• 한국신뢰성학회지:신뢰성응용연구
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• 제17권4호
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• pp.355-361
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• 2017

Purpose: The purpose of this research is to establish the life test method for ceramic heater and identify the failure mechanisms. Methods: We do accelerated life test in the condition of thermal shock and failure analysis for failed samples. Conclusion: The main failure mechanisms of ceramic heater are identified as overstress failure mechanisms as results of failure analysis and the shape parameters of weibull distribution by accelerated life test are identified as 0.8, 1.2 and 0.4 each at $400^{\circ}C$, $600^{\circ}C$ and $900^{\circ}C$. At $900^{\circ}C$, the shape parameter 0.4 means that It is exactly initial failure caused that the stress exceeds the strength of ceramic heater highly and the shape parameters 0.8, 1.2 at $400^{\circ}C$, $600^{\circ}C$ means that the shape parameters are around 1.0 so that the main failure mechanism is overstress failure which is same result as failure analysis. It means that the appropriate life test method for ceramic heater is reliability qualification test method rather than accelerated life test.

• 대한기계학회논문집A
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• 제38권10호
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• pp.1171-1177
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• 2014

전자파차폐용 문세트는 기계적 강도 및 내구성과 전자파 차폐라는 전기적 성능 요구를 동시에 충족시켜야 하므로 이에 알맞은 신뢰성입증시험법의 정립이 요구된다. 특히 전자파 차폐 성능에 직접적인 영향을 미치는 핑거스트립이라고 불리는 베링륨동 재질의 박형 스프링 하위 부품은 문짝과 직접적인 반복 건조마찰이 발생하므로 내구성에 만전을 기해야 하는 부위인데, 산업계에서는 주기적인 보전이 필요한 이 핑거스트립의 교체주기에 대한 보증도 또한 필요한 실정이다. 이러한 요구들에 대응하여 본 연구에서는 전자파차폐용문세트의 시험항목들을 정하고 전체 시스템 수명뿐만 아니라 교체품의 교체주기에 대한 보증을 단순한 방법으로 동시수행하는 입증시험을 설계하였다. 결론적으로 하위 교체부품을 가지는 직렬 시스템의 신뢰성입증시험에서는 교체품의 교체주기에 대한 보증도 항상 함께 포함시킬 것을 제안한다.

• 한국항공우주학회지
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• 제30권8호
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• pp.94-102
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• 2002

위성은 일단 한번 발사하고 나면 운용궤도상에서 수리 및 회수가 거의 불가능하기 때문에 위성에 들어가는 모든 개발 부품들은 완벽한 설계, 충분한 해석, 고 작업도의 제작, 그리고 다양한 시험을 수반하여 충분한 검증을 받게 된다. 그럼에도 불구하고 실패가 일어날 수 있으며, 이러한 실패에 대비하기 위해 여분의 부품을 탑재하여 일부 부품의 실패에도 불구하고 정상적인 작동을 할 수 있도록 설계한다. 본 논문에서는 현재 전자통신연구원에서 개발중인 통신방송위성의 중계기에 대한 신뢰도 분석과 함께 어떠한 방법을 이용하여 여분의 부품을 구성하는 것이 신뢰도 측면에서 최적화되는 설계인지 분석하였다. 이를 위하여 여러 가지 여분의 부품을 구성하는 방법 및 각각의 경우에 대한 결과를 비교하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권3호
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• pp.186-195
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• 2000

In this paper, partial discharge (PD) measurement was performed to evaluate the quality of the cable joint and termination constructions. The resistive coupling technique for PD detection using resistivity of semiconducting layer of the cable in the accessories, such as joints and terminations. With high frequency PD (HEPD) measurement, an excellent sensitivity below 20pC could be achieved under unshielded condition. The localization of the defects in the accessories could be identified. During heating cycle, PDs were monitored and analyzed. At that time, the PDs were dependent on the temperature of the heating cycle and showed cyclic behaviors, which were attributed to local delamination of the interfaces, between epoxy unit and stress relief cone(SRC) and between SRC and cable, due to the difference of thermal expansion. As a conclusion, HFPD measurement technique was proven to be an effective diagnostic method for qualification of extra high voltage (EHV) cable accessories. With this technique, the optimal design of the components of the accessories could be verified not only in an early stage but also under operating condition. This technique would result in the improvement of the reliability of the EHV cable accessories.

