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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 39, Issue 4 - Nov 2002
Volume 39, Issue 3 - Aug 2002
Volume 39, Issue 2 - May 2002
Volume 39, Issue 1 - Feb 2002
Selecting the target year
A Study on the Pressure Distributions of Horn Rudder Operating in Ship's Wake
Do-Sung Kong ; Jae-Moon Han ; Jae-Moon Lew ;
Journal of the Society of Naval Architects of Korea, volume 39, issue 2, 2002, Pages 1~10
DOI : 10.3744/SNAK.2002.39.2.001
Hull-propeller-rudder interactions are studied by the iterative computational procedures. Hull effects on the propeller are reflected through the effective velocities computed by the vortex ring method which used the measured nominal wake as input data. A potential based panel method has been developed to solve the propeller-rudder interactions using the obtained effective velocities. Steady flow characteristics around the rudder surface can be obtained by computing the induced velocities on the rudder by the propeller and vice versa are computed by the iterative manner until the converged solutions are obtained. Flow characteristics around the propeller and the rudder are measured by Laser Doppler Velocimetry(L.D.V.) in large cavitation tunnel at Samsung Heavy industries. The gap flow model is adopted to solve the characteristics of the horn rudder. Numerical results are compared with the experimental values and the computed velocity fields and pressure distributions with rudder angle on the horn rudder surface show good agreement with measured ones in large cavitation tunnel.
Hydroelastic Responses for a VLFS close to a Breakwater by the Velocity Potential Continuation and Singularity Distribution Method
Ho-Young Lee ; Young-Ki Kwak ; Jong-Hwan Park ;
Journal of the Society of Naval Architects of Korea, volume 39, issue 2, 2002, Pages 11~18
DOI : 10.3744/SNAK.2002.39.2.011
In this paper, the method calculating hydroelastic responses of very large floating structure close to a breakwater in waves is presented. The source-dipole distribution method is used to calculate the generalized radiation problem considering breakwater effects and the diffraction problem is analyzed by using the source-dipole distribution andvelocity potential continuation method. The response of a VLFS is approximated by anexpansion in terms of a free-free beam. Calculated model is a VLFS with 1000m in length in a sea with a straight breakwater. The vertical displacements and bonding moments around a VLFS are calculated by variations for distance between a VLFS and a breakwater and incident wave angle to know the effect of a breakwater.
A Study on the Crack Detection Using the Wavelet Transformation of Mode Shape for Hull Girder
Dae-Sung Lee ; Dae-Seung Cho ;
Journal of the Society of Naval Architects of Korea, volume 39, issue 2, 2002, Pages 19~27
DOI : 10.3744/SNAK.2002.39.2.019
The early damage detection of large structures is very important to prevent the disaster due to its global failure. In this paper, a crack detection method of the beam-analogy structure based on the wavelet transformation of mode shape is presented. The method can effectively detect the singularity of mode shape caused to the inconsistency of bending moment and shear force at the damaged part using the discrete wavelet of mode shape and its inverse transforms of detail components. To investigate the validity and the applicability of the presented damage detection method, numerical simulation and experiment are carried out for the idealized beam and the real ship structures.
A Development of Measurement and Comparison Technique for Large Curved Hull Pieces
Jong-Moo Lee ; Jong-Gye Shin ;
Journal of the Society of Naval Architects of Korea, volume 39, issue 2, 2002, Pages 28~33
DOI : 10.3744/SNAK.2002.39.2.028
The characteristics of hull-pieces are large quantity, comparatively large piece-size, and different each shape. For the more, in the forming process(including Line-Heating Process) of curved hull pieces, shape checking processes including initial shape measurement and forming shape measurement of the each pieces are needed to achieve a given accuracy. So, the forming process of large curved hull pieces needs efficient measurement and comparison technique to check the shape and ensure the forming-accuracy In this paper, we try to construct integrated S/W, H/W system for efficient measurement and comparison of large curved hull pieces, which can apply to above forming environment.
A Study on Automation of Steel Plate Forming by Heating Method
B.I. Lee ; H.S. Yoo ; G.G. Byun ; H.G. Kim ;
Journal of the Society of Naval Architects of Korea, volume 39, issue 2, 2002, Pages 34~44
DOI : 10.3744/SNAK.2002.39.2.034
Approximately 70 percent of shop's hull plate consists of three-dimensional curved shell. Concerning with the research on the automation of plate forming many studies have been carried out for the last decade. The purpose of this study is to develop the simulator of heating on the basis of the reasonable mechanical model representing a heating phenomenon. The beating experiment has been carried out with varying parameters influencing on the results of heating information at the kinematics analysis, simulatorestimate the shape of deformed plate that process along the processing information. When we get the initial shape and the object shape, we calculate the processing information first, using kinematics analysis. In a simulator we estimate deformed shape from the processing information. After this we compare deformed shape and object shape. If the error of deformed shape and object shape is in the proper limits, that information is determined the final processing information. Else we repeat the process changing variable.
