• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2013.04a
• /
• pp.84-85
• /
• 2013

방염제품의 내구신뢰성은 국민의 화재 안전성 확보를 위한 필수 불가결의 요소로 이들 제품의 내구성능 예측은 방염성능의 지속적 유지를 위한 방염시설물 유지 관리 측면에서도 상당히 중요하다. 본 논문에서는 방염도료의 내구신뢰성 예측 및 확보를 위한 방염도료 가속수명법에 관한 연구로써, 방염도료의 고장 원인분석을 진행하였으며, 현장시험 및 현장 모사 실내 가속촉진시험을 진행하였다. 실내 가속촉진시험은 방염도료의 현장 주고장모드인 온 습도 사이클 시험으로 진행하였으며, 시험 척도로서 화학발광을 분석하여 적용하였으며 현장 데이터와 실내 촉진데이터와의 상관성 규명을 위하여 Mitab 등의 통계적 기법을 이용하여 고장유형 및 상관성을 규명하였다.

• Proceedings of the KIPE Conference
• /
• 2010.07a
• /
• pp.295-296
• /
• 2010

본 논문에서는 고속전철용 추진제어장치의 개발 및 본선 주행시험에 관한 내용을 소개하였다. 고속열차용 추진제어장치는 입력 전류의 고조파를 감소하기 위하여 단상 PWM 컨버터 2대가 병렬로 구성되고 인버터는 3상 인버터 1대로 구성된다. 추진제어장치의 전력회로를 간단히 구성하기 위하여 최대용량(4500V/4200A)의 IGBT 전력소자를 적용하였다. 3상 인버터는 가속시 스위칭 기어현상을 저감하기 위하여 저주파 동기 PWM 기법을 적용하였다. 추진제어장치의 성능을 평가하기 위하여 실제 차량이 운행될 본선에서 속도 300km/h까지 가속시험, 비상제동 시험, 구배기동 시험 등을 실시하였다. 시험을 통하여 제작된 추진제어장치가 성능사양을 만족함을 확인하였다.

• Korean Chemical Engineering Research
• /
• v.54 no.1
• /
• pp.6-10
• /
• 2016

Until a recent day, degradation of PEMFC (Proton Exchange Membrane Fuel Cells) has been mainly studied in unit cell. But operation and degradation of real PEMFC going along in stack instead of unit cell. Therefore in this work, ADT (Accelerated Degradation Test) of PEMFC was done in stack and the result from stack's test was compared with that of unit cell. The polymer electrolyte membrane was degraded by repeated electrochemical and mechanical degradation method among several ADT methods. Current densities of MEA at 0.6V decreased in stack and unit cell, 28.4% and 27.8% respectively after ADT for 312 hours. Hydrogen crossover current densities of membrane increased in stack and unit cell, 16.8% and 15.2% respectively after ADT for 312 hours. The result of ADT in stack was similar that of ADT in unit cell, which showed that ADT method of unit cell was available to the stack.

• Journal of the Microelectronics and Packaging Society
• /
• v.15 no.2
• /
• pp.55-61
• /
• 2008

This paper shows quantitative reliability evaluations of a Bluetooth module through extending previous qualitative methods limited to structure reliability tests and solder joint reliability tests for Bluetooth modules. Accelerated Life Testing (ALT) of the modules using temperature difference in temperature cycling as an accelerated stress was conducted for quantitative reliability evaluation under field environment conditions. Lifetime distribution parameters were estimated using the failure times obtained through the ALT, and then Coffin-Manson model was implemented. Results of the ALT showed that the failure mode of the modules was open and the failure mechanisms are both crack and delamination. The ALT reproduced the failure mode and mechanisms of failed Bluetooth modules collected from the field. Further, a quantitative reliability evaluation method with respect to various temperature differences in temperature cycling was proposed in this paper. $B_{10}$ lifetime of the module for the temperature difference $70^{\circ}C$ using the proposed method would be estimated as about 4 years.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.10
• /
• pp.997-1004
• /
• 2017

The life of elevator wire ropes is one of the most important characteristics of an elevator, which is closely related to the safety of users and its maintenance policy. It is not cost effective to measure the lifetime of elevator wire ropes during their use. In this study, the life estimation of elevator wire ropes (8x19W-IWRC) is considered using accelerated degradation test data. A bending fatigue tester is used to perform the accelerated degradation tests, incorporating the acceleration factor of tensile force. Assuming that the life of wire ropes is log-normally distributed, two life estimation methods are suggested and their results are compared. The first method estimates the life of wire ropes utilizing the accelerated life model with pseudo lives obtained from a linear regression model. The second method estimates the life using a logistic model based on failure probability.

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

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.1648-1651
• /
• 2007

The goal of this paper is to introduce two methods to determine a model for the accelerated factor equation for pneumatic cylinder according to the Black equation shape. The loads consist of working pressure and temperature and we adjust these two parameters to reduce the test time but keeping the true behavior of deterioration. The first part will introduce a method using accelerated factor coming from experimental results to determine the coefficient of the Black equation by the method of the least square theory. The second part will introduce another method based on various conditions of test with the assumption that the effect of temperature and the effect of pressure on the life of pneumatic cylinder are independent. In these two cases, the results are the unknown coefficients of the Black equation.

• The Korean Journal of Applied Statistics
• /
• v.13 no.2
• /
• pp.563-573
• /
• 2000

In this paper, we propose three estimators of Kullback-Leibler Information functions using the data from accelerated life tesb. 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.

• Journal of Digital Contents Society
• /
• v.15 no.2
• /
• pp.301-308
• /
• 2014

The mass storage of data and the importance of storage capacity lately has emerged. In this paper, we suggest the new method which estimate life cycle from acceleration life test about 2.5 inch hard disk driver as mass storage, which minimize the difference between real market annual failure rate and estimated failure rate. we obtain market transfer capacity per hours from returned 2.5inch hard disk drives about 309 numbers and accelerating transfer capacity per hours from acceleration life test. we calculate acceleration factor about duty cycle and estimate annual failure rate from failure rate and acceleration factors: temperature acceleration factor, duty cycle acceleration factor, the transfer capacity per hour represent the 93.4 % of user is 5.8 GB/hour, the transfer capacity per hour from acceleration life test is 81.4 GB/hour. the acceleration factor of duty cycle is 14.1. annual failure rate is stabilized at market one year after, annual failure rate is between 0.3 and 0.378. estimated annual failure rate is 0.4, so it is matched at 75~94 % between estimate annual failure rate and market annual failure rate. This study influence the estimate method of annual failure rate by the result of acceleration life cycle of manufacture.

• 한국데이터정보과학회:학술대회논문집
• /
• 2003.10a
• /
• pp.171-176
• /
• 2003

전기 설비의 가속 수명시험에서 절연재료의 열 수명 시험자료에 대한 통계적 분석지침으로 1987년 ANSI/IEEE Std. 101이 제정된 이래, 많은 실험의 결과 분석에 이용되어져 오고 있다. 그러나, ANSI/IEEE Std. 101 에서는 제한된 환경 하에서 얻어지는 소수의 자료를 분석에 이용하고 있어, 분석 결과의 정확성에 의문이 제기되고 있다. 본 논문에서는, ANSI/IEEE Std. 101에서 사용한 자료에서 얻은 통계량들을 근거로 Monte Carlo Simulation을 실시하여 분석지침에서 제시한 결과와 비교하여 보았다.