• Journal of the Korea Society of Computer and Information
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• v.19 no.7
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• pp.131-140
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• 2014

In this paper, we present an efficient implementation of Kruskal's algorithm to obtain a minimum spanning tree. The proposed method utilizes the union-find data structure, reducing the depth of the tree of the node set by making the nodes in the path to root be the child node of the root of combined tree. This method can reduce the depth of the tree by shortening the path to the root and lowering the level of the node. This is an efficient method because if the tree's depth reduces, it could shorten the time of finding the root of the tree to which the node belongs. The performance of the proposed method is evaluated through the graphs generated randomly. The results showed that the proposed method outperformed the conventional method in terms of the depth of the tree.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.51-59
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• 2014

This paper suggests a method of lessening number of a graph's edges population in order to rapidly obtain the minimum spanning tree. The present minimum spanning tree algorithm works on all the edges of the graph. However, the suggested algorithm reduces the edges population size by means of applying a method of deleting maximum weight edges in advance from vertices with more than 2 valencies. Next, it applies a stopping criterion which ideally terminates Borůvka, Prim, Kruskal and Reverse-Delete algorithms for reduced edges population. On applying the suggested algorithm to 9 graphs, it was able to minimize averagely 83% of the edges that do not become MST. In addition, comparing to the original graph, edges are turned out to be lessened 38% by Borůvka, 37% by Prim, 39% by Kruskal and 73% by Reverse-Delete algorithm, and thereby the minimum spanning tree is obtained promptly.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.103-114
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• 2013

This paper suggests a method to reduce the number of performances of Kruskal and Reverse-delete algorithms. Present Kruskal and Reverse-delete algorithms verify whether the cycle occurs within the edges of the graph. For this reason, they have problems of unnecessarily performing extra algorithms from the edges, even though they've already obtained the minimum spanning tree. This paper, first of all, suggests the 1st method which reduces the no. of performances by introducing stop point criteria of algorithm, but at the same time, performs algorithms from all the edges, just like how Kruskal and Reverse-delete algorithms. Next, it suggests the 2nd method which finds the minimum spanning tree from the remaining edges after getting rid of all the unnecessary edges which are considered not to affect the minimum spanning tree. These suggested methods have an effect of terminating algorithm at least 1.4 times and at most 3.86times than Kruskal and Reverse-delete algorithms, when applied to the real graphs. We have found that the 2nd method of the Reverse-delete algorithm has the fastest speed in terminating an algorithm, among 4 algorithms which are results of the 2 suggested methods being applied to 2 algorithms.

• Journal of the Korea Society of Computer and Information
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• v.20 no.5
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• pp.31-39
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• 2015

The degree-constrained minimum spanning tree (d-MST) problem is considered NP-complete for no exact solution-yielding polynomial algorithm has been proposed to. One thus has to resort to an heuristic approximate algorithm to obtain an optimal solution to this problem. This paper therefore presents a polynomial time algorithm which obtains an intial solution to the d-MST with the help of Kruskal's algorithm and performs k-opt on the initial solution obtained so as to derive the final optimal solution. When tested on 4 graphs, the algorithm has successfully obtained the optimal solutions.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.417-418
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• 2012

최소 신장 트리를 이용하여 멀티미디어 통신을 위한 네트워크를 구축하는 것보다 효과적인 유클리드 스타이너 트리 생성과정에서 필연적으로 발생되는 막대한 계산 량과 실행시간 문제를 해결하기 위해 Delaunay 삼각망을 적용하는 방법을 제안한다.

• Journal of KIISE:Information Networking
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• v.30 no.3
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• pp.424-436
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• 2003

In this paper, we propose the Centroid-based Backbone Core Tree(CBCT) generation algorithm for the shared tree-based IP multicasting. The proposed algorithm is based on the Core Based Tree(CBT) protocol. Despite the advantages over the source-based trees in terms of scalability, the CBT protocol still has the following limitations; first, the optimal core router selection is very difficult, and second, the multicast traffic is concentrated near a core router. The Backbone Core Tree(BCT) protocol, as an extension of the CBT protocol has been proposed to overcome these limitations of the CBT Instead of selecting a specific core router for each multicast group, the BCT protocol forms a backbone network of candidate core routers which cooperate with one another to make multicast trees. However, the BCT protocol has not mentioned the way of selecting candidate core routers and how to connect them. The proposed CBCT generation algorithm employs the concepts of the minimum spanning tree and the centroid. For the performance evaluation of the proposed algorithm, we showed the performance comparison results for both of the CBT and CBCT protocols.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.214-216
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• 2002

