• 대한기계학회논문집A
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• 제25권12호
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• pp.2009-2018
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• 2001

This paper presents a region offsetting algorithm for tool-path generation. The proposed region offsetting algorithm is developed by expanding the 'PWID offset algorithm [Choi and Park, 1999]'designed to offset a simple polygon. The PWID offset algorithm has three important steps; 1) remove 'local invalid ranges'by invoking a PWID test, 2) construct a raw offset owe and 3) remove 'global invalid ranges'by finding self-intersections of the raw offset cure. To develop a region offsetting algorithm, we modified the PWID offset algorithm by expanding the concept of the 'global invalid range'in the third step. The time complexity of the proposed algorithm is approximately Ο(n), where n is the number of points, and it is free of numerical errors for practical purposes. The proposed algorithm has been implemented and tested with various real regions obtained by intersecting a sculptured surface with a plane.

• 대한수학회지
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• 제34권1호
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• pp.181-193
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• 1997

The enumeration of various classes of paths in the real plane has an important implications in the area of combinatorics wit statistical applications. In 1887, D. Andre [3, pp. 21] first solved the famous ballot problem, formulated by Berttand [2], by using the well-known reflection principle which contributed tremendously to resolve the problems of enumeration of various classes of lattice paths in the plane. First, it is necessary to state the definition of NSEW-paths in the palne which will be employed throughout the paper. From [3, 10, 11], we can find results concerning many of the basics discussed in section 1 and 2.

• ETRI Journal
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• 제38권6호
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• pp.1031-1041
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• 2016

This paper presents millimeter-wave (mmWave) propagation characteristics and channel model parameters including path loss, delay, and angular properties based on 28 GHz and 38 GHz field measurement data. We conducted measurement campaigns in both outdoor and indoor at the best potential hotspots. In particular, the model parameters are compared to sub-6 GHz parameters, and system design issues are considered for mmWave 5G Giga communications. For path loss modeling, we derived parameters for both the close-in free space model and the alpha-beta-gamma model. For multipath models, we extracted delay and angular dispersion characteristics including clustering results.

• 한국정보과학회논문지:시스템및이론
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• 제34권10호
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• pp.539-554
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• 2007

이 논문에서는 진구간 그래프(proper interval graph)가 각각 일대일, 일대다. 다대다 k-서로소인 경로 커버를 가질 조건을 고찰한다. 진구간 그래프는 $k{\geq}2$인 경우, k-연결되어 있는 경우에만 일대일 k-서로소인 경로 커버를 가지며, k+1-연결되어 있는 경우에만 일대다 k-서로소인 경로 커버를 가짐을 증명하였다. 그리고 $k{\geq}3$일 때 진구간 그래프는 2k-1-연결되어 있는 경우에만 (쌍형) 다대다 k-서로소인 경로 커버를 가진다.

• 한국정밀공학회지
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• 제26권2호
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• pp.63-70
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• 2009

This paper proposes a novel path finding approach of a mobile robot using RF strength in sensor network. In the experiments based on the proposed method, a mobile robot attempts to find its location, heading direction and the shortest path in the indoor environment. The experimental system consisting of mesh network shares node data and send them to base station. The triangulation and the proposed Grid method calculate the location and heading angle of the robot. In addition, the robot finds the shortest path by using the base station attached on it to receive data of environment around each node. Kalman filter reduces the straight line error when the robot estimates the strength of received signal. The experimental results show the effectiveness of the proposed algorithm.

• 제어로봇시스템학회논문지
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• 제16권9호
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• pp.891-897
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• 2010

This paper proposes a cooperative control algorithm for a dual-arms robot which is carrying an object to the desired location. When the dual-arms robot is carrying an object from the start to the goal point, the optimal path in terms of safety, energy, and time needs to be selected among the numerous possible paths. In order to quantify the carrying efficiency of dual-arms, DAMM (Dual Arm Manipulability Measure) has been defined and applied for the decision of the optimal path. The DAMM is defined as the intersection of the manipulability ellipsoids of the dual-arms, while the manipulability measure indicates a relationship between the joint velocity and the Cartesian velocity for each arm. The cost function for achieving the optimal path is defined as the summation of the distance to the goal and inverse of this DAMM, which aims to generate the efficient motion to the goal. It is confirmed that the optimal path planning keeps higher manipulability through the short distance path by using computer simulation. To show the effectiveness of this cooperative control algorithm experimentally, a 5-DOF dual-arm robot with distributed controllers for synchronization control has been developed and used for the experiments.

