• 제어로봇시스템학회논문지
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• 제10권10호
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• pp.899-906
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• 2004

In this paper, fault tolerant algorithm is presented for a servo manipulator system. For fault tolerance of a servo manipulator system, reconfiguration algorithm accommodating a motor's failure has been presented. The algorithm considers a transport's degree of freedoms as redundant joints of a servo manipulator. The reconfiguration algorithm recovers the end effector's motion in spite of one motor's failure A modified pseudo inverse redistribution method has been proposed for the reconfiguration algorithm. Numerical examples and hardware tests have been presented to verify the proposed methods.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2376-2378
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• 2002

Redundant Programmable Logic Controllers are used in practice with the aim of achieving higher degree of availability or fault tolerance. In the paper a proposed Multiplex-PC is controled for fault tolerance design. In order to select a Different-Vender by a Supervisor computer, a Multiplex-PC is designed by TCP/IP internet protocol[1]. Because TCP/IP internet protocol can not connect to CPU. We use TCP/IP internet protocol to join CPU. We have to use TCP congestion control to select Different-Vender [4]. The reliability of the fault tolerant is measured with MTBF(Mean Time Between Failures)[3].

• 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.

• 대한기계학회논문집A
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• 제32권3호
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• pp.232-239
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• 2008

The position sensors used in a magnetic bearing system are desirable to provide some degree of fault-tolerance as the rotor position is necessary for the feedback control to overcome the open-loop instability. In this paper, we propose an inductive position sensor that can cope with a partial fault in the sensor. The sensor has multiple poles which can be combined to sense the in-plane motion of the rotor. When a high-frequency voltage signal drives each pole of the sensor, the resulting current in the sensor coil contains information regarding the rotor position. The signal processing circuit of the sensor extracts this position information. In this paper, we used the magnetic circuit model of the sensor that shows the analytical relationship between the sensor output and the rotor motion. The multi-polar structure of the sensor makes it possible to introduce redundancy which can be exploited for fault-tolerant operation. The proposed sensor is applied to a magnetically levitated turbo-molecular vacuum pump. Experimental results validate the fault-tolerance algorithm.

• 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.

• 한국통신학회논문지
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• 제17권11호
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• pp.1279-1289
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• 1992

고장 방지 시스템은 하드웨어나 소프트웨어의 여분 (Redundancy)을 이용하여 신뢰도(Reliability) 및 안전도(Safety)를 향상 시킨다. 시스템의 대상 영역(application areas)에 따라 고장 마스크(fault mask), 고장검출(fault detection), 고장 확인(fault identification)등의 기법을 선택하여 이용한다. 본 연구에서는 최소의 하드웨어와 소프트웨어의 여분을 이용하는 DMR(Double Modular Redundancy) 시스템을 대기 모듈(standby module)과 Fail-safe 모듈로 동작 시킬때 신뢰도와 안전도의 특성을 비교 제시한다. 또한 자기 진단 프로그램의 과도 오류 방지 능력에 대한 시스템의 MTTF를 비교함으로서 과도 오류를 취급하는 효과적인 방법을 제시하였다.

• Journal of information and communication convergence engineering
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• 제19권3호
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• pp.175-179
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• 2021

Enhancing the reliability of the system is important for recent system-on-chip (SoC) designs. This importance has led to studies on fault diagnosis and tolerance. Fault-injection (FI) techniques are widely used to measure the fault-tolerance capabilities of resilient systems. FI techniques suffer from limitations in relation to environmental conditions and system features. Moreover, a hardware-based FI can cause permanent damage to the target system, because the actual circuit cannot be restored. Accordingly, we propose a simulation-based FI framework based on the Verilog Procedural Interface for measuring the failure rates of SoCs caused by soft errors. We execute five benchmark programs using an ARM Cortex M0 processor and inject soft errors using the proposed framework. The experiment has a 95% confidence level with a ±2.53% error, and confirms the reliability and feasibility of using proposed framework for fault analysis in SoCs.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권11호
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• pp.3030-3049
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• 2023

With the development and wide application of hybrid network computing modes like cloud computing, edge computing and fog computing, the customer service requests and the collaborative optimization of various computing resources face huge challenges. Considering the characteristics of network environment resources, the optimized deployment of service resources is a feasible solution. So, in this paper, the optimal goals for deploying service resources are customer experience and service cost. The focus is on the system impact of deploying services on load, fault tolerance, service cost, and quality of service (QoS). Therefore, the alternate node filtering algorithm (ANF) and the adjustment factor of cost matrix are proposed in this paper to enhance the system service performance without changing the minimum total service cost, and corresponding theoretical proof has been provided. In addition, for improving the fault tolerance of system, the alternate node preference factor and algorithm (ANP) are presented, which can effectively reduce the probability of data copy loss, based on which an improved cost-efficient replica deployment strategy named ICERD is given. Finally, by simulating the random occurrence of cloud node failures in the experiments and comparing the ICERD strategy with representative strategies, it has been validated that the ICERD strategy proposed in this paper not only effectively reduces customer access latency, meets customers' QoS requests, and improves system service quality, but also maintains the load balancing of the entire system, reduces service cost, enhances system fault tolerance, which further confirm the effectiveness and reliability of the ICERD strategy.

• Journal of Power Electronics
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• 제14권6호
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• pp.1157-1165
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• 2014

The T-type topology is a three-level topology that has an advantage in terms of its number of switching device and its efficiency when compared to the neutral-point clamped (NPC)-type topology. With the recent increase in the usage of the T-type topology, the interest in its reliability has also increased. Therefore, a tolerance control for a T-type rectifier is necessary to improve the reliability of applications when an open-switch fault occurs. NPC-type rectifiers cannot eliminate input current distortion completely. However, the T-type rectifier is able to restore distorted current. In this paper, a tolerance control for the $S_{x2}$ and $S_{x3}$ open-switch faults of a T-type rectifier is proposed where it is advantageous in terms of efficiency when compared with other tolerance controls. The performance of the proposed tolerance control is verified through simulation and experimental results.

• 전기전자학회논문지
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• 제24권1호
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• pp.170-177
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• 2020

본 논문은 HF/LF 변조 방법을 적용한 ANPC (active neutral point clamped) 인버터의 스위치 개방 고장에 대응하기 위한 허용 제어 방법을 제안한다. 기존 Si 기반 인버터에 비해 SiC MOSFET과 Si IGBT로 구성된 ANPC 인버터는 시스템의 효율이 높고 출력 품질이 우수하다. HF/LF 변조는 커뮤테이션 루프를 줄일 수 있어 MW 급 대용량 인버터를 위해 사용되는 변조 기법이다. MW 급 인버터의 스위치 개방 고장은 부하에 심각한 손상을 입히며, 인버터가 동작을 멈출 경우 막대한 경제적 손실을 야기한다. 제안하는 스위치 개방 고장의 허용 제어 기술은 ANPC 인버터의 지속적인 운전을 가능하게 하며 신뢰성을 향상 시킨다. 제안하는 기법의 성능은 시뮬레이션 결과를 통해 검증한다.