• Title, Summary, Keyword: unreliability

Search Result 62, Processing Time 0.034 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

Shunt Active Filter for Multi-Level Inverters Using DDSRF with State Delay Controller

  • Rajesh, C.R.;Umayal, S.P.
    • Journal of Power Electronics
    • /
    • v.18 no.3
    • /
    • pp.863-870
    • /
    • 2018
  • The traditional power control theories for the harmonic reduction methods in multilevel inverters are found to be unreliable under unbalanced load conditions. The unreliability in harmonic mitigation is caused by voltage fluctuations, non-linear loads, the use of power switches, etc. In general, the harmonics are reduced by filters. However, such devices are an expensive way to provide a smooth and fast response to secure power systems during dynamic conditions. Hence, the Decoupled Double Synchronous Reference Frame (DDSRF) theory combined with a State Delay Controller (SDC) is proposed to achieve a harmonic reduction in power systems. The DDSRF produces a sinusoidal harmonic that is the opposite of the load harmonic. Then, it injects this harmonic into power systems, which reduces the effect of harmonics. The SDC is used to reduce the delay between the compensation time for power injection and the generation of a reference signal. The proposed technique has been simulated using MATLAB and its reliability has been verified experimentally under unbalanced conditions.

A Prediction of Number of Patients and Risk of Disease in Each Region Based on Pharmaceutical Prescription Data (의약품 처방 데이터 기반의 지역별 예상 환자수 및 위험도 예측)

  • Chang, Jeong Hyeon;Kim, Young Jae;Choi, Jong Hyeok;Kim, Chang Su;Aziz, Nasridinov
    • Journal of Korea Multimedia Society
    • /
    • v.21 no.2
    • /
    • pp.271-280
    • /
    • 2018
  • Recently, big data has been growing rapidly due to the development of IT technology. Especially in the medical field, big data is utilized to provide services such as patient-customized medical care, disease management and disease prediction. In Korea, 'National Health Alarm Service' is provided by National Health Insurance Corporation. However, the prediction model has a problem of short-term prediction within 3 days and unreliability of social data used in prediction model. In order to solve these problems, this paper proposes a disease prediction model using medicine prescription data generated from actual patients. This model predicts the total number of patients and the risk of disease in each region and uses the ARIMA model for long-term predictions.

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

Probabilistic Estimation of LMR Fuel Cladding Performance Under Transient Conditions

  • Kwon, Hyoung-Mun;Lee, Dong-Uk;Lee, Byung-Oon;Kim, Young ll;Kim, Yong-Soo
    • Nuclear Engineering and Technology
    • /
    • v.35 no.2
    • /
    • pp.144-153
    • /
    • 2003
  • The object of this paper is the probabilistic failure analysis on the cladding performance of WPF(Whole Pin Furnace) test fuel pins under transient conditions, and analysis of the KALIMER fuel pin using the preceding analysis. The cumulative damage estimation and Weibull probability estimation of WPF test are performed. The probabilistic method was adapted for these analyses to determine the effective thickness thinning due to eutectic penetration depth. In the results, it is difficult to assume that a brittle layer depth made by eutectic reaction is all of the thickness reduction due to cladding thinning. About 93% cladding thinning of the eutectic penetration depth is favorable as an effective thickness of cladding. And the unreliability of the KALIMER driver fuel pin under the same WPF test condition is lower than that of the WPF pin because of the higher plenum-fuel volume ratio and lower cladding inner radius vs. thickness ratio. KALIMER fuel pin developed from conceptual design has a more stable transient performance for a failure mechanism due to fission gas buildup than the WPF pin.

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