• KIPS Transactions on Software and Data Engineering
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• v.4 no.1
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• pp.37-44
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• 2015

In traditional social network analysis, the betweenness centrality measure has been heavily used to identify the relative importance of nodes. Since the time complexity to calculate the betweenness centrality is very high, however, it is difficult to get it of each node in large-scale social network where there are so many nodes and edges. In our past study, we defined a new type of network, called the expanded ego network, which is built only with each node's local information, i.e., neighbor information of the node's neighbor nodes, and also defined a new measure, called the expanded ego betweenness centrality. In this paper, We propose algorithm that quickly computes expanded ego betweenness centrality by exploiting structural properties of expanded ego network. Through the experiment with virtual network used Barab$\acute{a}$si-Albert network model to represent the generic social network and facebook network to represent actual social network, We show that the node's importance rank based on the expanded ego betweenness centrality has high similarity with that the node's importance rank based on the existing betweenness centrality. We also show that the proposed algorithm computes the expanded ego betweenness centrality quickly than existing algorithm.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.5
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• pp.209-216
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• 2013

In traditional social network analysis, the betweenness centrality measure has been heavily used to identify the relative importance of nodes in terms of message delivery. Since the time complexity to calculate the betweenness centrality is very high, however, it is difficult to get it of each node in large-scale social network where there are so many nodes and edges. In this paper, we define a new type of network, called the expanded ego network, which is built only with each node's local information, i.e., neighbor information of the node's neighbor nodes, and also define a new measure, called the expended ego betweenness centrality. Through the intensive experiment with Barab$\acute{a}$si-Albert network model to generate the scale-free networks which most social networks have as their embedded feature, we also show that the nodes' importance rank based on the expanded ego betweenness centrality has high similarity with that based on the traditional betweenness centrality.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.4
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• pp.441-450
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• 2016

Wireless multi-hop communication is one of the key technologies to operate Unmanned Ground System (UGS) networks efficiently. Conventionally a lot of routing protocol has been developed and studied for multi-hop networks like Mobile Ad-hoc Network (MANET). However, the routing protocol for the unique environment of the UGS requires further studies, since conventional routing protocols cannot be used itself for UGS networks. In this paper, we propose the Betweenness Centrality based Geographic Routing (BCGR) which considers the main function of UGS. BCGR utilizes expanded ego betweenness centrality, mobility and location information error, respectively. We have conducted a simulation study for evaluating the performance of the BCGR using ns-3, and our simulation results show that BCGR outperforms the conventional routing protocols such as AODV and GPSR in terms of end-to-end transmission reliability, throughput and delay.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.1
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• pp.15-22
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• 2014

Delay-Tolerant Network employs message forwarding based on a Store, Carry and Forward method to conquer no guarantee of continue connectivity. For this reason, a lot of DTN routing scheme have been proposed recently. message forwarding is an important research issue in delay-tolerant network and In this paper, we propose a efficiency DTN routing scheme using node's social relation and expanded Ego-network betweenness centrality. Our simulation results show that it is more efficient to message delivery cost than Epidemic routing, Friendship routing while it has a little performance degradation of message delivery ratio.