• Journal of Educational Research in Mathematics
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• v.19 no.4
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• pp.531-543
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• 2009

This study identified what cognitive attributes are required of eighth graders to solve geometrical problems such as 'Recall,' 'Analyze,' 'Justify,' 'Synthesize/Integrate,' and 'Solve Non-routine Problems' by using the cognitive diagnostic theory. The five attributes are proved as the skills for solving the geometric problems. Many students have not fully mastered the attributes of 'Justify' and 'Synthesize/Integrate'. There was high correlation between these attributes. 'Analyze' best predicted the changes in the geometric achievement. And while students with high levels of geometrical achievement have mastered all the five attributes, those in the mid- and low-level range of performance have mastered fewer attributes.

• The KIPS Transactions:PartA
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• v.11A no.5
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• pp.365-372
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• 2004

Recently, the studies for mesh simplification have been increased according to the application area of the complicate 3D mesh models has been expanded. This paper introduces a novel method for mesh simplification which uses the properties of the mesh model in addition to the geometric locations of the model. The information of the 3D mesh model Includes surface properties such as color, texture, and curvature information as well as geometic information of the model. The most of current simplification methods adopt such geometric information and surface properties individually for mesh simplification. However, the proposed simplification method combines the geometric information and solace properties and applies them to the simplification process simultaneously. In this paper, we exploit the extended geometry based quadric error metric(QEM) which relatively allows fast and accurate geometric simplification of mesh. Thus, the proposed mesh simplification utilizes the quadric error metric based on geometric information and the surface properties such as color, normal, and texture. The proposed mesh simplification method can be expressed as a simple quadric equation which expands the quadric error metric based on geometric information by adding surface properties such as color, normal, and texture. From the experimental results, the simplification of the mesh model based on the proposed method shows the high fidelity to original model in some respects such as global appearance rather than using current geometry based simplification.

• The KIPS Transactions:PartD
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• v.8D no.5
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• pp.516-572
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• 2001

Geographic Information System(CIS) deal with data which can potentially be useful for a wide range of applications. The information needed by each application can be vary, specially in resolution, detail level, application view, and representation style, as defined in the modeling phase of the geographic database design. To be able to deal with such diverse needs, GIS must offer features that allow multiple representation for each geographic entity of phenomenon. This paper addresses on the problem of formal definition of the objects and their relationships on the geographical information systems. The geographical data is divided into two main classes : geo-objects and geo-fields, which describe discrete and continuous representations of spatial reality. I studied the attributes and the relationship roles over geo-object and nongeo-object. Therefore, this paper contributed on the efficient design of geographical class hierarchy schema by means of formalizing attribute-domains of classes.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.11a
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• pp.143-146
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• 2000

본 논문에서는 다수의 실내 영상으로부터 영상을 촬영한 카메라의 속성정보와 실내 환경에 대한 기하정보를 추출하는 방법을 제안한다. BSP-Tree를 이용하여 주어진 실영상을 각각의 부분 영역이 실제로도 평면 영역에 해당되도록 분할하였으며, 특징점 대응을 통해 각 분할된 영역의 영상간 대응을 찾고 이로부터 각 분할 영역의 homography를 계산하였다 또한 간단한 가정을 통해 계산된 homography로부터 각 분할영역에 대응된 평면의 방정식과 각 영상을 촬영한 카메라의 속성을 찾아낼 수 있믐을 보였다. 본 논문에서 제안한 방법은 현재 본 연구팀이 구현 중인 영상기반 모델링 시스템에서 핵심적인 기능을 수행하리라 기대된다.

• Broadcasting and Media Magazine
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• v.26 no.2
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• pp.31-45
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• 2021

본 고는 ISO/IEC JTC 1/SC 29/WG 7 MPEG(Moving Picture Experts Group) 3DG(3D Graphics coding) 그룹에서 진행되고 있는 포인트 클라우드 데이터 압축 표준 기술 중 하나인 G-PCC(Geometry-based Point Cloud Compression) 표준에 대하여 설명하고자 한다. G-PCC는 포인트 클라우드의 기하 정보와 속성 정보를 3차원 공간에서 서로 다른 기술을 이용하여 압축하는 표준으로, 무손실 압축 방법의 경우 10:1의 압축율을 제공하고 손실 압축의 경우 35:1 정도의 압축율을 보인다. 본 고에서는 G-PCC의 기하 정보와 속성 정보의 압축 방법을 상세히 설명하고 같은 기능을 수행하는 압축 기술 간의 성능을 비교하고자 한다.

