• Proceedings of the Korean Information Science Society Conference
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• 1999.10b
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• pp.440-442
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• 1999

본 논문에서는 가중치 3차원 공간을 가중치 8진트리를 이용하여 나타낸다. 가중치 8진트리는 가중치 영역을 계층적으로 나타내고 용이하게 분해능을 조절할 수 있게 한다. 즉 높은 가중치를 갖는 공간은 세밀하게 분해하고 낮은 가중치를 갖는 공간은 성길하게 분해하여 최적의 경로설정을 바른 시간에 할 수 있도록 한다. 이러한 8진트리를 바탕으로 하여 최적 경로 설정하는 종합틀(Framework)을 제시하고 실험을 통하여 그 결과를 제시한다.

• Journal of Korean Society of Transportation
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• v.23 no.7 s.85
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• pp.99-110
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• 2005

Total travel cost of route which connects origin with destination (O-D) is consist of the total sum of link travel cost and route perception cost. If the link perception cost is different according to the origin and destination, optimal route search has limitation to reflect the actual condition by route enumeration problem. The purpose of this study is to propose optimal route searching formulation and algorithm which is enable to reflect different link perception cost by each route, not only avoid the enumeration problem between origin and destination. This method defines minimum unit of route as a link and finally compares routes using link unit costs. The proposed method considers the perception travel cost at both origin and destination in optimal route searching process, while conventional models refect the perception cost only at origin. However this two-way searching algorithm is still not able to guarantee optimum solution. To overcome this problem, this study proposed an orign based optimal route searching method which was developed based on destination based optimal perception route tree. This study investigates whether proposed numerical formulas and algorithms are able to reflect route perception behavior reflected the feature of origin and destination in a real traffic network by the example research including the diversity of route information for the surrounding area and the perception cost for the road hierarchy.

• Journal of KIISE:Information Networking
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• v.29 no.1
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• pp.48-56
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• 2002

This paper proposes an IP(Internet Protocol) multicast routing method by multiple tree routes. Multiple trees, instead of a single tree, improve the quality of multicast services with nonlinear link cost and huge traffic demand. The proposed method adds tree routes until it satisfies target conditions, and it splits the multicast traffic demand into the chosen tree routes. We develop a mathematical model and optimal conditions for traffic splitting. The method works on the problems with many different simultaneous multicast traffic. Various experiments were carried and the results show that the new multicasting is fairly effective on end-to-end quality of services.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.17-17
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• 2004

자율 이동로봇은 현재 각광을 받고 있는 서비스로봇의 연구와 더불어 활발히 연구되고 있다. 그 중 경로계획 부분에 대한 연구는 Roadmap Method, Cell Decomposition, Potential Field Method로 크게 구분하여 연구되고 있다. 그러나 경로계획 기법에 있어서 기존의 정형화된 방법 이외에 다른 방법들이 제시 되지 않고 있다. 기존 경로계측의 문제점들은 다음과 같다. 국부최소(local minimum)를 회피하지 못하거나, 많은 계산량으로 인해 넓은 범위에 적용시킬 수 없다는 문제점, 오프라인으로 경로의 최적성에만 치중하여 실시간으로 적용하기가 쉽지 않으며, 돌발적인 상황에 대처하기 어렵다는 문제점 등을 가지고 있다.(중략)

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.5_6
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• pp.195-201
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• 2007

A minimum terminal path decomposition of a tree is defined as a partition of the tree into edge-disjoint terminal-to-terminal paths that minimizes the weight of the longest path. In this paper, we present an $O({\mid}V{\mid}^2$time algorithm to find a minimum terminal path decomposition of trees. The algorithm reduces the given optimization problem to the binary search using the corresponding decision problem, the problem to decide whether the cost of a minimum terminal path decomposition is at most l. This decision problem is solved by dynamic programing in a single traversal of the tree.

• 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.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11b
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• pp.883-886
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• 2003

호스트의 위치를 동적으로 관리해야 하는 이동 통신망 환경에서 멀티캐스트 서비스 지원을 위하여 기존 고정 통신망 환경에서 사용되는 멀티캐스트 프로토콜의 사용은 부적합하다. 이동 호스트의 이동성을 보장하기 위하여 IETF에서는 원격 가입(remote subscription)과 양방향 터널링(bidirectional tunneling)을 제안하였다. 하지만, 이 방법들 또한 경로 비최적화 문제, 멀티캐스트 트리의 빈번한 재구성 등의 문제점을 가지고 있다. 본 논문에서는 Mobile IPv4 지역 등록 기법을 이용함으로써 이동 호스트의 이동 후 등록 절차에서 나타나는 지연을 줄였다. 그리고, 멀티캐스트 트리의 빈번한 재구성을 줄이기 위해서 로컬 네트워크의 GFA(gateway foreign agent)가 실제 트리에 가입한다. 그러므로 로컬 네트워크 내의 움직임은 트리 재구성에 영향을 미치지 않도록 하였다. 또한 이동 호스트는 이전 DFA에게 멀티캐스트 데이터를 포워딩 받을 수도 있고, 현재의 GFA가 직접 멀티캐스트 트리에 가입하여 데이터를 받을 수 있다. 이러한 기법들을 사용하여 경로 비최적화 문제를 해결하고, 트리 재구성 빈도를 줄일 수 있는 방안을 제시하였다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.4 no.3 s.8
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• pp.9-22
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• 2005

Route travel cost in transportation networks consists of actual route travel cost and route perception cost. Since the route perception cost is differently perceived according to each origin and each destination, route search has limitation to reflect the note perception cost due to route enumeration problem. Thus, currently employed advanced traveller information systems (ATIS) have considered only actual route travel cost for providing route information. This study proposes an optimal and a K-route searching algorithm which are able to reflect the route perception cost but encompass route enumeration problem. For this purpose, this research defines the minimum nit of route as a link by adopting the link label technique in route searching, therefore the comparison of two adjacent links which can be finally expanded the comparison of two routes. In order to reflect the characteristics of route perception in real situation, an optimal shortest cost path algorithm that both the forward search from the origin and the backward search from the destination can be simultaneously processed is proposed. The proposed algorithm is applied for finding K number of shortest routes with an entire-path-deletion-type of K shortest route algorithm.

• Korean Journal of Construction Engineering and Management
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• v.11 no.4
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• pp.68-79
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• 2010

During the last two decades, several tele-operated and machine-vision-assisted systems have been developed in construction and maintenance area such as pavement crack sealing, sewer pipe rehabilitation, and excavation. In developing such tele-operated and machine-vision-assisted systems, trajectory plans are very important tasks for optimal motions of robots whether their environments are structured or unstructured. This paper presents an optimal trajectory planning algorithm used for a machine-vision-assisted automatic pavement crack sealing system. In this paper, the performance of the proposed optimal trajectory planning algorithm is compared with the greedy trajectory plans which are used in previously developed pavement crack sealing systems. The comparison is based on computational cost versus overall gains in crack sealing efficiency. Finally, it is concluded that the proposed algorithm plays an important role in productivity improvement of the automatic pavement crack sealing system developed.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.5
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• pp.429-436
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• 2009

Odd network was introduced as one model of graph theory. In [1], it was introduced as a class of fault-tolerant multiprocessor networks and analyzed so many useful properties such as simple routing algorithms, maximal fault tolerance, node axsjoint path, etc. In this paper, we sauw a construction algorithm of edge-axsjoint spanning trees in Odd network $O_d$. Also, we prove that edge-disjoint spanning tree generated by our algorithm is optimal edge-disjoint spanning tree.