• 한국철도학회논문집
• /
• 제20권5호
• /
• pp.569-576
• /
• 2017

전동차의 공기 작동식 출입문을 작동하기 위한 공기를 공급 또는 차단의 역할을 하는 전자변은 고장발생시 승객의 안전은 물론 정상운행을 불가능하게 하는 중요한 부품이므로 높은 신뢰도가 요구되지만 누기로 인한 고장 비율이 높은 편이다. 국내 도시철도 운영기관들은 고정주기와 임의 여유기간을 적용한 전동차 중정비 주기로 전자변을 정비한다. 현행 중정비 주기 방식의 대안으로 고장 신뢰도를 고려한 정비주기를 제시하고자 지하철 6호선 전동차 전자변 고장 통계자료에 상용 통계프로그램(MINITAB)을 적용하여 신뢰도 함수(Reliability Function)와 임무신뢰도(Mission Reliability)를 계산하고 적정 정비주기를 도출하였다. 도출된 정비 주기는 현 4년 주기의 정비의 부품신뢰도를 68%에서 95%로 향상시키는 것이므로 전자변의 신뢰도를 획기적으로 향상시킬 수 있을 것이다.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제17권1호
• /
• pp.28-37
• /
• 2017

Purpose: This paper proposes a procedure that may infer and identify interaction failures in a module. Methods: In design FMEA, we defined an interaction model between components and proposed a method for selecting a single component by using the standard specification classification table and four methods for choosing the related components. We also introduced the function tree for function and requirement characteristic analysis and proposed utilization of standard stress lists and 1st and 2nd stress analysis tables to determine the effect the stress analysis has on interactions. Finally, the interaction mechanism diagram was proposed and used to infer the failure mechanism. Process FMEA also established procedures in a similar way. Results: We established a procedure for predicting the failure mode due to interaction between components based on Company A's multi-step FMEA procedure. Conclusion: By applying the proposed interaction FMEA procedure to the development model, we were able to confirm the effect of the new derivation on the failure mode of interaction, which was not predicted by the existing FMEA.

• 산경연구논집
• /
• 제9권12호
• /
• pp.63-72
• /
• 2018

Purpose - In this study, it is classified the service quality dimension of mobile shopping app using Kano model. In addition, it is evaluated quality factors suitable for strategic management from the viewpoint of service provider through mobile application through binary dimension analysis. Research design, data, and methodology - In this study, seven quality dimensions such as information quality, reliability, immediacy, convenience, design, security and customer service were derived through related studies to make binary shopping quality app quality measurement. 37 sub-variables were set by each quality dimensions. Each questionnaire was composed of positive and negative items like Kano's proposed method, and the satisfaction coefficient suggested by Timko(1993) was examined to understand the influence of each factors on customer satisfaction. Results - As a result of research, shopping app users perceived unity quality factor in most items of service quality dimension such as information quality, reliability, immediacy, convenience and customer service. In addition, the satisfaction coefficient showed a good impression, quick response of the result, fast delivery, and the unsatisfactory coefficient showed more interest in personal information such as payment method safety, and transaction security. As a result of research, shopping app users perceived unity quality factor in most items of service quality dimension such as information quality, reliability, immediacy, convenience and customer service. And, in information quality, the information overload was classified as an apathetic quality component, while the related information provision belonged to an attractive quality component. In reliability quality, customized service provision was classified as an attractive quality component. In instant connectivity, the quality of the connection during transport was classified as an attractive quality component. In convenience quality, access to product information was classified as a one-way quality component. All components of designs quality were classified as attractive quality components, and in security quality, all of their components were all classified as one quality component. Lastly, in customer service, they components were all classified as a single quality component. In addition, the satisfaction coefficient showed a good impression, quick response of the result, fast delivery, and the unsatisfactory coefficient showed more interest in personal information such as payment method safety, and transaction security. Conclusion - In the online service environment, which is difficult to differentiate in terms of upward upgrading only by technological implementation and function, the results of this study can be suggested as a differentiating factor for major channels with customers rather than improve the brand image.

