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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 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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Computation of the Linear and Nonlinear Hydrodynamic Forces on Slender Ships with Zero Speed in Waves : Infinite-Depth Case
Yong-Hwan Kim ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 2, 2000, Pages 1~13
In the present paper, an infinite-depth unified theory is applied to the computation of the linear and second-order hydrodynamic forces on slender bodies. No forward speed is assumed, which is valid for some types of ships, like FPSOs and shuttle tankers. Strip theory solution, which is essential for the extension to theory is extended to unified theory, was obtained using NIIRD program developed at MIT. The linear theory is extended to the computation of the second-order mean-drift forces and moment. Furthermore, Aranha's formular is applied to the prediction of wave drift damping coefficients. From this study, it is proved that unified theory provides an accuracy comparable with 3D panel method for the second-order forces as well as the linear solution with much less computational effort.
Characteristics of Cavitation Noise of 2-D Hydrofoils
J.W. Ahn ; I.H. Song ; K.S. Kim ; K.Y. Kim ; I.S. Moon ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 2, 2000, Pages 14~21
The cavitation noise of 2-D hydrofoils is measured a cavitation tunnel. A new experimental method was developed for the noise measurement of 2-D hydrofoil. Three hydrofoils with the span of 600mm are designed and manufactured to investigate cavitation behavior and noise characteristics. The experimental results show the noise characteristics of various cavitation patterns and the noise performance of the three foils very well. This suggests that low-noise propeller blade section can be developed using the present experimental method.
Characteristics of Cavitation Noise on High-Speed Propellers
I.H. Song ; J.W. Ahn ; K.S. Kim ; I.S. Moon ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 2, 2000, Pages 22~29
The cavitation noised of high-speed propellers was experimentally studied in KRISO cavitation tunnel. In this paper, a series of cavitation noise tests were carried out for five propellers with various sections and loading distributions. From the experimental results, the noise characteristics of various cavitation pattern and the noise performance of the propellers were analyzed. There can be used for optimum design for high-speed propellers.
Roll Damping Moment of a Small Fishing Vessel by Free Rolling Test in Waves
H.H. Chun ; S.H. Chun ; S.Y. Kim ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 2, 2000, Pages 30~37
The roll damping characteristics of the three models of a 3ton class fishing vessel, that is the bare hull, hull with bilge keels, and hull with bilge keels and a central wing are investigated by the free roll tests in head waves in a towing tank with the variations of the forward speed, initial angle and OG. The wave length variations are also included. The experimental results are compared with the numerical results of mathematical modellings by the energy method for these three models and the energy dissipation patterns are also compared. The roll damping speed increases, the effect of the waves on the roll damping of the models with the additional devices is negligible due to the much increased damping caused by the lift increase.
On the Viscous Flow Around Breaking Waves Generated by a Submerged Cylinder(Part 3 : Survey of Flow Field Using PIV Technique)
B.S. Hyun ; Y.H. Shin ; K.S. Choi ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 2, 2000, Pages 38~45
A breaking-wave caused by a cylinder moving under the free-surface is studied, which is designed to unveil the interaction between breaker and cylinder using PIV at CWC. The detailed structures of the vortical flow is obtained from the velocity field measured by PIV technique. The vorticity distribution behind the breaker and originated from the breaker. It has been obvious that the vortices from breaker greatly affect the whole wake field at S/D=1. Certainly PIV was confirmed to be a very versatile means to investigate the complex flow fields such as breaking wave.
A Study on Course Stability of Towed Damaged-ship under Wind Pressure
K.H. Sohn ; Y.K. Kim ; S.G. Lee ; K.S. Choi ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 2, 2000, Pages 46~56
This paper is related with one of safety plans to rescue a damaged-ship whether by collision, grounding or internal accident. We discuss the problem on course stability of damaged-ship while towed under severe wind pressure. The characteristic equation to assess the stability on course, is derived from sway and yaw coupled motion of towing and towed vessels with wind effect. Through the numerical calculation on course stability of towing and towed vessels system, the relationship between the course stability of a towed damaged-ship and wind direction or towrope length, is clarified with the parameters of weather and damage conditions.
A B-Spline Higher Order Panel Method for Analysis of Three Dimensional Potential Flow
Gun-Do. Kim ; Ui-Sang Hwang ; Chang-Sup Lee ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 2, 2000, Pages 57~69
A higher order panel method based on representation for both the geometry and the velocity potential is developed for the analysis of steady flow around marine propellers. The self-influence functions due to the normal dipole and the source are desingularized through the quadratic transformation, and then the singular part is integrated analytically whereas the non-singular part is integrated using Gaussian quadrature. A null pressure jump Kutta condition at the trailing edge is found to be effective in stabilizing the solution process and in predicting the correct solution. Numerical experiments indicate that the present method is robust and predicts the pressure distribution around lifting bodies with much fewer panels than existing low order panel methods.
