• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1853-1856
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• 2003

This paper considers the problem of longitudinal control of a platoon of automotive vehicles on a straight lane of a highway and proposes control laws in the event of loss of communication between the lead vehicle and the other vehicles in the platoon. Since safety plays a key role in the development of an Automated Highway System, fault-tolerant control is vital. In this paper, we develop a control algorithm in vehicle platooning and prove that this control algorithm is stable for certain class of faults such as parameter uncertainties. The performance of the controller is demonstrated through a series of simulations incorporating various vehicles and AHS faults. Results of simulation shows that the vehicles have good performance in spite of simple automotive and AHS failure, such as actuator failure,that is to say, engine input failure, communication failure between lead vehicle and the another vehicles.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.12
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• pp.778-788
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• 2000

Chopper and sensors failures resulting from electric shock and mechanical vibration generated by rail irregularities are the serious problem deteriorating the performance in the electromagnetic suspension systems. Thus, this paper proposes a fault-tolerant control scheme with a dynamic compensator for the failure of the choppers, gap sensors and acceleration sensors in electromagnetic suspension system. The advantage of the proposed control method are demonstrated through simulation and experimental results for the levitation characteristics when the failures of the chopper and sensors occur, respectively.

• Electronics and Telecommunications Trends
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• v.37 no.2
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• pp.1-10
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• 2022

Similar to present computers, quantum computers comprise quantum bits (qubits) and an operating system. However, because the quantum states are fragile, we need to correct quantum errors using entangled physical qubits with quantum error correction (QEC) codes. The combination of entangled physical qubits with a QEC protocol and its computational model are called a logical qubit and fault-tolerant quantum computation, respectively. Thus, QEC is the heart of fault-tolerant quantum computing and overcomes the limitations of noisy intermediate-scale quantum computing. Therefore, in this study, we briefly survey the status of QEC codes and the physical implementation of logical qubit over various qubit technologies. In summary, we emphasize 1) the error threshold value of a quantum system depends on the configurations and 2) therefore, we cannot set only any specific theoretical and/or physical experiment suggestion.

• Journal of the Korea Society of Computer and Information
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• v.10 no.4 s.36
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• pp.149-154
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• 2005

Computer center of university or company manages many non fault-tolerant servers and network devices to spare expenses. Because a service fault occurs sometimes by worm virus, system bug etc, we need a technique to detect it for continuing service. This paper introduces design and implementation of the system to observe many heterogeneous services, and web-based interface improving convenience of system manager. A system fault is reported to system managers via email or SMS by introduced service observation system, not service user. Then system managers can recover the system fault by this notification and minimize a fault period.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.7
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• pp.587-591
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• 2013

This paper addresses the robust fault tolerant controller design problems of static output systems with disturbance. The fault is expressed by the abrupt chattering of system parameters. The design conditions are derived in terms of linear matrix inequalities and linear matrix equalities. An illustrative example is provided to verify performances of the proposed controller.

• International Journal of Contents
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• v.8 no.4
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• pp.1-6
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• 2012

Mutual Exclusion is one of the most studied topics in distributed systems where processes communicate by asynchronous message passing. It is often necessary for multiple processes at different sites to access a shared resource or data called a critical section (CS) in distributed systems. A number of algorithms have been proposed to solve the mutual exclusion problem in distributed systems. In this paper, we propose the new algorithm which is modified from Garg's algorithm[1] thus works properly in a fault-tolerant system. In our algorithm, after electing the token generator, the elected process generates a new token based on the information of the myreqlist which is kept by every process and the reqdone which is received during election. Consequently, proposed algorithm tolerates any number of process failures and also does even when only one process is alive.

• ETRI Journal
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• v.33 no.1
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• pp.50-59
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• 2011

In the current very deep submicron technology era, fault tolerant mechanisms perform an essential function to cope with the effects of soft errors. To evaluate the effectiveness of the fault tolerant mechanism, reliability engineers use simulated fault injections using either saboteur modules or mutants in the simulation model. However, the two methods suffer from both inefficiency in the simulation mechanism and difficulties with the experimental setups. To overcome these inefficiencies, we propose the Verilog-based simulated fault injection (VFI) technique. VFI has the following advantages. First, modification of the design model is unnecessary. Second, the fault injection simulation procedure is simple and efficient. Third, various types of fault injection experiments can be performed. To evaluate the effectiveness of the proposed methodology, we developed a VFI environment using the ICARUS Verilog Simulator. From the experimental results, we were able to qualitatively evaluate the reliability of the target simulation models and to assess the effectiveness of the employed fault-tolerance mechanisms.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.9
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• pp.46-53
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• 2007

The link-fault recovery in the normal Ethernet bridged networks has relied on the Spanning Tree Protocol(STP) or Rapid STP. However, STP can not offer fast error recovery which is needed real-time services such as aircraft. In this paper, we compare automatic protection switching(APS) providing fault-tolerant function in the BcN back bone system with Avionic Full Duplex Switched Ethernet(AFDX) which is recently equipped in the A380 for Airbone Databuses. Also, we propose a link-bypass scheme for improving fault-tolerant performance of the AFDX by connecting switches and bypass fault section when a fault is originated on the link. For comparing and verifying the performance of proposed scheme, we simulated Ethernet, AFDX, APS and proposed AFDX with link-bypass scheme using NS-2. The proposed AFDX with link-bypass scheme can be applied to aircrafts, BcN backbone networks and industrial automatic networks.

• The Transactions of the Korea Information Processing Society
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• v.5 no.12
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• pp.3088-3098
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• 1998

The arrangement graph, which is a viable interconnection scheme for parallel and distributed systems, has been proposed as an attactive altemative to the n-cube. However, A fault tolerant design model which is well suitable for the arrangement graph doesn't has been proposd until recently, but fault tolerant design modelsfor many schemes have been proposed ina large number of paper. So, our paper presents a new fault tolerant design technique suited for the arrangement graph. To maintains the previous structures when it ocurs a fault in the current processing, the scheme properly sugbstitutes a fault-componnent into the existing structures by adding a spare component. the first of all, it converts arrangement graph into a circulant graph using the hamiltonian property and then uses automorphism of circulant graph to tolerate faults. Also, We optimize the cost of rate fault tolerant architectures by adding exactly k spare processor while tolerating up to k processor and minimizing the maximum number of limks per processor. Specially, we proposes a new techniue to minimize the maximum number of links.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12B
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• pp.1044-1048
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• 2006

This paper proposes a FTOG(Fault-Tolerant Object Group)-based recovery services through replicated objects. In the distributed system, the fault of the object component may cause an entire system failure, evidently raising the service breakdowns. Therefore, this paper proposes recovery services with the replicated objects in case of fault occurrences. Moreover, applying the FTOG model to a virtual home network simulation, we verify the consistency maintenance and the service reliability of the proposed model.