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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 19, Issue 6 - Dec 2005
Volume 19, Issue 5 - Oct 2005
Volume 19, Issue 4 - Aug 2005
Volume 19, Issue 3 - Jun 2005
Volume 19, Issue 2 - Apr 2005
Volume 19, Issue 1 - Feb 2005
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Numerical Simulation on Laminar Flow past a Rotating Circular Cylinder
Park, Jong-Chun ; Moon, Jin-Kook ; Yoon, Hyun-Sik ; Lee, Byung-Hyuk ; Chun, Ho-Hwan ; Suh, Sung-Bu ;
Journal of Ocean Engineering and Technology, volume 19, issue 3, 2005, Pages 1~10
The effect of rotation on the unsteady laminar flaw past a circular cylinder is numerically investigated in the present study. The numerical solutions for the 2D Navier-Stokes equation obtained, using two different numerical methods. One is an accurate spectral method and the other is a finite volume method(FVM). First, the flaw around a stationary circular cylinder is investigated to understand the basic phenomenon of flaw separation and bluff body wake. Next, the flow characteristics of the laminar flow, past a rotating circular cylinder, are investigated, using a FVM developed in this study. By the effect of rotation, it is seen that values of lift increase, while the values of mean drag decrease. Further, the criteria of angular velocity, at which the Karman vorteces disappear, is also determined.
A Study of Pneumatic Reaction Force of Air Chamber for an OWC Type Wave Energy Device by Forced Heave Experiments
Hong, Seok-Won ; Choi, Hark-Sun ; Lew, Jae-Moon ; Kim, Jin-Ha ;
Journal of Ocean Engineering and Technology, volume 19, issue 3, 2005, Pages 11~17
The effect of frequency and amplitude of the OWC (Oscillating Water Column) motion on the nonlinear reaction forces in an air duct are studied experimentally. Experimental owe model is idealized as a simple circular cylinder with an orifice type air duct located at the middle oj the top rid. Reaction forces due to forced heave oscillation are measured and analyzed. By subtracting the effect of inertia forces and restoring forces, pneumatic damping force and added spring force are deduced. The effects of the frequency and amplitude of the heave motion are discussed. Also, the effects of solidity of the duct on the reaction forces are discussed.
Numerical Simulation of Fully Nonlinear Free-Surface Flow around Seawall with Slope
Park, Jong-Chun ; Park, Dong-In ; Lee, Sang-Beom ; Hong, Gi-Yong ; Sun, Sung-Bu ;
Journal of Ocean Engineering and Technology, volume 19, issue 3, 2005, Pages 18~24
Wave overtopping is one of the most important processes for the design of seawalls. The term "wave overtopping" is used here to refer to the processes where waves hit a sloping structure run up the slope and, if the crest level of the slope is lower than the highest run up level, overtop the structure. Wave overtopping is dependent on the processes associated with breaking wave. A numerical model based on Navier-Stokes equation and the Marker-density function for predicting wave overtopping of coastal structures is developed in this paper. In order to evaluate the present model, two simulations are tested. One is overflow without waves at vertical seawall, and the other is wave overtopping at sloping seawalls.
An Analysis of Rolling Performance for a Barge-Type FPSO
Choi, Yoon-Rak ; Kim, Jin-Ha ; Kim, Young-Su ;
Journal of Ocean Engineering and Technology, volume 19, issue 3, 2005, Pages 25~30
To predict rolling performance for a barge-type FPSO, the evaluation of correct nonlinear roll damping is critical. The square section of FPSO causes a considerable viscous damping effect. Free roll decay tests were carried out to estimate nonlinear roll damping for a barge-type FPSO, under three different conditions. The roll motion RAO was deduced from model tests in the wave condition of the wideband spectrum. In numerical calculation, the quadratic damping was considered as equivalent linear damping, using the results of free roll decay test. Tested roll performance in the JONSWAP wave spectrum was compared with numerical results. These two results shaw good agreement, in spite of the proximity of peak wave period and roll natural period.
A Numerical Analysis for the Dynamic Behavior of the Umbilical Cable of a Deep-sea Unmanned Underwater Vehicle
Kwon, Do-Young ; Park, Han-Il ; Jung, Dong-Ho ;
Journal of Ocean Engineering and Technology, volume 19, issue 3, 2005, Pages 31~38
Ocean developments gradually move to deep-sea in the 21 century. A deep-sea unmanned underwater vehicle is one of important tools for ocean resource survey. A marine cable plays an important role for the safe operation and signal transmission of a deep-sea unmanned underwater vehicle. The umbilical cable of a deep-sea unmanned underwater vehicle is excited by surface vessel motion and shows non-linear dynamic behaviors. A numerical method is necessary for analysing the dynamic behavior of a marine cable. In this study, a numerical program is established based on a finite difference method. The program is appled to 6000m long cable for a deep-sea unmanned underwater vehicle and shows good reasonable results.
