• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12A
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• pp.1015-1023
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• 2011

In maritime communication, QoS problem caused by routing is very important. In this paper, we propose a method based on AOMDV protocol providing a route recovery mechanism when a link breaks in an active route to reduce lost packets. The results show that the proposed method can reduce packet loss ratio and delay time compared with the AOMDV.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.2
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• pp.271-287
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• 2013

We propose a new multipath-based reliable routing protocol on MANETs, Multipath-based Reliable routing protocol with Fast-Recovery of failures (MRFR). For reliable message transmission, MRFR tries to find the most reliable path between a source and a destination considering the end-to-end packet reception reliability of the routes. The established path consists of a primary path that is used to transmit messages, and the secondary paths that are used to recover the path when detecting failures on the primary path. After establishing the path, the source transmits messages through the primary path. If a node detects a link failure during message transmission, it can recover the path locally by switching from the primary to the secondary path. By allowing the intermediate nodes to locally recover the route failure, the proposed protocol can handle the dynamic topological change of the MANETs efficiently. The simulation result using the QualNet simulator shows that the MRFR protocol performs better than other protocols in terms of the end-to-end message delivery ratio and fault-tolerance capability.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.5
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• pp.197-203
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• 2012

This paper studies network recovery method using logical multiple ring architecture embedded in WDM optical Internet environment. The multiple ring-based recovery method provides fast and simple network restoration operation, and performs local recovery that is detouring the failed link. The multiple ring architecture can provide higher resource efficiency by sharing the backup routes and reducing the number of spare wavelengths. This paper calculates the required spare capacity ratio using Cut-Sets in the given network topology and performs simulation for comparative analysis.

• Annual Conference of KIPS
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• 2016.04a
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• pp.124-126
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• 2016

Successful deployment of the Software Defined Network (SDN) depends on its ability to cope up with network failures. There are various types of failures that may occur in an SDN. The most common are switch and link failures. It is necessary to recover the network from failures for a continuous service availability. But for the real-time services fast recovery from the failure is required to minimize the service disruption time. In the proposed work, we focused on minimizing the recovery time after the failure is detected. Once the failure is detected, the controller involvement is needed to dynamically reroute the failure disrupted flows from the failed component to an alternate path. The aim of the proposed scheme is to provide a traffic management scheme which can react to the dynamic network events by rapidly modifying the forwarding behavior of the switches for faster in-band network adaptability. The proposed scheme (1) Considers the shared data and control path delay (2) Optimally utilize the network resources (3) Eliminates the need of constant monitoring overhead at the controller which results into faster detouring and ultimately rapid recovery.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.12
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• pp.3081-3099
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• 2012

We propose a new multipath-based reliable routing protocol on MANETs, Multipath-based Reliable routing protocol with Fast-Recovery of failures (MRFR). For reliable message transmission, MRFR tries to find the most reliable path between a source and a destination considering the end-to-end packet reception reliability of the routes. The established path consists of a primary path that is used to transmit messages, and the secondary paths that are used to recover the path when detecting failures on the primary path. After establishing the path, the source transmits messages through the primary path. If a node detects a link failure during message transmission, it can recover the path locally by switching from the primary to the secondary path. By allowing the intermediate nodes to locally recover the route failure, the proposed protocol can handle the dynamic topological change of the MANETs efficiently. The simulation result using the QualNet simulator shows that the MRFR protocol performs better than other protocols in terms of the end-to-end message delivery ratio and fault-tolerance capability.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.2
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• pp.103-111
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• 2019

The combined cycle plant is an integration of gas turbine and steam turbine, combining the advantages of both cycles. It recovers the heat energy from gas turbine exhaust to use it to generate steam. The heat recovery steam generator plays a crucial role in combined cycle plants, providing the link between the gas turbine and the steam turbine. Simulation of the performance of the HRSG is required to study its effect on the entire cycle and system. Computational fluid dynamics has potential to become a useful to validate the performance of the HRSG. In this study a solver has been implemented in the open source code, OpenFOAM, for combustion simulation in the heat recovery steam generator. The solver is based on the steady laminar flamelet model to simulate detailed chemical reaction mechanism. Thereafter, the solver is used for simulation of HRSG system. Three cases with varying fuel injections and gas turbine exhaust gas flow rates were simulated and the results were compared with measurements at the system outlet. Predicted temperature and emissions and those from measurements showed the same trend and in quantitative agreement.

• Journal of Power Electronics
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• v.9 no.6
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• pp.892-902
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• 2009

This paper deals with the dynamic voltage control problem at the inverter end of a HVDC link when connected to a weak AC system which has the potential for harmonic instability and commutation failures. The dynamic voltage control problem is tackled with a STATCOM (Static Compensator), which not only provides a rapid recovery from harmonic instability and commutation failures but also offers a lower cost filter design for HVDC systems. PSCAD/EMTDC simulations are presented to validate the proposed topology and to demonstrate its robust performance.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.247-250
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• 2002

It is predicted that the existing backbone network has encountered its limit due to massive growth in data traffic. Perhaps new WDM methods utilizing optical fibers are desirable. Also to assure reliance of the network detour routes fur collision recovery must be considered. But due to the redundancy occurred by allocating bandwidths to the detour route, the efficiency of the link my decline. In this paper, we designed a detour route to minimize the redundancy.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.340-342
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• 2004

악의 있는 해커들은 악성 프로그램을 이용하여 시스템에 침입하고 파일을 변경(추가, 수정, 삭제)함으로써 일반 사용자로 하여금 올바른 정보를 받아 보지 못하게 한다. 그라나 침입이 있더라도 사용자에게 신뢰성 있는 정보를 제공하기 위하여 로그기반 침입복구모듈을 제안하고 구현하였다. 구현된 로그기반 침입복구모듈은 복구를 위해 사용될 로그를 관리하기 위하여 많은 오버헤드가 발생했다. 본 논문에서는 로그기반 침입복구모듈의 성능을 개선하기 위하여 링크 정보를 관리하는 방법을 제안한다. 그리고 개선된 로그기반 침입복구모듈의 성능을 측정하여 변경 전과 비교한다.

• Journal of KIISE:Information Networking
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• v.37 no.1
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• pp.35-41
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• 2010

Since the ad-hoc network allow nodes to communicate each other without infrastructure system and predefined configuration, it comes into the spotlight that is suitable to ubiquitous society. In ad-hoc network, route recovery mechanism is considered important. Normally route recovery is needed to solve the link failure problem because there is no route maintaining system like a router in ad-hoc networks. In this paper we propose BS-AODV(Bidirectional Searching-AODV) route recovery method. The proposed method is a local repair method that can be applied in all of the network area. Unlike a limited local repair method in AODV. the proposed method adopts the bidirectional searching method where the upstream/downstream nodes can send the route maintenance messages. Restricting the flooding of route request messages, the proposed scheme attempts to minimize the costs of local repair, the performance of the proposed scheme is evaluated through the simulations. In two scenarios which variate the node numbers and node speed, the comparison among the proposed scheme, AODV and AOMDV is shown in terms of the control traffic and data delivery ratio.