• Title/Summary/Keyword: Data Reliability

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Reliability Estimation for a Shared-Load System Based on Freund Model

  • Hong, Yeon-Woong;Lee, Jae-Man;Cha, Young-Joon
    • Journal of the Korean Data and Information Science Society
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    • v.6 no.2
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    • pp.1-7
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    • 1995
  • This paper considers the reliability estimation of a two-component shared-load system based on Freund model. Maximum likelihood estimator, order restricted maximum likelihood estimator and uniformly minimum variance unbiased estimator of the reliability function for the system are obtained. Performance of three estimators for moderate sample sizes is studied by simulation.

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On the Estimation of Reliability Functions for the Freund Model

  • Hong, Yeon-Woong;Lee, Jae-Man;Cha, Young-Joon
    • Journal of the Korean Data and Information Science Society
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    • v.8 no.1
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    • pp.79-83
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    • 1997
  • This paper considers the problem of estimating the model parameters and reliability functions for Freund bivariate exponential distribution. Uniformly minimum variance unbiased estimators for model parameters, joint reliability and marginal reliability functions are obtained in the both case of non-identically distributed marginals and identically distributed marginals.

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Inference on the reliability P(Y < X) in the gamma case

  • Moon, Yeung-Gil;Lee, Chang-Soo
    • Journal of the Korean Data and Information Science Society
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    • v.20 no.1
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    • pp.219-223
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    • 2009
  • We shall derive a quotient distribution of two independent gamma variables and its moment and reliability are represented by hypergeometric function and Wittaker's function. And we shall consider an inference on the reliability in two independent gamma random variables.

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The Reliability Estimation of Parallel System in Bivariate Exponential Model : Using Bivariate Type 1 Censored Data (이변량 지수모형에서 병렬시스템의 신뢰도 추정 : 이변량 1종 중단 자료이용)

  • 조장식;김희재
    • Journal of Korean Society for Quality Management
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    • v.25 no.4
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    • pp.79-87
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    • 1997
  • In this paper, we obtain maximum likelihood estimator(MLE) of a parallel system reliability for the Marshall and Olkin's bivariate exponential model with birariate type 1 consored data. The asymptotic normal distribution of the estimator is obtained. Also we construct an a, pp.oximate confidence interval for the reliability based on MLE. We present a numerical study for obtaining MLE and a, pp.oximate confidence interval of the reliability.

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Bayesian Reliability Estimation of Two-Unit Rot Standby System

  • Lee, Chang-Soo;Kim, Hee-Jae;Moon, Yeung-Gil;Lee, Jang-Choon
    • Journal of the Korean Data and Information Science Society
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    • v.9 no.1
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    • pp.89-94
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    • 1998
  • We shall propose several Bayes estimators for reliability of a two-unit hot standby system with the imperfect switch based upon a complete sample of failure times observed from an exponential distribution, and the proposed reliability Bayesian estimators are compared numerically each other in sense of mean squared error.

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Reliability Evaluation of Power Distribution System Considering Maintenance Effects (유지보수 영향을 고려한 배전계통 신뢰도 평가)

  • Moon, Jong-Fil;Shon, Jin-Geun
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.59 no.2
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    • pp.154-157
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    • 2010
  • In this paper, the Time-varying Failure Rates(TFR) of power distribution system components are extracted from the recorded failure data of KEPCO(Korea Electric Power Corporation) and the reliability of power distribution system is evaluated using Mean Failure Rate(MFR) and TFR. The TFR is approximated to bathtub curve using the exponential and Weibull distribution function. In addition, Kaplan-Meier estimation is applied to TFR extraction because of incomplete failure data of KEPCO. Also the reliability of the real power distribution system of Korea is evaluated using the MFR and TFR extracted from real failure data, respectively and the results of each case are compared with each other. As a result, it is proved that the reliability evaluation using the TFR is more realistic than MFR. In addition, it is presented that the application method at power distribution system maintenance and repair using the result of TFR.

