• 한국공간정보시스템학회:학술대회논문집
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• 한국공간정보시스템학회 2000년도 학술회의 논문집 3권2호
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• pp.139-153
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• 2000

지리 정보 시스템을 위한 공간 데이터베이스 관리시스템간의 이질성을 최소화하고 공간 데이터의 호환성이나 상호 연동성을 높일 수 있도록 OGC에서 OpenGIS의 사양을 정의하였다. 본 연구에서는 OpenGIS에서 정의된 공간 데이터 모델을 지원하는 컴포넌트를 구현한 것이다. 즉, OpenGIS에서 요구되어진 사양에 따라 SFG (Simple Feature Geometry) 컴포넌트를 구현하였다. 본 논문에서는 컴포넌트 구현상의 발생되었던 문제점과 이 해결 방법을 제시한다. 또한 구현 도중에 발견된 OpenGIS SFG의 사양 자체의 문제점도 함께 제시한다.

• 전자공학회논문지A
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• 제32A권11호
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• pp.52-62
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• 1995

We developed a two-dimensional numerical simulator which can analyze the electrical as well as optical characteristics and evaluate the detection performances of self-signal processing infrared detectors. It solves the poisson equation and the electron, hole current continuity equations including the optical generation and recombination models. To speed up convergency rate. the Newton algorithm is used. Automatic triangular grid generator make it easy to simulate the devices with the various read-out geometries. This simulator can show the variation of spatial resolution which is caused by the transit velocity and transit time dispersion in bifurcate and horn geometries respectively. Also, we calculated the responsivity, noise, and detectivity in respect of the applied electric field and background field-of-view. The results obtained from simulation correspond to those of experiments, and it is verified that horn read-out geometry has the superior spatial resolution and detection performance to bifurcate geometry.

• 대한수학교육학회지:수학교육학연구
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• 제9권1호
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• pp.121-132
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• 1999

We have compared Korean and American mathematics curriculums in 5 areas: whole number(concepts and its operations); geometry; pattern and relations; measurements; statistics and probability. We have found significant differences in geometry area. Korean curriculums contain simple planar figures (circles, triangles, rectangles, and squres) and some of the spatial figures until 3rd grades. But in America they learn various planar and spatial fugures(cone, pyramid, triangular prism, etc) since the 1st grade starts. They also start the 1st grade by dealing with topological concepts like open/closed, inside/outside, order, etc. As the grade goes on, students learn other geometrical concepts like congruence, symmetry, 3-dimensional views. We also found that American curriculum focuses on students' activities and courages communication through projects, groupwork, journal writing, etc. It's also superior in respects of motivation, and connections with real life and other subjects. Korean curriculum needs more improvements in these aspects. Furthermore for lower graders reviewing sections need to be enhanced for feedback.

• 한국GIS학회:학술대회논문집
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• 한국GIS학회 2004년도 GIS/RS 공동 춘계학술대회 논문집
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• pp.23-29
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• 2004

GIS 관련 산업이 발전함에 따라, 공간 데이터의 상호 운용성이라는 문제가 제기되었다. 현재, 이러한 문제점을 해결하기 위해 OGC는 공간 데이터 및 GIS에 대한 국제적인 표준을 제시하고 있다. 본 연구에서는 OGC의 Simple Features for OLE/COM 표준 사양을 준수하는 GIS 데이터제공자를 구현하여 기존의 공간 데이터베이스와 Geometry 컴포넌트간 공간 데이터에 대한 상호 운용성을 확인하고자 한다. 더 나아가 공간 데이터베이스와 Geometry 컴포넌트로 이루어지는 GIS S/W 시스템 성능 향상을 위한 GIS 데이터제공자 기반의 버퍼관리기법에 대한 설계 및 구현을 하고, 이에 대한 성능 테스트를 하고자 한다. 또한, GIS 데이터제공자 및 버퍼관리기법을 구현하여 앞으로 GIS 데이터제공자 기반의 황용 방안을 제시하고자 한다.

• 대한수학교육학회지:학교수학
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• 제3권2호
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• pp.355-372
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• 2001

The primary school mathematics emphasizes some activities such as visualizing figures, drawing figures and comparing figures from various angles. These activities could be undertaken throughout examination, experiments and exploration of the substantial materials. They could also be undertaken by using the objects found in a daily life informally. The 7th curriculum of mathematics reflects this trend and includes the systematized activities in teaching spatial sense in geometry. However, it still requires more researches on the teaching methodology of spatial sense and the conceptual analysis of spatial sense. In this study, the concept of spatial sense is analyzed and Mackim's 3-levels teaching methodology and Bruner's EIS theory and suggestions are reviewed as a possible teaching methodology of spatial tasks. As a conclusion, this study suggests a teaching-learning methodology of spatial tasks at the levels of 2-GA and 3-Ga of the 7th curriculum of mathematics.

