• Journal of the Korean Institute of Navigation
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• v.24 no.1
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• pp.47-56
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• 2000

As a shipboard dependency for the safety and reliability becomes very important, the need for solid systems providing non-stop workload has been increased. This system is heartbeat that transmits shipboard state, audit and control information to the land. So, this paper describes a ship's LAN configuration method for the safety and reliability. In order to achieve these requirements, network, server and disk fault tolerance techniques are surveyed, and dual network configuration model, cluster server configuration method are presented and tested based on the survey.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.05a
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• pp.197-200
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• 2019

가상 화폐 분야의 핵심 기술로 소개된 블록체인(Blockcahin) 기술은 4차 산업혁명에서 중심이 되는 기술로 주목받고 있다. 본 논문에서는 블록체인 시스템의 구조도와 대표적인 합의 알고리즘, 즉 증명(PoW: Proof of Work), 지분증명(PoS: Proof of Stake) 그리고 PBFT (Practical Byzantine Fault Tolerance)을 조사하였다. 합의 알고리즘의 특성을 분석하기 위하여, 보안성, 에너지 소비량, 거래 처리속도를 지표로 세워서 합의 알고리즘들에 대하여 전체적으로 비교 및 분석을 하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.69-71
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• 2013

가상화된 서버를 관리하기 위해서 쓰이는 기술 중 하나가 바로 라이브 가상 머신 마이그레이션으로 이는 서비스를 제공하고 있는 서버의 구동 중지 시간을 줄여 이용자의 불편함을 최소로 하면서 Load balancing 및 Fault tolerance system 구성에 이득을 줄 수 있는 기술이다. 본 논문에서는 라이브 가상 머신 마이그레이션의 성능을 향상하고 한계점을 극복하기 위한 연구 주제를 살펴보고 이를 토대로 향후 연구 방향에 대해 모색하도록 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1314-1315
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• 2008

Recent research work has unearthed that multi-radio multi-channel wireless mesh networks offer considerable capacity gains over single-radio wireless mesh networks. In this paper, we present a new routing metric for multi-radio multi-channel wireless mesh networks. The goal of the metric is to choose multiple link/node disjoint paths between a source and destination node that, when used concomitantly, impart high end-to-end throughput. The proposed metric selects high fidelity paths that will produce elevated throughput with maximum fault tolerance.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.222-224
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• 2007

내고장성(fault - tolerance)을 향상시키면서 소프트웨어의 신뢰도를 최적화하는 두가지 접근법으로서 수정복구 블록 스킴과 N-버전 프로그래밍 기법이 있다. 본 연구에서는 중복모줄을 가지고 소프트웨어의 신뢰도를 극대화하기 위한 하나의 알고리즘으로서 수정복구 스킴을 제안한다. 개발소프트웨어의 최적구조를 결정하는 기법을 수립하기 위해 최적화 공정 결과를 적용한다. 주어진 가용자원 범위 내에서 정규실행모줄과 테스트모줄의 신뢰도 및 확률을 계산하여 소프트웨어 시스템의 신뢰도를 극대화하기 위한 소프트웨어의 형상을 고찰한다. 간단한 예로서 한 개의 경우를 예시한다.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.5
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• pp.512-516
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• 2008

A conference-key agreement protocol is essential for computer network conferences that need secure communications. Especially, the fault-tolerant conference-key agreement can make a shared conference-key even if some make conferees disturb the key agreement processes. However, the performance of the previous fault-tolerant conference-key agreement protocols is decreasing significantly when the number of fake conferees is increasing. In this paper, we propose an efficient fault-tolerant conference key agreement protocol. Our scheme is based on the ID-based one round tripartite conference key agreement protocol. Simulation results show our scheme's efficiency against Yi's method especially when the number of fake conferees is large.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.1
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• pp.44-54
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• 2001

In this paper, a novel test method is proposed to detect the hard and soft fault in analog circuits. The proposed test method makes use of the offset voltage, which is one of the op-amps characteristics. During the test mode, CUT is modified to unit gain op-amps with feedback loop. When the input of the op-amp is grounded, a good circuit has a small offset voltage, but a faulty circuit has a large offset voltage. Faults in the op-amp which cause the offset voltage exceeding predefined range of tolerance can be detected. In the proposed method, no test vector is required to be applied. Therefore the test vector generation problem is eliminated and the test time and cost is reduced. In this note, the validity of the proposed test method has been verified through the example of the dual slope A/D converter. The HSPICE simulations results affirm that the presented method assures a high fault coverage.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.2
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• pp.120-134
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• 2000

In this paper we present a Distributed Object oriented Virtual computing Environment, called DOVE which consists of autonomous distributed objects interacting with one another via method invocations based on a distributed object model. DOVE appears to a user logically as a single virtual computer for a set of heterogeneous hosts connected by a network as if objects in remote site reside in one virtual computer. By supporting efficient parallelism, heterogeneity, group communication, single global name service and fault-tolerance, it provides a transparent and easy-to-use programming environment for parallel applications. Efficient parallelism is supported by diverse remote method invocation, multiple method invocation for object group, multi-threaded architecture and synchronization schemes. Heterogeneity is achieved by automatic data arshalling and unmarshalling, and an easy-to-use and transparent programming environment is provided by stub and skeleton objects generated by DOVE IDL compiler, object life control and naming service of object manager. Autonomy of distributed objects, multi-layered architecture and decentralized approaches in hierarchical naming service and object management make DOVE more extensible and scalable. Also,fault tolerance is provided by fault detection in object using a timeout mechanism, and fault notification using asynchronous exception handling methods

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.7
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• pp.333-340
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• 2005

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 network-based computer system is partially compromised because of the external or internal intrusions is the quantitative dependability analysis of the ITS. In this paper, we applied self-healing mechanism, the core technology of autonomic computing to secure the protection power of the ITS. We analyzed a state transition diagram of the ITS composed of a Primary server and a backup server utilizing two factors of self-healing mechanism (fault model and system response) and calculated the availability of ITS through simulation experiments and also performed studies on two cases of vulnerability attack.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.7
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• pp.545-549
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• 2007

The Bio-Inspired System focuses on the creation of an effective system model for massive network applications and is being widely developed. However, the system has a problem-difficulty implementing three features in the system, which includes scalability, adaptability and survivability. To solve this problem, we designed an Ecogent as a multiple intelligence agent, and a Bio-platform to address the three features of scalability, adaptability and survivability. The Bio-Inspired System Platform consists of an ERS (Ecogent Runtime Services) Platform and a Bio-Platform. The ERS platform serves the basic functions of mobile agents, such as Registration, Life Cycle, Migration, Communication, Location and Fault Tolerance. The Bio-Platform includes the functions of Evolution Control and Stigmergy Control to address evolution and adaptation.