• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.6
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• pp.995-1000
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• 2017

In this paper, we present an electrical arc detection algorithm using the mash-up analysis technique which is the core technology for the autonomous electrical safety management system(AESMS) of the multi-unit dwellings. The mash-up analysis technique analyzes the voltage, load current, zero phase current data simultaneously to judge arc faults. In order to develop the arc fault detection algorithm, the characteristics of series arc and parallel arc were analyzed. Also, we propose the mash-up analysis technique that analyzes waveforms of voltage, load current, and zero phase current at the same time. The arc fault detection algorithm was developed using the mash-up analysis technique. The developed algorithm can prevent electrical disasters in an effective way through accident prediction, and it will be used as a basic technology to introduce an autonomous electrical safety management system.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.393-393
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• 2000

FTA(Fault Tree Analysis) is a safety analysis method that focuses on one particular accident or main system failure and provides a method of determining causes of that event. While most of the statistical and cut set analysis have been automated, actual construction of the fault-tree is usually done manually. Manual construction of the fault-tree is extremely time consuming and it requires high level of expertise and experience. In addition to the time involved, different analyst often produces different fault-trees either by incorrect logic or omission of certain events. Automatic fault-tree construction system can be efficient in solving above problems. This study presents a new Digraph-FT conversion algorithm that leads automatic FTA system.

• Journal of Auto-vehicle Safety Association
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• v.15 no.2
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• pp.13-20
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• 2023

This paper presents a fault tolerant control strategy for Steer-by-Wire (SbW) systems. Among many problems to be solved before commercialization of SbW systems, maintaining reliability and fault tolerance in such systems are the most pressing issues. In most previous studies, dual steering motors are used to achieve actuation redundancy. However, relatively few studies have been conducted to introduce fault tolerant control strategies using rear wheel steering system. In this work, an actuator fault in front wheel steering is compensated by active rear wheel steering. The proposed fault tolerant control algorithm consists of disturbance observer and sliding mode control. The fault tolerant control performance of the proposed approach is validated via computer simulation studies with Carsim vehicle dynamics software and MATLAB/Simulink.

• Nuclear Engineering and Technology
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• v.33 no.6
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• pp.596-604
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• 2001

This paper quantitatively presents the effects of important factors of the probabilistic safety assessment (PSA) of safety-critical digital systems. The result which is quantified using fault tree analysis methodology shows that these factors remarkably affect the system safety. In this paper we list the factors which should be represented by the model for PSA. Based on the PSA experience, we select three important factors which are expected to dominate the system unavailability. They are the avoidance of common cause failure, the coverage of fault tolerant mechanisms and software failure probability. We Quantitatively demonstrate the effect of these three factors. The broader usage of digital equipment in nuclear power plants gives rise to the safety problems. Even though conventional PSA methods are immature for applying to microprocessor-based digital systems, practical needs force us to apply it because the result of PSA plays an important role in proving the safety of a designed system. We expect the analysis result to provide valuable feedback to the designers of digital safety- critical systems.

• Geomechanics and Engineering
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• v.23 no.2
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• pp.127-137
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• 2020

To study the reverse fault formation process and the stress evolution feature, a simulation test system of reverse fault formation is developed based on the analysis of reverse fault formation mechanism. The system mainly consists of simulation laboratory module, operation console and horizontal loading control system, and data monitoring system. It can represent the fault formation process, induce fault crack initiation and simulate faults of different throws. Simulation tests on reverse fault formation process are conducted by using the simulation test system: horizontal loading is added to one side of the model. the bottom rock layer cracks under the effect of the induction device. The crack dip angle is about 29°. A reverse fault is formed with the expansion of the crack dip angle towards the upper right along the fracture surface and the slippage of the hanging wall over the foot wall. Its formation process unfolds five stages: compressive deformation of rock, local crack initiation, reverse fault penetration, slippage of the hanging wall over the foot wall and compaction of fault plane. There is residual structural stress inside rock after fault formation. The study methods and results have guiding and referential significance for further study on reverse fault formation mechanism and rock stress evolution.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.1
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• pp.232-238
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• 2016

This paper presents protection techniques against electric shock in low voltage DC(direct current) grounding systems depending on the analysis of earth fault current paths. Firstly, the comparison between alternating current and direct current on human was conducted, and current threshold values for each current path and for long duration were analyzed. Secondly, the analyses of the earth fault current flows were performed depending on the grounding types and earth fault conditions. Lastly, based on these analyses, adequate protection measures of electric shock depending on low voltage DC grounding types were provided.

• Journal of the Korean Society of Safety
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• v.22 no.6
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• pp.41-45
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• 2007

Short circuit and ground fault account for the primary causes of electrical fires. In this research, real-scale experiments were conducted to assess the possibility of electrical fires due to these causes. The experiment conditions were identical with an actual fire accident, in which the power cable was supported by an iron fence. The purposes of this research are to investigate the short circuit caused by wire cutting, the conductivity of the iron fence depending on its coating conditions, and the ground fault of one wire or two wires in an effort to reconstruct the fire accident. The test results show that, owing to the instant operation of circuit breaker in the moment of short circuit or ground fault, the generated ignition energy is far less than necessary to start an ignition. Therefore it is concluded that electrical fire is highly unlikely if the electric system is protected by a circuit breaker with normal functions.

• Proceedings of the Safety Management and Science Conference
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• 2000.05a
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• pp.207-215
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• 2000

This study deals with the application of knowledge-engineering and a methodology for the assessment & measurement of reliability, availability, maintainability, and safety of industrial systems using fault-tree representation. A fuzzy methodology for fault-tree evaluation seems to be an alternative solution to overcome the drawbacks of the conventional approach(insufficient information concerning the relative frequences of hazard events). To improve the quality of results, the membership functions must be approximated based on heuristic considerations. The purpose of this Is to describe the knowlwdge engineering approach, directed to integrate the various sources of knowledge involved in a FTA.

• Journal of the Korea Safety Management & Science
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• v.2 no.2
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• pp.1-10
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• 2000

This study deals with the application of knowledge engineering and a methodology for the assessment and measurement of reliability, availability, maintainability, and safety of industrial systems using fault-tree representation. A fuzzy methodology for fault-tree evaluation seems to be an alternative solution to overcome the drawbacks of the conventional approach (insufficient information concerning the relative frequence of hazard events). To improve the quality of results, the membership functions must be approximated based on heuristic considerations. The purpose of this study is to describe the knowledge engineering approach, directed to integrate the various sources of knowledge involved in a FTA.

• Proceedings of the KIEE Conference
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• 2009.04a
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• pp.205-207
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• 2009

In 2007, 9,128 fires are attributed to electrical equipments. These fires resulted in 29 deaths and 262 injuries. Arc-faults were one of the major causes of these fires. When an unintended arc-fault occurs, it generates intense heat that can easily ignite surrounding combustibles. Conventional circuit breakers only respond to overloads, short circuits, and leakage currents. Therefore, the breakers do not protect against arcing conditions. This paper presents results obtained in experiments on ignition behavior of wire by series arc fault currents and techniques developed to detect the arc-faults. The developed technique was tested after installation to make sure they are working properly and protecting the circuit. If the developed arc detecting technique is applied, the electrical fires caused by an arc-fault can be reduced.