• 한국정보처리학회논문지
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• 제6권8호
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• pp.2233-2244
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• 1999

내장 실시간 시스템의 경우 시스템의 오류로 인한 비정상적인 운행이 커다란 경제적 피해나 인명피해를 초래할 수 있으므로 시스템의 고 신뢰도 보장은 필수적이다. 이에 많은 결함허용 방법들이 연구되었는데 이들은 대부분 단위 객체에서 발생하는 오류만 감지하고 단위 객체 수준에서 오류를 처리하는 객체 수준 결함 허용 방법이다. 그런데, 내장 실시간 시스템이 점점 더 복잡해지고 커짐에 따라 객체 수준 결함 허용 방법만으로는 감지하거나 처리할 수 없는 결함과 오류가 존재한다. 따라서, 여러 객체들의 상태에 대한 분석을 통해서 시스템의 상태가 정상인지 비정상인지를 판단하고 오류가 발생했을 때에는 오류의 원인이 되는 결함을 찾은 다음 알맞은 복구 및 재배치 방법을 결정하는 시스템 수준 결함 허용이 필요하다. 본 논문에서는 객체 수준 결함 허용 기능을 제공하는 RobustRTO(Robust Real-Time Object)와 시스템 수준 결함 허용 기능을 제공하는 RMO(Region Monitor real-time Object)를 제안하고 이들을 이용하여 객체 수준 결함 허용 기능뿐만 아니라 시스템 수준 결함 허용 기능도 갖는 고 신뢰도의 결함 허용 시스템을 모델링할 수 있음을 보인다. 본 논문은 객체 모델의 장점과 실시간성 표현이 용이한 실시간객체(RTO 또는 Real-Time Object) 모델에 기반한다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.304-308
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• 2004

One of the obstacles for a magnetic bearing to be used in the wide range of industrial applications is the failure modes associated with magnetic bearings. These failure modes include power amplifier faults, position sensor faults, and the malfunction of controllers. Fault-tolerant magnetic bearing systems have been proposed so that the system can operate in spite of some faults. In this paper, we designed and tested a fault-tolerant magnetic bearing system. The system can cope with the actuator faults as well as the faults in position sensors, which are the two major fault modes in a magnetic bearing system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권10호
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• pp.4774-4796
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• 2018

Wireless sensor networks are composed of a large number of inexpensive and tiny sensors used in different areas including military, industry, agriculture, space, and environment. Fault tolerance, which is considered a challenging task in these networks, is defined as the ability of the system to offer an appropriate level of functionality in the event of failures. The present study proposed an intelligent throughput descent and distributed energy-efficient mechanism in order to improve fault tolerance of the system against soft and permanent faults. This mechanism includes determining the intelligent neighborhood radius threshold, the intelligent neighborhood nodes number threshold, customizing the base paper algorithm for distributed systems, redefining the base paper scenarios for failure detection procedure to predict network behavior when running into soft and permanent faults, and some cases have been described for handling failure exception procedures. The experimental results from simulation indicate that the proposed mechanism was able to improve network throughput, fault detection accuracy, reliability, and network lifetime with respect to the base paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.2429-2432
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• 2000

Adaptive filter algorithm has been used for plant identifier and noise cancellation. This algorithm has been researched for performance enhancement of filtering. The design and development of a reliable system has been becoming a key issue in industry field because the reliability of a system is considered as an important factor to perform the system's function successfully. And the computing with reliability and fault tolerance is a important factor in the case of aviation and nuclear plant. This paper presents design of reliable adaptive filter with fault tolerance. Generally, redundancy is used for reliability. In this case it needs computing or circuit for voting mechanism or computing for fault detection or switching part. But this presented Filter is not in need of computing for voting mechanism, or fault detection. Therefore it has simple computing, and practicality for application. And in this paper, reliability of adaptive filter is analyzed. The effectiveness of the proposed adaptive filter is demonstrated to the case studies of plant identifier and noise cancellation by using DSP.

• 정보처리학회논문지D
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• 제10D권6호
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• pp.991-998
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• 2003

CORBA를 사용하는 실시간 시스템의 안정성을 높이기 위한 방법은 관점에 따라 여러 가지가 있다. 그 중에서 본 논문은 CORBA 표준을 구현한 시스템이 실시간 정보를 처리할 경우 발생하는 객체 장애 시에 지속적인 서비스를 가능케 하는 방법을 제시한다. 즉, 3 tier 소프트웨어 아키텍쳐 환경에서 발생하는 객체 장애에 효율적으로 대처하는 방법을 고찰한다. 객체 장애를 고려하여 안정성을 높이는 방법으로서 객체를 복제(replication)하는 방법이 가능하다. 본 논문에서는 이와 함께 Fault Tolerant CORBA(FT-CORBA) 의 장애 복구까지 시스템을 지속적으로 운영하기 위한 방법을 고찰함으로써 궁극적으로 시스템의 안정성을 향상하고 이에 따라 서비스의 연속성을 유지시킬 수 있는 방법을 제시한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.959-964
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• 1993

