• The KIPS Transactions:PartA
• /
• v.17A no.5
• /
• pp.213-220
• /
• 2010

In this paper, a mechanism connecting all input edges with minimum length through Steiner tree is proposed. Edges are convertible into communication lines, roads, railroads or trace of moving object. Proposed mechanism could be applied to connect these edges with minimum cost. In our experiments where input edge number and maximum connections per edge are used as input parameters, our mechanism made connection length decrease average 6.8%, while building time for a connecting solution increase average 192.0% comparing with the method using minimum spanning tree. The result shows our mechanism might be well applied to the applications where connecting cost is more important than building time for a connecting solution.

• Journal of the Korea Society of Computer and Information
• /
• v.19 no.1
• /
• pp.57-64
• /
• 2014

As Steiner minimum tree building belongs to NP-Complete problem domain, heuristics for the problem ask for immense amount execution time and computations in numerous inputs. In this paper, we propose an efficient mechanism of euclidean Steiner minimum tree construction for numerous inputs using combination of Delaunay triangulation and Prim's minimum spanning tree algorithm. Trees built by proposed mechanism are compared respectively with the Prim's minimum spanning tree and minimums spanning tree based Steiner minimum tree. For 30,000 input nodes, Steiner minimum tree by proposed mechanism shows about 2.1% tree length less and 138.2% execution time more than minimum spanning tree, and does about 0.013% tree length less and 18.9% execution time less than minimum spanning tree based Steiner minimum tree in experimental results. Therefore the proposed mechanism can work moderately well to many useful applications where execution time is not critical but reduction of tree length is a key factor.

• The KIPS Transactions:PartA
• /
• v.16A no.6
• /
• pp.509-518
• /
• 2009

In this paper, a mechanism that produces an approximation edges minimum spanning tree swiftly using virtual nodes called portals dividing given edges into same distance sub-edges. The approximation edges minimum spanning tree can be used in many useful areas as connecting communication lines, road networks and railroad systems. For 3000 random input edges, when portal distance is 0.3, tree building time decreased 29.74% while the length of the produced tree increased 1.8% comparing with optimal edge minimum spanning tree in our experiment. When portal distance is 0.75, tree building time decreased 39.96% while the tree length increased 2.96%. The result shows this mechanism might be well applied to the applications that may allow a little length overhead, but should produce an edge connecting tree in short time. And the proposed mechanism can produce an approximation edge minimum spanning tree focusing on tree length or on building time to meet user requests by adjusting portal distance or portal discard ratio as parameter.

• Journal of the Korea Society of Computer and Information
• /
• v.17 no.7
• /
• pp.87-95
• /
• 2012

In this paper, PTAS three-dimensional Steiner minimum tree connecting numerous input nodes rapidly in 3D space is proposed. Steiner minimum tree problem belongs to NP problem domain, and when properly devised heuristic introduces, it is generally superior to other algorithms as minimum spanning tree affiliated with P problem domain. But when the number of input nodes is very large, the problem requires excessive execution time. In this paper, a method using PTAS is proposed to solve the difficulty. In experiments for 70,000 input nodes in 3D space, the tree produced by the proposed 8 space partitioned PTAS method reduced 86.88% execution time, compared with the tree by naive 3D steiner minimum tree method, though increased 0.81% tree length. This affirms the proposed method can work well for applications that many nodes of three dimensions are need to connect swifty, enduring slight increase of tree length.

• Journal of Korean Society of Transportation
• /
• v.24 no.6 s.92
• /
• pp.75-85
• /
• 2006

Recently. large number of countires have been focused on the construction of container seaport and hub airport to enrole as the center of logistics. In particular, the East Asian nations have been enhanced their airports' facilities in order to accommodate for demand of global market environment. In Korea, Incheon International Airport (ICN) was opened in 2001 to take leading role as the Northeast Asian main hub airport. The purpose of this research is to analyze the transferring connectivity at ICN. To analyze its connectivity, this research has been applies two methodologies ; wane structure and minimum or maximun connection time analysis It has analyzed the temporal configuration as the frequency and quality of indirect connections offered by an airline by adopting a wave-system structure in the airline flight schedule. As an empirical analysis, it also calculated the minimum and maximum connection time adopting Korean Air's flight information.

