• 한국신뢰성학회지:신뢰성응용연구
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• 제12권3호
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• pp.165-176
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• 2012

Hydrostatic bearing improves performance and life time of a product by avoiding solid friction and reducing viscosity friction with the help of creating pressure equilibrium between two faces doing relative motion. This study suggests failure analysis and test evaluation for a ball joint that adopts the hydrostatic bearing and introduces the entire process to improve reliability of the product by design improvement. A typical failure is growth of friction torque by solid friction, and its failure cause is determined and the improvement is proposed. Finally, reliability improvement is established by analysis of the results of before and after acceleration test.

• 한국신뢰성학회지:신뢰성응용연구
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• 제16권4호
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• pp.263-271
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• 2016

Purpose: A slurry pump for flue gas desulfurization system performs a role that discharges the slurry of a plaster shape in a thermal power plant. Since a slurry pump transfers the slurry by the centrifugal force, it has the friction wear in the impeller and liner because of the slurry. Methods: In this study, failure analysis and test evaluation on the slurry pump have been proposed and the process that reliability of the product improves through design improvement has been presented. And failure cause of typical failure case has been investigated and improvement design has been presented. Results: Reliability improvement is established by analysis of the test results of before and after acceleration test. Conclusion: This study can be provided to improve the product reliability through failure analysis of a slurry pump.

• Current Photovoltaic Research
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• 제2권3호
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• pp.140-145
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• 2014

The globally used PV qualification tests and reports the pass/fail only. Therefore, the reliability of new PV materials and parts can't be compared quantitatively with the reliability of the PV parts and materials in the market. Global PV materials and parts companies test and compare their materials, parts, and modules using the failure-to-test (FTT). However, it takes a long accelerated stress test (AST) until failure. It also needs to test the new and existing materials and parts. Therefore, it requires excessive equipment time and cost. In order to reduce the time and cost, a new reliability enhancement methodology has been developed. It tests the PV materials, parts, and modules in the global market and stores them in the PV reliability database. It reduces the time and cost of the comparison and enhancement of PV reliability. An example of the reliability enhancement of the PV encapsulant, EVA is presented.

• 한국신뢰성학회지:신뢰성응용연구
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• 제14권4호
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• pp.236-242
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• 2014

Since permanent magnet coupling transfers power by magnetic force without contact, it has little shock, vibration, noise. In case of overload, it protects a pump or a motor which is relatively important by slipping internally. In this study, failure analysis and test evaluation on the permanent magnet coupling have been proposed and the process that reliability of the product improves through design improvement has been presented. And failure cause of typical failure case has been investigated and improvement plan has been presented. Finally, reliability improvement is established by analysis of the test results of before and after acceleration test.

• 동력기계공학회지
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• 제16권6호
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• pp.59-65
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• 2012

Torque Generator is a product which has function to transform hydraulic energy to mechanical energy of torque and rotating speed, and be used for direction change device of agricultural machines. This study proposes failure analysis and test analysis on torque generator and introduces a process that reliability of a product is enhanced by design improvement. And also it presents improvements of maximum output torque by modifying design and surface treatment. Lastly it verifies reliability improvement by analyzing test results of before and after life test.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1498-1499
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• 2007

In general, ALT can be used to expect the lifetime of electric machines and accelerated stress testing(AST) is used to evaluate the residual life of insulation system. In this paper, a method to design the accelerated life testing(ALT) for reliability qualification of electrical apparatus is represented.

• 한국신뢰성학회지:신뢰성응용연구
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• 제14권2호
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• pp.93-96
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• 2014

RFID (Radio Frequency IDentification) system is recognition technology which can maintain various object's information. Reliability of RFID tags is the most important factor in RFID system. In this paper, we proposed ALT (Accelerated Life Test) method for UHF RFID tags. Temperature and humidity were adopted as stress factors and the accelerated life tests were conducted in three different conditions. We performed failure analysis for identifying failure mechanism and statistical analysis of test data. In the statistical analysis, we employed Inverse Power law for relationship between tag's life and stress. Through the statistical analysis, we proposed acceleration factor for several levels of temperature-humidity. The reliability qualification test plans were also designed for the tag's target reliability.

• International Journal of Railway
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• 제2권1호
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• pp.8-17
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• 2009

The wheelset, its functions and position under the train is the prime safety-critical component. Whether in design, qualification, manufacturing or maintenance, the wheels and axles have been the focus of special attention at SNCF for over 25 years and the French Railways are actively involved in various Research and Development work towards interoperability between the railways, railway reliability and running safety.

• 한국컴퓨터정보학회논문지
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• 제25권10호
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• pp.135-142
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• 2020

본 연구는 지각된 과잉자격이 영역초월행동과 직무성과에 미치는 영향을 제시하고자 한다. 본 연구의 목적을 달성하기 위하여 중국에 있는 VR기술을 개발하는 기업 연구원들을 대상으로 총 373부의 설문지를 수집하였다. 설문조사를 통해 수집된 데이터는 통계프로그램 SPSS V.22과 AMOS V.22를 사용하여 빈도분석, 신뢰도분석, 확인적 요인분석, 구조방정식 모델 등으로 분석하였다. 본 연구의 실증분석을 통해 확인된 연구결과는 다음과 같다. 첫째, 지각된 과잉자격은 직무성과에 부(-)의 영향을 미치는 것이다. 둘째, 구성원 지각된 과잉자격은 영역초월행동에 부(-)의 영향을 미치는 것이다. 셋째, 구성원의 영역초월행동은 직무성과에 정(+)의 영향을 미치는 것이다. 결론 및 토론 부분을 통하여 본 연구의 이론적 시사점, 실무적 시사점과 연구의 한계와 향후 방향에 대한 심도 있는 논의를 제시하였다.

• 한국전기전자재료학회논문지
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• 제27권6호
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• pp.343-349
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• 2014

It is summarized that potential causes of performance degradations and failure mechanisms of crystalline silicon photovoltaic (PV) modules installed in Middle East area. In addition, we also reviewed current PV module qualification test (IEC 61215) and the methods for detection of wear-out fault. The failure of PV modules in the extreme environmental conditions such as deserts is mainly due to high temperature, humidity, and dust storms. In particular, cementation phenomenon caused by combination of sand and moisture leads to rapid degradation in the performance of PV modules. In order to evaluate and guarantee the long term reliability of PV modules, specific qualification tests such as sand dust test, salt mist test and potential induce degradation test considering operating environment of PV module should be carried out.