• International Journal of CAD/CAM
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• v.2 no.1
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• pp.23-28
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• 2002

This paper presents an efficient line-offset algorithm for general polygonal shapes with islands. A developed sweep-line algorithm (SL) is introduced to find all self-intersection points accurately and quickly. The previous work is limited to handle polygons that having no line-segments in parallel to sweep-line directions. The proposed algorithm has been implemented in Visual C++ and applied to offset point sequence curves, which contain several islands.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.1
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• pp.63-70
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• 2009

Proposed in the paper is an algorithm to generate tool-path for sculptured surface machining. The proposed algorithm computes tool path by slicing offset triangular mesh, which is the CL-surface (Cutter Location surface). Since the offset triangular mesh includes invalid triangles and self-intersections, it is necessary to remove invalid portions. For the efficient removal of the invalid portions, we extended the sweep line algorithm. The extended sweep line algorithm removes invalid portions very efficiently, and it also considers various degeneracy cases including multiple intersections and overlaps. The proposed algorithm has been implemented and tested with various examples.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.1
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• pp.133-140
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• 2014

An efficient heuristic for two-vehicle-one-depot problems is developed in this research. Vehicle moving speeds are various along hour based time intervals due to traffic jams of rush hours. Two different heuristics are examined. One is that the delivery area assignment is made using Sweep algorithm for two vehicles by splitting the whole area in half to equally divide all delivery points. The other is using common area by leaving unassigned area between the assigned for two vehicles. The common area is reassigned by two stages to balance the completion time of two vehicle's delivery. The heuristic with common area performed better than the other due to various vehicle moving speeds and traffic jams.

• Journal of the Korea Computer Graphics Society
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• v.21 no.1
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• pp.13-21
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• 2015

We present a robust GPU algorithm constructing a sweep volume boundary for a triangular mesh model. Sweeping geometric entities of a triangular mesh object is first approximated to a set of triangles, the envelope of which becomes the outer boundary of the sweep volume. We find the envelope by computing the arrangement of the triangle set and extracting its outmost boundary. To ensure robustness of the algorithm, we adopt random perturbation of sweep vertices and the interval arithmetic using multi-level precisions. The algorithm is implemented to perform most computation on GPU, and as a result it runs two orders of magnitude faster than other algorithms.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.7
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• pp.620-628
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• 2016

The homotopy algorithm provides a robust method for determining optimal control, in some cases the global minimum solution, as a continuation parameter is varied gradually to regulate the contributions of the nonlinear terms. In this paper, the Successive Backward Sweep (SBS) method, which is insensitive to initial guess, augmented with a homotopy algorithm is suggested. This approach is effective for highly nonlinear problems such as low-thrust trajectory optimization. Often, these highly nonlinear problems have multiple local minima. In this case, the SBS-homotopy method enables one to steadily seek a global minimum.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1617-1622
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• 1991

Plane sweep is a general method in computational geometry. There are many efficient theoretical algorithms designed using plane sweep technique. However, their practical implementations are still suffering from the topological inconsistencies resulting from the numerical errors in geometric computations with finite-precision arithmetic. In this paper, we suggest new implementation techniques for the plane sweep algorithms to resolve the topological inconsistencies and construct the planar object boundaries from given input curve segments.

• Korean Journal of Computational Design and Engineering
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• v.4 no.2
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• pp.162-171
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• 1999

Plane sweep plays an important role in computational geometry. This paper shows that an extension of topological plane sweep to three-dimensional space can calculate the volume swept by rotating a solid polyhedral object about a fixed axis. Analyzing the characteristics of rotational swept volumes, we present an incremental algorithm based on the three-dimensional topological sweep technique. Our solution shows the time bound of O(n²·2?+T?), where n is the number of vertices in the original object and T? is time for handling face cycles. Here, α(n) is the inverse of Ackermann's function.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.691-693
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• 2002

일반화 다각형(generalized polygons)이란 선분과 호로 둘러싸인 $R^2$영역으로 정의되는 확장된 다각형 개념으로 로보틱스 등의 응용 분야에서 다루는 중요한 도형군이다. 로보틱스에 응용되는 컴퓨터 기하학 알고리즘의 대부분은 선분이나 다각형을 다루도록 개발되어 있어 로봇 작업환경의 다양한 물체들을 선분만으로 모델링해야만 알고리즘의 적용이 가능하다. 기존의 알고리즘들을 일반화 다각형을 다룰 수 있도록 확대한다면 보다 유연한 모델링을 가능하게 할 것이다. 주 논문에서는 컴퓨터 기하학분야의 대표적인 알고리즘인 plane-sweep 알고리즘을 일반화 다각형을 다룰 수 있도록 수정하고 구현한다. 이를 로보틱스이 응용분야중 하나인 고정쇠 문제(fixturing)에 적용한다.

• Journal of Korean Society for Geospatial Information Science
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• v.5 no.2 s.10
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• pp.77-85
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• 1997

Researches in the field of Computer Graphics and Geographical Information Systems(GIS) have extensively studied the method of photo-realistic landscape modelling, because it have become a commom requirement in applications such as flight simulators, mission rehearsal, and construction planning. A common approach to the display of terrain uses a Digital Elevation Model(DEM). DEM is an evenly spaced array of the terrain elevation data and can be obtained from stereo satellite data. With the DEM data, the process of 3D terrain modelling consists of three steps. The first step is to extract the meaningful data (such as peak, pit, passes...) from DEM data based on LOD(Level Of Detail) criteria. The second is to construct the 3D surface by TIN, which represents a surface as a set of non-overlapping continuous triangular facets of irregular size and shape. The third is a rendering of 3D terrain model. The goal of this research is a construction of 3D terrain with TIN. To do this, we are going to app]y Radial Sweep Algorithm. Radial Sweep Algorithm for generating TIN works quickly and efficiently. However, it does not solve the problem caused by the approximated nature of triangulated surface. To solve this problem, this research derive improved radial sweep algorithms with the optimal triangle definition.

• IE interfaces
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• v.20 no.1
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• pp.58-68
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• 2007

This research deals with a vehicle scheduling problem for the sludge collection strategies which might be solved via quantitative analysis and cost evaluations schemes. This problem can be modeled as a kind of capacitated vehicle routing pick-up problems. With the aim of establishing operation schedule of vehicles and analyzing the total cost under considering various assumptions and realistic restrictions of the sludge collection problem, we propose a heuristic method based on the genetic algorithm in conjunction with the sweep algorithm and the 4-opt algorithm. Finally, we present the cost effective operation schedule that can be used as the managing tool for the sludge treatment plant of the multi-purpose dam.