• Title/Summary/Keyword: Data Reliability

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Reliability Analysis Method for Repeated UT Measurement Data in Nuclear Power Plants (원전 배관의 반복 측정 데이터에 대한 신뢰도 분석 방법)

  • Yun, Hun;Hwang, Kyeong-Mo
    • Corrosion Science and Technology
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    • v.12 no.3
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    • pp.142-148
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    • 2013
  • Safety is a major concern in Nuclear Power Plants (NPPs). Piping systems in NPPs are very complex and composed of many components such as tees, elbows, expanders and straight pipes. The high pressure and high temperature water flows inside piping components. As high speed water flows inside piping, the pipe wall thinning occurs in various reasons such as FAC (Flow Accelerated Corrosion), LDIE (Liquid Droplet Impingement Erosion) and Flashing. To inspect the wall thinning phenomenon and protect the piping from damages, piping components are checked by UT measurement in every overhaul. During every overhaul, approximately 200~300 components (40,000~60,000 UT data) are examined in NPPs. There are some methods from EPRI for evaluating wear rate of components. However, only few studies have been conducted to find out the raw data reliability for the wear rate evaluation. Securing the reliable raw data is the key factor for a reasonable evaluation. This paper suggests the reliability analysis method for the repeatedly measured data for wear rate evaluation.

Influence Analysis of Sampling Points on Accuracy of Storage Reliability Estimation for One-shot Systems (원샷 시스템의 저장 신뢰성 추정 정확성에 대한 샘플링 시점의 영향 분석)

  • Chung, Yong H.;Oh, Bong S.;Lee, Hong C.;Park, Hee N.;Jang, Joong S.;Park, Sang C.
    • Journal of Applied Reliability
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    • v.16 no.1
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    • pp.32-40
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    • 2016
  • Purpose: The purpose of this study is to analyze the effect of sampling points on accuracy of storage reliability estimation for one-shot systems by assuming a weibull distribution as a storage reliability distribution. Also propose method for determining of sampling points for increase the accuracy of reliability estimation. Methods: Weibull distribution was divided into three sections for confirming the possible to estimate the parameters of the weibull distribution only some section's sample. Generate quantal response data for failure data. And performed parameter estimation with quantal response data. Results: If reduce sample point interval of 1 section, increase the accuracy of reliability estimation although sampling only section 1. Even reduce total number of sampling point, reducing sampling time interval of the 1 zone improve the accuracy of reliability estimation. Conclusion: Method to increase the accuracy of reliability estimation is increasing number of sampling and the sampling points. But apply this method to One-shot system is difficult because test cost of one-shot system is expensive. So propose method of accuracy of storage reliability estimation of one-shot system by adjustment of the sampling point. And by dividing the section it could reduce the total sampling point.

Reliability Evaluation on Creep Life Prediction of Alloy 617 for a Very High Temperature Reactor (초고온 가스로용 Alloy 617의 크리프 수명예측 신뢰성 평가)

  • Kim, Woo-Gon;Park, Jae-Young;Kim, Seon-Jin;Hong, Sung-Deok;Kim, Yong-Wan
    • Korean Journal of Metals and Materials
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    • v.50 no.10
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    • pp.721-728
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    • 2012
  • This paper evaluates the reliability of creep rupture life under service conditions of Alloy 617, which is considered as one of the candidate materials for use in a very high temperature reactor (VHTR) system. A Z-parameter, which represents the deviation of creep rupture data from the master curve, was used for the reliability analysis of the creep rupture data of Alloy 617. A Service-condition Creep Rupture Interference (SCRI) model, which can consider both the scattering of the creep rupture data and the fluctuations of temperature and stress under any service conditions, was also used for evaluating the reliability of creep rupture life. The statistical analysis showed that the scattering of creep rupture data based on Z-parameter was supported by normal distribution. The values of reliability decreased rapidly with increasing amplitudes of temperature and stress fluctuations. The results established that the reliability decreased with an increasing service time.

