• Title/Summary/Keyword: Surface Normal Vector

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A Study on the Automatic Fairing and Modeling System of Hull From (선형의 자동순정 및 모델링 시스템에 관한 연구)

  • 김동준
    • Journal of Ocean Engineering and Technology
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    • v.14 no.2
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    • pp.121-127
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    • 2000
  • In this paper a new technique of inverse fairing problem for ship hull is proposed. Recently Lu solved the inverse fairing problem for automobile's body that was made by one surface element. In this system however hull surface is constructed by Gregory's composite surface interpolation method. So reflection line at boundary position is used as a tool of solving inverse problem in surface fairing. But the results are not good. The new concepts of Normal vector line and Constrained reflection line are introduced as an alternative tool. Energy minimization method for Normal Vector Line curve net and the inverse method for Constrained Reflection Line by using optimization technique are examined And the final lines from this proposed surface fairing method shows good fairness.

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Treatment of Contact between Roll/Roll and Roll/Strip for Rolling Process Simulation (압연공정해석을 위한 판과 롤의 접촉 경계면 처리)

  • 김태효;황상무
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.05a
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    • pp.156-159
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    • 2003
  • Surface normal vector and surface velocity are very important parameters to simulate rolling processes precisely. In this study, Local displacement functions are constructed for each node on the contact surface and parameters are found by the least square fitting of displacement on the neighbor nodes. Deformation gradient tensor is calculated from the displacement function and surface normal vector and velocity also can be derived. Flat rolling simulation model is presented on the basis of the suggested contact scheme. Series of rolling process simulation are carried out and the results are compared with the experiments.

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Multisensor System Integrating Optical Tactile and F/T Sensors for Determination of Type and Position of 3D Contact Surface (3차원 접촉면의 인식 및 위치의 결정의 위한 광촉각센서와 역각센서의 다중센서시스템)

  • 한헌수
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.2
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    • pp.10-19
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    • 1996
  • This paper presents a finger-shaped multisensor system which can measure the tyep and position of a target surface by contactl. The multi-sensor system consists of a sphere-shpaed optical tactile sensor located at the finger tip and a force/torque sensor located at the joint of a finger. The optial tactile sensor determines the type and position of the target surface using the shape and position of the CCD image of the touching area generated by a contact between the sensor and the taget surface. The force/torque sensor also determines the position and surface normal vector by applying the distributionof forces and torques t the contact point to the equations of finger shape. The measurements on the position and surface normal vector at a contact point obtined by two individual sensors are fused using a statistical method. The integrated sensor system has 0.8mm error in position measurement and 1.31$^{\circ}$ error in normal vector measurement. The developed sensor system has many applications, such as autonomous compliance control, automatic grasping and recognition, etc.

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Robust surface segmentation and edge feature lines extraction from fractured fragments of relics

  • Xu, Jiangyong;Zhou, Mingquan;Wu, Zhongke;Shui, Wuyang;Ali, Sajid
    • Journal of Computational Design and Engineering
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    • v.2 no.2
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    • pp.79-87
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    • 2015
  • Surface segmentation and edge feature lines extraction from fractured fragments of relics are essential steps for computer assisted restoration of fragmented relics. As these fragments were heavily eroded, it is a challenging work to segment surface and extract edge feature lines. This paper presents a novel method to segment surface and extract edge feature lines from triangular meshes of irregular fractured fragments. Firstly, a rough surface segmentation is accomplished by using a clustering algorithm based on the vertex normal vector. Secondly, in order to differentiate between original and fracture faces, a novel integral invariant is introduced to compute the surface roughness. Thirdly, an accurate surface segmentation is implemented by merging faces based on face normal vector and roughness. Finally, edge feature lines are extracted based on the surface segmentation. Some experiments are made and analyzed, and the results show that our method can achieve surface segmentation and edge extraction effectively.

