• Journal of the Society of Naval Architects of Korea
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• v.28 no.1
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• pp.1-11
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• 1991

When a geometric modeling of a hull form for ship design and hull production is done, a hull fairing is a tedious process which wastes a lot of time, but it is unavoidable because hull consist of the sculptured surfaces. This paper presents the mathematical method of the direct fairing to overcome the tediousness of cross fairing. Bi-cubic B-spline surface description was adopted for the representation of the hull surface. The fairing process was executed by minimizing the strain energy in a shell plate. The color-encoded Gaussian curvature and strain energy were visualized on the screen to illustrate the fairness of the surface. The geometric information generated from the faired hull surface model was interfaced with the basic design calculation package and the hull production system.

• 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.

• Journal of Ocean Engineering and Technology
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• v.13 no.4 s.35
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• pp.169-173
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• 1999

In this paper some modifications for Lu's inverse method of fairing process are presented. The object function is changed and additional constraints for hull curve foiling is proposed. The newly introduced minimizing object function is the sum of the distances between the two curve's positions at the same parameter values instead of the sum of the distances between two vertices. The new one is better to represent the physical meaning of the object function, the smaller differences between two curves. In ship hull fairing the end tangent of curve has to be fined in some cases, so the additional constraint is considered to preserve the direction of end tangent. The sample results are shown.

• Bulletin of the Society of Naval Architects of Korea
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• v.19 no.4
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• pp.31-37
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• 1982

Developing a minimum wave resistance hull form which is satisfying the given requirements such as displacement and speed is one of the important problems in ship hydrodynamics. The theoretical approach conducted by Pien was successful in developing an optimized hull form, however, which can not be applied directly to practical hull form without manual lines fairing process. To avoid this difficulty, source distribution which arrived after the optimization was put into a fictitious restricted channel and as a result practicably modified hull form was derived by stream line tracing. The wave resistance of the hull thus obtained was calculated by solving the simplified integral equation suggested by Kan. The resistance at design point is almost same with that of the original hull which was represented by source distribution on the vertical rectangular center plane. It is therefore recommended to use the derived hull form for the hull which obtained after manual lines fairing process at Pienoid method. Further researches both in theory and experiment are necessary before this concept is put into practical application.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.32 no.1
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• pp.85-91
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• 1996

In the elM construction of naval architecture industry, ship hull surface modeling is critical process of design/manufacture process. This paper describes a fairing process of ship waterlines to represent boundary curves which are input data of surface modeling. Among the fairing methods, Sapidis's method and Rong's method are used in sequential to fair the boundary curves. Also it proposed four methods of determining the magnitude of end tangent vector. Among the four end tangents the best one is chosen by comparing with the shape of near curves. An application to the actual ship hull is given as an example.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.4
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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.

• Korean Journal of Computational Design and Engineering
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• v.13 no.6
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• pp.440-449
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• 2008

This paper deals with a method calculating various hull form parameters which are required in numerical analysis for ship performance such as motion, maneuverability, resistance and propulsion, etc. After the hull form is designed, before the model tests the ship's performances are evaluated by various analysis tools in which the hull form parameters are used with many kinds of forms aside from offset data. Here, The hull form parameters characterize the properties of hull form and contain positional, differential and integral information implicitly. Generally, the commercial CAD-system has not functions enough for supporting these form parameters and therefore each shipyard uses its own in-house analysis program as well as commercial analysis software. To overcome these limitations, modules for supporting these analysis programs have developed. The modules contain cubic composite spline cure using local curve fairing, intersect algorithm, Gaussian integral, and other geometric techniques needed in calculating hull form parameters. Using our analysis-supporting modules, a complex hull form can be remodeled exactly to the hull form designed by CAD-system and any hull form parameter required in various performance analyses can be calculated.

• 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.

• Journal of the Korean Institute of Navigation
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• v.23 no.1
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• pp.29-43
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• 1999

The production process of the compound-curved hull plates includes hull design, definition, fairing, modeling, lofting, cutting, and forming in sequence. Traditional fabrication methods and shop environment caused low level to productivity in medium and small sized shipyards. The most effective solution to solve those problems is to rationalize the layout of facilities. For the well-balanced development of domestic shipbuilding industry, it is urgently required to reduce the gap between modernized large sized shipyards and traditional small and medium sized shipyards in production technologies and efficiencies. For the efficient and accurate hull piece forming, all information from design to forming should be clarified and organized in a systematic manner. Thus, management of the information plays an important role in the computerized and automated of hull piece forming. The object of this paper is to survey the status of the field, to find out the feasibility and to introduce a draft of hull piece fabrication line for small and medium sized shipyards. The development of required system follows the object oriented technology to extend to simulation based system for carrying out physical product flow and facilities layout analysis. It is feasible to operate such a modernized facility for a group of small and medium shipyards who are unable to have each of their own facility because of its large amount of initial investment and insufficient work load.

• Journal of Ship and Ocean Technology
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• v.5 no.4
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• pp.1-18
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• 2001

Software written in academic environments is rarely integrated and/or reused. Moreover, typical academic software products do not communicate with commercial CAD packages, consequently functionality that is readily available to industry is not available do academic researchers. The Surface Design Library (SDL) is a library serving as a framework under which, CAGD software, intended for research or educational use, can be written in such a manner that it becomes a reusable part of a useful CAGD system. Moreover SDL is equipped with an IGES translator so that it communicates with commercial CAD packages, This paper gives a brief overview to SDL and presents examples of using it for high quality fairing performed on a naval ship hull, before employing commercial CAD packages for further design and analysis.