• 한국CDE학회논문집
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• 제6권1호
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• pp.24-30
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• 2001

An efficient and robust algorithm to compute the exact Voronoi diagram of a circle set is presented. The circles are located in a two dimensional Euclidean space, the radii of the circles are non-negative and not necessarily equal, and the circles are allowed to intersect each other. The idea of the algorithm is to use the topology of the point set Voronoi diagram as a seed so that the correct topology of the circle set Voronoi diagram can be obtained through a number of edge flipping operations. Then, the geometries of the Voronoi edges of the circle set Voronoi diagram are computed. In particular, this paper discusses the topological aspect of the algorithm, and the following paper discusses the geometrical aspect. The main advantages of the proposed algorithm are in its robustness, speed, and the simplicity in its concept as well as implementation. Since the algorithm is based on the result of the point set Voronoi diagram and the flipping operation is the only topological operation, the algorithm is always as stable as the Voronoi diagram construction algorithm of a point set.

• 대한수학회지
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• 제39권1호
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• pp.31-49
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• 2002

An R$^{n}$ -geometry (P$^{n}$ , L) is a generalization of the Euclidean geometry on R$^{n}$ (see Def. 1.1). We can consider some topologies (see Def. 2.2) on the line set L such that the join operation V : P$^{n}$ $\times$ P$^{n}$ \ $\Delta$ longrightarrow L is continuous. It is a notable fact that in the case n = 2 the introduced topologies on L are same and the join operation V : P$^2$ $\times$ P$^2$ \ $\Delta$ longrightarrow L is continuous and open [10, 11]. It is a fundamental topological property of plane geometry, but in the cases n $\geq$ 3, it is no longer true. There are counter examples [2]. Hence, it is a fundamental problem to find suitable topologies on the line set L in an R$^{n}$ -geometry (P$^{n}$ , L) such that these topologies are compatible with the incidence structure of (P$^{n}$ , L). Therefore, we need to study the topologies of the line set L in an R$^{n}$ -geometry (P$^{n}$ , L). In this paper, the relations of such topologies on the line set L are studied.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.885-890
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• 2002

As Geographic Information Systems represents three-dimensional topological Information, the systems provide accurate and delicate services for user. In order to execute three-dimensional topological operations, a dimensional transformation and heterogeneous spatial models should be used. However, the existing systems that use the dimensional transformation and the heterogeneous models, are not only difficult to operate the spatial operators, but also happened to support non- interoperability. Therefore, in order to support the spatial operation as well as interoperability between dimensions, we propose three-dimensional spatial operators for the proposed models. We defined the three-dimensional spatial operators prior to designing the proposed model. We also implemented the operators of proposed model and evaluated the implemented model on the component environment. Finally, the proposed model is able to not only support interoperability among systems but also execute spatial queries efficiently on three-dimensional spatial objects.

• 한국생산제조학회지
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• 제5권2호
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• pp.20-28
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• 1996

Compound surface modeling is widely used for die cavities and punches. A compound surface is defined in 3-D space by specifying the topological relationship of several anlytic surface elements and a sculptured surface. A constructive solid gemonetry scheme is employed to model the analytic compound surface. the desired compound surface can be accomplished by specifying topological reationship in terms of boolean relations between pimitives and the sculptured surfaces. Additionally, a method is presented for checking and avoiding the tool interference occuued in machining the compound surface. Using this method. the interference of concave, convex, and side region can be checked easily and avoided rpapidly.

• 한국농촌건축학회논문집
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• 제13권2호
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• pp.63-70
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• 2011

Despite the high historical and topological values, closed schools are rarely reutilized. The reason can be likely explained by integrity of the building structure and unawareness of the operation and maintenance for closed schools. The purpose of this study is finding a possibility of reusing closed schools by deploying SI (Skeleton and Infill) theory. SI theory is separating the "skeleton" like structure from "infill" such as interior furnishings to extend building life without complete demolishing of the building. It will allow satisfying various local community demands by alternating infill without demolishing of historical and topological value of the building. The experimental test was undertaken with closed school for this study. The local community's demands or opinions were reflected to develop a strategy for deploying infill system especially movable storage furniture to closed school. The study finds possibilities that SI theory can assist local community to 1) construct potential demand for utilizing closed school and 2) suggest strategy for operating and maintaining closed school.