• Structural Engineering and Mechanics
• /
• 제65권6호
• /
• pp.751-760
• /
• 2018

Damages in concrete structures due to aging and other factors could be a serious and immense matter. Making the best selection of the most viable and practical repairing and strengthening techniques are relatively difficult tasks using traditional methods of structural analyses. This is due to the fact that the traditional methods used for assessing aging structure are not fully capable when considering the randomness in strength, loads and cost. This paper presents a reliability-based methodology for assessing reinforced concrete members. The methodology of this study is based on probabilistic analysis, using statistics of the random variables in the performance function equations. Principles of reliability updating are used in the assessment process, as new information is taken into account and combined with prior probabilistic models. The methodology can result in a reliability index ${\beta}$ that can be used to assess the structural component by comparing its value with a standard value. In addition, these methods result in partial safety factor values that can be used for the purpose of strengthening the R/C elements of the existing structure. Calculations and computations of the reliability indices and the partial safety factors values are conducted using the First-order Reliability Method and Monte Carlo simulation.

• Earthquakes and Structures
• /
• 제11권4호
• /
• pp.701-721
• /
• 2016

Base isolation is a well-established passive strategy for seismic response control of buildings. In this paper, an efficient framework is proposed for reliability-based design optimization (RBDO) of isolated buildings subjected to uncertain earthquakes. The framework uses reduced function evaluations method, as an efficient tool for structural reliability analysis, and an efficient optimization algorithm for optimal structural design. The probability of failure is calculated considering excessive base displacement, superstructure inter-storey drifts, member stress ratios and absolute accelerations of floors of the isolated building as failure events. The behavior of rubber bearing isolators is modeled using nonlinear hysteretic model and the variability of future earthquakes is modeled by applying a probabilistic approach. The effects of pulse component of stochastic near-fault ground motions, fixity-factor of semi-rigid beam-to-column connections, values of isolator parameters, earthquake magnitude and epicentral distance on the performance and safety of semi-rigidly connected base-isolated steel framed buildings are studied. Suitable RBDO examples are solved to illustrate the results of investigations.

• 한국가스학회지
• /
• 제16권4호
• /
• pp.8-15
• /
• 2012

GO-FLOW기법은 시스템이 정상적으로 작동할 가능성을 평가할 수 있는 기법으로써 신호선과 연산자를 사용하여 시스템을 GO-FLOW Chart로 모델화하고, 이 GO-FLOW Chart를 순차적으로 해석하여 시스템의 신뢰도를 평가하는 기법이다. 그러나 GO-FLOW기법은 1개의 시스템 구성요소를 여러 개의 연산자로 모델링하므로 시스템 흐름도와 상이한 GO-FLOW Chart가 작성될 수 있고, 시간점을 지정하여 시간을 모델링하므로 실제 운전시간에 따른 신뢰도 변화를 평가하기 어렵다. 따라서 본 연구에서는 구성요소의 기능(정상/고장)을 기준으로 시스템의 신뢰도를 평가하는 기법을 개발하였다. 본 기법은 구성요소의 운전상태와 상관없이 그 기능을 유지할 가능성을 기준으로 시스템의 신뢰도를 평가하며, 1개의 구성요소는 1개의 연산자로 모델링하므로 시스템 흐름도와 거의 유사한 모델도를 작성할 수 있고, 실제시간을 반영한 연산자를 사용하여 실제시간에 따른 시스템의 신뢰도를 쉽게 평가할 수 있다.

• 한국군사과학기술학회지
• /
• 제21권5호
• /
• pp.697-703
• /
• 2018

In this paper, we analyzed the operation of the ignition circuit for electronic arm and fire device(EAFD), and investigated the sensitive elements of the circuit system. For reliability analysis, the EAFD ignition circuit was modeled using the PSpice simulation tool, and the output results of the circuit were examined by changing the tolerance of each circuit element. Monte Carlo simulation was used by maintaining the values of the observed sensitive elements at ${\pm}10%$ of the original values and adjusting the values of the other components according to a random distribution. The histogram results of the output peak currents and pulse widths were represented by Weibull and Burr type XII function fittings in three cases(element values are +10 %, 0 %, -10 % of original). For the output peak currents, mean values were 1.0028, 1.0034, and 1.0050, where the variance values were calculated as 0.0398, 0.0396, and 0.0290 using the Weibull function fitting, respectively. For pulse widths, the mean values of 0.9475, 0.9907, and 1.0293 with the variance values of 0.0260, 0.0251, and 0.0238 were obtained using the Burr Type XII function fittings.