A GEOMETRIC APPROACH TO TIMELIKE FLOWS IN TERMS OF ANHOLONOMIC COORDINATES

  • Yavuz, Ayse;Erdogdu, Melek
    • Honam Mathematical Journal
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    • v.44 no.2
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    • pp.259-270
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    • 2022
  • This paper is devoted to the geometry of vector fields and timelike flows in terms of anholonomic coordinates in three dimensional Lorentzian space. We discuss eight parameters which are related by three partial differential equations. Then, it is seen that the curl of tangent vector field does not include any component in the direction of principal normal vector field. This implies the existence of a surface which contains both s - lines and b - lines. Moreover, we examine a normal congruence of timelike surfaces containing the s - lines and b - lines. Considering the compatibility conditions, we obtain the Gauss-Mainardi-Codazzi equations for this normal congruence of timelike surfaces in the case of the abnormality of normal vector field is zero. Intrinsic geometric properties of these normal congruence of timelike surfaces are obtained. We have dealt with important results on these geometric properties.

Obtaining 3D Shape of Specular Surface Using Five Degrees of Freedom Camera System

  • Yusuf, Khairi;Miyake, Tetsuo
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 1998.06b
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    • pp.41-44
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    • 1998
  • In this paper, a new method of obtaining specular surface shape by using five degrees of freedom camera system is described. The normal vectors of the surface are extracted by achieving the coincident between the camera axis and the surface normal vector. This method uses a five degrees of freedom (5DOF) camera to fulfill this task. From the normal vector data, the shape of the surface is reconstructed. The result shows that the methodology improves the 3-D shape of object measurement with good accuracy.

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SUBMANIFOLDS WITH PARALLEL NORMAL MEAN CURVATURE VECTOR

  • Jitan, Lu
    • Bulletin of the Korean Mathematical Society
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    • v.35 no.3
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    • pp.547-557
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    • 1998
  • In this paper, we study submanifolds in the Euclidean space with parallel normal mean curvature vectorand special quadric representation. Especially we give a complete classification result relative to surfaces satisfying these conditions.

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PARAMETRIC EQUATIONS OF SPECIAL CURVES LYING ON A REGULAR SURFACE IN EUCLIDEAN 3-SPACE

  • El Haimi, Abderrazzak;Chahdi, Amina Ouazzani
    • Nonlinear Functional Analysis and Applications
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    • v.26 no.2
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    • pp.225-236
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    • 2021
  • In this paper, we determine position vector of a line of curvature of a regular surface which is relatively normal-slant helix, with respect to Darboux frame. Then, a vector differential equation is established by means Darboux formulas, in the case of the geodesic torsion is vanishes. In terms of solution, we determine the parametric representation of a line of curvature which is relatively normal-slant helix, with respect to standard frame in Euclidean 3-space. Thereafter, we apply this result to find the position vector of a line of curvature which is isophote curve.

Frictional Contact Model for Finite Element Analysis of Sheet-Metal Forming Processes (박판 성형 공정의 유한요소 해석을 위한 마찰접촉 모델)

  • 금영탁
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.9
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    • pp.2242-2251
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    • 1993
  • The mesh-based frictional contact model has been developed which does not rely on the spatial derivatives of the tool surface. Only points on the surface are evaluated from the description. which can then be simplified because of the relaxed demands placed on it. The surface tangents, normals, and corresponding derivatives at each finite-element node are evaluated directly from the finite-element mesh, in terms of the connecting nodal positions. The advantages accrue because there is no longer a need for a smooth tool surface to assure reasonable normals and derivatives. Furthermore, it can be shown that the equilibrium equations can only be properly written with a special normal derived from the mesh itself. The validity, accuracy, computation time, and stability of mesh-based contact model were discussed with the numerical examples of rounded flat-top and rough, flat-top rounded punch forming operations. Also, the forming process of a automobile inner panel section was simulated for testing the robustness of new contact model. In the discussion, the superiority of new model was examined, comparing with tool-based contact one.

Variational surface design under normal field guidance

  • Wu, Weidong;Yang, Xunnian
    • Journal of Computational Design and Engineering
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    • v.2 no.3
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    • pp.129-136
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    • 2015
  • This paper proposes a novel method for shape design of a Bezier surface with given boundary curves. The surface is defined as the minimizer of an extended membrane functional or an extended thin plate functional under the guidance of a specified normal field together with an initial prescribed surface. For given boundary curves and the guiding normal field, the free coefficients of a Bezier surface are obtained by solving a linear system. Unlike previous PDE based surface modeling techniques which construct surfaces just from boundaries, our proposed method can be used to generate smooth and fair surfaces that even follow a specified normal field. Several interesting examples are given to demonstrate the applications of the proposed method in geometric modeling.