• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.7
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• pp.1306-1312
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• 2017

The route request (RREQ) packet is selectively re-broadcasted in the routing protocols that improve the broadcast storm problem of the ad-hoc on-demand routing protocol (AODV). However, in a low node density scenario, the connectivity of these selective rebroadcast schemes becomes less than that of the AODV. In order to clarify the requirements of these selective re-broadcast routing protocols, it is necessary to investigate the relationship between the node density and the connectivity. In this paper, we drive a probability to preserve the connectivity of the GAODV at an intermediate rebroadcast node. In addition, we present an intuitive method to approximate the end-to-end connectivity of the GAODV. We draw the required node density to guarantee the connectivity of 0.9 and 0.99 through computer simulations, and verify the validity of the derived theoritical connectivity by comparing with the simulation results.

• Journal of Digital Convergence
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• v.11 no.5
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• pp.279-284
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• 2013

This paper proposes a new cluster-based routing protocol for assuring the service lifetime of wireless multimedia sensor networks. The proposed protocol performs the intra-cluster routing and inter-cluster routing to reduce the energy consumption and service lifetime in the wireless sensor multimedia computing environment, and the proposed mechanism enhances the routing reliability, and it minimizes the packet loss, overhead, and energy consumption. The simulation results show that the proposed mechanism outperforms DSR and AODV.

• Journal of the Korea Safety Management & Science
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• v.12 no.3
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• pp.315-320
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• 2010

Recently, there are environmental issues for sustainable transportation system to pursue the energy-efficient and environment-friendly public urban transit. These transportation system needs to offer demand-oriented high-quality service being on the same level with cab service for urban space. PRT(Personal Rapid Transit), small track-guided vehicle, is repeatedly mentioned as a possible alternative for the new urban public transportion system, but but there are not many researches on the operational optimal routing for PRT network. In this paper, the concept of PRT and general optimal routing methods are reviewed. And we suggest the optimal routing method for city-wide PRT network with multi-vehicles and stations, junctions and directional arcs. Futher research directions for PRT routing are presented.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11A
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• pp.1059-1067
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• 2006

AODV(Ad-hoc On-demand Distance Vector) routing protocol was devised for use of mobile nodes in Ad-hoc network. When we use the AODV routing protocol in Ad-hoc networks with high mobility, disturbance of optimized route path and link break occur. In order to solve the shortcomings, this paper proposes a new routing protocol in which new routing control messages are added to the existing AODV. The proposed protocol minimizes link break and transmission delay while is able to secure the optimized route path constantly in changes of network topology The performance of the proposed routing protocol was evaluated by using us2 network simulator. The actual Ad-hoc network test bed provides us the most reliable experimental data for Ad-hoc networks. In order to support this experimental environment, the dissertation also developed an efficient embedded system on which AODV routing protocol, NAT, Netfilter can run and other event message can be verified without declining efficiency. The correct operation of AODV routing protocol has been verified in both the Ad-hoc network test bed in which the embedded system was used, and Ad-hoc networks linked with Ethernet backbone network.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.919-921
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• 2002

본 논문에서는 기존의 Table-driven 방식과 On-demand 라우팅 의 장점을 접목시킨 2-tier 계층구조를 사용한 dynamic한 routing기법을 제안하며 , 구조적으로 취약한 보안 위협 요소들에 대한 안정성을 제공하는 인증 알고리즘을 제안하고 네트워크와 클러스터 헤드의 관리를 위한 신뢰할 수 있는 키 분배 메커니즘을 고찰한다. 또한 기존의 3GPP서비스와의 상호 연동 가능성을 고려하여 클러스터 헤더의 재생성과 강력한 신뢰성을 제공할 수 있는 알고리즘을 제안한다.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.6
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• pp.131-138
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• 2008

