• Journal of the Society of Naval Architects of Korea
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• v.47 no.1
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• pp.38-46
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• 2010

This study aims at investigating the effect of the baffle height on the liquid sloshing in the three-dimensional (3D) rectangular tank. In order to simulate the 3D incompressible viscous two-phase flow in the 3D tank with partially filled liquid, the present study has adopted the volume of fluid (VOF) method based on the finite-volume method which has been well verified by comparing with the results of the relevant previous researches. The ratio of the baffle height ($h_B$) to filling level (h) has been changed in the range of $0{\leq}h_B/h{\leq}1.2$ to observe the effect on the impact loads on the side wall and free surface behavior. Generally, as baffle height increases, the impact pressure on the wall decreases and the deformation of free surface becomes weaker. However it seemed that a critical ratio of the baffle height existed to reveal the lowest impact pressure on the wall. Consequently, $h_B/h=0.8$ among $h_B/hs$ considered in the study showed the lowest impact pressure.

• Journal of the Korean Mathematical Society
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• v.44 no.3
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• pp.627-645
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• 2007

We investigate the eigenvalues of the semi-circulant preconditioned matrix for the finite difference scheme corresponding to the second-order elliptic operator with the variable coefficients given by $L_vu\;:=-{\Delta}u+a(x,\;y)u_x+b(x,\;y)u_y+d(x,\;y)u$, where a and b are continuously differentiable functions and d is a positive bounded function. The semi-circulant preconditioning operator $L_cu$ is constructed by using the leading term of $L_vu$ plus the constant reaction term such that $L_cu\;:=-{\Delta}u+d_cu$. Using the field of values arguments, we show that the eigenvalues of the preconditioned matrix are clustered at some number. Some numerical evidences are also provided.

• Journal of applied mathematics & informatics
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• v.25 no.1_2
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• pp.505-511
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• 2007

Recently, the equivalent relations between a symmetric dual problem and a matrix game B(x, y) were given in [6: D.S. Kim and K. Noh, J. Math. Anal. Appl. 298(2004), 1-13]. Using more simpler form of B(x, y) than one in [6], we establish the equivalence relations between a symmetric dual problem and a matrix game, and then give a numerical example illustrating our equivalence results.

• Journal of applied mathematics & informatics
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• v.1 no.1
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• pp.1-12
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• 1994

We consider a single channel CSMA/CD system with D homogeneous stations and impeded buffer of infinite size. We find a sufficient condition for the model to be stable under the threshold control policy and derive the limiting distri-bution of the number of messages in the system at the moment of service completion. We also derive the limiting distributing of the number of messages in the system size at arbitrary time by using Markov regenerative processes. Some numerical examples and special cases are also treated.

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.663-664
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• 2005

• Journal of the Korean Geosynthetics Society
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• v.4 no.2
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• pp.11-18
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• 2005

A pilot scale filed model test and 2-D numerical analysis was conducted to evaluate the effectiveness of constructing a geogrid-reinforced and pile-supported embankment system over soft ground to reduce differential settlement, and the results are presented hearin. Three-by-three pile groups with varying the space between pile were driven into a layer of soft marine clay and a layer of geogrid was used as reinforcement over each pile group. 2-D numerical analysis has been conducted by using the FLAC-2D(Fast Lagrangian Analysis of Continua) program for same condition of field model test. The settlement, vertical stress, and strain of geogrid due to the construction of embankment were measured at various locations. Based on the field model test and numerical analysis results, pile reinforcement generated the soil arching at the midspan of pile cap and the geogrid reinforcement helps reduce the differential settlement of the soft ground by tensile strength of geogrid. Also for $D/b{\geq}6.0$, the effectiveness of geogrid reinforcement in reducing settlement is negligible.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1B
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• pp.89-100
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• 2010

The performance evaluation of a conventional Wave Resonator at the entrance of harbors against solitary wave has been performed using 3D numerical wave flume. A wave resonator has been designed for the attenuation of the transmitted wave energy by trapping the short periodic incident waves only. In this study, however, the controlled performance of the wave resonator by its various widths has been numerically investigated for solitary waves. Source distribution method based on the Green function and the 3D one-field Model for immiscible TWO-Phase flows (TWOPM-3D) using 3D numerical wave flume were used for the short-periodic waves and the solitary waves, respectively, and these models were verified through the comparisons with the previous experimental and numerical results by other researchers. It was confirmed that the wave resonator is effective enough to control the solitary waves as well as the periodic waves when it compares with the case of no resonance system. Further, it was found that there is the optimal width of a wave resonator to attenuate the target solitary waves.

• Advances in Computational Design
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• v.1 no.3
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• pp.253-264
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• 2016

Based on the variation of strain along the cross section, any region in a structural member can be classified into two regions namely, Bernoulli's region (B-region) and Disturbed region (D-region). Since the variation of strain along the cross section for a B-region is linear, well-developed theories are available for their analysis and design. On the other hand, the design of D-region is carried out based on thumb rules and past experience due to the presence of nonlinear strain distribution. Strut-and-Tie method is a novel approach that can be used for the analysis and design of both B-region as well as D-region with equal importance. The strut efficiency factor (${\beta}_s$) is needed for the design and analysis of concrete members using Strut and Tie method. In this paper, equations for finding ${\beta}_s$ for bottle shaped struts in concrete deep beams (a D-region) with and without steel fibres are developed. The effects of transverse reinforcement on ${\beta}_s$ are also considered. Numerical studies using commercially available finite element software along with limited amount of experimental studies were used to find ${\beta}_s$.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.5
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• pp.70-75
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• 2007

A dual-frequency dual-polarization (DFDP) antenna with high isolation between two ports by embedding $2{\times}1$ mushroom-like electromagnetic bandgap (EBG) cells is proposed. The equivalent circuit of a suspended microstrip line over $2{\times}1$ EBG cells is introduced. The numerical analysis from the equivalent circuit and measured results show that the microstrip line with embedded EBG cells has a distinctive and sharp rejection band and provides near 0 dB insertion loss outside the rejection band. By embedding the EBG cells under feedlines of a conventional DFDP antenna, the isolation between two ports of the antenna is enhanced more than 20 dB, as compared to that of a conventional DFDP antenna. The proposed DFDP antenna is fabricated and measured. The simulated and measured results show a good agreement. The measured polarization purity and gain of the antenna are 25 dB and 5.77 dBi at lower band, and 35 dB and 7.13 dBi at higher band, respectively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4B
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• pp.369-376
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• 2011

A three and two dimensional (3D and 2D) numerical models were established to study the storm surge induced by Typoon Maemi in Masan and Pusan Ports. The typhoon landed on the southern coast of Korean Peninsula at 21:00, September 12, 2003 with a central pressure of 950 hPa. The observed maximum storm surge in Masan Port was 230 cm, and the computed peak storm surge using the 3D and the 2D models were 238 cm and 208 cm, respectively. The observed maximum storm surge in Pusan Port was 89 cm, and the peak storm surge of the 3D and the 2D models were 91 cm and 79 cm, respectively. The hindcasted storm surge using 3D model was in good agreement with the observed data, and the 3D model at peak time was more accurate than the 2D. The storm-induced currents were computed using the 3D model. The currents in the surface layer of Masan Bay went into the inner bay with 30~60 cm/sec, while the currents in the bottom layer flowed out with 20~40 cm/sec.