• Journal of the Korean Association of Geographic Information Studies
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• v.5 no.3
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• pp.55-67
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• 2002

Various researches and practices on asset management and asset-based mapping have been done with regard to engineering, industry, business and stocks marketing areas. Their notions and concepts are differently interpreted in response to different requirements. There are considerable research outcomes of management, operation and maintenance for physical, natural and digital assets. However, existing concept of asset management might have limitations to deal with diverse tangible or intangible assets at the individual/household/community level. In this paper, a conceptual framework of Hexad asset model is designed to explicate increase, decrease and other changes of assets flows as a geometric pathway. Particularly, consideration of lands and housing as important physical and natural assets to escape poverty not only leads to creation of an excellent 3D digital asset management, but also reaches to a new approach to asset-based mapping for a poverty information management and system.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.3
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• pp.501-508
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• 1987

Experimental studies of particle (TiO$\_$2/) deposition from the laminar hot gas particle flow (about 1565K) onto the cold wall surface (about 1215K-1530K) were carried out by the 'real time' laser light reflectivity method (LLRM) and the photographs of scanning electron microscope(SEM). The LLRM was used for the measurement of thermophoretic deposition rates of small particles (d$\_$p/<3.mu.m), and the photographs of SEM were used for determining what factors control the collection of particles having diameters ranging from 0.2 to 30 microns. Two phenomena are primarily responsible for transport of the particles across the laminar boundary layers and deposition: (1) particle thermophoresis (i.e. particles migration down a temperature gradient), and (2) particle inertial impaction, the former effect being especially larger factor of the particle deposition in its size over the range of 0.2 to 1 microns. And also, this study indicates that thermophoresis can be important for particles as large as 15 microns. Beyond d$\_$p/=16.mu.m, this effect diminishes and the inertial impaction is taken into account as a dominant mechanism of particle deposition. The results of present experiments found to be in close agreement with existing theories.

• Journal of Korean Society on Water Environment
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• v.34 no.4
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• pp.363-374
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• 2018

The Han River serves as an important water resource for the city of Seoul, Korea and in the neighboring metropolitan areas. From the Paldang dam to the Jamsil submerged weir, the 4 water intake stations that are located for the Seoul metropolitan population were under review in this study. Therefore the water quality management in this section is very important to monitor, analyze and review to rule out any safety concerns. In this study, a 3-D hydrodynamic model, EFDC (Environmental Fluid Dynamics Code), was applied to the downstream of the Paldang Dam in the Han River, which is about 23 km in length, to determine issues related to water resource management. The 3-D grid was composed of 2,168 horizontal grids and three vertical layers. In this case, the hydrodynamic model was calibrated and verified with an observed average daily water surface elevation, water temperature and flow rate data for 3 years (2013~2015). The developed EFDC model proved to reproduce the hydrodynamics of the Han River well. The composition ratios of the noted incoming flows at the monitored intake stations for 3 years and their flow patterns in the river were analyzed using the validated model. It was found that the flow of the Wangsuk Stream depended on the Paldnag dam discharge, and it was noted that the composition ratios of the stream at the intake stations changed accordingly. In a word, the Wangsuk Stream moved mainly along the right bank of the Han River under the condition of a normal dam flow. As can be seen, when the dam discharge rate was low, the incidence of lateral mixing was often seen. The scenario analyses were also conducted to predict the transport of conservative pollutants as in the case of a chemical spill accident. Generally speaking, when scenarios were applied, the arrival time and concentration of pollutants at each intake station was thus predicted.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.79-85
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• 2006

Radiative heat transfer is very important in many combustion systems since they are operated in high temperature. Fluid flows in most of the combustion systems are turbulent to promote fast mixing of the hydrocarbon fuel and oxidant. Major combustion products are $CO_2$ and $H_2O$. The turbulent flow is modeled by using the standard ${\kappa}-{\epsilon}$ model and the radiation transfer is modeled by using the discrete ordinates method where the radiative gas properties are calculated by using the weighted sum of gray gases model with a gray gas regrouping(WSGGM-RG). Effect of the radiation on the combustion characteristics in a three-dimensional rectangular enclosure is studied by changing the equivalence ratio. Results show that the radiation plays a significant role on the heat transfer in the combustion systems by resulting in a temperature drop of 16% as compared to that obtained without radiation. The equivalence ratio also affects the combustion by different contribution of the radiative transfer with different gas compositions.

