• Journal of the Society of Naval Architects of Korea
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• v.42 no.4 s.142
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• pp.315-321
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• 2005

The effect of water depth on the wave making resistance performance is great where Froude number based on the water depth is close to one. The increase of wave making resistance due to the shallow water effect is evaluated by a numerical analysis in the present study. Three-dimensional Navier-Stokes and continuity equations are employed for the present study and the equations are discretized by finite difference method. The interface between water and air is determined by the level set method. In order to validate the numerical method, the change of resistance performance for Wigley hull according to the water depth is evaluated and the computed resistance coefficient is compared with measured one. The present numerical method is applied for the simulation of wave phenomena around a Ro-Pax hull form and the computed results are discussed in the resistance performance point of view.

• Journal of Ocean Engineering and Technology
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• v.29 no.3
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• pp.224-230
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• 2015

Vessels are traditionally optimized for a single condition, normally the contract speed at the design draft. The actual operating conditions quite often differ significantly. At other speed and draft combinations, adjusting the trim can often be used to reduce the hull resistance. Changing the trim is easily done by shifting ballast water. There are several ways to assess the effect of the trim on the hull resistance and fuel consumption, including in-service measurements, model tests, and CFD. In this paper, CFD is employed for the assessment of the resistance performance according to the trim conditions. The commercial CFD code of the STAR-CCM+ is utilized to evaluate the ship’s resistance performance on a 6,800 TEU container ship. To validate of the effectiveness of STAR-CCM+, the experimental result of the KCS hull form is compared with the result from STAR-CCM+. It is found that the total resistance of the 6,8000 TEU container ship was reduced by 2.6% in the case of a 1-m trim by head at 18knots.

• Special Issue of the Society of Naval Architects of Korea
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• 2017.10a
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• pp.59-62
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• 2017

Recently oil price has got lower, but energy efficiency has been considered as an important factor to minimize ship operational costs and reduce greenhouse gas emissions. For the reason, it is necessary that energy efficiency improvement for hull form design and operational performance reflect an understanding of the vessel's operational profile. Throughout the life of the vessel, this can lead to important economies of fuel, even if, in some cases, a small penalty can be taken for design condition. In the present paper, hull form was developed for 5,000TEU class container carrier at given operation profile. As a CFD result at several design point, optimized hull form has improved resistance performance in comparison with the basis hull form. To reducing the viscosity and the wave resistance at multi draft and multi speed, the hull form was investigated for Cp-curve, frame and local shape. Numerical study has been performed using WAVIS & Star-CCM+ and verified by model test in the towing tank.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.6
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• pp.763-769
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• 2010

Thanks to the rapid advancement of computational power and development of numerical methods, Computational fluid dynamics techniques are being used widely for the prediction of ship resistance performance. In the present study, an automatic tool was developed to facilitate hull form modification, consequent mesh generation, and flow analysis for parametric study. It is a tedious job to go back and forth between geometry modification and mesh generation for every hull form variation. With the developed tool, users can make multiple hull form variation and their hull form performance prediction easily in a few simple steps. The verification of the developed tool was done by applying it to resistance performance parametric study of a generic POD propulsion cruise ship with different lengths of bow and stern. It is believed that the tool can be extended to more sophisticated hull form variation and help optimize the ship performance more efficiently.

• Journal of the Society of Naval Architects of Korea
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• v.28 no.2
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• pp.28-39
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• 1991

A study on the optimization problems to find forebode shapes with minimum wavemaking and frictional resistance was performed. The afterbody was fixed as a given hull and only forebode offsets were treated as design variables. Design variables were divided into the offsets of given hull and small variation from them. For the wavemaking resistance calculation, Neumann-Kelvin theory was applied to the given hull and thin ship theory was applied to the small variation. ITTC 1957 model-ship correlation line was used for the calculation of frictional resistance. Hull surface was represented mathmatically using shape function. As object function, such as wavemaking and frictional rersistance, was quadratic form of offsets and constraints linear, quadratic programing problem could be constructed. The complementary pivot method was used to find the soulution of the quadratic programing problem. Calculations were perfomed for the Series 60 $C_{B}$=0.6. at Fn=0.289. A realistic hull form could be obtained by using proper constraints. From the results of calculation for the Series 60 $C_{B}$=0.6, it was concluded that present method gave optimal shape of bulbous bow showing a slight improvement in the wave resistance performance at design speed Fn=0.289 compared with the results from the ship theory only.

