• Annual Conference of KIPS
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• 2008.05a
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• pp.721-724
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• 2008

무선 센서 네트워크(WSN)를 구성하는 각 센서 노드들의 에너지 관리는 네트워크 전체의 생명주기에 영향을 미치는 요소 중 가장 중요한 요소이다. 센서 노드들은 한번 설치된 이후 짧게는 수개월에서 길게는 몇 년에 걸쳐 동작해야 하기 때문에 배터리에 의존하고 있는 센서 노드들의 에너지를 효율적으로 관리할 수 있는 기술들이 필요하다. Directed Diffusion은 센서 노드에서 수집한 데이터를 네트워크 전체에 브로드캐스팅 하지 않고, 소스(Source)노드로부터 싱크(Sink)노드까지 강화(Reinforce)된 경로를 통해서만 데이터를 전송하여 경로 이외의 노드들의 불필요한 에너지 소모를 줄일 수 있는 라우팅 프로토콜이다. 그러나 기존의 Directed Diffusion에서는 전송 경로 상에 장애가 발생했을 경우 싱크에서 전송한 익스플로러터리 패킷을 기다려야 하며, 장애가 발견되고 재전송되기 전까지 전송된 데이터는 무의미한 데이터가 된다. 본 논문에서는 앞서 언급된 Directed Diffusion의 장애 경로 복구의 문제점을 보완하기 위해 Fast Repair(FR)를 제안한다. FR은 데이터 전송 경로 상에 장애 발생 시 데이터를 재전송 하고 경로를 재설정하는데 효율적이며, 성능평가 결과에서도 기존의 Directed Diffusion에 비하여 향상된 성능을 나타내고 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.8
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• pp.1567-1576
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• 2015

This paper proposes a reliable real-time data dissemination protocol for mitigating transmission failure of real-time data in WSNs. The re-transmission is well-known for recovery of transmission failure, but this may violate the real-time requirement by transmission delay. To solve this problem, the proposed protocol exploits broadcasting nature and temporal opportunity allocation. In a radio-range of sending node, there may be neighbors satisfying the real-time requirement. The neighbors of specific node could receive data simultaneously by broadcasting, and decide their priority using temporal opportunity allocation method. The method uses time slot and tolerable time. The time slot specifies the priority and transmission deadline for each neighbors, and the tolerable time is the real-time requirement at the sending node. By giving the priority to the node with shorter tolerable time in each slot, we may get more opportunities to forward toward the destination. In other words, even if a node have the longer tolerable time, it still has a chance to forward with the real-time requirement. Simulation results show that the proposed protocol is superior to the existing protocols.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5B
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• pp.274-286
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• 2005

In this paper, we propose a new power-efficient and reliable connected dominating set based routing protocol in the mobile ad hoc networks. Gateway nodes must be elected in consideration of residual energy and mobility because frequent reconstruction of connected dominating set result in transmission error for route losses. If node density is high, it results in a lot of contentions and more delays for network congestion. Therefore, in this paper, we propose a new construction method of connected dominating set that supports reliable and efficient data transmission through minimizing reconstruction of connected dominating set by delaying neighbor set advertisement message broadcast in proportion to weighted sum of residual energy, mobility, and the number of neighbor nodes. The performance of the proposed protocol is proved by simulation of various conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.108-120
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• 2017

To this end, the ROK military is developing a Korean Tactical Data Link (Link-K) in two stages: Basic and Completion types. Currently, the basic type of the Link-K has a limitations for supporting Mission Group(MG)s, such as to share unnecessary information and inefficient routing, because all RICCs simply broadcasts the same information in the basic type of the Link-K. In this paper, we propose a Zone-based Wireless Link-K network structure and a routing algorithm. To improve the effectiveness of the proposed routing algorithm, we have studied a filtering method that adjusts the message data according to the priority of the message and a method of controlling the load of the network. In order to evaluate the performance of the proposed scheme, it is proved that it is effective to support the mission task group compared with the existing wireless Link-K routing algorithm according to the operational scenario situation.

• Journal of IKEEE
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• v.11 no.4
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• pp.165-170
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• 2007

The main goal of research concerning clustering protocols is to minimize the energy consumption of each node and maximize the network lifetime of wireless sensor networks. However, most existing clustering protocols mainly focused on the design and formation of clusters, leaving the consideration of communication between the cluster head and the sink behind. In this paper, we propose efficient multi path routing algorithm by using MAC-NET Cross-layering. multi path needed only one tiny packet from sink to setup. In addition proposed algorithm can be used for any cluster-based hierarchical inter-clustering routing algorithm. The simulation results demonstrate that proposed algorithm extended the overall survival time of the network by reducing the load of cluster heads. The performance of proposed algorithm is less affected by the extension of sensing field than other inter-clustering operation.

