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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 36, Issue 4 - Nov 1999
Volume 36, Issue 3 - Aug 1999
Volume 36, Issue 2 - May 1999
Volume 36, Issue 1 - Feb 1999
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On the Reduction of a Ship Resistance by Attaching an Air Cavity to Its Flat Bottom
Jin-Ho Jang ; Hyo-Chul Kim ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 2, 1999, Pages 1~8
Extensive resistance tests for a passenger boat(now in service at Chung-Ju lake) have been performed in a towing tank to investigate the effect of an artificial air cavity attached to the hull bottom on the reduction of the ship resistance. The attached air cavity has been observed at various air sully rates, from which we have determined a proper shape of an air supply device. In order to prevent the supplied air from leaking near the bilge of the ship, longitudinal barrier strips have been attached to both sides of the device. The investigation on their effectiveness reveals that a cascade system of the air supply device reduces the resistance of the ship furthermore. Energy saving of more than 10% is achieved at the design speed in spite of the additional power necessary for the air supply.
A Study on the Configuration of Two-Dimensional Waterjet Inlet
J.M. Lew ; S.K. Hong ; Y.G. Kim ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 2, 1999, Pages 9~21
The waterjet is very widely used today in propulsion system of high speed vessel but manufacturer is limited because of an efficiency and a difficulty of a manufacture on the inlet configuration of the waterjet. The importancy in designing the inlet configuration of the waterjet lies on the minimization of the cavitation which is largely affecting the efficiency. In this paper, the configuration analysis is carried out to find a optimum shape which is minimizing the cavitation using a two dimensional potential-based panel method with an inlet configuration of a flush type. Also, it is developed a direct design method finding an inlet configuration by a given pressure distributions. The numerically obtained optimum shape using this configuration analysis method show a good agreement compared to the Kashiwadani's results. It is carried out a direct design method over a lip and a ramp of an inlet configuration wish pressure distributions obtained a result of the configuration analysis and the results show a good agreement compared to original configuration.
A Research on the viscous flow and the hydrodynamic force due to the small-amplitude in-phase oscillation of multi-cylinders
Sung-Kyun Kim ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 2, 1999, Pages 22~28
Small amplitude in-phase oscillations of multi-cylinders are considered both numerically and experimentally. Flow field is separated into inner and outer regions. The basic unsteady solution is obtained analytically and the secondary flow, termed as steady streaming flow, can be obtained numerically by using Finite Volume Code with Panel Method. The Particle Induced Velocimetry, one of whole field measurements, is introduced for comparison with numerical flow visualization quantitatively. Among the algorithms for PIV, the Three Step Vector Searching Technique is applied to reduce CPU time. Small but non-zero damping coefficient, that is important in lightly damped system can be obtained with varying number of bodies and distances.
Simulation for Initial Motion of a Test Vehicle Launched from Sliding Launcher
Yepmg-Il Park ; Chan-Ki Kim ; Sun-Hong Kwon ; Man-Hyung Lee ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 2, 1999, Pages 29~39
In this study, mathematical modelling for initial motion of test vehicle launched from sliding launcher is performed, and simulation results from this mathematical models are verified by comparing them with sea trial results. Especially, it is showed that models using strip method give better results than using empirical formulae and linear equations of motion. This mathematical model can give useful tools to design sliding launchers or test vehicles.
A Study on the Level-Set Scheme for the Analysis of the Free Surface Flow by a Finite Volume Method
Il-Ryong Park ; Ho-Hwan Chun ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 2, 1999, Pages 40~49
A Finite Volume Method for the two-dimensional incompressible, two-fluids Navies-Stokes equation and level-set scheme are used to analyse the interface of two fluids, free-surface flow. The numerical characteristics and the applicability of level-set scheme are brief1y investigated and appraised by solving oscillating small surface wave in a water tank and dam break problems. In the numerical results, a method for improving the convergence of the solution is presented.
Computations of Dynamic Wave Loads of a Catamaran
H.H. Chun ; M.S. Kim ; J.H. Yang ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 2, 1999, Pages 50~60
In order to design a safe and economic catamaran, it is of clime importance to rigorously estimate the dynamic loads on the catamaran in waves. In this paper, the 2-D strip method by Lee et al. is. extended to a 3-D method which can estimate the dynamic loads(horizontal and vertical shear forses, and bending and torsional moments) acting on the center of the cross deck of the catamaran travelling in an arbitrary wave heading angle. The computational results are compared with Wahab et al's experimental data, and also 2-D and 3-D numerical results published. It is found that in general, the 3-D method give much improved correlations with the experimental data compared with 2-D methods, but there are some discrcrepancy between the same 3-D results used by the same theory. In order to improve the accuracy, the effect of the viscous flow and the rigid consideration of the forward speed effect seem to be necessary.
Active Control of a New Cargo Handling System Adapted for Time-Varying Tide
Hyoung-Seok Kim ; Dar-Do Chung ; Seung-Bok Choi ; Jae-Wook Lee ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 2, 1999, Pages 61~71
This paper resents a novel cargo system adapted for a sea port subjected to severe time-varying tide. The proposed system can perform loading or unloading by using a sort of hydraulic elevator associated with real-tim position control. As a preliminary phase, a small-sized model of the cargo system is designed and constructed. The model consists of three principal components ; container palette transfer(CPT) car, platform with lifting columns and cargo ship. The platform activated by the electro-rheological(ER) valve-cylinder is actively controlled to track the position of the cargo ship subjected to be varied due to the time-varying tide and wave motion. Following the derivation of the dynamic model for the platform and cargo ship motions, an appropriate control scheme incorporating time sequence and PID(proportional-integral-derivative) controller is formulated and implemented. Both the simulated and the measured control results are presented to demonstrate the effectiveness of the proposed cargo system.
