• 한국산업정보학회논문지
• /
• 제8권4호
• /
• pp.94-100
• /
• 2003

본 논문에서는k개 성분들이 지수분포를 따르는 병렬시스템에서 하나의 성분이 고장났을 때 나머지성분들의 수명분포에 영향을 줄 때 주어진 시각 t 에서 시스템의 신뢰도, 위험함수, 평균잔여수명, 신뢰도에 대한 최우추정량과 최소분산불편추정량을 제시하고 그리고 모의실험을 통하여 추정량들의 효율성을 연구한다.

• Geomechanics and Engineering
• /
• 제29권3호
• /
• pp.331-338
• /
• 2022

Face stability analyses provides the most probable failure mechanisms and the understanding about parameters that need to be considered for the evaluation of ground movements caused by tunneling. After the Upper Bound Method (UBM) solution which can consider the influence of seepage forces and depth-dependent effective cohesion is verified with the numerical experiments, the probabilistic model is proposed to calculate the unbiased limiting tunnel collapse pressure. A reliability analysis of a shallow circular tunnel driven by a pressurized shield in a frictional and cohesive soil is presented to consider the inherent uncertainty in the input parameters and the proposed model. The probability of failure that exceeding a specified applied pressure at the tunnel face is estimated. Sensitivity and importance measures are computed to identify the key parameters and random variables in the model.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 A
• /
• pp.46-49
• /
• 2003

This paper proposes a method to solve expansion problem for a transmission network, given future generation and load strategy, and alternative types of lines available, subject to load, reliability and right of way constraints, the problem is formulated as a series of zero one integer programs which are solved by an efficient branch and bound algorithm A study test result on the 63-buses test system shows that the proposed method is practical and efficiently applicable to the transmission expansion planning.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제14권1호
• /
• pp.71-80
• /
• 2014

In the mechanical design process various types of errors are bound to occur. In order to prevent such mechanical malfunctions and decrease number of instances of errors, various technique are utilized. The purpose of this research is to demonstrate the effectiveness of the combined service Blueprint and FMEA (Failure Mode and Effect Analysis) by applying such method to machine process. The results are as follows: First, modification can be obtained by discovering the failure mode hidden within the inner side of the blueprint. Second, issues within the company are found when conducting the machine design process that is not visible from the outside. Therefore, potential errors can be effectively resolved by preventing failure mode in advance and eventually high quality of the product could be obtained as well as its reliability.

• 한국신뢰성학회:학술대회논문집
• /
• 한국신뢰성학회 2004년도 정기학술대회
• /
• pp.303-311
• /
• 2004

This paper presents the reliability estimation of door hinge for home appliances, which consists of bushing and shaft. The predominant failure mechanism of bushing made of polyoxymethylene(POM) is brittle fracture due to decrease of strength caused by voids existing, and that of shaft made of acrylonitrile-butadiene-styrene(ABS) is creep due to plastic deformation caused by excessive temperature and lowering of glass transition temperature by absorbed moisture. Since the brittle fracture of bushing is overstress failure mechanism, the load-strength interference model is used to estimate the failure rate of it along with failure analysis. By the way, the creep of shaft is wearout failure mechanism, and an accelerated life test is then planned and implemented to estimate its lifetime. Through the technical review about failure mechanism, temperature and humidity are selected as accelerating variables. Assuming Weibull lifetime distribution and Eyring model, the life-stress relationship and acceleration factor, B$_{10}$ life and its lower bound with 90% confidence at worst case use condition are estimated by analyzing the accelerated life test data.a.