Mobile Ad hoc NETworks (MANETs) refer to autonomous networks in which wireless data communications are established between multiple nodes in a given coverage area without a base station or centralized administration. Because of node mobility and limited battery life, the network topology may changes frequently. Selecting the most reliable path during route discovery process is important to improve performance in ad hoc networks. In this paper, an enhanced routing protocol based on AODV(Ad hoc On-demand Distance Vector routing) by monitoring variation of receiving signal strength is proposed. New metric function that consists of node mobility and hops of path is used for routing decision. For preventing route failure by node movement during data transmission, a new route maintenance named as LRC (Local Route Change) is presented. If the node movement is detected, the routing agent switches path to its neighbor node in LRC. Simulation results show that the performance of the proposed routing scheme is superior to previous AODY protocol.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.127-128
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• 2009

위치기반 라우팅 프로토콜에서의 기본 가정인 이웃 노드들과의 주기적인 위치정보 교환은 노드의 이동성이 있는 경우, 그 성공률을 보장하기가 어렵다. GPSR[1]에서 제안하고 있는 1-홉 거리에 있는 노드들의 정보를 테이블로 관리하는 방식은 데이터 전달이 없는 지역에서도 주기적인 비콘의 교환으로 불필요한 에너지 소모가 있으며, 노드들의 위치가 변경되었을 때, 비콘 (beacon)을 수신한 시점의 위치정보와 데이터 전달시점의 위치정보의 불일치 가능성을 배제할 수 없다. 따라서, 본 논문에서는 노드의 이동성이 빈번한 환경의 위치기반 라우팅 프로토콜에서 데이터전달시점에 이웃 노드들의 정보를 바탕으로 다음 전송노드를 선택하는 방법을 제안한다.

• The Journal of Engineering Research
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• v.7 no.1
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• pp.37-51
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• 2005

An and hoc network is a collection of wireless mobile nodes forming a temporary network without the centralized administration. Due to the limited transmission range of wireless work interface, multiple networks "hops" maybe needed for one node to exchange data with adjacent node. In recent years, a variety of new routing protocol about ad hoc network was developed. This paper presents a new routing protocol based on the Dynamic Source Routing which is not suitable for the high mobility ad hoc network. The Enhanced DR adapts quickly to routing changes when node movement is frequent. When a trunk route is broken, this protocol will utilize the alternative route saved in the route to discovery quickly the new route. It improves the performance of the existing DSR algorithm, so that the negative impacts from weakness of DSR are reduced.

• Journal of Information Processing Systems
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• v.8 no.4
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• pp.589-602
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• 2012

With the increasing demand for real time applications in the Wireless Senor Network (WSN), real time critical events anticipate an efficient quality-of-service (QoS) based routing for data delivery from the network infrastructure. Designing such QoS based routing protocol to meet the reliability and delay guarantee of critical events while preserving the energy efficiency is a challenging task. Considerable research has been focused on developing robust energy efficient QoS based routing protocols. In this paper, we present the state of the research by summarizing the work on QoS based routing protocols that has already been published and by highlighting the QoS issues that are being addressed. The performance comparison of QoS based routing protocols such as SAR, MMSPEED, MCMP, MCBR, and EQSR has also been analyzed using ns-2 for various parameters.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.5
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• pp.82-96
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• 2020

The Demand Responsive Transit (DRT) system is the flexible public transport service that determines the route and schedule of the service vehicles according to users' requests. With increasing importance of public transport systems in urban areas, the development of stable and fast routing algorithms for DRT has become the goal of many researches over the past decades. In this study, a new heuristic method is proposed to generate fast and efficient routes for multiple vehicles using demand clustering and destination demand priority searching method considering the imbalance of users' origin and destination demands. The proposed algorithm is tested in various demand distribution scenarios including random, concentration and directed cases. The result shows that the proposed method reduce the drop of service ratio due to an increase in demand density and save computation time compared to other algorithms. In addition, compared to other clustering-based algorithms, the walking cost of the passengers is significantly reduced, but the detour time and in-vehicle travel time of the passenger is increased due to the detour burden.