• 한국품질경영학회:학술대회논문집
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• 한국품질경영학회 2004년도 품질경영모델을 통한 가치 창출
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• pp.85-89
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• 2004

This brief paper is an application of HALT(High Accelerated Life Test) and FA(Failure analysis) to improvement of STN LCD module. Before HALT the result of environmental test is good. So, we choose the technique of HALT to evaluate reliability. After HALT and Fa, we suggest some methods to improve reliability

• 산업공학
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• 제6권2호
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• pp.67-78
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• 1993

In this paper, we deal with the application of the fuzzy sets theory to evaluate and estimate the system reliability under the fault tree analysis. We formulate the uncertainty of component reliability to fuzzy sets, and propose a procedure for obtaining the system reliability in case the system structure is described by fault tree. An importance measure of each component is proposed. Computer program for fuzzy fault tree analysis(FFTA) is developed using C language to obtain the system reliability and the component‘s fuzzy importance.

• Structural Engineering and Mechanics
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• 제75권6호
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• pp.771-784
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• 2020

Reliability analysis techniques combining with various surrogate models have attracted increasing attention because of their accuracy and great efficiency. However, they primarily focus on the structures with continuous response, while very rare researches on the reliability analysis for structures with discontinuous response are carried out. Furthermore, existing adaptive reliability analysis methods based on importance sampling (IS) still have some intractable defects when dealing with small failure probability, and there is no related research on reliability analysis for structures involving discontinuous response and small failure probability. Therefore, this paper proposes a novel reliability analysis method called AGPC-IS for such structures, which combines adaptive Gaussian process classification (GPC) and adaptive-kernel-density-estimation-based IS. In AGPC-IS, an efficient adaptive strategy for design of experiments (DoE), taking into consideration the classification uncertainty, the sampling uniformity and the regional classification accuracy improvement, is developed with the purpose of improving the accuracy of Gaussian process classifier. The adaptive kernel density estimation is introduced for constructing the quasi-optimal density function of IS. In addition, a novel and more precise stopping criterion is also developed from the perspective of the stability of failure probability estimation. The efficiency, superiority and practicability of AGPC-IS are verified by three examples.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1130-1135
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• 2003

The need to increase the reliability of a structural system has been significantly brought in the procedure of real designs to consider, for instance, the material properties or geometric dimensions that reveal a random or incompletely known nature. Reliability based design optimization of a real system now becomes an emerging technique to achieve reliability, robustness and safety of these problems. Finite element analysis program and the reliability analysis program are necessary to evaluate the responses and the probabilities of failure of the system, respectively. Moreover, integration of these programs is required during the procedure of reliability based design optimization. It is well known that reliability based design optimization can often have so many local minima that it cannot converge to the specified probability of failure. To overcome this problem, barrier function method in reliability based design optimization is suggested. To illustrate the proposed formulation, reliability based design optimization of a bracket is performed. AMV and FORM are employed for reliability analysis and their optimization results are compared based on the accuracy and efficiency.

• 한국전문물리치료학회지
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• 제20권2호
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• pp.60-68
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• 2013

The purpose of this study was to assess the intra-rater test-retest reliability of tibial external rotation angle measurement using a smartphone-based photographic goniometer, DrGoniometer (DrG) compared to a three-dimensional motion analysis system (Vicon). The current study showed an interchangeable method using DrG to measure the tibial external rotation angle in standing knee flexion at $90^{\circ}$. Twelve healthy subjects participated in this study. A rest session was conducted 30 minutes later for within-day reliability and five days later for between-day intra-rater test-retest reliability. To assess the validity of the measurement using DrG, we used a three dimensional motion analysis system as a gold standard to measure the angle of tibial external rotation. Intra-class correlation coefficient (ICC) and the standard error of measurement (SEM) values were used to determine the within- and between- day intra-rater test-retest reliability of using DrG and a three dimensional motion analysis system. To assess validity, Pearson correlation coefficients were used for two measurement techniques. The measurement for tibial external rotation had high intra-rater test-retest reliability of within-day (ICC=.88) and between-day (ICC=.83) reliability using DrG and of within-day (ICC=.93) and between-day (ICC=.77) reliability using a three-dimentional motion analysis system. Tibial external rotation angle measurement using DrG was highly correlated with those of the three-dimensional motion analysis system (r=.86). These results represented that the tibial external rotation angle measurement using DrG showed acceptable reliability and validity compared with the use of three-dimensional motion analysis system.

