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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
Selecting the target year
Roll Damping Moment of a Small Fishing Vessel by Free Rolling Test in Calm Water
H.H. Chun ; S.H. Chun ; S.Y. Kim ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 1, 2000, Pages 1~9
The roll damping characteristics of the three models of a 3 ton class fishing vessel such as the bare hull, hull with bilge keels, and hull with bilge keels and a central wing are investigated by the free roll tests in calm water in a towing tank with the variations of the forward speed, initial angle and OG. 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.
Effect of Reynolds Number, Leading Edge Roughness and Air Content on the Cavitation Performance of Model Propellers
Ki-Sup Kim ; Kyung-Yeul Kim ; Jong-Woo Ahn ; Jin-Tae Lee ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 1, 2000, Pages 10~25
The effects of Reynolds number of model propeller leading edge roughness and air content resolved in tunnel water on cavitation inception, cavitation extent and pressure fluctuation were investigated experimentally by using two model propellers in a cavitation tunnel. Cavitation observation and propeller induced fluctuating pressure measured in the present model test were compared with the model test results of other research institutes and the full-scale data of a German container ship(Sydney Express). The comparison shows a reasonable agreement.
Experiment Correlation Analysis of Popeller Open-water Characteristics at Towing Tank and Caviaion Tunnel
K.S. Kim ; K.Y. Kim ; J.W. Ahn ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 1, 2000, Pages 26~39
This paper presents the influence of Reynolds number on propeller open-water performance at the towing tank and the cavitation tunnel for series propellers(No. of blade=4,
). It is shown that the Reynolds number recommanded by 15th and 17th ITTC is not large enough to obtain reliable P.O.W. test results and then the suitable test conditions for the both facilities is suggested. The correlation of the propeller open-water characteristics at the cavitation tunnel and the towing tank is described and a correlation factor
is deduced from those test results. The viscous effect of the flow around the propeller shaft on the propeller characteristics is investigated from the velocity measurement by Laser Doppler Velocitimetry(L.D.V.). The measured velocity distribution shows that viscous flow effect is not negligible.
A New Empirical Formula for Steering Gear Torque of Tankers by Statistical Analysis based on Sea Trial Data and Modified Lifting Line Theory
D.I. Son ; K.P. Rhee ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 1, 2000, Pages 40~49
In this paper, an empirical formula to estimate the steering gear torque of a Tanker with a horn type rudder was developed by using the statistical analysis. The hydrodynamic characteristics of the horn type rudder in the free-stream condition were calculated by using the modified lifting line theory by Molland, and the interaction effects by propeller and hull were analyzed by the regression analysis of the sea-trial data of 32 vessels. The comparison with the delivered vessels' data shows that the formula can be used for predicting the steering gear torque at the initial design stage.
Dynamic Stability of a Damaged Ship in Beam Wind and Waves
K.H. Sohn ; S.G. Lee ; K.S. Choi ; Y.S. Kim ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 1, 2000, Pages 50~59
This paper presents a brief outline of dynamic stability of a damaged ship at final stage of flooding in rough beam wind and waves. One degree-of-freedom, roll equation is adopted with effects of flooding water and external forces due to wind and waves, but without effect of sloshing. We discuss the dynamic stability of the damaged ship in terms of capsizing probability based on risk analysis, the method of which was firstly proposed by Umeda et al. to high speed craft in intact condition. As a result, we can evaluate the dynamic stability of the damaged ship in probabilistic manner according to sea state, operating condition and damage situation.
Influence of the Leading Edge Shape of a 2-Dimensional hydrofoil on Cavitation Characteristics
I.H. Song ; J.W. Ahn ; I.S. Moon ; K.S. Kim ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 1, 2000, Pages 60~66
In order to improve cavitation characteristics for a high-speed propeller, leading edge shape of a 2-D hydrofoil is investigated numerically and experimentally. For flowfield analysis around the leading edge, the incompressible Reynolds Averaged Navier-Stokes(RANS) equation is solved using the standard
turbulence model and a finite volume method(FVM). The cavitation thickness, which is occurred on hydrofoil surface, is predicted using the panel code. It is shown that the calculation codes predict the experimental trend fairly well. From these results, new hydrofoils are designed
Numerical Analysis of Two-Dimensional Nonlinear Radiation Problem Using Higher-Order Boundary Element Method
Hong-G. Sung ; Hang-S. Choi ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 1, 2000, Pages 67~81
An accurate and efficient numerical method for two-dimensional nonlinear radiation problem has been developed. The wave motion due to a moving body is described by the assumption of ideal fluid flow, and the governing Laplace equation can be effectively solved by the higher-order boundary element method with the help of the GMRES (Generalized Minimal RESidual) algorithm. The intersection or corner problem is resolved by utilizing the so-called discontinuous elements. The implicit trapezoidal rule is used in updating solutions at new time steps by considering stability and accuracy. Traveling waves caused by the oscillating body are absorbed downstream by the damping zone technique. It is demonstrated that the present method for time marching and radiation condition works efficiently for nonlinear radiation problem. To avoid the numerical instability enhanced by the local gathering of grid points, the regriding technique is employed so that all the grids on the free surface may be distributed with an equal distance. This makes it possible to reduce time interval and improve numerical stability. Special attention is paid to the local flow around the body during time integration. The nonlinear radiation force is calculated by the "acceleration potential technique". Present results show good agreement with other numerical computations and experiments.
