• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.1
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• pp.87-94
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• 2009

The intrusion detection system is one of the active fields of research in wireless networks. Intrusion detection in wireless mobile Ad hoc network is challenging because the network topologies are dynamic, lack centralization and are vulnerable to attacks. Detection of malicious nodes in an open ad-hoc network in which participating nodes do not have previous security association has to face number of challenges which is described in this paper. This paper is about determining the malicious nodes under critical conditions in the mobile ad-hoc network and deals with security and vulnerabilities issues which results in the better performance and detection of the intrusion.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.6
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• pp.1177-1186
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• 2003

The multimedia ad hoc wireless network is quite an attractive issue since it offers a flexible solution to enable delivery of multimedia services to mobile end users without fixed backbone networks. However, with the unique design challenges of ad hoc wireless networks, it is a non-trivial issue to provide bounded delay guarantee, with fair share of resources. In this paper, we implemented the delay guaranteed fair queueing (DGFQ) scheme distributively. Through the results of performance evaluation, we can conclude that DGFQ also performs well to control bounded delay in multimedia ad hoc wireless networks.

• Journal of information and communication convergence engineering
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• v.4 no.2
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• pp.67-70
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• 2006

A distributed healthcare monitoring system prototype for clinical and trauma patients was developed, using wireless sensor network node. The proposed system aimed to measure various vital physiological health parameters like ECG and body temperature of patients and elderly persons, and transfer his/her health status wirelessly in Ad-hoc network to remote base station which was connected to doctor's PDA/PC or to a hospital's main Server using wireless sensor node. The system also aims to save the cost of healthcare facility for patients and the operating power of the system because sensor network is deployed widely and the distance from sensor to base station was shorter than in general centralized system. The wireless data communication will follow IEEE 802.15.4 frequency communication with ad-hoc routing thus enabling every motes attached to patients, to form a wireless data network to send data to base-station, providing mobility and convenience to the users in home environment.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11b
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• pp.1229-1232
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• 2003

Ad Hoc 네트워크에서 on demand 라우팅 프로토콜로 대표적인 AODV(Ad Hoc On Demand Distance Vector Routing)는 table driven 기반의 라우팅 프로토콜과 비교해 active route만을 라우팅 테이블에 저장하기 때문에 오버헤드가 작고 경로단절시 경로복구를 통해 경로 재설정할 수 있는 장점을 가지고 있으나 경로복구시 대역폭 낭비가 심하고 복구시간이 길다는 drawback을 가지고 있다. 이러한 단점은 많은 라우팅 패킷의 발생으로 기인하는 점이 있다. 본 논문에서는 Expanding Ring Search 알고리즘에서 time out은 timestamp를 이용하여 네트워크 상황에 맞게 가변적으로 적용하는 알고리즘을 개선하여 hop 수에 따라 node traversal time을 설정하도록 제안하였다. 제안한 알고리즘은 시뮬레이션을 통하여 검증하였으며 라우팅 패킷의 발생을 줄이고 throughput에서 향상을 보였다.

• Journal of the Korea Society for Simulation
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• v.13 no.2
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• pp.53-63
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• 2004

In ad hoc networks, the link survivability is firstly considered if a routing between two mobile nodes takes place through wireless environments, because all of mobile nodes participating in a connection dynamically move to anywhere. Also, mobile nodes have multi-role to implement a communication without a static system supported by wired networks. Hence, it is difficult that all mobile nodes continuously provide a reliable connection when the nodes operate each role for the connection. Therefore, it is desired to maximize the lifetime of a route as long as possible for the reliable communication. In this paper, we propose a proactive link management scheme that can provide the continuous route supported by the link handover. It consider the wireless link quality and the power lifetime of a node so that the link handover is implemented for the link survivability without disconnecting the route on the communication.

• Journal of Communications and Networks
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• v.14 no.1
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• pp.63-74
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• 2012

Multicast data communication is an efficient communication scheme, especially inmulti-hop ad hoc networks where the media access control (MAC) layer is based on one-hop broadcast from one source to multiple receivers. Compared to unicast, multicast over a wireless channel should be able to deal with varying channel conditions of multiple users and user mobility to provide good quality to all users. IEEE 802.11 does not support reliable multicast owing to its inability to exchange request-to-send/clear-to-send and acknowledgement packets with multiple recipients. Thus, several MAC layer protocols have been proposed to provide reliable multicast. However, additional overhead is introduced, as a result, which degrades the system performance. In this paper, we propose an efficient wireless multicast MAC protocol with small control overhead required for reliable multicast in multi-hop wireless ad hoc networks. We present analytical formulations of the system throughput and delay associated with the overhead.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.829-832
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• 2007

A Mobile Ad Hoc Network is a system of wireless mobiles nodes that dynamically self-organized in arbitrary and temporary network topologies allowing people and devices to inter-network without any preexisting communication infrastructure. Taking into account its nature and challenges and security issues, we present current security solution and analyse the scheme for protecting attacks.

• ETRI Journal
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• v.31 no.1
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• pp.83-85
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• 2009

Compared with unicast, multicast over wireless ad-hoc networks do not support reliability due to their inability to exchange request-to-send/clear-to-send (RTS/CTS) and ACK packets with multiple recipients. Although several media access control (MAC) layer protocols have been proposed to provide reliable multicast, these introduce additional overhead, which degrades system performance. A novel MAC protocol for reliable wireless multicast is proposed in this paper. By adapting orthogonal frequency division multiple access characteristics in CTS and ACK packets, the protocol achieves reliability over wireless multicast with minimized overhead.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.9
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• pp.1654-1662
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• 2006

An ad hoc network is multi-hop network composed of radio links. and the transmission quality of a radio link is more unstable than that of a wired circuit. Packet loss thus occurs frequently in an ad hoc network, and the consequent connection failure results in a severe deterioration of TCP performance. TCP performance also deteriorates because of the collision of data packets and ACK packets in the radio channel. In this paper we study to improve the performance of the Mobile Ad-hoc network by using Delayed ACK algorithm with our proposed ODA(Ordering-Delayed ACK) method. The proposed ODA algorithm increases the number of the data packets orderly at the receiver side which is going to be applied for the Mobile Ad-hoc network. We accomplished a computer simulation using NS-2. From the simulation results, we find the proposed ODA algorithm obviously enlarge the channel capacity and improve the network performance at the situation of multi-hop of ad-hoc network than the existing Delayed ACK algorithm.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.478-481
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• 2003

컴퓨터만을 이용하던 데이터 통신의 개념이 이제는 흠 네트워킹 개념으로 확대되었고 통신 방법도 전력선, 광케이블, 무선 등을 이용하는 방식으로 발전되고 있으며, 핸드폰을 이용한 통신에서 노트북이나 PDA를 이용한 무선 네트워크로 바뀌고 있는 실정이다. 이러한 변화는 일반사회에서는 Ad-hoc 네트워킹에 대한 연구를 발전시키고 있으며, 군사적으로는 C4I, Spider 체계등 군사적 목적의 무선 네트워킹 개념이 연구되고 있다. 본 논문에서는 이런 무선 네트워킹을 AX.25 Protocol을 기반으로 한 TNC와 PDA를 이용 모바일 무전기 데이터 통신 시스템을 구현하고, 이에 대한 성능평가를 통해 Ad-hoc 통신망에서 TNC를 이용한 PDA 무전기를 제안한다.