• Journal of information and communication convergence engineering
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• v.8 no.1
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• pp.59-63
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• 2010

The shortest path between two points inside a simple polygon P is a minimum-length path among all paths connecting them which don't pass by the exterior of P. A linear time algorithm for computing the shortest path in a general simple polygon requires triangulating a given polygon as preprocessing. The linear time triangulating is known to very complex to understand and implement it. It is also inefficient in case that the input without very large size is given because its time complexity has a big constant factor. Two points of a polygon P are said to be L-visible from each other if they can be joined by a simple chain of at most two rectilinear line segments contained in P completely. An L-visible polygon P is a polygon such that there is a point from which every point of P is L-visible. We present the customized optimal shortest path algorithm for an L-visible polygon. Our algorithm doesn't require triangulating as preprocessing and consists of simple procedures such as construction of convex hulls and operations for convex polygons, so it is easy to implement and runs very fast in linear time.

• Communications for Statistical Applications and Methods
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• v.9 no.3
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• pp.845-851
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• 2002

An efficient method is developed to obtain the maximum flow for a network when its simple paths are known. Most of the existing techniques need to convert simple paths into minimal cuts, or to determine the order of simple paths to be applied in the process to reach the correct result. In this paper, we propose a method based on the concepts of signed simple path and signed flow defined in the text. Our method involves a fewer number of arithmetic operations at each iteration, and requires fewer iterations in the whole process than the existing methods. Our method can be easily extended to a mixed network with a slight modification. Furthermore, the correctness of our method does not depend on the order of simple paths to be applied in the process.

• Proceedings of the Korean Reliability Society Conference
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• 2002.06a
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• pp.297-302
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• 2002

An efficient method is developed to obtain the maximum capacity flow for a network when its simple paths are known. Most of the existing techniques need to convert simple paths into minimal cuts, or to determine the order of simple paths to be applied in the process to reach the correct result. In this paper, we propose a method based on the concepts of signed simple path and signed flow defined in the text. Our method involves a fewer number of arithmetic operations at each iteration, and requires fewer iterations in the whole process than the existing methods. Our method can be easily extended to a mixed network with a slight modification. Furthermore, the correctness of our method does not depend on the order of simple paths to be applied in the process.

• Journal of applied mathematics & informatics
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• v.7 no.1
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• pp.279-287
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• 2000

A simple estimate of Feynman path-integration with general potential via its new definition is given and found to be very useful. This new method will help find the value of some Feynman path-integrals as precise as one wants.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2423-2425
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• 2003

This paper proposes a decision criteria for selecting the shortest path from Dubins set between the initial and final configurations of a car-like robot. The suggested scheme is a very simple and computational savings without explicitly calculating the candidate paths and having a complicated decision table. Equations for calculating the shortest path are derived in simple form with coordinate transform and defining standard forms.

• Physical Therapy Korea
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• v.17 no.3
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• pp.20-30
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• 2010

