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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
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Journal DOI :
The Society of Naval Architects of Korea
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Volume & Issues
Volume 29, Issue 4 - Nov 1992
Volume 29, Issue 3 - Aug 1992
Volume 29, Issue 2 - May 1992
Volume 29, Issue 1 - Mar 1992
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Surface Creation using B-Spline Surface Method
Soo-Young Kim ; Il-Guk Woo ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 1~14
Using form parameters representing geometric characteristics of the form, this paper attempts the generation of 3-D free surface given in terms of B-spline surface equation. This is achieved by coupling the form parameter decision, Coons surface of the form parameters, and B-spline. To check the validing of the present method, a analogous surface to the bulbous bow was generated.
A Study on the Visualization of Ship Hull using Computer Graphics Techniques
H. Shin ; K.W. Park ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 15~20
This paper outlines the methods of visualizing 3-dimensional free form surfaces employing the Painter's algorithm, especially for the ship hull forms which are defined as open uniform Bi-cubic B-spline surfaces. The computer graphic codes are developed for the transparent wire-frame, the hidden surface removal and the shading visualization techniques, The codes are applied to the ship hull 3-dimensional surface visualization and the color graphic figures are displayed. Also Gaussian curvature is displayed on the color plots of the isoparametric net of the ship hull surface.
Numerical Analysis of Lifting Potential Flow around a Three-Dimensional Body moving beneath the Free Surface
B.K. Kim ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 21~32
Numerical solutions are presented for solving the free surface flow created by a three-dimensional body moving beneath the free surface with constant velocity at an angle of attack. The solution is obtained using a panel method based on the perturbation potential, which employs Havelock sources and normal dipoles distributed on the body surface and Havelock normal dipoles in the wake downstream of the trailing edge. A pressure Kutta condition with an iterative solution procedure is implemented to satisfy equal pressure condition on the upper and lower surfaces at the trailing edge. Numerical calculation examples in the present paper include an ellipsoid at zero angle of attack, a rectangular planform wing at a small angle of attack in the limit of zero Froude number and then free surface flows and hydrodynamic forces acting on the submerged spheroid and parabolic strut are calculated. Discussions are made about the validity of the present method.
Analysis of Sloshing Problem by Numerical Method
Y.H. Kim ; Y.J. Park ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 33~44
In the present paper, three types of analytic and numerical method are applied to the analysis of sloshing problem. Analytic solution with linear free-surface boundary condition is introduced and numerical methods are used to analyze flued flow trapped in two-and three-dimensional tanks. Source-distribution method is applied to two- and three-dimensional rectangular tanks and sphere tank. Finite difference method is utilized to compute fluid motion and pressure evolution in two dimensional tanks with girders or slopes. Calculated results are compared with those of experiment or other numerical techniques.
Mathematical Model for the Hydrodynamic Forces in Forward or Backward Low Speed Maneuvering
Jin-Ahn Kim ; Seung-Keon Lee ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 45~52
The Mathematical Model, which can describe the maneuvering motion of a ship in low speed, is highly required these days because it is directly related to the safety of ship in confused harbour. Kose has presented a new model for the low speed maneuvering motion, but the usefulness of it is not confirmed widely. Lets of difficulties are revealed in the case of low speed maneuver, The first is the fact that a ship moves the stirred water region for the longer time than in the case of high speed. So, the hydrodynamic forces, exerted on the hull need to be treated strictly, not by the ordinary differential equation with constant coefficients. Another difficulty is arised from the fact the lateral motion is relatively large comparing to the longitudinal motion in low speed. And, by the result the effect of cross-flow drag or vortex sheding effects are dominant. Besides, the captive model tests of low speed motion has lots of problems. For example, the hydrodynamic forces do not converge to a certain values for the long time. And the absolute values of measured forces are very small, so we must expend lots of efforts to raise up the S/N ratio of the experiments. In this paper, a new mathematical model for the maneuvering motion in low speed, is built up, and the usefulness is discussed, comparing with other models, for example, Kose's model or M.M.G. model or Cross-Flow model, The CMT data for a PCC model of 3.00 M length, released from the RR-742 of Japan, are used for the validation of each models.