• 한국정밀공학회지
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• 제16권12호
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• pp.204-213
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• 1999

This paper suggests a numerical method of finding optimal geometric path and minimum-time motion for a manipulator arm. To find the minimum-time motion, the optimal geometric path is searched first, and the minimum-time motion is searched on this optimal path. In the algorithm finding optimal geometric path, the objective function is minimizing the combination of joint velocities, joint-jerks, and actuator forces as well as avoiding several static obstacles, where global search is performed by adjusting the seed points of the obstacle models. In the minimum-time algorithm, the traveling time is expressed by the linear combinations of finite-term quintic B-splines and the coefficients of the splines are obtained by nonlinear programming to minimize the total traveling time subject to the constraints of the velocity-dependent actuator forces. These two search algorithms are basically similar and their convergences are quite stable.

• 한국경영과학회지
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• 제16권2호
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• pp.86-102
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• 1991

The purpose of this paper is to present a branch and bound algorithm for the hierarchical transportation network design problem in 2-level directed networks. This problem is to find the least cost of hierarchical transportation networks which consist of a primary path and a secondary path. The primary path is a simple path from a prespecified orgin node to a prespecified terminal node. All nodes must be either a transsipment node on the primary path or connected to that path via secondary arcs. This problem is formulated to a 0-1 inter programming problem with assignment and illegal subtour elimination equations as constaints. We show that the subproblem relaxing subtour elimination constraints is transformed to a linear programming problem by means of the totally unimodularity. Optimal solutions of this subproblem are polynoially obtained by the assignment algorithm and complementary slackness conditions. Therefore, the optimal value of this subproblme is used as a lower bound. When an optimal solution of the subproblem has an illegal subtour, a better disjoint rule is adopted as the branching strategy for reducing the number of branched problems. The computational comparison between the least bound rule and the depth first rule for the search strategy is given.

• 정보처리학회논문지D
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• 제11D권7호
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• pp.1409-1416
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• 2004

최근 인터넷의 폭발적인 성장과 인기로 인하여 인터넷을 통한 정보 교환이 극적으로 증가하고 있다. 또한 XML은 인터넷상에서 데이터를 교환하기 위한 표준인 동시에 중요한 수단이 되고 있다. 따라서 XML 문서를 검색하는데 있어서, 경로-지향 질의에 대한 평가 속도를 개선하는 문제는 중요한 이슈이다. 본 논문에서는 문서 데이터베이스에서 경로-지향 질의의 검색 성능을 개선하기 위한 새로운 인덱싱 방법을 제안하다. 새로운 인덱싱 방법에서는 경로-지향 질의를 효과적으로 수행하기 위해 단축-경로 파일을 생성하고 그것의 해시 코드 값을 인덱스 키로 사용한다. 또한 검색 평가 속도를 촉진시키기 위하여 단축-경로 파일을 확장성 해싱 기법과 결합하는 것으로 검색질의의 평가속도를 가속화하였다.

• Journal of the Optical Society of Korea
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• 제15권4호
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• pp.380-385
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• 2011

Common-path interferometers are widely used for endoscopic optical coherence tomography (OCT) because an arbitrary arm length can be chosen for the endoscopic imaging probe. However, the scheme suffers from the limited range of the sample position distance from the end of the imaging probe because the position between the reference reflector and the sample is limited by the optical path-length difference (OPD) to induce an interference signal. In this study, we developed a novel method for compensating the arbitrary sample position in common-path swept-source OCT by adding an extra Mach-Zehnder interferometer in the post-path of the interfered optical signal. Theoretical analysis and an experimental demonstration of imaging depth tuning for the flexible sample position of an endoscopic OCT image are discussed. After post-tuning of sample position distance, the positioning limitation between the reference reflector and the sample can be solved for various sample positions over a range of 26 mm for the cross-sectional images of a fish eye sample.