• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2019년도 춘계학술발표대회
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• pp.92-95
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• 2019

CDN은 여러 서버에 데이터를 분산하여 캐시 한 뒤 빠르게 데이터를 배포하는 네트워크이다. 하지만 CDN은 서버 성능에 영향을 받고 데이터의 Lifetime이 얼마 없는 경우 중앙 서버 혹은 데이터 제작자와의 통신을 통해 데이터를 새로 받아야 한다. 반면에, NDN은 데이터를 라우터별로 캐시하여 트래픽을 분산시키고 딜레이를 줄였다. 하지만, 캐시 된 데이터의 Lifetime에 따라 데이터를 받지 못하는 문제가 있다. 본 논문에선 데이터 요청자가 Lifetime 내에 데이터를 못 받으면 요청자의 네트워크 상황과 Interest 패킷의 주기를 고려하여 캐시 된 데이터의 Lifetime을 증가시켜 안정성 있는 데이터 배포를 목표로 하였다. 캐시 정책이 적용된 시뮬레이션을 진행했으며, 얼마 남지 않은 Lifetime을 증가시켜 데이터 요청자가 데이터를 온전히 받을 수 있음을 확인하였다.

• 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.

• 한국신뢰성학회지:신뢰성응용연구
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• 제4권2호
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• pp.73-90
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• 2004

We performed the heat aging test to predict the useful lifetime of Elastomeric Bearing Chloroprene Rubber (CR) used for supporting bridge. During the test, we measured elongation that are influenced by temperature and aging time. The failure of a test piece is defined as the point at which the elongation reaches to 75% of the initial value. This failure criterion is based on KS F 4420: 1998 (Elastomeric Bearing for bridge). Through the accelerated heat aging test, we found that the Arrhenius relationship and the Weibull lifetime distribution are appropriate as the life-temperature relationship and lifetime distribution of the CR, respectively. Using the Arrhenius -Weibull model, the parameters of the model are estimated and the lifetime of the CR at use condition is predicted.

• 한국신뢰성학회지:신뢰성응용연구
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• 제14권4호
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• pp.220-224
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• 2014

A Bayesian zero-failure reliability demonstration test method for products with Weibull lifetime distribution is presented. Inverted gamma prior distribution for the scale parameter of the Weibull distribution is used to design the Bayesian test plan and selecting a prior distribution using a prior test information is discussed. A test procedure with zero-failure acceptance criterion is developed that guarantee specified reliability of a product with given confidence level. An example is provided to illustrate the use of the developed Bayesian reliability demonstration test method.

• 전기학회논문지
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• 제58권2호
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• pp.308-313
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• 2009

This paper presents a reliability analysis of S-bonds for AF track circuits, which detect train movement and transmit a speed control signal to the train. Field survey shows that S-bonds are exposed to very large vibrations transferred from rail, and suffer from frequent failures when they were installed on ballasted track. We collected the time-to-failure data of S-bonds from the maintenance field of Seoul metro line 2, and made a parametric approach to estimate the statistical distribution that fits the time-to-failure data. The analysis shows that S-bonds have time-to-failure characteristics described by Weibull distribution. The estimated shape parameter of Weibull distribution is 1.1, which means the distribution has constant failure rate characteristics like exponential distribution. The reliability function, hazard function, percentiles and mean lifetime are derived for maintenance support.

• Journal of the Korean Data and Information Science Society
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• 제14권4호
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• pp.1055-1065
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• 2003

We shall propose maximum likelihood, Bayesian and generalized maximum likelihood estimation for the reliability of the two-unit hot standby system with exponential lifetime distribution that switch is perfect. Each estimation will be compared numerically in terms of various mission times, parameter values and asymptotic relative efficiency through Monte Carlo simulation.

• 한국신뢰성학회지:신뢰성응용연구
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• 제1권2호
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• pp.139-148
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• 2001

We are concerned in the estimation of lifetime distribution of a component having a few observed failure data and we demonstrate that we can use the maximum likelihood estimation utilizing the censored data when the number of components in use is quite large. Weibull distribution is assumed for the lifetime and a simple estimation procedure is introduced. We also propose the method of determining the optimal number of spares required for a specified period without introducing cost functions. The proposed methods are applied to the photon stop and the water-cooled flange which are major components in Pohang Light Source.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2000년도 춘계학술대회 발표논문집
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• pp.201-208
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• 2000

We are concerned in the estimation of lifetime distribution of a component having a few observed failure data and we demonstrate that we can use the maximum likelihood estimation utilizing the censored data when the number of components in use is quite large. Weibull distribution is assumed fur the lifetime and a simple estimation procedure is introduced. We also propose the method of determining the optimal number of spares required for a specified period without introducing cost functions. The proposed methods are applied to the photon stop and the water-cooled flange which are major components in Pohang Light Source.

• Journal of the Korean Data and Information Science Society
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• 제15권1호
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• pp.239-250
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• 2004

We shall propose maximum likelihood, Bayesian and generalized maximum likelihood estimation for the reliability of the two-unit hot standby system with Rayleigh lifetime distribution that switch is perfect. Each estimation will be compared numerically in terms of various mission times, parameter values and asymptotic relative efficiency through Monte Carlo simulation.

• Communications for Statistical Applications and Methods
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• 제24권3호
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• pp.227-240
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• 2017

In this paper, we introduce the inverted exponentiated Weibull (IEW) distribution which contains exponentiated inverted Weibull distribution, inverse Weibull (IW) distribution, and inverted exponentiated distribution as submodels. The proposed distribution is obtained by the inverse form of the exponentiated Weibull distribution. In particular, we explain that the proposed distribution can be interpreted by Marshall and Olkin's book (Lifetime Distributions: Structure of Non-parametric, Semiparametric, and Parametric Families, 2007, Springer) idea. We derive the cumulative distribution function and hazard function and calculate expression for its moment. The hazard function of the IEW distribution can be decreasing, increasing or bathtub-shaped. The maximum likelihood estimation (MLE) is obtained. Then we show the existence and uniqueness of MLE. We can also obtain the Bayesian estimation by using the Gibbs sampler with the Metropolis-Hastings algorithm. We also give applications with a simulated data set and two real data set to show the flexibility of the IEW distribution. Finally, conclusions are mentioned.