• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1836-1837
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• 2006

본 논문에서는 차량용 전자제어식 주차 브레이크(Electric Parking Brake, EPB) 시스템의 고장 허용 제어(fault tolerant control)를 위한 고장 안전 기법(fail-safe logic)을 제안한다. 고장 안전 기법의 구현을 위하여 EPB 구동 모터에 흐르는 전류 리플을 측정하여 센서리스 위치 추정을 한다. 추정값과 홀 센서의 출력을 비교하여 잔차(residual)를 발생하고, 이를 이용하여 시스템 내부의 고장을 진단하고 고장 안전 기법을 통하여 전체 시스템의 오작동을 방지한다. 시스템 오작동을 방지하기 위한 고장 안전 기법에 대하여 정의하고 모의실험을 통하여 내부 시스템의 고장이 발생 시 이 기법이 고장을 진단하고 시스템을 안전하게 운영할 수 있음을 확인하였다.

• The Transactions of the Korea Information Processing Society
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• v.3 no.2
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• pp.242-250
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• 1996

Communications on hypercube nodes are done by explicit message routing. So efficient message routing is very important for the performance of hypercube multicomputers. However, hypercube nodes can be faulty due to hardware and/o r software problems, which is called an injured hypercube. A reliable hypercube system should tolerate the problems. One of the methods to enhance reliability on injured hypercube is to use fault-tolerant message routing algorithms. In this paper, we propose a message routing algorithm with possible shortest distance using disjoint paths. To analyze the performance, the algorithm is simulated and evaluated.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06a
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• pp.415-417
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• 2006

분산형 P2P 그리드 시스템을 구축하는데 있어 연산 수행을 위한 노드 구성 기법과 구성된 토플로지에 적합한 연산 수행 보델 및 스케줄링 기법은 필수 요소이다. 하지만 기존 연구에서는 자원 제공자와 휘발성을 고려하지 않은 연산 수행 모델을 사용하였기 때문에 연산의 안정적인 수행이 보장되지 못하고, 시스템의 성능이 떨어지는 문제점이 발생한다. 이에 본 논문에서는 가용성 기반의 자가 조직적 계산 오버레이 네트워크(SelfCON:Self-organizing Computation Overlay Network) 구성 기법과 구성된 토폴로지에 적합한 연산 수행 모델 및 스케줄링 기법을 제안한다. 제안 기법은 자원 제공자 노드의 휘발성을 고려하여 안정성을 높임으로써 전체 연산 성능을 향상시킨다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.3
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• pp.103-109
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• 2003

The validity of measured data is fundamental factor for the power system automation Measured values could have errors that are caused by the communication errors and malfunctioning measuring devices. The accuracy and reliability of measured values at a substation is an important condition for robust and fault tolerant automata. Errors can be reduced by state estimation, however, global reliability of state estimation goes down in case of the existence of some bad data In this paper, a least square state estimation and bad sensor detection algorithm based on chi-square theory, ale proposed and it is applied to a domestic 154kV distribution substations. A simulator together with user friendly graphic users interface is developed using C language and Visual Basic. TCP/IP is equipped for future connection with other operation systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.11
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• pp.1581-1587
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• 2021

As embedded system are used widely and variously, multi-edge system, which multiple edges gather and perform complex operations together, is actively operating. In a multi-edge system, it often occurs that an abnormal operation at one edge is transferred to another edge or the entire system goes down. It is necessary to determine and control edge anomalies in order to prevent system down, but this can be a heavy burden on the resource-limited edge. As a solution to this, we use power consumption data to check the state of the edge device and transmit it based on a QRcode to check and control errors at the server. The architecture proposed in this paper is implemented using 'chip-whisperer' to measure the power consumption of the edge and 'Raspberry Pi 3' to implement the server. As a result, the proposed architecture server showed successful data transmission and error determination without additional load appearing at the edge.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.3
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• pp.217-227
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• 1989

