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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 30, Issue 4 - Nov 1993
Volume 30, Issue 3 - Aug 1993
Volume 30, Issue 2 - May 1993
Volume 30, Issue 1 - Feb 1993
Selecting the target year
Product Model for the Integration of Design and Manufacturing Information in Shipbuilding
S.B. Yoo ; J.W. Lee ;
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 1~12
The role of product model in CIM environemt(where such heterogenous application programs as CAD, CAE, CAM, Database, and Expert Systems are included) is system integration. Product model manages all the information related to manufacuring activities. This information includes shapes, operation, process, scheduling, quality, and mangement. Product model architecture includes product model kernel, object schema, model manipulation language, and user interface. Objects to be shared are defined using the model manipulation luage and the defintions are saved in the object schema. In this paper, we present the design and implementation of a prototype. In this prototype, application programs for CAPP(Computer Aided Process Planning) are used.
A Proposal to Construct a CAD System for the Preliminary Design of Ships
Soon-Hung Han ; Kyu-Yeul Lee ; Dong-Kon Lee ; Won-Soo Kang ;
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 13~23
To utilize the fast developing computer technologies for the preliminary design of ships a software system is under development. This paper describes strategies and methods taken in the process. Three key elements are identified which should be well harmonized in the system. First one is the conventional CAE part which is made of separate naval architectural modules. Second one is the design methodology which studies design procedure and working methods of human designers. Third one is supporting technologies coming from the computing fields, which are necessary for the development of such a system. Based on the study about three key elements several strategies and methods for the system development have been specified. Also same findings made in this process are introduced.
A Study on the Initial Hull Form Design by Using Form Parameters
Dong-Joon Kim ;
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 24~29
This paper describes a method for generating an initial hull form by using form parameters. As a mathematical representation of curves, B-spline curves are used as well as the polynomials used by Durand et al. The five basic control curves and the centerline contour are defined to give the boundary conditions for body plan by using above mentioned mathematical models. From these curves body plan is determined. Two additional curves which are concerned the position of matching point between the cylindrical form and the water line are proposed to get the preliminary faired water lines.
Knowledge-Based System for Rule Scantling Based on Object-Oriented Knowledge Representation and Open Architecture Concepts
Kyung-Ho Lee ; Dong-Kon Lee ; Soon-Hung Han ; Kyu-Yeul Lee ; Kyu-Chul Lee ;
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 30~36
An expert system to help a novice engineer in designing midship section is developed. The system is developed based on a general-purpose expert system shell, NEXPERT. Firstly, the design knowledge is extracted from an existing rule scantling program. The knowledge has been grouped and structured into a hierarchy by applying object-oriented concepts. Secondly, the knowledge base is integrated with a database of existing ships and engineering analysis modules through the Application Programming Interface(API)technique. Graphical User Interface which is developed using Motif wiget set is adopted. These altogether enable construction of an user friendly expert system.
A Characteristics of Non-linear Rolling of Ships in a Narrow Band Sea
Sun-Hong Kwon ; Yun-Cheol Na ; Dong-Dae Ha ;
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 37~42
In this study of statistical characteristics of roll response of ships to narrow band exciting moment generated by passing white noise through a linear filter is investigated. The parameters of linear filler are determined by comparing the results of exciting moment generated through filler equation tilth those evaluated from JONSWAP spectrum. The statistical results of the roll response of shops are presented.
On Numerical Method for Radiation Problem of a 2-D Floating Body
Y.S. Shin ; K.P. Rhee ;
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 43~53
There exist two difficulties in the nonlinear wave-body problems. First is the abrupt behavior near the intersection point between the body and the free surface, and second is the far field treatment. In this paper, the far field treatment is considered. The main idea is the Taylor series expansion of free-surface geometry and the application of F.F.T. algorithm. The numerical step is as follows. The velocity potential is expressed by the Green's theorem. and the solution is obtained by iteration method. In the iteration stage, the expressions by the Green's theorem are transformed to the convolution forts with the expansion of free surface by the wave slope. Here F.F.T. is applied, so the computing time can be of O(Nlog N) where N is the number of unknowns. The numerical analysis is carried out and the results are compared with other results in linear floating body problem and nonlinear moving pressure patch problem, and good agreements are obtained. Finally nonlinear floating body radiation problem is carried out with computing time of O(Nlog N).
Comparison of Free-Surface Boundary Conditions for Computing Wave Resistance
Suak-Ho Van ; Seung-Joon Lee ;
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 54~65
In computing the wave resistance numerically, satisfying the boundary condition(BC) on the body surface is not so difficult, and then what form of the BC on the free surface(FS) be used is a crucial question. To shed some light on this, we examine the various BC's on the FS, namely, the Poisson's, the Ogilvie's and the Dawson's BC, using the same panel method for submerged bodies in two-dimension. We also show the performance of the Poisson's BC for a submerged sphere and the Wigley hull. It seems that we are still in need of a theory which gives a BC on the FS more accurate than those tested, and more practically applicable than the exact nonlinear BC.
