• Journal of KIISE:Information Networking
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• v.31 no.6
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• pp.643-658
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• 2004

Mobile ad hoc networks(MANET) have recently attrarted a lot of attention in the research community as well as in industry. Although the previous research mainly focused on the various problems of MANET in data link and network layers, we consider, in this paper, how to efficiently support applications such as service discovery on top of MANET. Peer-to-Peer(P2P) overlay network can be adopted to service discovery mechanism because P2P and MANET share certain similarities, primarily the fact that both arc instances of self-organizing decentralized systems. Especially, distributed hash table(DHT) systems used for r2r overlay network can be effective in reducing the communication overhead in service discovery. However, since overlay network is independent of physical network topology and existing topology-aware mechanisms are based on the wired network, they are inefficient in MANET. We propose a proximity-based overlay network routing to overcome the inefficiency of routing in overlay network. In the proximity-based overlay network routing, each node collects information of physically close nodes by using one hop broadcast and routes messages to the logically closest node to destination. In a detailed ns-2 simulation study, we show that the proximity-based overlay network routing reduces the number of physical hops comparable to the flooding-based mechanism with low communication overhead. We also find that the proposed scheme works well in the mobile environment.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.547-549
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• 2004

모바일 애드혹 네트워크(mobile ad hoc network)는 기간망(infrastructure network)에 대한 의존 없이 무선을 통해 이동 노드들(mobile nodes)간의 통신만으로 동작하는 네트워크이다. 모바일 애드혹 네트워크에 참여하는 모든 노드는 다른 노드들과 통신을 하기 위해 IP주소를 동적으로 할당받아야만 한다. 본 논문에서는 모바일 애드혹 네트워크에 참여하는 각각의 모든 노드들에게 서로 구별되는 유일한 주소를 동적으로 할당할 수 있는 토큰-기반 동적 주소 할당 프로토콜을 제안하고, 시뮬레이션을 통하여 성능 평가를 함으로써 기존의 프로토콜들에 비해 더 효율적으로 노드들에게 주소를 할당함을 보이고 있다.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.1425-1428
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• 2004

모바일 애드 혹 네트워크의 제한된 자원과 다양한 토폴로지 변화 때문에 모바일 애드 혹 네트워크를 관리하고 QoS를 보장하기란 매우 어려운 일이다. 또한 현재까지 모바일 애드 혹 네트워크에서 QoS 보장에 대한 관심은 많지만, 그에 대한 연구는 아직까지 미비한 실정이며 주로 MAC 프로토콜과 라우팅 프로토콜에 집중되어 있다. 따라서 본 논문에서는 차등화 서비스(DiffServ) QoS 모델을 기반으로 하는 정책기반 망 관리 기술과 동적으로 네트워크의 기능을 확장할 수 있는 액티브 네트워크 기술을 이용하여 모바일 애드 혹 네트워크를 효율적으로 관리하고 QoS를 제공할 수 있는 프레임워크를 제안한다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.2
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• pp.29-36
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• 2007

Ad hoc network does not need any preexisting network infrastructure, and it has been developed as temporal networks in the various fields. Infostation is an efficient system to transfer information which does not have delay sensitive characteristics. In this paper, we propose a disaster emergency management system using sensor attached animals' mobility combined with infostation system. We also analyze the performance of the proposed system by simulation. From the performance analysis results, we expect that the proposed system will be very useful to early detect big forest fires which occurs frequently in Korea mountain areas.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.112-114
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• 2006

3세대 이동통신 망에서는 릴레이 노드를 이용한 셀룰러 망과 애드혹 망의 통합을 통해 셀의 용량 및 셀 커버리지의 증가와 인접 셀 간의 부하 밸런싱 효과를 제공할 수 있다. 이러한 이종 무선 통합 망 환경에서 QoS를 제공하기 위해서는 이종 망 간에 데이터 전송 시 서로 다른 망 간의 네트워크 용량을 고려하여 데이터 릴레이 및 QoS 레벨을 일치시켜 줄 수 있는 릴레이 노드의 중계 역할이 필요하다. 본 논문에서는 과금 서비스에 기반한 보상금과 수익금 제도를 통하여 애드혹 노드와 셀 기지국 간의 데이터 릴레이 기능 및 QoS를 제공하는 협상 에이전트 기법을 제안하며 ns-2 기반 UMTS/WLAN 시뮬레이터를 이용하여 성능을 분석한다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.487-489
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• 2003

