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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Ocean Engineering and Technology
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Journal DOI :
Korean Society of Ocean Engineers
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Volume & Issues
Volume 16, Issue 6 - Dec 2002
Volume 16, Issue 5 - Oct 2002
Volume 16, Issue 4 - Aug 2002
Volume 16, Issue 3 - Jun 2002
Volume 16, Issue 2 - Apr 2002
Volume 16, Issue 1 - Feb 2002
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On an Analysis of Reflection and Transmission Coefficients by a Vertical Slit Plate
Journal of Ocean Engineering and Technology, volume 16, issue 3, 2002, Pages 1~7
In this paper, a numerical model to analyze the performance of a vertical slit-type wave absorber is developed under the assumption of inviscid water waves. The formulation combines the linear potential theory with a semi-empirical description of the eddy-shedding at a slit-type wave absorber. We investigated the reflection coefficients over a wide frequency range for a vertical slit-type wave absorber both with and without a solid rear wall. Model test was conducted at KRISO' s two dimensional wave tank to validate the theoretical results. It is found that the agreement between theoretical results and experimental data is surprisingly good. We found that the wave absorbing system using a vertical slit plate has sufficient potentials for breakwaters for cean development
On the Time-Mean Drift Force Acting on a Floating Offshore Structure in Wave
Journal of Ocean Engineering and Technology, volume 16, issue 3, 2002, Pages 8~18
Formulation of the far-field method for the prediction of time-mean hydrodynamic force and moment acting on a 3-D surface-piercing body in waves is reviewed. It is found that the inequality between the weight of the floating body and its buoyancy force permits the replacement of the fluid particles inside the control surface by the fluid particles outside the control surface. Under such circumstances, momentum exchanges across the control surface make the time-mean value of the time rate of the momentum of the fluid inside the control surface non-vanishing. It is a second-order quantity which is hard to calculate by the far-field method. The drift forces and moments on half-immersed ellipsoids are calculated by both the far-field method and the near-field method. The discrepancy between two numerical results is presented and discussed.
A Study on the Floating OWC Chamber Motion in Waves
Journal of Ocean Engineering and Technology, volume 16, issue 3, 2002, Pages 19~27
The motion of a floating OWC chamber in waves is studied taking account of fluctuating air pressure in the air chamber. An atmospheric pressure drop occurs across the upper opening of the chamber which causes not only hydrodynamic but also pneumatic added mass and damping forces to the floating chamber. A velocity potential in the water due to the free surface oscillating pressure patch is added to the conventional radiation-diffraction potential problem. the potential problem inside the chamber is formulated by making use of the Green integral equation associated with the Rankine Green function wile the outer problem with the Kelvin Green function. The two integral equations are solved simultaneously by making use of a matching boundary condition at the lower opening of the chamber to the outer water region. The chamber motion in the frequency domain is calculated for various values of parameters related to the atmospheric pressure drop. The present methods can also be sued for the analysis of air-cushion vehicle motion as well as for the design of a floating OWC wave energy absorber.
A Study on an Optimized Constant Pitch Propeller
Journal of Ocean Engineering and Technology, volume 16, issue 3, 2002, Pages 28~33
Optimization of marine propellers of constant pitch is studied, with the help of the infinite dimensional optimization (Jang and Kinoshita, 2000a), which is based on the Hilbert space theory. As a numerical example, the MAU type propeller is considered and used as he initial guess for the optimization method. The numerical computations for an optimal marine propeller are performed for the constant pitch distribution. In addition, a new optimization is suggested with the constraint of constant pitch during optimization.
