• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.595-597
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• 2005

현재 IP 멀티캐스트의 도입의 지연으로, 기존의 유니캐스트 망 기반 멀티캐스트의 필요성이 대두되어 오버레이(Overlay) 멀티캐스트 관련 연구가 진행 중이다. 특히, 확장성 제공과 작은 오버헤드 등으로 효율적인 CBT(Core Based Trees) 기반의 오버레이 멀티캐스트에 대한 연구가 활발히 진행 중이다. 그러나 기존의 거리 매트릭(Metric) 기반의 CBT로 오버레이 트리를 구성하는 경우, 특정 라우터에 패킷이 집중되는 현상으로 인하여 혼잡이 발생하여 멀티캐스트 성능 저하뿐만 아니라 네트워크 전체 성능을 저하시킬 수 있다. 본 논문에서는 이를 해결칠기 위하여. 코어 노드를 기준으로 이웃하는 두 노드 간의 패킷 중계 방향성을 계산하는 알고리즘을 제안하고. 이 결과값을 이용하는 새로운 매트릭 기반의 CBT를 구성하고자 한다. 실험 결과, CBT 상의 자식 위치에 있는 종단 노드로 패킷을 중계하는 과정에서 중복되는 패킷 전송 경로를 최소화하여 CBT를 구성함으로써 특정 라우터에 집중되는 트래픽을 줄이거나 다른 라우터로 트래픽을 분산함으로써 혼잡 발생 가능을 낮추어 보다 안정적인 통신을 기대할 수 있다.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.715-717
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• 2012

최근 대용량 모바일 트래픽을 효율적으로 처리하고 다양한 5세대 지식 서비스를 제공할 수 있는 차세대 이동통신 기술개발을 목표로 중추 네트워크라는 개념이 고려되고 있다. 중추 네트워크에서는 시스템 용량을 기존 이동통신 시스템 대비 크게 증대시키기 위하여 밀리미터파 대역에서 넓은 대역폭을 사용하고 빔형성 기술을 통하여 무선자원을 재사용한다. 그러나 밀리미터파 대역은 직진성이 매우 강하기 때문에 비가시거리 통신영역에서 통신 품질이 급격히 저하되는 문제점이 발생하며, 이를 해결하기 위해 중추 네트워크에서는 적절한 위치에 중계기를 설치하여 비가시거리 통신영역을 최소화하는 것을 고려한다. 본 연구에서는 기지국 및 중계기 위치에 따른 중추 네트워크의 성능을 분석하기 위해 개발된 시스템 레벨 시뮬레이터를 소개한다. 본 시뮬레이터는 중추 네트워크의 통신영역과 채널용량을 분석 및 연구하는데 크게 기여할 수 있을 것으로 기대된다.

• ETRI Journal
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• v.14 no.3
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• pp.1-15
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• 1992

Stand-slone 신호 중계 교환기인 SMX-1(Signalling Message eXchange No.1)은 통신망의 신경계인 공통선 신호망(Common Channel Signalling Network)의 하부 구조를 구성하는 시스팀이다. SMX-1에 총괄명 번역서비스를 수용하게 되면 통신망 사용자에게 통신망 내부의 구성 및 구성 요소의 변화에 구속되지 않고 지속적인 지능망 서비스를 제공할 수 있게 된다. 본 연구에서는 SMX-1의 설계 이념에 부합되도록 신호연결 제어부의 기능을 소프트웨어 및 하드웨어적으로 분산화하여 설계, 구현함으로써 SMX-1의 고신뢰성 및 신속성을 추구하였다. 소프트웨어적으로는 총괄명번역 서비스 제공을 위해 국제 전신 전화 자문 회의(CCITT)권고 Q.711-Q.714에서 정의하고 있는 신호연결 제어부(SCCP:Signalling Connection Control Part)의 기능을 관리 기능(SCMG : SCCP Management Part)과 루팅 제어 기능(SCRC : SCCP Routing Control Part)으로 분리하여 각각의 기능을 이중화하여 설계, 구현하였다. 하드웨어적으로는 관리 기능을 하나의 보드로 집중화하고 루팅 제어 기능을 여러개의 보드로 분산화하였다. 분산되어 있는 루팅 제어기능이 총괄명번역 서비스를 수행하기 위하여 사용하는 루팅 제어 데이터의 일치성을 유지하기 위하여, 관리 기능에 루팅 제어 데이터를 총괄적으로 관리하는 루팅 제어 데이터 관리 기능(RCDMFB : Routing Control Data Management Function Block)과 운용 관리 기능 (OMS : Operation and Management Subsystem)의 제원관리 지원기능을 구현하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.415-419
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• 2002

The mutual interchange and cooperation giving first consideration to the communication technology and industry makes it possible to advance the day of unification of North and South Korea. For the sake of this, it is necessary to build communication network connecting all parts of Korea synthetically. This paper presents the plan to build the realizable communication system in North Korea. It bases on an objective view and prospect of domestic and foreign conditions and will help to construct the communication inflation. Therefore, consideration of pluralistic, economic and relay aspects must be proceeded and also the least expense of unification must be deliberated.

