• The KIPS Transactions:PartA
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• v.12A no.5 s.95
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• pp.395-404
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• 2005

There have been large concerns about survivability defined as the capability of a system to perform a mission-critical role, in a timely manner, in the presence of attacks, failures. In particular, One of the most important core technologies required for the design of the ITS(Intrusion Tolerance System) that performs continuously minimal essential services even when the computer system is partially compromised because of intrusions is the survivability one of In included the dependability analysis of a reliability and availability etc. quantitative dependability analysis of the In. In this Paper, we applied self-healing mechanism utilizing two factors of self-healing mechanism (fault model and system response), the core technology of autonomic computing to secure the protection power of the ITS and consisted of a state transition diagram of the ITS composed of a primary server and a backup server. We also defined the survivability, availability, and downtime cost of the ITS, and then performed studies on simulation experiments and two cases of vulnerability attack. Simulation results show that intrusion tolerance capability at the initial state is more important than coping capability at the attack state in terms of the dependability enhancement.

• Proceedings of the Korea Contents Association Conference
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• 2004.11a
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• pp.437-441
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• 2004

As the development of networks and computer systems, users want various services. To meet user's various needs, new technologies is developed and a software streaming technology, uses software with streaming technology, is newly coming out. If network trouble occurs, the software is not available because the streaming server can't send the binary code that software needs to be executed in the streaming service based on network environment. In this paper, we propose the management technology of software binary code in client that managing the binary codes classfied by the function kept in the local storage device, provides the service continuously after the network trouble with the given binary code previously not the binary code from the server.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.12
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• pp.665-679
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• 2002

The fault diameter of a graph G is the maximum of lengths of the shortest paths between all two vertices when there are $\chi$(G) - 1 or less faulty vertices, where $\chi$(G) is connectivity of G. In this paper, we analyze the fault diameter of recursive circulant $G(2^m,2^k)$ with $k{\geq}3$. Let $ dia_{m.k}$ denote the diameter of $G(2^m,2^k)$. We show that if $2{\leq}m,2{\leq}k, the fault diameter of $G(2{\leq}m,2{\leq}k)$ is equal to $2^m-2$, and if m=k+1, it is equal to $2^k-1$. It is also shown that for m>k+1, the fault diameter is equal to di a_$m{\neq}1$(mod 2k); otherwise, it is less than or equal to$dia_{m.k+2}$.

• ETRI Journal
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• v.8 no.2
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• pp.83-91
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• 1986

컴퓨터의 많은 응용에 따라 분산처리, 실시간처리, 고장감내처리 등에 대해 운영체계의 연구가 많이 되어왔다. 본고는 한국형 전전자교환기인 TDX-1 시스팀에서 사용된 TDXOS의 실현과 그 특성에 관해 서술하였다. TDXOS는 고실시간처리(Hard real time processing)와 분산처리, 컴퓨터의 이중화, 과부하제어, 실시간 디버거(Debugger) 들을 실현하였으며 뱅크(Bank)시스팀 형태의 메모리 관리기법이 사용되었다. 특히, 소형 마이크로프로세서(Z80) 및 어셈블리 언어에 최적의 동작 환경을 제공하도록 설계되어 실시간의 효율이 최대화되었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.599-601
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• 2011

무선 센서 네트워크를 구성하는 센서노드들이 클러스터를 구성하고 선출된 클러스터 헤드가 클러스터 내의 센서노드들로부터 데이터를 받아서 병합한 다음, 기지국으로 데이터를 전달하는 클러스터 기반 라우팅 방법이 연구되어 왔다. 이 클러스터 기반 라우팅 방법에서 클러스터 헤드에 고장이 발생한다면, 해당 클러스터의 데이터는 기지국으로 전달할 수 없어 데이터 신뢰성에 문제가 생긴다. 이러한 문제를 해결하기 위해, 본 논문에서는 고장감내를 지원하는 클러스터 기반 라우팅 방법을 제안한다. 제안한 방법은 각 클러스터마다 백업 클러스터 헤드를 지정하여 원래의 클러스터 헤드에 고장이 발생한다면 백업 클러스터 헤드가 그 역할을 대신하도록 함으로써 데이터 전달의 신뢰성을 보장한다.

• Journal of KIISE
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• v.44 no.5
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• pp.460-468
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• 2017

In a real-time cloud environment, the data analysis framework plays a pivotal role. Spark Streaming meets most real-time requirements among existing frameworks. However, the framework does not meet the second scale real-time fault recovery requirement. Spark Streaming fault recovery time increases in proportion to the transformation history length called lineage. This is because it recovers the last state data based on the cumulative lineage recorded during normal operation. Therefore, fault recovery time is not bounded within a limited time. In addition, it is impossible to achieve a second-scale fault recovery time because it costs tens of seconds to read initial state data from fault-tolerant storage. In this paper, we propose two techniques to solve the problems mentioned above. We apply the proposed techniques to Spark Streaming 1.6.2. Experimental results show that the fault recovery time is bounded and the average fault recovery time is reduced by up to 41.57%.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.168-171
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• 1999

A fault-tolerant system should have a high availability and high reliability to maintain a given system stable against sudden faults in the system. In this paper, we propose a new types of fault tolerant system based on a fault detection bus. The fault detection bus is designed and implemented to detect any errors by comparing event-output signals from two processor modules. It employs the hot standby sparing fault detection method〔1〕 to provide continuity of services even if a system fault occurs. The prototype fault tolerant system is currently being implemented on a management system with two processor modules.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.3
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• pp.382-391
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• 2019

The naval combat system is a distributed system in which various subsystems are integrated and operated together. The integrated management system(IMS) is a software system for systematically and consistently managing the application software which control and operate various devices in such a combat system. Since the malfunction or failure of such an IMS can disable the entire combat system, the IMS is more important than other application software of the combat system. In this paper, we propose a method to guarantee the stable and correct operation of the combat system. To this end, we propose a redundancy scheme composed of one leader and several followers so as to tolerate the failure situation of the IMS. We also propose a leader selection algorithm to select a new leader when the leader fails and can no longer perform its role. To verify the validity of the study, we verify the fault tolerance behavior of the system and the accuracy of the leader selection algorithm.

• 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.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.8
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• pp.780-785
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• 2010

The OPRoS (Open Platform for Robotic Services) framework is proposed as an application runtime environment for service robot systems. For the successful deployment of the OPRoS framework, fault tolerance support is crucial on top of its basic functionalities of lifecycle, thread and connection management. In the previous work [1] on OPRoS fault tolerance supports, we presented a framework-based fault tolerance architecture. In this paper, we extend the architecture with component-based fault tolerance techniques, which can provide more simplicity and efficiency than the pure framework-based approach. This argument is especially true for fault detection, since most faults and failure can be defined when the system cannot meet the requirement of the application functions. Specifically, the paper applies two widely-used fault detection techniques to the OPRoS framework: 'bridge component' and 'process model' component techniques for fault detection. The application details and performance of the proposed techniques are demonstrated by the same application scenario in [1]. The combination of component-based techniques with the framework-based architecture would improve the reliability of robot systems using the OPRoS framework.