• 제목/요약/키워드: geometric form

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기상계측 시스템을 이용한 머시닝센터의 기하오차 모델링 및 오차측정 (Modeling and Measurement of Geometric Errors for Machining Center using On-Machine Measurement System)

  • 이재종;양민양
    • 한국정밀공학회지
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    • 제16권2호통권95호
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    • pp.201-210
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    • 1999
  • One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric and thermal errors of the machine tools. Therefore, a key requirement for improving te machining accuracy and product quality is to reduce the geometric and thermal errors of machine tools. This study models geometric error for error analysis and develops on-machine measurement system by which the volumetric erors are measured. The geometric error is modeled using form shaping function(FSF) which is defined as the mathematical relationship between form shaping motion of machine tool and machined surface. The constant terms included in the error model are found from the measurement results of on-machine measurement system. The developed on-machine measurement system consists of the spherical ball artifact (SBA), the touch probe unit with a star type stylus, the thermal data logger and the personal computer. Experiments, performed with the developed measurement system, show that the system provides a high measuring accuracy, with repeatability of ${\pm}2{\mu}m$ in X, Y and Z directions.

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기하학적 접근법에 의한 교량구조의 형태생성 (Form Generation of Structural Bridges based on Geometric Approach)

  • 김남희;고현무;홍성걸
    • 한국전산구조공학회논문집
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    • 제23권4호
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    • pp.379-386
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    • 2010
  • 개념적 설계단계에서 교량형태를 자유롭게 생성하는 것이 매우 중요하다. 그러나 공학적 설계자의 입장에서는 다양한 형태를 상상하기 보다는 힘의 전달방식에 따른 구조시스템의 종류를 우선적으로 생각하게 된다. 이 연구에서는 교량형태를 기하학적 측면에서 새롭게 살펴봄으로써 기존의 공학적 접근법에서 막혔던 상상력의 한계를 확장시키고자 한다. 우선적으로 기존교량의 형태를 기하학적으로 분석하고, 기하학적 특징이 뚜렷한 교량형태에 대해서는 이 연구에서 제시하는 기하학적 접근법을 이용해서 생성해본다. 이 연구의 초점은 새로운 구조물 형태생성의 기하학적 원리를 개발하는 것이 아니라, 기존의 정립된 기하학적 원리를 이용하여 다양한 설계대안을 생성하는 접근법을 제시하고자 한다.

A Form-finding Technique for Three-dimensional Spatial Structures

  • Lee, Sang Jin
    • Architectural research
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    • 제15권4호
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    • pp.207-214
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    • 2013
  • A form-finding technique is proposed for three-dimensional spatial structures. Two-step discrete finite element (FE) mesh generator based on computer aided geometric design (CAGD) is introduced and used to control the shape of three-dimensional spatial structures. Mathematical programming technique is adopted to search new forms (or shapes) of spatial structures. For this purpose, the strain energy is introduced as the objective function to be minimized and the initial volume (or the initial weight) is considered as constraint function. Numerical examples are carried out to test the capability of the proposed form-finding techniques and provided as benchmark tests.

3차 Ball 곡선을 이용한 자유 형태 곡면 근사 방법 (The Approximation of Free-form Surface using Cubic Ball Curve)

  • 이아리;심재홍
    • 한국정보처리학회논문지
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    • 제7권4호
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    • pp.1271-1278
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    • 2000
  • A general curve and surface is a basic method to generate Free-form object using the fundamental properties of blending function. In typical method, there is an overhead of calculating to present Free-form object with the line segments and interpolation algorithm, In this paper, for resolving this problem efficiently, it will propose the flexible Free-form curves/surfaces using Ball curve shape-preserving property. This method includes Geometric Continuity that is needed to design Free-form Surface of high degree consisted with many curves. Also, when lots of data are reduced using Geometric Property of Free-form curves, the shape-preserving property of resulting object can be maintained, then it can represent any Free-form object with less calculating .

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화성암에서의 결정경계: 성인적 분류와 기하학적 특성 (Cystal Boundaries in Igneous Roks: Genetic Classification and Geometric Features)

  • Park, Youngdo
    • 암석학회지
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    • 제4권2호
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    • pp.168-177
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    • 1995
  • Crystal boundaries in igneous rocks are genetically classified in order to predict the geometric patterns of the boundaries which may aid deciphering the textural code in igneous rocks. Crystal boundaries may be formed by two end-member processes;(1) mechanical and (2) chemical removal of interstitial melt. Mechanical removal of the melt will form displacement impingement boundaries, while chemical removal of the melt will form growth impingement boundaries. The positions of boundaries relative to the material points may be affected by secondary processes such as (1) migration and (2) dissolution. The geometric features of crystal boundaries, suggested in this study, may be useful when studying igneous textures and processes, although it may be impossible to determine the suggested features with the analytical techniques currently avilable.

