• Journal of the Korean Association of Geographic Information Studies
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• v.11 no.4
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• pp.41-50
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• 2008

Intense competition for resources has forced many countries pay attention to their eyes to the ocean. Therefore, the disputes and the conflict over the delimitation of the EEZ and continental shelf will be sharpened. Since 1982 Law of the Sea Convention, Korea has opened the talks with Japan and China to discuss the boundary issues as the adjacent water zone is less than 400 miles between Korea and Japan and Korea and China. This study is to review the important rules and techniques for the delimitation of the maritime boundary which have defined in the Law of the Sea Convention and IHO-51 technical guide and to figure out how to build the maritime delimitation GIS DB to negotiate effectively with the neighboring countries. Definition of the base point and baseline will be the utmost important concept to delimit the ocean boundary. The policy makers and the specialists who prepare for the international negotiation meeting between the countries have to be ready to draw the maritime boundary for our best interest under the Law of the Sea Convention. The negotiation strategies and the principles can be made with the concrete and reliable database relevant to maritime boundary issues. So effective and fast strategic decision for negotiation can only be made based on maritime boundary delimitation GIS DB.

• The Pure and Applied Mathematics
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• v.11 no.1
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• pp.73-88
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• 2004

A punctured torus $\Sigma(1,1)$ is a building block of oriented surfaces. The goal of this paper is to formulate the matrix presentations of elements of the Teichmuller space of a punctured torus. Let $\cal{C}$ be a matrix presentation of the boundary component of $\Sigma(1,1)$.In the level of the matrix group $\mathbb{SL}$($\mathbb2,R$) we shall show that the trace of $\cal{C}$ is always negative.

• Journal of Ocean Engineering and Technology
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• v.3 no.2
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• pp.535-535
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• 1989

• Journal of the Earthquake Engineering Society of Korea
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• v.17 no.6
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• pp.245-255
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• 2013

According to natural frequency of soil, characteristics of earthquake responses of an isolated containment building in nuclear power plants are examined. For this, earthquake response analysis of seismically isolated containment buildings in nuclear power plants is carried out by strictly considering soil-structure interactions. The structure and near-field soil are modeled by the finite element method while far-field soil by consistent transmitting boundary. The equation of motion of a soil-structure interaction system under incident seismic wave is derived. The derived equations of motion are solved to carry out earthquake analysis of a seismically isolated soil-structure system. Generally, the results of this analysis show that seismic isolation significantly reduces the responses of the soil-structure system. However, if the natural frequency of the soil is similar to that of the soil-structure system, the responses of the containment buildings in nuclear power plants rather increases due to interactions in the system.

• Journal of the Korean Institute of Rural Architecture
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• v.22 no.3
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• pp.41-48
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• 2020

The purpose of this research is to manage the physical sectors systematically, needed for the selection and direction of declining areas, such as urban regeneration and revitalization projects, by grading the density of decline indicators of buildings in small and medium cities. In five small and medium-sized cities in Jeollanam-do, the data were divided into three stages according to the density, according to the use, structure, and age of the building. Rating by element of Census Output Area, detailed designation, and management of declining areas in small and medium-sized cities are required, rather than setting the scope of declining areas based on administrative districts. It is also necessary to manage cities through complex and intra-element phasing rather than single elements in defining physical decline. The analysis based on the complex factors and boundary of the Census Output Area is meaningful in order to maintain and manage such cities in a more detailed and precise manner according to such characteristics of each region.

• Wind and Structures
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• v.30 no.6
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• pp.597-616
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• 2020

The blockage effect on the aerodynamic characteristics of tall buildings is a fundamental issue in wind tunnel test but has rarely been addressed. To evaluate the blockage effects on the aerodynamic forces on a square tall building and flow field peripherally, large eddy simulations (LES) were performed on a 3D square cylinder with an aspect ratio of 6:1 under the uniform smooth inflow and turbulent atmospheric boundary layer (ABL) inflow generated by the narrowband synthesis random flow generator (NSRFG). First, a basic case at a blockage ratio (BR) of 0.8% was conducted to validate the adopted numerical methodology. Subsequently, simulations were systematically performed at 6 different BRs. The simulation results were compared in detail to illustrate the differences induced by the blockage, and the mechanism of the blockage effects under turbulent inflow was emphatically analysed. The results reveal that the pressure coefficients, the aerodynamic forces, and the Strouhal number increase monotonically with BRs. Additionally, the increase of BR leads to more coherence of the turbulent structures and the higher intensity of the vortices in the vicinity of the building. Moreover, the blockage effects on the aerodynamic forces and flow field are more significant under smooth inflow than those under turbulent inflow.

