• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.5
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• pp.1089-1095
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• 2004

The genetic algorithms have been used to take a near optimal solution because The generation of the optimal Steiner tree from a given network is NP-hard problem,. The chromosomes in genetic algorithm are represented with the floating point representation instead of the existing binary string for solving this problem. A spanning tree was obtained from a given network using Prim's algorithm. Then, the new Steiner point was computed using genetic algorithm with the chromosomes in the floating point representation, and it was added to the tree for approaching the result. After repeating these evolving steps, the near optimal Steiner tree was obtained. Using this method, the tree is quickly and exactly approached to the near optimal Steiner tree compared with the existing genetic algorithms using binary string.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.136-138
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• 2002

관계형 OLAP 시스템에서는 다차원 분석에 사용될 데이터를 하나의 사실과 여러 개의 차원 테이블로 구성된 스타 스키마로 표현한다. 사실 테이블은 측정치의 속성을 포함하며, 차원 테이블들은 이러한 사실 테이블에서 중심으로 뻗어져 나온 형태로써, 측정치에 대한 정보를 제공한다. 방대한 크기의 OLTP 소스 데이타베이스로부터 사실과 차원 테이블로 구성된 스타 스키마 설계하기 위해서는 풍부한 경험과 많은 시간을 필요로 한다. 따라서 스타 스키마를 효과적으로 설계하기 위한 체계적인 설계 방법이 필요하다. 본 논문에서는 소스 데이터베이스들에 대한 개념적 모델인 ER 도형을 이용하여 여러 개의 사실 엔터티를 추출하는 알고리즘과 이를 통해 자동적으로 스타 스키마를 설계하는 알고리즘을 제시하였다. 스타 스키마가 하나의 사실 테이블에 여러 개의 차원 테이블이 M:1의 관계로 연결되었다는 성질을 활용하여, 이 방법에서는 EH 도형이 연결된 위상 구조를 이용하여 각 엔터티에 연결된 M:1 관계의 개수에 근거하여 사실과 차원을 추출하는 방법을 제시하였다. 본 논문에는 이러한 방법을 통해 데이터 웨어하우스의 스타 스키마들 자동적으로 쉽게 설계하여 소요되는 시간과 노력을 줄일 수 있도록 하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1110-1115
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• 2014

The matrix-star and the transposition graphs are considered as star graph variants that have various merits in graph theory such as node symmetry, fault tolerance, recursive scalability, etc. This paper describes an one-to-one mapping algorithm from a matrix-star graph to a transposition graph using adjacent properties in graph theory. The result show that a matrix-star graph $MS_{2,n}$ can be embedded in a transposition graph $T_{2n}$ with dilation n or less and average dilation 2 or less.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05a
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• pp.359-362
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• 2003

본 논문에서는 멀티캐스팅 경로 설정에 많이 사용되는 스타이너 트리 문제를 위한 새로운 유전자 알고리즘을 제안하였다. 제안된 알고리즘에서는 휴리스틱 방법으로 스타이너 트리를 구성하고, 여기에 유전자 알고리즘을 반복 수행하여, 보다 최적에 가까운 스타이너 트리를 구하도록 하였다. 제안 알고리즘을 OR- 라이브러리의 스타이너 트리 문제 중 38개의 예제에 대하여 실험한 결과, 21개의 예제에서 최적 해를 찾아내었다. 또한 반복 계산 초기에 빠르게 수렴하는 성질을 볼 수 있었다.

• The KIPS Transactions:PartA
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• v.15A no.6
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• pp.345-350
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• 2008

Recently, a HyperStar network HS(2n,n) has been introduced as a new interconnection network of new topology for parallel processing. HyperStar network has properties of hypercube and star graph, further improve the network cost of a hypercube with the same number of nodes. In this paper, we show a construction algorithm of edge-disjoint spanning trees in HyperStar network HS(2n,n). Also, we prove that edge-disjoint spanning tree by the algorithm is optimal.