Method and Application for Reliability Analysis of Measurement Data in Nuclear Power Plant (원전 배관의 두께 측정 데이터에 대한 신뢰도 분석 방법 및 적용)

  • Yun, Hun;Hwang, Kyeongmo;Lee, Hyoseoung;Moon, Seungjae
    • Corrosion Science and Technology
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    • v.14 no.1
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    • pp.33-39
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    • 2015
  • Pipe wall-thinning by flow-accelerated corrosion and various types of erosion is significant damage in secondary system piping of nuclear power plants(NPPs). All NPPs in Korea have management programs to ensure pipe integrity from degradation mechanisms. Ultrasonic test(UT) is widely used for pipe wall thickness measurement. Numerous UT measurements have been performed during scheduled outages. Wall-thinning rates are determined conservatively according to several evaluation methods developed by Electric Power Research Institute(EPRI). The issue of reliability caused by measurement error should be considered in the process of evaluation. The reliability analysis method was developed for single and multiple measurement data in the previous researches. This paper describes the application results of reliability analysis method to real measurement data during scheduled outage and proved its benefits.

Reliability Analysis of UT Measurement for Evaluating Pipe Wall Thinning in Nuclear Power Plants (배관감육 평가를 위한 UT 측정 신뢰도 분석)

  • Yun, Hun;Hwang, Kyeong-mo
    • Corrosion Science and Technology
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    • v.11 no.4
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    • pp.129-134
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    • 2012
  • UT(Ultrasonic Test), one of the non-destructive tests, is the most common thickness measurement method for evaluating the wear rate in NPPs(Nuclear Power Plants). UT is used widely because it is easy and safe for use. However some amount of error inevitably occurs in attempting to measure the thickness. The error, that could make the thickness data thicker or thinner, may affect estimation of wear rate in pipes. NPPs are composed of a lot of pipes and components. Some of them are tested to check the current status during RFO(Re-Fueling Outage). Reliability analysis of UT is essential for evaluating pipe wear rate and establishing the long-term management plan in NPPs. This paper reviewed the cause of error occurrence and presented the UT data reliability analysis method. Also, this paper shows the application result of reliability analysis to the UT data acquired in NPPs.

Development of LCCA Module Using STEP-based LCCA Data Structure (STEP 기반 LCC 분석 데이터구조를 이용한 LCC 분석모듈 개발)

  • Kim, Dong-Hyun;Huang, Meng-Gang;Kim, Bong-Geun;Lee, Sang-Ho
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2007.04a
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    • pp.803-808
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    • 2007
  • LCCA module enabling to estimate LCC and analyze time-variant reliability index of a plate girder bridge was developed. The developed module was based on the designed data structure following the standardized methodology of ISO/STEP, LCCA module consisted of LCC estimation module, which is composed of six sub modules according to the cost category, and reliability index analysis module, which is composed of time-variant corrosion sub module, time-variant live load sub module, and element reliability analysis sub module, The effectiveness of the developed LCCA module was verified by estimating LCC and analyzing time-variant reliability index of a plate girder bridge on the basis of the constructed test database.

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A Study on Development of Korean Failure Rate Databook (한국형 고장률 데이터 북 개발에 대한 연구)

  • Paik, Soonheum;Lim, Jae-hak
    • Journal of Applied Reliability
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    • v.17 no.4
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    • pp.305-315
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    • 2017
  • Purpose: The purpose of this research is to propose procedure and methodology for developing failure rate databook which is suitable for Korean operation environment. Methods: To this end, we investigate failure databooks used in foreign countries and study the procedure and methodology for collecting failure data, organizing the data, estimating failure rate and summarizing results. Results: We develop the procedure of development of failure databook, the items for data collection, database schema of part details and part summary and contents of failure databook by considering the application environment in Korea. Conclusion: The results of our research could be utilized for the development of Korean failure rate databook and research of reliability prediction model and could ultimately contribute to improve the accuracy of reliability prediction.