• Journal of Applied Reliability
• /
• v.11 no.3
• /
• pp.267-279
• /
• 2011

LEDs have been used extensively in the mobile device, automobile, and general lighting because they are semi-permanent, long life, less power consumption, reliable and environmentally friendly. In this paper, the accelerated degradation test(ADT) for a general lighting 4W LED Lamp using external converter is considered. The conditions of ADT are high temperature and high humidity. We show that its life time is log-normally distributed with same parameters under both a normal condition and an accelerated condition, and also derive an accelerated factor.

• Journal of Applied Reliability
• /
• v.3 no.2
• /
• pp.103-116
• /
• 2003

We carry out reliability tests and investigate the failure mechanisms. of the wafer level vacuum packaged MEMS gyroscope sensor using an accelerated degradation test. The accelerated degradation test (ADT) is used to evaluate reliability (and/or life) of the MEMS vacuum package and to select the accelerated test conditions, which reduce the reliability testing time. Using the failure distribution model and stress-life model, we are able to estimate the average life time of the vacuum package, which is well agreed with the measured data. After improving several package reliability issues such as prevention of gas diffusion through package, we carry out another set of accelerated tests at the chosen acceleration level. The results show that reliability of the vacuum packaged gyroscope has been greatly improved and can survive without degradation of performance, which is the Q-factor in gyroscope sensor, during environmental stress reliability tests.

• Journal of Applied Reliability
• /
• v.16 no.3
• /
• pp.180-191
• /
• 2016

Purpose: The purpose of this study was to develop the accelerated life test method for Constant Electrical Potential Electrolysis gas sensor (CEPE gas sensor). Methods: The parts and modules of CEPE gas sensor were analyzed by using Reliability Block Diagram (RBD). Failure Mode and Effect Analysis (FMEA) and Quality Function Deployment (QFD) methods were performed for each part to determine the most affecting stress factor in its life cycle. The long term testing was conducted at three different dry heat levels and the acceleration factor was developed by using Arrhenius relationship. Conclusion: The acceleration factor for CEPE gas sensor was developed by using FMEA, QFD, and statistical analysis for its failure data. Also qualification tests were designed to meet the target life.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.7 s.238
• /
• pp.921-929
• /
• 2005

This paper presents an accelerated life test for burnout of tungsten filament of incandescent lamp. From failure analyses of field samples, it is shown that their root causes are local heating or hot spots in the filament caused by tungsten evaporation and wire sag. Finite element analysis is performed to evaluate the effect of vibration and impact for burnout, but any points of stress concentration or structural weakness are not found in the sample. To estimate the burnout life of lamp, an accelerated life test is planned by using quality function deployment and fractional factorial design, where voltage, vibration, and temperature are selected as accelerating variables. We assumed that Weibull lifetime distribution and a generalized linear model of life-stress relationship hold through goodness of fit test and test for common shape parameter of the distribution. Using accelerated life testing software, we estimated the common shape parameter of Weibull distribution, life-stress relationship, and accelerating factor.

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.136-141
• /
• 2004

The gear in various mechanical components easily occurs at damages by the external torque. The main failure modes of the gear are surface pitting with the tooth surface and breakage with tooth root by caused fatigue. Therefore, the gear is very important role in the reliability research since it may cause fatal damage of entire system such as the gear box in automobile transmission. In this study, the failure mode of the gear was analyzed and accelerated durability analysis was employed for the life estimation of spur gears. In the case of assumed load spectrums, the reliability of spur gears was evaluated by inverse power law-Weibull accelerated life test model with cumulative damage exposure.

• Journal of Applied Reliability
• /
• v.5 no.2
• /
• pp.273-287
• /
• 2005

Accelerated life test models and procedure are developed to assess the reliability of Refrigerator door switch. The main function of door switch is to operate bulb lamp and fan motor in the refrigerating room. The accelerated life test method and test equipments are developed using the relationship between stresses and life characteristics of the products. Using the developed accelerated life test method, the parameters of the ALT model and life time distribution are estimated and the reliability of the Door S/W at use condition if assessed. The proposed accelerated life test method and procedure may be extended and applied to testing similar kinds of products to reduce test time and costs of the tests remarkably.

• Proceedings of the Korean Fiber Society Conference
• /
• 2007.11a
• /
• pp.385-386
• /
• 2007

• Journal of Korean Society for Quality Management
• /
• v.25 no.3
• /
• pp.1-10
• /
• 1997

In the context of accelerated life tests, procedures are given for estimating the parameters in the modified Arrhenius model and for estimating mean life at a given future stress level. The conditional confidence intervals are obtained by conditioning on ancillary statistics and pivotal quantity. Using the data of Tobias and Trindada(1986), we illustrate conditional confidence interval for parameters under use condition in the modified Arrhenius model.

• Communications for Statistical Applications and Methods
• /
• v.6 no.2
• /
• pp.423-432
• /
• 1999

Accelerated life testing of product is commonly used to reduced test time and costs. In this papers is considered when the product is a two component system with lifetimes following the bivariate exponential distribution of Sarkar(1987) using inverse power rule model. Also we derived the maximum likelihood estimators of parameters for asymptotic normality. We compare the mean square error of the proposed estimator for the life distribution under use conditions stree through Monte Carlo simulation.

• Journal of Korean Society for Quality Management
• /
• v.23 no.4
• /
• pp.128-147
• /
• 1995

An accelerated life testing(ALT) for aluminum electrolytic capacitors is conducted and analyzed. A testing equipment, which consists of part fixtures, relay board, controller, video bridge and microcomputer, is made for the ALT. Load factors are temperature with four levels and voltage with three levels. Base on 'optimized 4:2:1 plan', 2,000 electrolytic capacitors are allocated at 12 experimental conditions(; 4 levels of temperature ${\times}3$ levels of voltage), and the ALT is conducted. From the experimental results, an acceleration model is derived and acceleration factors are estimated. A discussion on the experimental results is included.