• 근관절건강학회지
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• 제21권3호
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• pp.224-235
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• 2014

Purpose: The purpose of this study was to test the reliability and the validity of the Practice Environment Scale of Nursing Work Index (PES-NWI) scale when applied to Korean psychiatric nurses working in the psychiatric hospital in Korea. Methods: Data from 224 psychiatric nurses working in the 6 psychiatric hospitals in Korea were analyzed using Cronbach's ${\alpha}$, item total correlation, and exploratory factor analysis. Results: The Cronbach's ${\alpha}$ for the 27 items from the PES-NWI were .93, and the item total correlation coefficients ranged from .38 to .64. Six factors which explained 61.2 of variance in the perception of practice environment, emerged; nurse professional role and development, nurse manager ability, leadership, and support of nurses, staffing and resource adequacy, nursing foundation for quality of care, collegial nurse-physician relations, co-worker's ability and qualification. Five derived factors reconstructed, and two factors were renamed. Conclusion: Findings demonstrate that not all but 27 items from PES-NWI is a reliable and valid scale when applied to Korean psychiatric nurses working in Korea. Also findings indicate that Korean psychiatric nurses perceive practice environment differently than American nurses but have some point of similarities with Asian nurses working in the United States.

• 대한기계학회논문집A
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• 제39권12호
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• pp.1275-1280
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• 2015

카운터웨이트를 수명시험 하기 위해서는 실제 현장과 유사하게 2 톤의 무게를 가진시켜 주는 대형 가진기가 필수적이다. 그렇지만 이러한 장비를 일반업체에서 보유하여 시험하기는 어려우므로, 이러한 애로점을 해소하기 위해 본 연구에서는 첫번째로 2 톤의 중량물일지라도 건설기계의 신뢰성을 평가하는 전기터들로 구성되는 회전식 가진기를 사하여 실제 현장조건을 재현하는 시험장비를 개발하였고, 주요 구성품에 대해 카운터웨이트의 고장해석을 수행하였다. 두번째로 현장으로부터 필드데이터를 측정하여 수명시험에 활할 수 있도록 하였다. 마지막으로 성능과 수명을 확인하기 위해 가속수명시험법을 개발하였고, 제품의 고장발생 없이 $B_5$ 10,000 시간을 만족하는 가속수명시험을 완료하였다.

• 한국소음진동공학회논문집
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• 제15권6호
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• pp.652-659
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• 2005

In this paper, seismic qualification analysis for the Plant control Panel is carried out to confirm the structural integrity under the seismic conditions represented by required response spectra(RRS). The finite element method(FEM) is used for the analysis and a mode combination method is adopted to obtain a more reliable spectrum analysis results. In addition, the experimental analysis is performed to compare the reliability of the analytical results. The analysis results shows that the plant control panel system is designed to have the dynamic rigidity with no resonance frequency below 33 Hz. The analytically calculated maximum stress of the plant control panel system is $36\%$ of the field strength of material, thus it can be shown that the system has a stable structure for the seismic load.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.686-691
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• 2007

The ride comfort is more important according to train speedup. Generally it is defined as the vehicle vibration. There are many studies on evaluation method of ride comfort for railway. In the case of Korean high speed train(HSR 350x), the ride comfort has been assessed by statistical method according to UIC 513R. To verify the design requirements for the performance of HSR 350x, the qualification tests had been conducted from August 19, 2002 to December 2004 and the stabilization and reliability tests are carried out nowadays. Up to December 2006, total test runs and the accumulated milage of the train were 357 times and 164,000km, respectively. A total of 352 ride indices had been acquired through the on-line test from Aug. 2002 to Dec. 2006. In this paper, we have reviewed the characteristics of ride comfort for HSR 350x according to the operational conditions, such as load and track conditions, season and used time, by using the tests data.

• 산업경영시스템학회지
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• 제23권61호
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• pp.75-87
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• 2000

This paper proposes a procedure for designing an accelerated test using SMAT(Stress, (failure) Mechanism and Test) model describing the relation among stress, failure mode/mechanism and test method. In SMAT model the stresses to be applied are derived from the environmental factor analysis, the relative importance of those stresses can be estimated using AHP(Analytic Hierarchy Process) and failure mode/mechanism and test method are derived from the fields failure information and FMEA(Failure Mode and Effect Analysis). By applying the procedure we can make a selection of major factors to cause the failure of assembly and design the accelerated test using DOE(Design of Experiments) The procedure is illustrated with an qualification test case study of washing machine shaft assembly in "A" electric appliance company.

• Journal of Advanced Marine Engineering and Technology
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• 제30권5호
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• pp.562-571
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• 2006

Finite element analysis is performed to evaluate structural reliability of an automotive pedal arm under conditions of the stiffness, the load and the endurance test specifications. Results of the analysis shows that the pedal arm is safe enough under the tests. A topology optimization is numerically implemented, overall shape of the pedal arm being verified to be reasonable, A design concept to insert holes in the arm is established, which may be used to reduce its weight.