• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.06a
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• pp.298-303
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• 2011

최근 한반도의 잇따른 북한의 Jamming(교란신호)으로 인해 무선통신 기반 산업에 피해사례가 늘고 있다. 이에 국토해양부(위성항법중앙사무소)에서 운영중인 위성항법보정시스템(이하 "DGPS") 데이터 분석하였다. 그 결과 2010년도 발생한 재밍과 달리 2011년도에는 DGPS 기준국/감시국에서는 감지가 되지 않은 것으로 분석 되었으나, 피해 현황을 조사하여 이를 토대로 범국가적 대책방안(항행 백업시스템 개발, 유관기관과의 정보공유를 통한 감지 통합시스템 구축) 및 DGPS 운영 효율성 확보방안(감시국 신설, 실시간 감시프로그램 강화 등)에 대하여 제안하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.1
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• pp.58-68
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• 2010

In this paper, we propose an efficient link protection switching scheme for provider backbone bridge systems with a spanning tree for backup links exclusively, and evaluate its performance. The proposed scheme offers guaranteed QoS flows even when a link fault occurrs in the primary link by flooding the flows over the profiled spanning tree. The flooding mechanism over the spanning tree can also provide low latency and remove the loopback flows. We also derive the efficiency of bandwidth usage for the normal flows and the number of lost frames during the link restoration. For evaluating its feasibility, we implement a prototype of PBB-TE systems based on the Linux bridge codes, which can support both link protection switching capability with CCM and MAC-in-MAC encapsulation. A related protocol analyzer is also developed. One can see that the proposed scheme and the prototype can be useful for developing carrier class Ethernet systems based on PBB-TE.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.10
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• pp.2323-2330
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• 2014

Most organizations are more depending on information system in advanced information society. According to this current, unrapid reaction to system failure can cause a fatal effect to a credibility of the organization. An excessively high level of dependence on information system at work makes itself as a primary target of cyber terror. The stability of university's information system is especially weaker than the enterprise's but policy support for securing availability is inadequate. In this paper, we consider the recovery system toward to disorder of university's school affairs information system theoretically and suggest high availability PC based academic administration system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.2040-2048
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• 2010

In contemporary society, though convenience and efficiency of work using information system is growing high, adverse effect problems of malignant code, system hacking, information leak by insiders due to the development of the network are raising their head daily. Because of this, enormous work forces and expenses for the recovery and management of system is needed. The existing system can be divided into two aspects: security solution which surveils and treats virus and malignant codes, and network management solution which observes the system of computer, and practices maintenance and repair such as management, recovery, backup. This treatise applied Active Write Filter mechanism and the technology based on NFS and complemented the maintenance problems of user data of the existing system and designed the system which enables solving problems of intellectual property right such as information protection and illegal work.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.9
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• pp.75-81
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• 2008

The effect of the fault could be propagated to healthy region when the fault on the power system is not cleared in time. In order to enhance reliability of the protective relay, a dual and/or backup system is adopted for the power system protection. The IEC61850 has become an international standard of the substation automation system for interoperability between heterogeneous IEDs from different vendors. This paper introduces a reliability enhancement technique for the substation automation system using characteristics of the IEC61850.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12B
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• pp.1022-1036
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• 2004

In mobile cellular network the ever-changing location of a mobile host necessitates the continuous tracking of its current position and efficient management of location information. A database called Home Location Register(HLR) plays a major role in location management in this distributed environment, providing table management, index management, and backup management facilities. The objectives of this paper are to identify the p개blems of the current HLR system through rigorous analysis, to suggest solutions to them, and to propose a new architecture for the HLR system. In the HLR system, a main memory database system is used to provide real-time accesses and updates of subscriber's information. Thus it is suggested that the improvement bemade to support better real-time facilities, to manage subscriber's information more reliably, and to accommodate more subscribers. In this paper, I propose an efficient backup method that takes into account the characteristics of HLR database transactions. The retrieval speed and the memory usage of the two-level index method are better than those of the T-tree index method. Insertion md deletion overhead of the chained bucket hashing method is less than that of modified linear hashing method. In the proposed backup method, I use two kinds of dirty flags in order to solve the performance degradation problem caused by frequent registration-location operations. Performance analysis has been performed to evaluate the proposed techniques based on a system with subscribers. The results show that, in comparison with the current techniques, the memory requirement is reduced by more than 62%,directory operations, and backup operation by more than 80%.