• 한국멀티미디어학회논문지
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• 제7권12호
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• pp.1729-1736
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• 2004

This paper proposes an efficient collision detection method in the dynamic spatial subdivisions for the MMORPG engine which requires realtime interactions. An octree is a suitable structure for static scenes or terrain processing. An octree spatial subdivision enhances rendering speed of scenes. Current spatial subdivisions tend to be highly optimized for efficient traversal, but are difficult to update quickly for a changing geometry. When an object moves to the outside extent for the spatial subdivisions, the acceleration structure would normally have to be rebuilt. The OSP based on a tree is used to divide dynamically wide outside which is the subject of 3D MMORPG. TBV does not reconstruct all tree nodes of OSP and has reduced rebuilding times by TBV information of a target node. A collision detection is restricted to those objects contained in the visibility range of sight by using the information established in TBV. We applied the HBV and ray tracing for an efficient collision detection.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.59-64
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• 2002

This paper presents a method for line segment extraction for 3-d building reconstruction. Building roofs are described as a set of planar polygonal patches, each of which is extracted by watershed-based image segmentation, line segment matching and coplanar grouping. Coplanar grouping and polygonal patch formation are performed per region by selecting 3-d line segments that are matched using epipolar geometry and flight information. The algorithm has been applied to high resolution aerial images and the results show accurate 3-d building reconstruction.

• 한국콘텐츠학회논문지
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• 제15권7호
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• pp.289-299
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• 2015

본 연구의 목적은 디지털방사선시스템의 영상 품질을 비교하고 평가함에 있다. 영상의 정량적인 분해능을 나타내는 변조전달함수, 노이즈 특성을 나타내는 잡음력 스펙트럼을 이용하여 영상 품질평가를 하였다. IEC61267 선질을 사용하여 IEC62220-1에서 제시하는 기하학적인 조건과 실제 임상에서 사용되어지는 기하학적인 조건을 사용하여 부가필터 및 그리드, 임상선량을 이용하여 edge 팬텀을 사용하여 MTF값을 측정하였다. Grid, Filter, SID, kVp, mAs에 따른 MTF 결과는 임상조건 100, 180cm 와 IEC62220-1 기하학적인 조건 150cm에서 MTF 공간주파수 측정값은 비슷하게 나타났으며, 오히려 임상조건 100, 180cm에서 공간주파수가 높은 경우도 있었다. NPS 결과는 선량이 증가함에 따라 감소함을 나타내었다. IEC61267 선질을 이용한 영상품질평가에서는 IEC62220-1기하학적인 조건을 이용한 품질평가보다 임상조건 기하학적인 조건을 사용한 영상의 품질이 좋았다. IEC 와 임상조건에서의 MTF와 NPS는 크게 차이가 나지 않았음을 알 수 있었다. 그러므로 향후 IEC 표준에서 제시하는 영상품질 평가보다는 임상 조건을 적용한 영상품질 평가방법을 적용하기 위해서 부가필터사용 유 무, 그리드사용 유 무, SID변화, 선질, 선량 등의 파라메터를 적절히 이용하여 가장 적은 선량으로 공간분해능이 좋고, NPS가 감소하는 방법들을 찾는다면 향후 실제 임상에서 사용되고 있는 디지털방사선시스템을 최적의 품질로 유지할 수 있는 참고 자료로 활용될 수 있을 것으로 사료된다.

• 천문학회지
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• 제28권2호
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• pp.223-243
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• 1995

We describe the implementation of a multi-dimensional numerical code to solve the equations for idea! magnetohydrodynamics (MHD) in cylindrical geometry. It is based on an explicit finite difference scheme on an Eulerian grid, called the Total Variation Diminishing (TVD) scheme, which is a second-order-accurate extension of the Roe-type upwind scheme. Multiple spatial dimensions are treated through a Strang-type operator splitting. Curvature and source terms are included in a way to insure the formal accuracy of the code to be second order. The constraint of a divergence-free magnetic field is enforced exactly by adding a correction, which involves solving a Poisson equation. The Fourier Analysis and Cyclic Reduction (FACR) method is employed to solve it. Results from a set of tests show that the code handles flows in cylindrical geometry successfully and resolves strong shocks within two to four computational cells. The advantages and limitations of the code are discussed.

• 한국수학교육학회지시리즈A:수학교육
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• 제52권4호
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• pp.531-547
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• 2013

The purpose of the study is to examine how effects of activities using Google SketchUp on students' spatial ability and 3D geometric thinking in measuring the volume of solid figures. By comparing the results from pre- and post-tests between the experimental group and control group, we found that activities using Google SketchUp help students improve their spatial ability in the spatial orientation and visualization. In addition, more than half students in the experimental group moved from level 4 up to level 7 in thinking process of measuring the volume in terms of Battista(2004)'s levels. This study suggests that the instruction with Google SketchUp can help to improve students' spatial ability and 3D geometric thinking in the regular class in middle school. In addition, SketchUp can be an advanced technological tool to support students' self-directed learning, which create an efficient educational environment and a great opportunity to learn geometry in an effective manner.