• Journal of the Korean Society for information Management
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• v.19 no.1
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• pp.23-46
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• 2002

With explosively increasing digital contents, library and Information center should have a new role between knowledge providers and knowledge users as information brokering organization. Electronic transaction system should be required for performing this brokering service since economic value is added to information and knowledge in information society. The developments and changes around library are keeping up with increasing building digital library and digitalizing printed sources. With the rapidly changing circumstances, the Internet is currently witnessing an explosive growth. By serving as a virtual information resource. the Internet can dramatically change the way business is conducted and Information is provided. However because of features o( the Internet like openness and information sharing, it has fundamental vulnerabilities in security issues. For Instance, disclosure of private information and line eavesdropping such as password, banking account, transaction data on network and so on are primary obstruction factors to activation of digital contents delivery on network. For high network security and authentication, this paper looks at smart card technologies and proposes multi-authentication protocol based on smart card on open network, implements and analyzes it.

• The Journal of the Korea Contents Association
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• v.12 no.8
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• pp.59-68
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• 2012

The existing ship monitoring system currently in use has a limitation, which is that it can only identify a boat's location for finding a safe harbor or give an answer to a rescue signal. In addition to this, it is very difficult to add an expensive, more effective monitoring system to small boats because of their small infrastructure in comparison with large boats. Therefore, this study suggests that a new model could be required to better cater to the needs of small boats. The 'Smart Care System', based on location, is better able to monitor the boat and the crew of small boats in comparison with the existing ship monitoring system. Using biomedical data transmission equipment, it is able to survey and send biomedical data so that it can continuously monitor the crew's health. The boat has an intelligent interface device, which has the functions of GPS and attitude sensors, and a web based management system. We have conducted three experiments for the assessment of this system. The experiment of biological data transmission had a success rate of 98 percent, and the tests conducted for recognizing emergency situations also had a 98 percent success rate. In conclusion we confirmed the efficiency of this system.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.1
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• pp.12-17
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• 2018

This study describes the design and implementation of Antenna for Digital Satellite Communication. The Antenna unit for SHF band consists of Reflector, Septom Polarizer, Feed Horn and Support Frame etc. Thought analysis of space environment before production, the possibility of the malfunction of equipment minimized and we designed a reliable Antenna through simulation for vibration and thermal analysis generated during the launch, and compared pre-simulation of main performance results to test results about main performances of Antenna after production. After fabricating the antenna, the maximum gain of the antenna main beam is 36.5dBi, which satisfies the requirement of 35dBi or more, and it also satisfies the requirement of -20dB for return loss of less than -24dB. Also, the isolation of the transmission and reception of the antenna is -22.6dB or less, which satisfies the requirement of -20dB or less. The antenna for digital satellite communication described in this paper can be used in the satellite field of geostationary earth orbit and low earth orbit requiring high reliability in the future.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.9 s.351
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• pp.60-68
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• 2006

Using the wireless communication among unacquainted vehicles, an intelligent vehicle safety system can be constructed to exchange vehicle safety-related information, such as urgency stop, traffic accident and road obstacles. In the majority of vehicle safety applications, vehicle safety messages are propagated in the form of broadcast. However, this approach causes some effectiveness and performance problems with massive radio collision, multi-hop propagation. This paper presents a priority based relay node selection method for propagating vehicle safety messages of traffic accident protection system. With this method, vehicle safety messages are relayed by a node that locates in proper distance out of the nodes that are included in the radio transmission range. By decreasing the number of duplicated messages, the packet overhead is lessened while the communication performance is raised. The proposed method was proven to be better than other schemes through network simulations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.341-350
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• 2007

In this paper, the derivation of protection ratio is newly proposed for the detailed planning of frequency coordination in microwave relay networks, and computed results for protection ratio of co-channel and adjacent channel are illustrated over the actual system and its frequency. It is shown that the suggested method based upon availability prediction can be expressed in terms of composite fade margin, interference-to-noise ratio(I/N), net filter discrimination, and system parameters. According to results, for 6.7 GHz, 60 km, 64-QAM, and I/N= -6 dB at BER $10^{-6}$, composite fade margin and co-channel protection ratio provide 25.5 and 50.7 dB, respectively. Also, net filter discrimination and adjacent channel protection ratio are obtained as 26.3 and 24.4 dB, respectively, at the first adjacent channel of 40 MHz. The proposed method provides some merits in computing protection ratio for microwave relay networks in view of an easy extension and practical applications considering more detailed and various system parameters.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.571-573
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• 2018

Wireless sensor networks have unbalanced energy consumption due to the convergence structure in which data is concentrated to sink nodes. To solve this problem, in the previous research, the relay node was placed between the source node and the sink node to merge the data before being concentrated to the sink node. However, selecting a relay node that does not consider the link quality causes packet loss according to the link quality of the reconfigured routing path. Therefore, in this paper, we propose a link cost calculation method for data reliability in routing path reconfiguration for relay node selection. We propose a link cost estimation formula considering the number of hops and RSSI as the routing metric value and select the RSSI threshold value through the packet transmission experiment between the sensor modules.