• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.10
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• pp.3439-3457
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• 2014

Clustering is an effective method for improving the performance of large scale mobile ad hoc networks. However, when the moving speed is very fast, the topology changes quickly, which leads to frequent cluster topology updates. The drastically increasing control overheads severely threaten the throughput of the network. SCBCS (Signal Characteristic Based Cluster Scheme) is proposed as a method to potentially reduce the control overheads caused by cluster formation and maintenance in aeronautical ad hoc networks. Each node periodically broadcasts Hello packets. The Hello packets can be replaced by data packets, which preserve bandwidth. The characteristics of the received packets, such as the Doppler shift and the power of two successive Hello packets, help to calculate the relative speed and direction of motion. Then, the link connection lifetime is estimated by the relative speed and direction of motion. In the clustering formation procedure, the node with the longest estimated link connection time to its one-hop neighbors is chosen as the cluster head. In the cluster maintenance procedure, re-affiliation and re-clustering schemes are designed to keep the clusters more stable. The re-clustering phenomenon is reduced by limiting the ripple effect. Simulations have shown that SCBCS prolongs the link connection lifetime and the cluster lifetime, which can reduce the topology update overheads in highly dynamic aeronautical ad hoc networks.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.31-34
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• 2012

In MANET, frequent movement of nodes causes the dynamic network topology changes. Therefore the routing protocol, which is very stable to effectively respond the changes of the network changes, is required. Moreover, the existing cluster-based routing protocol, that is the hybrid approach, has routing delay due to the re-electing of the cluster header. In addition, the routing table of CBRP has all only one hop distant neighbor nodes. PCBRP, proposed in this paper, ties two clusters in one pair of clusters to make longer radius. Then the pair of the cluster headers manages and operates corresponding member nodes. When they route nodes in the paired cluster internally, PCBRP reduces the delay by requesting a route. Therefore PCBRP shows improved total delay of the network and improved performance of packet transmitting rate.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.5
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• pp.799-818
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• 2010

In traditional unstructured P2P file sharing network, each peer establishes connections with a certain number of randomly chosen other peers. This would lead to redundant traffic and P2P network partition in mobile ad hoc network (MANET). We propose an approach to construct an efficient unstructured P2P overlay over MANET using underlying cluster-based routing (CBRP). One of the peers in the P2P network is used as a root-peer to connect all peers. Each peer maintains connection with physically closer peers such that it can reach the root-peer. The peer constructs a minimum-spanning tree consisting of itself, its directly connected neighbor peers and 2-hop away neighbor peers to remove far away redundant links and to build an overlay closer to the physical network. Due to on-demand nature of inter-cluster routing of CBRP, the positioning algorithm for MANET is used to retrieve the file by a peer from the source peer via shorter path in the physical network. We can show by simulation that our approach performs better in comparison with the existing approach.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.2
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• pp.13-18
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• 2011

Security supports are a significant factor in mobile ad hoc networks. Especially in dynamic topologies, considering cluster, key management is essential to provide a secure system. Recently, Li-Liu proposed iD-based multiple key management scheme for cluster-based ad hoc networks. However, we found the security weakness of their scheme. In this paper, we analyze the security of Li-Liu's scheme and show that master secret key and fragment of the master secret key can be revealed to compromised CHs and nodes. Furthermore, we propose a solution to improve the scheme against disclosure of the share key and the master secret key even though system parameters are opened to compromised nodes and modify the Li-Liu's scheme fitted for a scalable networks. The improved IMKM scheme could be usefully applied in dynamic cluster-based MANETs such as the military battlefields, mobile marketplace and VANETs.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.5
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• pp.1963-1978
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• 2015

