• Title, Summary, Keyword: NURBS

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Investigation on the Description Method of Extrusion Die Surface using NURBS Surface and Area Mapping Method (NURBS 곡면과 면적 사상법을 이용한 압출 금형곡면의 표현 방법에 관한 연구)

  • 유동진;권혁홍;임종훈
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.343-346
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    • 2003
  • In order to construct the extrusion die surface of arbitrarily shaped sections, an automatic surface construction method based on NURBS surface and area mapping method is proposed in the present work. In the present study, a center point for area mapping is determined by introducing the marring concept based on constant area proportionality between original billet and final product. The characteristic points of inlet profile is determined using the traditional area mapping method and the root finding numerical method. The inlet and outlet profiles are precisely described with NURBS curves using the characteristic points of entry and exit sections. For the construction of NURBS surface, an interpolation method for the pre-determined two section curves has been developed to be used in the generation of interior control points and weights. To show the validity of the proposed method, automatic die surface generation is carried out for the several kinds of shaped sections.

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Variation of the Hull Form using SAC and NURBS Curve (횡단면적 곡선과 NURBS곡선을 이용한 선형 변환)

  • Kim, Hyun-Cheol;Kim, Soo-Young;Ahn, Dang;Ha, Mun-Keun
    • Journal of the Society of Naval Architects of Korea
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    • v.32 no.3
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    • pp.29-36
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    • 1995
  • This paper presents a variation method of the parent ship using sectional area curve & the definition of NURBS curve. That is, global variation of the hull form is made systematically by the geometrical property of sectional area curve, and Local variation of the hull form is executed by the definition of NURBS curve. Then the designer may determine New hull form considering New section area curve, design condition, etc.

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Integrated NURBS Surface Interpolator Considering Both Rough and Finish Cuts (황삭 및 정삭을 고려한 통합형 NURBS 곡면 인터폴레이터)

  • Koo, Tae-Hoon;Jee, Sung-Chul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.11
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    • pp.1958-1966
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    • 2003
  • Three-axis CNC surface machining entails a series of processes including rough cutting, intermediate cutting and finish cutting for a reference surface defined in CAD/CAM. This study is targeting development of an integrated NURBS surface interpolator that can incorporate rough, intermediate and finish cutting processes. In each process, volume to be removed and cutting condition are different according to the shape of a part to be machined and the reference surface. Accordingly, the proposed NURBS surface interpolator controls motion in real-time optimized for the machining conditions of each process. In this paper, a newly defined set of G-codes is proposed such that NURBS surface machining through CNC is feasible with minimal information on the surface composition. To verify the usefulness of the proposed interpolator, through computer simulations on NURBS surface machining, total machining time, size of required NC data and cutting force variations are compared with the existing method.

Quadrilateral Mesh Generation on Trimmed NURBS Surfaces

  • Chae, Soo-Won;Kwon, Ki-Youn
    • Journal of Mechanical Science and Technology
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    • v.15 no.5
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    • pp.592-601
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    • 2001
  • An automatic mesh generation scheme with unstructured quadrilateral elements on trimmed NURBS surfaces has been developed. In this paper NURBS surface geometries in the IGES format have been employed to represent geometric models. For unstructured mesh generation with quadrilateral elements, a domain decomposition algorithm employing loop operators has been modified. As for the surface meshing, an indirect 2D approach is proposed in which both quasi-expanded planes and projection planes are employed. Sampled meshes for complex models are presented to demonstrate the robustness of the algorithm.