This study examined whether any changes by mental task types on postural control in chronic stroke persons. Sixteen chronic stroke persons (mean age=53.75 yr) and sixteen age-and gender-matched healthy controls (mean age=54.44 yr) took part in this study. Participants randomly performed three different tasks on the stable and unstable surfaces. The no mental task was to stand while holding a 100 g weight in each hand, the arithmetic task (mental task) was to perform a silent 1-backwards counting while standing and holding a 100 g weight in each hand, and the simple task (mental task) was to stand and hold with both hands a tray (200 g) on which a glass filled with water has been placed. Sway path and sway velocity of the center of pressure (COP) were measured to assess standing postural control by task performance using the force platform. According to the results, in stroke group, total sway path and total sway velocity of COP was significantly decreased during arithmetic and simple task compared to no mental task on the stable surface (p<.05), and sway path (anteroposterior AP, mediolateral ML) of COP, total and sway velocity (AP, ML, total) of COP was significantly decreased during arithmetic and simple task compared to no mental task on the unstable surface (p<.05). Especially, sway path (AP, total) of COP and sway velocity (AP, ML, total) of COP was significantly decreased under the simple task when compared to the arithmetic task on the unstable surface (p<.05). In healthy control group, sway path (AP, ML, total) of COP and sway velocity (AP, ML, total) of COP was significantly decreased during arithmetic and simple task compared to no mental task on the stable and unstable surface (p<.05), and sway path (AP, total) of COP and sway velocity (AP, ML, total) of COP was significantly decreased under the simple task when compared to the arithmetic task on the unstable surface (p<.05). In conclusion, the findings of this study showed that arithmetic and simple task improved standing postural control for chronic stroke patients and the type of arithmetic and simple tasks were critical factor that reduced standing postural sway in dual-task conditions. Future research should determine whether dual-task conditions, including simple task, would be effective as a training program for standing postural control of stroke patients.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.2
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• pp.369-374
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• 2010

The shortest path between two points inside a simple polygon P is a minimum-length path among all paths connecting them which don't pass by the exterior of P. A linear time algorithm for computing the shortest path in a general simple polygon requires triangulating a polygon as preprocessing. The linear time triangulating is known to very complex to understand and implement it. It is also inefficient in case that the input without very large size is given because its time complexity has a big constant factor. In this paper, we present the customized shortest path algorithm for a segment-visible polygon which is a simple polygon weakly visible from an internal line segment. Our algorithm doesn't require triangulating as preprocessing and consists of simple procedures such as construction of convex hulls, so it is easy to implement and runs very fast in linear time.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.807-810
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• 2009

In this paper, we consider the shortest path problems in a simple polygon. The shortest path between two points inside a polygon P is a minimum-length path among all paths connecting them which don't pass by the exterior of P. A linear time algorithm for computing the shortest path in a general simple polygon requires triangulating a polygon as preprocessing. The linear time triangulating is known to very complex to understand and implement it. It is also inefficient in cases without very large input size. In this paper, we present the customized shortest path algorithms for specific polygon classes such as star-shaped polygons, edge-visible polygons, and monotone polygons. These algorithms need not triangulating as preprocessing, so they are simple and run very fast in linear time.

• Journal of the Korea Society for Simulation
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• v.12 no.1
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• pp.11-19
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• 2003

Dubins showed that any shortest path of a car-like robot consists of exactly three path segment which are either arcs of circles of radius r(denoted C), or straight line segments(denoted S). Possible six types classified into two families, i.e. CSC and CCC. CSC includes 2 types(LRL and RLR) and CSC includes 4 types(LSL, RSR, LSR, RSL). This paper proposes new formulae for CSC family to find the shortest smooth path between the initial and final configurations of a car-like robot. The formulae is used for finding connection points explicitly between C\longrightarrowS and S\longrightarrowC which are necessary for real applications. The formulae have simple forms mainly because they are transformed into origin of their original coordinates of initial and target configuration, and derived from a standard forms which are a representative configuration of LSL and LSR type respectively. The proposed formulae, which are derived from the standard forms, are simple and new method.

• Journal of the Korean Statistical Society
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• v.21 no.2
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• pp.201-207
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• 1992

The algorithm for obtaining the isotonic regression in simple tree order, the most basic and simplest model next to the simple order, is considered. We propose to call it "Pool-the-Maximum-Violators" algorithm (PMVA) in conjunction with the "Pool-Adjacent-Violators" algorithm (PAVA) in the simple order. The dual problem of obtaining the isotonic regression in simple tree order is our main concern. An intuitively appealing relation between the primal and the dual problems is demonstrated. The interesting difference is that in simple order the required number of pooling is at least the number of initial violating pairs and any path leads to the solution, whereas in the simple tree order it is at most the number of initial violators and there is only one advisable path although there may be some others leading to the same solution.o the same solution.