• Journal of Korea Multimedia Society
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• v.19 no.2
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• pp.224-232
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• 2016

The methodology to visualize the shape of blood vessel and its blood flow have been attracting as a very interesting problem to forecast and examinate a disease in thrombus precursor protein. May previous visualization researches have been appeared for designing the blood vessel and also modeling the blood flow using a doppler imaging technique which is one of nondestructive testing techniques. General visualization methods are to depict the blood flow obtained from doppler effects with fragmentary stream lines and also visualize the blood flow model using volume rendering. However, these visualizeation techniques have the disadvantage which a set of small line segments does not give the overall observation of blood flows. Therefore, we propose a visualization system which reconstruct the continuity of the blood flow obtained from doppler effects and also visualize the blood flow with the vector field of blood particles. This system will use doppler phase difference from medical equipments such as OCT with low penetration and reconstruct the blood flow by the curvature estimation from vector field of each blood particle.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.3
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• pp.17-24
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• 2016

The reacting flows of gaseous hydrogen/liquid oxygen 2D coaxial shear injector with varying recess length are numerically analyzed. The standard ${\kappa}-e$ model and laminar flamelet model are adopted for the steady turbulent combustion with the ideal and real gas equations. As the recess length increases, the recirculating region in the combustion chamber expands and the vorticity is intensified. Also, the variations of temperature, products, and pressure are strongly related to the recess length. The results show that an efficient combustor can be obtained by the introduction of the recessed injector.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.516-520
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• 2009

This study describes aerodynamic characteristics for the HAWT (Horizontal Axis Wind Turbine) rotor blade using general CFD(Computational Fluid Dynamics) code. The boundary conditions for analysis are validated with the experimental result by the NREL (National Renewable Energy Laboratory)/NASA Ames wind tunnel test for S809 airfoil. In the case of wind turbine rotor blade, complex phenomena are appeared such as flow separation and re-attachment. Those are handled by using a commercial flow analysis tool. The 2-equation k-$\omega$ SST turbulence model and transition model appear to be well suited for the prediction. The 3-dimensional phenomena in the HAWT rotor blade is simulated by a commercial 3-D aerodynamic analysis tool. Tip vortex geometry and Radial direction flows along the blade are checked by the analysis.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.6
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• pp.702-708
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• 2006

This study shows the experimental characteristics of the double pipe inserted liquid pipe with small diameter in the gas pipe with large diameter for circulating of a liquid of high temperature, pressure and a gas of low temperature, pressure at the same time. So the functions of pipe and pipe's expansion and heat transfer are presented simultaneously. In the result, the temperature of gas refrigerant at the inlet of compressor increased about $5^{\circ}C$ by the heat transfer with liquid refrigerant in case of the double pipe. And liquid gas refrigerant which the temperature at the inlet of evaporator decreased about $3^{\circ}C$ comparing with the existing type flows into an evaporator COP of the double pipe increased about $7{\sim}10%$ comparing with that of the conventional pipe. And the noise of the double pipe at capillary tube is less than that of the conventional type about 3dB. Consequently. it is convinced the superiority of the double pipe in the heat loss and soundproofing aspect.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1370-1376
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• 2015

Generally, an autotransformer(AT) feeding system consists of double tracks, up and down, with the trolley wire and feeder wire of the up and down tracks connected in the sectioning post(SP). Consequently, load current or fault current flows on two tracks based on catenary impedance characteristics, making it difficult to estimate catenary impedance accurately. This paper presents a technique for the estimation of catenary impedance using boosting current compensation based on the current division characteristics of an AT feeding system to improve the operation performance of impedance relay. To verify the technique, we model an AT feeding system through a power analysis program (PSCAD/EMTDC) and simulate various operation and fault conditions. Through the simulation, we confirmed that the proposed technique has estimated catenary impedance with a similar degree of accuracy to the actual catenary impedance

• Journal of computational fluids engineering
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• v.3 no.2
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• pp.39-51
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• 1998

This paper describes the analysis of flow field around an automobile. The governing equations of the 3-D unsteady incompressible Navier-Stokes equations are solved by the iterative time marching scheme. The Chimera grid technique has been applied to efficiently simulate the flow around the side-view mirror. To validate the capability of simulating the flow around a ground vehicle, the flows around the Ahmed body with 12.5$^{\circ}$ and 30$^{\circ}$ of slant angles are simulated and good agreements with experiment and other numerical results are achieved. To validate Chimera grid technique, the flow field around a cylinder was also calculated. The computed results are also well agreed with other numerical results and experiment. After code validations, the flow phenomena around the ground vehicle are evidently shown. The flow around the side-view mirror is also well simulated using the Chimera grid technique.