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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 32, Issue 4 - Nov 1995
Volume 32, Issue 3 - Aug 1995
Volume 32, Issue 2 - May 1995
Volume 32, Issue 1 - Feb 1995
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Numerical Representation of the Hull Form using NURBS Curve
Hyun-Cheol Kim ; Soo-Young Kim ;
Journal of the Society of Naval Architects of Korea, volume 32, issue 1, 1995, Pages 1~8
This paper presents possibilities of a numerical hull form representation in the form of curve designs, which require a variety of form variations. The numerical representation method of the hull form is developed using NURBS curve with sufficient continuity and local variation.
Erection Process Planning & Scheduling using Genetic Algorithm
J.W. Lee ; H.J. Kim ;
Journal of the Society of Naval Architects of Korea, volume 32, issue 1, 1995, Pages 9~16
The erection process planning is to decide erection strategy and sequence that satisfies dock duration. The erection scheduling is to decide erection date of each block. The load profile varies according to scheduling and it is related to building cost. It must be possible to simulate the various combinations of process plan and schedule for optimal planning. To develop the process planning system for optimal planning, the system that generate the sequence of erection automatically and the load leveling system are required. This paper suggests the method that generates the erection sequence. The load leveling should be done to all the ships in the same dock batch to get reliable results. In this case since the search space is very large, efficient optimization method is needed Our research achieved the load leveling system using Genetic Algorithm. This system made it possible to simulate various process plans to which schedule is considered.
Automation of Detail Structural Design Process using a General-Purpose CAD System
Hwa-K. Lim ; Heung-W. Suh ; Duck-Y. Yoon ;
Journal of the Society of Naval Architects of Korea, volume 32, issue 1, 1995, Pages 17~24
In this paper, it is studied the design automation method in detail structural design stage using a general-purpose CAD system. It is observed that the macro function with parametric concept is very useful in detail structural design. We applied this concept to transverse web frame, slot hole and collar plate, and bracket modeling.
Reliability Analysis of Ship′s Longitrdinal Strength for the Rational Ship Structural Design
Oi-H. Kim ; Byung-J. Kim ;
Journal of the Society of Naval Architects of Korea, volume 32, issue 1, 1995, Pages 25~36
The application of the reliability analysis is investigated as a probabilistic approach to the assessment of ship's structural strength and to the establishment of design format for longitudinal strength. Reliability analyses are carried out for 34 ships of tankers and bulk carriers built in HHI for some failure modes such as tensile yielding, compressive buckling and ultimate strength of hull girder. The safety assessment of each ship, the calculation of sensitivity factors and the derivation of target reliability index are performed. As results. the difference of reliability indices among ships is great for all modes. To provide more uniform levels of safety the establishment of new strength criteria using partial safety factors is performed. The partial safety factors for the design format are obtained according to the AFOSM method and the reliability-conditioned(RC) method. Finally, a design format using partial safety factors has been proposed. We could find out that new strength criteria can produce consistent reliability indices which are close to the target value.
Analysis of Random Ship Rolling Using Partial Stochastic Linearization
Dong-Soo Kim ; Won-Kyoung Lee ;
Journal of the Society of Naval Architects of Korea, volume 32, issue 1, 1995, Pages 37~41
In order to analyze the rolling motion of a ship in random beam waves we use the partial stochastic linearization method. The quadratic damping and the nonlinear restoring moments given by the odd polynomials up to the 11th order are added to a single degree of freedom linear equation of roll motion. The irregular excitation moment is assumed to be the Gaussian white noise. The statistical characteristics of the response by the partial stochastic linearization method is compared with results by the equivalent linearization method and Monte Carlo simulation. It is fecund that the partial stochastic linearization method is not necessarily superior to the equivalent linearization method.
Analysis of Steady and Unsteady Flow Around a Ship Using a Higher-Order Boundary Element Method
Sa-Y. Hong ; Hang-S. Choi ;
Journal of the Society of Naval Architects of Korea, volume 32, issue 1, 1995, Pages 42~57
An efficient and accurate scheme has been constructed by taking advantages of the hi-quadratic spline scheme and the higher-order boundary element method selectively depending on computation domains. Boundary surfaces are represented by 8-node boundary elements to describe curved surfaces of a ship and its neighboring free surface more accurately. The variation of the velocity potential complies with the characteristics of the 8-node element on the body surface. But on the free surface, it is assumed to follow that of the hi-quadratic spline scheme. By which, the free surface solution is free from numerical damping and has better numerical dispersion property. As numerical examples, steady and unsteady Neumann-Kelvin problems are considered. Numerical results for a submerged spheroid, Series 60(
) and a modified support the proposed method. Finally, a new upstream radiation condition is derived using a wave equation operator in order to deal with problems for subcritical reduced frequency. The relevance of this operator has been confirmed in the case of unsteady Kelvin source potential.
Numerical Simulation of Wave Motions in Ideal Fluid of a Finite Depth
Boris Ye. Protopopov ;
Journal of the Society of Naval Architects of Korea, volume 32, issue 1, 1995, Pages 58~69
The present paper is devoted to constructing a numerical algorithm for solving un steady problems on generation, propagation and interaction of nonlinear waves at a surface of ideal fluid, within the framework of the potential-flow model. The numerical scheme is implicit. with non-linearity iteration at every step of time. the finite-difference method with boundary-fitted coordinates are presented in favor for validity and high efficiency of the numerical model developed. Among these arguments, there are the results of calculations of two test problems-on stretching of a liquid ellipse and on wave generation by lifting a portion of a bottom.