Unsteady Interaction of the Surface Gravity Waves with the Nonuniform Current
Lee, Kwi-Joo ; Kim, Kyoung-Hwa ; Ra, Young-Kon ; Shermeneva, M.A. ; Shugan, I.V. ;
Journal of Ocean Engineering and Technology, volume 16, issue 3, 2002, Pages 34~39
Experimental Study for Hydraulic Characteristics as the Permeable Underlayer Thickness of Rubble mound Structure
Journal of Ocean Engineering and Technology, volume 16, issue 3, 2002, Pages 40~45
In this study, the effects on hydraulic characteristics are discussed as the permeable underlayer thickness of the rubble mound structure changes. A series of hydraulic experiments were performed and wave run-up, reflection and set-up were investigated. Result indicated that wave run-down was affected by the water out from the permeable underlayer during down-rush. As the thickness increased, relative wave run-up decreased.
Hydraulic Characteristics of Permeable Breakwater in relation to the internal Waterlevel Fluctuation
Journal of Ocean Engineering and Technology, volume 16, issue 3, 2002, Pages 46~53
In the study, the interaction characteristics among incident waves, run-up and internal waterlevel at core layer of breakwaters were investigated. The effect of core materials on the internal waterlevel characteristics are also discussed using the results with both regular and irregular wave tests. The main results obtained are as follows; The higher internal waterleve was observed under the permeable breakwater with core layer of the lower permeability than with the higher one. And, the internal waterlevl decreased as far as the distance from the toe. In the irregular wave test, the grouping characteristics of incident waves make large fluctuation of the waterlevel. Especially, breakwaters internal waterlevel appeared to affect the hydraulic characteristics on slope.
A Study on the X-ray Diffraction Analysis and the Fatigue Crack Growth Behavior for the Gas Piping Material
Journal of Ocean Engineering and Technology, volume 16, issue 3, 2002, Pages 54~58
This study investigates a relationship between fracture mechanics parameters (Stress Intensity Factor Range: ΔK, Maximum Stress Intensity Factor; Kmax) and X-ray parameters (residual stress:
r half-value breadth: B) for SG365 steel at elevated temperature up to 30
. The fatigue crack propagation test were carried out and X-ray diffraction technique according to the direction of crack length was applied to fatigue fractured surface. The residual stress on the fracture surface was found to increase at low ΔK region, to reach a maximum value at a certain value of Kmax or ΔK and then to decrease. Residual stress was independent of stress ratio by arrangement of ΔK and half value breadth were independent of the arrangement of Kmax. The equation of
r-ΔK was established by the experimental data. therefore, fracture mechanics parameters could be estimated by the measurement of X-ray parameters.
Creep Behavior of High Temperature Prestrain in Austenitic 25Cr-20Ni Stainless Steels
Journal of Ocean Engineering and Technology, volume 16, issue 3, 2002, Pages 59~64
In the present study, we examined the influence of prestrain on creep strength of Class M alloy(STS310S) and Class A(STS310J1TB) alloys containing precipitates. Prestrain was given by prior creep at a higher stress than the following creep stresses. Creep behaviour before and after stress change and creep rate of pre-strained specimens were compared with that of virgin specimens. Pre-straining produced the strain region where the strain rate was lower than that of a virgin specimen both for STS310J1TB and STS310S steels. The reason for this phenomenon was ascribable to the viscous motion of dislocations, the interaction between dislocations and precipitates in a STS310J1TB steel, and the interaction of dislocations with sub-boundaries in a STS310S steen which has the higher dislocation density and smaller subgrain size resulted from pre-straining at higher stress.
Conceptual Design of G/T25,000 Class Cruise Ship for Domestic Coastal Voyage in Korea
Journal of Ocean Engineering and Technology, volume 16, issue 3, 2002, Pages 65~71
From the definition of the cruise ship mission based on the investigation of the customer needs and statistical estimates and to design of the residence area of the cruise ship, in this study a conceptual design of the traditional ship parts (the lower hull) was carried out. for the light weight estimation of the cruise ship, several methods that have been used for commercial ships were evaluated to adapt for the cruise ship, the main particulars of the ship were determined with the light weight estimation and the assumed dead weight. From these main particulars of the ship, the hull form was developed with CFD verification and the general arrangement for the lower hull was achieved. For several loading conditions the intact stability of ship was checked.