• 한국신뢰성학회지:신뢰성응용연구
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• 제5권1호
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• pp.149-165
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• 2005

Air spring system was accepted for railway vehicle secondary suspension to reduce and absorb the vibration and noise. The low natural frequency ensures a comfortable ride and an invariably good stiffness. In this paper, the characteristics and durability test was conducted in laboratory by using servo-hydraulic fatigue testing system to reliability evaluation of air spring for electric railway vehicle. The experimental results show that the characteristics and durability of domestic development productions are obtained the good results. And to guarantee the adaption of air spring, the ride comfort and air pressure variation were measured in train test on subway line.

• 전기학회논문지
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• 제58권2호
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• pp.308-313
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• 2009

This paper presents a reliability analysis of S-bonds for AF track circuits, which detect train movement and transmit a speed control signal to the train. Field survey shows that S-bonds are exposed to very large vibrations transferred from rail, and suffer from frequent failures when they were installed on ballasted track. We collected the time-to-failure data of S-bonds from the maintenance field of Seoul metro line 2, and made a parametric approach to estimate the statistical distribution that fits the time-to-failure data. The analysis shows that S-bonds have time-to-failure characteristics described by Weibull distribution. The estimated shape parameter of Weibull distribution is 1.1, which means the distribution has constant failure rate characteristics like exponential distribution. The reliability function, hazard function, percentiles and mean lifetime are derived for maintenance support.

• 전기학회논문지
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• 제57권12호
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• pp.2179-2185
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• 2008

This paper deals with the optimal investment method for distribution facilities, based on the analytical approach for the reliability assessment in distribution systems interconnected with new dispersed generations. The existing approach can estimate the expected reliability performance of distribution systems by a direct assessment of the configuration of the systems using the reliability indexes such as NDP(Non-Delivery Power) and NDE(Non-Delivery Energy). The indexes can only consider the number and configuration of the load, but can not consider the characteristics of the load which is the one of the most important factor in the investment cost for the distribution systems. Therefore, this paper presents the new performance indexes for the investment of the distribution facilities considering both the expected interruption cost for the load section and the operation characteristics of dispersed generations. The results from a case study show that the proposed methods can be a practical tool for the voltage management in distribution systems including dispersed sources.

• 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.

• 한국구조물진단유지관리공학회 논문집
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• 제1권1호
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• pp.113-124
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• 1997

Based 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 exprience, do not realistically consider the uncertainties of load and resistances and the basic reliability concepts. This study is directed to propose a optimum design based Expected Total Cost Minimization on two-way slab system which could possibly replace optimum design based traditional provisions of the current code, based on the AFOSM reliablity theory.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2008년도 춘계학술발표논문집
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• pp.87-90
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• 2008

This paper deals with the analytical approach for the reliability assessment in radially operated distribution systems. The approach can estimate the expected reliability performance of distribution systems by a direct assessment of the configuration of the systems using the reliability indexes such as NDP(Non-Delivery Power) and NDE(Non-Delivery Energy). The indexes can consider the number and configuration of the load, but can not consider the characteristics of the load which is the one of the most important factor in the investment cost for the distribution systems. Therefore, This paper presents the new indexes considering the expected interruption cost for the load section and shows the effectiveness by simulating at the model systems.

• Structural Engineering and Mechanics
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• 제62권2호
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• pp.125-138
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• 2017

Reliability-based design optimization (RBDO) is a powerful tool for design optimization when considering probabilistic characteristics of design variables. However, it is often computationally intensive because of the coupling of reliability analysis and cost minimization. In this study, the concept of reliability mapping function is defined based on the relationship between the reliability index obtained by using the mean value first order reliability method and the failure probability obtained by using an improved response surface method. Double-loop involved in the classical RBDO can be converted into single-loop by using the reliability mapping function. Since the computational effort of the mean value first order reliability method is minimal, RBDO by using reliability mapping functions should be highly efficient. Engineering examples are given to demonstrate the efficiency and accuracy of the proposed method. Numerical results indicated that the proposed method has the similar accuracy as Monte Carlo simulation, and it can obviously reduce the computational effort.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2001년도 정기학술대회
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• pp.267-268
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• 2001

We consider some guidance on specifying required dependability characteristics in product and equipment specifications, together with specifications of procedures and criteria for verification.

• 문화기술의 융합
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• 제4권2호
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• pp.115-122
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• 2018

본 연구는 대학생을 대상으로 스마트폰을 이용한 관광정보서비스 특성과 관광정보 신뢰성에 미치는 영향을 파악하기 위하여 실시하였다. 연구대상자는 전라남도와 광주광역시 소재 대학교에 재학 중인 대학생 251명이다. 자료수집은 2017년 10월 23일부터 10월 27일까지 5일간 전남소재 4년재 대학교 2곳과 광주광역시 소재 4년재 대학교 5곳의 캠퍼스를 방문하여 조사하였다. 연구결과, 주로 이용하는 관광정보서비스의 항목에서는 전반적으로 남성보다는 여성들이 항목별 대부분의 서비스를 훨씬 많이 이용하고 있음을 알 수 있다. 또한 남성은 스마트폰 관광정보서비스특성 중 정보적품질 요인이 관광정보 신뢰성에 유의적인 정(+)의 영향을 미치고, 여성은 스마트폰 관광정보서비스특성 중 용이성 요인이 관광정보 신뢰성에 유의적인 정(+)의 영향을 미치는 것으로 나타났다.

• 산경연구논집
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• 제10권8호
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• pp.7-15
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• 2019

Purpose - This study aims to examine the influence of social network service (SNS) on the brand image of infant food products; highlight the effects of brand image on the purchasing and word-of-mouth intention; and explore the effects of the purchasing intention on the word-of-mouth intention. Research design, data, and methodology - Based on previous studies, it was found that the fundamental SNS characteristics for infant food products are reliability, interactivity, and informative. Using AMOS 22.0 and structural equation modeling (SEM), 288 questionnaires were surveyed as a statistical method for examining the proposed hypotheses. Results - The analysis shows that reliability and informative have significant impacts on brand image, whereas interactivity does not. Again, the effect of brand image of infant food products on the purchase and word-of-mouth intention is statistically significant. However, the results differ across the "working housewife" and the "full-time housewife" groups. The connection between reliability and brand image was found to be statistically significant in this study. Conclusions - This study analyzes the effects of SNS characteristics on the brand image of infant food products and the effect of the brand image on purchase and word-of-mouth intentions, and provides practical implications for the same.