• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.47-53
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• 2005

This paper presents the method for developing an optimum hull form with minimum wave resistance using SQP(sequential quadratic programming) as an optimization technique. The wave resistance is evaluated by a Rankine source panel method with non-linear free surface conditions and the ITTC 1957 friction line is used to predict the frictional resistance coefficient. The geometry of the hull surface is represented and modified using NURBS(Non-Uniform Rational B-Spline) surface patches. To verity the validity of the developed program the numerical calculations for Wigley hull and Series 60(C${_B}$=0.6) hull had been performed and the results obtained after the numerical calculations had been compared with the original hulls.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.8
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• pp.469-476
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• 2004

In this paper, a 3D shape optimization algorithm which guarantees a smooth optimal shape is presented using parameterized sensitivity analysis. The design surface is parameterized using Bezier spline and B-spline, and the control points of the spline are taken as the design variables. The parameterized sensitivity for the control points are found from that for nodal points. The design sensitivity and adjoint variable formulae are also derived for the 3D non-linear problems. Through an application to the shape optimization of 3D electromagnet to get a uniform magnetic field, the effectiveness of the proposed algorithm is shown.

• Journal of Navigation and Port Research
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• v.30 no.10 s.116
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• pp.869-875
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• 2006

This paper presents the method for developing an optimum hull form with minimum wave resistance using SQP(sequential quadratic programming) as an optimization technique. The wave resistance is evaluated by a Rankine source panel method with non-linear free surface conditions and the ITTC 1957 friction line is used to predict the frictional resistance coefficient. The geometry of the hull surface is represented and modified using NURBS(Non-Uniform Rational B-Spline) surface patches. To verity the validity of the developed program the numerical calculations for Wigley hull and Series 60( $C_B=0.6$) hull have been performed and the results obtained by the numerical calculations have been compared with the original hulls.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.301-308
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• 2005

In this study, we implement a framework that directly links a general tensor-based shell finite element to NURBS geometric modeling. Generally, in CAD system the surfaces are represented by B-splines or non-uniform rational B-spline(NURBS) blending functions and control points. Here, NURBS blending functions are composed by two parameters defined in local region. A general tensor-based shell element also has a two-parameter representation in the surfaces, and all the computations of geometric quantities can be performed in local surface patch. Naturally, B-spline surface or NURBS function could be directly linked to the shell analysis routine. In our study, we use NLib(NURBS libraray) to generate NURBS for shell finite analysis. The NURBS can be easily generated by interpolating or approximating given set of data points through NLib.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.2
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• pp.51-62
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• 1998

In this paper, a CAD/CAM system for 5-axis machining of model propeller is introduced. This system has been developed under the environment of personal computer and Windows NT. In order to enhance the productivity, existing text-based design S/W was integrated into this graphic-based system. Non-Uniform Rational B-Spline method is used to represent the sculptured surface of propeller blades and hub using point data, and surface blending between blade and hub is realized in this system. For 5-axis machining of sculptured surface, tool/work collision and interference are checked and inverse kinematic analysis is performed to make NC data. In addition, tool and workpiece are animated on the PC monitor by preparing NC verification module. Finally, optimal cutting conditions are determined empirically and those cutting conditions are integrated into this S/W so that the whole process from design to machining can be done automatically.

• Architectural research
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• v.16 no.2
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• pp.67-74
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• 2014

Free vibration analysis of thin shells is carried out by using isogeometric approach. For this purpose, a thin shell element based on Kirchhoff-Love shell theory is developed. Non-uniform rational B-spline surface (NURBS) definition is introduced to represent the geometry of shell and also used to derive all terms required in the isogeometric element formulation. Gauss integration rule is used for stiffness and mass matrices. The present shell element is then applied to examine vibrational behaviours of thin plate and shell structures. From numerical results, it is found be that reliable natural frequencies and associated mode shapes of thin shell structures can be predicted by the present isogeometric shell element.

• Architectural research
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• v.15 no.1
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• pp.35-42
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• 2013

A study on the free vibration and linear buckling analyses of thick plates is described in this article. In order to determine the natural frequencies and buckling loads of plates, a plate element is developed by using isogeometric approach. The Non-uniform B-spline surface (NURBS) is used to represent both plate geometry and the unknown displacement field of plate. All terms required in isogeometric formulation are consistently derived by NURBS definition. The capability of the present plate element is demonstrated by using several numerical examples. From numerical results, it is found to be that the present isogeometric element can predict accurate natural frequencies and buckling loads of plates.

• Architectural research
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• v.16 no.3
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• pp.121-129
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• 2014

A plate element is developed by using isogeometric approach in order to determine natural frequencies of laminated composite plates. Reissner-Mindlin (RM) assumptions is adopted to consider the shear deformation and rotatory inertia effect. All terms required in isogeometric element formulation are consistently derived by using Non-uniform rational B-spline surface (NURBS) definition. Gauss quadrature rule is used to form the element stiffness matrix and separately Lobatto quadrature rule is used to calculate element mass matrix. The capability of the present plate element is demonstrated by using numerical examples. From numerical tests, the present isogeometric element produces reliable numerical results for both thin and thick plate situations.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.2
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• pp.15-21
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• 1994

In the previous researches on mesh curve fairing method, a set of discrete data points in a mesh can be selected as variables. End tangent vectors can not be variables. This restriction makes some problems in preparing the end tangent vectors at the bow or stern parts, because their slopes are not infinites or zeros. In this paper end tangent vectors are included as variables and the more smooth results are obtained. Also two methods of constructing ship hull surface from mesh curves are examined. It is shown that the skinning method is better than non-uniform B-spline fitting method in representing the area near boundary. The generation of a ship surface is given as an example.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.181.5-181
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• 2001

This paper presents the method of 3D reconstruction of the depth information from the endoscopic stereo scopic images. After camera modeling to find camera parameters, we performed feature-point based stereo matching to find depth information. Acquired some depth information is finally 3D reconstructed using the NURBS(Non Uniform Rational B-Spline) algorithm. The final result image is helpful for the understanding of depth information visually.