A process control graphic system is proposed as an efficient tool for monitoring the operation of power plant. It uses the multi-processor structure with 60 Kbyte shared memory as an implemental type of the distributed computer system, so that it is flexible, functionally extensible, and applicable to real-time process. The shared memory is used as a real-time database handling the process values and operator's commands. The database files, generated by the user-interactive graphic editor developed for the system or text editor, have the characteristics of simplicity and user-friendliness. The process control graphic system, that can monitor the operation of boiler and function as a backup controller in case of failure in boiler controller, is applied to Ulsan power plant. As a result, it displays the operating data of the boiler process without error by 14 pages of color graphic image according to the operation menu, and additionally functions well as a fault-tolerant control system.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1204-1212
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• 2008

This study enables to troubleshoot the problems of the existing dual system with the help of the implementation of totally dualized fault-tolerant system to L-CTC computer and HADAX, and equipments are simplified and systems are modernized with the addition of the control function, as a upgraded LCP control system, to L-CTC computer on the basis of WINDOWS based O/S switched from DOS environment. An error on Microlok, which is aninterlocking apparatus, forwarded to L-CTC computer ensures to handle the false data during the operation of the system. This paper discusses a sure way to prevent the deterioration of (SMRT) L-CYC system and to bolster its stability with formation of the dual system. Additionally, WINDOW based O/S consisting of L-CTC computer leads to simplification and modernization of facilities and enhances maintenance functions offering centralization for branch offices and machine rooms as well.

• The Transactions of the Korea Information Processing Society
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• v.2 no.6
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• pp.985-994
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• 1995

In this paper, we propose two hot standby architectures which not only provide high system availability but also lose little data on fault occurrence. In order to evaluate the performance of the proposed hot standby architectures, the warm standby architecture. In order to evaluate the performance of the propose d hot standby architectures, the warm standby architecture which is made from the hot standby architecture by eliminating its synchronization unit is considered. After system unavailability for each architecture is computed by using the corresponding Markov state diagram, the results are compared and evaluated. As the results, in most cases, hot standby architectures have higher availability than warm standby architecture. Also, hot standby architecture with external synchronization unit always maintains a little higher availability than hot standby architecture with internal synchronization unit. Active set time and personnel recovery rate for each architecture have little effect on system availability. However, in the case that data recovery time is too long, system availabilities of hot standby architectures and warm standby architecture degrade rapidly. In this case, the performance degradation of hot standby architectures is severe, and system availabilities of hot standby architectures eventually become lower than system availability of warm standby architecture.

• Journal of the Korea Convergence Society
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• v.11 no.8
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• pp.47-53
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• 2020

In the case of a failure due to equipment deterioration in the public address system or a worker's mistake during construction, broadcasting becomes impossible. In this situation, we have designed a more advanced management broadcast system that can broadcast. The broadcasting service is operated using main broadcasting device, and local broadcasting device operates separately only in the local area. If the main broadcasting device becomes inoperable, the procedure for transferring the control activates the device with the local broadcasting devices based on data backed up by the main controller. This paper proposes an improved method of the conventional emergency broadcasting device duplication method. The existing method could not use the standby equipment in the normal state, but in the proposed method, the standby equipment can be used as local broadcasting equipment in usually. This method enables stable system operation while minimizing resource waste due to redundant configuration of expensive devices.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.7
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• pp.3747-3765
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• 2017

Existing authentication mechanisms in cellular mobile communication networks are realized in the upper layer by employing cryptographic techniques. Authentication data are broadcasted over the air in plaintext, enabling attackers to completely eavesdrop on the authentication and get some information about the shared secret key between legitimate nodes. Therefore, reusing the same secret key to authenticate several times results in the secret key's information leakage and high attacking rate. In this paper, we consider the most representative authentication mechanism, Authentication and Key Agreement (AKA), in cellular communication networks and propose an enhanced AKA scheme based on Physical Layer Authentication (AKA-PLA). Authentication responses generated by AKA are no longer transmitted in plaintext but masked by wireless channel characteristics, which are not available to adversaries, to generate physical layer authentication responses by a fault-tolerant hash method. The authenticator sets the threshold according to the authentication requirement and channel condition, further verifies the identity of the requester based on the matching result of the physical layer authentication responses. The performance analyses show that the proposed scheme can achieve lower false alarm rate and missing rate, which are a pair of contradictions, than traditional AKA. Besides, it is well compatible with AKA.