• Proceedings of the Korean Reliability Society Conference
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• 2005.06a
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• pp.141-145
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• 2005

Nowadays, most industries take $B_{6\sigma}$ quality level as a goal of the ultimate quality level of their products. On the other hand, $B_{10}$ to life indicates the time that $10\%$ of products are failed. There is no relation between the $B_{6\sigma}$ quality level and the $B_{10}$ to life. Therefore, some industries perform their quality control activities and reliability engineering activities separately. So I propose one measure which can express quality and reliability level simultaneously for the products to pursue quality and reliability activities together in the industry.

• Journal of Applied Reliability
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• v.11 no.1
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• pp.1-15
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• 2011

Automobile markets are so fierce in the world market that every major manufacturer assure the buyer of the car by give a provocative warranty plan for their cars. For instance Hyundai motor company offer 10 years and 100,000 miles of warranty whichever comes first. But in order for this effort to be successful every critical component such as window switch has to be proven to be reliable in an adverse environment. Therefore, in this article reliability assessment criteria for window switch are established in terms of basic performance test, environment test and life test.

• Journal of applied mathematics & informatics
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• v.19 no.1_2
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• pp.439-445
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• 2005

This paper is to investigate the approximate confidence limits of the reliability performances (such as failure rate, reliability function and average life) for a cold standby series system. The Bayesian approximate upper confidence limit of failure rate is obtained firstly, and next Bayesian approximate lower confidence limits for reliability function and average life are presented. The expressions for calculating Bayesian lower confidence limits of the reliability function and average life are also obtained, and an illustrative example is examined numerically by means of the Monte-Carlo simulation. Finally, the accuracy of confidence limits is discussed.

• International Journal of Reliability and Applications
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• v.14 no.1
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• pp.27-39
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• 2013

In this article, a new model based on the Rayleigh distribution is introduced. This model is useful and practical in physics, reliability, and life testing. The statistical and reliability properties of this model are presented, including moments, the hazard rate, the reversed hazard rate, and mean residual life functions, among others. In addition, it is shown that the distributions of the new model are ordered regarding the strongest likelihood ratio ordering. Four estimating methods, namely, method of moment, maximum likelihood method, Bayes estimation, and uniformly minimum variance unbiased, are used to estimate the parameters of this model. Simulation is used to calculate the estimates and to study their properties. Finally, the appropriateness of this model for real data sets is shown by using the chi-square goodness of fit test and the Kolmogorov-Smirnov statistic.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.12
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• pp.1048-1058
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• 2017

One of the failure mechanism of spaceborne electronics is a fatigue fracture on solder joint under launch random vibration. Thus, a necessity of early diagnosis through the fatigue life evaluation on solder joint arises to prevent such potential risk of failure. The conventional life prediction methods cannot assure the accuracy of life estimation results if the packaging type changes, and also requires much time and effort to construct the analysis model of highly integrated PCB with various packaging types. In this study, we performed life prediction of PCB based on a reliability and life prediction tool of sherlock as a new approach for evaluating the structural reliability on solder joint, and those prediction results were validated by fatigue tests. In addition, we also investigated an influence of solder height on the fatigue life of solder joint. These results indicated that the Sherlock is applicable tool for evaluating the structural reliability of spaceborne electronic.

• Journal of Korean Academy of Nursing
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• v.47 no.1
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• pp.86-97
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• 2017

Purpose: The purpose of this study was to develop and test the psychometric properties of the newly developed instrument, Meaning in Life, for elderly Korean people. Methods: Ten older adults participated in the qualitative research used to develop the initial items. Participants for the psychometric testing were 371 community-dwelling older adults. Validity and reliability analyses included content, construct, and criterion-related validities, internal consistency, and test-retest reliability. Results: The Meaning in Life Scale consisted of 12 items with three distinct factors; value of life, source of life, and will to live, which explained 86.7% of the total variance. A three-factor structure was validated by confirmatory factor analysis. Criterion-related validity was supported by comparison with the Purpose in Life Test (r=.74). Reliabilities were secured with test-retest reliability of Intra-class Correlation Coefficient (ICC) .85 and the Cronbach's alpha coefficient .90. Conclusion: The results of this study indicate that this instrument is useful to measure meaning in life in Korean elders.

• Journal of Korean Society for Quality Management
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• v.25 no.4
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• pp.206-212
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• 1997

This paper considers the problem of estimating parameters and reliability of shared parallel system with two identical components using type II censored system life data. Likelihood functions are derived and maximum likelihood estimates of parameters and reliability are discussed numerically.

• Proceedings of the Safety Management and Science Conference
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• 2007.04a
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• pp.309-322
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• 2007

This paper shows application guide of dependability data from the field, life cycle costing, and maintainability. Moreover, this study introduces mathematical expressions and predictions for reliability, availability and maintainability. This paper also shows compliance test procedures for steady-state availability, and application of Markov techniques.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.320-323
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• 2005

This paper discusses heat problem of IC, which composes the electronic instruments, to guarantee reliability of electronic instruments. And also proposes the unified equivalent model for various electronic instrument products to guarantee reliability and life of its parts. Because electronic instruments are down sizing and operated with high frequency, the internal temperature of electronic instruments is rising steadily. The internal temperature of the electronic instruments gives a big effect to electronic instrument's reliability and life. The semiconductor parts are the representative heat generation parts because of its complicated function, high frequency and high density. Consequently, guaranteeing reliability and life of electronic semiconductor is the important start point in securing the reliability and life of the electronic instrument product. Unfortunately, there are many factors, which affect heat dissipation efficiency. The heat dissipation efficiency follows the environment where the electronic instrument products are used. Therefore it is very difficult to define reliability and life of the electronic manufactures. Electronic instrument products are composed of printed circuit board (PCB), integrated circuit (IC), resistance, and capacitor and so on. And there are superposed thermal resistances, because the parts are arrayed on the printed circuit board (PCB), Therefore the total thermal resistance is variable. Consequently it cannot have same thermal model for each electronic instrument products. In the next part, we propose the unified equivalent model for various electronic instruments. And using the proposed equivalent model proofs the method for analysis reliability of electronic parts.

• International Journal of Reliability and Applications
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• v.3 no.2
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• pp.91-98
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• 2002

A class of life distributions, whose mean residual life keeps stable at its earlier phase and then starts to decrease in time, is proposed to model the life of an element haying survived its burn-in. A strongly consistent estimator and a nonparametric testing procedure are developed to locate the occurrence of the change-point of the mean residual life. Finally, some numerical simulations are employed to be an illustration as well.