• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1259-1264
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• 2008

This paper presents an accelerated life test for burn out of tungsten filament of automotive halogen lamp. There are many failure modes and failure factors that associated with tungsten filament. But in this explain the dominant failure mode of tungsten filament is the bumout of the filament failure. At first, over voltage, high temperature, inrush current and vibration are selected as stress factors by using of two stage Quality Function Deploymeng(QFD). And we planed accelerated life test that has one factor(voltage) and three levels. By experiment it has absorbed that over voltage has an effect on the life of halogen lamp. Using ALTA programs, we estimated the common shpae parament of Weibull distribution, life-stress relationship and $B_{100p}$ life.

• Journal of Applied Reliability
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• v.16 no.3
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• pp.238-244
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• 2016

Purpose: Domestic electric railway Regenerative Energy Storage System seriously affects the maintenance cost of the total operating expenses of nearly 60% of the total LCC (Life Cycle Cost) due to high dependence on foreign Leading company. Therefore by developing the system, it is important to lower the maintenance cost in the domestic supply. This study about the capacitor Reliability test and the purpose of this study is development electric railway Regenerative Energy Storage System. Methods: In case of, having a close relation between the temperature and the reaction rate, Accelerated Model was known that according to Arrhenius' law of chemical activity. If you apply this formula in using allowable temperature range of the capacitor can induce the Arrhenius empirical formula used in much Manufacture Fields. We evaluate the capacitors Leading company through the Arrhenius model. in order to providing a base for the localization of Ultra Capacitor. Conclusion: In this paper, we conducted a reliability test. And it was performed by the accelerated life test and Cycle Test with temperature and C-rate. and then MTBF and B10 life are estimated by analyzing the accelerated life test result. This is thought to need detailed study applying complex stress than about whether it matches the actual behavior in electric railway.

• Journal of Applied Reliability
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• v.17 no.4
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• pp.355-361
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• 2017

Purpose: The purpose of this research is to establish the life test method for ceramic heater and identify the failure mechanisms. Methods: We do accelerated life test in the condition of thermal shock and failure analysis for failed samples. Conclusion: The main failure mechanisms of ceramic heater are identified as overstress failure mechanisms as results of failure analysis and the shape parameters of weibull distribution by accelerated life test are identified as 0.8, 1.2 and 0.4 each at $400^{\circ}C$, $600^{\circ}C$ and $900^{\circ}C$. At $900^{\circ}C$, the shape parameter 0.4 means that It is exactly initial failure caused that the stress exceeds the strength of ceramic heater highly and the shape parameters 0.8, 1.2 at $400^{\circ}C$, $600^{\circ}C$ means that the shape parameters are around 1.0 so that the main failure mechanism is overstress failure which is same result as failure analysis. It means that the appropriate life test method for ceramic heater is reliability qualification test method rather than accelerated life test.

• Journal of the Korean Data and Information Science Society
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• v.5 no.2
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• pp.87-94
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• 1994

In this paper, we consider optimum plan to determine stress change times under the three-step stress PALTs, assuming that each test units follows an exponential distribution. The tampered random variable(TRV) model for the three-step stress PALTs setup are introduced, and maximum likelihood estimators(MLEs) of the failure rate and the acceleration factors are obtained. The change times to minimize the generalized asymptotic variance(GAVR) of MLEs of the failure rate and the acceleration factors are proposed for the three-step stress PALTs.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.9
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• pp.831-837
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• 2015

Many persons and electronic devices are exposed to electromagnetic (EM) waves generated from magnetic resonance imaging (MRI) equipment, EM pulses (EMPs), and many other kinds of EM wave devices. Finger strips are used to provide shielding from these EM waves. Because of the high thermal conductivity of finger strips, they are used in the design of specialized doors that are installed in shielded rooms. In this study, we perform an accelerated life test using the load acceleration stress, which affects the main failure mode of finger strips. We predict the life of the finger strip under normal usage conditions based on the results of the accelerated life test. We compare the results with those predicted from the life test under normal usage conditions to evaluate the validity of accelerated life testing.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.2_spc
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• pp.237-245
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• 2020

