• Journal of KIISE:Information Networking
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• v.33 no.2
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• pp.165-174
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• 2006

Data dissemination using either flooding or legacy ad-hoc routing protocol is not realistic approach in the wireless sensor networks, which are composed of sensor nodes with very weak computing power, small memory and limited battery. In this paper, we propose the ELF(Energy-efficient Localized Flooding) protocol. The ELF is energy-efficient data dissemination protocol for wireless sensor networks. In the ELF protocol, there are two data delivery phases between fixed source and mobile sink node. The first phase, before the tracking zone, sensing data are forwarded by unicasting. After that, within the tracking zone, sensing data are delivered by localized flooding. Namely, the ELF Properly combines advantages from both unicasting and flooding. According to evaluation results by simulation, the proposed ELF protocol maintains very high data delivery ratio with using a little energy. Also, the property of average delay is better than others. From our research results, the ELF is very effective data dissemination protocol for wireless sensor networks.

• Journal of KIISE:Information Networking
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• v.33 no.4
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• pp.310-323
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• 2006

In this paper, we describe a secure cluster-routing protocol based on a multi-layer scheme in ad hoc networks. We propose efficient protocols, Authentication based on Multi-layer Clustering for Ad hoc Networks (AMCAN), for detailed security threats against ad hoc routing protocols using the selection of the cluster head (CH) and control cluster head (CCH) using a modification of cluster-based routing ARCH and DMAC. This protocol provides scalability of Shadow Key using threshold authentication scheme in ad hoc networks. The proposed protocol comprises an end-to-end authentication protocol that relies on mutual trust between nodes in other clusters. This scheme takes advantage of Shadow Key using threshold authentication key configuration in large ad hoc networks. In experiments, we show security threats against multilayer routing scheme, thereby successfully including, establishment of secure channels, the detection of reply attacks, mutual end-to-end authentication, prevention of node identity fabrication, and the secure distribution of provisional session keys using threshold key configuration.

• Journal of Satellite, Information and Communications
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• v.6 no.1
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• pp.75-79
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• 2011

Wireless devices can communicate between each other without existing infrastructure in mobile Ad-hod network. Ad hoc networks can be used under difficult conditions, where it is difficult to construct infrastructures, such as shadowing areas, disaster areas, war area, and so on. In order to support to considerable and various wireless services, more spectrum resources are needed. However, efficient utilization of the frequency resource is difficult because of spectrum scarcity and the conventional frequency regulation. Ad-hoc networks employing cognitive radio (CR) system that guarantee high spectrum utilization provide effective way to increase the network capacity. In this paper, we simulate and compare the performance of conventional single and cooperative spectrum sensing with CR system using ad-hoc networks in additive white Gaussian noise (AWGN) and Rayleigh channel model. And we demonstrate performance improvement by analyzing the system performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.10
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• pp.2237-2246
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• 2010

In this paper, the performance of a RCO-MAC protocol is evaluated using a different traffic model. Data frames are assumed to generate based on an exponential distribution from one source node and then directly to be stored into the input buffer in the source node. System throughput, average access delay and average system delay are used as a performance measure. Performance evaluation is carried out by the computer simulation. Numerical results show that the RCO-MAC scheme offers 18% higher system throughput than the rDCF scheme. In addition, the numerical results show that the RCO-MAC protocol also offers the better average system delay under any traffic load than that by the rDCF scheme, which was not obtained in the previous research due to the saturated traffic model.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.7
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• pp.51-57
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• 2012

This paper proposes a group key design based on ECDH(Elliptic Curve Diffie Hellman) which guarantees secure V2V and V2I communication. The group key based on ECDH generates the VGK(Vehicular Group key) which is a group key between vehicles, the GGK(Global Group Key) which is a group key between vehicle groups, and the VRGK(Vehicular and RSU Group key) which is a group key between vehicle and RSUs with ECDH algorithm without an AAA server being used. As the VRGK encrypted with RGK(RSU Group Key) is transferred from the current RSU to the next RSU through a secure channel, a perfect forward secret security is provided. In addition, a Sybil attack is detected by checking whether the vehicular that transferred a message is a member of the group with a group key. And the transmission time of messages and the overhead of a server can be reduced because an unnecessary network traffic doesn't happen by means of the secure communication between groups.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.10
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• pp.977-985
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• 2012

