• Journal of information and communication convergence engineering
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• v.7 no.3
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• pp.309-313
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• 2009

In this paper, end-to-end VoIP(Voice over Internet Protocol) performance is evaluated by simulation with NS-2 simulation tool. There are many results studied and published for VoIP performance over TCP/IP networks. But, almost all of them were focused on wired or wireless Internet environments. About MANET (Mobile Ad Hoc Network), VoIP is currently studying several points of research. In this paper, analysis of VoIP performance is done with focusing on the mobility of MANETs. MOS(Mean Opinion Score), network delay, packet loss rates are considered as end-to-end QoS performance parameters.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.361-364
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• 2008

최근 언제 어디서나 컴퓨팅이 가능한 Ubiquitous Computing System 을 구현하기 위한 연구가 활발히 진행되고 있다. 또한, 이를 구현하기 위해 사용자의 상황에 따라 최적의 서비스를 제공하기 위한 상황인식 (Context-awareness) 컴퓨팅 기술 또한 많은 연구가 진행되고 있다. 본 논문에서는 Ubiquitous Computing System 을 구현하기 위해 복합 센서로부터 입력되는 다양한 상황 정보에 대해 CRS(Context Recognition Switch) 개념을 포함하여 보다 정확하고 빠르게 사용자의 상황 정보를 추출하게 된다. 또한 제안된 DOS(Dynamic and Optimal Standard) 개념으로부터 노드의 고유 속성을 분석하여 특화된 시스템 서비스가 가능한는 IEEE 802.15.4 WPAN Standard 기반의 UoC(Ubiquitous system on Chip) Architecture 를 제안하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.958-961
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• 2007

Recently, research and deployment have been very active on wireless mesh technologies. Wireless mesh networks extends the coverage of the WLAN easily and economically. Although existing protocols developed for MANET and WSN can be used for wireless mesh WLANs, considerable amount of research are still required, because they exhibit poor performance, when applied as they are, due to a few critically different requirements This paper examine research issues on physical and link layers of WLANs considering those requirements.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.1347-1350
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• 2005

거의 모든 종류의 이동기기에서 에너지를 절감하는 것은 중요한 연구주제들중의 하나이다. 본 논문에서는 낮은 전원을 소모하는 슬립 모드로의 전환이 가능한 노드들로 구성된 MANET(mobile ad hoc networks)에서 에너지를 절감하는 새로운 프로토콜을 설계한다. 본 논문에서 고려하고 있는 MANET는 예측할 수 없는 호스트의 이동성, 멀티홉에서의 호스트들 간의 통신 그리고 비동기적인 메커니즘을 사용하는 특징을 가지고 있다. 특히 우리는 노드의 동기화가 에너지 절감 프로토콜의 복잡성에 어떤 영향을 미치는지에 대하여 연구한다. 또한 IEEE 802.11기반 multi-hop ad hoc network에 적용할 수 있고 동기적으로 전원을 관리하는 SPFAI(Synchoronous PFAI), ESPFAI(Efficient SPFAI), NSPFAI(Non-MTIM SPFAI)의 세가지 에너지 절감 프로토콜을 제안한다.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.4
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• pp.143-149
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• 2012

MANET is a network that is a very useful application to build network environment in difficult situation to build network infrastructure. But, nodes that configures MANET have difficulties in data retrieval owing to resources which aren't enough and mobility. Therefore, caching scheme is required to improve accessibility and availability for frequently accessed data. In this paper, we proposed a technique that utilize mobility prediction of nodes to retrieve quickly desired information and improve data availability. Mobility prediction of modes is performed through distance calculation using location information. We used technique which global cluster table and local member table is managed by cluster head to reduce data consistency and query latency time. We compared COCA and CacheData and experimented to confirm performance of proposed scheme in this paper and efficiency of the proposed technique through experience was confirmed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.5
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• pp.2218-2244
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• 2016

In this paper, we propose a hybrid routing scheme that utilizes location information to support reliable data transmission in mobile ad hoc networks. The proposed scheme determines and maintains routing path by considering the directionality and connectivity of nodes using grid zones and information on neighbor nodes. In addition, it generates alternative paths with consideration for node distance and reliability. To show the superiority of the proposed routing scheme, a performance evaluation was conducted using simulations. The performance evaluation results show that the proposed scheme offers faster and more reliable data transmission than the existing routing schemes, and the number of messages decreases by approximately 31% compared to the existing schemes on average.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.214-216
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• 2003

Mobile Ad Hoc Network(MANET)에서는, 각 모바일 노드들이 하나의 연결을 유지하는 단말 호스트로 동작함과 동시에 라우터로서도 동작한다. 따라서 유선 네트워크와는 달리 라우터 뿐만 아니라 단말 호스트에서의 네트워크 혼잡이 고려의 대상이 되어야 한다. 네트워크 계층 간에 동작하는 플로우 컨트롤 알고리즘을 사용한다면, 단말 호스트(플로우의 소스 혹은 목적 노드)에서의 패킷 드롭을 줄임으로써 TCP throughput율 증가시킬 수 있다. 일반적으로 MANET의 링크 레이어 프로토콜로는 IEEE 802.11 MAC 프로토콜이 많이 사용되지만, 이 프로토콜은 링크 레이어에서의 플로우 컨트롤을 제공하지는 않는다. 링크 레이어 플로우 컨트롤은 패킷이 전송된 직후에 버퍼 오버플로우로 인해 드롭되는 것을 방지할 수 있으며, 이는 결과적으로 대역폭의 낭비와 전력사용을 줄일 수 있다. 이 논문에서 2개의 플로우 컨트롤 알고리즘, 즉 수직 플로우 컨트롤과 수명 플로우 컨트롤을 제안한다.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.137-138
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• 2006

NEMO(Network MObility) is a complex model of mobile network which refers to a forming of Nested Mobile Network by a moving transportation like vessel, bus, or a train which then moves a Mobile Node, or by a movement of a PAN(Personal Area Network). In a Nested NEMO, pinball routing is the primary obstacle as exemplified by the IPv6 environment. This paper will focus on improving such models as RRH, RBU+ and MANET Approach, that attempted to solve pinball routing by route optimization.

• Journal of IKEEE
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• v.7 no.2 s.13
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• pp.127-134
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• 2003

Ad Hoc Networks, autonomous distributed network using routing scheme, does not operate properly owing to multi flow service when network load increases at specific network node. In this paper, we suggest traffic management routing protocol in Ad Hoc Network to reduce network traffic congestion and distribute network load in data transmission. Through test results of proposed algorithm under NS(Network Simulator)simulator environments . we acquired reduced network load and increased data transmission rate.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04b
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• pp.1539-1542
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• 2002

Many routing protocols have been proposed for mobile ad-hoc networks, but most protocols do not consider the physical location of the communicating nodes. In this paper we propose adaptive zoning approach with multiple hosts for reducing the number of route request messages. The proposed approach makes the sub-request zone has shorter interval than the existing schemes between the source and destination. This results in significantly lower routing overhead than the existing schemes as verified by computer simulation.