• Journal of Applied Reliability
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• v.15 no.3
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• pp.139-144
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• 2015

Track drive unit adopted in the small sized excavator generally have been used in the construction equipment under the 10 tons as the driving device with forwarding and reversing of excavator. It is required to study the accelerated life test applied by over torque and speed to test the durability life test reflected the many driving modes of small sized excavator and also need to equip the comprehensive performance and life test equipments to do the various performance tests. This study had analyzed the failure modes of the components, and calculated the equivalent loads investigated the used loads in the real field conditions and elicits the acceleration factor adopted in the inverse power model. Also, this study have considered the changes of the acceleration factor and the durability test time in the case of the rotary group and the bearing through analyzing the main failure modes. It was calculated the no failure test time about 2 samples and confidence level 90% and elicited the accelerated life time 720 hours.

• International Journal of Automotive Technology
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• v.3 no.4
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• pp.129-135
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• 2002

Durability estimation of a prototype vehicle has traditionally relied heavily on accelerated durability tests using predefined proving grounds or rig tests using a road simulator. By use of those tests, it is very difficult to predict durability failures in actual service environments. This motivated the development of an integrated CAE (Computer Aided Engineering) methodology for the durability estimation of a prototype vehicle in actual service environments. Since expensive computational costs such as computation time and hardware resources are required for a full vehicle simulation in those environments with a very long span of event time, the conventional CAE methodologies have little feasibility. An efficient computational methodology for durability estimations is applied with theoretical developments. The effectiveness of the proposed methodology is shown by the comparison of results of the typical actual service environment such as the city mode with those of the typical accelerated durability test over the Belgian road.

• Journal of the Korean Statistical Society
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• v.18 no.2
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• pp.125-134
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• 1989

This paper presents optimum simple step-stress accelerated life test plans for the case where the test process is observed periodically at intervals of the same length. Two types of failure data, periodically observed complete data and periodically observed censored data, are considered. An exponential life distribution with a mean that is a log-linear function of stress, and a cumulative exposure model for the effect of changing stress are assumed. For each type of data, the optimum test plan which minimizes the asymptotic variance of the maximum likelihood estimator of the mean life at a design stress is obtained and its behaviors are studied.

• Journal of Applied Reliability
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• v.5 no.2
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• pp.221-239
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• 2005

General chip SMD parts(chip resistance, chip capacitor, chip varistor etc.) are very wide used electronics parts for IT units. But, failure modes are indistinct for these chip parts. In factory and field the failure modes are recognized to accidental failure mode caused by potential defect. In this paper used chip varistor ALT(Accelerate Life Test) test for verify general failure modes in chip SMD parts. Also the results are useful for general chip SMD ALT tests.

• Proceedings of the Korean Reliability Society Conference
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• 2005.06a
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• pp.51-67
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• 2005

General chip SMD parts(chip resistance, chip capacitor, chip varistor etc.) are very wide sed electronics parts for IT units. But, failure modes are indistinct for these chip parts. In factory and field the failure modes are recognized to accidental failure mope caused by potential defect. In this paper used chip varistor ALT(Accelerate Life Test) test for verify general failure modes in chip SMD parts. Also the results are useful for general chip SMD ALT tests.

• Journal of Applied Reliability
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• v.17 no.4
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• pp.343-354
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• 2017

Purpose: This paper evaluates the reliability of tapered grid couplings and presents test results through performance and life tests. Methods: The performance and life test method were presented by analyzing the failure modes for the tapered grid coupling. Zero failure test time was calculated to evaluate the reliability of tapered grid couplings and the test was performed under accelerated conditions. The nondestructive test and wear analysis using weighing were also carried out to check the failure modes of the field conditions. Conclusion: This study can be provided to improve the product reliability through failure analysis of a tapered grid coupling. The performance test results of before and after the accelerated life test were presented to confirm the improved reliability of the tapered grid coupling.

• Journal of Drive and Control
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• v.15 no.4
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• pp.23-29
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• 2018

The objective of this paper is to evaluate the reliability of a volute pump and presents test results through performance and life tests. The performance and life test methods were presented by analyzing the failure modes of the volute pump. Zero failure test time was calculated to evaluate the reliability of the volute pump and then, the test was performed under accelerated conditions. The test was also carried out to check the failure modes of the field conditions. This study can be provided to improve the product reliability through failure analysis of the volute pump. And failure cause of typical failure case has been investigated and improvement design has been presented. The performance test results of before and after the accelerated life test were presented to confirm the improved reliability of the volute pump.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.2
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• pp.241-248
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• 2019

In this paper, we aim to check the reliability growth of multiple launch rocket components by the life evaluation. We apply the Crow-AMSAA model to the sets of test data obtained from the development phase. The result of the data analysis shows that the reliability of some components needs to be improved. In order to improve their reliability, we analyze the failure mechanism and change their designs. The verification of the reliability growth for those components is done by analyzing the data sets obtained by the accelerated life tests. As a result, we show that the MTBF of those components is increased and also their reliabilities improved.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.393-397
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• 2006

The study about Accelerated Life Test and analysis of failed data is increased in order to predict and evaluate reliability of products, according as the development cycle of products is reduced. Therefore, the decision of optimal distribution function about failed data for accurate analysis of failed data and test condition for Accelerated Life Test is very important. This paper compares Anderson-Darling method with Likelihood Function method for the decision of optimal distribution function about failed data. Anderson-Darling considers only failed data and Likelihood Function considers both failed data and life-stress relationship in decision of distribution function. In the results of comparison about two methods, we found that the distribution function chosen by each method is different and the life time predicted by each decided distribution function is different.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.624-630
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• 2006

This paper studies a modeling to demonstrate predicted reliability of the train control system components by performing an accelerated stress test. There are two tests for demonstrating predicted reliability; test run at the whole system level, and accelerated life test and accelerated stress test at the component level. In this paper, we imposed accelerated stress on the system and studied the train control system modeling for the accelerated stress test, which demonstrates predicted reliability according to whether or not the equipment is operating. Reliability of train control system consisting of electronic components varies drastically according to temperature so we considered the Arrhenius equation and the activation energy of electronic components. We also used reliability modeling with weighted average and calculated time necessary to complete the accelerated stress test on train control system.