A Study on the Prediction of the Maneuverability of Ships at Initial Design Stage, Considering Stern Form
Seung-Keon Lee ; Jae-Young Choi ; Yeong-Seok Seo ; Woo-Jin Lee ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 2, 1999, Pages 72~76
To predict the maneuverabiliy of a ship, it is most reliable to carry out the model tests for the ship. But, at the initial design stage of ships, scene other methods of predicting the overall maneuverabiliy of ships with confined data, like principal dimensions and propeller and rudder characteristics, are required. In this paper, the authors suggested new formulas for the linear derivatives of the sway force and yaw moment, based on the captive model test carried out by the Japanese researchers. These formulas can account the effects of stern frame line shape and stern profile, when assessing the maneuverability of ships. The usefulness of the formulas are discussed by comparing the simulations with the model tests.
A Study on the Collapse Strength Characteristics of Ship Bottom Plating Subject to Slamming Induced Impact Lateral Pressure Loads
Jeom-Kee Park ; Jang-Yang Chung ; Young-Min Paik ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 2, 1999, Pages 77~93
The twin aims of the paper are to investigate the collapse strength characteristics of ship plating subject to impact pressure loads and to develop a simple structural design formula considering impact load effects. The general purpose nonlinear finite element program STARDYNE together with existing experimental results is used to investigate the collapse behavior of plating under impact pressure loads. The rigid plastic theory taking into account large deflection effects is applied to the development of the design formulation. In the theoretical method, the collapse strength formulation for plating subject to hydrostatic pressure is first derived using the rigid plastic theory. By including the strain rate erects in the formulation it can be applied to impact pressure problems. As illustrative examples, the collapse behavior of steel unstiffened plates and aluminum alloy stiffened panels subject to impact pressure loads is analyzed.
A Study on the Geometric Nonlinear Behaviour of Ship Plate by Energy Method
Jae-Yong Ko ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 2, 1999, Pages 94~104
Plate buckling is very important design criteria when the ship is composed of high tensile steel plates. In general, the plate element contributes to inplane stiffness against the action of inplane load. If the inplane stiffness of the plating decreases due to buckling including the secondary buckling, the flexural rigidity of the cross section of a ship's hull also decreases. In these cases, the precise estimation of plate's behaviour after buckling is necessary, and geometric nonlinear behaviour of isolated plates is required for structural system analysis. In this connection, the author investigated the geometric nonlinear behaviour of simply supported rectangular plates under uniaxial compression in the longitudinal direction in which the principle of minimum potential energy method is employed. Based on the energy method, elastic large deflection analysis of isolated palate is performed and simple expression are derived to discuss the bifurcation paint type buckling and limit point type buckling.
Sensitivity Analysis of Coupled Horizontal and Torsional Vibration of Hull Girder
Dae-Seung Cho ; Sa-Soo Kim ; Doo-Yong Na ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 2, 1999, Pages 105~113
This paper resents a prediction method of natural frequencies of coupled horizontal and torsional vibration of hull girder based on design sensitivity analysis in case of the changes of system parameters. The sensitivity analysis is formulated applying the direct differentiation method and transfer matrix method. In the analysis, warping, shear deformation due to torsion and the continuity condition at the connected part of open and closed hull section are considered. Using the presented method. The affection for natural frequencies by the change of system parameters, especially cargo and added mass and their centers, is numerically investigated for a real large container carrier.
Development of Performance Evaluation Method of Shock-Resistance(DDAM) using NASTRAN DMAP
M.Y. Shin ; J.H. Lee ; J.H. Jung ; B.H. Kim ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 2, 1999, Pages 114~120
The DDAM(Dynamic Design Analysis Method) has been the most popular method for the shock response analysis of naval shipboard equipment. It was common to model the equipment as a simplified mass-spring system with multi degree of freedom in DDAM. Nowadays, however, it is necessary to adopt the finite element method for the shock response analysis due to the complexity of equipment. In this study, the DDAM program is developed to evaluate the performance of shock-resistance of FEM models using MSC/NASTRAN DMAP(Direct Matrix Abstraction Program) which provides the practical tools in interfacing with the externally developed program. Through the numerical test of the structural components and comparison with the results of ANSYS DDAM, it is confirmed that the developed program can be applicable to analyze the shock responses of the shipboard equipments.
Development of a Ship Calculation Program Based On the Geometric Model
Sang-Su Park ; Kyu-Yeul Lee ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 2, 1999, Pages 121~134
In this paper, a ship calculation program is developed, which prof[nuts hydrostatics and volume calculation intact and damage stability and hull variation. Hull form and compartment geometry are expressed with NURBS curve wire-frame model. Hydrostatics and volume calculation are performed directly with the intersection method between section geometry and 3D planar surface. Equilibrium ship position is calculated with hydrostatic equilibrium equation which is linearized by 1st order Taylor series expansion sequentially. The developed program shows more accurate results and easy uses than the latter.