• Journal of Institute of Control, Robotics and Systems
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• v.17 no.5
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• pp.471-478
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• 2011

This UGV (Unmanned Ground Vehicle) is not only widely used in various practical applications but is also currently being researched in many disciplines. In particular, obstacle avoidance is considered one of the most important technologies in the navigation of an unmanned vehicle. In this paper, we introduce a simple algorithm for path planning in order to reach a destination while avoiding a polygonal-shaped static obstacle. To effectively avoid such an obstacle, a path planned near the obstacle is much shorter than a path planned far from the obstacle, on the condition that both paths guarantee that the robot will not collide with the obstacle. So, to generate a path near the obstacle, we have developed an algorithm that combines an edge detection method and a limit-cycle navigation method. The edge detection method, based on Hough Transform and IR sensors, finds an obstacle's edge, and the limit-cycle navigation method generates a path that is smooth enough to reach a detected obstacle's edge. And we proposed novel algorithm to solve local minima using the virtual wall in the local vision. Finally, we verify performances of the proposed algorithm through simulations and experiments.

• Journal of applied mathematics & informatics
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• v.39 no.1_2
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• pp.223-237
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• 2021

Let G = (V (G), E(G)) be a graph and let g : V (G) → S3 be a function. For each edge xy assign the label r where r is the remainder when o(g(x)) is divided by o(g(y)) or o(g(y)) is divided by o(g(x)) according as o(g(x)) ≥ o(g(y)) or o(g(y)) ≥ o(g(x)). The function g is called a group S3 cordial remainder labeling of G if |vg(i)-vg(j)| ≤ 1 and |eg(1)-eg(0)| ≤ 1, where vg(j) denotes the number of vertices labeled with j and eg(i) denotes the number of edges labeled with i (i = 0, 1). A graph G which admits a group S3 cordial remainder labeling is called a group S3 cordial remainder graph. In this paper, we prove that square of the path, duplication of a vertex by a new edge in path and cycle graphs, duplication of an edge by a new vertex in path and cycle graphs and total graph of cycle and path graphs admit a group S3 cordial remainder labeling.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.59
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• pp.1-10
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• 2000

The traveling salesman problem is a representative NP-Complete problem. It needs lots of time to get a solution as the number of city increase. So, we need an efficient heuristic algorithm that gets good solution in a short time. Almost edges that participate in optimal path have somewhat low value cost. This paper discusses the property of nearest neighbor and 3-opt. This paper uses nearest neighbor's property to select candidate edge. Candidate edge is a set of edge that has high probability to improve cycle path. We insert edge that is one of candidate edge into intial cycle path. As two cities are connected. It does not satisfy hamiltonian cycle's rule that every city must be visited and departed only one time. This paper uses 3-opt's method to sustain hamiltonian cycle while inserting edge into cycle path. This paper presents a highly efficient heuristic algorithm verified by numerous experiments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8A
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• pp.581-590
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• 2003

This paper proposes the routing path selection mechanism for source routing-based PtMP (Point-to-Multipoint) call in ATM switching system. Especially, it suggests PtMP routing path selection method that can share the maximum resource prior to the optimal path selection, guarantee the reduction of path calculation time and cycle prevention. The searching for the nearest branch point from destination node to make the maximum share of resource is the purpose of this algorithm. Therefore among neighbor nodes from destination node by back-tracking, this algorithm fixes the node crossing first the node on existing path having the same Call ID as branch node, constructs the optimal PtMP routing path. The optimal node to be selected by back-tracking is selected by the use of Dijkstra algorithm. That is to say, PtMP routing path selection performs the step of cross node selection among neighboring nodes by back-tracking and the step of optimal node selection(optimal path calculation) among neighboring nodes by back-tracking. This technique reduces the process of search of routing information table for path selection and path calculation, also solves the cycle prevention easily during path establishment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1050-1053
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• 1995

A stock removal cycle is developed as a programming tool of the CNC lathe. This cycle support the easiness and swifness of a part program generation in the shopfloor. The cycle contains the function of tool path generation of rough/finish cutting, of avoidance air-cut for non-cylindrical (die-casted, forged) workpiece, and of the tool collisopn detection/aviodance. Consequently the intelligent stock removal cycle results in improving the productivity and safety of CNC lathe.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2311-2318
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• 2005

