• Korean Journal of Mathematics
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• 제20권3호
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• pp.323-331
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• 2012

We present a high-order potential ow model for the motion of the impulsively accelerated unstable interface of infinite density jump. The Layzer model for the evolution of the interface is extended to high-order. The time-evolution solutions of the bubble and the spike in the interface are obtained from the high-order model. We show that the high-order model gives improvement on the prediction of the evolution of the bubble and the spike.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.445-450
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• 2003

This study was performed 10 develop the accelerated life test method using Weibull-IPL(Inverse Power Law) model for mechanical components. Weibull-IPL model is concerned with determining the assurance life with confidence level and the accelerated life test time From the relation of weibull distribution factors and confidence limit, the testing times on the no number of failure acceptance criteria arc determined. The mechanical components generally represent wear and fatigue characteristics as a failure mode. IPL based on the cumulative damage theory is applied effectively the mechanical components to reduce the testing time and to achieve the accelerating test conditions. As the actual application example, accelerated life test method of agricultural tractor transmission was described. Life distribution of agricultural tractor transmission was supposed to follow Weibull distribution and life test time was calculated under the conditions of average life (MTBF) 3,000 hours and 90% confidence level for one test sample. According to IPL, because test time call be shorten in case increase test load test time could be reduced by 482 hours when we put the load 1.1 times of rated load than 0.73 times of rated load that is equivalent load calculated by load spectrum of the agricultural tractor. This time, acceleration coefficient was 11.7.

• 한국신뢰성학회지:신뢰성응용연구
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• 제15권3호
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• pp.154-162
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• 2015

We have performed accelerated photo-degradation test using a 10-Sun level high irradiance $Weather-Ometer^{(R)}$ (10-Sun Ci5000) in an attempt to study acceleration and correlation between accelerated and service conditions for ink-jet ink. The accelerated test was used to predict lifetimes of ink-jet ink through the calculation of scaling factor for intensity of irradiance and duration of usage combined with estimation of lifetime distribution and inverse power model as a life-stress model. The lifetimes and acceleration factors for foreign and domestic inks were compared with each other. The results showed that the failure mechanisms and life-stress models for ink-jet ink were different among the color of ink which means that we might be in need of further study by color of inks.

• 한국신뢰성학회지:신뢰성응용연구
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• 제12권3호
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• pp.187-199
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• 2012

In general, accelerated life testing is performed to reduce testing time. But it is difficult to apply accelerated life testing to a system besides components. This paper developed a software which estimates reliability measures of the system from results of accelerated life testing of components building the system. This software can handle the system with a large number of components and complex topology. Multiple failure modes of a component were also considered in this software. Based on the software, reliability measures of a gearbox example at several conditions were estimated from the accelerated life testing results of three components of the gearbox.

• 품질경영학회지
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• 제52권1호
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• pp.135-148
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• 2024

Purpose: This study is to investigate the literature on accelerated tests based on the acceleration model and to provide a compilation of results on the parameters applied in the acceleration model and the test conditions. Methods: This research is conducts a literature review on accelerated tests using the acceleration model, with a focus on test targets, test conditions, and parameter values. The study is organizing the results of this literature review to facilitate their application in the design of reliability tests. Results: A literature review investigated a variety of test targets, test conditions, and parameter values. Conclusion: The results of the literature research conducted revealed various acceleration model parameter. Such literature research on accelerated tests can establish the foundation for reliability test design and contribute to future product development and quality improvement

• 한국산업정보학회논문지
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• 제9권2호
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• pp.1-8
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• 2004

본 논문은 누적노출모형에서 수명시간이 지수분포를 따르고 서로 독립일 때 쿨백-라이블러 정보함수를 이용하여 단계 스트레스 가속수명시험으로부터 얻은 자료로부터 모수의 추정량을 제안하고, 단계 스트레스 가속수명시험의 정상조건에서 편의와 평균제곱오차 관점에서 모의실험을 통하여 Vasicek (1976), Van Es (1992)와 Correa (1995)가 제안한 세가지 추정량들에 대한 소표본 특성을 비교 논의하고자 한다.

• Journal of the Korean Data and Information Science Society
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• 제21권4호
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• pp.765-775
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• 2010

For the accelerated failure time (AFT) model a lot of effort has been devoted to develop effective estimation methods. AFT model assumes a linear relationship between the logarithm of event time and covariates. In this paper we propose a semiparametric support vector machine to consider situations where the functional form of the effect of one or more covariates is unknown. The proposed estimating equation can be computed by a quadratic programming and a linear equation. We study the effect of several covariates on a censored response variable with an unknown probability distribution. We also provide a generalized approximate cross-validation method for choosing the hyper-parameters which affect the performance of the proposed approach. The proposed method is evaluated through simulations using the artificial example.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.279-280
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• 2008

Accelerated aging tests were conducted under laboratory conditions on two generator stator bars. Electrical stress is applied in No. 1 model stator bar. Electrical and thermal stresses are applied in No. 2 model stator bar. As aging times increased from 0 to 4780h, diagnostic tests were performed on No. 1 and No. 2 model stator bars. Diagnostic tests included AC current, dissipation factor(tan$\delta$) and partial discharge magnitude. The ${\Delta}tan{\delta}$ and $\Deta$I of No. 1 and No. 2 model stator bars increased with increased in aging time.

• Smart Structures and Systems
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• 제29권6호
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• pp.799-805
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• 2022

Permanent magnet synchronous motors (PMSMs) are widely used in systems requiring high control precision, efficiency, and reliability. Predicting the remaining useful life (RUL) with health monitoring of PMSMs prevents catastrophic failure and ensures reliable operation of system. In this study, a model-based method for predicting the RUL of PMSMs using phase current and vibration signals is proposed. The proposed method includes feature selection and RUL prediction based on a particle filter with a degradation model. The Paris-Erdogan model describing micro fatigue crack propagation is used as the degradation model. An experimental set-up to conduct accelerated life test, capable of monitoring various signals was designed in this study. Phase current and vibration data obtained from an accelerated life test of the PMSMs were used to verify the proposed approach. Features extracted from the data were clustered based on monotonicity and correlation clustering, respectively. The results identify the effectiveness of using the current data in predicting the RUL of PMSMs.

• Journal of the Korean Data and Information Science Society
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• 제7권1호
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• pp.21-35
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• 1996

In this paper, estimation and prediction procedures are discussed for grneral situation in which the failure time follows the independent density $f_{i}({\varepsilon}_{i})$ for the accelerated life testing under Type II censoring. In the context of accelerated life test experiment, procedures are given for estimating the parameters in the Eyring model, and for estimating mean life at a given future stress level. The procedures given are conditional confidence interval procedures, obtained by conditioning on ancillary statistics. A comparison is made of these procedures and procedures based on asymptotic properties of the maximum, likelihood estimates.