• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.5
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• pp.415-423
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• 2015

In this study, we present a grid refinement model in the lattice Boltzmann method (LBM) for two-dimensional incompressible fluid flow. That is, the model combines the desirable features of the lattice Boltzmann method and stream function-vorticity formulations. In order to obtain an accurate result, very fine grid (or lattice) is required near the solid boundary. Therefore, the grid refinement model is used in the lattice Boltzmann method for stream function-vorticity formulation. This approach is more efficient in that it can obtain the same accurate solution as that in single-block approach even if few lattices are used for computation. In order to validate the grid refinement approach for the stream function-vorticity formulation, the numerical simulations of lid-driven cavity flows were performed and good results were obtained.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.60-66
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• 2010

Mesh grounding electrodes in Korea and abroad are designed as lattice-shaped equidistance grounding grids. In case of a lattice-shaped grounding Grid, however, there is a problem of higher touch voltage at the corner of the grid relative to the center. To overcome this problem, we used oblique-shaped equidistance grounding grid to reduce the area of the corner where mesh voltage occurs. As a result the mesh voltage was reduced. Therefore, this paper suggests the use of oblique-shaped grounding grid instead of the existing lattice-shaped ones. It applied the same grounding design dimensions for both lattice-shaped and oblique-shaped grounding grids, compared and analyzed mesh voltage, GPR, ground resistance, total length of grounding conductor, verified that oblique-shaped grounding grid is superior to the lattice-shaped.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.1
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• pp.74-96
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• 2023

At present, the smart grid has become one of the indispensable infrastructures in people's lives. As a commonly used communication method, wireless communication is gradually, being widely used in smart grid systems due to its convenient deployment and wide range of serious challenges to security. For the insecurity of the schemes based on large integer factorization and discrete logarithm problem in the quantum environment, an identity-based key management scheme for smart grid over lattice is proposed. To assure the communication security, through constructing intra-cluster and inter-cluster multi-hop routing secure mechanism. The time parameter and identity information are introduced in the relying phase. Through using the symmetric cryptography algorithm to encrypt improve communication efficiency. Through output the authentication information with probability, the protocol makes the private key of the certification body no relation with the distribution of authentication information. Theoretic studies and figures show that the efficiency of keys can be authenticated, so the number of attacks, including masquerade, reply and message manipulation attacks can be resisted. The new scheme can not only increase the security, but also decrease the communication energy consumption.

• 한국전산유체공학회:학술대회논문집
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• 2006.05a
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• pp.81-82
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• 2006

• Journal of Ocean Engineering and Technology
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• v.20 no.1 s.68
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• pp.48-54
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• 2006

In this paper, flowfield and acoustic-field around moving bodies are simulated by the Arbitrary Lagrangian Eulerian (ALE) formulation in the finite difference lattice Boltzmann method. Some effects are checked by comparing flaw about a square cylinder in ALE formulation and that in the fixed coordinates, and both agree very well. Matching procedure between the moving grid and fixed grid is also considered. The applied method in which the both grids are connected through buffer region is shown to be superior to moving overlapped grid. Dipole-like emissions of sound wave from harmonically vibrating bodies in two- and three-dimensional cases are simulated.

• Journal of Korean Association for Spatial Structures
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• v.2 no.4 s.6
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• pp.45-52
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• 2002

Research about spherical shells been applying most usually is achieved by many investigators already and generalized equation has been derived. But, existent research is limited in case that spherical shell's roof rigidity is isotropy or orthotropy, and research that consider periodicity of rigidity-distribution that can happen by doing spherical shell's roof system by lattice system is not gone entirely. The purpose of this paper is applying Galerkin method to spherical shell that model periodicity of roof rigidity distribution that appear by roof lattice form of large space structure and develop structural analysis program that formularize. Rigidity-model of this research selects that of spherical shell which has 2-way grid. In this paper, buckling-strength and deformation distribution of isotopic spherical shell and 2-way grid spherical shell obtained by developed program could confirm the reliability by comparison with result of existent research.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.54-57
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• 2011

In this paper we present an algorithm about how to simulate two dimensional dam breaking with lattice Boltzmann method (LBM). LBM considers a typical volume element of fluid to be composed of a collection of particles that represented by a particle velocity distribution function for each fluid component at each grid point. We use the modified Lattice Boltzmann Method for incompressible fluid. This paper will represent detailed information on single phase flow which considers only the water instead of both air and water. Interface treatment and conservation of mass are the most important things in simulating free surface where the Interface is treated by mass exchange with the water region. We consider the surface tension on the interface and also bounce back boundary condition for the treatment of solid obstacles. We will compare the results of the simulation with some methods and experimental results.