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파라메트릭기법을 이용한 3차원 자유곡면 생성에 관한 연구 (A Study on the Freeform Surface Generation Using Parametric Method)

  • 김태규;변문현
    • 한국CDE학회논문집
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    • 제3권4호
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    • pp.293-303
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    • 1998
  • The objective of this study is to develop a PC level freeform surface modeling system which explicitly represents information of part geometry. Surface modeler uses nonuniform rational B-spline (NURBS) function with nonuniform knot vector for the flexible modeling work. The results of this study are as follows. 1) By implementation surface modeler through applying representation scheme proposed to represent free-form surface explicity, the technical foundation to develop free-from surface modeling system using parametric method. 2) Besides the role to model geometric shape of a surface, geometric modeler is developed to model arbitrary geometric shape. By doing this, the availability of the modeling system is improved. Geometric modeler can be utilized application fields such as collision test of tool and fixture, and tool path generation for NC machine tool.

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ON THE CONSTRUCTION AND THE EXISTENCE OF PARAMETRIC CUBIC$g^2$ B-SPLINE

  • Kimn, Ha-Jine
    • 대한수학회논문집
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    • 제10권2호
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    • pp.483-490
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    • 1995
  • A parametric cubic spline interpolating at fixed number of nodes is constructed by formulating a parametric cubic $g^2$ B-splines $S_3(t)$ with not equally spaced parametric knots. Since the fact that each component is in $C^2$ class is not enough to provide the geometric smoothness of parametric curves, the existence of $S_3(t)$ oriented toward the modified second-order geometric continuity is focalized in our work.

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GENERALIZED HYPERBOLIC GEOMETRIC FLOW

  • Shahroud Azami;Ghodratallah Fasihi Ramandi;Vahid Pirhadi
    • 대한수학회논문집
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    • 제38권2호
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    • pp.575-588
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    • 2023
  • In the present paper, we consider a kind of generalized hyperbolic geometric flow which has a gradient form. Firstly, we establish the existence and uniqueness for the solution of this flow on an n-dimensional closed Riemannian manifold. Then, we give the evolution of some geometric structures of the manifold along this flow.

활주형 선박의 선형설계를 위한 통합 CAD/CAE 시스템 (Integrated CAD/CAE System for Planing Hull Form Design)

  • 김태윤;김동준
    • 수산해양기술연구
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    • 제39권4호
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    • pp.298-304
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    • 2003
  • In this paper a free-form hull design program and performance prediction program for planing boat is introduced. This program enables the designer to do complex geometric hull shape design on a personal computer and accurately to predict power requirements for a given loading and velocity. For a free form design, Bezier curve model is adopted as a basic representation tool of curves and surfaces, and this program has versatile functions to do fairing jobs with a convenient graphical user interface. After creating a hull form the geometric data is provided in a manner compatible with a variety of analysis tools including 'Motion Analysis(by Zarnick)' for prediction of motion characteristics in regular waves, 'Running Attitude (by Savitsky)' for prediction of the running attitude and required power.

대면적 가공물의 마이크로 그루빙에서 고속 절삭 깊이 제어를 통한 미세형상의 정밀도 향상 (Improvement of Form Accuracy of Micro-Features on Thin, Large-area Plate using Fast Depth Adjustment in Micro-grooving)

  • 강동배;손성민;이효렬;안중환
    • 한국생산제조학회지
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    • 제22권3호
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    • pp.408-413
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    • 2013
  • Micro-features such as grooves and lenses, which perform optical functions in flat displays, should be manufactured with a good form accuracy because this is directly related to their optical performance. As the size of the display increases, it is very difficult to maintain a high relative accuracy because of the inherent geometric errors such as the waviness of a large-area plate. In this paper, the optical effect of these geometric errors is investigated, and surface-referenced micro-grooving to measure and compensate for such geometric errors on line is proposed to improve the form accuracy of the micro-grooves. A PZT-based fast depth adjustment servo system is implemented in the tool holder to maintain a uniform groove depth in reference to the wavy surface. Through experiments, the proposed method is shown to be an efficient way to produce high-quality micro- grooves on a wavy die surface.