• Review of KIISC
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• v.9 no.1
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• pp.87-100
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• 1999

범국가적으로 추진되고 있는 정보화 사업은 행정 분야에서도 활발히 추진되고 있다. 본 고에서는 정보시스템의 재해복구를 위한 대체처리시설의 확보전략과 데이터의 백업 방법에 대하여 살펴보고, 대민업무에 직접적으로 활용되고 있는 광역지방자치단체의 행정전산망을 대상으로 각종 재해에 대비한 정보시스템 비상계획의 현황을 살펴보고 가용성을 확보하기 위한 효과적인 방안을 제시하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.1745-1748
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• 2005

클러스터 기반 웹 시스템에서 클라이언트의 계층별 요청 형태에 따라 차별화된 서비스를 제공하려는 시도가 활발하다. 서비스 제공자와 클라이언트간의 서비스 계약 조건(SLA: Service Level Agreement)을 만족시키기 위해, 웹 스위치 단계에서 클라이언트의 서비스 요청의 내용을 파악한 후 동적으로 서버에 요청처리 작업을 할당함으로써, 클라이언트 계층별 SLA 의 제공이 가능하다. 하지만, 모든 클라이언트의 요청은 웹 스위치를 통하여 각 서버에 분배되기 때문에, 웹 스위치가 내부적 결함이나 외부의 침입에 의해 정상적인 서비스를 제공하지 못하는 경우, 웹 시스템 서비스의 다운을 초래 할 가능성이 높다. 본 논문에서는, 웹 스위치의 내부적인 결함은 물론 외부의 악의적인 공격(예, 침입, 바이러스)으로 인하여 웹 스위치에 문제가 발생하는 경우 대기하고 있는 백업(backup) 웹 스위치로 대치하여 서비스를 계속 수행함으로써, SLA 가 고려된 웹 시스템의 가용도(Availability)를 높일 수 있는 구조를 제안하였고, 마코브(Marcov) 분석 및 실험을 통해 시스템 가용도와 SLA 척도를 정량적으로 평가하였다.

• Journal of IKEEE
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• v.23 no.2
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• pp.580-585
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• 2019

Batteries are being used in ESS, electric vehicles and uninterruptible power backup systems. Lead-acid batteries are the most used batteries for high capacity power back up equipment due to their high reliability and low price advantages. It is very important to estimate the chargeable capacity(SoH), and many algorithms were proposed to estimate the internal resistance of the battery. In this paper, the Battery Monitoring System(BMS) for high capacity uninterruptible power supply for IDC is proposed. A simple algorithm for estimating internal resistance was proposed. An computational block diagram of the proposed signal processing algorithm and BMS system configuration of CPU and analog circuit were shown. The proposed method was proved useful by presenting data examples of application to actual IDC sites.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.141-143
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• 2014

전자해도시스템은 2012년 7월 1일 부로 국제항해에 종사하는 선박에 단계별로 설치가 강제화 되었다. 전자해도시스템은 백업장치를 갖춘다면 종이해도를 대체하여 사용할 수 있는 설비로 선교에서 사용의존도가 높은 핵심항해설비라고 할 수 있다. 현재 전자해도 시스템 이용 시 전 세계적으로 다양한 오류가 발생하고 있으며, 국제해사기구에서도 문제를 인식하고 오류해결을 위한 방안을 모색하고 있는 중이다. 본 논문에서는 사용자들을 대상으로 전자해도시스템의 기능 이용 시의 오류 및 문제점에 대한 사항을 설문을 통해 조사 분석하고 기능에 대한 개선사항에 대하여 연구하였다.