• Convergence Security Journal
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• v.3 no.1
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• pp.31-37
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• 2003

This paper proposed a model supporting secure mechanism both group communication service and subgroup communication service of TETRA system that the standard developed by the technical committee Radio Equipment and Systems(RES) of the European Telecommunications Standards Institute(ETSI) provides a pure digital information technology for the transmission of speech and data. In each scheme, members in a subgroup maintains its subgroup key, which is not distributed, but computed by each member in the subgroup only with his own secret information and public values and secure subgroup members in a same subgroup can communication securely each other by using their subgroup key. Also, all members in group can share securely a group key. In communication services of TETRA system, this model supports mechanism for both group and subgroup communication are simultaneously needed.

• Journal of the Korea Society of Computer and Information
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• v.13 no.4
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• pp.141-150
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• 2008

In this mobile computing environment, data broadcasting is widely used to resolve the problem of limited power and bandwidth of mobile equipments. Most previous broadcast indexing methods concentrate on flat data. However. with the growing popularity of XML, an increasing amount of information is being stored and exchanged in the XML format. We propose a novel indexing method. called TOP tree(Tree Ordering based Path summary tree), for indexing XML document on mobile broadcast environments. TOP tree is a path summary tree which provides a concise structure summary at group level using global IDs and element information at local level using local IDs. Based on the TOP tree representation, we suggest a broadcast stream generation and query Processing method that efficiently handles not only simple Path queries but also multiple path queries. We have compared our indexing method with other indexing methods. Evaluation results show that our approaches can effectively improve the access time and tune-in time in a wireless broadcasting environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1B
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• pp.144-153
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• 2010

Flooding based routing protocols are usually used to disseminate information in wireless sensor networks. Those approaches, however, require message retransmissions to all nodes and induce huge collision rate and high energy consumption. In this paper, HoGoP (Hop based Gossiping Protocol) in which all nodes consider the number of hops from sink node to them, and decide own gossiping probabilities, is introduced. A node can decide its gossiping probability according to the required average reception percentage and the number of parent nodes which is counted with the difference between its hop and neighbors' ones. Therefore the decision of gossiping probability for network topology is adaptive and this approach achieves higher message reception percentage with low message retransmission than the flooding scheme. Through simulation, we compare the proposed protocol with some previous ones and evaluate its performance in terms of average reception percentage, average forwarding percentage, and forwarding efficiency. In addition, average reception percentage is analyzed according to the application requirement.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.5
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• pp.556-560
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• 2010

In the wireless sensor networks using a multi-hop, quality variation of links occurs irregularly due to the hardware restriction and environmental factor. If an appropriate route, which is affected by the quality variation, is not selected. Traditionally, a beacon is periodically broadcasted and the link quality is estimated. However, the periodically beacon based scheme cannot efficiently estimate the quality of the link changing irregularly. In this paper, a scheme to estimate the link quality adaptively according to network state is proposed. When the link quality changes, the scheme adapts to a change agilely and packet losses are reduced. When there is no change of the link quality, the link quality is estimated in the long period and the energy consumption is reduced. Through performance evaluations, we prove that our adaptive link estimation scheme improves the energy efficiency and packet reception ratio than the periodic estimation scheme.

• Journal of Internet Computing and Services
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• v.8 no.5
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• pp.133-140
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• 2007

Currently, as the requirement for high quality Internet access from anywhere at anytime is consistently increasing, the interconnection of pure ad hoc networks to fixed IP networks becomes increasingly important. Such integrated network, referred to as hybrid ad hoc networks, can be extended to many applications, including Sensor Networks, Home Networks, Telematics, and so on. We focus on some data communication problems of hybrid ad hoc networks, such as broadcasting and routing. In particular. power failure of mobile terminals is the most important factor since it affects the overall network lifetime. We propose an energy-efficient routing protocol based on clustering for hybrid ad hoc networks. By applying the index-based data broadcasting and selective tuning methods, the infra system performs the major operations related to clustering and routing on behalf of ad hoc nodes. The proposed scheme reduces power consumption as well as the cost of path discovery and maintenance, and the delay required to configure the route.