• Title/Summary/Keyword: Fault Event

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Fault-tolerant robust supervisor for timed discrete event systems

  • Park, Seong-Jin;Li, Jong-Tae
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.411-413
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    • 1997
  • This paper presents the problem of fault-tolerant robust supervisory control of timed discrete event systems (DESs). First the concept of faults is quantitatively defined in timed DESs and fault tolerable event sequences are presented as a desired legal language. Given a timed DES with model uncertainty, the conditions for the existence of a supervisor which always guarantees fault tolerable event sequences embedded in the system are derived.

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Fault tolerant supervisory control system and automated failure diagnosis

  • Cho, K.H.;Lim, J.T.
    • 제어로봇시스템학회:학술대회논문집
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    • 1995.10a
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    • pp.35-38
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    • 1995
  • We proposed in this paper a systematic way for analyzing discrete event dynamic systems to classify faults and failures quantitatively and to find tolerable fault event sequences embedded in the system. An automated failure diagnosis scheme with respect to the nominal normal operating event sequences and the supervisory control problem for tolerable fault event sequences is presented. Moreover the supervisor failure diagnosis problem with respect to the tolerable fault event sequences is considered. Finally, a plasma etching system example is presented.

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Reliability Assessment of Railway Power System by using Tree Architecture (Tree 구조를 이용한 전철급전시스템의 신뢰도 평가)

  • Cha, Jun-Min;Ku, Bon-Hui
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.1
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    • pp.9-15
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    • 2010
  • As catenary supply electric power directly to the railway system, it is very important to prevent an accident of a catenary for appropriate train operation. This paper proposed the assessment the outage data for "British Catenary Safety Analysis Report" and Korean data to compare the reliability of the railway system. The analyzed data were applied to Event Tree and Fault Tree algorithm to calculate the reliability indices of railway system. Event tree is created and gate results of fault tree analysis are used as the source of event tree probabilities. Fault tree represents the interaction of failures and basic events within a system. Event Tree and Fault Tree analysis result is helpful to assess the reliability to interpreted. The reliability indices can be used to determine the equipment to be replaced for the entire system reliability improvement.

A New Test Generation Algorithm Using a Backtrace Fault Simulation (역추적 결함 시뮬레이션을 이용한 새로운 테스트 생성 알고리즘)

  • 권기창;백덕화;권기룡
    • KSCI Review
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    • v.2 no.1
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    • pp.121-129
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    • 1995
  • Fault simulation of logic circuits is an important part of the test-generation process. It is used for the propose of generation fault dictionaries or for the verification of the adequacy of tests. In this paper, a backtrace fault simulation is proposed to test generation. This is consists of 3 part ; initialization phase for given circuit, backtrace fault simulation phase to find fault list and reevaluation phase to list event. The main idea of this algorithm is to retain a minimum fault list by cutting uncontrollable lines of path when a logic event occurs in backward tracing phases. And the simulator is revaluates a fault list associated with the output of an element only if logic event occurs at any of its inputs when a list event occurs at one of its primary inputs. It reguires a O(n) memory space complexity. where n is a number of signal lines for the given circuits. Several examples are given to illustrate the power of this algorithm.

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Geometric Analysis of Minor Faults and Paleostress Reconstruction around the Dongnae Fault (동래단층 주변 소단층의 분포 특성과 고응력장 복원)

  • 조용찬;장태우;이정모
    • Journal of the Earthquake Engineering Society of Korea
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    • v.2 no.4
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    • pp.41-52
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    • 1998
  • The Dongnae Fault in the southeastern part of the Korean Peninsular is not a single fault but a complex fault zone composed of numerous minor faults. In order to deduce the paleostress tensor evolving the Dongnae Fault, we measured 329 faults in outcrops around the fault zone and analyzed the geometries of them. Most of them are steeply dipping(>65˚) and fall into three groups striking N10E, N30E and N70E. More than one half of them show the rakes less than 30˚ Paleostress tensor analysis using the collected fault data has been conducted with the Angelier's direct inversion method and the Choi's method. As result, four different principal paleostress axes each of which subtends an independent tectonic event are found. They are; (1) NNE-SSW compression and ESE-WNW extension (Event I), (2) NNE-SSW extension (Event II), (3) ESE-WNW extension (Event III) and (4) ENE-WSW compression and NNW-SSE extension (Event IV) in chronology. Therefore, the tectonic movement around the Dongnae Fault was firstly governed by strike-slip faulting related to Event I. Afterward, normal faults were formed by Event II and Event III. Finally, the dextral strike-slip faults along the major trace of the Dongnae Fault were formed in NNE direction related to Event IV.

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Feasibility Study on the Fault Tree Analysis Approach for the Management of the Faults in Running PCR Analysis (PCR 과정의 오류 관리를 위한 Fault Tree Analysis 적용에 관한 시범적 연구)

