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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 Suitable Shape of Bottom for the Application of Air Cavity on Hull Bottom to the Practical Hull Form
Seok-Cheon Go ; Hyo-Chul Kim ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 3, 1999, Pages 1~7
This paper describes the modification of hull bottom for the air lubrication technique to the passenger boat in service at the Chung-Ju lake, which has a large beam-draft ratio. From numerical analysis of 2-D cavity problem by potential theory, the cavity shape, length and the pressure in cavity are estimated for the simplified geometry of hull bottom, and the non-dimensional parameters affecting air cavity phenomena are investigated. Extensive resistance tests for the model ship which has variation of step height and side strip have been performed to investigate the formation of air cavity and the drag reduction effectiveness. And also, the development of attached cavity to the bottom were observed from the flat bottom made by transparent acrylic plate. From this survey on the modification of bottom shape and the air lubrication technique, the total resistance of model ship could be reduced by about 25% at the design speed compared to the proto type hull form.
Experimental Study on Turbulent Structure of Flow around KRISO 3600TEU Container Double-deck Model
Hak-Rok Kim ; Sang-Joon Lee ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 3, 1999, Pages 8~14
The flor characteristics around the KRISO 3600TEU container ship model have been experimentally investigated in a subsonic wind tunnel. The mean velocity and turbulence characteristics in the stern and wake regions were measured using an x-type hot-wire probe. The flow characteristics in the stern and near wake regions revealed a complicated three-dimensional flow pattern. The measured results showed clearly the formation of longitudinal vortices and their effect on the flow pattern in the wake region. The shear layer developed along the ship model expands showly to the downward direction. The turbulence statistics measured can be used as comparative data of numerical simulations and provide insights into development of accurate turbulence models for the ship design.
Wind Tunnel Study on Flow Characteristics around KRISO 300K VLCC Double-body Model
Hak-Rok Kim ; Sang-Joon Lee ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 3, 1999, Pages 15~21
The flow characteristics around KRISO 300K VLCC double-body model have been experimentally investigated in a closed-type subsonic wind tunnel. The local mean velocity and turbulence statistics including turbulent intensity. Reynolds shear stress and turbulent kinetic energy were measured using a x-type hot-wire probe. The measurements were carried out at several transverse stations of the stern and near wake regions. The surface flow was visualized using on oil-film technique to see the flow pattern qualitatively. The flow in the stern and near wake region revealed complicated three-dimensional flow characteristics. The VLCC model shows a hook-shaped wake structure behind the propeller boss in the main longitudinal vortex region. The thin boundary layer at midship was increased gradually in thickness over the stern and evolved into a full three-dimensional turbulent wake.
Flow Measurements on the Propeller Plane Using Fiber Optics LDV at Towing Tank
J.E. Choi ; H.W. Seo ; K.S. Min ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 3, 1999, Pages 22~28
Flow measurements on the propeller plane of a 180,000 TDW Bulk Carrier model are carried out using a 3D fiber optics LDV at a towing tank. Mean velocities are successfully obtained. The turbulence characteristics such as Reynolds stresses, skewnesses, and flatnesses, are also investigated. However, those turbulence characteristics may include some errors due to the characteristics of the towing-tank experiments.
Theoretical Prediction of Noise Generated by Unsteady Loading of Marine Propellers
Chang-Sup Lee ; Chung-Ho Cho ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 3, 1999, Pages 29~40
A numerical method in frequency domain for the analysis of the acoustic wave equation governing the sound field generated by a non-cavitating propeller under a steady of unsteady loading condition is developed. Theory shows that only multiples of the blade passage frequency exist and that the wave number consists of the frequency component due to the nonuniformity of the wake and the Doppler effect originated from the rotation of the blades. Correlation with experiments for a two bladed propeller, designed to be load-free at a particular advance speed, indicate that the thickness effect can be significant in steady case, but can be negligible compared to the unsteady loading effect.