• 한국통신학회논문지
• /
• 제17권6호
• /
• pp.595-603
• /
• 1992

통신망의 신뢰도 계정을 하는데 있어서 대형망에서는 소자(component)들의 증가로 인한 계산상 어려움과 복잡성 때문에 NP,hard 문제가 발생한다. 이러한 문제점을 해결하기 위하여 본 논문에서는 통신망의 시점(source node)과 종점 (terminal node)간에 상한고 하한 근사 신뢰도를 구하는 알고리즘을 제시하였다. 계정 절차는 우선, 최소 경로 집합(minimal pathset)과 최소 컷셋(minimal cutest)을 구한다. 그 다음, 소자의 수가 동일한 사상(pathset, cutest)끼리 분리한 후 공통변수(common variable)를 추출한 부분함수를 구하여 근사 신뢰도를 계정하였다. 또한 본 논문에서 제시한 알고리즘의 성능을 평가하기 위하여 Esary-Proschan, Shogan과 Gopal의 대칭망 알고리즘고 비교 하였다.

• Journal of Power Electronics
• /
• 제3권3호
• /
• pp.145-150
• /
• 2003

Reliability, availability, and cost have been the major concerns for photovoltaic hybrid systems since their beginning as primary sources for much critical applications like communication units and repeaters. This paper descnbes the performance of two hybrid systems, photovoltaic-battery, wind-turbine coupled with the public-grid (PVBWG) hybrid system and photovoltaic-battery, wind-turbine coupled With the diesel generator (PVBWD) hybrid system The systems are sized to power a typical 300W/48V de telecommunication load continuously throughout the year Such hybrid systems consist of subsystems, which in turn consist of components Failure of anyone of these components may cause failure of the entire system. The reliability and availability basics, and estimation procedure for the two proposals are introduced also in this paper. The PVBWG and PVBWD system configurations are shown with the relevant mean-time-between-faIlure (MTBF) and failure rate (${\lambda}$) of each component. The characteristics equations of the two systems are deduced as a function of operating hours and the percentage of sun and wind availabilities per day. The system probability failure as well as the reliability is estimated based on the fault tree analysis technique. The results show that, by using standard or normal components MTBF, the PVBWG is more reliable and the time of periodic maintenance period is more than one year especially in the rich sites of both sun and wind, but PVBWD competes else Also, in the first five years from the system installation, the system is quit reliable and may not require any maintenance. The results show also, as the sun and wind are available, as the system reliable and available.

• 한국멀티미디어학회논문지
• /
• 제7권10호
• /
• pp.1496-1504
• /
• 2004

웹 서비스는 인터넷을 통해 기업 상호간에 비즈니스를 연결할 수 있도록 하는 것으로, 서비스 구축의 비용 감소와 속도 증진이 가능하다. 또한, 다른 영역과의 통합이 쉽게 가능하며, 컴포넌트 기반으로 개발할 경우 업데이트나 수정이 재사용성과 대체성을 제공함으로써 용이하다. 본 논문에서는 서비스지향 아키텍처 상에서 공급자 측면에서 구현되는 웹 서비스를 신뢰성과 민첩성을 보장하기 위해 컴포넌트 기반으로 개발하고자 한다. 이를 위해서 구성되는 컴포넌트를 효율적으로 통합하기 위한 아키텍처를 제안하고, 개발 프로세스를 서술한다. 또한, 컴포넌트를 기반으로 웹 서비스를 개발하기 위해 웹 서비스의 구조를 논리적으로 계층화하여 각 계층에서의 기능을 정의하였으며, 논리적 계층을 기반으로 아키텍처를 제시한다. 이들 내부는 크게 Facade와 Backside 컴포넌트로 구성하며, 웹 서비스 기능을 가지고 있는 Facade 컴포넌트를 개발하기 위한 프로세스와 메일링 웹 서비스를 사례로 제시한다. 이를 통해 웹 서비스의 생산비용과 개발시간의 절감을 기대할 수 있으며, 컴포넌트를 기반으로 웹 서비스를 구성하여 재사용성과 대체성에 대한 신뢰성 향상을 가져온다.