획에 이용될 수 있다.