Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Society of Naval Architects of Korea
Journal Basic Information
Journal DOI :
The Society of Naval Architects of Korea
Editor in Chief :
Volume & Issues
Volume 35, Issue 4 - Nov 1998
Volume 35, Issue 3 - Aug 1998
Volume 35, Issue 2 - May 1998
Volume 35, Issue 1 - Feb 1998
Selecting the target year
Analysis of Three-dimensional Water Waves Created by a Hydrofoil Using a Higher-Order Boundary Element Method
Il-Ryong Park ; Ho-Hwan Chun ; Sung-Hwan Kim ; Dong-Dai Ha ;
Journal of the Society of Naval Architects of Korea, volume 35, issue 3, 1998, Pages 1~13
In the present paper, the hydrodynamic characteristics of three dimensional hydrofoils moving with a constant speed below the free surface using a higher-order boundary element method based on 9-node Lagrangian curvilinear elements are investigated. A bi-quadratic spline scheme is employed to improve the numerical results on the free surface. To validate the present scheme, the calculated results are compared with the analytic solutions for a submerged sphere and a spheroid showing a good agreement. For the validation of the hydrofoil study, the computed lift and drag of a hydrofoil having
section with aspect ratio(A.R.) of 4 are compared with the experimental data by Wadlin et al.. The comparison covers a number of variations of angle of attack and submergence depth. Then, using an A.R. hydrofoil with NACA0012 section, the free surface on the lift and drag are investigated and these are compared with the previous results. The wave elevations and patterns created by the aforementioned submerged bodies are also investigated with Froude numbers and submergences.
Analysis of Steady and Unsteady Performance for 3-D Surface Effect Wing
Il-Ryong Park ; Ho-Hwan Chun ;
Journal of the Society of Naval Architects of Korea, volume 35, issue 3, 1998, Pages 14~25
This paper describes the numerical modelling for the steady and unsteady forces of 3-D wings flying near the free surface based on a potential based panel method. For the steady problem where a wing flies over the fixed float surface, steady lift and drag forces are calculated for wings with and without end-plates having different sections, angle of attacks, aspect patios and flying heights. These numerical results are compared with the wind tunnel test results. The unsteady problem is treated as a boundary value one where a wing flies over the described wavy surface. The unsteady lift force variations of a wing due to different wave lengths and heights are calculated at different flying heights.
Development of Motion Control Techniques and Sea Trials of The Test Ship
J.W. Kim ; Y.G. Kim ; G.J. Lee ; C.Y. Lee ;
Journal of the Society of Naval Architects of Korea, volume 35, issue 3, 1998, Pages 26~37
In this study, the motion control techniques allied to the test ship NARAE are summarized and the results of sea trials are resented. NARAE adopted a hybrid hull form with lower hull and submerged foils. This type of ship has a substantial instability in heave, pitch and roll modes at the foil-borne stage due to little restoring force, so an active control is indispensable to keep the stability. 4-hydraulic actuators with servo valves were installed to drive foils, and several sensors were used to measure the motion of the ship. PID controller was adopted as a motion controller, and for the real-time control, Pentium-class industrial PC was used. Sea trials including take-off, landing, and banked turn maneuvering were carried out for a period of over 3 months and quite satisfactory results were obtained.
An Experimental Study on the Effects of Afterbody Appendages and Hull Form on the Manoeuvrability of a Container Carrier
Ho-Young Lee ; Deuk-Joon Yun ;
Journal of the Society of Naval Architects of Korea, volume 35, issue 3, 1998, Pages 38~45
In this parer, the effects of a skeg, rudder and stern hull form on the manoeuvrability of a container carrier with small length to draft ratio have been investigated through a series of model test. Rudder open water tests and PMM tests were carried out with varying rudder area, afterbody appendages and stern hull form to investigate their effects on the manoeuvrability. The MMG model developed in Japan was used for the manoeuvring simulation with experimentally obtained hydrodynamic coefficients. The result showed that the effects by the variation of stern profile and the skeg below stern bulb are much larger than those by any other types of appendages in improving directional stability of the vessel.