Effect of Flow Liners on Ship′s Wake Simulation in a Cavitation Tunnel
Jin-Tae Lee ; Young-Gi Kim ;
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 66~75
Flow control devices, such as flow liners, are frequently introduced hi a cavitation tunnel in order to reduce the tunnel blockage effect, when a three-dimensional wake distribution is simulated using a complete ship model or a dummy model. In order to estimate the tunnel wall effect and to evaluate the effect of flow liners on the simulated wake distribution, a surface panel method is adopted for the calculation of the flow around a ship model and flow liners installed in a rectangular test section of a cavitation tunnel. Calculation results on the Sydney Express ship model show that the tunnel wall effect on the hull surface pressure distribution is negligible for less than 5% blockage and can be appreciable for more than 20% blockage. The flow liners accelerate the flow near the after body of the ship model, so that the pressure gradient there becomes more favorable and accordingly the boundary layer thickness would be reduced. Since the resulting wake distribution is assumed to resemble the full scale wake, flow liners can also be used to simulate an estimated full scale wake without modifying the ship model. Boundary layer calculation should be incorporated in order to correlate the calculated wake distribution with tole measured one.
Numerical and Experimental Investigation on the Interaction of Subsurface Vortical Flows with a Free Surface
Mu-Seok Song ;
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 76~85
In order to predict the free surface signature of turbulent ship wakes two things are essential; a basic understanding of the mechanism of turbulent vortical flow/free surface interactions and a mathematical model to accurately predict the signature. The goal of the study described here is both to supplement experimental work to obtain basic understanding, as well as to condense this understanding in a model(or models) that captures the essential phenomena and thus allows predictions. To do so we followed two main paths guided by experimental observations. One is full simulations of the flow using the clavier-Stokes equations. The other is a vortex modeling, where the vortical structures of the flows are approximated by idealized structures, an the interaction assumed to be essentially inviscid. These approaches complement each other. Full simulations are only applicable to small scale phenomena, where the system is simple, and the Reynolds number is low. The vortex modeling, on the other hand, cannot represent essentially viscous aspects of the problem such as the effect of contamination gradient. Obviously, the modeling is what may eventually lead to a prediction method; the full simulations-too limited to mimic all but the simplest circumstances-are to aid and support the construction of realistic models. We address two-dimensional aspects of the vortex/free surface interaction first. Secondly we obtain some basic understanding of the interaction process through an experiment and then talk about several three-dimensional problems hoping to develop a successful prediction model.
Nonlinear Vortical Forced Oscillation of Floating Bodies
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 86~97
A numerical method is developed for the nonlinear motion of two-dimensional wedges and axisymmetric-forced-heaving motion using Semi-Largrangian scheme under assumption of potential flows. In two-dimensional-problem Cauchy's integral theorem is applied to calculate the complex potential and its time derivative along boundary. In three-dimensional-problem Rankine ring sources are used in a Green's theorem boundary integral formulation to salve the field equation. The solution is stepped forward numerically in time by integrating the exact kinematic and dynamic free-surface boundary condition. Numerical computations are made for the entry of a wedge with a constant velocity and for the forced harmonic heaving motion from rest. The problem of the entry of wedge compared with the calculated results of Champan and Kim. By Fourier transform of forces in time domain, added mass coefficient, damping coefficient, second harmonic forces are obtained and compared with Yamashita's experiment.
Numeric Analysis of 2-Dimensional Nonlinear Viscous Free-Surface Wave Problems
Y.H. Kim ;
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 98~111
Two-dimensional nonlinear free-surface wave problems are analyzed with consideration of viscosity. Navier-Stokes equation and continuity equation are solved by the application of Finite Analytic Method, and MAC scheme is used far the treatment of free surface. Surface tension effect is also considered and laminar flow is assumed. The free-surface waves in shallow water, the flows around a vortex-pair with free surface and the wave ahead of a rectangular body are simulated to test the present numerical scheme. In the shallow water problem, viscous effect due to the friction on the bottom is observed. In the second problem, the approach of a vortex-pair to the free surface is simulated to examine the interaction of vortex-pair with the free surface. In the third problem, the wave ahead of a semi-infinite floating body is simulated.
