• Journal of Ocean Engineering and Technology
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• v.10 no.1
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• pp.81-91
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• 1996

Numerical study is carried out to make clear the wavemaking phenomena for a planning flat plate. Through the mumerical computations, some schematic wave patterns are compared with experimental results, for example, such as the bow divergent waves, triangle waves, stern divergent saves, stern cross waves. The characteristic distance of waves is found to be more inconsistent as the incidence angle increases. The comparison was mode between computations and experiments for incidence angles of 5, 10 and 15 degrees. However, a numerical difficulty is found around and behined the trailing edges for more than 20 degree.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.135-140
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• 2006

Numerical computations are made to predict wave loads on a vertical cylinder in an extreme wave. To generate the extreme wave, a frequency-focused unidirectional wave is adopted in three-dimensional numerical wave tank. The mathematical formulation is wide in the scope of the potential theory with fully nonlinear free surface conditions. As a numerical method, finite element method based on variational principle is applied. Comparisons between the present numerical results and the previous computation data. show a good agreement.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.630-633
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• 2008

A particle method has been developed for analyzing the motion of 2-D floating body in waves. The particle method is based on the MPS(Moving Particle Semi-implicit) method suggested by Koshizuka et al. (1996), and the flow motion coupled with the motion of floating body can be simulated. The wavemaker and wave absorber are installed at the inflow and outflow boundaries in a computational domain, respectively. The motion characteristics of a floating body is investigated numerically under the various computational conditions.

• Journal of computational fluids engineering
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• v.8 no.1
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• pp.16-22
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• 2003

The present study introduces an architecture for performing efficient numerical analysis by using the Internet and three reconstructing methods of existing numerical analysis codes were presented in order to utilize the architecture. These methods were implemented into a computational fluid dynamics program for solving two-dimensional transient flow problems with free surface. The program was reconstructed with Java technologies and compared with the original one. This study will be a preparation for numerical analysis to participate in web services for engineering.

• The KSFM Journal of Fluid Machinery
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• v.11 no.1
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• pp.46-51
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• 2008

A stability analysis has been made for a newly designed gate of intake tower of reservoir. The analysis is composed of finding the natural frequency of the gate and the frequency induced by water flowing over and through the gate. ANSYS is employed to calculate the natural frequency of the gate and SC/Tetra is utilized for calculating flow field around the gate, which in turn gives the frequency of pressure force fluctuation on the gate. In addition to the safety analysis, the present study presents how the gate selectively intakes a muddy water layer located in the middle depth of reservoir.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.3
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• pp.339-347
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• 2001

Automatic automobile has been studied as the alternative energy system and the production flow automation device recently. But this is dependent on the import production, and its position cannot be controlled free from the fixed path. It is difficult to control the automobile position because of the eccentricity of inertia monent, slip and roughness between wheel and road surface. This problems is solved for the controller to be feedbacked the data of the multi-sensor system consisting of the rotary encoder and electronic compass. The proportional Integrated controller in the modified Ziegler-Nichols method is made up with Hitachi 7034 microprocessor. To the real time control the mechanical, electrical and electronic hardware and software device is produced by myself. The RF data of automobile speed and position is supplied to the remote PC to be displayed the automobile condition. By the experinent of the forward, spin, point path planning, it is known for autombile.

• Journal of Ship and Ocean Technology
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• v.4 no.3
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• pp.21-32
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• 2000

In the present paper, the sloshing flow in the liquid holds of a large tanker is simulated using a numerical method. In the fluid domain, the three-dimensional Navier-Stokes equation with free surface is solved using a finite difference method, and the realistic shapes of multi holds are modeled including the internal members. The time-history of the tank motion is obtained using a time-domain program for ship motion. In order to computer the impulsive pressures on internal structures, a concept of buffer zone is adopted near the tank ceiling during impact occurrence. This study demonstrates that the global fluid motion in the multi liquid holds of ships and FPSO's can be simulated using the numerical method and the corresponding local pressure can be predicted with reasonable accuracy.

• Fisheries and Aquatic Sciences
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• v.1 no.2
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• pp.168-179
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• 1998

Circulation in the Jinhae Bay in the southern sea of Korea is examined using the Princeton Ocean Model (POM) with a free surface in a sigma coordinate, governed by primitive equations. The model well corresponds to the time series of the observed velocities at several layers obtained from a long-term mooring observation. In the residual velocity field of the model, persistent downward flow fields are formed along the central deep regions in the bay, and they are caused by bottom topographic effect. In addition, a comparison between a depth-averaged (2D) model and the POM is given, and a dependance of the results on bottom drag coefficient is also examined.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.1
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• pp.23-30
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• 2004

In the Lagrangian vortex particle method based on the vorticity-velocity formulation for solving the incompressible Navier-Stokes equations, a numerical scheme for calculating pressure fields is presented. Implementation of the numerical method is directly connected with the well-established surface panel methods, just by dealing with the dynamic coupling among vorticity field. Assuming the vorticity and the velocity fields are to be calculated in time domain analysis, the pressure calculation for a complete set of solution at present time step is performed in a similar way to the one used in the Eulerian description. For a validation of the present method, we illustrate the early development of the viscous flow about an impulsive started circular cylinder for Reynolds number 550. The comparative study with the Eulerian finite Volume method provides an extensive understanding and application of the mesh-free Lagrangian vortex methods for numerical simulation of viscous flows around arbitrary bodies of general shape.

• Bulletin of the Society of Naval Architects of Korea
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• v.23 no.2
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• pp.27-32
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• 1986

This paper describes an application of the adaptive finite element computations to a free surface flow problem in a canal. A-posteriori error estimates for the adaptive finite element computations are based on the dual extremum principles. Previously the dual extremum principles were applied to compute the upper and lower bounds of the added mass of two-dimensional cylinders in a canal[1,2]. However, the present method improves the convergence of the computed results by utilizing the local error estimates and by applying the adaptive meshes in the finite element computations. In a test result using triangular elements it is shown that the numerical error in the adaptive finite elements reduces quadratically compared with that in a uniform mesh subdivision.