We developed fault diagnosis fuzzy expert system for ACS(Advanced Control System). ACS is a DCS(Distributed Control System) with advanced control algorithm fault tolerance capabilities, fault diagnosis functions, and so on. Fuzzy expert system developed for an ACS in this paper gives an operator alarm signal depending on the state of process value and manipulated value, and the cause of alarm in real time. Simple experiment result with several rules for the-fault-diagnosis of drum level loop in Seoul-Power-Plant.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권1호
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• pp.35-57
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• 2021

Fog computing aims to provide the solution of bandwidth, network latency and energy consumption problems of cloud computing. Likewise, management of data generated by healthcare IoT devices is one of the significant applications of fog computing. Huge amount of data is being generated by healthcare IoT devices and such types of data is required to be managed efficiently, with low latency, without failure, and with minimum energy consumption and low cost. Failures of task or node can cause more latency, maximum energy consumption and high cost. Thus, a failure free, cost efficient, and energy aware management and scheduling scheme for data generated by healthcare IoT devices not only improves the performance of the system but also saves the precious lives of patients because of due to minimum latency and provision of fault tolerance. Therefore, to address all such challenges with regard to data management and fault tolerance, we have presented a Fault Tolerant Data management (FTDM) scheme for healthcare IoT in fog computing. In FTDM, the data generated by healthcare IoT devices is efficiently organized and managed through well-defined components and steps. A two way fault-tolerant mechanism i.e., task-based fault-tolerance and node-based fault-tolerance, is provided in FTDM through which failure of tasks and nodes are managed. The paper considers energy consumption, execution cost, network usage, latency, and execution time as performance evaluation parameters. The simulation results show significantly improvements which are performed using iFogSim. Further, the simulation results show that the proposed FTDM strategy reduces energy consumption 3.97%, execution cost 5.09%, network usage 25.88%, latency 44.15% and execution time 48.89% as compared with existing Greedy Knapsack Scheduling (GKS) strategy. Moreover, it is worthwhile to mention that sometimes the patients are required to be treated remotely due to non-availability of facilities or due to some infectious diseases such as COVID-19. Thus, in such circumstances, the proposed strategy is significantly efficient.

• 한국공간정보시스템학회 논문지
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• 제11권2호
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• pp.13-18
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• 2009

This paper presents the implementation procedure of encoding and decoding algorithms for Tornado code that can provide fault tolerance for storage and transmission system. The degree distribution satisfying heavy tail distribution is produced. Based on this distribution, a good random irregular bipartite graph is attained after plenty of trails. Such graph construction is proved to be efficient, and the experiments also demonstrate that the implementation obtains good performance in terms of decoding overhead.

• 한국산업융합학회 논문집
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• 제25권6_2호
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• pp.1003-1008
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• 2022

This paper proposes a method related to fault tolerance operation and characteristic analysis of asymmetric 6-phase permanent magnet synchronous motor. In general, motor drive systems with multi-phase structures can be continuously operated despite a reduction of power and speed by using a phase changeover or control techniques according to the failures. As a result, it is widely used in industrial fields such as aviation and defense, which require high efficiency and high reliability. In this paper, the second order ripple of the electrical fundamental freuqnecy occurs in the dq-axis currents of the synchronous coordinate system through mathematical analysis according to the switch open of the dual 3-phase inverter. Therefore, the fault tolerant operation method is presented by applying the fault detection method with a constant cycle for continuous operations. The effectiveness of the proposed fault tolerance operation method is verified through the several experiments.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2005년도 한국컴퓨터종합학술대회 논문집 Vol.32 No.1 (A)
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• pp.772-774
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• 2005

안전성이 강조되는 실시간 시스템에서 시스템이 시간의 제약을 만족해야만 한다. 실시간 시스템에서 오류는 잘못된 응답 뿐 만이 아니라 시간적으로 늦은 응답에 대해서도 오류로 분류를 할 수가 있다. 이런 오류들을 모니터하기 위해서 본 논문에서는 커널에 Timed Conformance Monitor를 모듈로 추가하였다. Timed Conformance Monitor를 통해서 실시간 태스크가 시간의 제약을 만족하는지를 분석하고 또한 분석 결과에 따라 오류를 처리할 수 있는 Fault Handler를 추가하여 실시간 시스템에 대한 Fault Tolerance를 보장해 줄 수 있다.