본 논문에서는 many-to-many IP 멀티캐스팅을 위한 효율적인 Backbone Core Tree(BCT)생성 알고리즘에 대하여 제안한다. 본 논문의 제안기법은 Core Based Tree(CBT)에 기반을 두고 있다. CBT는 공유 트리를 이용하여 멀티캐스트 자료를 전달하기 때문에 Source Based Tree에 비하여 각 라우터가 유지해야 하는 상태 정보의 양에 적고 적용하기 간단하지만, Core 라우터 선택의 어려움과 트래픽이 Core로 집중되는 문제점을 가지고 있다. 이에 대한 보완책으로 Backbone Core Tree기법이 제안되었는데, 본 논문에서는 주어진 네트워크 위상 그래프에서 최소신장 트리를 만들고, 센트로이드를 이용하여 효율적인 BCT를 생성하는 알고리즘을 제안한다.

• Proceedings of the Korea Society for Simulation Conference
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• 2002.05a
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• pp.67-71
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• 2002

본 논문에서는 many-to-many IP 멀티캐스팅을 위한 효율적인 BCT(Backbone Core Tree)생성 알고리즘의 시뮬레이션 방법에 대하여 제안한다. BCT는 기법은 CBT(Core Based Tree)에 기반을 두고 있다. CBT는 공유 트리를 이용하여 멀티캐스트 자료를 전달하기 때문에 Source based Tree에 비하여 각 라우터가 유지해야 하는 상태 정보의 양에 적고, 적용하기 간단하지만, Core 라우터 선택의 어려움과 트래픽이 Core로 집중되는 문제점을 가지고 있다. 이에 대한 보완책으로 BCT기법이 제안되었는데, 본 논문에서는 주어진 네트워크 위상 그래프에서 최소신장 트리를 만들고, 센트로이드(Centroid)를 이용하여 효율적인 BCT를 생성하는 알고리즘을 제안하고 시뮬레이션 방법을 제시한다.

• The KIPS Transactions:PartA
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• v.18A no.5
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• pp.215-224
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• 2011

In this paper, a mechanism connecting all weighted migration routes with minimum cost with EGOSST is proposed. Weighted migration routes may be converted to weighted input edges considered as not only traces but also traffics or trip frequencies of moving object on communication lines, roads or railroads. Proposed mechanism can be used in more wide and practical area than mechanisms considering only moving object traces. In our experiments, edge number, maximum weight for input edges, and detail level for grid are used as input parameters. The mechanism made connection cost decrease average 1.07% and 0.43% comparing with the method using weight minimum spanning tree and weight steiner minimum tree respectively. When grid detail level is 0.1 and 0.001, while each execution time for a connecting solution increases average 97.02% and 2843.87% comparing with the method using weight minimum spanning tree, connecting cost decreases 0.86% and 1.13% respectively. This shows that by adjusting grid detail level, proposed mechanism might be well applied to the applications where designer must grant priority to reducing connecting cost or shortening execution time as well as that it can provide good solutions of connecting migration routes with weights.

• 한국벤처창업학회:학술대회논문집
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• 2010.08a
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• pp.71-89
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• 2010

It is strongly believed that multicast will become one of the most promising services on internet for the next generation. Multicast service can be deployed either on network-layer or application-layer. IP multicast (network-layer multicast) is implemented by network nodes (i.e., routers) and avoids multiple copies of the same datagram on the same link. Despite the conceptual simplicity of IP multicast and its obvious benefits, it has not been widely deployed since there remain many unresolved issues. As an alternative to IP multicast, overlay multicast (application-layer multicast) implements the multicast functionality at end hosts rather than routers. This may require more overall bandwidth than IP multicast because duplicate packets travel the same physical links multiple times, but it provides an inexpensive, deployable method of providing point-to-multipoint group communication. In this paper we develop an efficient method applied greedy algorithm for solving two models of overlay multicast tree building problem that is aimed to construct MDST (Minimum Diameter Spanning Tree : minimum cost path from a source node to all its receivers) and MST (Minimum Spanning Tree : minimum total cost spanning all the members). We also simulate and analyze MDST and MST.