Development of Reliability Simulator for Electronic Components (전자부품 통합 신뢰성 Simulator 개발)

  • Kim, Wan-Doo;Lee, Seung-Woo;Han, Seung-Woo;Osterman, Michael
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.1749-1753
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    • 2007
  • The reliability, that is Long-Term Quality, require an approaching different from Short-Term Quality which is used before. As the electronic components are able to be easily normalized on the reliability testing, various testing standards are used. In this study, we proposed two reliability simulator that is PoF(Physics of Failure)-based and failure rate models-based. PoF-based simulator is introduced based on CalceEP program that is created by University of Maryland. This simulator can be modified by user interface of properties and PoF models and operated on stand alone system. Failure rate models-based simulator introduced according to analyzing reliability prediction documents. Also, unified database including failure data models is built from existing MIL-HDBK-217F N2, PRISM, and Bellcore, and web-based simulator is developed. The developed reliability simulator will service of the PoF model, properties, failure rate model accumulated and its data by web and internet.

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Using R Software for Reliability Data Analysis

  • Shaffer, Leslie B.;Young, Timothy M.;Guess, Frank M.;Bensmail, Halima;Leon, Ramon V.
    • International Journal of Reliability and Applications
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    • v.9 no.1
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    • pp.53-70
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    • 2008
  • In this paper, we discuss the plethora of uses for the software package R, and focus specifically on its helpful applications in reliability data analyses. Examples are presented; including the R coding protocol, R code, and plots for various statistical as well as reliability analyses. We explore Kaplan-Meier estimates and maximum likelihood estimation for distributions including the Weibull. Finally, we discuss future applications of R, and usages of quantile regression in reliability.

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Estimations of the Parameters in a Two-component System Using Dependent Masked Data

  • Sarhan Ammar M.
    • International Journal of Reliability and Applications
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    • v.6 no.2
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    • pp.117-133
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    • 2005
  • Estimations of the parameters included in a two-component system are derived based on masked system life test data, when the probability of masking depends upon the exact cause of system failure. Also estimations of reliability for the individual components at a specified mission time are derived. Maximum likelihood and Bayes methods are used to derive these estimators. The problem is explained on a series system consisting of two independent components each of which has a Pareto distributed lifetime. Further we present numerical studies using simulation.

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Estimating the reliability and distribution of ratio in two independent variables with different distributions

  • Yun, Sang-Un;Lee, Chang-Soo
    • Journal of the Korean Data and Information Science Society
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    • v.23 no.5
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    • pp.1017-1025
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    • 2012
  • We consider estimations for the reliability in two independent variables with Pareto and uniform or exponential distributions. And then we compare the mean squared errors of two reliability estimators for each case. We also observe the skewness of densities of the ratio for each case.

A Comparative Study on Nonparametric Reliability Estimation for Koziol-Green Model with Random Censorship

  • Cha, Young-Joon;Lee, Jae-Man
    • Journal of the Korean Data and Information Science Society
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    • v.8 no.2
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    • pp.231-237
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    • 1997
  • The Koziol-Green(KG) model has become an important topic in industrial life testing. In this paper we suggest MLE of the reliability function for the Weibull distribution under the KG model. Futhermore, we compare Kaplan-Meier estimator, Nelson estimator, Cheng & Chang estimator, and Ebrahimi estimator with proposed estimator for the reliability function under the KG model.

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A Study on the Reliability(Environmental) Test Trend in Korea Electronic Industries (국내 전자부품 중소기업의 신뢰성 시험 활용현황 및 지원방향)

  • Kang, Bo-Chul;Cho, Jai-Rip
    • Proceedings of the Korean Society for Quality Management Conference
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    • 2007.04a
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    • pp.331-333
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    • 2007
  • Product reliability is important to quality and competitiveness. Much management and engineering efforts go into evaluating reliability, assessing new designs and changes of manufacturing processes, identifying cause of failure. Major methods are based on environmental test. In this study, we analysis the environmental test data of the electrical component, unit, set. These data were gathered for 7 years.

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Reliability assesment of tilting train using Fault Diagnosis analysis device (고장진단분석장치를 이용한 틸팅열차 신뢰성 평가 연구)

  • Han, Seong-Ho
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.1203_1204
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    • 2009
  • Korean Tilting trains have tested on conventional lines since the beginning of 2007 for evaluating its reliability. We achieved some major performance tests which are the maximum operation speed 180km/h test and the maximum curves increasing speed with tilting operation test. In order to analysis reliability data of tilting train, we have used the special data aquisition system which consists of monitor, sensors and depot computer etc. As a results of calculation, until now we realized that the reliability are getting more increasing than starting point of running test.

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