• Journal of Korean Institute of Industrial Engineers
• /
• v.27 no.2
• /
• pp.140-149
• /
• 2001

The paper discusses the problem of finding the Origin-Destination(O-D) shortest paths in internodal transportation networks with time-schedule constraints. The shortest path problem on the internodal transportation network is concerned with finding a path with minimum distance, time, or cost from an origin to a destination using all possible transportation modalities. The time-schedule constraint requires that the departure time to travel from a transfer station to another node takes place only at one of pre-specified departure times. The scheduled departure times at the transfer station are the times when the passengers are allowed to leave the station to another node using the relative transportation modality. Therefore, the total time of a path in an internodal transportation network subject to time-schedule constraints includes traveling time and transfer waiting time. In this paper, a genetic algorithm (GA) approach is developed to deal with this problem. The effectiveness of the GA approach is evaluated using several test problems.

• Journal of the military operations research society of Korea
• /
• v.18 no.2
• /
• pp.151-166
• /
• 1992

In this paper, we define a problem finding a simple path that maximizes the sum of the satisfied Origin-Destination (O-D) flows between nodes covered by that path as a Maximum O-D Flow Path Problem(MODEP). We established a formulation and suggested a method finding MODEP in a directed network. The method utilizes the constraint relaxation technique and the Dual All Integer Algorithm.

• Journal of the Korea Society for Simulation
• /
• v.14 no.3
• /
• pp.21-31
• /
• 2005

In state-of-the-art games, characters can move in a goal-directed manner so that they can move to the goal position without colliding obstacles. Many path-finding methods have been proposed and implemented for these characters and most of them use the A* search algorithm. When .the map is represented with a regular grid of squares or a navigation mesh, it often takes a long time for the A* to search the state space because the number of cells used In the grid or the mesh increases for higher resolution. Moreover the A* search on the grid often causes a zigzag effect, which is not optimal and realistic. In this paper we propose to use visibility graphs to improve the search time by reducing the search space and to find the optimal path. We also propose a method of taking into account the size of moving characters in the phase of planning to prevent them from colliding with obstacles as they move. Simulation results show that the proposed method performs better than the grid-based A* algorithm in terms of the search time and space and that the resulting paths are more realistic.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2010.04a
• /
• pp.27-28
• /
• 2010

Finding shortest path technique running time differs depending on applying of the algorithm and data, and also used a lot of difference in effectiveness depending on the environment occurs. Therefore, the algorithm and environment based on this study, the relationship between optimal solutions and compare running time.

• Proceedings of the KIEE Conference
• /
• 2004.11c
• /
• pp.447-449
• /
• 2004

We proposed the method of the production of the humanoid biped robot and apply the A* path finding algorithm, for that robot mainly used in game and mobile robot, to avoid obstacles at real time. Actually we made the robot which has 20 DOF, 12 DOF in the two legs, 6 DOF in the two arms and each 1 DOF in the neck and waist, to realize human motions with minimal DOF, And we use the CATIA V5 for 3D modeling design and simulate.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.3D
• /
• pp.317-323
• /
• 2008

Mass transit information can contribute many benefits to users. Especially, transportation information technology is developing highly with information technology in Korea recently. Hereafter, it is expected to give customized transportation information to users individually with the advent of ubiquitous age in earnest. This public transportation information service can be realized by path finding algorithm in public transportation networks including travel and transfer attributes. In this research, constraints are constructed with the primary facts influencing users. Moreover, the method reducing user's path finding condition arbitrarily is proposed by making the maximum value as variables. In this study, transfer frequency, total travel time, seat confirmation, transfer time and travel time become constraint condition based on k path finding algorithm considering service time constraint condition. Moreover, case study about user customized transfer information is performed in Seoul and metropolitan subway networks.

• Journal of the military operations research society of Korea
• /
• v.17 no.2
• /
• pp.72-89
• /
• 1991

In transportation network problems, it is often desirable to select multiple number of the shortect paths. On problems of finding these paths, algorithms have been developed to choose single shortest path, k-shortest paths and k-shortest paths via p-specified nodes in a network. These problems consider the time as the main factor. In wartime, we must consider availability as well as time to determine the shortest transportation path, since we must take into account enemy's threat. Therefore, this paper addresses the problem of finding the shortest transportation path considering both time and availability. To accomplish the objective of this study, values of k-shortest paths are computed using the algorithm for finding the k-shortest paths. Then availabilties of those paths are computed through simulation considering factors such as rates of suffering attack, damage and repair rates of the paths. An optimal path is selected using any one of the four decision rules that combine the value and availability of a path.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2007.06a
• /
• pp.323-326
• /
• 2007

When traveling on real road network, it generally takes less travel time in a near straight path than a zig-zaged path with same source and destination. In order to making a left(right/u) turn, the delay should be required to decrease the speed. The traffic signal waiting time of left(right/u) turn is probably longer than straight driving. In this paper, we revise the previous hierarchical path finding algorithm to reduce the number of turns. The algorithm proposed in this paper complied with a hierarchical $A^*$ algorithm, but has a distinct strategy for edge weight. We define an edge that makes a turn as a turn-edge and give the turn-edge lower weight to maintain the straightness of the whole path.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.10a
• /
• pp.65-69
• /
• 2001

Network Management become more and more important issue in the network environment in which many applications such as Mail, teleconferencing, WWW and database software are operated. It can be possible for The Bridge and flouter forwarding data to select next hop device which results in routing incorrect path from the viewpoint of network design. In this paper we address the problem of finding the detour routing path due to incorrect setting on routing devices. We propose the new algorithm for finding detour routing path based on hierarchical network structure analysis using information from SNMP MIB. To prove the correctness of the proposed algorithm we have done simulation with predefined data. Simulation results show that the algorithm finds detour path correctly

• Journal of the military operations research society of Korea
• /
• v.26 no.2
• /
• pp.1-7
• /
• 2000

A quickest path in a network is a path that takes the shortest time to send the amount of data from the source node to the sink node. Martin and Santos presented a theorem on the quickest path by which a quickest path for the amount of data is determined. However, we find a counterexample to Martins and Santos' theorem. In this paper, we present the corrected theorem and give a revised algorithm for finding quickest paths.