애드 혹 망은 유선 기반망 없이 무선 노드만으로 구성된 망을 말한다. 이러한 특징으로 인하여 빠른 망 구축을 가능하게 하지만, 망의 동적인 구조와 노드들의 이동성을 고려할 때 효율적인 데이터 전송을 위한 경로 유지는 중요한 문제로 대두된다. 본 논문에서는 애드 혹 라우팅 프로토콜 중의 하나인 AODV(Ad­hoc On­demand Distance Vector) 라우팅 프로토콜에서의 지역복구 (local repair) 시 경로설정 패킷의 플러딩 범위를 제한하는 범위 제한적(seeped) 플러딩을 이용한 효율적인 지역복구 기법을 제안한다. 이 방법의 경우 기존의 AODV 지역복구에 비해서 경로설정 오버헤드를 줄이고 데이터 전송률을 높일 수 있다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.3
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• pp.165-171
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• 2009

With rapid growth of Mobile Ad-Hoc network(MANET) and P2P service technologies, many attempts for integration of MANET and P2P service and development of such applications are actively introduced recently. The implementation of stable P2P service, however, is very difficult challenge because of the high mobility of mobile users in MANET. In this paper, we propose an efficient mobile P2P service, which shares and manages multimedia data files efficiently in mobile environment, uses distributed caches to store files considering their popularities in order to achieve high performance. The performance of proposed P2P service is evaluated by an analytic model and compared with those of existing DHT based P2P service in peer-to-peer network.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.2
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• pp.9-14
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• 2008

Mobile Ad-Hoc network is the network of mobile nodes which has no fixed infrastructure, and mobile node in MANET can move freely and communicate with each other. The location management is an important issue because location information of a mobile node is frequently changed in MANET. In this paper, we propose new quorum system applying the gravity of locality of mobile nodes adaptively by using the fuzzy-logic for the mobility of mobile nodes in order to manage location information of mobile nodes in MANET efficiently. The performance of the proposed scheme is evaluated by an analytical model and compared with those of existing UQS and DQS schemes.

• Journal of the Korean Data and Information Science Society
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• v.21 no.6
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• pp.1125-1136
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• 2010

Lately there exist increasing demands for online abnormality monitoring over trajectory stream, which are obtained from moving object tracking devices. This problem is challenging due to the requirement of high speed data processing within limited space cost. In this paper, we present a FADA (Fuzzy Anomaly Detection Algorithm) which constructs normal profile by computing mobility feature information from the GPS (Global Positioning System) logs of mobile devices in MANETs (Mobile Ad-hoc Networks), computes a fuzzy dissimilarity between the current mobility feature information of the mobile device and the mobility feature information in the normal profile, and detects effectively the anomaly behaviors of mobile devices on the basis of the computed fuzzy dissimilarity. The performance of proposed FADA is evaluated through simulation.

• Journal of KIISE:Information Networking
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• v.31 no.3
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• pp.327-334
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• 2004

In this paper, we make MAC protocol improvements for performance enhancement of multi-hop ad-hoc wireless networks. A node in ad-hoc wireless networks can transmit a packet only when the medium is available, and while a packet is being transmitted, no other nodes are allowed to transmit a packet if they are in carrier sensing range. Carrier sensing range can be divided into two disjoint areas of transmission range and carrier sensing zone(9), and we address the importance of the protocol behavior when a node is in carrier sensing zone. The characteristic of the carrier sensing zone is that a node can not know when the remaining time of the on-going transmission session expires or exactly when the media becomes available. Current MAC protocol does not behave in much different way between when a node is in transmission range and in carrier sensing zone. We have conducted a comprehensive simulation to study the performance improvements. The simulation results indicate that the performance is increased and the number of dropped packets due to collision is significantly reduced as much as a half.