A Mechanics-Based Determination of Heating Lines in Line Heating Process
Yong-Gyun Kim ; Jong-Gye Shin ;
Journal of the Society of Naval Architects of Korea, volume 39, issue 2, 2002, Pages 45~51
DOI : 10.3744/SNAK.2002.39.2.045
In Line Heating method, heating line is determined by kinematics analysis. But the heating line, which is solved by kinematics analysis, doesn't verify by the point of physical analysis and the choice problem in many heating line doesn't determine. In this paper, the simulator is developed. When we get the processing information at the kinematics analysis, simulator can estimate the shape of deformed plate that process along the processing information. When we get the initial shape and the object shape, we calculate the processing information first, using kinematics analysis. In a simulator, we estimate deformed shape from the processing information. After this we compare deformed shape and object shape. If the error of deformed shape and object shape is in the proper limits, that information is determined the final processing information. Else we repeat the process changing variables.
Analysis of the thermal fluid flow between the gas torch and the steel plate for the application of the line heating
Jong-Hun Woo ; Jong-Gye Shin ;
Journal of the Society of Naval Architects of Korea, volume 39, issue 2, 2002, Pages 52~60
DOI : 10.3744/SNAK.2002.39.2.052
Line heating is a forming process which makes the curved surface with the residual strain created by applying heat source of high temperature to steel plate. in order to control the residual strain, it is necessary to understand not only conductive heat transfer between heat source and steel plate, but also temperature distribution of steel plate. In this paper we attempted to analyze is temperature distribution of steel plate by simplifying a line heating process to collision-effusive flux of high temperature and high velocity, and conductive heat transfer phenomenon. To analyze this, combustion in the torch is simplified to collision effusive phenomenon before analyzing turbulent heat flux. The distribution of temperature field between the torch and steel plate is computed through turbulent heat flux analysis, and the convective heat transfer coefficient between effusive flux and steel plate is calculated using approximate empirical Nusselt formula. The velocity of heat flux into steel plate is computed using the temperature distribution and convective heat transfer coefficient, and temperature field in the steel plate is obtained through conductive heat transfer analysis in which the traction is induced by velocity of heat flux. In this study, Finite Element Method is used to accomplish turbulent heat flux analysis and conductive heat transfer analysis. FEA results are compared with empirical data to verify results.
A Study on the Fatigue Crack Propagation Analysis Using Equivalent Stress Distribution
C.W. Kim ; I.S. Nho ; K.S. Do ;
Journal of the Society of Naval Architects of Korea, volume 39, issue 2, 2002, Pages 61~68
DOI : 10.3744/SNAK.2002.39.2.061
From the viewpoint of linear fracture mechanics, the crack propagation behavior of two different structures having the same K-a relationship could be considered identical. In this study the stress distribution in an infinitely wide cracked plate with the same K-a relationship as in a real structure is defined as the equivalent stress distribution. Fatigue life of a real structural element can be predicted by applying the equivalent stress distribution to a simple structural element, and performing a fatigue crack propagation analysis. The K-a relationship for a structural member can be estimated by a finite element method or a simplified prediction method. The validity to obtain effective crack driving stresses by using the equivalent stress-distribution is examined.
Relations between Input Parameters and Residual Deformation in Line Heating process using Finite Element Analysis and Multi-Variate Analysis
Jang-Hyun Lee ; Jong-Gye Shin ;
Journal of the Society of Naval Architects of Korea, volume 39, issue 2, 2002, Pages 69~80
DOI : 10.3744/SNAK.2002.39.2.069
Sequential process of roll-bending and line heating has been used to deform the curved hull-plates in shipyards. A growing interest for the mechanization or automation of the line heating process has been noted. Relations between heating conditions and residual deformations are important components needed for the mechanization. The residual deformations are investigated by using a thermal elastic-plastic analysis based on the finite element analysis(FEA). Several experiments are also performed to examine the validity of the results of FEA. The input parameters of line heating are suggested by dimensional analysis of line heating. The dimensional analysis can extract the primary input-parameters of line heating. The relations between the heating conditions and the residual deformations are set up by multi-variate analysis and multiple-regression method. This study suggests a method for the relation between the heating conditions and the deformations lying under the line heating.