Metal seals are the main components that establish the containment boundary in bolted casks, which store spent nuclear fuel. These seals are degraded by heat and radiation. In addition, creep occurs when the seals are exposed to intense heat for an extended period. This creep results in the stress relaxation of the seals, which consequently impairs the seal integrity. The stress relaxation can reduce the sealing performance of the metal seal, which can further cause leakage in the storage cask. Moreover, the reduction of bolt tension leads to sealing performance degradation. In this study, the results of high-temperature-accelerated tests were obtained to evaluate the containment integrity of metal seals and the decrease in bolt tension. During the tests, the leakage rate, bolt strain, and ambient temperature of the metal seals were measured and analyzed. The metal seals were found to maintain containment integrity for 50 years of storage. The validity of the acceleration test was also investigated.

• Journal of Korean Society for Quality Management
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• v.24 no.3
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• pp.37-49
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• 1996

For highly reliable devices it is often defined to "fail" when its performance degrades below a specified value. In this paper we consider a method for optimally designing accelerated degradation tests(ADTs) in which the performance over exposure time and stress has Weibull distribution. For the product whose performance has Weibull distribution, the optimum plan - low stress level and sample proportions allocated to each test condition - is obtained, which minimize the asymptotic variance of maximum likelihood estimator of a stated quantile at design stress. We also present compromise ADTs plan that can be used for the practical purpose.

• Steel and Composite Structures
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• v.17 no.2
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• pp.145-157
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• 2014

This study aimed to investigate the fatigue crack growth behavior of a kind of fiber metal laminates (FML) under four different stress levels. The FML specimen consists of three 2024-T3 aluminum alloy sheets and two layers of glass/epoxy composite lamina. Tensile-tensile cyclic fatigue tests were conducted on centrally notched specimen at four stress levels with various maximum values. A digital camera system was used to take photos of the propagating cracks on both sides of the specimens. Image processing software was adopted to accurately measure the length of the cracks on each photo. The test results show that: (1) a-N and da/dN-a curves of FML specimens can be divided into transient crack growth segment, steady state crack growth segment and accelerated crack growth segment; (2) compared to 2024-T3 aluminum alloy, the fatigue properties of FML are much better; (3) da/dN-${\Delta}K$ curves of FML specimens can be divided into fatigue crack growth rate decrease segment and fatigue crack growth rate increase segment; (3) the maximum stress level has a large influence on a-N, da/dN-a and da/dN-${\Delta}K$ curves of FML specimens; (4) the fatigue crack growth rate da/dN presents a nonlinear accelerated increasing trend to the maximum stress level; (5) the maximum stress level has an almost linear relationship with the stress intensity factor ${\Delta}K$.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.2
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• pp.215-223
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• 2012

A violet smoke hand grenade(KM18) is used to generate signals. The grenade is considered to fail when its smoke emission time is longer than the specified one so that its smoke concentration becomes lighter. Accelerated degradation test for the grenade was performed, and then failure in smoke emission time was reproduced from the test. Stress for the degradation test was selected as temperature/humidity from the pre-test results. Degraded data of emission time from the accelerated test were analyzed through applying a distibution-based degradation model. Then, Peck Model was applied to predict the storage life under field conditions. In addition, the predicted storage life was compared with that of ASRP(Ammunition Stockpile Reliability Program).

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.47
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• pp.1-10
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• 1998

Testing high reliability devices under nomal operating condition is difficult, because the devices are not likely to fail in the relatively short time available for tests. For most applications it is necessary to accelerate the causes of failure by increasing a stress above its nomal value. Previous accelerated life test(ALT) plans have shown how to find optimum allocation, lowest stress and sample size subject to minimizing the variance of mean life estimator. In these ALT plans, the highest acceptable test-stress was assumed to be specified in advance by the experimenter but there is no guidance for selecting it. This assumption is, however, inappropriate for many applications. Testing devices at too-high stress levels can invalidate the extrapolation model, or introduce failure mechanisms that are not anticipated under nomal operating conditions. In this paper, we propose new 4:2:1 compromise plans using Min-Max method to minimize this risk and present minimized test-stress levels(max, middle, min), and find sample allocation based on Min-Max 4:2:1 compromise plans. In result, we compare previous 4:2:1 compromise plans specified maximum test-stress with Min-Max 4:2:1 compromise plans minimized maximum test-stress.