Development of a Direct Structural Analysis System for Floating Type Ocean Structures
Seong-Whan Park ; Jeong-Youl Lee ; Chae-Whan Rim ;
Journal of the Society of Naval Architects of Korea, volume 35, issue 3, 1998, Pages 46~53
The aim of the present study is to develop a direct structural analysis system for more reliable and effective structural safety estimation of floating tripe ocean structures. In this system, the following three modules are included; i.e., a rigid body motion analysis module based on the three dimensional panel method, a structural analysis module, and a stochastic analysis module based on short and long term spectral analysis techniques. The structural analysis module consists of the general purpose finite element analysis program NASTRAN and the automatic load data generation program LOADGEN. As an illustrative example, the developed system is applied to structural design of a PILOT Barge Mounted Plant(BMP). Results of the structural analysis are compared with those obtained using a two dimensional strip method.
Sensitivity Analysis of Vortical Hull Girder Vibration
Dae-Seung Cho ; Sa-Soo Kim ;
Journal of the Society of Naval Architects of Korea, volume 35, issue 3, 1998, Pages 54~61
This paper presents a prediction method of natural frequencies of vertical hull girder vibration based on design sensitivity analysis in case of design modification and the variation of loading condition. The resented method premises the vibration analysis by the transfer matrix method. Governing sensitivity equation is derived from the direct differentiation of state vector and transfer matrix to parameters and its transfer over all the hull girder elements. Derivatives of natural frequencies and mode shapes are determined by two trial calculation of the governing equation. Using the derivatives, the changes of natural frequencies and mode shapes can be predicted when mass and stiffness parameter's are changed. As results, it is possible to optimize ship structure as well as to avoid troublesome calculation in hull girder vibration analysis rationally and efficiently. To verify the accuracy and efficiency of the resented method numerical results obtained by both the sensitivity analysis and the ordinary reanalysis far a real ore/bulk carrier in case of the change of mass and stiffness parameters are compared.
A Study on Metallurgical Properties and Fatigue Strength depending on Bead Height in SAW Butt Joints
H.W. Lee ; Y.T. Shin ; J.U. Park ; H.G. Suk ;
Journal of the Society of Naval Architects of Korea, volume 35, issue 3, 1998, Pages 62~70
This paper is a study on the fatigue Strength depending on bead height. According to the AWS CODE D1.1, reinforcement shall not exceed 1/8"(3.2mm) in height. Most of the bead heights exceed AWS rule in actual welding. So we estimated the fatigue Strength of the as-welded specimens and the removed bead specimens of which height is 3mm with SAW 2 pole process. As a result, this paper presents that fatigue Strength is not concerned with as welded condition and removed 3mm bead height, also fatigue Strength obtained as welled specimens are satisfied with those proposed by the UK DEN, DNV and AWS.
Probabilistic Analysis of Coupled Axial and Torsional Vibration of Marine Diesel Propulsion Shafting System
S.Y. Ahn ;
Journal of the Society of Naval Architects of Korea, volume 35, issue 3, 1998, Pages 71~78
Recently, modern long-stroke diesel engines with small number of cylinders have been installed for energy saving and simpler maintenance. These kinds of low speed diesel engine produce large torsional vibration in the shafting, which induces the excessive vibratory stresses in the shafting and large propeller thrust variation. This thrust variation excites vibrations of the shafting and superstructure in the longitudinal direction. Up to now the deteriministic analysis of coupled vibration of marine shafting system has been performed. In this paper probabilistic analysis method of the marine diesel propulsion shafting system under coupled axial and torsional vibrations is presented. For the purpose of this work, the torsional and axial vibration excitations of engine and propeller are assumed to be probabilistic while the lateral excitation is assumed to be deterministic. The probabilistic analysis is based on a response surface and Monte-Carlo simulation. Numerical results based on the proposed method are compared with results calculated using the conventional deterministic analysis method. The results obtained make it clear that the proposed method gives a substantial increase in information about shafting behaviour as compared with the deterministic method.
A Development of Neurofuzzy System for a Conceptual Design of Ship
Soo-Young Kim ; Hyun-Cheol Kim ;
Journal of the Society of Naval Architects of Korea, volume 35, issue 3, 1998, Pages 79~87
The purpose of this paper is to develope a neurofuzzy system for a ship design which can determine efficiently design values e.g. principal dimensions and hull factors in a conceptual design. The neurofuzzy system for a ship design(NeFHull) applies a information about given input-output data to fuzzy theories and deals these fuzzificated values with neural networks, e.g. first, redefines normalized input-output data ad membership functions and then executes these fuzzficated information with backpropagation neural networks. We use a hybrid learning algorithm in the training of neural networks and examine the usefulness of suggested method through mathematical and mechanical examples.