• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1999.10a
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• pp.253-261
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• 1999

It is essential for port planning, coastal zone management and environmental impact study to analyze the variation of current and water quality due to the development of water area and discharged water from the estuary barrage and basin, etc. Mokpo sea area has downstream from a long river and two large basins, the Yongsan river and Yongam-Kumho basins, discharging much of water through water gates for the purpose of flood and prohibition of salt intrusion to the inland fresh water area. In this study, the numerical calculation were carried out for the analysis of diffusion characteristics due to discharging operation, adopting the results of tidal current simulation. ADI method is applied to the governing equation for the movement of sea water and diffusion and 6-point method to the advection terms of diffusion equation. As the results of this study, it is known that the discharging operation causes increasing and/or decreasing of current velocity and enlarging and/or depressing of pollutant diffusion limits depending on the distance from the discharging gates and the modes of discharging operation. To utilize these result, the linked gate operation and the method increasing exchange of sea water must be considered.

• Environmental Engineering Research
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• v.23 no.4
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• pp.442-448
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• 2018

This paper presents the numerical simulation of advection-diffusion mechanism of BOD concentration which was used as an indicator of waste only in one flow-direction of waste stabilization ponds (1-dimension (1-D)). This model was represented in partial differential equation order 2. The purpose of this paper was to determine the simulation of the model 1-D of wastewater transport phenomena based advection-diffusion mechanism and did validate the model. Numerical methods which was used for the solution of this model is finite difference method with Forward Time Central Space scheme. The simulation results which was obtained would be compared with field observation data as a validation model. Collection of field data was carried out in the Wastewater Treatment Plant Sewon, Bantul, D.I. Yogyakarta. The results of numerical simulations were indicate that the advection-diffusion mechanism takes place continuously over time. Then validation of the model was state that there was a difference between the calculation results with the field data, with a correlation value of 0.998.

• Bulletin of the Korean Chemical Society
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• v.28 no.10
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• pp.1697-1704
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• 2007

We present results for transport properties of diatomic fluids by isothermal-isobaric (NpT) equilibrium molecular dynamics (EMD) simulations using Green-Kubo and Einstein formulas. As the molecular elongation of diatomic molecules increases from the spherical monatomic molecule, the diffusion coefficient increases, indicating that longish shape molecules diffuse more than spherical molecules, and the rotational diffusion coefficients are almost the same in the statistical error since random rotation decreases. The calculated translational viscosity decreases with the molecular elongation of diatomic molecule within statistical error bar, while the rotational viscosity increases. The total thermal conductivity decreases as the molecular elongation increases. This result of thermal conductivity for diatomic molecules by EMD simulations is again inconsistent with the earlier results of those by non-equilibrium molecular dynamics (NEMD) simulations even though the missing terms related to rotational degree of freedom into the Green-Kubo and Einstein formulas with regard to the calculation of thermal conductivity for molecular fluids are included.

• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.1
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• pp.51-58
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• 1998

The opening of an event in a given geographical area may be defined as an innovation. Visitors to the event adopt the innovation; therefore, their visitation patterns since the opening can be regarded as a diffusion process. Bass' model of diffusion process was applied to analyzing weekly visitation of Kwang-ju Viennale. Parameters of the Bass' model were estimated by regression analysis, and then reviewed in terms of applicability. Actual estimation of event visitation was implemented by calculation of the three parameters of the model based on the actual data. After comparing estimated value with actual value, it was concluded that Bass' model is applicable to estimating event visitation as far as it is the only prediction method available at this point.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.3
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• pp.1-7
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• 2015

Korea's electricity supply and demand policy has focusing on electricity demand side management instead of the expanding supply and a lot of effort for LED(Light Emitting Diode) at the time. This paper calculated the optimal subsidy for LED spread. For this purpose, it analyzed the impact on spread of the lighting appliances each subsidy level from BDM(Bass Diffusion Model) and predicted the number of lighting appliances according to subsidy level in the future. The case study is calculated susidy for satisfaction of LED target using the suggested model in the future and verified availability.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.25-28
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• 2008

This study investigates the effect of geometrical shape of concert halls, with variation in the shape and location of diffusers. The acoustical characteristics both in the audience area and on the stage 1:50 scale models of shoebox and fan-shaped halls. It was found that the front side walls affect sound diffusion. The 1:50 scale model based on the Boston Symphony Hall was used for monaural impulse response measurements for calculation of RT, EDT, C80, G and ST1. In addition, calculating the numbers and amplitudes of reflection rays were applied to quantify diffusion phenomena.

• Journal of the Korean Society for Heat Treatment
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• v.14 no.5
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• pp.282-285
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• 2001

Based on the mass balance of anion and cation fluxes, the parabolic rate constant ($K_p$) of oxide grown during the high-temperature oxidation of metal is theoretically calculated. It is assumed that the diffusion of oxygen anion and metal cation through oxide scale obeys the Fick's 1st law, the growth of oxide is controlled by the diffusion of ions, electrical potential gradient as driving force for diffusion of ions is ignored, and oxidation occurs within an existing oxide layer. Then, the parabolic rate constant can be expressed by $K_p=[2{\rho}_{MmOn}{M^2}_{MmOn}(mD_oC_o{^e}+nD_MC_M{^e})/nm]$.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.6
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• pp.929-935
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• 1986

In this paper, we describe the physical modelling and numerical aspects of a program called PRECISE(Program for Efficient Calculation of Impurity Profile in Semiconductor by Elimination) which calcualtes a two-dimensional impurity profile in silicon due to diffusion and ion implantation steps. The PRECISE enables rapid prediction of the two-dimensional impurity profile near the mask edge-or the bird's beak during the local oxidation process. This has been developed by modifying the existing one-dimentional simulator, DIFSIM(DIFfusion SIMulator to include models for arsenic diffusion and emitter dip effect which were found out to agree fairly well with the xperimental data.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.63-64
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• 2004

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.4
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• pp.381-383
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• 1999

First topic of this paper aims to clarify how oxygen and heat transfer in silicon melt under cusp-shaped magnetic fields. We obtained asymmetric temperature distribution by using time dependent and three-dimensional calculation. Second topic is study on molecular dynamics simulation, which was carried out to estimate diffusion constants of oxygen in silicon melt.