A Study on the Memory Effect of the Radiation Forces in the Maneuvering Motion of a Ship
Seung-Keon Lee ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 53~58
The memory effect in maneuvering motion is very small and usually neglected. But, considering the maneuvering motion in waves, we need to calculate the memory effect strictly. Meanwhile. it is popular to treat the wave exciting forces as the steady sinusoidal forces and simply add to the right-hand side of the equation of the motion. This paper treats the memory effect in maneuvering motion when we take the wave exciting forces as the simple external forces and discuss the validity of such treatments.
A Finite Volume Method for Computations of Two-Dimensional Laminar Flows
Ki-Sup Kim ; Myung-Kyoon Chung ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 59~70
A Finite volume method for the computation of the two-dimensional, incompressible, steady, laminar Navier-Stokes equation is developed using a non-staggered grid system in a general curvilinear coordinate. The numerical pressure fluctuations, usually encountered when the non-staggered grid system is used, is suppressed by the momentum interpolation method. Flows around a NACA0012 foil section have been computed by the present method and the results show good agreements with other experimental and numerical ones.
Calculation of Wave-making Resistance using Neumann-Kelvin Theory
S.J. Kim ; S.J. Lee ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 71~79
In order to obtain the wave-making resistance of a ship, so-called the Neumann-Kelvin problem is solved numerically. For computing the Havelock source, which is the Green's function of the problem, we adopted the methods given by Newman(1987) for the term representing the local disturbance, and Baar and Price(1988) for the wave disturbance, respectively. In the numerical code we developed, the source strength is assumed as bilinear on each panel and continuous throughout the hull surface. The wave-making resistance is calculated using the algorithm of de Sendagorta and erases(1988), which makes use of the wave amplitude far downstream. The Wigley hull was chosen for the sample calculation, and our results showed a good agreement with other existing experimental and numerical results.
A Study on the Treatment of Open Boundary in the Two-Dimensional Free-Surface Wave Problems
Y.H. Kim ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 80~89
This paper deals with the open boundary problems, and two numerical schemes are used for the implementation of open boundary condition. One is to add the artificial damping term to dynamic free-surface boundary condition. Determination of suitable damping coefficient and the damping cone is the most important in this scheme. The other scheme is a modified Orlanski's method. This will be useful for the problems with unidirectional waves. A few typical free-surface wave problems are modeled for the numerical test. Method of solution is fundamental source-distribution method and the fully nonlinear boundary conditions are applied. The computed results are compared with those of others for the proof of practicality of these schemes.
Hydrodynamic Forces and Maneuvering Characteristics of Ships at Low Advance Speed
Kyoung-Ho Sohn ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 90~101
Some practical methods have already been proposed for predicting the characteristics of ship manoeuvring motions at relatively high advance speed. However, these methods can hardly be applied to motions of ships in starting, stoppint, backing and slow steaming conditions, even though such extensive motions are of vital importance from a safety point of view particularly in harbour areas. The method presented here aims at predicting the characteristics of ship manoeuvring at low advance speed, which covers starting, stopping, backing and slow steaming conditions. The force mathematical models at large angles of incidence to the hull as well as under the tilde range of propeller operations are formulated. Simulations of various manoeuvres at low advance speed are carried out for two types of merchant ship, i.e. a LNGC and a VLCC. Comparisons between simulations and corresponding full-scale measurements or free-running model tests provide a first verification of the proposed mathematical models.
A Comparison of Hydrodynamic Characteristics of Single and Tandem Strut SWATH Ships
Ho-Hwan Chun ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 102~116
This report is to provide a comparison of the hydrodynamic characteristics of a single strut SWATH(Small Waterplane Area Twin Hull) model and a tandem(twin) strut SWATH model. The hydrodynamic characteristics included are the resistance in calm water, 6 degree freedom of motion responses in stationary and with forward speeds, and wave loadings etc. All these quantities are measured in the towing tank and compared with the computational results. Based on the present study, the pros and cons for single and tandem strut SWATH designs are clarified and some design suggestions are made.
