• Title, Summary, Keyword: Accelerated Model

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Comparison of Proportional Hazards and Accelerated Failure Time Models in the Accelerated Life Tests

  • Jung, H.S.
    • International Journal of Reliability and Applications
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    • v.10 no.2
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    • pp.101-107
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    • 2009
  • In the accelerated tests, the importance of correct failure analysis must be strongly emphasized. Understanding the failure mechanisms is requisite for designing and conducting successful accelerated life test. Under this presumption, a rational method must be identified to relate the results of accelerated tests quantitatively to the reliability or failure rates in use conditions, using a scientific acceleration transform. Most widely used models for relating the results of accelerated tests quantitatively to the reliability or failure rates in use conditions are an accelerated failure time model and a proportional hazards model. The purpose of this research is to compare the usability of the accelerated failure time model and proportional hazards model in the accelerated life tests.

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Semiparametric accelerated failure time model for the analysis of right censored data

  • Jin, Zhezhen
    • Communications for Statistical Applications and Methods
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    • v.23 no.6
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    • pp.467-478
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    • 2016
  • The accelerated failure time model or accelerated life model relates the logarithm of the failure time linearly to the covariates. The parameters in the model provides a direct interpretation. In this paper, we review some newly developed practically useful estimation and inference methods for the model in the analysis of right censored data.

A Review on the Accelerated Life Test Plan: 2006~2015 (2006년 이후 발표된 가속수명시험 계획에 관한 문헌 연구)

  • Sung, Si-Il
    • Journal of Applied Reliability
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    • v.15 no.2
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    • pp.84-89
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    • 2015
  • Accelerated life tests are widely used to evaluate the product reliability within a resonable amount of time and cost. This article provides literature review about accelerated life test plans between 2006~2015. The literature on planning accelerated life tests are reviewed with respect to the test scenario, assumed accelerated model and estimation method and optimization criteria. Finally, recommendations for the future research are presented.

Planning of Accelerated Degradation Tests: In the Case Where the Performance Degradation Characteristic Follows the Lognormal Distribution (성능특성치의 열화가 대수정규분포를 따를 때의 가속열화시험 모형 개발)

  • Lim, Heonsang;Sung, Si-Il
    • Journal of Applied Reliability
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    • v.18 no.1
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    • pp.80-86
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    • 2018
  • Purpose: This article provides a mathematical model for the accelerated degradation test when the performance degradation characteristic follows the lognormal distribution. Method: For developing test plans, the total number of test units and the test time are determined based on the minimization of the asymptotic variance of the q-th quantile of the lifetime distribution at the use condition. Results: The mathematical model for the accelerated degradation test is provided. Conclusion: Accelerated degradation test method is widely used to evaluate the product lifetime within a resonable amount of cost and time. In this article. a mathematical model for the accelerated degradation test method is newly developed for this purposes.

COMPUTATION AND ANALYSIS OF MATHEMATICAL MODEL FOR MOVING FREE BOUNDARY FLOWS

  • Sohn, Sung-Ik
    • Journal of the Korean Mathematical Society
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    • v.37 no.5
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    • pp.779-791
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    • 2000
  • The nonlinear stage of the evolution of free boundary between a light fluid and a heavy fluid driven by an external force is studied by a potential flow model with a source singlarity. The potential flow model is applied to a bubble and spije evolution for constantly accelerated interface (Rayleigh-Taylor instability) and impulsively accelerated interface (Richtmyer-Meshkow instability). The numerical results of the model show that, in constantly accelerated intergace, bubble grows with constant velocity and the spike falls with gravitational acceleration at later times, while the velocity of the bubble in impulsively accelerated interface decay to zero asymp flow model for the bubble and spike for constantly accelerated interface and impulsively accelerated interface.

