• Proceedings of the Computational Structural Engineering Institute Conference
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• 1994.10a
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• pp.71-78
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• 1994

The main objectives of the study may be stated as follows : \circled1 the acquisition of fundamental updated data for the assessment of aged wharf structures of pier type based on systematic static/dynamic load testing \circled2 the study of techniques and methods for field testing \circled3 realistic safety and load carrying capacity assessment based on practical reliability analysis. In this study field testing of real structure is performed and the results are compared with those of the 2D and 3D linear structural analysis. It may be seen that the practical reliability methods can be applied for the safety and capacity assessment of aged wharf structures of pier type.

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

• Journal of Applied Reliability
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• v.18 no.1
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• pp.8-19
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• 2018

Purpose: This study has developed the accelerated lifetime test method for smps for outdoor lighting LED through two factors of temperature and humidity. Methods: Acceleration condition was confirmed for each stress and model, and acceleration life test model was estimated according to acceleration condition. Results: As a result of confirming the accelerated life test model, in the case of humidity, acceleration was established only in the foreign products. Therefore, it is confirmed that the acceleration condition is insufficient. However, the estimated parameters for temperature are relatively constant. It is therefore suitable for power supply acceleration tests for outdoor lighting LEDs. Conclusion: The SMPS acceleration test for outdoor lighting LED can improve the availability of the product by developing an accelerated life test method that guarantees the reliability of the product.

• The Korean Journal of Applied Statistics
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• v.23 no.3
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• pp.573-584
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• 2010

This paper considers the differences in the software execution environments in the testing phase and the operational phase to determine the optimal release time and warranty period of software systems. We formulate equations for the total expected software cost until the end of the software life cycle based on the NHPP. In addition, we derive the optimal release time that minimizes the total expected software cost for an imperfect debugging software reliability model. Finally, we analyze the sensitivity of the optimal testing and maintenance design related to variation of the cost model parameters based on the fault data observed in the actual testing process, and discuss the quantitative properties of the proposed model.

• Journal of Applied Reliability
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• v.5 no.2
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• pp.221-239
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• 2005

General chip SMD parts(chip resistance, chip capacitor, chip varistor etc.) are very wide used electronics parts for IT units. But, failure modes are indistinct for these chip parts. In factory and field the failure modes are recognized to accidental failure mode caused by potential defect. In this paper used chip varistor ALT(Accelerate Life Test) test for verify general failure modes in chip SMD parts. Also the results are useful for general chip SMD ALT tests.

• Journal of Applied Reliability
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• v.17 no.1
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• pp.1-10
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• 2017

Purpose: This study aims at omitting the initial testing of the ASRP by determining the initial test year. Methods: This study is to determine of the initial test year for one-shot system using validity assessment of drugs. Results: Procedures for determining the initial test duration of the one shot system and examples of omitting the tests are presented. Conclusion: Using this method, the time and labor required for testing can be saved by omitting the initial testing of ASRP.

• International Journal of Reliability and Applications
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• v.7 no.2
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• pp.89-99
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• 2006

A new classes of life distribution, namely harmonic used better than aged in expectation in upper tail (HUBAEUT) is introduced. Testing exponentiality against this class is investigated using kernel method. The limiting null and nonnull distribution of the test statistics is normal and the null variance is calculated exactly. Selected critical values are tabulated for sample sizes of 5(1)40. Power of the test are estimated by simulation. the efficacies of the test statistics used for testing against HUBAEUT are calculated for som common alternatives and are compared to some other procedures. It is shown that proposed test is simple, has high relative efficiency and power for some commonly used alternatives. The set of real data are used as an examples to elucidate the use of the proposed test statistics for practical reliability.

• Proceedings of the Korean Reliability Society Conference
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• 2005.06a
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• pp.51-67
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• 2005

General chip SMD parts(chip resistance, chip capacitor, chip varistor etc.) are very wide sed electronics parts for IT units. But, failure modes are indistinct for these chip parts. In factory and field the failure modes are recognized to accidental failure mope caused by potential defect. In this paper used chip varistor ALT(Accelerate Life Test) test for verify general failure modes in chip SMD parts. Also the results are useful for general chip SMD ALT tests.

• Proceedings of the KIEE Conference
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• summer
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• pp.354-356
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• 2004

This paper is the transient analysis for choosing the optimal SCR ratings of AC3 utilization category testing equipment(AC3 TE) used for electrical durability test for magnetic switch according to IEC60947-4 Annex B by utilizing EMTP -ATPDraw. Magnetic contactor closes and opens the motor load with ON/OFF switch of electronic contactor. It is also used for protecting and controlling the load. Magnetic contactor detects the over-current flow in the load with a over-current relay and disconnects the load by opening its control power. The key cost of AC3 TE is the SCR ratings. The more decreases SCR ratings, the more decreased the cost is, but it is impossible to ensure the reliability. On the other hand, the more increases SCR ratings, the more increased the cost is. Thereupon, in this paper after the testing circuit is simulated by using EMTP-ATPDraw the SCR ratings will be applied in order to guarantee the testing reliability of PT&T(Power Testing and Technology institute in LG Industrial Systems Co.,Ltd.).

• Proceedings of the Korean Reliability Society Conference
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• 2002.06a
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• pp.273-273
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• 2002

In this paper, we investigate a software release policy with software reliability growth factor during the warranty period by assuming that the software reliability growth is assumed to occur after the testing phase with probability p and the software reliability growth is not assumed to occur after the testing phase with probability 1-p. The optimal release policy to minimize the expected total software cost is discussed. Numerical examples are shown to illustrate the results of the optimal policy. And we consider a Bayesian decision theoretic approach to determine an optimal software release policy. This approach enables us to update our uncertainty when determining optimal software release time, When the failure time is Weibull distribution with uncertain parameters, a bayesian approach is established. Finally, numerical examples are presented for illustrative propose.