• Journal of the Korean Data and Information Science Society
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• v.7 no.1
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• pp.37-46
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• 1996

In this paper, we introduce the goodness of fit test procedure for lifetime distribution using step stress accelerated lifetime data. Using the nonpapametric estimate of acceleration factor, we prove the strong consistence of empirical distribution function under null hypothesis. The critical vailues of Kolmogorov-Smirnov, Anderson-Darling, Cramer-von Mises statistics are computed when the lifetime distibution is assumed to be exponential and Weibull. The power of test statistics are compared through Monte-Cairo simulation study.

• Journal of Applied Reliability
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• v.12 no.3
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• pp.165-176
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• 2012

Hydrostatic bearing improves performance and life time of a product by avoiding solid friction and reducing viscosity friction with the help of creating pressure equilibrium between two faces doing relative motion. This study suggests failure analysis and test evaluation for a ball joint that adopts the hydrostatic bearing and introduces the entire process to improve reliability of the product by design improvement. A typical failure is growth of friction torque by solid friction, and its failure cause is determined and the improvement is proposed. Finally, reliability improvement is established by analysis of the results of before and after acceleration test.

• International Journal of Reliability and Applications
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• v.1 no.2
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• pp.155-165
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• 2000

In this paper, we propose some estimators of Kullback- Leibler Information functions using the data from three step stress accelerated life tests. This acceleration model is assumed to be a tampered random variable model. Some asymptotic properties of proposed estimators are proved. Simulations are performed for comparing the small sample properties of the proposed estimators under use condition of accelerated life test.

• Proceedings of the Korean Reliability Society Conference
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• 2001.06a
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• pp.91-97
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• 2001

These Study are for the development of the reliability assessment test code and test equipment and test procedures of the heavy sluice gate hydraulic cylinder. Because there is no reliability test code for the heavy sluice gate hydraulic cylinder inside and outside of the country, the modified reliability test code is made reference for the related existing standards like as ISO, JIS, MIL, TUV, DIN, KS and etc. In this study, the novel method is proposed to evaluate efficiency of the heavy sluice gate hydraulic cylinder on the loading conditions and established the conditions of the acceleration life test to reduce the testing time and cycles. The testing equipments for life test, lode operating test, high and low temperature test and salt spray test have been established for 8 month, and the reliability tests are accomplished. The test results of the heavy sluice gate hydraulic cylinder which is produced and tested initially in Korea are satisfied the durability life cycle on the using conditions.

• Journal of Applied Reliability
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• v.17 no.2
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• pp.136-142
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• 2017

Purpose: In this paper, we propose a test method for evaluating the life time of the inverter which is one of the main internal configuration systems in order to evaluate the life time of the power supply for the vehicle. Methods: The performance and failure criteria required for the development of the accelerated life test method were established and the Taguchi method was used to derive the stress factors affecting performance and reliability. Results: The major stress of the product degradation were considered to be high temperature. Conclusion: The acceleration factor was estimated through a two-level high temperature test and a test methods was designed to guarantee the accelerated life time of the inverter.

• Proceedings of the Korean Reliability Society Conference
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• 2011.06a
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• pp.281-288
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• 2011

Hydraulic hose assemblies deliver a fluid power in various oil pressure equipments such as construction machinery, automobile, aircraft, industrial machinery, machine tools, and machinery for ships, or they are used as pipes in oil pressure circuit. However, as the traditional measure for estimating life under the influence of various external factors incurs hardship in terms of time and expenses, it is essential to take accelerated life test by choosing the factor that suits the usage condition of the test object. The objective of the this study is to propose a acceleration model that takes both temperature and pressure without flexing condition into consideration. The life that is calculated by the equation for evaluating life and the test data show similar slopes as a result of comparing and analyzing the equation for evaluating life that is obtained in this research and the test data, which illustrates that they estimate life similarly, and the proposed equation is proved to be an accelerated life equation that presents the test results.

• Journal of Applied Reliability
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• v.11 no.3
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• pp.281-291
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• 2011

This paper presents an accelerated life test of booster pump for home water purifier. The failure analysis shows that decreased flux due to the plastic deformation of bypass spring adjusting pressure is the predominant failure mechanism. An accelerated life test is designed and implemented to estimate the lifetime of the booster pump. Temperature, water pressure and voltage are selected as accelerating variables through the technical review about failure mechanism. It is assumed that the lifetimes of booster pumps follow lognormal distribution and the combination model of temperature and non-thermal stresses holds. The life-stress relationship, acceleration factor, and $B_{10}$ life at design condition are estimated by analyzing the accelerated life test data.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.8
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• pp.438-442
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• 2013

The alternative refrigerant R436B is applied, to assess the application feasibility for a commercial cooling water system. The characteristic stability was verified by Sealed glass tube test and Autoclave test. R436B is chemically stable with the compressor material. The Oil miscibility test shows the usual compressor oil mixed well with R436B. Through the life acceleration test, the cooling performance is maintained. Though slight changes in oil and capillary tube diameter were found, they were within the permitted range. R436B should be applied to commercial cooling water systems as a simple replacement for the usual refrigerant.

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.693-697
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• 2005

This study was performed to develop accelerated life test method of the wind-turbine gearbox using accumulated damage theory that used to model the fatigue of parts that receive variable load. The accumulated damage theory was introduced, and the estimation of life and calculation of accelerated life test time was illustrated. As the actual application example, accelerated life test method of the gearbox was described. Life distribution of the wind-turbine gearbox was supposed to follow Weibull distribution and life test time was calculated under the conditions of average life (MTBF) 140,600 hours and 99% reliability for one test sample According to the accumulated damage theory, because test time can shorten in case increase test load, test time could be reduced by 1.2 years when we put the load 1.2 times of rated load than 0.93 times of rated load that is equivalent load calculated by load spectrum of the wind turbine. This time, acceleration coefficient was 21.3. This accelerated test method was used to develop accelerated test method of gear reducer, gear and bearing as well as the industrial gearbox and it is considered to be applied comprehensively to mechanical parts the fatigue of which is happened by load or pressure etc.

• 연구논문집
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• s.32
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• pp.35-43
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• 2002

This study was performed to develop accelerated life test method of machanical parts using cumulative damage theory that used to model the fatigue of parts that receive variable load. The cumulative damage theory was introduced, and the estimation of life and calculation of accelerated life test time was illustrated. 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% reliability for one test sample. According to the cumulative damage theory, because test time can 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. This accelerated test method was used to develop accelerated test method of gear reducer, hydraulic hose and bearing as well as agricultural tractor transmission and it is considered to be applied comprehensively to machanical parts the fatigue of which is happened by load or pressure etc.