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A Study on Validation of Accelerated Model for Pneumatic Cylinder (공기압 실린더 가속모형의 유효성 평가에 관한 연구)

  • Kang, Bo-Sik;Kim, Hyoung-Eui;Chang, Mu-Seong;Song, Chang-Seop
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.10
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    • pp.1139-1143
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    • 2009
  • Pneumatic cylinder is widely used as key component of various industry fields just like automation production line. Recently, people begin to pay attention to reduce development period and cost of pneumatic cylinder so research requirements of accelerated life test of pneumatic cylinder have been increased more than ever. In this research, we shall evaluate availability of acceleration model by statistical analysis of acceleration model's predicted value and life data which acquired in a real operation condition after finish accelerated life test of pneumatic cylinder. Also to predict the life of pneumatic cylinder in the operation condition we shall develop new acceleration model equations.

Weibull Step-Stress Type-I Model Predict the Lifetime of Device (소자의 수명 예측을 위한 Weibull Step-Stress Type-I Model)

  • 정재성;오영환
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.6
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    • pp.67-74
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    • 1995
  • This paper proposes the step-stress type-I censoring model for analyzing the data of accelerated life test and reducing the time of accelerated life test. In order to obtain the data of accelerated life test, the step-stress accelerated life test was run with voltage stress to CMOS Hex Buffer. The Weibull distribution, the Inverse-power-law model and Maximum likelihood method were used. The iterative procedure using modified-quasi-linearization method is applied to solve the nonlinear equation. The proposed Weibull step-stress type-I censoring model exactly estimases the life time of units, while reducting the time of accelerated life test and the equipments of test.

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Accelerated Lifetime Data Analysis Using Quantile Regression (분위수 회귀를 이용한 가속수명시험 자료 분석)

  • Roh, Chee-Youn;Kim, Hee-Jeong;Na, Myung-Hwan
    • The Korean Journal of Applied Statistics
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    • v.21 no.4
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    • pp.631-638
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    • 2008
  • Accelerated Lifetime Test is a method of estimation of lifetime quality characteristics under operation condition with the accelerated lifetime data obtained under accelerated stress. In this paper we propose estimation method with accelerated lifetime data using quantile regression. We apply the method to real data with Arrhenius and Inverse power model.

Modeling and Analysis of Accelerated Degradation Testing Data for a Solid State Drive (SSD) (Solid State Drive(SSD)에 대한 가속열화시험 데이터 모델링 및 분석)

  • Mun, Byeong Min;Choi, Young Jin;Ji, You Min;Lee, Yong Jung;Lee, Keun Woo;Na, Han Joo;Yang, Joong Seob;Bae, Suk Joo
    • Journal of Applied Reliability
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    • v.18 no.1
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    • pp.33-39
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    • 2018
  • Purpose: Accelerated degradation tests can be effective in assessing product reliability when degradation leading to failure can be observed. This article proposes an accelerated degradation test model for highly reliable solid state drives (SSDs). Methods: We suggest a nonlinear mixed-effects (NLME) model to degradation data for SSDs. A Monte Carlo simulation is used to estimate lifetime distribution in accelerated degradation testing data. This simulation is performed by generating random samples from the assumed NLME model. Conclusion: We apply the proposed method to degradation data collected from SSDs. The derived power model is shown to be much better at fitting the degradation data than other existing models. Finally, the Monte Carlo simulation based on the NLME model provides reasonable results in lifetime estimation.

Study on Acceleration Factor Model with Accelerated Stress Interactions (가속 스트레스의 교호작용을 고려한 가속계수 모델에 대한 연구)

  • Kim, Hyoung-Eui;Kang, Bo-Sik;Cho, You-Hee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.7
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    • pp.751-757
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    • 2012
  • An accelerated life test (ALT) is a test method that forces components to fail more quickly than they would under use conditions by applying higher overstresses. When two or more accelerating stresses are involved in an ALT, an interaction effect may occur. In previous studies, mostly ALTs without considering an interaction of accelerated stresses and accelerated life models were proposed. The life data obtained are extrapolated using a life-stress relationship to estimate the life distribution at use conditions. We use the general log-linear relationship to model the dependence of life in the Weibull distribution on stress. Therefore, this study suggests the acceleration factor model between the lives at use conditions and accelerated conditions by using mechanical component life data considering an interaction effect. Further, the accelerated life test method and acceleration factor model proposed in this paper will be the basis for adopting an accelerated life test with accelerated stress interactions.