With the advancement of mobile web environments, identification and analysis of the user behavior play a significant role and remains a challenging task to implement with variations observed in the model. This paper presents an efficient method for mining optimized user behavior prediction model using genetic algorithm on mobile web structure. The framework of optimized user behavior prediction model integrates the temporary and permanent register information and is stored immediately in the form of integrated logs which have higher precision and minimize the time for determining user behavior. Then by applying the temporal characteristics, suitable time interval table is obtained by segmenting the logs. The suitable time interval table that split the huge data logs is obtained using genetic algorithm. Existing cluster based temporal mobile sequential arrangement provide efficiency without bringing down the accuracy but compromise precision during the prediction of user behavior. To efficiently discover the mobile users' behavior, prediction model is associated with region and requested services, a method called optimized user behavior Prediction Model using Genetic Algorithm (PM-GA) on mobile web structure is introduced. This paper also provides a technique called MAA during the increase in the number of models related to the region and requested services are observed. Based on our analysis, we content that PM-GA provides improved performance in terms of precision, number of mobile models generated, execution time and increasing the prediction accuracy. Experiments are conducted with different parameter on real dataset in mobile web environment. Analytical and empirical result offers an efficient and effective mining and prediction of user behavior prediction model on mobile web structure.

• International Journal of Computer Science & Network Security
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• v.23 no.1
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• pp.11-16
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• 2023

Vehicular networks are part of the next generation wireless and smart Intelligent Transportation Systems (ITS). In the future, autonomous vehicles will be an integral part of ITS and will provide safe and reliable traveling features to the users. The reliability and security of data transmission in vehicular networks has been a challenging task. To manage data transmission in vehicular networks, road networks are divided into clusters and a cluster head is selected to handle the data. The selection of cluster heads is a challenge as vehicles are mobile and their connectivity is dynamically changing. In this paper, a novel secure cluster head selection algorithm is proposed for secure and reliable data sharing. The idea is to use the secrecy rate of each vehicle in the cluster and adaptively select the most secure vehicle as the cluster head. Simulation results show that the proposed scheme improves the reliability and security of the transmission significantly.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.417-420
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• 2000

The purpose of this paper is to design the menu of mobile phone based on the impression engineering. Free response survey analysis was used to collect impression data on mobile phone functions with time interval. Simultaneity analysis was applied to finding the relationship among selected impression. We cluster the related impression so as to design the menu of a mobile phone accordingly. This research is expected to contribute to the improvement of customer satisfaction by reflecting customer's impression in the process of product design.

• Journal of Korean Institute of Industrial Engineers
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• v.26 no.4
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• pp.431-438
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• 2000

The purpose of this paper is to design the menu of mobile phone based on the impression engineering. Free response survey analysis was used to collect impression data on mobile phone functions with time interval. Simultaneity analysis was applied to finding the relationship among selected impression. We cluster a set of the related impression so as to design the menu of a mobile phone accordingly. This research is expected to contribute to the improvement of customer satisfaction by reflecting customer's impression in the process of product design.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.5B
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• pp.721-733
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• 2010

In this paper, we propose a scalable content-based routing scheme for the tactical mobile ad-hoc networks where the nodes usually move together forming a group. Our scheme is classified as a content-based routing scheme based on publish and subscribe model. The nodes compose a cluster according to their position and interest. Our scheme allows multi-level cluster nesting. As a publish/subscribe model does, each node announces its interest to the cluster head who aggregates and announces the interests from cluster members to its neighbor cluster head. Actual data messages are delivered to the end node via cluster header in the reverse direction of the interest announcement. Using Qualnet simulator, we evaluated the performance of our scheme in comparison with two well-known content-based routing schemes. Simulation results show that our scheme maintains higher message delivery ratio as number of nodes increases whereas the two schemes show much lower delivery ratio. In addition, as the group mobility gets faster our scheme incurs less or similar control message overhead compared with the two schemes.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.17-20
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• 2008

A clustering scheme for ad hoc networks is aimed at managing a number of mobile devices by utilizing hierarchical structure of the networks. In order to construct and maintain an effective hierarchical structure in ad hoc networks where mobile devices may move at high mobility, the following requirements must be satisfied. The role of each mobile device for the hierarchical structure is adaptive to dynamic change of the topology of the ad hoc networks. The role of each mobile device should thus change autonomously based on the local information. The overhead for management of the hierarchical structure is small. The number of mobile devices in each cluster should thus be almost equivalent. This paper proposes an adaptive multihop clustering scheme for highly mobile ad hoc networks. The results obtained by extensive simulation experiments show that the proposed scheme does not depend on mobility and node degree of mobile devices in the ad hoc network, which satisfy the above requirements.