On the Viscous Flow Around Breaking Waves Generated by a Submerged Cylinder(Part 1 : Wave Pattern and Surface Pressure)
B.S. Hyun ; Y.H. Shin ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 1, 2000, Pages 82~90
An experimental study has been carried out at circulating water channel to investigate the non-breaking and breaking waves generated by a submerged circular cylinder steadily moving under the free surface. Free surface profiles and pressure distributions on cylinder surface were measured at various submerged depths of cylinder. They were complemented by the measurements of velocities, head losses and turbulence intensities in the wakes of body and "breaker". Part 1 of this three-part paper describes the experimental arrangement and the patterns of wave profile and pressure distribution at various depths of submergence. These databank contributions are of special interest in traditional ship hydrodynamics. In Part 2, special focuses are made to elucidate the viscous and turbulent aspects of flow field. Finally Part 3 will deal with the visualization of instantaneous vortical flow to study the mutual interaction between vorticies shedded from the free-surface and the cylinder using a Particle Image Velocimetry.
On the Viscous Flow Around Breaking Waves Generated by a Submerged Cylinder(Part 2 : Aspects of Viscous Flow)
B.S. Hyun ; Y.H. Shin ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 1, 2000, Pages 91~98
The present paper is Part 2 of three-part paper for an experimental study on breaking waves generated by a submerged cylinder. Measurements of velocity and head loss profiles at the wakes of cylinder and breaker as well as the turbulent intensities in breaking region were made to elucidate the viscous aspects of breaking waves. Their mutual correlation is also investigated. It is found that the head loss profile is an excellent indicator of the strength and extent of breaker. Very high turbulent intensities measured at and just downstream of the breaker indicate the consequence of energy transfer of wave breaking into turbulence.
Development of Structural Analysis System of Bow Flare Structure(3) - Dynamic Structural Analysis -
S.G. Lee ; C.K. Park ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 1, 2000, Pages 99~110
The damages due to wave impact loads are largely affected by impact pressure impulse and impact load area. The objective of this study is, as the third step, to perform dynamic structural analysis of bow flare structure of 300,000 DWT VLCC using LS/DYNA3D code, and to verify its dynamic structural behaviors. The impact load areas of stiffener space
are applied to bow flare structure part with relatively flexible stiffeners, and with stiff members such as stringers, webs etc., respectively, under the wave impact load with peak height 6.5MPa, tail 1.0MPa, and duration time 5.0msec. Through the dynamic structural analysis in this study, it might be thought that the structural strength of bow flare structure is generally sufficient for these wave impact load and areas, except that large damages were found at bow flare structure area with flexible wide span stiffeners.
The Acoustic Characteristics of KRISO Cavitation Tunnel for Measurement of Underwater Noise
J.W. Ahn ; K.S. Kim ; J.T. Lee ; J.S. Kim ; S.Y. Kim ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 1, 2000, Pages 111~117
In the KRISO cavitation tunnel, the acoustic characteristics for the measurement of underwater noise are investigated, The background noise is measured and analyzed up to 100kHz at various test conditions. The noise level of the KRISO cavitation tunnel is compared with those of the other cavitation tunnels which have been designed for the noise study[HYKAT(Germany), GTH(France), etc.]. In order to investigate the background noise source. the coherence between structural vibration and noise level is analyzed using the B&K 3550 FFT analyzer. The experimental results show the possibility of the noise study and suggest the improvement plan.
Development of Optimum Structural Design System for Double Hull Oil Tankers
Chang-Doo Jang ; Seung-Soo Na ;
Journal of the Society of Naval Architects of Korea, volume 37, issue 1, 2000, Pages 118~126
An optimum structural design system for double hull oil tankers is developed based on the generalized slope deflection method which was previously proposed by the authors. For the optimization technique, the Hooke & Jeeves direct search method is applied to the minimum weight design problems with discrete design variables. A minimum weight design program is developed for the longitudinal members by the classification rules and for the transverse frames and the bulkhead members by the generalized slope deflection method. By this program, a minimum hull weight design of double hull oil tankers considering tank arrangement is performed and the design results are compared with existing ship. It is possible to find optimum tank arrangement and efficient types of hull structures for the minimum weight design of double hull oil tankers.