Application of a Potential-Based Panel Method for Analysis of a 2-Dimensional Cavitating Hydrofoils Advancing Beneath a Free-Surface
J.M. Lew ; C.S. Lee ; Y.G. Kim ;
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 112~122
A potential-based panel method is presented for the analysis of a partially or supercavitating two-dimensional hydrofoil at a finite submergence beneath a free surface, treating without approximation the effects of the finite Froude number and the hydrostatic pressure. Free surface sources and normal dipoles are distributed on the foil and cavity surfaces, their strength being determined by satisfying the kinematic and dynamic boundary conditions on the foil-cavity boundary. The cavity surface is determined iteratively as a part of the solution. Numerical results show that the wave profile is altered significantly due to the presence of the cavity. The buoyancy effect due to the hydrostatic pressure, which has usually been neglected in most of the cavitating flow analysis, is found playing an important role, especially for the supercavitating hydrofoil; the gravity field increases the cavity size in shallow submergence, but decreases it when deeply submerged, while the lift reduces at all submergence depth.
Hull Structural Design for 300K Double Hull VLCC
Hyon-Soo Bong ; Man-Soo Kim ; Jong-Koo Lee ;
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 123~131
Since the years of oil tanker production in the 70's, the concern of marine enviromental protection is worldwidely increased, at last it is compulsorily ruled to product the double hull tanker by International Maritime Organization(IMO). Throughout these informative years Daewoo Shipyard has developed the double hull VLCC for a future vessel. The paper presents hull design for 300K double hull VLCC which was carried out to satisfy with statutory requirement of it, focused the structural arrangement and direct calculation in cargo hold area.
Structural Safety Assessment of Independent Spherical LNG Tank(1st Report) - Fatigue Strength Analysis Based on the S-N Approach -
In-Sik Nho ; Yong-Yun Nam ; Ho-Sup Lee ;
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 132~140
The design of LNG ship needs very high level structural design/analysis technology compared with conventional ship types because it requires perfect security against the extremly dangerous and cryogenic cargo. Hence, present paper describes the general procedure of the structural safety assessment for independent tank type LNG ship, which contains following items. 1) Long term prediction of the wave induced stresses including ship motion analysis, structural analysis of hull and tank and stochastic analysis process of ocean waves. 2) Fatigue strength analysis of a tank structure based on the S-N approach. 3) Structural safety assessment against the fatigue crack propagation based on the LBF(Leak Before Failure) concept. The first report focuced on the item (1) (2) and example calculation was performed on a prototype LNG ship. The remained part will be covered by the second report.
A Simplified Approach to the Analysis of the Ultimate Compressive Strength of Welded Stiffened Plates
C.D. Jang ; Seung-Il Seo ;
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 141~154
In this paper, a method to calculate the ultimate compressive strength of welded one-sided stiffened plates simply supported along all edges is proposed. At first initial imperfections such as distortions and residual stresses due to welding are predicted by using simplified methods. Then, the collapse modes of the stiffened plate are assumed and collapse loads for each mode are calculated. Among these loads, the lowest value is selected as the ultimate strength of the plate. Collapse modes are assumed as follows ; (1) Overall buckling of the stiffened plate
Overall collapse due to stiffener bending (2) Local buckling of the plate part
Local collapse of the plate part
Overall collapse due to stiffener yielding (3) Local buckling of the plate part
Overall collapse due to stiffener berthing (4) Local buckling of the plate part
Local collapse of the plate part
Overall collapse due to stiffener tripping. The elastic large deflection analysis based on the Rayleigh-Ritz method is carried out, and plastic analysis assuming hinge lines is also carried out. Collapse load is defined as the cross point of the two analysis curves. This method enables the utimate strength to be calculated with small computing time and a good accuracy. Using the present method, characteristics of the stiffener including torsional rigidity, bending and tripping can also be clarified.
A Study for Web Frame Design on Engine Room Structure of Ship
J.J. Park ; B.S. Kang ;
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 155~160
A design method for web frame scantling on engine room structures was described. The parameters determining the scantling of web frame were studied on the basis of the empirical ship's data. It is found that the parameters determining the scanting of web frame consist of tween deck height, main engine and propeller excitation frequency, scantling draft, web frame spacing, the number of decks and main engine BHP etc. And a formula proposed by empirical ship's data was established in view points of static and dynamic structural behavior. In this study, it can be shown that at initial design stage, a method for web frame scantling of engine room structure is provided as very practical design processes.
The Integrity Assessment Method of Initailly Cracked Structural Components by Reliability Analysis
S.J. Yim ; T.U. Byun ;
Journal of the Society of Naval Architects of Korea, volume 30, issue 2, 1993, Pages 161~176
For the purpose of assessing structural integrity at a level of complexity and accuracy appropriate for the situation, integrity assessment methods are formulated with the following methods. One is three-tier assessment method of the revised BSI PD 6493 which considers stable crack growth effect, the others are limit load analysis which estimates the plastic collapse load and stability assessment method which considers stable crack growth of ductile material exactly using J-integral and tearing modulus. Besides, integrity assessments for center cracked panel(CCP) specimen and the circumferential through-cracked pipe are carried out and reliability analysis is accomplished by the first order reliability method which is one of the conventional reliability methods. Also the accuracy of the present method is verified by Monte Carlo method.