Numerical Analysis of the Ocean Tidal Current Considering Sea Bottom Topography
B.S. Yoon ; .H. Rho ;
Journal of the Society of Naval Architects of Korea, volume 32, issue 1, 1995, Pages 70~82
A multi-layer simulation program is developed to estimate the ocean current considering sea bottom geometry. The so-called
coordinate system is introduced in vertical direction to describe sea bottom topography more accurately and effectively. Leapfrog scheme combined with Euler backward scheme is used to reduce computation error which may be possibly accumulated in time evolution by Leapfrog scheme alone. In this paper, very simple examples of rectangular basins with various bottom geometries were taken and the effect of sea bottom geometry on vertical structure of the ocean tidal current and its direction were investigated. Through comparisons between the present three dimensional calculation in which bottom topography is directly taken into consideration and the two dimensional calculation in which depth average concept is employed, it was found that magnitude of surface current and its direction could be largely affected by the sea bottom topography, particularly in shallow region with complex bottom shape.
Numerical Analysis and Experimental Investigation of Duct Flows of an MHD Propulsion System
J.W. Lee ; S.J. Lee ; C.M. Lee ;
Journal of the Society of Naval Architects of Korea, volume 32, issue 1, 1995, Pages 83~93
A numerical and experimental investigation on the flow characteristics in the rectangular duct of an MHD propulsion system has been carried out. In numerical analysis, three-dimensional, steady-state, viscous, incompressible electrically conducting fluid flow under the influence of uniformly applied magnetic and electric fields was treated using a finite-difference technique. It was found from the numerical study that when the Lorentz force is weak, the typical parabolic velocity profile under a laminar flow condition changes to an M shaped profile near the electrode region and that the pressure increases linearly from the inlet toward the outlet of the MHD duct under constant electro-magnetic field. In experiment, thrust of the MHD propulsion system can be controlled easily by varying electrode current. The measured pressure gradient along the MHD duct is proportional to the Lorentz force, which is in agreement with the numerical results.
Development of Active Control System for Structural Vibration Using a Hydraulic Actuator
S.J. Moon ; T.Y. Chung ;
Journal of the Society of Naval Architects of Korea, volume 32, issue 1, 1995, Pages 94~102
The active control system of structural vibration using a hydraulic actuator is developed. The developed system consists of three parts : a hydraulic unit, an actuator unit and a control unit. Structural vibration is sensored by the accelerometer attached to the structure and reduced by the optimally controlled motion of active mass giving anti-phase inertia force to the structure. It is experimentally confirmed that the vibration level of model structure is reduced to about 1/6 by the developed active control system.
Collision Strength Analysis of Double Hull Tanker
J.K. Paik ; P.T. Pedersen ;
Journal of the Society of Naval Architects of Korea, volume 32, issue 1, 1995, Pages 103~117
A design-oriented method for analysis of the structural damage due to ship collisions is developed by using the idealized structural unit method(ISUM). The method takes into account yielding, crushing, rupture, the coupling effects between local and global failure of the structure, the influence of strain-rate sensitivity and the gap/contact conditions. The method is verified by a comparison of experimetal and numerical results obtained from test models of double-skin plated structures in collision/grounding situations with the present solutions. As an illustrative example, the method has been used for analyses of a side collision of a double-hull tanker. Several factors affecting ship collision response. namely the collision speed and the scantlings/arrangements of strength members, are discussed.
The Shock and Fracture Analysis of Ship Structure Subject to Underwater Shock Loading
Kie-Tae Chung ; Kyung-Su Kim ; Young-Bok Kim ;
Journal of the Society of Naval Architects of Korea, volume 32, issue 1, 1995, Pages 118~131
The shock fracture analysis for the structures of navy vessels subject to underwater explosions or of high speed vessels frequently subject to impact loads has been carried out in two steps such as the global or macro analysis and the fine or micro analysis. In the macro analysis, Doubly Asymptotic Approximation(DAA) has been applied. The three main failure modes of structure members subject to strong shock loading are late time fracture mode such as plastic large deformation mainly due to dynamic plastic buckling, and the early time fracture mode such as tensile tearing failure or transverse shear failure. In this paper, the tensile tearing failure mode is numerically analyzed for the micro analysis by calculating the dynamic stress intensity factor
, which shows the relation between stress wave and crack propagation on the longitudinal stiffener of the model. Especially, in calculating this factor, the numerical caustic method developed from shadow optical method of caustic well known as experimental method is used. The fully submerged vessel is adopted for the macro analysis at first, of which the longitudinal stiffener, subject to early shock pressure time history calculated in macro analysis, is adopted for the micro analysis.
A Structural Analysis of Sandwich Plate with Unsymmetrical FRP Thick Faces
Ik-Tai Kim ; Ki-Sung Kim ;
Journal of the Society of Naval Architects of Korea, volume 32, issue 1, 1995, Pages 132~140
The structural behavior of sandwich plates with unsymmetricaly thick faces are analysed using Raleigh-Ritz Energy method by comparing the bending stresses, shear stresses, local bending stresses, membrane stresses of skin and core materials including local bending effect. As for sandwich materials, the combination of two types of face materials and three types of core materials are used in the analysis.
Plastic Buckling Analysis of Rectangular Plates Considering Plastic Compressibility
Chan-Ho Shin ; Young-Bok Kim ;
Journal of the Society of Naval Architects of Korea, volume 32, issue 1, 1995, Pages 141~146
In this study the plastic buckling analysis of a simply supported plate under biaxial compression/tension loading is carried out considering the plastic compressibility. Plastic buckling of a biaxially loaded rectangular plate is governed by two kinds of mechanism, the tension strengthening and plastic weakening under which the optimal combination of tension and compression is obtained for the buckling strength. To consider the plastic compressibility, the Drucker-Prayer plastic potential is employed. General eigenvalue equations are derived for a rectangular plate within the framework of small strain plasticity and isotropic hardening.