• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.6
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• pp.735-746
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• 1999

We design the robust and inherently fault tolerant decetralized$$H^infty$$ filter for the multisensor state estimation problem when there are insufficient priori informations on the statistical properties of external disturbances. For developing the proposed algorithm, an alternative form of suboptimal$$H^infty$$ filter equations are formulated by applying an alternative form of Kalman filter equations to the indefinite inner product space state model of suboptimal$$H^infty$$ filtering problems. The decentralized$$H^infty$$ filter that consists of local and central fusion filters can be designed effciently using the proposed alternative$$H^infty$$ filiter gain equations. The proposed decentralized$$H^infty$$ filter is robust against un-known external disturbances since it bounds the maximum energy gain from the external disturbances to the estimation errors under the prescribed level$$r^2$$ in both local and central fusion filters and is also fault tolerant due to its inherent redundancy. In addition, the central fusion equations between the global and local data can reduce the unnecessary calculation burden effectively. Computer simulations are made to ceritfy the robustness and fault tolerance of the proposed algorithm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1333-1341
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• 2010

The goal of this research is to enhance the maintenance and monitoring system of ship environment using sensor network. It is important to know the location information of sensor nodes to control the sensors and to obtain the sensor data from sensor network inside the ship. In this paper, we address the grouping and routing mechanism according to the relative distance of sensor nodes, based on LEACH and PEGASIS. We also consider the fault tolerant mechanism using the location information of sensor nodes.

• Proceedings of the Korea Contents Association Conference
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• 2005.05a
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• pp.315-319
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• 2005

In this paper, we present a Petri Net (PN) model for reliability analysis of fault-tolerant database system models that consists of components one shared memory, bus, processors and database (disk). Each component can be failed and repaired individually. The system is operational as long as database and one of component is operational. We develop Stochastic Reward Net (SRN) Model for reliability analysis of database system. SRN is potential to define various reward functions. and can be easily used to obtain performance measures. The modeling techniques using variable cardinality, enabling function, timed transition priority in SRN are shown.

• Journal of the Korea Society of Computer and Information
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• v.19 no.5
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• pp.1-10
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• 2014

The proposed scheme schedules given real-time tasks so that energy consumption of multicore processors would be minimized while meeting tasks' deadline and tolerating a permanent fault based on the primary-backup task model. Whereas the previous methods minimize the overlapped time of a primary task and its backup task, the proposed scheme maximizes the overlapped time so as to decrease the core speed as much as possible. It is analytically verified that the proposed scheme minimizes the energy consumption. Also, the proposed scheme saves up to 77% energy consumption of the previous method through experimental performance evaluation.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.293-295
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• 2004

The Engineering Model of on-board computer was developed and tested completely with other sub-systems for STSAT-2. We designed the on-board computer of STSAT-2 which has some improved features compared with that of STSAT-l. A remarkable change is that the on-board computer has a structure of centeralized network communication without a Network Controller of the STSAT-l. That is, the on-board computer directly manages a satellite network. In addition, as many logics are implemented by Field Programmable Gate Array, so we can reduce the weight and size of on-board computer. Also, the developed on-board computer has more improved tolerance against Single Event Upsets and faults than that of the STSAT-l.

• ETRI Journal
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• v.30 no.6
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• pp.856-858
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• 2008

Odd networks were introduced in the context of graph theory. However, their potential as fault-tolerant multiprocessor networks has been shown. Broadcasting is one of the most important communication primitives used in multiprocessor networks. In this letter, we introduce efficient one-to-all broadcasting schemes of odd networks for one-port and all-port models. We show the broadcasting time of the former is 2d-2 and that of the latter is d-1. The total time steps taken by the proposed algorithms are optimal.

• 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.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1999-2005
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• 2005

Collaboration in wireless sensor networks must be fault-tolerant due to the harsh environmental conditions in which such networks can be deployed. This paper focuses on finding signal processing algorithms for collaborative target detection based on the generalized approach to signal processing in the presence of noise that are efficient in terms of communication cost, precision, accuracy, and number of faulty sensors tolerable in the wireless sensor network. Two algorithms, namely, value fusion and decision fusion constructed according to the generalized approach to signal processing in the presence of noise, are identified first. When comparing their performance and communication overhead, decision fusion is found to become superior to value fusion as the ratio of faulty sensors to fault free sensors increases. The use of the generalized approach to signal processing in the presence of noise under designing value and decision fusion algorithms in wireless sensor networks allows us to obtain the same performance, but at low values of signal energy, as under the employment of universally adopted signal processing algorithms widely used in practice.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.331-334
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• 2006

This paper deals with the ways how the AUV is composed of sub-modules to be fault-tolerant during the mission. The emergency situations can be classified into several parts according to the zones where the situations take place - sensor zone, actuator zone, interpreter zone, and communication zone. This paper explains how each element of emergency situation is detected, contained and treated, and as a result, introduce the modular structured AUV controller for the autonomous cruising.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.3_4
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• pp.204-212
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• 2004

Existing distributed systems have higher probability of failures occurrence than stand-alone system, so many fault tolerant techniques have been developed. Because of insufficient storage resulting from the increased fault tolerance information stored, the performance of system has been degraded. To avoid performance degradation, it needs delete useless fault tolerance information. In this paper, we propose a garbage collection algorithm for fault tolerance information. And we define and design the garbage collection agent for garbage collection of fault tolerance information, the information agent for management of fault tolerant data, and the facilitator agent for communication between agents. Also, we propose the garbage collection algorithm using the garbage collection agent. For rollback recovery, we use independent checkpointing protocol and sender based pessimistic message logging protocol. In our proposed garbage collection algorithm, the garbage collection, information, and facilitator agent is created with process, and the information agent constructs domain knowledge with its checkpoints and non-determistic events. And the garbage collection agent decides garbage collection time, and it deletes useless fault tolerance information in cooperation with the information and facilitator agent. For propriety of proposed garbage collection technique using agents, we compare domain knowledge of system that performs garbage collection after rollback recovery and domain knowledge of system that doesn't perform garbage collection.