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A Study of Hull Form Generation for Chine Type of Fishing Vessel Using NURBS Method (NURBS 기법을 이용한 Chine Type 어선의 선형생성에 관한 연구)

  • 박제웅;조민철
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.40-44
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    • 2001
  • 선형개발에 대한 연구는 주로 대형선박을 기준으로 Bezier, B-spline 그리고 NURBS와 같은 합성곡선생성기법을 이용하여 일반 곡선기법으로는 표현하기 힘든 구상선수나 굴곡이 심한 선미 등을 표현하고 검증하는 것으로 이루어지고 있다. 하지만, 전체 선박의 70%를 차지하고 있는 중소형 어선의 선형에 대한 연구나 기술적인 보고는 상대적으로 미흡한 실정이다. 본 연구에서는 기존의 라운드타입에서 챠인 및 신챠인타입으로 변화해 가는 중소형 어선의 선형을 NURBS기법을 이용하여 표현하고, 전산화하는 프로그램을 개발하였다.

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Numerical Representation of the Hull Form using NURBS Curve (NURBS 곡선을 이용한 선형의 수치적 표현)

  • Hyun-Cheol Kim;Soo-Young Kim
    • Journal of the Society of Naval Architects of Korea
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    • v.32 no.1
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    • pp.1-8
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    • 1995
  • This paper presents possibilities of a numerical hull form representation in the form of curve designs, which require a variety of form variations. The numerical representation method of the hull form is developed using NURBS curve with sufficient continuity and local variation.

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A New Method of the Global Interpolation in NURBS Surface (NURBS Surface Global Interpolation에 대한 한 방법)

  • 정형배;나승수;박종환
    • Korean Journal of Computational Design and Engineering
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    • v.2 no.4
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    • pp.237-243
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    • 1997
  • A new method is introduced for the interpolation in NURBS Surface. This method uses the basis functions to assign the parameter values to the arbitrary set of geometric data and uses the iteration method to compute the control net. The advantages of this method are the feasible transformation of the data set to the matrix form and the effective surface generation as a result, especially to the design engineer.

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Functionality Analysis of NURBS Modeling Tools (NURBS 모델링 도구들의 기능분석)

  • Park, K.R.;Choi, J.J.;Chang, D.H.
    • Electronics and Telecommunications Trends
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    • v.14 no.3
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    • pp.19-30
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    • 1999
  • 컴퓨터 그래픽스를 이용하여 3차원 물체를 모델링하는 방법은 그 이론적 배경에서 크게 두 가지로 나뉘는데, 직선들과 삼각형 혹은 사각형들을 연결하는 폴리곤 모델링 방법과 NURBS(Non Uniform Ra-tional B-splines)라는 수학적으로 정의된 곡선 혹은 곡면을 이용하는 방법이 있다. 본 고는 이미 상용화되어 사용되고 있는 몇 가지 3차원 모델링 소프트웨어들의 기능 중에서 NURBS 모델링 기능을 살펴보고 이를 비교.분석해 본다.

THE ISOGEOMETRIC VARIATIONAL MULTISCALE METHOD FOR LAMINAR INCOMPRESSIBLE FLOW

  • Moulage, Yourself Gaffers;Ahn, Hyung-Taek
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.16 no.1
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    • pp.65-84
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    • 2012
  • We present an application of the variational multiscale methodology to the computation of concentric annular pipe flow. Isogeometric analysis is utilized for higher order approximation of the solution using Non-Uniform Rational B-Splines (NURBS) functions. The ability of NURBS to exactly represent curved geometries makes NURBS-based isogeometric analysis attractive for the application to the flow through the curved channel.

Real-time Line Interpolation of a NURBS Curve based on the Acceleration and Deceleration of a Servo Motor (서보 모터의 가감속을 고려한 NURBS 곡선의 실시간 직선 보간)

  • 이제필;이철수
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.405-410
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    • 2001
  • In this paper, a new parametric curve interpolator is proposed based on a 3D(3-dimensional) NURBS curve. A free curve is generally divided into small linear segments or circular arcs in CNC machining. The method has caused to a command error, the limitation of machining speed, and the irregular machining surface. The proposed real-time 3D NURBS interpolator continuously generates a linear segment within the range of allowable acceleration/deceleration in the motion controller. Therefore, the algorithm calculates the curvature and the remained distance of a command curve for the smoothing machining. It is expected to attaining high speed and high precision machining in CNC Machine Tool.

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