• The KIPS Transactions:PartA
• /
• v.17A no.2
• /
• pp.103-112
• /
• 2010

Cluster sensor network is a sensor network where input nodes crowd densely around some nuclei. Steiner minimum tree is a tree connecting all input nodes with introducing some additional nodes called Steiner points. This paper proposes a mechanism for efficient construction of a cluster sensor network connecting all sensor nodes and base stations using connections between nodes in each belonged cluster and between every cluster, and using repetitive constructions of approximate Steiner minimum trees. In experiments, while taking 1170.5% percentages more time to build cluster sensor network than the method of Euclidian minimum spanning tree, the proposed mechanism whose time complexity is O($N^2$) could spend only 20.3 percentages more time for building 0.1% added length network in comparison with the method of Euclidian minimum spanning tree. The mechanism could curtail the built trees' average length by maximum 3.7 percentages and by average 1.9 percentages, compared with the average length of trees built by Euclidian minimum spanning tree method.

• The Korean Journal of Air & Space Law and Policy
• /
• v.22 no.2
• /
• pp.85-108
• /
• 2007

동북아시아지역에서 인천국제공항이 최고의 허브공항으로서 역할을 위해서는 무엇보다도 환승율에 대한 연구가 필요하다고 판단된다. 인천국제공항은 2005년도에 3,054,485만명의 환승여객을 처리하여 환승율은 11.9% 를 기록하였는데 이는 동북아시아의 경쟁허브공항의 환승율인 30-40%와 비교해보면 공항경쟁력이 상당히 뒤쳐진다고 할 수 있다. 이러한 약점을 보완하기 위하여 여러 가지 관련 인자들을 검토하는 것이 중요하다고 판단되어지는데 그중에서 인천국제공항의 비행편최소연결시간(MCT)을 개선하는 것이 필요하다. 이러한 문제를 개선하기 위해서는 항공기 스케줄, 항공사 배치, 게이트 배정방법, 수하물처리, 여객 동선 등이 함께 검토되어야 할 것이다. 그러나 이러한 인자들에 대한 세부적인 분석이 단기간에 걸쳐 해결되는 문제가 아니기 때문에 본 연구에서는 외국 허브공항의 MCT 수준, 관리방법, 국외사례 등을 고찰해 보고 동북아시아에서 허브공항을 향한 인천국제공항의 환승율 제고차원에서 정책적 방안을 제시하고자 한다.

• Journal of the Korea Society of Computer and Information
• /
• v.16 no.11
• /
• pp.153-161
• /
• 2011

As the problem of GOSST building belongs to NP compete domain, heuristics for the problem ask for immense amount execution time and computations in large scale inputs. In this paper, we propose an efficient mechanism for GOSST construction using space locality PTAS. For 40,000 input nodes with maximum weight 100, the proposed space locality PTAS GOSST with 16 unit areas can reduce about 4.00% of connection cost and 89.26% of execution time less than weighted minimum spanning tree method. Though the proposed method increases 0.03% of connection cost more, but cuts down 96.39% of execution time less than approximate GOSST method (SGOSST) without PTAS. Therefore the proposed space locality PTAS GOSST mechanism can work moderately well to many useful applications where a greate number of weighted inputs should be connected in short time with approximate minimum connection cost.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.1C
• /
• pp.67-77
• /
• 2007

Virus throttling technique, one of many early worm detection techniques, detects Internet worm propagation by limiting connect requests within a certain ratio. The typical virus throttling controls the period of rate limiter autonomically by utilizing weighted average delay queue length to reduce connection delay time without hanving a large effect on worm detection time. In the existing virus throttling research, a minimum period of variable rate limiter is fired and a turning point which is a point that the period of rate limiter has been being decreased and starts to be increased is also fixed. However, these two performance factors have different effects on worm detection time and connection delay. In this paper, we analyze the effect of minimum period and turning point of variable rate limiter, and then propose an algorithm which determines values of performance factors by referencing current traffic pattern. Through deep experiments, it is verified that the proposed technique is more efficient in respect of reducing worm detection time and connection delay than the existing virus throttling which fixed the performance factors.

• Journal of the Korea Society of Computer and Information
• /
• v.19 no.6
• /
• pp.71-80
• /
• 2014

Employing PTAS to building minimum spanning tree for a large number of equal distribution input terminal nodes can be a effective way in execution time. But applying PTAS to building minimum spanning tree for tremendous unequal distribution node may lead to performance degradation. In this paper, a partial PTAS reflecting the scheme into specific node dense area is presented. In the environment where 90% of 50,000 input terminal nodes stand close together in specific area, approximate minimum spanning tree by our proposed scheme can show about 88.49% execution time less and 0.86%tree length less than by existing PTAS, and about 87.57%execution time less and 1.18% tree length more than by Prim's naive scheme. Therefore our scheme can go well to many useful applications where a multitude of nodes gathered around specific area should be connected efficiently as soon as possible.