• Title, Summary, Keyword: MTBF(mean time between failures)

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A Study on the Failure Definition for the MTBF Evaluation (MTBF 평가를 위한 고장정의 소고)

  • Kim, Cheol
    • IE interfaces
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    • v.1 no.2
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    • pp.67-74
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    • 1988
  • MTBF (Mean Time Between Failures) is one of the measures to express the reliability for a repairable system, especially for a military weapon system. But MTBF is meaningless without a clear definition of the system failures. In this paper we discuss two failure definitions, one is defined by US Army Training and Doctrine Command jointly with US Army Materiel Command and the other one is used to M1 Tank.

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A Quantitative Reliability Analysis of FPGA-based Controller for applying to Nuclear Instrumentation and Control System (원전적용을 위한 FPGA 기반 제어기의 정량적 신뢰도 평가)

  • Lee, Joon-Ku;Jeong, Kwang-Il;Park, Geun-Ok;Sohn, Kwang-Young
    • The Journal of the Korea institute of electronic communication sciences
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    • v.9 no.10
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    • pp.1117-1123
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    • 2014
  • Nuclear industries have faced unfavorable circumstances such as an obsolescence of the instrumentation and control system, and therefore nuclear society is striving to resolve this trouble fundamentally. FPGAs are currently highlighted as an alternative means for obsolete control systems. Because of the obsolescence-unaffected characteristics, FPGA should be highly reliable in order to be a replacement for PLC (Programmable Logic Controller). Therefore, it is necessary to establish a software development aspect strategy that enhances the reliability of an FPGA-based controller. The reliability analysis including the MTBF (Mean Time Between Failures) is carried out based on the MIL-HDBK-217F. MTBFs are compared with the FPGA-based controller COMMON-Q PLC. As an analysis result, it shows that the reliability of the FPGA-based controller is better than or equal to that of PLC.

Mean Time Between Failures of Web Services on SOAP/HTTP

  • Lee, Sang-Bock
    • Journal of the Korean Data and Information Science Society
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    • v.14 no.3
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    • pp.553-559
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    • 2003
  • The reliability modeling of distributed systems requires a good understanding the reliability of the components. For thousands of web users, competitiveness in web services means a successful presence on the web. Mean time between failures of a web site on SOAP12/HTTP is considered, where SOAP12 is a protocol intended for exchanging structured information in a decentralized, distrbuted environment. Data were collected from statlab.cam.ac.uk/webstat/stat.html via the internet.

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An Application-Level Fault Tolerant System For Synchronous Parallel Computation (동기 병렬연산을 위한 응용수준의 결함 내성 연산시스템)

  • Park, Pil-Seong
    • Journal of Internet Computing and Services
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    • v.9 no.5
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    • pp.185-193
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    • 2008
  • An MTBF(mean time between failures) of large scale parallel systems is known to be only an order of several hours, and large computations sometimes result in a waste of huge amount of CPU time, However. the MPI(Message Passing Interface), a de facto standard for message passing parallel programming, suggests no possibility to handle such a problem. In this paper, we propose an application-level fault tolerant computation system, purely on the basis of the current MPI standard without using any non-standard fault tolerant MPI library, that can be used for general scientific synchronous parallel computation.

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A design of the fixed duration reliability demonstration test from the viewpoint of operators (운영자 관점에서의 철도차량의 고정기간 신뢰성 입증 시험의 설계)

  • Kim, Jong-Woon;Chung, In-Soo;Park, Jun-Seo
    • Proceedings of the KSR Conference
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    • pp.577-581
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    • 2009
  • The fixed duration test has been widely used in the reliability demonstration test for rolling stocks. This article deals with how to design the test statistics, acceptance criteria and the fixed duration of the MTBF(Mean Time Between Failures) demonstration test considering the consumer risk. Numerical examples are given to illustrate the dependence of the consumer risk on the test duration and MTBF requirement.

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Analysis of failure rate according to capacitor position of bidirectional converter (양방향 컨버터의 커패시터 위치에 따른 고장률 분석)

  • Kim, Ye-rin;Kang, Feel-soon
    • Journal of IKEEE
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    • v.23 no.1
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    • pp.261-265
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    • 2019
  • We analyze the failure rate change of a conventional bidirectional converter and a modified one which moves an output capacitor towards propulsion battery. We analysis of the circuit structural homogeneity and the difference between both converters, and confirm that the capacitor working voltage is reduced by changing the capacitor position. After obtaining the capacitor failure rate according to voltage stress factor and operating temperature, it is applied to the fault-tree of the bidirectional converter to obtain the overall failure rate of the converter. We analyzes the advantages and disadvantages of design changes by comparing and analyzing the failure rate and mean time between failures (MTBF) according to operating temperature and capacitance value.

