• Title/Summary/Keyword: Geometric Modeling

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Geometric Constraint Management for Sweeping and Boolean Operations (스위핑과 불리언 연산에 대한 형상 구속조건 관리)

  • 김웅주;정채봉;김재정
    • Korean Journal of Computational Design and Engineering
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    • v.5 no.4
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    • pp.301-311
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    • 2000
  • For effective part modifications which is necessary in the design process frequently, variational geometric modeling with constraint management being used in a wide. Most variational geometric modeling methods, however, manage just the constraints about sketch elements used for generation of primitives. Thus, not only constraint propagation but also re-build of various modeling operations stored in the modeling history is necessary iota part geometry modifications. Especially, re-build of high-cost Boolean operations is apt to deteriorate overall modeling efficiency abruptly. Therefore, in this paper we proposed an algorithm that can handle all geometric entities of the part directly. For this purpose, we introduced eight type geometric constraints to the various geometric calculations about all geometric entities in sweepings and Boolean operations as well as the existing constraints of the sketch elements. The algorithm has a merit of rapid part geometric modifications through only constraint propagation without rebuild of modeling operations which are necessary in the existing variational geometric modeling method.

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Verification of the Standard Modeling Commands by Implementing a Geometric Modeler (형상 모델러의 구현을 통한 표준 모델링 명령어 집합의 검증)

  • 김병철;한순흥
    • Korean Journal of Computational Design and Engineering
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    • v.9 no.1
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    • pp.19-26
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    • 2004
  • It is not possible to exchange parametric information of CAD models based on the current version of STEP (Standard for the Exchange of Product model data). The designer intents are lost during the transfer of CAD models. To resolve this problem, the macro-parametric approach had been proposed. To enable this approach, a set of standard modeling commands has been defined. Errors or missing elements of the standard modeling commands can be discovered by implementing macro-parametric translators. But there is a limit to discover problems only by using translators. This paper proposes a method to verify the standard modeling commands by implementing a geometric modeler. First, each argument of a modeling command is verified. Second, the set of the standard modeling commands is applied to geometric modeling of commercially available product parts. For the geometric modeling, nine test models have been selected.

Geometric Modeling of Linear Pushbroom Images : SPOT5 Images

  • Koo, Ja-Hyuck;Jung, Hyung-Sup;Lee, Ho-Nam
    • Proceedings of the KSRS Conference
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    • pp.1165-1167
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    • 2003
  • Geometric corrections are required to compensate skew effects, earth rotation effects and so on. Parameters for geometric modeling can be acquired from the metadata information. These parameters allow to locate on ground every pixel of acquired images. In this paper, we tested the precision of geometric modeling of linear pushbroom images, acquired by SPOT 3 and 5 using the satellite orbit information itself without additional external data. The result acquired from examination to recovery the geometry of image using 30 GCPs have about 650m RMSE in SPOT 3 and about 170m RMSE in SPOT 5.

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A Survey: application of geometric modeling techniques to ship modeling and design

  • Ko, Kwang-Hee
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.2 no.4
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    • pp.177-184
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    • 2010
  • In this study, geometric modeling techniques and their application to ship modeling and design are presented. Traditionally the hull shape is defined by using curves called the lines and various necessary computations are performed based on the discrete points obtained from the lines. However, some applications find difficulty in using the lines such as seakeeping analysis, which requires the computation of wetted part that is changing dynamically over time. To overcome such a problem and increase accuracy and efficiency in computation, two essential geometric modeling techniques, surface modeling and surface-to-surface intersection, are introduced and their application to ship modeling and analysis including hydrostatic computation, slamming and seakeeping analyses is presented.

Geometric Modeling of Thin-film Thickness Profile for the OLED Evaporation Process (유기 증착 공정을 위한 박막 형상 모델링 EL)

  • 이응기
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.1444-1447
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    • 2004
  • For the OLED evaporation process, thin film thickness uniformity is of great practical importance. In order to achieve the better thickness uniformity, geometric simulation of film thickness distribution profile is required. In this paper, a geometric modeling algorithm is introduced for process simulation of full-color OLED evaporating system. The physical fact of the evaporation process is modeled mathematically. Based on the developed method, the uniformity of the organic layer thickness can be successfully controlled.

