• Journal of Electrical Engineering and Technology
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• 제2권4호
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• pp.441-444
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• 2007

The mechanical endurance is the critical characteristic of Magnetic contactors (MCs), which are widely used in such industrial equipments as elevators, cranes, and factory control rooms in order to close and open the control circuit. Testing time, however, is so long in most cases that some method of reducing the testing period is required. Therefore, the degradation test by the detected vibration of MCs is developed to reduce the testing time in this work. The degradation test data are analyzed and the prediction model is provided. Also, the possibility of this technology for Reliability Centered Maintenance (RCM) will be shown. This will reduce the period of the product development and raise the reliability of the equipment in power distribution.

• 한국정밀공학회지
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• 제20권11호
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• pp.127-133
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• 2003

Pin-on-disk and hardness tests using mechanical components of M-20J aircraft braking system were performed to identify the friction and wear characteristics. The intention of this work was also to analyze a 5-year term maintenance record of an M-20J aircraft. used for flight training at Hankook Aviation University, and to determine the reliability of the brake system of an M-20J aircraft. The mean wear coefficients of the lining sliding against the brake disk were compared between the test and reliability estimation to obtain a predictive wear model.

• Nuclear Engineering and Technology
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• 제52권8호
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• pp.1697-1705
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• 2020

To enhance the credibility of human reliability analysis, various kinds of data have been recently collected and analyzed. Although it is obvious that the quality of data is critical, the practices or considerations for securing data quality have not been sufficiently discussed. In this work, based on the experience of the recent human reliability data extraction projects, which produced more than fifty thousand data-points, we derive a number of issues to be considered for generating meaningful data. As a result, thirteen considerations are presented here as pertaining to the four different data extraction activities: preparation, collection, analysis, and application. Although the lessons were acquired from a single kind of data collection framework, it is believed that these results will guide researchers to consider important issues in the process of extracting data.

• ETRI Journal
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• 제14권4호
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• pp.19-27
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• 1992

Since. as is well known, direct computation of the reliability for a large-scaled and complex net work generally requires exponential time, a variety of alternative methods to estimate the network reliability using simulation have been proposed. Monte Carlo sampling is the major approach to estimate the network reliability using simulation. In the paper, a dynamic Monte Carlo sampling method, called conditional minimal cut set (CMCS) algorithm, is suggested. The CMCS algorithm simulates a minimal cut set composed of arcs originated from the (conditional) source node until s-t connectedness is confirmed, then reduces the network on the basis of the states of simulated arcs. We develop the importance sampling estimator and the total hazard estimator and compare the performance of these simulation estimators. It is found that the CMCS algorithm is useful in reducing variance of network reliability estimator.

• Advances in concrete construction
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• 제9권2호
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• pp.149-159
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• 2020

The present work proposes new engineering models for determining corrosion initiation time in concrete reinforcing steels in marine environment. The models are based on Fick's second law that is commonly used for chloride diffusion. The latter is based on deterministic analyses involving the most influencing parameters such as distance of the concrete structure from the seaside, depth of steel concrete cover, ambient temperature, relative humidity and the water-cement ratio. However, a realistic corrosion initiation time cannot be estimated because of the uncertainties associated to the different parameters of the models. Therefore a reliability approach using FORM/SORM method has been applied to develop the proposed engineering models integrating a limit state function and a reliability index β. As a result, the corrosion initiation time is expressed by new exponential engineering models where the uncertainties are associated to the model parameters. The main emerging result is a realistic decision tool for corrosion planning inspection.

• International Journal of Reliability and Applications
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• 제7권2호
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• pp.141-153
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• 2006

In this paper, we present the U-Statistic test for testing exponentiality against new renewal better than used (NRBU) based on a goodness of fit approach. Selected critical values are tabulated for sample sizes n=5(1)30(10)50. The asymptotic Pitman relative efficiency relative to (NRBU) test given in the work of Mahmoud et all (2003) is studied. The power estimates of this test for some commonly used life distributions in reliability are also calculated. Some of real examples are given to elucidate the use of the proposed test statistic in the reliability analysis. The problem in case of right censored data is also handled.

• 한국구조물진단유지관리공학회 논문집
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• 제5권4호
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• pp.177-184
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• 2001

In this study, three most distinct types of general rigid connections are included in the modelling, with is implemented into a computer code. The cost, functions of connections are constructed by using the estimated unit cost of bolting, welding and connection-steel elements incorporating all the effect of materials, labor, and fabrication work. Bused on the recent developments of the reliability-based structural analysis and design as well as the extending knowledge on the probabilistic characteristics of load and resistances, the probability based design criteria have been successfully developed for many standards. Since the probabilistic characteristics depend highly on the local load and resistances, it is recognized to develop the design criterion compatible with domestic requirements. The existing optimum design methods, which are generally based on the structural theory and certain engineering experience, do not realistically consider the uncertainties of load and resistances and the basic reliability concepts.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2001년도 학술대회지
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• pp.422-427
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• 2001

건설프로젝트에서 현재 사용되고 있는 작업분류체계(Work Breakdown Structure)는 프로세스 내의 세부작업간 선·후행 관계의 불확실성과 작업의 불합리한 상호 연계성에 기인한 문제점을 내포하고 있다. 이를 해결하기 위해서 본 논문에서는 Work Structuring을 제시하여 프로세스간에 투명성을 부여하고 세부작업간의 간섭을 제거시켜 작업신뢰성을 향상할 수 있는 방안을 도출하였고 프로세스를 개선하기 위한 프로세스 디자인 다이어그램을 개발하였다. WS에 의한 프로세스 개선의 목적은 고객에게 가치를 창출시켜주면서 보다 신속하고 신뢰성 있는 작업 흐름을 만드는 것을 목적으로 하고 있으며 비가치 창출작업의 감소, 프로세스의 명료화 및 투명성 향상 등에 의의가 있다.

• 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.

• 품질경영학회지
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• 제19권1호
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• pp.43-50
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• 1991

Very little work has been done in the design of process with purchased equipment; therefore it is the intent of this project to expand the current application of reliability considerations to purchased equipment. The procurement of equipment in a manufacturing system which has both qualitative and quantitative aspects.