• Title, Summary, Keyword: unreliability

Search Result 62, Processing Time 0.03 seconds

A Study on Reliability Analysis of Substation Automation System (변전소 자동화 시스템의 신뢰도 해석에 관한 연구)

  • Park, Chul-Won
    • The Transactions of the Korean Institute of Electrical Engineers P
    • /
    • v.64 no.4
    • /
    • pp.281-285
    • /
    • 2015
  • Electrical energy supply interruption degrades reliability of power supply as well as social costs and economic loss. It is important to assess the reliability of the power system. Nowadays IEC61850 based substation automation system(SAS) has been developed for an updating of automation and interoperability. In this study, three kinds of reliability block diagram(RBD) were proposed to examine of network availability of the three types SAS. And reliability and unreliability of the SAS was formulated using the RBD. Finally, while varying the value of reliability and unreliability, the reliability and the unreliability of the overall system were evaluated.

A Case Study of the Commom Cause Failure Analysis of Digital Reactor Protection System (디지털 원자로 보호시스템의 공통원인고장 분석에 관한 사례연구)

  • Kong, Myung-Bock;Lee, Sang-Yong
    • IE interfaces
    • /
    • v.25 no.4
    • /
    • pp.382-392
    • /
    • 2012
  • Reactor protection system to keep nuclear safety and operational economy of plants requires high reliability. Such a high reliability of the system can be achieved through the redundant design of components. However, common cause failures of components reduce the benefits of redundant design. Thus, the common cause failure analysis, to accurately calculate the reliability of the reactor protection system, is carried out using alpha-factor model. Analysis results to 24 operating months are that 1) the system reliability satisfies the reliability goal of EPRI-URD and 2) the common cause failure contributes 90% of the system unreliability. The uncertainty analysis using alpha factor parameters of 0.05 and 0.95 quantile values shows significantly large difference in the system unreliability.

A New Initial Value for Solving Redundancy Optimization Problems (중복설계 최적화문제의 새로운 초기 값 설정에 관한 연구)

  • 이도경;이근희
    • Journal of the Society of Korea Industrial and Systems Engineering
    • /
    • v.15 no.25
    • /
    • pp.11-14
    • /
    • 1992
  • This paper presents a method for establishing an initial value of redundancy optimization problem to maximize system reliability of multiconstraint mixed parallel-series system. The constraints not be linear. This paper proposes a new initial value which is near to optimal solution by considering the relative median rate of the unreliability and amount of consumed resources for each subsystem. To show the efficiency of this model. numerical example and comparison with Narasimhalu is illustrated in chapter 4.

  • PDF

A Study on Cost Function of Korea Railroad Industry( I ) (우리나라 철도산업의 비용함수추정 연구(I))

  • Yoo Jae-Kyun;Kim Kyoung-Tae
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.392-396
    • /
    • 2004
  • The number of parameters and the number of samples are the key point of trans-log cost function which studied recently. Most of models show that the number of parameters is more than the number of samples. Therefore, these studies gave unreliability of the estimation results. First, we surveyed theoretical cases and researches for the formulation of cost function of railroad industry. Second, we will suggest trans-log cost function by analyzing cost data of KNR. And, the cumulative data will be needed for the confidence of estimation results.

  • PDF

A Study on Cost Function of Korea Railroad Industry(I) (우리나라 철도산업의 비용함수추정 연구(I))

  • Yoo Jae-Kyun;Kim Kyoung-Tae
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.1765-1769
    • /
    • 2004
  • The number of parameters and the number of samples are the key point of trans-log cost function which studied recently. Most of models show that the number of parameters is more than the number of samples. Therefore, these studies gave unreliability of the estimation results. First, we surveyed theoretical cases and researches for the formulation of cost function of railroad industry. Second, we will suggest trans-log cost function by analyzing cost data of KNR. And, the cumulative data will be needed for the confidence of estimation results.

  • PDF

Recent Development of Automated Strain Measurement System for Sheet Metal Parts (판재 변형률 자동측정시스템의 발전)

  • 김형종
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • /
    • pp.129-133
    • /
    • 2000
  • It is reasonable to use the stereo vision and image processing technique to digitize 3D coordinates of grid points and to evaluate surface strains on a sheet metal parts. However this method has its intrinsic problems such as the difficulty in enhancement of bad images inevitable error due to digital image resolution of camera and frame grabber unreliability of strains and thickness evaluated from coarse grid on the corner area with large curvature and the limitation of the area that can be measured at a time. Therefore it is still hard to measure strain distribution over the entire surface of a medium,- or large-sized stamped part at a time even by using an automated strain measurement system. In this study the curvature correction algorithm based on the grid refinement and the geometry assembling algorithm based on the global error minimization (GEM) scheme are suggested. Several applications are presented to show the reliability and efficiency of these algorithms.