• Journal of computational fluids engineering
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• v.19 no.2
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• pp.79-85
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• 2014

An air-water free surface flow simulation by using the Lattice Boltzmann Method(LBM) has not been studied a lot compared with the done by the Navier-Stoke equation. This paper shows the LBM is as one of the application tools for the free surface movement over an obstacle. The Mezo scaled application tool has been developed with two dimensional and nine discretized velocity direction using conventional lattice Bhatnagar-Gross-Krook model. Boundary conditions of a halfway-based for solid wall and a kinematic-based for interface are adopted. A validation case with a trapezoidal shape bump to make a comparison between freesurface movements from computational results and experimental ones was described with grid size dependency.

• Journal of architectural history
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• v.10 no.1 s.25
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• pp.9-23
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• 2001

This study is for the Kyungduk-Dan(as a altar of Milsung-Daegun) and The Manun-Jae the characteristics(lay out and planning, window patterns, structure, materials) of the the Korean traditional house during the modern era. Before Manun-Jae was used for the house. The Kyungduck-Dan was constructed in August according to the Lunar Calender in 1927. The Manun-Jae(house for Ki-hun Kang, millionaire ) was completed in 1924. Modern Architectures brought to Korea with the bricks, the tiles, the flash doors, the plate grasses, the brass hardwares. These architectural material was used in positive. During the construction of Manun-Jae in 1924, it happened the architectural exchage among a korean, a chinese and a japanese constructor. Though using the air exhaust valve at the kitchen of Ukyung-Kak( old Anchae), it could be assume that the modern convenience and the improvement of residential environments was considered at that period during the construction of Manun-Jae. That construction was elected with the brick($222mm{\times}106mm{\times}50mm$), the chinese colored tile and plate glass such a modem materials. The new shape of the korean lattice window and the wooden flash-door with glass was used. In Ukyung-Kak, the Chan-Maru(service space) and the kitchen such as a service space or concise utility zone was organically connected. Especially, considered the domesitic activity and circulation, the western kitchen sink and the Chan-Maru(service space) was rationally placed. At the Manun-Jae and the Kyungduck-Dan, the architectural characteristic is that the new shape of windows was used. The lattice window at the Ondol room of Ukyung-Kak, was rgadually added the plate glass and the wood plate. The lattice window with the grid shape at kitchen of that building was adapted japanese grid lattice window in korea at that period. It is the sample that korean traditional house was typically influenced from the japanese resident culture. The Manun-Jae and the Kyungduck-Dan as the modern house kept the form of korean traditional architecture, and was partially adapted a modern characteristic space and modern architectural materials. During the japanese occupancy, these residence can be showed the transition in formally.

• Journal of computational fluids engineering
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• v.16 no.4
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• pp.7-13
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• 2011

A comparative analysis of thermal models in the lattice Boltzmann method(LBM) for the simulation of laminar natural convection in a square cavity is presented. A HYBRID method, in which the thermal equation is solved by the Navier-Stokes equation method while the mass and momentum conservation are resolved by the lattice Boltzmann method, is introduced and its merits are explained. All the governing equations are discretized on a cell-centered, non-uniform grid using the finite-volume method. The convection terms are treated by a second-order central-difference scheme with a deferred correction method to ensure stability of the solutions. The HYBRID method and the double-population method are applied to the simulation of natural convection in a square cavity and the predicted results are compared with the benchmark solutions given in the literatures. The predicted results are also compared with those by the conventional Navier-Stokes equation method. In general, the present HYBRID method is as accurate as the Navier-Stokes equation method and the double-population method. The HYBRID method shows better convergence and stability than the double-population method. These observations indicate that this HYBRID method is an efficient and economic method for the simulation of incompressible fluid flow and heat transfer problem with the LBM.