• 한국전산구조공학회논문집
• /
• 제21권3호
• /
• pp.275-280
• /
• 2008

신뢰성 기반 형상 최적화(RBDO)글 위한 기술은 한정된 정보로 인한 인식론적 불확실성을 다룰 수 있는 베이지안 접근에 근거하여 발달된다. 최근까지, 전통적인 RBDO는 측정 데이터가 무한히 많아서 확실한 확률정보를 알고 있다는 가정 하에 실행되었다. 하지만 실제로는, 부족한 데이터로 인해 기존의 RBDO 방법의 유용성을 떨어뜨린다. 본 연구에서는, 확률정보의 불확실성을 인식하고, 따라서 산포를 갖게 되는 시스템 신뢰도의 확률 분포에서의 신뢰수준의 하한 값을 고려하기 위해 '베이지안 신뢰성'이 소개된다. 이런 경우, 베이지안 신뢰성 해석은 기존 신뢰도 해석의 이중 해석을 요구하게 된다. 크리깅 기반 차원 감소 방법(KDRM)은 신뢰도 해석을 위한 새로운 효율적인 방법으로써 사용되며, 제시된 방법은 몇 가지 수치예제를 사용하여 설명된다.

• 한국국방경영분석학회지
• /
• 제11권2호
• /
• pp.53-63
• /
• 1985

This paper presents a multi-costraint optimization model for redundant system reliability. The optimization model is usually formulated as a nonlinear integer programming (NIP) problem. This paper reformulates the NIP problem into a linear integer programming (LIP) problem. Then an efficient 'Branch and Straddle' algorithm is proposed to solve the LIP problem. The efficiency of this algorithm stems from the simultaneous handling of multiple variables, unlike in ordinary branch and bound algorithms. A numerical example is given to illustrate this algorithm.

• 품질경영학회지
• /
• 제24권1호
• /
• pp.87-95
• /
• 1996

We construct bootstrap confidence bounds for reliability, R=P(X>Y), where X and Y are independent normal random variables. 1-way random effect models with equal variances are assumed for the populations of X and Y. We compare the accuracy of the proposed bootstrap confidence bounds and classical confidence bound for small samples via Monte Carlo simulation.

• Structural Engineering and Mechanics
• /
• 제62권4호
• /
• pp.507-517
• /
• 2017

Due to the discontinuous nature of uncertainty quantification in conventional evidence theory(ET), the computational cost of reliability analysis based on ET model is very high. A novel ET model based on fuzzy distribution and the corresponding combination rule to synthesize the judgments of experts are put forward in this paper. The intersection and union of membership functions are defined as belief and plausible membership function respectively, and the Murfhy's average combination rule is adopted to combine the basic probability assignment for focal elements. Then the combined membership functions are transformed to the equivalent probability density function by a normalizing factor. Finally, a reliability analysis procedure for structures with the mixture of epistemic and aleatory uncertainties is presented, in which the equivalent normalization method is adopted to solve the upper and lower bound of reliability. The effectiveness of the procedure is demonstrated by a numerical example and an engineering example. The results also show that the reliability interval calculated by the suggested method is almost identical to that solved by conventional method. Moreover, the results indicate that the computational cost of the suggested procedure is much less than that of conventional method. The suggested ET model provides a new way to flexibly represent epistemic uncertainty, and provides an efficiency method to estimate the reliability of structures with the mixture of epistemic and aleatory uncertainties.

• Journal of Communications and Networks
• /
• 제11권4호
• /
• pp.390-405
• /
• 2009

Wireless sensor networks (WSNs) are envisioned to facilitate information gathering for various applications and depending on the application types they may require certain quality of service (QoS) guarantee for successful and guaranteed event perception. Therefore, QoS in WSNs is an important issue and two most important parameters that hinder the goal of guaranteed event perception are time-sensitive and reliable delivery of gathered information, while a minimum energy consumption is desired. In this paper, we propose an energy-aware, multi-constrained and multipath QoS provisioning mechanism for WSNs based on optimization approach. Hence, a detailed analytical analysis of reliability, delay and energy consumption is presented to formulate the optimization problem in an analytical way. A greedy algorithm is proposed to achieve the desired QoS guarantee while keeping the energy consumption minimum. Also, a simple but efficient retransmission mechanism is proposed to enhance the reliability further, while keeping the delay within delay bound. Simulation results demonstrate the effectiveness of our scheme.