A Numerical Study on a Circulation Control Foil using Coanda Effect
J.J. Park ; S.H. Lee ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 2, 2000, Pages 70~76
A numerical study on the viscous flow around a 2-dimensional circulation control foil is carried out for application on the field of naval architecture and ocean engineering. The governing equations are the RANS and the continuity equations. The equations are discretized by finite difference method and MAC method and the pressure poisson equation is calculate by a SOR method and an O-type non-staggered boundary fitted coordinate system which is overlapped near the slot is used to improve the numerical accuracy. Turbulence is approximated by a modified Baldwin-Lomax turbulence model. In the present paper, the Coanda effect on a 2-dimensional foil of a 20% thickness ellipse with modified rounded trailing edge has been numerically studied. The change in drag and lift of the foil with various jet momentums are calculated and compared to the experimental results to show good agreements.
Approximation Method to Estimate Water Entry Impact Forces Acting on Light Weight Torpedo
Chan-Ki Kim ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 2, 2000, Pages 77~87
The water entry forces acting on an air-dropped torpedo are of the restrictions on launch speed and launch altitude, because it could cause the structural damage to components of torpedo. Therefore, it is necessary to estimate the water entry forces with confidence according to launch conditions. In this study, an approximation method for water entry forces is presented, and the results using this approximation are compared with those of other numerical methods. The magnitude and duration of impact forces estimated by the present approximation agree with those of impact by the analysis of ideal or viscous flow. This method can give useful tools to select the launch in initial design stage.
Experimental Study for the Optimum Rudder Design
Keh-Sik Min ; Kyung-Nam Chung ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 2, 2000, Pages 88~99
As a part of theoretical and experimental research works for the prediction and improvement of ship's maneuvering performance, an experimental study for the optimum rudder design has been carried out. Largely, this study is composed of the investigations on three major characteristics which determine rudder performance, that is, the investigations on section shape, planform and aspect ratio, and the investigation on the special section shapes. Some practically useful design directions and conclusion for each characteristic have been derived through this study. Among special section shapes, dolphin-tail type section shape has shown a possibility of significantly improving rudder performance if utilized as the section of rudders.
Comparative Studies on the Structural Design of Double Hull Tanker and Mid-deck Tanker
Seung-Soo Na ; Jae-Seon Yum ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 2, 2000, Pages 100~108
As U.S. congress and I.M.O. have recently adopted strengthened MARPOL73/78 regulations on marine pollution, it is necessary to develope a new type of tankers such as Double hull tanker(D/H Tanker) and Mid-deck tanker(M/D Tanker) and so on. Because most of researches are concentrated on the volume of oil spill due to collision of ships, in this paper, a structural design program for D/H Tankers and M/D Tankers is developed to suggest the effective type of tankers by comparing structural characteristics between their types. By this program, minimum hull weight designs of D/H tankers and M/D tankers considering tank arrangement are performed and the design results are compared each other. The efficient types of hull structure for the minimum weight design between D/H tankers and M/D tankers is proposed.
A Study on the Representation of Ship Hull Forms Using NURBS Surface - The Development of a Free Form Cutting Machine ; Part I -
H. Shin ; K.W. Park ; H.G. Park ; I.H. Kim ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 2, 2000, Pages 109~117
In order to develope ship hull forms. many various models are represented numerically in terms of B-spline surfaces and tested experimentally in the towing tank. It is very difficult to make various ship hulls with free forms in handiwork. As the first step of development of a free form cutting machine which becomes a good substitute for high-priced model cutting machines, free forms representation for model cutting are developed. In this paper, NURBUS surfaces are represented on the assumption that data points may be control points contrary to existing methods.
A Study on Rotary Bending Fatigue Strength of the
Gas Welded Joint in Air and Sea Water
S.W. Kang ; S.Y. Lee ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 2, 2000, Pages 118~126
TMCP steel has been widely used to construct ships and offshore structures. When it comes to ship and offshore structures, corrosion fatigue damages caused by sea water and fatigue occurred by wave-induced forces usually go on occurring simultaneously. So the fatigue life in corrosion environment is decreased markedly in comparison with that in air. The fatigue crack in corrosion easily initiates on welded joints of structure like as the fatigue crack in air. Therefore it is very important to study the fatigue properties of those of their welded joints as well as steel plates. In this study, rotary bending fatigue tests have been performed to investigate fatigue crack initiation and behavior of fatigue crack growth on CO2 gas weld HAZ of TMCP steel. The fatigue test used the specimens with various stress concentration factors in air and 3% NaCl solution
A Study on the Prediction and Control of Welding Deformations of Ship Hull Blocks
C.D. Jang ; C.H. Lee ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 2, 2000, Pages 127~136
Welding deformations reduce the accuracy of ship hull blocks and decrease the productivity due to correction work. Preparing an error-minimizing guide at the design stage will lead to a high quality as well as high productivity. And a precise method to predict the weld deformation is an essential part of it. This paper proposes an efficient method to predict complicated weld deformations based on the inherent strain theory combined with the finite element method. The inherent strain is determined by the highest temperature and the degree of restraint. In order to calculate the inherent strain exactly, it is considered that the degree of restraint becomes different according to the fabrication stages in real structures. A simulation of a stiffened plate shows the applicability of this method to simple ship hull blocks.