  • Lim, Ji-Su;Park, Ae-Ri;Lee, Seung-Ju;Hong, Kwang-Won
    • Applied Biological Chemistry
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    • v.50 no.4
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    • pp.245-252
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    • 2007
  • FTA (fault tree analysis), an analytical method for system failure management, was employed in the management of faults in running PCR analysis. PCR is executed through several processes, in which the process of PCR machine operation was selected for the analysis by FTA. The reason for choosing the simplest process in the PCR analysis was to adopt it as a first trial to test a feasibility of the FTA approach. First, fault events-top event, intermediate event, basic events-were identified by survey on expert knowledge of PCR. Then those events were correlated deductively to build a fault tree in hierarchical structure. The fault tree was evaluated qualitatively and quantitatively, yielding minimal cut sets, structural importance, common cause vulnerability, simulation of probability of occurrence of top event, cut set importance, item importance and sensitivity. The top event was 'errors in the step of PCR machine operation in running PCR analysis'. The major intermediate events were 'failures in instrument' and 'errors in actions in experiment'. The basic events were four events, one event and one event based on human errors, instrument failure and energy source failure, respectively. Those events were combined with Boolean logic gates-AND or OR, constructing a fault tree. In the qualitative evaluation of the tree, the basic events-'errors in preparing the reaction mixture', 'errors in setting temperature and time of PCR machine', 'failure of electrical power during running PCR machine', 'errors in selecting adequate PCR machine'-proved the most critical in the occurrence of the fault of the top event. In the quantitative evaluation, the list of the critical events were not the same as that from the qualitative evaluation. It was because the probability value of PCR machine failure, not on the list above though, increased with used time, and the probability of the events of electricity failure and defective of PCR machine were given zero due to rare likelihood of the events in general. It was concluded that this feasibility study is worth being a means to introduce the novel technique, FTA, to the management of faults in running PCR analysis.

FTA 기법을 이용한 Compresson고장 진단

  • 배용환
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1993.04b
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    • pp.305-309
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    • 1993
  • The application of fault tree technique to the analysis of compressor failure is considered. The techniques involve the decomposition of the system into a logic diagram or fault tree in whichcertain basic or primary events lead to a specified top event which signifiss the total failure of the system. The fault trees are used to obtain miniumal cut sets from whichthe modes of system failure and, hence the reliability for the top event can be calculated. The method of constructing fault trees and the subsequent estimation of reliability of the system is illustrated through a compressor failure. FTA is roved to be efficient to investigate the compressor fault train.

Active Fault Study of the Yangsan Fault System and Ulsan Fault System, Southeastern Part of the Korean Peninsula

  • Kyung, Jai-Bok;Lee, Kie-Hwa
    • Journal of the Korean Geophysical Society
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    • v.9 no.3
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    • pp.219-230
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    • 2006
  • Since the key issue that 'the Yangsan fault is seismically an active fault" was raised in 1983, thegeological and geomorphological studies of active fault have been made by many researchers. These studies are mainly focused on the Yangsan fault system(YFS) and Ulsan fault system(UFS) due to many historical earthquakes occurred in this area. There are two different types of active faultings under the ENE-WSW horizontal stress field in the southeastern part of the Korean Peninsula. The NNE-trending YFS is the most prominent right-lateral strike-slip fault and has a continuous trace about 200 km long. Some part of this system has been active during the late Quaternary with evidences clearly recognized on both the northern (Yugyeri and Tosung-ri areas) and southern parts (Eonyang to Tongdosa area) of the YFS. in the southern part, the estimated vertical slip rate is about 0.02 - 0.07 mm/yr, and the lateral slip rate may be several times larger than the vertical rate. The most recent event occurred prior to deposition of Holocene alluvium, in the northern part, the fault trend locally changes to almost N-S, dips to the east and has reverse movement. The average vertical slip rate is estimated to be less than 0.1 mm/yr. The most recent event probably occurred after 1314 years BP (AD 536). The NNW-SSE (or N-S) trending UFS is a predominantly reverse fault that built up U-ie eastern mountain and has been active during U-ie late Quaternary. The fault trace is not straight but irregularly undulates along the foot of the mountain on the east. From the disturbed terraces along U-ie fault, the average vertical slip rate on U-iis system is estimated to be about 0.08.13mm/yr. The latest event is not well studied, but seems to have occurred after the last glacial maximum in the Malbang fault and 14,000 years BP in the Kalgok fault of the UFS. However, important issues such as fault segmentation, recurrence interval, age of Quaternary deposits need further studies.

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Simulation-Based Risk Analysis of Integrated Power System (시뮬레이션을 이용한 통합전력시스템의 위험도 분석)

  • Lee, Ji Young;Han, Young Jin;Yun, Won Young;Bin, Jae Goo
    • Journal of Korean Institute of Industrial Engineers
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    • v.42 no.2
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    • pp.151-164
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    • 2016
  • In this paper, we deal with a risk analysis for an IPS (Integrated power system) and propose a simulation model combining the fault tree and event tree in order to estimate the system availability and risk level, together. Firstly, the basic information such as operational scenarios, physical structure, safety systems is explained in order to make the fault tree and event tree of the IPS. Next, we propose a discrete-event simulation model using a next-event time advance technique to advance the simulation time. Also the state transition and activity diagrams are explained to represent the relationship between the objects. By numerical examples, the redundancy allocation is considered in order to decrease the risk level of the IPS.

A Study on Data Pre-filtering Methods for Fault Diagnosis (시스템 결함원인분석을 위한 데이터 로그 전처리 기법 연구)

  • Lee, Yang-Ji;Kim, Duck-Young;Hwang, Min-Soon;Cheong, Young-Soo
    • Korean Journal of Computational Design and Engineering
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    • v.17 no.2
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    • pp.97-110
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    • 2012
  • High performance sensors and modern data logging technology with real-time telemetry facilitate system fault diagnosis in a very precise manner. Fault detection, isolation and identification in fault diagnosis systems are typical steps to analyze the root cause of failures. This systematic failure analysis provides not only useful clues to rectify the abnormal behaviors of a system, but also key information to redesign the current system for retrofit. The main barriers to effective failure analysis are: (i) the gathered data (event) logs are too large in general, and further (ii) they usually contain noise and redundant data that make precise analysis difficult. This paper therefore applies suitable pre-processing techniques to data reduction and feature extraction, and then converts the reduced data log into a new format of event sequence information. Finally the event sequence information is decoded to investigate the correlation between specific event patterns and various system faults. The efficiency of the developed pre-filtering procedure is examined with a terminal box data log of a marine diesel engine.