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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 31, Issue 4 - Nov 1994
Volume 31, Issue 3 - Aug 1994
Volume 31, Issue 2 - May 1994
Volume 31, Issue 1 - Feb 1994
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A Study on the Data Structure and Implementation Techniques for the Object Oriented Ship Structure Modeling
Seung-Wan Suh ; Won-Soo Kang ; Kyu-Yeul Lee ; Kyu-Ock Lee ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 1~11
The development of "Ship structural CAD system" has been performed in CSDP(Computerized Ship Design and Production) project to support ship structural design works. The procedures and contents of current design practice concerning the ship structural design were analyzed. To generate design information required at each design stage using the ship structural CAD system, the computerized model was created. To represent and implement the model information, a data structure which represents design concept as well as shape information was proposed using the concept of the product model. To embody the computerized model the object-oriented techniques were established to represent requirements of real world.
A Study on the Efficient Optimization Method by Coupling Genetic Algorithm and Direct Search Method
D.K. Lee ; S.J. Jeong ; S.Y. Kim ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 12~18
Optimization in the engineering design is to select the best of many possible design alternatives in a complex design space. In order to optimize, various optimization methods have been used. One major problem of traditional optimization methods is that they often result in local optima. Recently genetic algorithm based on the mechanics of natural selection and natural genetics is used in many application fields for optimization. Genetic algorithm is more powerful to local optima, but it requires more calculation time and has difficulties in finding exact optimum point in design variable with real data type generally. In this paper. hybrid method was developed by coupling genetic algorithm and traditional direct search method. The developed method finds out a region for global optimum using genetic algorithm, and is to search global optimum using direct search method based on results obtained from genetic algorithm. By using hybrid method, calculation time is reduced and search efficient for optimum point is increased.
A Representation of Product Model for the Piping System Based on the Object_Oriented Paradigm
Jong-Kap Lee ; No-Sang Park ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 19~30
The modeling of a product data is becomming more and more important in engineering environment, especially for the development of CAD/CAM system as a basis of computer integrated manufacturing system. Model is a formalized representation of the real world, and modeling is the task to identify, abstract, and formalize the product information into an unambiguous representation. In this study, the piping system, one of typical product of ship outfitting system, is modeled. The STEP idea is followed to provide a common mechanism to represent the product information throughout the life-cycle, and the object oriented paradigm is used in the analysis and design of the model. The definitions given within this model are independent of the specific application domain so that the same methodology can be used for other purpose.
A Study on Development of an Algorithm for Vertex Creation to Define Ship Hull Forms
Hyun-Kyoung Shin ; Sang-Sung Shin ; Kyu-Won Park ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 31~37
When a lot of input data are not distributed uniformly n a chord-span direction or when the given shape is complicated, it is very difficult to obtain an inverse matrix which represents the smooth Bi-cubic B-spline surface of the initial shape. To overcome this problem, we suggest image Surface Expansion Method(ISE Method) which is suggested for vertex creation of B-spline curves and surfaces. Its basic concept, convergency and verification are shown. Also B-spline curves and Surfaces represented by ISE Method were compared with those represented by the existing method which is based on the inverse matrix method, the pseudoinverse matrix method and the chord length approximation method for vertex yielding. Ship Hull Forms which have Knuckle, Bulbous Bow, Transom and Stern frame were represented by the ISE Method.
The Implementation Method of CIMS for Ship Manufacturing using STEP
S.B. Yoo ; J.W. Lee ; Y.M. Jeong ; D.Y. Yoon ; H.J. Kim ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 38~46
The role of CIMS(Computer Integrated Manufacturing Systems) is to integrate various applications throughout a product's life cycle. STEP is an international effort to standardize information models and interfaces so that independently developed applications can be easily integrated. A prototype for the Ship CIMS is built using STEP. In this prototype, the information model defined by EXPRESS is translated into database schemas. In this paper, we explain the operation of this prototype using the examples from two application programs, i.e., the Block Division System and the Erection System which are used for the process planning of ship manufacturing. As an example. Real data stored in a relational database system(Oracle) is presented in this paper.
Theoretical Analysis of Linear Maneuvering Coefficients with Water Depth Effect
In-Young Gong ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 47~58
Theoretical calculations are carried out for the estimation of linear maneuvering coefficients of a ship moving in shallow water region. Hydrodynamic forces and moments acting on a maneuvering ship are modelled based on a slender body theory, from which integro-differential equation for the unknown inner stream velocity is derived. Numerical algorithms fur solving this equation are described in detail. By considering water depth effects in the mathematical model, variations of maneuvering coefficients with water depth are studied. Programs are developed according to this method and calculations are done for Mariner, Series 60 and Wigley hull forms. For the verification of the programs, calculated results are compared with some analytic solutions and with published experimental results, which show good agreements in spite of many assumptions included in the mathematical model. It is expected that this method can be used as a preliminary tool for the estimation of maneuverability coefficients of a ship in shallow water region at its initial design stage.