Recently, many countries have been developing new protocols to improve the performance of tactical ad hoc networks for implementing NCW (Network Centric Warfare). Combat net radio (CNR) networks are the most important communication infra for the ground forces such as infantry of Army. U.S. Army had developed MIL-STD-188-220D that is the Interoperability Standard for DMTDs (Digital Messages Transfer Device Subsystems) for voice and data communication in CNR. MIL-STD-188-220D is a candidate for MAC protocol of TMMR which is next radio and has a few constraints to used in TMMR. NAD (Network Access Delay) defined in MIL-STD-188-220D needs time synchronization to avoid collision. However, it is difficult for time synchronization to fit in multi-hop environment. We suggest the enhanced DAP (Deterministic Adaptable Priority)-NAD to prevent conflicts and decrease delays in multi-hop CNR. Simulation results show that the proposed scheme improves the performance in multi-hop CNR networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.10
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• pp.2309-2315
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• 2013

VANET(Vehicular Ad-hoc Network) is getting attention as an application to improve driver safety through inter-vehicle communication. For activation of VANET, privacy-preserving mutual authentication has to be guaranteed. In previous works, authors proposed various group-based authentication protocols. However, risks on ID exposure due to repeated use of group key and RSU(Road Side Unit) DoS attack were not considered. In this paper, we propose a probabilistic approach for robust anonymous authentication protocol. We evaluated our proposed method in a sets of criteria in VANET and verified it is an efficient solution for enhancing privacy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.11
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• pp.1148-1161
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• 2012

Recently, developments in the field of communication and network technologies induced new paradigm in the defense weapon system. As a consequence, military authorities develop the Tactical Information Communication Network(TICN) system to adapt to the changing paradigm. One of the most important functions of TICN is real-time communication. As a result, TICN system needs to receive real-time information from the battlefield, and the key technology to support these features is MANET(Mobile Ad-Hoc Network) routing protocol. In this paper, we analyze problems of the shortest path scheme in tactical Ad-Hoc networks, which is widely used in common Ad-Hoc networks. We propose efficient routing protocol for tactical MANET by considering the environment of small combat units, such as node position, speed and data size. The proposed algorithm shows reliable data transfer and low latency in battlefield.

• Journal of the Korea Society of Computer and Information
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• v.19 no.6
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• pp.81-92
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• 2014

In this paper, we propose an efficient dynamic workload balancing strategy which improves the performance of high-performance computing system. The key idea of this dynamic workload balancing strategy is to minimize execution time of each job and to maximize the system throughput by effectively using system resource such as CPU, memory. Also, this strategy dynamically allocates job by considering demanded memory size of executing job and workload status of each node. If an overload node occurs due to allocated job, the proposed scheme migrates job, executing in overload nodes, to another free nodes and reduces the waiting time and execution time of job by balancing workload of each node. Through simulation, we show that the proposed dynamic workload balancing strategy based on CPU, memory improves the performance of high-performance computing system compared to previous strategies.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.781-783
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• 2014

Mobile ad hoc network(MANET) consists of node that has mobility. MANET has increased overhead that caused by frequent topology changes. For reducing overhead, hierarchical network that communicates through cluster head node has been researched. When traffic is concentrated on cluster head node, cluster member node can't send message. To solve this problem, we proposed Step Parent algorithm. Proposed algorithm, cluster member node checks traffic of cluster head node using route path of other cluster head node in efficient coverage area. When cluster head node has increased traffic, cluster member node make a new route path by route path by routing path to another cluster head node. So cluster member node sends a message to destination node, we check improving delivery ratio.