• 제목/요약/키워드: NUBS

검색결과 10건 처리시간 0.026초

스플라인 곡면 모델링과 쉘 유한요소와의 연동 가시화 (Visualization of Integration of Surface Geometric Modeling and Shell Finite Element Based on B-Spline Representation)

  • 조맹효;노희열;김현철
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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    • pp.505-511
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    • 2002
  • In the present study, we visualize the linkage framework between geometric modeling and shell finite element based on B-spline representation. For the development of a consistent shell element, geometrically exact shell elements based on general curvilinear coordinates is provided. The NUBS(Non Uniform B-Spline) is used to generate the general free form shell surfaces. Employment of NUBS makes shell finite element handle the arbitrary geometry of the smooth shell surfaces. The proposed shell finite element .model linked with NUBS surface representation provides efficiency for the integrated design and analysis of shell surface structures. The linkage framework can potentially provide efficient integrated approach to the shape topological design optimizations for shell structures.

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Non Uniform B-spline(NUB) 곡면에 의한 블랜드 곡면의 모델링 (Modeling of blend surfaces by Non Uniform B-spline surface patches)

  • 유우식;정회민
    • 대한산업공학회지
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    • 제26권2호
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    • pp.95-100
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    • 2000
  • Presented in this paper is a scheme for constructing ball rolling blends of a non-uniform B-spline surface(NUBS) patches. Ball rolling blending is a popular technique for blending between parametric surfaces. Along the "common edge" of a pair of "base surfaces" to be blended, a sequence of "ball positions" is sampled. The radius of the ball may vary along the line. At each sampling point, a ball center point and a pair of ball contact points are computed by applying a Jacobian inversion method. Using ball contact points, the constructing scheme of blend NUBS patches consists three steps; 1) determination of intermediate control vertices; 2) determination of boundary vectors; 3) determination of B-spline control vertices. The proposed blending scheme has been tested in a Omega CAM system and found to be working satisfactorily.

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다항식회귀분석을 통한 임펠러의 역공학 적용에 관한 연구 (Study on Application of Reverse Engineering of Impeller using Polynomial Regression)

  • 윤상환;황종대;정윤교
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2003년도 춘계학술대회 논문집
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    • pp.1776-1779
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    • 2003
  • This research presents Reverse Engineering of a Impeller. The modeling introduced in this paper adopts polynomial regression that is utilizing approximating technique. The measured data are obtained from measuring with Coordinate Measuring Machine. This paper introduces efficient methods of Reverse Engineering using Polynomial Regression.

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NURBS 보간의 적용 (Implementation of NURBS interpolator)

  • 최인휴;양민양;이강주;김찬봉
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2002년도 추계학술대회 논문집
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    • pp.51-54
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    • 2002
  • This paper deals with an implementation of NUBS interpolator and presents the process of its integration into PC-NC. For more accurate feed, NURBS algorithm is improved. Also, Evaluation of real time NURBS interpolator is provided to verify fred accuracy and geometrical accuracy of NURBS curve. NURBS machining of fee surface is simulated on the real time NC simulator so that machining time is compared to that of linear path machining.

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다항식회귀곡선을 통한 임펠러의 역공학 적용에 관한 연구 (A Study on the Application of Reverse Engineering for Impeller using Polynomial Regression)

  • 황종대;정종윤;정윤교
    • 한국공작기계학회논문집
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    • 제13권5호
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    • pp.103-109
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    • 2004
  • This paper presents a fairing method for reverse engineering of a free-formed surface. Utilizing measured data points, reverse engineering is a useful method to construct a CAD model from physical model. Measured data points should be faired since raw data may have outliers. A fairing algorithm of polynomial regression model generates smooth curves of approximation in this paper. The faired curves are utilized to construct a free-formed surface. For a verifying example, an impeller blade is digitized with a CMM to collect raw data on the surfacce and a CAD model is constructed. This research produces impeller blades with 5-axis machining center through the CAD model and compares them with a physical model. As a result the produced surface modeled with the fairing method gives less error than that without the fairing.

The NURBS Human Body Modeling Using Local Knot Removal

  • Jo, Joon-Woo;Han, Sung-Soo
    • Fibers and Polymers
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    • 제6권4호
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    • pp.348-354
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    • 2005
  • These days consumers' various demands are accelerating research on apparel manufacturing system including automatic measurement, pattern generation, and clothing simulation. Accordingly, methods of reconstructing human body from point-clouds measured using a three dimensional scanning device are required for apparel CAD system to support these functions. In particular, we present in this study a human body reconstruction method focused on two issues, which are the decision of the number of control point for each sectional curve with error bound and the local knot removal for reducing the unusual concentration of control points. The approximation of sectional curves with error bounds as an approximation criterion leads all sectional curves to their own particular shapes apart from the number of control points. In addition, the application of the local knot removal to construction of human body sectional curves reduces the unusual concentration of control points effectively. The results may be used to produce an apparel CAD system as an automatic pattern generation system and a clothing simulation system through the low level control of NUBS or NURBS.