A Study on the Propeller Blade Singing Place of an 86,000 Ton Deadweight Crude Oil Tanker
Dong-Hae Kim ; Kyoon-Yang Chung ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 59~64
A study was conducted to investigate the propeller singing place of an 86, 000 ton Deadweight Crude Oil Tanker. In preliminary study, proper use of finite element analysis was verified by comparing with the result of hammering test in the air. Then the finite element analysis was carried out for the blade in the water and compared with the noise measurement during sea trial, which enabled to confirm the local resonances of blade structure. Result of the study showed that the singing occurred most probably at trailing edges on the blade tip over 95% of propeller diameter. Owing to edge cutting of a successfoul remdial action, the singing excitation forces seemed to be reduced whereas the vibration characteristics of the blade was not changed.
Study on the Manoeuvring Characteristics of a Ship with Stern Bulb
Kyoung-Ho Sohn ; Gyoung-Woo Lee ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 65~79
In the present paper, An emphasis is laid upon effects of stern bulb on hydrodynamic property and manoeuvring performance. We carried out captive model tests in circulating water channel with two ship models of which the frame lines of aft bodies are different. such as normal stern form and stern form with bulb, but of which the other parts are exactly same. The tests conducted consist of hull resistance test, effective thrust measurement, oblique tow test, and measurements of factors related to rudder force. From the results of model tests, we discussed effects of stern bulb on hull forces and on hull-propeller-rudder interactions, comparing with normal stern form. Furthermore, we also discussed effects of stern bulb on course stability. turning ability. spiral characteristics and zig-zag manoeuvre by computer simulation. As a result, it is clarified that the adoption of stern bulb makes course stability the worse and turning ability the better. The difference of the hydrodynamic derivatives of naked hull between two ship forms cause the worse course stability of the ship with stern bulb. The differences of the effective inflow velocity to rudder and hull forces induced by steered rudder cause the better turning ability of the ship with stern bulb.
A Numerical Analysis of Free Surface Wave around a ship
Choon-Bum Hong ; Seung-Hee Lee ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 80~86
A numerical method for simulations of inviscid incompressible flow fields around a ship advancing on the free surface is developed. A body fitted coordinate system, generated by numerically solving elliptic type partial differential equations is used to conform the ship and free surface configurations. Three dimensional Euler equations transformed to the non-staggered body fitted coordinate system are discretised by finite difference method. Time and spatial derivatives are discretised by forward and centered differencings, respectively, and artificial dissipations are added to discretised convection terms for improvements of numerical stability. At each time steps, free surface elevations are recomputed to satisfy nonlinear free surface conditions. Poisson equations for pressure field are solved iteratively and the velocity field for next time step is extrapolated. To verify the developed numerical method, flow fields around a Wigley model are simulated(Fn=0.250-0.408) and compared with experimental data to show good agreements.
Computation of Turbulent Flow around Wigley Hull Using 4-Stage Runge-Kutta Scheme on Nonstaggered Grid
Suak-Hp Van ; Hyoung-Tae Kim ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 87~99
Reynolds Averaged Navier-Stokes equations are solved numerically for the computation of turbulent flow around a Wigley double model. A second order finite difference method is applied for the spatial discretization on the nonstaggered grid system and 4-stage Runge-Kutta scheme for the numerical integration in time. In order to increase the time step, residual averaging scheme of Jameson is adopted. Pressure field is obtained by solving the pressure-Poisson equation with the appropriate Neumann boundary condition. For the turbulence closure, 0-equation turbulence model of Baldwin-Lomax is used. Numerical computation is carried out for the Reynolds number of 4.5 million. Comparisons of the computed results with the available experimental data show good agreements for the velocity and pressure distributions.
Some Tests on Spray of a Prismatic Planing Hull
Mun-Keun Ha ; Michio Nakato ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 100~111
This study was carried out for understanding the characteristics of the spray around high speed vessels. Prismatic planing hull made of an acrylate board was used to the tests. The distribution of local spray velocity were estimated from the analysis of the spray visualization. A new test system for measuring the spray thickness is proposed, and was used to estimate the local spray thickness in the model. The pressure distributions on the bottom of the hull are measured and integrated to estimate the pressure drag of the model in the towing tests. Finally. the spray drag/lift component is separated from the total drag/lift on the prismatic hull. These test results show that the spray drag component on high speed vessels is relatively large and important in total drag.