• Tunnel and Underground Space
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• v.25 no.5
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• pp.450-461
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• 2015

Extensive numerical experiments have been carried out to investigate effect of block size and fracture geometry on hydraulic characteristics of fractured rock masses based on connected pipe flow in DFN systems. Using two fracture sets, a total of 72 2-D fracture configurations were generated with different combinations of fracture size distribution and deterministic fracture density. The directional block conductivity including the theoretical block conductivity, principal conductivity tensor and average block conductivity for each generated fracture network system were calculated using the 2-D equivalent pipe network method. There exist significant effects of block size, orientation, density and size of fractures in a fractured rock mass on its hydraulic behavior. We have been further verified that it is more difficult to reach the REV size for the fluid flow network with decreasing intersection angle of two fracture sets, fracture plane density and fracture size distribution.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.5
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• pp.764-771
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• 2018

This study focused on shape attributes in a basic study that identified infographics expression diversification and delivery efficiency based on formative attributes. To achieve that goal, formative attributes were categorized as geometric or expressional type, and significant differences between them were found by identifying the attributes of each type. The study analyzed the correlations between each infographic type's formative attributes and content delivery. The results found that regularity, clarity, visibility, and content delivery were attributes of the geometric type, whereas expressionality, visibility, clarity, and content delivery were attributes of the expressional type. Further analysis of the attributes focusing on content delivery found that regularity and visibility significantly influenced content delivery for the geometric type, and expressionality and clarity significantly influenced content delivery for the expressional type. Thus, this study empirically confirmed that formative attributes of infographics distinguished between expression types with statistically significant differences during the visualization process. And that specific factors influencing content delivery were formative attributes.

• The Journal of the Korea Contents Association
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• v.7 no.6
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• pp.52-59
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• 2007

This paper presents a greedy method for user-steered mesh segmentation, which is based on the merging priority metric defined for representing the geometric properties of meaningful parts. The priority metric is a weighted function composed of five geometric parameters: distribution of Gaussian map, boundary path concavity, boundary path length, cardinality, and segmentation resolution. This scheme can be extended without any modification only by defining more geometric parameters and adding them. Our experimental results show that the shapes of segmented parts can be controlled by setting up the weight values of geometric parameters.

• Tunnel and Underground Space
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• v.12 no.1
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• pp.10-18
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• 2002

Rock joint system makes a heavy effect on the behavior of rock structures. The definition of a 3D rock joint system is very important in 2D or 3D numerical analysis for the prediction of the behavior of a discontinuous rock mass. To enhance the reality of a 3D definition of rock joint system, it is essential to estimate the unbiased statistics of basic geometric attributes of rock joints. In this study, we have proposed the statistical analysis and derived the related equations for an estimation of statistics of joint size and intensity. Geometry of rock joints in 3 dimensional space can be defined by the aggregate of location, size, orientation and intensity. The dimensional limit of survey method and its data makes 3D geometric attributes probabilistic. In the estimation of statistics of joint size, we have discussed the technique to correct the bias from a dimensional limit and derived the equation of 3D joint intensity by stereological approaches.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.978-989
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• 1995

현실적으로 다속성 의사결정(Multi-Attribute Decision-Making:MADM)문제들은 대안과 속성의 수가 매우 많은 것이 보통이기 때문에 이것을 모두 합리적으로 고려하여 최적의 대안을 선정한다는 것은 매우 어려운 일이다. 지금까지 연구 개발된 기존의 수리적 방법들은 주어진 문제에 대한 제약을 가하여 최적해(optimal solution)를 구할 수 있지만 의사결정자들의 입장을 정확히 반영하지 못하는 경우가 대부분이며, 이를 개선하기 위한 기존의 대화형 접근방법은 고려해야 할 대안과 속성의 수가 많아지면 대안 간의 쌍비교등을 통하여 의사결정자가 제공해야 하는 정보의 양이 기하급수적으로 증가한다는 어려움과 함께 최적해가 보장되지 못하는 문제점이 있다. 따라서, 본 연구의 목적은 대안과 속성의 수가 매우 큰 의사결정상황 하에서 의사결정자가 중요하다고 생각하는 속성의 그룹부터 단계적으로 고려해 가면서 대안의 수를 점차적으로 감소시킬 수 있는 보다 효율적인 대화형 접근방법을 구축하는데 있다.