• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.7
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• pp.566-572
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• 2014

We propose a two-way multi-hop relaying scheme improving the throughput as well as enlarging the coverage for ship-to-ship communications in multi-ship marine networks. The proposed scheme reduces the time slots required for the data exchange by designing data transmission and network coding procedures in a sophisticated way based on two-phase digital network coding. Simulation results show that the proposed two-way multi-hop relaying scheme improves the throughput of the conventional one about 5/3 times.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.8
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• pp.688-695
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• 2014

In a small wireless environment, such as your home or office, a various network using WiMedia PHY can be mixed. Because these networks operate independently for each application, data conflict can occur between adjacent networks. To avoid data conflict, the resource in a different time zone can be utilized. However, if devices in a network increase, available resources in the network decrease, and then the lack of resources necessary to provide service can occur. To solve this problem, we propose collision avoidacne scheme for coexistence of various UWB systems. In this paper, we evaluate the performance of the proposed scheme through simulation.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.6
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• pp.1097-1106
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• 2011

Tactical Information Communication Network(TICN), a concept-type integrated Military Communication system that enables precise command control and decision making, is designed to advance into high speed, large capacity, long distance wireless relay transmission. To support mobility in battlefield environments, the application of Ad-hoc networking technology to its wireless communication has been examined. Ad-hoc network works properly only if the participating nodes cooperate in routing and packet forwarding. However, if selfish nodes not forwarding packets of other nodes and malicious nodes making the false accusation are in the network, it is faced to many threats. Therefore, detection and management of these misbehaving nodes is necessary to make confident in Ad-hoc networks. To solve this problem, we propose an efficient intrusion detection technique to detect and manage those two types of attacks. The simulation-based performance analysis shows that our approach is highly effective and can reliably detect a multitude of misbehaving node.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1793-1795
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• 2004

지금까지 변전소나 개폐소에서 전류, 전압을 계측하는 수단으로서 주로 철심과 권선으로 구성되어진 변류기(CT), 계기용 변압기(PT, PD)가 사용되어 왔다 최근, 2차측의 계측기나 보호 Relay의 Digital화가 진전되어, 또한 이것을 Digital Network으로 종합한 Intelligent 변전소의 구축이 검토되어짐에 따라 Digital Network에 대응한 신형 CT, VD가 요구되어 지고 있다. 상기와 같은 요구로 인해 당사에서는 CT는 검출부에 Rogowski Coil을 적용하며 그 후단에 적분기를 설치하였으면, VD는 검출부에 중간 전극을 이용해서 분압하는 방식인 Capacitive Voltage Divider를 사용하고 증폭기를 삽입하여, 각각 요구되는 전압 신호를 얻었다. 이러한 신형 CT/VD의 적용으로 종래의 CT/PT가 차지하는 공간이 필요 없게 되어 컴팩트한 GIS의 구조가 능하게 되어 있다.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.43-46
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• 1991

When a fault is occurred in Power System, relay system detect overcurrent or voltage drop and trip the circuit breaker. Then, an operator in the control room diagnoses the fault and start the recovery of the system after analyzing the alarm information of relays or circuit breakers. The alarm informations have different patterns for each fault of the electric equipments on lines in power systems. In this paper, Back propagation algorithm is applied to train for many kinds of the fault in the power system. The simulation results show the possibility of the neural network application for the fault diagnosis in the case of errorous operation as well as normal operation of relays or circuit breakers.

• Journal of Korea Multimedia Society
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• v.14 no.12
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• pp.1559-1571
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• 2011

In wireless ad hoc networks, nodes communicate with each other using multihop routed transmission in which hop-by-hop cooperative diversity can be effectively employed. This paper proposes (i) two cooperation models for per-link cooperation (PLC) and per-node cooperation (PNC) for exploiting cooperative diversity in wireless ad hoc networks and (ii) a cooperative routing algorithm for the above models in which best relays are selected for cooperative transmission. First, two cooperation models for PLC and PNC are introduced and represented as an edge-weighted graph with effective link quality. Then, the proposed models are transformed into a simplified graph and a cooperative routing algorithm with O(n2) time is developed, where n is the number of nodes in the network. The effectiveness of the algorithm is confirmed for the two cooperation models using simulation.

• KIEE International Transactions on Power Engineering
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• v.4A no.1
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• pp.42-47
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• 2004

This paper presents the various application programs for the Distribution Automation System (DAS) of the Korea Electric Power Corporation (KEPCO)'s distribution system. These programs are developed to allow for optimal operation in the areas of feeder automation, relay coordination, loss minimization and so on. They are single line diagram auto creation programs for the feeder, service restoration program, protection coordination program, data error detection program, and optimal network reconfiguration program. The details of these programs are presented for validity and effectiveness.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.12-14
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• 2006

This paper presents an vulnerability index for hidden failure of protective relays in transmission system. The bad influence can be quantized by an vulnerability index. When there is mis-operation, no-operation or mis-setting, power flow can be quantized by an index. According to the index, relays can be resetting. So the wide area blackout can be prevented.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.337-343
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• 2009

Information theory is one field of the applied mathematics quantitating the data in order to store data as many as in the medium or communicate through channel. it was released on the Shannon's paper, in 1948. With basis on this paper, It has been achieved dramatically development for communication, signal processing, and date procedure and transmission in the network In this paper, the basic concept of information theory is described through dealing with contents about meaning of information, entropy, and channel capacity. It is also handled how information theory is applied to the fields of sensor network, relay channel, MIMO system, and others.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.166-172
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• 1995

It is a general tendency to digitalize the conventional relay based I&C systems in nuclear power plant. But, the digitalization of nuclear safety systems has many a difficulty to surmount. The typical on thing of many difficulties is the data communication problem between local controllers and systems. The network architecture built with LAN(Local Area Network) in digital systems of the other industries are general. But in case of nuclear safety systems many considerations in point of safety and license are required to implement it in the field. In this paper, some considerations for applying LAN in nuclear safety systems were reviewed.