Application of Multiple Regression Method to Prediction of Noise Level in Ship Cabins
Dong-Hae Kim ; Kyoon-Yang Chung ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 112~118
In this paper, statistical approach to prediction of A-weighted noise level in ship cabins. based on multiple linear regression analysis, is conducted. The best regression formula is composed of seven parameters of the deadweight, the type of ship, the location of engines and cabins, the type of deckhouse and the propeller skew angle. Verification work was carried out with other 210 cabins' data in 6 ships. As a result, the formula ensures the accuracy of 3 dB(A) in 77 % of cases.
An Estimation of Panel Deflection at Engine Room Upper Deck for the Ship Under Construction
Juh-H. Ham ; Ul-N. Kim ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 119~128
Deflection estimation at engine room upper deck panel is performed for the actual ship structure. These deflection behaviours are basically investigated from not only the data based on the full series results of nonlinear analysis using Incremental Galerkin's Method but also actual deflection data measured from damaged ship under construction in dry dock. The effects of residual stress, initial deflection and static loading are also included. The computed estimation results of upper deck plate panel including theme effects are shown that upper deck platings of new ship expected less deflection magnitude than damaged ship.
Modal and Structural Analysis of Laser Cutter
Kyu-Nam Cho ; Rae-Young Park ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 129~134
A Laser Cutter is designed for the precise fabrications in the shipyards recently. The cutter is a gantry type one with specified functions of movability and strength in order to satisfy the workability. The gantry frame should move with a certain velocity in a relatively short time for the proper cutting of the object materials. The gantry is fitted with ball screw and the acceleration field is formed by actuating this ball screw. The relative displacement should be within the allowable design criteria to make sure the precise cutting of the materials by the laser. In this paper, modal and structural analysis for a Laser Cutter which is commonly used in the shipyards, is carried out to check the design criteria of the system. The system is modeled by placing the proper shell and soils finite elements and fictitious mass properties to represent the real one. The way how to extract the loading conditions based on the given velocity criteria of the system is presented. Static structural analysis is performed and the results came out as expected. Modal analysis for finding eigen-values and mode shapes of the system is performed and it is shown that the time dependent dynamic analysis is unnecessary for this system for its operating circumstances.
A Vibration Problem and Countermeasures for the Deck House and Stern of a Ro/Ro Ship
Man-Cheol Han ; Sang-Heon Oh ; Il-Cook Baik ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 135~144
The coupled vibration of the deck house and stern structure, which was experienced on a 12,900 TDW Ro/Ro ship, has been studied. It was a large-scale vibration problem where the structure resonates with the propeller excitation at the first blade passing frequency. After discussing the structural characteristics of the ship, the vibration characteristics measured ducting the sea-trial are presented and compared with the analysis results which are based on a 3 dimensional finite element(FE) model. The FE model is also used to verify various reinforcement options and to predict their effectiveness. A substantial reduction or the vibration was confirmed during the sea-trial after installing a few selected reinforcement. The forced vibration response, which is computed using the FE model, is compared with the measured data. The change of the vibration characteristics according to loading conditions is also studied.
On the Prediction of Deformation of Welded Built-up Beams
Chang-Doo Jang ; Seung-Il Seo ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 145~153
In the fabrication of welded built-up beams, longitudinal deformation occurs due to welding, and this obstructs improvement of productivity and quality. In this study, to estimate the deformation due to welding, a simplified thermal elasto-plastic analysis method is proposed and verified by experiments. From the results of the simplified analysis, it is clarified that deformation coefficients defined in this study are the function of fabrication parameters. Based on this simplified analysis, a method to simulate the fabrication procedures for the built-up beams can be developed.
A Study on the Minimum Production Cost of Welded Built-up Beams
Chang-Doo Jang ; Seung-Il Seo ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 3, 1994, Pages 154~164
In this study, to find an economical production method which yields welded built-up beams with high quality, simulation techniques and optimization method are used. At first, fabrication variables such as welding current, voltage and speed and heated depth and breadth are selected and fabrication cost of a built-up beam is expressed by these parameters, which is optimized under the constraints. As advanced studies, total production cost including the fabrication cost and the material cost of the beam is expressed by the fabrication and design variables, and optimized with the design constraints by the class rules. In addition, assuming that heating for straightening is impossible. the optimization method of multi-objective functions based on the weighting method is applied to obtain the compromised optimal solutions of the total production cost and the welding deformation.