• Composites Research
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• v.34 no.6
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• pp.350-356
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• 2021

When a ship with a planing line operates or turns in a straight line, the floating position and trim change according to the speed, and a large resistance is generated on the hull. In this paper, the resistance to a planing line was estimated through the computational fluid dynamics of a leisure boat with improved hull weight and durability by applying a carbon composite material to the hull. The resistance performance of the bow and stern of the 18ft class leisure boat was checked and the flow field of the entire vessel was estimated, and the stability of the planing line was confirmed by comparing the resistance of each trim through numerical analysis. In addition, it was confirmed that the designed planing line could withstand it sufficiently because the force applied to the hull was not large, and The stability of the boat was analyzed by calculating the wavelength of the wave and the length of the ship as the ratio of gravity to the inertial force and checking how much force the rolling occurred.

• Journal of the Korean Institute of Navigation
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• v.12 no.3
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• pp.23-37
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• 1988

This paper deals with the method of determining the drag of hull surface which has any quality of roughness. The method consists mainly of the theoretical point of view, then the theory enables the drag coefficient to be calculated at full scale. The hydrodynamical roughness function of hull surface ${\triangle}U_+$, affected by the hull roughness are considered as to two cases, smooth surface and rough surface case separately. The inadequacy of a single parameter to define hull roughness is discussed and thus an as additional texture parameter is proposed.

• Journal of Ship and Ocean Technology
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• v.11 no.4
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• pp.55-71
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• 2007

The primary objective of this work is to develop methodologies for virtual model basin and to demonstrate the capabilities for generic multi-hull ship geometry. A computational fluid dynamics approach is used to simulate various model basin tests for steady resistance, maneuvering and seakeeping. For a catamaran hull configuration, the methodologies are used for solving these problems and the results are discussed. Computational results are compared with the results of a benchmarked potential flow theory method for calm water resistance.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.4
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• pp.32-47
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• 1996

Systematic theoretical arm experimental studies have been performed to establish the methods of the hull form design, the optimum dimension selection and the resistance estimation for the displacement type super high-speed ships. In this study, theoretical hull form design method of the displacement type super high-speed ships has been developed first by the minimum resistance theory and the sectionally-varying hull form equation. Utilizing the established hull form design method, sixty(60) series hull forms have been prepared according to the systematic variations of the important design variables, and model tests were conducted for the sixty(60) series ship models. Finally, regression analyses have been performed for the results of model tests. It is considered that this is the first systematic and multi-purpose study in the world for the super high-speed ships. The study has been completed very successfully. The prepared computer program is now being actively utilized as an efficient tool for the design of the displacement type super high-speed ships.

• Journal of Ocean Engineering and Technology
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• v.33 no.4
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• pp.313-321
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• 2019

The prediction of the hydrodynamic performance of a planing hull vessel is an important and challenging topic for computational fluid dynamic (CFD) applications to naval hydrodynamics. In this paper, the resistance and planing attitude analysis for a Fridsma hull, which is a prismatic planing hull, in still water are numerically studied using OpenFOAM. OpenFOAM is an open source code package based on C++ libraries and the finite volume method (FVM) for the discretization of the RANS equation. The volume of fluid method (VOF) is used to capture the water-air interface and the SST ${\kappa}-{\omega}$ model is used for the turbulence simulation. The overset mesh method is used to capture the large motion of the hull at higher speeds. Before the extensive analysis, uncertainty analyses using various time steps and grid sizes were performed for one ship speed case of Fn = 1.19. The results of the present study are compared with those of a model test, other CFD research, and Savitsky's empirical formula. The results of the present study, following the trend of other CFD results, slightly over predict the resistance and under predict the sinkage and, more significantly, the trim.