• 한국신뢰성학회지:신뢰성응용연구
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• 제12권3호
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• pp.131-138
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• 2012

A design of reliability qualification test based on performance distribution is developed. In general, the performance of an item degrades as the time goes by and the failure of an item occurs when the performance degradation reaches the pre-determined critical level. This article considers the reliability qualification test based on a more tightened critical value at the earlier stage to reduce the evaluation testing time and cost. A numerical example is provided to illustrate how to use the developed reliability qualification test.

• 한국신뢰성학회지:신뢰성응용연구
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• 제11권3호
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• pp.225-234
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• 2011

In the fields of reliability application, the most commonly used test methods for reliability qualification are zero-failure acceptance tests since they require fewer test samples and less test time compared to other test methods that guarantee the same reliability with a given confidence level. Usually values of shape parameters are assumed to be known in designing reliability qualification tests for Weibull lifetime distribution. It is important to select correct values of shape parameters to guarantee the specified reliability with given confidence level exactly. The effect of using wrong values of shape parameters in designing reliability qualification test for products with Weibull lifetime distribution is examined and selecting proper values of shape parameters for conservative reliability qualification is discussed.

• 한국신뢰성학회지:신뢰성응용연구
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• 제10권1호
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• pp.1-9
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• 2010

In general, the performance of a component degrades as time goes by and failure of a component occurs when the performance degradation reaches a pre-specified level. It is difficult to obtain the failure time distribution data or the necessary number of failure data especially for the metal or machine part. Thus, a design of reliability qualification test based on performance distribution is more effective than failure time distribution. In this study, a performance-based reliability qualification test is developed and a numerical example is provided to illustrate the use of the developed reliability qualification test. This approach could be applied to many kinds of metal or machine part whose magnitude of strength could not be evaluated during at any random points but judgement can be made by only failure of the part. Besides, it is also possible that any parts which have a similar failure characteristics could be applicable to the developed reliability qualification test.

• 동력기계공학회지
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• 제16권3호
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• pp.44-50
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• 2012

The reliability qualification test is essential in order to ensure the life time of the product under the normal operation conditions when a new product is developed. The reliability qualification test period has an important impact on the development time of new product. Therefore, some researches to reduce the test time of reliability qualification test have been actively studied. Generally, accelerated life test is well known as one method that can save the test time of the reliability qualification test. This test is conducted under the higher stress condition than normal condition. So we need to investigate what factor affects to the higher stress condition. This paper shows the relationship between the acceleration factor and reliability qualification test period. Especially, we focused on the method to obtain effective acceleration factors under the high temperature condition. Through some experiments for a refrigerator's compressor, we were able to confirm how to increase acceleration factors and how to reduce the reliability qualification test period with minimum samples.

• 신재생에너지
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• 제16권4호
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• pp.49-64
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• 2020

Photovoltaic and Thermal collector (PV/T) systems are renewable energy devices that can produce electricity and heat energy simultaneously using solar panels and heat exchangers. Since PV/T systems are exposed to the outdoors, their reliability is affected by various environmental factors. This paper presents a reliability test for a PV/T system and evaluates the test results. The reliability assessment entails performance, environment, safety, and life tests. The factor that had the greatest influence on the life of the system was the hydraulic pressure applied to the heat exchanger. A test was conducted by repeatedly applying pressure to the PV/T system, and a reliability analysis was conducted based on the test results. As a result, the shape parameter (β) value of 5.6658 and the B10life 308,577 cycles at the lower 95% confidence interval were obtained.

• 품질경영학회지
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• 제39권1호
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• pp.71-77
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• 2011

In the fields of reliability application, the most commonly used test methods for reliability qualification are zero failure tests since they require fewer test samples and less test time compared to other test methods that guarantee the same reliability with a given confidence level. An economic zero failure test plan is developed that minimizes the total cost related to perform a life test to guarantee a specified reliability of a product with a given confidence level and a numerical example is provided to illustrate the use of the proposed test method.

• 한국신뢰성학회지:신뢰성응용연구
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• 제16권2호
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• pp.125-133
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• 2016

Purpose: The purpose of this study is to evaluate durability of platform safety step system in railway. Method: We performed finite element analysis & durability analysis of platform safety step system with VPD (Virtual Product Development) techniques and examined the durability standard & qualification life through the rig test during no failure test time in reliability qualification test. We continued to test 1 million cycles in KRS (Korea Railway Standard) for system's robust design performance. Result: FEM analysis results are 14.9MPa & 14.7MPa of pin-joint, pivot and durability analysis result is above 1 million cycles. we calculated theoretically no failure test time 855,000 cycles and through the 1 million cycles durability rig test in KRS standard we confirmed product quality. Conclusion: This platform safety step system was designed very safe in terms of a mechanical strength & durability.

• 대한기계학회논문집A
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• 제39권4호
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• pp.397-403
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• 2015

본 논문은 개발 중에 있는 굴삭기 무인조종 로봇을 대상으로 시스템 신뢰도 평가 방법을 제안하고, 제안한 방법을 이용하여 수행한 신뢰도 보증시험에 대한 결과를 나타낸다. 로봇 시스템은 위험한 작업환경에서 작업자의 안전을 위하여 개발되었으며 전체 시스템의 신뢰도는 각 구성품의 신뢰도로부터 계산될 수 있다. 따라서 세 가지 주요 구성품 각각에 대한 전용 시험 장비를 제작하여 가속수명시험에 사용하였다. 가속수명시험 결과를 이용하여 신뢰수준에 따른 보증할 수 있는 평균수명을 추정하고, 적은 시료 수를 사용하는 시스템 신뢰도 보증 시험법을 제안하였다.

• 한국의료질향상학회지
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• 제21권1호
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• pp.12-31
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• 2015

Objectives : The purpose of this study was to develop the qualification system for training of Quality improvement professionals who work for improving patients' safety and healthcare quality. Methods : Based on the various laws and regulations, and the operational status of other professionals' qualification systems, a basic plan of professional qualification system of QI was drawn. And through meetings with QI experts, the final scheme of the concrete qualification system was developed. Results : For management of professionals's certification or qualification, fairness and reliability are important. To do this, setting the official standard, providing a standardized training program and having appropriate qualification test are required. In order to operate the qualification system strategically, 1) the introduction step, 2) dissemination and expansion step, and 3) fusing step should be considered. As a governing body for QI specialists' qualification, 'QI professionals' qualification Center (tentative)' must have the committee to assure fairness, professionalism, and reliability. In addition, 'QI Experts Certification Department (tentative)" to develop standards for the qualification tests and conduct the tests program,' QI experts Education Department (tentative name)" must be able to operate and maintain the QI training for professional qualifications. QI professional qualification exam must be taken by everyone regardless of age, gender, race, occupation, education, and work experience. The examination should include management, leadership, strategic planning and design, quality management, health care information, patient safety culture. Practical training courses can have three step programs; beginning, intermediate and special level. Conclusion : The QI qualification system need strategic approaches for the experts working for healthcare quality improvement and patient safety. It should include the program of standardized contents and test, and operating protocol of the qualificaton system.

• 한국신뢰성학회지:신뢰성응용연구
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• 제13권3호
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• pp.165-174
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• 2013

Thruster break for aerogenerator performs a role that is stopping the rotor in case of emergency such as strong wind, system abnormality or maintenance check. In this study, failure analysis and test evaluation on the thruster break for aerogenerator are proposed, and the entire process to improve reliability of the product through design improvement is presented. The typical failure case is fatigue and wear, and failure cause on these are identified and improvement plan is presented. Lastly, reliability improvement is established to analyse test results before after the life test.