Development of a Ventilating Waterjet Propulsor for Super-High Speed Ships
J.T. Lee ; I.S. Moon ; Y.H. Park ; K.Y. Kim ; K.S. Kim ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 3, 1999, Pages 41~49
A feasibility study is performed for practical application of a Ventilating Water-Jet(VWJ) propulsor which attracts new attention as a candidate propulsor for super-high speed vessels. Super-cavitating foil sections are adopted for the rotor blades since the rotor is operating at ventilating condition. Wedge type and cavitator type foil sections are used for the design of rotor blades. Other geometric characteristics of rotors are selected from the Kaplan type ducted propeller rotors. The test section of KRISO cavitation tunnel is modified to perform open-water tests of the VWJ propulsors. The tests are performed both at fully-submerged and free-jet conditions. Ventilation occurred at the free-jet condition by sucking the air in the downstream side of the rotor, which easily develops as super-cavitation when the rotor operates at lower advance coefficients. Spoilers are attached at the trailing end of the pressure side of the blade section, in order to increase the lift force.
Design of 2-Dimensional WIG Section by a Nonlinear Optimization Method
Hee-Jung Kim ; Ho-Hwan Chun ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 3, 1999, Pages 50~59
This paper is concerned on the generation of an optimal section of wing in ground effect by a SQP method which is one of nonlinear optimization techniques. A potential panel method is used for the flow analysis and the ground effect is taken into account by an image method. The numerical method is first verified by an inverse problem where a shape of wing section is sought for the prescribed pressure distribution. The purpose of the present paper is to generate a wing section which can give a maximum lift subjected to the design constraints including the height stability which is important in the WIG design. The effect of the tail wing is also included.
Longitudinal Stability of a Wing-In-Ground Effect Craft
Ho-Hwan Chun ; Chong-Hee Chang ; Kwang-Jun Paik ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 3, 1999, Pages 60~70
The longitudinal stability characteristics of a Wing-In-Ground Effect Craft are quite different from that of the conventional airplane due to the existence of force and moment derivatives with regard to height. This stability characteristics plays a great role in designing a safe and efficient WIG due to its potential danger in sea surface proximity. The static and dynamic stability criteria are derived from the motion equations of WIG in the framework of small disturbance theory and discussed in the paper. The static and dynamic stability analyses of a 20-passenger WIG are conducted based on the wind tunnel test data and the dynamic motion behaviors are investigated for the change of the design parameters. Finally, the flying quality of the 20-passenger WIG is analysed at the cruising condition according to the military regulations.
A Study on the Nonlinear Rolling Motion of Ship Using Basins of Attraction and Attractors
H.S. Lee ; S.H. Kwon ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 3, 1999, Pages 71~82
Irregular motions of nonlinear dynamic system are the result of an intrinsic characteristics that the system have, and sometimes occur unpredictable large motion. For a ship in a regular seaway, the capsizing occur because of this unexpectable motion. So, from the safety's point of view, nonlinear ship motions should be treated carefully. In this study, stable and unstable regions are investigated firstly under the variation of a control external force. Secondly, we consider the attractors to know how ship motions of the stable region that does not undergo capsizing change. Thirdly, bifurcation diagram is considered to study the range in detail where nonlinear chaotic motions are occurred.
An Analysis of the Hydroelastic Response of Large Floating Structures in Oblique Waves
In-H. Sim ; Jae-D. Yoon ; Hang-S. Choi ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 3, 1999, Pages 83~92
In this paper, the fluid-structure interaction of large floating structures has been rigorously analyzed and the shear effect on the structural deformation has been investigated in oblique waves. A constant panel method(CPM) based on the Green function method is implemented for computing the hydrodynamic pressure, while a finite element method(FEM) is applied for the structural response based on the Mindlin plate theory with including shear deformation. In order to validate the method, we compared numerical results with experimental ones of Mega Float carried out by Yago & Endo in head waves. General behavior shows good agreement but the local displacement at the ends is slightly different. The numerical results show that the radiation pressure due to the fluid-structure interaction is locally larger than that of wave excitation and mooring devices greatly reduce the response. It is observed that the shear effects among the total deformation constitutes about 4% in the case of Mega Float in oblique waves.