Progress in the LCD industries has been very rapid. Therefore, their manufacturing lines require larger LCD glass-handling robots and more precise path control of the robots. In this paper, we present two practical advanced algorithms for high-precision path generation of an LCD glass-handling robot. One is high-precision path interpolation for continuous motion, which connects several single motions and is a reliable solution for a short robot cycle time. We demonstrate that the proposed algorithm can reduce path error by approximately 91% compared with existing algorithms without increasing cycle time. The second is real-time static deflection compensation, which can optimally compensate the static deflection of the handling robot without any additional sensors, measurement instruments or mechanical axes. This reduces vertical path error to approximately 60% of the existing system error. All of these algorithms have been commercialized and applied to a seventh-generation LCD glass-handling robot.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.4
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• pp.365-370
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• 2012

Most path planning algorithms for a marine robot in the ocean environment have been developed without considering the robot's heading angle. As a result, the robot has a difficulty in following the path correctly. In this paper, we propose a limit-cycle circle set that applies to the $Theta^*$ algorithm. The minimum turning radius of a marine robot is calculated using a limit-cycle circle set, and circles of this radius is used to generate a configuration space of an occupancy grid map. After applying $Theta^*$ to this configuration space, the limit-cycle circle set is also applied to the start and end nodes to find the appropriate path with specified heading angles. The benefit of this algorithm is its fast computation time compared to other 3-D ($x,y,{\theta}$) path planning algorithms, along with the fact that it can be applied to the 3-D kinematic state of the robot. We simulate the proposed algorithm and compare it with 3-D $A^*$ and 3-D $A^*$ with post smoothing algorithms.

• Journal of KIISE:Information Networking
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• v.30 no.5
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• pp.668-675
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• 2003

In this paper, we propose an enhanced p-cycle (preconfigured protection cycle) scheme for WDM mesh networks with QoS constraints. In the previous researches on p-cycle, it is assumed that user's connection has a hi-directional connectivity and the same bandwidth on both direction. Therefore it is difficult to apply p-cycle based link protection to uni-directional connections for multicasting or asymmetric broadband multimedia communications with hi-directional connectivity. And it didn't consider QoS of backup path. We enhanced the p-cycles to accomodate uni-directional connections for multicasting or asymmetric bandwidth communications with hi-directional connectivity. And we propose a selection procedure of p-cycle to assure QoS of backup path. We were able to reduce a required backup bandwidth by applying a uni-directional p-cycle concept to asymmetric broadband multimedia communication environment. The proposed p-cycle selection procedure is applied to the U.S. sample network to evaluate whether the configured p-cycles can support QoS constraint of working path and backup path.

• Journal of the Korea Society of Computer and Information
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• v.21 no.7
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• pp.47-52
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• 2016

This paper introduces an algorithm to construct an Eulerian cycle for Chinese postman problem. The Eulerian cycle is formed only when all vertices in the graph have an even degree. Among available algorithms to the Eulerian cycle problem, Edmonds-Johnson's stands out as the most efficient of its kind. This algorithm constructs a complete graph composed of shortest path between odd-degree vertices and derives the Eulerian cycle through minimum-weight complete matching method, thus running in $O({\mid}V{\mid}^3)$. On the contrary, the algorithm proposed in this paper selects minimum weight edge from edges incidental to each vertex and derives the minimum spanning tree (MST) so as to finally obtain the shortest-path edge of odd-degree vertices. The algorithm not only runs in simple linear time complexity $O({\mid}V{\mid}log{\mid}V{\mid})$ but also obtains the optimal Eulerian cycle, as the implementation results on 4 different graphs concur.

• The KIPS Transactions:PartC
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• v.9C no.5
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• pp.655-664
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• 2002

The focus of quality-of-service routing has been on the routing of a single path satisfying specified QoS constraints. However upon failure of a node or link on the path, a new path (backup path) satisfying the constraints has to be established. This paper proposed the fault recovery QoS Rerouting algorithms to recovery the service of applications under fault environment of network. For this, we describes the generation method of PFC (Protection Fundamental Cycle) protecting all of network nodes and suggests path selection algorithms using minimization rerouting cost problem and analyzes the performances of these.