A Research on Dynamic Tension Response of Model Mooring Chain by Forced Oscillation Test
Cho, Seok-Kyu ; Hong, Sa-Young ; Hong, Sup ; Kim, Hyun-Joe ;
Journal of Ocean Engineering and Technology, volume 19, issue 3, 2005, Pages 39~46
A series of forced oscillation tests on a model mooring chain was carried out to investigate dynamic tension characteristics. The model test was conducted at two different water depths to gather basic data for a 'truncated mooring test' and 'hybrid mooring test'. The truncated and hybrid mooring tests are important for overcoming the limitation of water depth that existed in previous model tests. The resultant tension RAO provides a good possibility of approximation of dynamic tension by equivalent weight adjustment for different water depths. Because the hybrid mooring test is an adequate combination of model test and simulation, an accurate simulation model for the mooring system is essential. The simulation results show good agreement with model test results
Salt and Sand Transport from Aral Sea Basin
Lee, Kwi-Joo ; Shugan, Igor ; Park, Na-Ra ; Begmatov, A. ; Mamatova, N.T. ; Lee, Chung-Hwan ;
Journal of Ocean Engineering and Technology, volume 19, issue 3, 2005, Pages 47~53
Model for dust and salt transportation from the dried bottom of the Aral Sea is suggested. Theoretical analysis is based on the turbulent diffusion equation for the averaged function of passive impurity concentration. One-layer model of the atmospheric boundary layer is assumed. Impurity precipitation rates are calculated as the functions of the particle size and the distance source of particles. Analytical solutions for the point and two-dimensional sources of impurities are found. Model calculations for salt and sand transport from the Aral Sea basin are made on the basis of 2D source model with a constant intensity.
Fatigue Behavior of Large Scale Tubular Joint for API 2W Gr. 50 Steel
Im, Sung-Woo ; Chang, In-Hwa ; Jo, Chul-Hee ; Park, Kwan-Kyu ;
Journal of Ocean Engineering and Technology, volume 19, issue 3, 2005, Pages 54~58
Large-scale model tests of welded tubular K-joints were carried out to observe the fatigue behavior of API 2W Gr.50 steel produced by POSCO. The fatigue crack behaviors for various loading conditions were measured and investigated around the critical joint sections. The experimental results have been verified with numerical approaches and were also compared with the IIW, DnV RP-C203 and API RP 2A-WSD design curves. The hot-spot stress method was applied in the study. The SCF factor for tubular K-joint was also obtaine.
A Optimization of Butterfly Valve using the Characteristic Function
Park, Young-Chul ; Choi, Jong-Sub ; Kang, Jin ;
Journal of Ocean Engineering and Technology, volume 19, issue 3, 2005, Pages 59~65
In today's industry, the butterfly valve has been used to control a flow effectively. However, it is difficult to have the existing structural optimization using field analysis from CFD to structure analysis when the structure is influenced by fluid. Therefore, an initial model of this study is to evaluate the stability of the valve using FEM and CFD. And, it selected variable using initial analysis results. Also, it accomplished the shape optimization design using the orthogonal arrangement and characteristic function. Research result, a few experiments showed the optimal results of there dimensional structures to be multi-objective.
An Anti-Sway Control System Design Based on Simultaneous Optimization Design Approach
Kim, Young-Bok ; Moon, Duk-Hong ; Yang, Joo-Ho ; Chae, Gyu-Hoon ;
Journal of Ocean Engineering and Technology, volume 19, issue 3, 2005, Pages 66~73
The sway motion control problem of a container hanging on the trolley is considered in this paper. In the container crane control problem, the main issue involves suppressing the residual swing motion of the container at the end of acceleration, during deceleration, or for an unexpected disturbance input. For this problem, in general, many trolley motion control strategies are introduced and applied. In this paper, we introduce and synthesize a swing motion control system, in which a small auxiliary mass is installed on the spreader. In this control system, the actuator reacting against the auxiliary mass applies inertial control forces to the container to reduce the swing motion in the desired manner. In many studies, the controllers used to suppress the vibration have been synthesized for the given mathematical model of plants. In many cases, the designers have not been able to utilize the degree of freedom to adjust the structural parameters for the control object. To overcome this problem, so called "Structure/Control Simultaneous Method" is used. From this, in this paper the simultaneous design method is used to achieve optimal system performance. And the experimental result shows that the proposed control strategy is useful, to the case of that the controlled system is exposed to the uncertainties and, robust to disturbances like wind.