• Geophysics and Geophysical Exploration
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• v.2 no.4
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• pp.191-201
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• 1999

The interpretation of resistivity data has, so far, mainly been made under the assumption that the earth is of relatively simple structure and then using one or two-dimensional inversion scheme. Since real earth structure and topography are fully three-dimensional and very complicated In nature, however, such assumptions often lead to misinterpretation of the earth structures. In such situations, three-dimensional inversion is probably the only way to get correct image of the earth. In this study, we have developed a three-dimensional inversion code using the finite element solution for the forward problem. The forward modeling algorithm simulates the real field situation with irregular topography. The inverse problem is solved iteratively using the least-squares method with smoothness constraint. Our inversion scheme employs ACB (Active Constraint Balancing) to enhance the resolving power of the inversion. Including Irregular surface topography in the inversion, we can accurately define the earth structures without artifact in the numerical tests. We could get reasonable image of earth structure by Inverting the real field data sets taken over highway bridge construction site.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.10
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• pp.2617-2629
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• 1995

The flow through a centrifugal compressor rotor was calculated using the quasi-3-dimensional and fully 3-dimensional Navier-Stokes solution methods. The calculated results, obtained during the development of the computer codes for both methods are discussed. In the inviscid quasi 3-dimensional analysis, stream function formulation was used for the blade to blade (B-B) plane calculations, and the streamline curvature method was used for the meridional (H-S) plane calculations. In the viscous 3-dimensional flow analysis, a control volume method based on a general rotating curvilinear coordinate system was used to solve the time-averaged Navier-Stokes equations, and a standard k-.epsilon. model was used to obtain eddy viscosity. The quasi-3-dimensional analysis reasonably predicts the pressure distributions and requires much less computation time in the region where viscous effects are not strong; however, it fails to predict velocity field and loss mechanism through the impeller passage. The viscous 3-dimensional flow analysis shows reasonable pressure distributions and typical jet-wake flow field through the impeller passage. Secondary flow and total pressure distributions on cross-sectional planes explain the loss mechanisms through the impeller.

• The KIPS Transactions:PartB
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• v.16B no.1
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• pp.47-54
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• 2009

Automatic object recognition in 3D measuring data is of great interest in many application fields e.g. computer vision, reverse engineering and digital factory. In this paper we present a software tool for a fully automatic object detection and parameter estimation in unordered and noisy point clouds with a large number of data points. The software consists of three interactive modules each for model selection, point segmentation and model fitting, in which the orthogonal distance fitting (ODF) plays an important role. The ODF algorithms estimate model parameters by minimizing the square sum of the shortest distances between model feature and measurement points. The local quadric surface fitted through ODF to a randomly touched small initial patch of the point cloud provides the necessary initial information for the overall procedures of model selection, point segmentation and model fitting. The performance of the presented software tool will be demonstrated by applying to point clouds.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11b
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• pp.675-680
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• 2003

현재 인터넷상에서 서비스되고 있는 컨텐츠는 업그레이드되어 3차원 가상기법인 Web 3D 기술을 적용한 사실적이며 현실감 있는 환경에서 상호작용이 가능한 컨텐츠로 전환되고 있다. 이에 Web 3D의 시장에 많은 저작도구들이 개발되고 활용되고 있다. VRML를 기반으로 하는 표준 기술과 특정분야에 활용될 수 있게 개발된 비표준 기술들로 발전하고 있는 환경에서 Web 3D 컨텐츠 구축을 위한 저작도구의 분석은 필연적이라 생각된다. Web 3D 저작도구의 기본 기능과 확장성, 호환성, 적용분야를 비교 분석하여 각 활용분야와 체형에 맞는 저작도구의 선택을 통한 컨텐츠 제작 효율의 극대화를 제안한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.929-934
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• 2004

As 3D scanner develops, it can be used in measurement. To accomplish complete 3D measurement, the scanner has to view different sides of the target. It can be done by moving the scanner and fix it at every measuring point. By human, it would take so much time. However, by using robot, measuring time can be reduced and the procedure can be automated. It is suitable for 6R serial manipulator to do this kind of work in which the scanner should go any position in arbitrary orientation. We did inverse kinematics analysis by analytical and graphical methods. Then, we compared two methods.

