• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.266-275
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• 2018

Herein, a novel operating life (OL) test method was evaluated with 200 mAh pouch-type lithium-ion batteries. By combining the calendar life (CL) test with intermediate pulse power cycling, more realistic life prediction was possible, which encompassed real operation of batteries accompanying with thermal acceleration. Larger capacity decrease and resistance increase of pouch cell were observed in the OL test, which was well explained using the SEI film growth model. After dissemble of pouch cell, capacity loss and resistance increase mostly occurred within anode, reflecting that SEI film growth on anode surface was highly attributable to cell degradation.

• 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 Electrical Engineering and Technology
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• v.2 no.2
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• pp.188-193
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• 2007

Magnetic contactors (MCs) are widely used in industrial equipment such as elevators, cranes and factory control rooms in order to close and open the control circuits. The reliability of MCs mainly depend on mechanical durability and international standards such as IEC 60947-4-1, which stipulates the testing method for MCs. Testing time, however, is so long in usual cases that a method of reducing testing time is required. Therefore, a temperature and voltage-accelerated life testing (ALT) method has been developed to reduce the testing time in this work. The accelerated life test data are analyzed and acceleration factors (AFs) are provided.

• Journal of Applied Reliability
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• v.8 no.2
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• pp.75-85
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• 2008

In this paper, we compared domestic with foreign pilot lamps installed on the instrument board or electronic modules (car audio, air-conditional system, etc.) of an automotive vehicle by an accelerated life test in order to estimate the life of domestic pilot lamps. An accelerated life test method was developed and the relation of the life and voltage stress was analyzed. The main results are as follows; i) $B_{10}$ life of pilot lamp is above 5,000 hours, vehicle travel time for 10 years. ii) the life of domestic pilot lamp is longer than that of foreign thing. iii) the life distribution of domestic pilot lamp is wider than that of foreign thing. iv) it is possible to promote import replacement of automobile pilot lamp.

• Journal of Fisheries and Marine Sciences Education
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• v.20 no.3
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• pp.452-461
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• 2008

The aim of this study is to survey and analyze the recognition of teachers and students about methods for entering general high school. For this study, firstly current methods for entering general high school of 16 offices of education were compared and analyzed. Secondly recognition of teachers in middle school or high school and of students in middle school about methods for entering general high school were surveyed and analyzed. Major consequences of this study are as follows: Firstly, most teachers preferred the method by both school life records and the entrance test but most students preferred the method by school life records. Secondly, teachers recognized the difference of school life records according to sex and school and the decrese of academic achievement from decrese of motive for studies as serious problems of general high school entrance method by school life records. Thirdly, students recognized competition among students in the same school and the difference of school life records according to sex as serious problems of general high school entrance method by school life records.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1221-1229
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• 2014

This paper proposes an approach for predicting the fatigue life of a propeller shaft of a forklift truck by an accelerated life test method. The accelerated life test method adopted in this study is the calibrated accelerated life test, which is highly effective in the prediction of the lifetime and enables significant reduction of the test time as well as a quantification of reliability in the case of small sample sizes. First, the fatigue test was performed under two high stress levels, and then, it was performed by setting low stress levels in consideration of the available test time and extrapolation. Major reliability parameters such as the lifetime, accelerated power index, and shape parameter were obtained experimentally, and the experimentally predicted lifetime of the propeller shaft was verified through comparison with results of an analysis of load spectrum data under actual operating conditions.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.407-410
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• 2007

In the RRH (Radio Remote Head) of a WCDMA Node B System, an HPA (High Power Amplifier) is used in order to amplify the transmission RF signal. Upon designing an HPA, the design requirements demand that the intermodulation characteristics are optimized during design and that the stability of the characteristics is maintained in the field. In this DOE (Design of Experiments) research, a few vital factors that affect intermodulation characteristics were first selected; then, an optimal solution was produced for high reliability in a noisy environment in the field by employing the Taguchi Method, a statistical method used for a robust design. Furthermore, by employing HALT(High Accelerated Life Test) during the verification test, this experiment has verified that an HPA that was designed using the Taguchi Method proved to be a far more robust design than an HPA that was designed without using the method.

• 연구논문집
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• s.34
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• pp.79-85
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• 2004

There are several types of life test method for hose assemblies. The two major tests used for hose assemblies are impulse test and burst test. And magnification adjustment of impulse pressure, heating of testing oil and repetitive motions of bending and straightening of testing hose are also performed for accelerating the life. According to the manufacture process of hose and swaging process of fitting, there is a difference in the life of hose assemblies from minimum 7 times to maximum 40 times during the life test in the same functioning condition. Like this, the life test of hose which has a wide scope of life distribution gives a problem that observation should take a long time to find out the existence of the bursting from the beginning of the test to the completion of bursting of hose assemblies. Therefore, this research proposes a process of concentrating on the defective section of hose assemblies and maximizing the life acceleration by giving 'Knockdown stress' to hose assemblies just until before the hose assemblies get out of order.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1989.10a
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• pp.59-64
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• 1989

On this condition of steel bridge member having a crack, occasionaly it is improssible to measure of stress history and to extract test specimen. Under this situation, tried to estimate remaining service life from statistical data on traffic and existing results of fatigue test without measuring of stress history and fatigue test. The main results are as following (1) Stress history of simple beam estimated from Montecallo simulation method with probabilistic model of traffic can be use to estimate remaining fatigue life instead of measuring of stress history. (2) In such a case measuring of remaining fatigue life at bridge member haying a crack, influences of RMS model and RMC model on fatigue crack growth rate are not differ without difference of applied stress range. (3) Application of cut off method may be overestimate remaining fatigue life.

• Journal of Families and Better Life
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• v.14 no.4
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• pp.219-232
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• 1996

This study was investigated the perceived level of stress and the coping method which the adolescent were confronting. The subject of this investigation was high school students who resided in the City of Pusan. Life Event Scale and Coping Methods Scale were used as the methods for examination. The data were analyzed using M, SD, t-test one-way ANOVA scheffe-test and Pearson's correlation related with this study problem were tested. The results of this study are as follows: 1. The perceived level of teenager's stress was little low with M=1.65 When dividing sphere of perceived level the stress by school problem was the highest and the circumstance problem personal one family one and a companion one are followed in regular sequence. 2. It was found that degree of stress made a difference according to the sex course grade school year religion parents's presence or absence SES the satisfactory degree of school life the satisfactory degree of school life the satisfactory degree of home life and the rearing attitude of parents. 3. As the coping score of teenager's stress was M=2.54. The short-term coping method was higher compared with the long-term one regarding coping methods. 4. It was found that the coping method of stress differed from each other according to variables of sex school year the satisfactory degree of school life and the satisfactory degree of home life. 5. It was found that the perceived level of stress had negative correlation with the coping method and especially long-term coping method had higher negative correlation.