  • PDF

Multiple Description Coding using Whitening Transform (Whitening Transform을 이용한 Multiple Description Coding)

  • 최광표;이근영
    • Proceedings of the IEEK Conference
    • /
    • /
    • pp.41-44
    • /
    • 2002
  • In the communications systems with diversity, we are commonly faced on needing of new source coding technique, error resilient coding. The error resilient coding addresses the coding algorithm that has the robustness to unreliability of communications channel. In recent years, many error resilient coding techniques were proposed such as data partitioning, resynchronization, error detection, concealment, reference picture selection and multiple description coding (MDC). In this paper, we proposed an MDC using whitening transform. The conventional MDC using correlating transform is need additional information to decode the image. But, if an image is transformed using the whitening transform, the additional information is not necessary to transform because the coefficients of whitening transform have uni-variance statistics.

  • PDF

Operation peration and Management of Irrigation System-Concept and Technology (관개조직의 유지관리)

  • Kuroda, Masaharu
    • Proceedings of the Korean Society of Agricultural Engineers Conference
    • /
    • /
    • pp.1-7
    • /
    • 1999
  • The control system is very important for the precise operation and suitable management of irrigation system. The Japanese Society of Irrigation, Drainage and Reclamation Engineering has a committee for investigating irrigation system control. The committee is trying to set up a manual for the control system. The concept of the control system in the preparing manual will be discussed in this report.

  • PDF

DETERMINATION OF UNRELIABILITY BOUNDS IN DESIGN BY STRESS AND STRENGTH INTERFERENCE

  • Oh, Chung Hwan
    • Journal of the Society of Korea Industrial and Systems Engineering
    • /
    • v.12 no.20
    • /
    • pp.25-32
    • /
    • 1989
  • 열화수신포에 있어서 확률론적 신뢰도설계 및 단순스트레스와 강도의 고장모형은 렌덤 수치들로 구성된 각 분포의 간섭(Interference) 확률에 의해 이루어진다. 현재까지 이러한 분포모형들의 신경도는 분석적, 수치적 또는 모의실험방법론학에 의해서 단일추정치를 계산및 해석하여 왔으나 현실적으로는 스트레스 강도함수 분포의 간섭구간에 있어서 그 렌덤 변수들에 대한 완전한 실제의 분포들을 파악하기란 너무 복잡하고 때로는 불가능하다. 이를 위해서는 신뢰도의 상·하한 결정으로 신뢰도설계를 하는 방법이 고려된다. 본 연구에서는 스트레스와 강도의 렌덤 변수들에 대한 중복부분(Overlapping tails) 내에 있어서 각각의 주어진 구간확률을 제약조건으로 하여 최적신뢰도 한계를 결정 및 설계하는 새로운 기법을 제시한다. 설계신뢰도의 최적상한 및 하한 값은 제공하기 위하여 비선형모형인 Quadratic programming optimization 기법을 이용하여 신뢰도분석관점에 입각한 특수구조모형을 설정하고 이에 대한 수치예를 들어 예증하였다.

  • PDF

A new proposal for the appropriate quality control of driven piles by using set values (최종관입량을 기준으로 한 합리적인 말뚝 시공관리 방안)

  • 이명환;홍헌성;김성회;전영석
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • /
    • pp.51-63
    • /
    • 2000
  • Because of simplicity and easiness, dynamic pile driving formulae have long been used by most of the field engineers for pile quality control purposes. Yet their reliability have been repeatedly reported unsuitable and the results can lead to significant errors. According to the research results by the authors, the two most important sources of unreliability of dynamic pile driving formulae are uncertainty in the estimation of hammer efficiency and time dependent characteristics of pile bearing capacity. Based on this finding a new method is proposed. By using the actual value of hammer efficiency the pile bearing capacity at the time of driving could be reasonably estimated. By performing restrike test sometime after pile installation, time effect coefficient could be determined. The effectiveness of the proposed method was proven in the actual construction project.

  • PDF