Insights into Structures in Policy-Driven Inter-Organisational Networks for Innovation: Cases from Malaysia's MSC Flagships

  • Omar, Aliza Akmar;Mohan, Avvari V.
    • Asian Journal of Innovation and Policy
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    • 제2권2호
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    • pp.240-264
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    • 2013
  • The study compares network structures that emerged in three inter-organisational projects set up under the MSC Malaysia initiative by the Government of Malaysia. These consortia are seen as policy-driven inter-organisational networks and, with data collected through interviews; the links among the organisations are mapped to gain an understanding of the structures that emerged in these networks. The findings provide lessons for other emerging countries that are embarking on similar projects i.e. cluster-oriented developments with policy-driven inter-organisational networks. These findings are seen as particularly useful when emerging countries invest in technology-related projects and invite multinational companies to work together with local firms.

수정 B-spline을 이용한 기능성 곡면의 Modeling (Modeling of Functional Surface using Modified B-spline)

  • 황종대;정종윤;정윤교
    • 한국정밀공학회지
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    • 제20권10호
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    • pp.156-163
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    • 2003
  • This research presents modeling of a functional surface which is a constructed free-formed surface. The modeling introduced in this paper adopts modified B-spline that is utilizing approximating technique. The modified B-Spline is constructed with altered control vertices. It is applied to measure points on a surface of an impeller blade. This research builds a surface-modeler accepting inputs of measured points. Generation of cutter-paths for NC machining employs the model of the constructed surfaces. The machined surfaces which is generated in several cases are compared in the aspect of machining accuracy.

How Firms Develop Linkages for Development and Growth - Cases in Malaysian Greenfield and Brownfield Technology Parks

  • Mohan, Avvari V.;Ismail, Isshamudin
    • World Technopolis Review
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    • 제4권2호
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    • pp.87-103
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    • 2015
  • This paper aims to explore how firms develop and grow in regional clusters based in a developing country. The argument is that start-ups / small and large firms are able to grow by developing linkages or networks for resources within clusters - and this tenet is based on studies of firms that are based from such clusters as Silicon Valley in the US, Cambridge in UK and other clusters from which have evolved over long periods of time. Most of the time we hear narratives from the developed world where there are brownfield cluster development efforts. In developing countries governments are making efforts to develop clusters from scratch - which in this paper we term as greenfield cluster versus a brownfield development, which is where the cluster is developed based on existing and new organisations in a region. In this paper, we believe the context of clusters can be important in determining the way firms develop linkages for their growth - and we look at two contexts in Malaysia ie. A greenfield cluster and a brownfield cluster. The paper presents findings from case studies of firms in a greenfield cluster (Cyberjaya) and a brown field cluster (Penang) in Malaysia. The cases reveal fairly different approaches to development of linkages or networks, which we hope will provides insights to cluster development officials and policy makers and implications to researchers for developing studies of clusters and innovation systems.

설계 초기 단계 형상정보 연동 데이터 호환체계 개발 - 오피스 매스를 중심으로 (Data interoperability between authoring software and BIM system focused on the office building in conceptual design phase)

  • 박정대
    • 한국산학기술학회논문지
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    • 제21권11호
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    • pp.494-500
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    • 2020
  • 디자인 대안들을 검토하는 설계 초기단계에서 복잡한 건축물 형상을 시각적으로 구현하기 위해서는 여러 모델링 기법이 요구된다. 형태를 정의해주는 기하학적 속성들을 포함한 형상정보를 서로 다른 디지털 플랫폼 사이에서 프로세스의 연속성을 유지한 채 변환하는 과정에는 상당한 기술적 제약이 존재하고 있다. 이에, 본 연구는 디자인 도구로서 3D 모델링 소프트웨어(McNeel Rhino 3D)와 BIM 시스템(Autodesk Revit Architecture)사이에서 데이터 변환을 위한 호환체계를 제시하고자 한다. 이를 위해, 중간 형식의 파일을 불러들이는 기존의 방식이 아니라, 곡면형상에 내재된 수학적 함수관계를 정의한 NUBS 속성을 지원해주는 파일 포맷(3DM)을 링크시키는 인터페이싱 방법론에 기반한다. 즉, 시각적 프로그래밍 도구인 다이나모(Autodesk Dynamo for Revit)를 이용하여 형상정보를 매스 패밀리와 연동시켜주는 알고리즘을 구현함으로써, 여러 계획안들의 형상으로부터 면적정보의 자동적인 산출이 가능하게 되어 초기 설계단계에서의 규모 검토에 적용 가능하다. 알고리즘 기반의 데이터 호환을 구현한 본 연구 성과는 정형과 비정형 형상의 오피스 건축물을 대상으로 실무에서 요구되는 작업환경 설정을 템플릿 형식의 가이드라인으로 제공하는 동시에, 설계 지원 도구로서 그 활용성이 기대된다.