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Dynamic Modeling Method for Beams Undergoing Overall Rigid Body Motion Considering Two Geometric Non-linear Effects (두 기하학적 비선형 효과들을 고려한 대변위 강체운동을 하는 보의 동적 모델링 방법)

  • Kim, Na-Eun;Yoo, Hong-Hee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.6
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    • pp.1014-1019
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    • 2003
  • A dynamic modeling method for beams undergoing overall rigid body motion is presented in this paper. Two special deformation variables are introduced to represent the stretching and the curvature and are approximated by the assumed mode method. Geometric constraint equations that relate the two special deformation variables and the cartesian deformation variables are incorporated into the modeling method. By using the special deformation variables, all natural as well as geometric boundary conditions can be satisfied. It is shown that the geometric nonlinear effects of stretching and curvature play important roles to accurately predict the dynamic response when overall rigid body motion is involved.

Feature-Based Non-manifold Geometric Modeling System to Provide Integrated Environment for Design and Analysis of Injection Molding Products (사출 성형 제품의 설계 및 해석의 통합 환경을 제공하기 위한 특징 형상 기반 비다양체 모델링 시스템의 개발)

  • 이상헌;이건우
    • Korean Journal of Computational Design and Engineering
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    • v.1 no.2
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    • pp.133-149
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    • 1996
  • In order to reduce the trial-and-errors in design and production of injection molded plastic parts, there has been much research effort not only on CAE systems which simulate the injection molding process, but also on CAD systems which support initial design and re-design of plastic parts and their molds. The CAD systems and CAE systems have been developed independently with being built on different basis. That is, CAD systems manipulate the part shapes and the design features in a complete solid model, while CAE systems work on shell meshes generated on the abstract sheet model or medial surface of the part. Therefore, it is required to support the two types of geometric models and feature information in one environment to integrate CAD and CAE systems for accelerating the design speed. A feature-based non-manifold geometric modeling system has been developed to provide an integrated environment for design and analysis of injection molding products. In this system, the geometric models for CAD and CAE systems are represented by a non-manifold boundary representation and they are merged into a single geometric model. The suitable form of geometric model for any application can be extracted from this model. In addition, the feature deletion and interaction problem of the feature-based design system has been solved clearly by introducing the non-manifold Boolean operation based on 'merge and selection' algorithm. The sheet modeling capabilities were also developed for easy modeling of thin plastic parts.

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Boolean Operation of Non-manifold Model with the Data Structure of Selective Storage (선택저장 자료구조를 이용한 복합다양체 모델의 불리언 작업)

  • 유병현;한순흥
    • Korean Journal of Computational Design and Engineering
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    • v.5 no.4
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    • pp.293-300
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    • 2000
  • The non-manifold geometric modeling technique is to improve design process and to Integrate design, analysis, and manufacturing by handling mixture of wireframe model, surface model, and solid model in a single data structure. For the non-manifold geometric modeling, Euler operators and other high level modeling methods are necessary. Boolean operation is one of the representative modeling method for the non-manifold geometric modeling. This thesis studies Boolean operations of non-manifold model with the data structure of selective storage. The data structure of selective storage is improved non-manifold data structure in that existing non-manifold data structures using ordered topological representation method always store non-manifold information even if edges and vortices are in the manifold situation. To implement Boolean operations for non-manifold model, intersection algorithm for topological cells of three different dimensions, merging and selection algorithm for three dimensional model, and Open Inventor(tm), a 3D toolkit from SGI, are used.

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Verification of STL Using the Triangle Based Geometric Modeling (삼각형기반 형상모델러를 이용한 STL의 검증)

  • 채희창;황동기
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.578-582
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    • 1996
  • Verification of STL is essential in RP. In the study, triangle based non-manifold geometric modeling that can check intersection between triangles was used to vilify STL. The method proposed in this study can be applied at the most general case and very useful, but has a penalty on computing thime of O(n$^2$)

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Three extended geometric process models for modeling reliability deterioration and improvement

  • Jiang, R.
    • International Journal of Reliability and Applications
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    • v.12 no.1
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    • pp.49-60
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    • 2011
  • The geometric process (GP) has been widely used for modeling failure and repair time sequences of repairable systems. The GP is mathematically tractable but restrictive in reliability applications since it actually assumes that the mean function of inter-failure times sequence asymptotically decreases to zero; and the mean function of successive repair times sequence asymptotically increases to infinity. This is generally unrealistic from an engineering perspective. This paper presents three extended GP models for modeling reliability deterioration and improvement (or growth) process. The extensions maintain the advantage of mathematical tractability of GP model. Their usefulness and appropriateness are illustrated with three real-world examples.

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