Detection of Sub-Breaking Waves around a Blunt Bow
Myung-Soo Shin ; Young-Gill Lee ; Eun-Chan Kim ; Seung-Il Yang ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 117~124
Waves around a practical hull form and a series 60 model are computed by rectangular variable spacing and staggered flesh systems based on MAC(Marker and Cell) method. As a governing equation, the Euler equation is adopted. The comparison indicates that the computed waves are in good agreement with the measured results and that the MAC method is useful. On the other hand, a critical condition for the appearance of sub-breaking waves derived from the in viscid instability analysis is applied to the calculated flow field around a blunt bow. It is confirmed that the derived condition detects well the appearance of sub-breaking waves.
Development of a Digital Motion Measuring System in a Real Seaway
Sa-Young Hong ; Jong-Sik Lee ; Seok-Won Hong ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 125~130
A digital 6-dof motion measuring system is developed using 7 accelerometers following Miles' method. A snoic wave height gauge is also developed to measure the relative wave height at the foremost end of the ship. By combining the time series of both 6-dof motions and relative wave height, we can estimate the time series of real sea wave. Results of model tests shows the validity of the developed system.
A Study on the Development of 2-Dimensional Numerical Wave Tank by the High-Order Spectral Method
Y.J. Kim ; J.H. Hwang ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 131~139
By introducing a body potential, the high-oder spectal method of Dommermuth and Yue(1987) is extended to treat the nonlinear interactions between the free surface and the submerged cylinder. A 2-dimensional numerical wave tank is developed based on this numerical scheme, and applied to the wave resistance problem and the wave maker problem. In the simulations, it is shown that the transient waves due to the impulsive start of the body motion make a practical obstacle to the acquisition of useful data from the numerical experiments. Gradual starting procedures are devised, and successful result of the quasi-steady state or the uniform regular wave group was obtained. Within the author's present knowledge, the present numerical scheme is one of the most efficient numerical schemes which can treat the nonlinear interactions between the free surface and the body motion in time-domain.
Vibration Analysis of Symmetrically Laminated Composite Rectangular Plates
T.Y. Chung ; J.H. Chung ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 140~148
The free vibration problem of symmetrically laminated composite rectangular plates is formulated based on anisotropic thick plate theory including the effects of shear deformation and rotary inertia. Considering the difficulty of obtaining closed-form solutions, Rayleigh-Ritz analysis using polynomials having the property of Timoshenko beam functions as trial functions is adopted. The boundary conditions elastically restrained against rotation are accomodated as well as classical boundary conditions. From the results of numerical studies, the validity of the present method is verified. And it is also found that the adoption of thick plate theory for the vibration analysis of laminated composite plates is essential because of the relatively large shear deformation effect, and that the convergence of the Rayleigh quotient to the stationary value is less rapid in anisotropic composite plates than that in the orthotropic ones due to more complicated mode shapes of the former.
Development of Automatic Data Generation Program for Finite Element Structural Analysis of Oil Tankers
S.W. Park ; J.G. Shin ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 149~156
An efficient preprocessor is developed for the finite element structural analysis of a ship's hull module. A hull module structure is divided into three groups for easy data handling : longitudinal members, transverse members, and transverse bulkheads. Based on the classification rules and design practices at shipyards, the preprocessor can create finite element nodes, elements, boundary conditions, and loadings automatically. By connecting the preprocessor with the ANSYS program, we can obtain the results of ship structureal analysis more efficiently. Applied to a typical double-hull oil tanker, the present preprocessor shows various advantages over conventional general-purpose preprocessors.
Study on the Theoretical Background of the Rules for the Bulkhead Plates
J.S. Mah ;
Journal of the Society of Naval Architects of Korea, volume 29, issue 3, 1992, Pages 157~165
Three dimensional structural analysis is carried out to evaluate the global behavior of the platings for the watertight bulkhead and deep tank bulkhead of the selected model ship and to analyze the theoretical background of their formulations for the bulkhead platings in the Rules of each classification societies. In this study, coarse and fine mesh analysis for transverse bulkhead is carried out to know the stress distribution in way of the concerned areas and that result is presented to show the back data for the new formulations of such transverse bulkhead platings.