• Spatial Information Research
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• v.18 no.1
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• pp.57-67
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• 2010

Recently, 2D GIS technology is applied for urban facility management. However, urban facilities are located in 3D space and the information loss is occurring during data abstraction from 3D urban facility to 2D object. Also, the number of urban facilities is increasing steadily and most of urban facilities are located in underground space in the city. Therefore 2D urban facility management system has a limitation on visualization and management for a large number of urban facilities. In this paper, a multi-dimensions urban facility management system based on multi-texture technology is proposed. The proposed system reduces the information loss and improves the readability of information by visualizing urban facilities on 3D virtual space. A multi-texturing technology is applied for integrating of 2D vector data and 3D raster data, and a multi-thread technology is used for improving speed and performance of the system. The proposed technology can be used as a guideline for urban facility monitoring as providing visual information of a facility status with 3D image and facility data.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.2
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• pp.141-151
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• 2003

Railway bridges are subject to dynamic loads generated by the interaction between moving vehicles and the bridge structures. These dynamic loads result in response fluctuations in bridge members. To investigate the real dynamic behavior of the bridge, therefore, a number of analytical and experimental Investigations should be carried out. In this paper, a train/track/bridge interaction analysis program for evaluating the dynamic characteristics of bridges due to KTX operation in terms of structural safety, operational safety and passenger comfort is developed. To build a practical model of train/track/bridge, Hertzian spring for wheel/rail contact modeling and Winkler element for ballast are applied. This program also used torsional degree of freedom and constraint equation based on geometrical relationship in order to take into consideration three-dimensional eccentricity effect due to the operation on double track through quasi-three dimensional analysis. To verify the developed Program, comparison has been made between the measured results and those of simulation of the typical PSC box bridge(2@40m=80m) of the KHSR bridges.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06c
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• pp.350-352
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• 2012

최근 의료 분야 소프트웨어가 발전함에 따라 3차원 가상 모델을 이용한 의료 소프트웨어의 개발도 꾸준히 증가하는 추세이다. 치열 교정 분야는 이러한 3차원 가상 모델을 적용할 수 있는 분야 중 하나이다. 치열교정 분야에서는 3차원 가상 모델을 이용하여 부정 교합 환자의 치료 초기부터 끝까지 여러 단계의 치아이동 과정을 제공한다. 치아 이동의 각 단계별로 Stereolithographic Model이 만들어지는데, 이는 투명하고 얇은 Overlay 장치를 제작하는 기초가 된다. 투명한 재질의 Overlay 장치는 심미적이고 사용이 간편하여 많은 환자들이 선호하고 있다. Overlay 장치를 제작하는 시스템을 구축한 회사로는 Invisalign System이 가장 대표적이다. Invisalign System은 미국에 본사를 둔 회사로 한국에 지사를 두고 적극적인 마케팅을 통해 3D 치열 교정 분야의 국내시장을 거의 독점하고 있다. 독점적이다 보니 비용이 다른 교정 치료보다 2배 가까이 들고 있지만, 현재 한국에서는 개발이 적극적으로 이루어지지 않는 실정이다. 이에 본 논문에서는 환자 치아의 정확하고 과학적인 진단자료를 얻어 높은 치료비용에 대한 개선과 치료 전 과정에 대한 시뮬레이션 및 Stereolithographic Model을 미리 환자에게 제공하여 만족도를 높일 수 있는 3D치열 교정 시스템을 제안한다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.3
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• pp.319-326
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• 1985

본 연구에서는 준 3차원 유한요소법(quasi 3-D finite element method)을 사 용하여 균일한 변위하중뿐 아니라 적층판의 제작 공정상 필연적인 열하중(thermal loading)의 영향을 동시에 고려하여 층간균열의 발생 및 성장에 대한 특성을 밝히고자 한다. 끝으로 층간 균열이 인장강도에 미치는 영향을 혼합법칙(rule of mixtures)의 개념을 사용하여 평가하고자 한다.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.290-292
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• 1993

In this paper, analysis of the noise induced by rotating machines and the mode analysis of a 3-dimensional enclosure are presented. Adaptive active noise control algorithms for the multi-channel case are proposed. Computer simulations were done to show usefulness of the designed algorithm in a 3-dimensional enclosure case.