• The KIPS Transactions:PartA
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• v.16A no.4
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• pp.299-306
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• 2009

Hierarchical Folded HyperStar Network has lower network cost than HCN(n,n) and HFN(n,n) which are hierarchical networks with the same number of nodes. In this paper, we analyze embedding between Hierarchical Folded HyperStar HFH($C_n,C_n$) and Hypercube, HCN(n,n), HFN(n,n). The results of embedding are that HCN(n,n), HFN(n,n) and Hypercube $Q_{2n}$ can be embedded into HFH($C_n,C_n$) with expansion $\frac{C^n}{2^{2n}}$ and dilation 2, 3, and 4, respectively. Also, HFH($C_n,C_n$) can be embedded into HFN(2n,2n) with dilation 1. These results mean so many developed algorithms in Hypercube, HCN(n,n), HFN(n,n) can be used efficiently in HFH($C_n,C_n$).

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.4
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• pp.430-436
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• 2014

Matrix-star and Half-Pancake graphs are modified versions of Star graphs, and has some good characteristics such as node symmetry and fault tolerance. This paper analyzes embedding between Matrix-star and Half-Pancake graphs. As a result, Matrix-star graphs $MS_{2,n}$ can be embedded into Half-Pancake graphs $HP_{2n}$ with dilation 5 and expansion 1. Also, Half Pancake Graphs, $HP_{2n}$ can be embedded into Matrix Star Graphs, $MS_{2,n}$ with the expansion cost, O(n). This result shows that algorithms developed from Star Graphs can be applied at Half Pancake Graphs with additional constant cost because Star Graphs, $S_n$ is a part graph of Matrix Star Graphs, $MS_{2,n}$.

• The KIPS Transactions:PartA
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• v.15A no.2
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• pp.95-100
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• 2008

In this paper, we propose a new interconnection network topology, hierarchical folded hyper-star network HFH($C_n,\;C_n$), which is based on folded hyper-star network. Our results show that the proposed hierarchical folded hyper-star network performs very competitively in comparison to folded hyper-star network and hierarchical network HCN(m,m), HFN(m,m) have been previously proposed, when diameter ${\times}$ degree is used as a network cost measure. We also investigate various topological properties of HFH($C_n,\;C_n$) including connectivity, routing algorithm, diameter, broadcasting.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.2
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• pp.65-74
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• 2002

Recently star networks are considered as attractive alternatives to the widely used hypercube for interconnection networks in parallel processing systems by many researchers. One of the fundamental communication problems on star graph networks is broadcasing In this paper we consider the broadcasting problems in star graph networks using wormhole routing. In wormhole routed system minimizing link contention is more critical for the system performance than the distance between two communicating nodes. We use Hamiltonian paths in star graph to set up link-disjoint communication paths We present a broadcast algorithm in n-dimensional star graph of N(=n!) nodes such that the total completion time is no larger than $([long_n n!]+1)$ steps where $([long_n n!]+1)$ is the lower bound This result is significant improvement over the previous n-1 step broadcasting algorithm.

• The Journal of Korean Association of Computer Education
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• v.17 no.2
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• pp.115-124
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• 2014

Hypercube and star graph are widely known as interconnection network. The embedding of an interconnection network is a mapping of a network G into other network H. The possibility of embedding interconnection network G into H with a low cost, has an advantage of efficient algorithms usage in network H, which was developed in network G. In this paper, we provide an embedding algorithm between HCN and HON. HCN(n,n) can be embedded into HON($C_{n+1},C_{n+1}$) with dilation 3 and HON($C_d,C_d$) can be embedded into HCN(2d-1,2d-1) with dilation O(d). Also, star graph can be embedded to half pancake's value of dilation 11, expansion 1, and average dilation 8. Thus, the result means that various algorithms designed for HCN and Star graph can be efficiently executed on HON and half pancake, respectively.