A Study on the Basic Architecture of an Agent System for Agent-based System Integration
Sang-Uk Lee ; Kyu-Yeul Lee ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 3, 1999, Pages 93~106
In this paper, the basic architecture of an agent system was designed and a KQML(Knowledge Query and Manipulation Language) handler was implemented to handle 'tell', 'ask', 'handles' and 'interested' KQML performatives. The basic architecture of an agent system consists of a KQML handler, a KIF interpreter and a Flow control code. Agents use KIF(Knowledge Interchange Format) to represent the actual knowledges that are transmitted. They communicate others via an external language called KQML, which contains contents of messages written in KIF. The KQML handler controls communication. Contents of messages through it are stored and interpreted by the KIF interpreter. The flow control code controls the flow of program and information and performs engineering tasks. It gets knowledges from the knowledge base of the KIF interpreter and the other agents.
Application of Design Axiom to Marine Design Problems
Y.S. Song ; Y.S.Yang ; B.S. Jang ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 3, 1999, Pages 107~114
Design Axiom proposed by N. P. Such consists of Independence Axiom & Information Axiom. Based on the Independence Axiom, it is very useful specially for early design stage such as conceptual design to generate the design alternatives by considering both functions and structures of product. Since the Information Axiom shows that the design solution should have a least information to be the best one among the many alternatives, this axiom can be used for the best selection purpose during the preliminary design stage. In this paper, the possibility of Design Axiom in marine design application is checked by carrying out three examples of marine design. In the conceptual design of thruster, it is proven to use the Independence Axiom very effective by relating directly functional requirements with design parameters, one by one. In main engine selection example, Information Axiom is used to select best solution among alternatives by choosing the one having the minimum information quantity. For similarity based design in which the selection of changing design variables and the amount of those are important, it is proved that design axiom applied to Barge design case would be very effective and useful. As functional requirements and constrains were not clarified in early design stage, design axiom shows some difficulty for larger system design like ship which is basically carried out by an incremental and iterative process.
Ship Safety Assessment and Salvage Assistance System
Kyung-Ho Lee ; Dong-Kon Lee ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 3, 1999, Pages 115~121
Marine casualties of dangerous cargo carriers lead to not only the loss of human life and properties, but also marine pollution caused by spilled oil and hazardous cargo. So the prevention of marine casualties and emergence response to minimize pollution are very important problems to be settled. But until now, most of salvage assistance jobs have been done based on rule of thumb without any technical support. It is not easy to cope with the incidents safely and rapidly under the current situation. The purpose of this paper is to develop a systematic and engineering salvage assistance tool available in the casualty sites. This paper contains the construction of salvage system, classification of technical items, and prototype system for the safety assessment. The developed system enable a salvage engineer in his/her salvaging jobs to perform safely and promptly.
An Assembly Simulation of a Plane Block with Gravity and Welding Deformations
Jae-Gyou Roh ; Jong-Gye Shin ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 3, 1999, Pages 122~133
Overlap, excessive wide gaps, and errors between blocks during erection process increases cost and man-hour. In this paper, a system to simulate the assembly process is suggested and a plane block assembly of welding deformation with gravity is simulated in consideration of assembly order, deformations and errors occurring in the cutting and forming processes are not considered and welding deformations are acquired by equivalent stiffness and load method from experiments and hull double bottom plane block is assembled on a assembly order by panel method. It is certified that according to the order of assembly, intermediate product shape affects rigidity which affects welding deformations. Assembly order must be considered in the assembly process. It is certified that the gravity has important role in the assembly process.
A Determination of Approximated Cylindrical Surfaces of Doubly Curved Surfaces for the Least Line Heating
Dae-Kyu Yun ; Jong-Gye Shin ; Cheol-Ho Ryu ;
Journal of the Society of Naval Architects of Korea, volume 36, issue 3, 1999, Pages 134~143
The ship's bows and sterns are assembled with the curved blocks. In shipyards, the roller bending and the line heating or others are being used to fabricate such doubly curved shell. Firstly, the cylinder- or cone-type is formed through the roller bending, and then, the line heating is implemented to form the rest. This paper presents an algorithm to determine the direction for the roller bending and the shape to be formed as fabrication information. The direction for the roller bending is determined with Gauss mapping of the desired surface and the shape to form is calculated by comparing the bent shape with the desired shape.