• Structural Engineering and Mechanics
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• v.31 no.6
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• pp.679-696
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• 2009

The paper aims at analyzing the stress distribution around an underground opening that is subjected to non-symmetrical surface loading with emphasis on opening shapes with sharp corners and the stress concentrations developed at these locations. The analysis is performed utilizing the BIE method coupled with the Neumann's series. In order to implement this approach, the special recurrent relations for half plane were proven and the modified Shanks transform was incorporated to accelerate the series convergence. To demonstrate the capability of the developed approach, a horseshoe shape opening with sharp corners was investigated and the location and magnitude of the maximum hoop stress was calculated. The dependence of the maximum hoop stress location on the parameters of the surface loading (degree of asymmetry, size of loaded area) and of the opening (the opening height) was studied. It was found that the absolute magnitude of the maximum hoop stress (for all possible surface loading locations) is developed at the roof points when the opening height/width ratio is relatively large or when the pressure loading area is relatively narrow (compared to the roof arch radius), and contrarily, when the opening height/width ratio is relatively small or when the surface pressure is applied to a relatively wide area, the absolute magnitude of the maximum hoop stress is developed at the bottom sharp corner points.

• Wind and Structures
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• v.11 no.4
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• pp.323-340
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• 2008

In this paper, the along-wind, across-wind as well as torsional dynamic wind loads on three kinds of lattice tower models are investigated using the base balance technique in a boundary layer wind tunnel. The models were specially designed, and their fundamental frequencies in the directions of the three principal axes are still in the frequency range of the spectra of wind loads on lattice towers. In order to clear contaminations to the spectra of wind loads induced by model resonance, the generalized force spectra of the first mode of the models in along-wind, across-wind and torsional directions were derived based on measured base moments of the models. The RMS generalized force coefficients are also obtained by removing the contributions of model resonance. Finally, the characteristics of the 3-D dynamic wind loads, especially those of the across-wind dynamic loads, on the three kinds of lattice towers are presented and discussed.

• Structural Engineering and Mechanics
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• v.20 no.3
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• pp.313-334
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• 2005

The paper presents a new approach for the analysis of slope stability that is based on the numerical solution of a differential equation, which describes the thrust force distribution within the potential sliding mass. It is based on the evaluation of the thrust force value at the endpoint of the slip line. A coupled approximation of the slip and thrust lines is applied. The model is based on subdivision of the sliding mass into slices that are normal to the slip line and the equilibrium differential equation is obtained as the slice width approaches zero. Opposed to common iterative limit equilibrium procedures the present method is straightforward and gives an estimate of slope stability at the value of the safety factor prescribed in advance by standard requirements. Considering the location of the thrust line within the soil mass above the trial slip line eliminates the possible development of a tensile thrust force in the stable and critical states of the slope. The location of the upper boundary point of the thrust line is determined by the equilibrium of the upper triangular slice. The method can be applied to any smooth shape of a slip line, i.e., to a slip line without break points. An approximation of the slip and thrust lines by quadratic parabolas is used in the numerical examples for a series of slopes.

• Journal of Hydrogen and New Energy
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• v.29 no.4
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• pp.370-377
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• 2018

Ball valve has been widely used in the field of high-pressure gas pipeline as an important component because of its low flow resistance and good leakage performance. The present paper focuses on the flow nature at the downstream of the ball valve used for gas pipelines according to valve opening rates. Steady 3-D RANS equations, SC/Tetra, have been introduced to analyze the flow characteristics inside the ball valve. Numerical boundary conditions at the inlet and outlet of the valve system are imposed by mass flow-rate and pressure, respectively. Velocity distributions obtained by numerical simulation are compared with respect to the valve opening rates of 30, 50, and 70%. Cavity distributions, asymmetry flow velocity and the flow stabilization point at each opening rate are also compared. When the valve opening rates are 30 and 50%, the flow stabilization requires the sufficient length of 10D or more due to the influence of the recirculation flow at the downstream of the valve.