• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.187-189
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• 2003

This paper presents new service restoration algorithm to deal with multiple faults such as main transformer fault, whole substation fault and simultaneous faults. The most important consideration of restoration planning for multiple outage areas is efficient use of redundant backup feeders. The proposed algorithm tries to restore all outage loads using outage area ordering method and tie switch exchange method that are newly proposed in this paper.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.352-359
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• 2000

In this paper, the method is used that each system isolates the part in which faults are occurred in case of fault occurrence since total system is designed in the type of hot standby sparing system construction and self-checking circuit in each system is attached to the memory being of the high failure rate in common communication system. Thus reliability and availability in system are improved. In this thesis, self-checking circuit was designed using 2 out of 6 code and didn't have any effect to the system operation. For the purpose of verification, each system attached with self-checking circuit was simulated through fault injection arid the continuity of each system in hot standby sparing system was tested in case that the system was switched when faults in the system were occurred.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.2
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• pp.264-272
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• 1998

This paper proposes a fault detection and recovery mechanism for a fault-tolerant Mini-MAP system, and provides detailed techniques for its implementation. This paper considers the fault-tolerant Mini-MAP system which has dual layer structure from the LLC sublayer down to the physical layer to cope with the faults of those layers. For a good fault detection, a redundant and hierarchical fault supervision architecture is proposed and its implementation technique for a stable detection operation is provided. Information for the fault location is provided from data reported with a fault detection and obtained by an additional network diagnosis. The faults are recovered by the stand-by sparing method applied for a dual network composed of two equivalent networks. A network switch mechanism is proposed to achieve a reliable and stable network function. A fault-tolerant Mini-MAP system is implemented by applying the proposed fault detection and recovery mechanism.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.4
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• pp.1-10
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• 1998

Partitioning problem of large combinational logic has been studied in real world. Most of logic include undectable faults from the structure of it's redundant, fan-out-reconvergent, and symetrical feature. BPT algorithm is proposed to enhance the fault voverage for combinational logic partitioning. This algorithm partitions the logic by cut the lines related to undetectable structure when seperating. Controllability and observability are considered in the process of partitioning. This algorithm is evaluated effective by testing ISCAS85 circuits.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.3
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• pp.292-301
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• 2014

This paper describes development of distributed type independent electro-hydraulic ballast valve remote control system with diagnostic function based on fuzzy inference using redundant Modbus communication and ethernet Modbus TCP/IP. Diagnostic function estimate degradation of system components and diagnose system faults, which results in shortage of fault maintenance time and improvement of system safety. Slave devices which control each valve and master device which command, monitor and diagnose slave system are developed. Slave devices are connected to master device with redundant Modbus networks and master device is connected to ship's integrated control system with Modbus TCP/IP. Also this paper describes development of simulator to test and confirm whether developed system can be integrated with ship's integrated control and monitoring system.

• The Transactions of the Korea Information Processing Society
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• v.6 no.1
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• pp.216-224
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• 1999

In the paper we propose two recovery methods by adopting a rollback and/or roll-forward technique (S) to recover TMR failures in a TMR (structured ) system that is the simplest spatial redundancy. This technique is apparently effective to recovering TMR failures primarily caused by transient faults. The proposed policies carry out few reconfigurations at the cost of (minimal) time-overhead needed for those time-redundant schemes. The optimal checkpoint-interval vectors are derived for both methods through the likelihoods of all (possible) states of the system as well as the total execution-time. Consequently the effectiveness of our proposed policies is validated through certain numerical examples and simulations.

• The KIPS Transactions:PartA
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• v.13A no.5 s.102
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• pp.421-428
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• 2006

This paper proposes an integrated recovery approach applying retry and rollback techniques to recover the TMR failure. Combining the time redundancy techniques with W system is apparently effective to recover the TMR failure(or masked error) primarily caused by transient faults. These policies need fewer reconfigurations at the cost of extra time required for the time redundant schemes. The optimal numbers of retry and rollback to minimize the mean execution time of tasks are derived for the proposed method through computing the likelihoods of all possible states of the failed system. The effectiveness of the proposed method is validated through examining certain numerical examples and simulations conducted with a variety of parameters governing environmental characteristics.

• Journal of the Korean Institute of Telematics and Electronics
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• v.11 no.4
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• pp.17-22
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• 1974

In this paper, the problem of finding tests to detect faults in combinational logic circuits is considered. At first, the method of fault detection in fan-out-free irredundant circuits is derived, and the result is extended to the fan-out redundant circuits. A fan-out circuit is decomposed into a set of fan-out-free subcircuits by cutting the lines at the internal fan-out points, and the minimal detecting test. sets for each subcircuit are found separately. And then, the compatible tests from each test set are combined maximally into composite tests to generate primary input binary vectors. By this procedure. the minimal complete test sets for reconvergent fan-out circuits are easily found and the detectable and undetectable faults are also classified clearly.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.5
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• pp.1829-1846
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• 2021

Transient faults occur in computation units of a processor, which can cause control flow errors (CFEs) and compromise system reliability. The software-based methods perform illegal control flow detection by inserting redundant instructions and monitoring signature. However, the existing methods not only have drawbacks in terms of performance overhead, but also lack of configurability. We propose a configurable approach CCFCA for detecting CFEs. The configurability of CCFCA is implemented by analyzing the criticality of each region and tuning the detecting granularity. For critical regions, program blocks are divided according to space-time overhead and reliability constraints, so that protection intensity can be configured flexibly. For other regions, signature detection algorithms are only used in the first basic block and last basic block. This helps to improve the fault-tolerant efficiency of the CCFCA. At the same time, CCFCA also has the function of solving confusion and instruction self-detection. Our experimental results show that CCFCA incurs only 10.61% performance overhead on average for several C benchmark program and the average undetected error rate is only 9.29%. CCFCA has high error coverage and low overhead compared with similar algorithms. This helps to meet different cost requirements and reliability requirements.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2335-2339
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• 2003

To prevent the critical situation due to the fault in the aircraft sensor system, the fault tolerant system with triple or quadruple redundancy can be made. However, if the faults are occurred in two or more than sensors simultaneously, the conventional fault detection process, such as cross-channel monitoring, may give the wrong fault alarm. For this case, we can detect the fault by estimating the state vector based on the system dynamics model, which is nonlinear for aircraft. In this paper, we propose the unscented Kalman filter to estimate the nonlinear state vector. This filter utilizes the so-called unscented transformation of sigma points featured the statistical characteristics of the random variable. For verification, we perform the simulations for F-16 aircraft with accelerometers, gyros, GPS and air data system.