• Journal of the Korean Data and Information Science Society
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• v.7 no.1
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• pp.47-57
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• 1996

This paper on planning constant accelerated life test is assumed that parameters for a lognormal life distribution are depended on changes of stresses. The proposed test plans are optimum in that they minimize the asymptotic variance of maximum likelihood estimator of a specified quantile at the design stress. The optimal amount of low stress level ${\xi}_{L}$ and optimal sample proportion ${\pi}$ to be allocated at low stress level are obtained when the ratio of scales at high stress level and design stress level is unknown.

• Journal of Korean Society for Quality Management
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• v.52 no.1
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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

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.3
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• pp.267-274
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• 2015

It is necessary to both analyze root-cause of non-conformance of effective illumination time to the specification, and estimate the storage lifetime for 81 mm illuminating projectile stockpiled over 10 years. In this paper, aging mechanism of magnesium flare material due to long-term storage was supposed, and two-stage tests, pre-test and main test based on accelerated degradation tests were performed. Field storage environment of moistureproof was set up, and illumination times in the accelerated degradation tests for temperatures 60 and $70^{\circ}C$ were measured. Then, storage reliability of the projectile was estimated through analyzing the measured data and applying distribution-based degradation models to the data. The $B_{10}$ life by which 10 % of a population of the projectiles will have failed at storage temperature of $25^{\circ}C$ was estimated about 7 years.

• Journal of the Korean Data and Information Science Society
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• v.8 no.1
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• pp.21-30
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• 1997

In accelerated life tests, the failure time of an item is observed under a high stress level, and based on the time the performances of items are investigated at the normal stress level. In this paper, when the mean of the prior of a failure rate is known in the exponential lifetime distribution with censored accelerated failure time data, we utilize the empirical Bayesian method by using the moment estimators in order to estimate the parameters of the prior distribution and obtain the empirical Bayesian predictive density and predictive intervals for a future observation under the normal stress level.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.456-458
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• 2022

Due to the environmental regulations of the International Maritime Organization, shipyards are conducting various researches to improve the efficiency of ships, and efforts are being made to reduce the weight of ships. Recently, composite materials including CNT materials have the advantage of being able to reduce weight by 40% or more compared to general steel plate materials, and have the advantage of being able to be used as a substitute for ship clamps or door skins. Therefore, in this study, to predict the life of composite materials including CNT materials, the results were compared through the accelerated deterioration test method and the life prediction using machine learning techniques. The accelerated degradation test used the Arrhenius model equation, and the machine learning method predicted the life using a regression analysis algorithm.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.677-677
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• 1995

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.260-260
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• 1996

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.261-261
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• 1996

• Journal of Korean Society for Quality Management
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• v.23 no.4
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• pp.13-27
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• 1995

This paper considers the design of life test sampling plans based on Type II censored accelerated life tests. The lifetime distribution of products is assumed to be exponential. An estimator of acceleration factor between use condition stress and an accelerated level of stress higher than use condition stress is assumed to be known. The critical value for lot acceptance and the number of failure before censoring which satisfy the producer's and consumer's risk requirements are determined. The properties of the proposed life test sampling plans are investigated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.4
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• pp.388-395
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• 2009

An accelerated fatigue test is essentially required to maintain the reliability of the actual structures of KTX under operation conditions. However, actual fatigue life cannot be obtained because the conventional fatigue tests are not adequate to the real load conditions. Moreover foreign component makers have not provided data of the loading stresses (S) versus cycles at the failure (N). In this study, we suggested a deduction method of the S-N curve for establishing an accelerating test under various load levels. Load history was acquired from the field tests. A Rainflow method was used on the cycle counting of the field load data. After that, an S-N curve was obtained through the iteration process under the condition that the damage index satisfies to 1 in the Miner's rule. The deduced S-N curve was applied to the performance evaluation of Korean-made sealed knuckles compared with imports.