• Journal of Advanced Navigation Technology
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• v.21 no.5
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• pp.491-500
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• 2017

This paper investigates a low cost dual modular redundancy system based on heartbeat which can be applied to traffic control signal system. Failure of the traffic control signal system can cause traffic confusion and traffic accidents. Therefore safety and reliability of traffic control should be secured using fault tolerance technology. To do this, we configured a redundant board using the open source hardware and the heartbeat technique of Linux HA. The function of the traffic signal control system was verified and the fault recovery time was measured using fault injection test. As a result of the test, the fault recovery time was confirmed to be less than 9 seconds on average, confirming that the reliability target time is satisfied. Based on the results of this study, it is expected that it can be applied to fields requiring high reliability systems such as aviation, space, and nuclear power embedded systems.

• The KIPS Transactions:PartA
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• v.15A no.3
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• pp.151-154
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• 2008

A middleware in grid computing environment is required to support seamless on-demand services over diverse resource situations in order to meet various user requirements [1]. Since grid computing applications need situation-aware middleware services in this environment. In this paper, we propose a semantic middleware architecture to support dynamic software component reconfiguration based fault and service ontology to provide fault-tolerance in a grid computing environment. Our middleware includes autonomic management to detect faults, analyze causes of them, and plan semantically meaningful strategies to recover from the failure using pre-defined fault and service ontology trees. We implemented a referenced prototype, Web-service based Application Execution Environment(Wapee), as a proof-of-concept, and showed the efficiency in runtime recovery.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.10
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• pp.553-561
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• 2004

Leader election is an important problem in developing fault-tolerant distributed systems. As a classic solution for leader election, there is Garcia-Molina's Bully Algorithm based on time-outs in synchronous systems. In this paper, we re-write the Bully Algorithm to use a failure detector instead of explicit time-outs. We show that this algorithm is more efficient than the Garcia-Molina's one in terms of the processing time. That is because the Bully_FD uses FD to know whether the process is up or down so fast and it speed up its execution time. Especially, where many processes are connected in the system and crash and recovery of processes are frequent, the Bully_FD algorithm is much more efficient than the classical Bully algorithm in terms of the processing time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1889-1896
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• 2011

There has been a lot of researches to develop techniques that provide redundant paths, there by making Multistage Interconnection Networks(MINs) fault tolerant. So far, the redundant paths in MINs have been realized by adding additional hardware such as extra stages or duplicated data links. This paper presents a new MIN topology called Hierarchical MIN. The proposed MIN is constructed with 2.5N-4 switching elements, which are much fewer than that of the classical MINs. Even though there are fewer hardware than the classical MINs, the HMIN possesses the property of full access and also provides alternative paths for the fault tolerant. Furthermore, since there is the short cut in HMIN for the localized communication, it takes advantage of exploiting the locality of reference in multiprocessor systems. Its performance under varying degrees of localized communication is analysed and simulated.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.182-184
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• 2009

FlexRay is a new standard of network communication system which provides a high speed serial communication, time triggered bus and fault tolerant communication between electronic devices for future automotive and ship applications. FlexRay communication controller(CC) is the core of the FlexRay protocol specification. In this paper, we first design the FlexRay CC protocol specification and function parts using SDL(Specification and Description Language). Then, the system is re-designed using Verilog HDL based on the SDL source. The FlexRay CC system was synthesized using Samsung $0.35{\mu}m$ technology. It is shown that the designed system can operate in the frequency range above 80 MHz. In addition, to show the validity of the designed FlexRay system, the FlexRay system is combined with sound source localization system in Robot applications. The combined system is implemented using ALTERA Excalibur ARM EPXA4F672C3. It is shown that the implemented system operates successfully.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04a
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• pp.381-384
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• 2002

This paper describes the motivation, design and performance of bi-active Load balancer in Linux Virtual Server. The goal of bi-active Load balancer is to provide a framework to build highly scalable, fault-tolerant services using a large cluster of commodity servers. The TCP/IP stack of Linux Kernel is extended to support three IP load balancing techniques, which can make parallel services of different kinds of server clusters to appear as a service on a single IP address. Scalability is achieved by transparently adding or removing a node in the cluster. and high availability is provided by detecting node or daemon failures and reconfiguring the system appropriately. Extensive simulation reveals that the proposed approach improves the reply rate about 20% compared to earlier design.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.467-474
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• 1999

In this paper, Fault tolerant digital governor, using duplex I/O module and triplex CPU module and also 2 out of 3 voting algorithm and adding self diagnostic ability, is designed to realize ceaseless controlling and to improve the reliability of control system. The processor module of the system(SIDG-3000) is developed based on MC68EC040 32 Bit of Motorola, which guaranteed high quality of the module ,and SRAM for data also SRAM for command are separated. The process module also includes inter process communication function and power back up function (SRAM for back-up). System reliability is estimated by using the model of Markov process. The reliability of triplex system in mission time can be improved about 1.8 times in reliability 86%. 2.8 times in 95 %, 6 times in 99 % compared with a single control system. Designed digital governor system is applied after modelling of the steam turbine generator system of Buk-Cheju Thermal Power Plant. Simulation is carried out to prove the effectiveness of the designed digital governor system

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.11
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• pp.999-1005
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• 2007

In case of an abnormal condition of control surface, the real-time estimation of aerodynamic derivatives are required for the reconfigurable control system to be flight for missions or return to the head office. The goal of this paper is to represent a technique of fault detection to the control surface as a base research to the fault tolerant control system for safety improvement of UAV. The real-time system identification for the fault detection to the control surface was applied with the recursive Fourier Transform and verified through the HILS and flight test. The failures of the control surface are detected by comparing the control derivatives in fault condition with the normal condition. As a result from the flight test, we have confirmed that the control derivatives of fault condition less than about 50% in the normal condition.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.644-647
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• 2007

많은 수의 CPU를 사용해 오랜 시간 계산하는 초대형 연산의 경우, 일부 노드나 통신회선의 장애로 연산 실패를 종종 겪는데, 이를 위해 응용 수준의 무정지 연산 시스템의 구현이 중요하다. 본 논문에서는 비동기 알고리즘을 사용한 이전 시스템의 약점을 보완하여, 동기 알고리즘에도 적용가능한 새로운 응용수준의 무정지 연산 시스템을 제안하고 선형시스템의 해법에 적용하였다.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.6-10
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• 2003

The reliability of power electronics system is very important In industrial, commercial and military applications. This paper presents the principles for NPC inverter as an available technology for the design and implementation of adaptive fault tolerant systems. The fault tolerance is obtained by the use of the particular construction. The control method is proposed to get the sinusoidal load current with constant amplitude. The strategy described in this paper is expected to provide an economic alternative to more expensive redundancy techniques which find justification only in a few specialized application.