• 시스템엔지니어링학술지
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• 제12권1호
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• pp.105-112
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• 2016

An aircraft must be designed to minimize system failure rate for obtaining the aircraft safety, because the aircraft system failure causes a fatal accident. The safety of the aircraft system can be predicted by analyzing availability, reliability, and maintainability of the system. In this study, the reliability and the maintainability of the hydraulic system are analysed except the availability, and therefore the reliability and the maintainability analysis process and the results are presented for a helicopter hydraulic system. For prediction of the system reliability, the failure rate model presented in MIL-HDBK-217F is used, and MTBF is calculated by using the Part Stress Analysis Prediction and quality/temperature/environmental factors described in NPRD-95 and MIL-HDBK-338B. The maintainability is predicted by FMECA(Failure Mode, Effect & Criticality Analysis) based on MIL-STD-1629A.

• 한국신뢰성학회지:신뢰성응용연구
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• 제16권1호
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• pp.64-70
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• 2016

Purpose: The purpose of this study was to evaluate performance reliability of stroke patients using kinematic analysis. Methods: A protocol to evaluate performance reliability was performed for three tasks on 20 stroke patients and 10 normal people. The tasks include hand to head (HH) task, hand to mouth (HM) task, and hand to target (HT) task. Results: The affected arms showed smaller joint angle, slower peak velocity, longer time to peak velocity for task performances than control group. Also, slower peak velocity and longer movement time for task performance in unaffected arm of stroke patients were obtained compared with the control group. Conclusion: Kinematic analysis is very useful quantitative tool to provide understanding on upper extremity function of stroke patients.

• 한국환경과학회지
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• 제8권5호
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• pp.559-568
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• 1999

This study was conducted to develop the questionnaire for the measurement of environmental attitudes and test its reliability and validity. Development and valiadation of the 46 survey items that measure environmental attitudes were described. The total of 3 surveys were conducted and the total of 510 persons including diverse sample groups were questionnaired. The SAS $PC^+$ package program was used in both the reliability analysis and the validity analysis of surveyed data. Results revealed the very high reliability and the high validity of the questionnaire. The reliability of the finalized questionnaire was increased to the level of Cronbach-$\alpha$ 0.92 after the repeated reliability analyses and revisions of the firstly and secondly designed questionnaires. The validity of our questionnaire was sufficiently affirmed through the use and aplication of factor analysis and known-groups technique.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1914-1917
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• 2005

Recently, the reliability evaluation and analysis are applied for many industrial products, and many products are required to guarantee in quality and in efficiency. The purpose of this paper is to present some of reliability evaluation methodologies that are applicable to machine tools. Especially ATC(Automatic Too Changer), which is core component of line center, was chosen as the target of the reliability evaluation and analysis. The scope of research is reliability prediction, reliability test and evaluates their results. The results of this research has shown the failure rate, MTBF(Mean Time Between Failure), reliability for those components and real tests reliability through constructed reliability test-bed. It is expected that proposed methodologies will increase reliability for high speed line center.

• 한국안전학회지
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• 제32권3호
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• pp.54-59
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• 2017

This paper presents an efficient finite analysis model and a simulation-based reliability analysis method for stowage device system failure of a container crane with respect to lateral load. A quasi-static analysis model is introduced to simulate the nonlinear resistance characteristics and failure of tie-down and stowage pin, which are the main structural stowage devices of a crane. As a reliability analysis method, a subset simulation method is applied considering the uncertainties of later load and mechanical characteristic parameters of stowage devices. An efficient Markov chain Monte Carlo (MCMC) method is applied to sample random variables. Analysis result shows that the proposed model is able to estimate the probability of failure of crane system effectively which cannot be calculated practically by crude Monte Carlo simulation method.