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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Society of Naval Architects of Korea
Journal Basic Information
Journal DOI :
The Society of Naval Architects of Korea
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Volume & Issues
Volume 37, Issue 4 - Nov 2000
Volume 37, Issue 3 - Aug 2000
Volume 37, Issue 2 - May 2000
Volume 37, Issue 1 - Feb 2000
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Analysis of the Nonlinear Wave-Making Problem of Practical Hull Forms Using Panel Method
Do-Hyun Kim ; Wu-Joan Kim ; Suak-Ho Van ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 4, 2000, Pages 1~10
A panel method based on the raised panel approach is developed for the nonlinear ship wave problem of practical hull forms. For the validation of the present numerical scheme. the developed method is first applied to Series 60 hull for which the extensive experimental data are available. As practical applications. the developed method is applied to KRISO 3600 TEU container ship and KRISO 300K VLCC. With the primary emphasis on the nonlinear effects of the global wave pattern generated by the two commercial ships. the calculated wave patterns are compared and verified with the experiments of KRISO. It is found that the calculated results of the present method are quite satisfactory compared with the linear methods like Dawson's approach and Neumann-Kelvin solution.
Hull Form Generation of Minimum Wave Resistance by a Nonlinear Optimization Method
Hee-Jung Kim ; Ho-Hwan Chun ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 4, 2000, Pages 11~18
This paper is concerned with the generation of an optimal forward hull form by a nonlinear programming method. A Rankine source panel method based on the inviscid and potential flow approximation is employed to calculate the wave-making resistance and SQP method is also used for the optimization. The hull form is represented by a spline function. The forward hull form of a minimum wave resistance with the given design constraints is generated. In addition, the forward hull form of a minimum total resistance by considering the frictional resistance together with an empirical form factor is produced and compared with the former result.
Development of Computational Methods for Viscous Flow around a Commercial Ship Using Finite-Volume Methods
Wu-Joan Kim ; Do-Hyun Kim ; Suak-Ho Van ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 4, 2000, Pages 19~30
A finite-volume method is developed to solve turbulent flows around modern commercial hull forms with bow and stern bulbs. The RANS equations are solved. The cell-centered finite-volume method employs QUICK and central difference scheme for convective and diffusive flux discretization, respectively. The SIMPLEC method is adopted for the velocity-pressure coupling. The developed numerical methods are applied to calculate turbulent flow around KRISO 3600TEU container ship. Surface meshes are generated into five blocks: bow and stern bulbs, overhang, fore and afterbody. 3-D field grid system with O-H topology is generated using elliptic grid generation method. Surface friction lines and wake distribution at propeller plane is compared with experiment. The calculated results show that the present method can be used to predict flow around a modern commercial hull forms with bulbs.
Application of Spectral Method to Laminar and Turbulent Flow Analysis around a Circular Cylinder
Y.S. Shin ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 4, 2000, Pages 31~39
In this study, the numerical analysis for laminar and turbulent flows around a circular cylinder is carried out from Reynolds number
, where the dramatic change of drag coefficients exists around Reynolds number
. The numerical results are compared with those of the experiments and they show reasonable agreements. The good results can be obtained without turbulent model by minimizing mesh size in the body normal direction and increasing mesh numbers in the body tangential direction. The future study for 2-dimensional flat plates with no pressure gradients and 3-dimensional bodies must be made to verify whether the same conclusions can be drawn.
Measurement of Cavitation Noise of a Hydrofoil and Prediction of Cavity Bubble Behavior
Jong-Woo Ahn ; Kwan-Hyoung Kang ; In-Haeng Song ; Kyung-Youl Kim ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 4, 2000, Pages 40~47
The cavitation noise of a hydrofoil is measured in a cavitation tunnel. It is exhibited that the noise level sharply increases with the inception of cavitation and increase with the decrease of the cavitation number until a moderate cavitation number. Below the cavitation number, the trend is reversed, which may be resulted from the interference effect between cavities. The trajectory of bubble is predicted by using the Lagrangian method. Meanwhile the size of the bubble is predicted based on the Kirkwood-Bethe approximation. The predicted results for the bubble size are compared with the experimental results. It is shown that the numerical method predicts the time history of cavities fairly well.