A Study on the Failure and Life Assessment of High Speed Spindle (고속주축의 고장 및 수명평가에 관한 연구)

  • Lee, Tae Hong
    • Journal of the Korean Society for Precision Engineering
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    • v.31 no.1
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    • pp.67-73
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    • 2014
  • A reliability evaluation or prediction can be defined as MTBF which stands for mean time between failures (Exclusively for repairable failures). Spindle system has huge effect on performance of machine tools and working quality as well as is required of high reliability. Especially, it takes great importance in producing automobiles which includes a large number of working processes. However, it is unusually difficult to predict reliability because there are lack of data and research about reliability of spindle system. Standards and methods of examinations for reliability evaluation of machine tools are scarce at local and abroad as well. Therefore, this research is meant to improve the reliability of spindle system before mass produced with developing standards of reliability and methods of examinations through FMEA to assess reliability of spindle system in prototype stages of developing high speed spindle system of machining center.

Reliability Prediction of Digital Protection Relay (디지털 보호계전기의 신뢰도 분석)

  • Song, In-Jun;An, Yong-Ho;Yang, Gwi-Jang;Jun, Kwang-Sig
    • Proceedings of the KIEE Conference
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    • pp.377-378
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    • 2008
  • 한전에서는 계통보호 설비의 신뢰도 확보를 위해 디지털 보호설비 사용을 확대하고 있으며, 이에 따른 합리적인 보호설비 교체기준을 설정하려고 한다. 본 논문에서는 디지털 보호계전기의 교체기준 설정을 위해 디지털 보호 계전기(Digital Distance Relay)와 구성모듈에 대한 고장률(Failure rate)과 평균수명(Mean Time between Failures, MTBF), 그리고 시간에 따른 신뢰도를 분석하였다. 수명예측방법은 MIL-HDBK-217F, Notice 2의 부품스트레스분석방법(Part Stress Analysis Method) 사용하였다.

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Prediction of MTBF Using the Modulated Power Law Process

  • Na, Myung-Hwan;Son, Young-Sook;Yoon, Sang-Hoo;Kim, Moon-Ju
    • Journal of the Korean Data and Information Science Society
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    • v.18 no.2
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    • pp.535-541
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    • 2007
  • The Non-homogeneous Poisson process is probably the most popular model since it can model systems that are deteriorating or improving. The renewal process is a model that is often used to describe the random occurrence of events in time. But both these models are based on too restrictive assumptions on the effect of the repair action. The Modulated Power Law Process is a suitable model for describing the failure pattern of repairable systems when both renewal-type behavior and time trend are present. In this paper we propose maximum likelihood estimation of the next failure time after the system has experienced some failures, that is, Mean Time Between Failure for the MPLP model.

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Fault-tree based reliability analysis for bidirectional converter (고장나무를 이용한 양방향 컨버터의 신뢰성 분석)

  • Heo, Dae-ho;Kang, Feel-soon
    • Journal of IKEEE
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    • v.23 no.1
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    • pp.254-260
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    • 2019
  • The failure rate of bidirectional dc-to-dc converter is predicted through the failure mode and effect analysis (FMEA) and the fault-tree analysis (FTA) considering the operational risk. In order to increase the driving voltage of the electric vehicle efficiently, the bidirectional converter is attached to the front of the inverter. It has a boost mode for discharging battery power to the dc-link capacitor and a buck mode for charging the regenerative power to the battery. Based on the results of the FMEA considering the operating characteristics of the bidirectional converter, the fault-tree is designed considering the risk of the converter. After setting the design parameters for the MCU for the electric vehicle, we analyze the failure rate of the capacitor due to the output voltage ripple and the inductor component failure rate due to the inductor current ripple. In addition, we obtain the failure rate of major parts according to operating temperature using MIL-HDBK-217F. Finally, the failure rate and the mean time between failures (MTBF) of the converter are predicted by reflecting the part failure rate to the basic event of the fault-tree.