• East Asian mathematical journal
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• 제22권2호
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• pp.131-149
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• 2006

In this paper we introduce the concept of $\gamma$-preopen sets in a topological space together with its corresponding $\gamma$-preclosure and $\gamma$-preinterior operators and a new class of topology $\tau_{{\gamma}p}$ which is generated by the class of $\gamma$-preopen sets. Also we introduce $\gamma$-pre $T_i$ spaces(i=0, $\frac{1}{2}$, 1, 2) and study some of its properties and we proved that if $\gamma$ is a regular operation, then$(X,\;{\tau}_{{\gamma}p})$ is a $\gamma$-pre $T\frac{1}{2}$ space. Finally we introduce $(\gamma,\;\beta)$-precontinuous mappings and study some of its properties.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권2호
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• pp.79-85
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• 2001

In this paper, a novel Zero-Current-Transition (ZCT) technique, which provides Zero-Current-Switching (ZCS) turn-off of the main switch, the main diode and the auxiliary switch, is presented. The proposed auxiliary circuit consists of minimum elements only one auxiliary switch, resonant inductor and resonant capacitor. Also the reduced di/dt, which is obtained by resonant inductor, helps soft turn-on of the main switch. Besides, to eliminate the additional conduction loss and current stress on main switch, a topological variation was performed. The theoretical analysis and the operation principle of the new ZCT techniques are described in detail with a boost converter as an example. To verify the validity of the proposed ZCT techniques, the simulation and the experiment were performed under 1kW output power and 100kHz switching frequency.

• Kyungpook Mathematical Journal
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• 제61권1호
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• pp.61-74
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• 2021

Let G = (V, E) be a connected graph. The eccentric connectivity index of G is defined by ��C (G) = ∑u∈V (G) deg(u)e(u), where deg(u) and e(u) denote the degree and eccentricity of the vertex u in G, respectively. In this paper, we introduce a new formulation of ��C that will be called the distance eccentric connectivity index of G and defined by $${\xi}^{De}(G)\;=\;{\sum\limits_{u{\in}V(G)}}\;deg^{De}(u)e(u)$$ where degDe(u) denotes the distance eccentricity degree of the vertex u in G. The aim of this paper is to introduce and study this new topological index. The values of the eccentric connectivity index is calculated for some fundamental graph classes and also for some graph operations. Some inequalities giving upper and lower bounds for this index are obtained.

• 한국지역지리학회지
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• 제6권3호
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• pp.83-99
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• 2000

이 논문의 연구목적은 초등학교 아동의 사회 교과서 내용 중 지리영역 학습내용구성의 개선에 기여할 수 있는 기초자료를 제공하는 데 있다. 이러한 목적을 위하여 공간인지발달이론을 초등학교 학생의 그림분석을 통해 검증하였다. 분석의 결과, 공간의 조작능력은 연령의 종가와 더불어 형상적 공간에서 투영적 공간을 거쳐 기하학적 공간을 조작하는 과정으로 진행됨을 알 수 있었다. 이는 피아제와 인헬데르의 인지발달이론에서 주장하는 바와 일치하였다. 그러나 그들이 제시한 각 조작기별 해당 연령은 실제와 비교하면 조작기 구분의 엄밀한 기준이 되지 않음을 보여 주었다. 그 이유는 같은 연령의 아동간에도 현격한 개인차를 지니기 때문이다. 이와 같은 연구의 결과는 지리 교육적으로 다음과 같은 시사점을 제공한다: 첫째, 초등학교 3학년 교과서의 내용 중 사진과 그림지도와 삽화 등이 아동의 지적 수준에 맞는지 의문스럽다. 둘째, 3학년 아동에게 그림지도를, 4학년 아동에게 실측도와 유사한 지도를 직접 그리게 하는 것은 기하학적 공간의 조작에 속하므로 큰 무리가 따른다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.880-884
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• 2002

According to the development of computer technology, especially in 3D graphics and visualization, the interest for 3D GIS has been increasing. Several commercial GIS softwares are ready to provide 3D function in their traditional 2D GIS. However, most of these systems are focused on visualization of 3D objects and supports few analysis functions. Therefore in this paper, we design not only a spatial operation processor which can support spatial analysis functions as well as 3D visualization, but also implement a prototype to operate them. In order to support interoperability between the existing models, the proposed spatial operation processor supports the 3D spatial operations based on 3D geometry object model which is designed to extend 2D geometry model of OGIS consortium, and supports index based on R$^*$-Tree. The proposed spatial operation processor can be applied in 3D GIS to support 3D analysis functions.