A Basic Research of Air Bubble Locus around the Ship Hull
H.E. Kim ; Y.G. Lee ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 4, 2000, Pages 48~55
A basic research of air bubble locus around the ship hull is performed to know the bubble's behavior which is generated around the hull surface. In this paper. bubble's behavior around the ship hull is calculated and experimented with the variation of bubble size and the location of bubble generation. For the use of the equation for bubble locus, Kawakita's equation which include the effect of bubble buoyancy is adopted. For the numerical simulation. a finite difference method based on the MAC method is used. Also experiments are performed about series 60 hull form at CWC. The results of calculation are compared with those of experiment.
An Experimental Study on the Characteristics of Current in the Ocean Engineering Basin
Chan-Kyu Yang ; Hark-Sun Choi ; Seok-Won Hong ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 4, 2000, Pages 56~65
This paper deals with the experimental study on the characteristics of current in the ocean engineering basin of KRISa, The unsteady characteristics of the flow is examined by analyzing time histories of streamwise velocity at some points. The major frequency of the fluctuating velocity was found by the spectral analysis of the measured data. The vertical and spanwise distributions of time averaged velocities were also examined. Especially, vertical distributions of the streamwise velocities with guide vanes are compared with those without guide vanes and it confirms the effeciency of the guide vane to improve the uniformity of the vertical profile of streamwise velocity. Finally, the measured data are regressed to give the relation between revolutions per minute(r.p.m.) and mean velocity.
Hydroelastic Analysis for a Very Large Floating Structure by Pressure Distribution Method
H.Y. Lee ; H. Shin ; H.S. Shin ; I.K. Park ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 4, 2000, Pages 66~74
In this paper, hydroelastic responses of the very large floating structure are studied based on the linear potential theory. A theoretical method is developed to analyze the hydroelastic reponses of very large floating structures(VLFS) using the pressure distribution method and the modal expansion method. The singularities distributed on a zero draft plate at the free surfaces and hydrodynamic pressures are evaluated. The deflections of structure are expanded approximately in terms of natural mode functions of free-free beam. The calculated items are pressure distributions. vertical motions, hydrodynamic coefficients and bending moments of VLFS. The numerical results are compared with those measured by experiments.
Motion of a Very Large Floating Structure in Irregular waves
H. Shin ; H.Y. Lee ; C.G. Lim ; H.S. Shin ; I.G. Park ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 4, 2000, Pages 75~81
Very large floating structures have rather small motion characteristics except their ends, where the motions become much larger due to the elastic motion of the structure. This paper presents the numerical predictions of hydroelastic behaviors of VLFS in irregular waves. To predict motion responses of structure in irregular waves, the source-dipole distribution method and finite element method is used.
Computation of Radar Cross Section of Ship's Structure using a Physical Optics Method
Sam-Wook Choi ; Sung-Youn Boo ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 4, 2000, Pages 82~91
In this study, a numerical scheme based on physical optics method is developed to predict RCS of perfectly conducting body. The scheme is verified through the comparisons of numerical values of cylinder and sphere with analytical ones. It is also applied to compute RCS of a fast naval craft. Major reflection of this ship at threat angle of 0 degrees is found to be due to superstructure and stern part of main hull. In order to investigate the shaping effects on the ship. inclination angles of the stern of main hull and superstructure are set to 12 degrees. The RCS of the ship with shaping is proven to be much reduced in comparison with one without shaping.
Strength Analysis of a Slender Doubler Plate of Ship Structure subjected to the Longitudinal In-plane Compression
Juh-Hyeok Ham ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 4, 2000, Pages 92~105
A study for the structural strength evaluation on the slender doubler plate has been performed through the systematic evaluation process. In order to estimate the proper static strength of doubler plate subjected to the longitudinal in-plane compression, elasto-plastic large deflection analysis is introduced including the contact effect between main plate and doubler. The characteristics of stiffness and strength variation are discussed based on their results. Also, in order to compare the doubler structure with the original strength of main plate without doubler, a simple formula for the evaluation of the equivalent flat plate thickness is derived based on the additional series analysis of flat plate structure. Using this derived equation, the thickness change of a equivalent flat plate is analyzed according to the variation of various design parameters of doubler plate and some design guides are suggested in order to maintain the original strength of main plate without doubler reinforcement. Finally, correlation between derived equivalent flat plate formula and the developed buckling strength formulas by author et al. is discovered and these relations are formulated for the future development of simple strength evaluation formula of doubler plate structure.