• Journal of Korean Society for Atmospheric Environment
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• v.28 no.2
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• pp.190-202
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• 2012

Emissions of air pollutants and greenhouse gases (GHGs) by aircraft at the Gimhae International Airport (GIA) were investigated using the Emissions and Dispersion Modeling System (EDMS) version 5.1.3. The number of Landing and Take-Off (LTO) at the GIA for aircraft B737 was dominant, accounting for more than 60% of the total LTOs. For air pollutant emissions, CO was the most dominant pollutant by aircraft, followed by $NO_x$, VOCs, $SO_x$, etc. The emissions of CO, $NO_x$, and VOCs in 2009 (and 2010) at the GIA were 974 (968), 447 (433), 118 (122) ton/yr, respectively. The emissions of GHGs such as $CO_2$, $CH_4$, and $N_2O$ in 2009 (and 2010) were 110,795 (111,114), -0.157 (-0.151), and 1,989 (1,998) ton/yr, respectively. The negative number in $CH_4$ emission represents the consumption of atmospheric $CH_4$ in the engine. In addition, the emissions of most air pollutants (except for $PM_{10}$) and GHGs were estimated to be high in Taxi-Out and Climb-Out modes.

• Journal of the Korean Applied Science and Technology
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• v.33 no.3
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• pp.529-539
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• 2016

Modeling can be used to understand the atmospheric dispersion of air pollutants scientifically. Recent development of model computation enabled to simulate more diverse area. As flowing out from the emission source, the concentration profiles of air pollutants could be estimated in three dimensional space. This study used CALPUFF diffusion model to predict the diffusion of discharged NO2 and TSP on the atmosphere near a combined heat power plant and incinerator. It was investigated contribution concentration of the surrounding area by sources by comparing the actual measurement results and the results of the modeling. Contribution of emission sources to the local level of NO2 was found quite high particularly at the site, A-3. The estimated results by modelling revealed more significant effect on TSP at A-5.

• Journal of Environmental Science International
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• v.17 no.7
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• pp.743-753
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• 2008

Gwangyang Bay is often severely confronted by photochemical pollutants due to its location and dense emissions. It is located in a basin on the south coast of the Korean peninsula and is crossed by a remarkable cluster of hills and mountains of a small horizontal scale that forms a channel. Clearly, the air flow field has a great influence on the dispersion of air pollutants. The characteristics of the wind flow patterns have an important effect on the dispersion of pollutants emitted. In these situations, the distribution of the ozone concentration is extremely complicated because of the superposition of circulations of the air flow fields, especially in complex coastal region. In this study, we examined the distribution of the high level ozone on Gwangyang Bay particularly during the episode day (for 5 years). Among these days, A high level ozone was induced by the development of a sea/land breeze local circulation system, as well as by an anabatic/catabatic flow from the mountains and valley with weakening of the synoptic wind. High level ozone distribution pattern(6 types) on Gwangyang bay is analyzed and the comparison of each pattern reveals substantial localized differences in intensity and distribution of ozone concentration from the site coherence and UPA analysis of ozone concentration. The observed VOC concentration had much difference in concentrations and daily variations between Jungdong and Samil.

• Journal of Integrative Natural Science
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• v.11 no.1
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• pp.30-38
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• 2018

CALPUFF is one of the recommended air pollution models by EPA with AERMOD. It has been used to simulate the ambient concentration of critical air pollutants as well as non-critical pollutants such as persistent organic matters and the organic materials causing odor. In this model, the air pollutants go through dispersion, transportation, chemical reaction, and deposition process. These mechanisms are significantly influenced by meteorological condition. This study produces the meteorological field in three different methods for the simulation of $SO_2$ using CALPUFF: 1) CALMET model by using both ground-level and aerological observation, 2) CALMET model by using MM5 results with NCEP/NCAR reanalyzed data, 3) CALMET model by using MM5 results in which FDDA is applied with NCEP/NCAR reanalyzed data as well as the meteorological data of Korea Meteorological Administration. As a result of CALPUFF model, the resolved concentration of $SO_2$ showed different behaviors in three cases. For the first case, the fluctuation of SO2 concentration was frequently observed while the fluctuation is reduced in the second and third cases. In addition, the maximum concentration of $SO_2$ in the first case was about 2~3 times higher than the second case, and about 4~6 times higher than the third case. These results can be caused by the accuracy of the resolved meteorological field. It is inferred that the meteorological field of the first case could be less accurate than other two cases. These results show that the use of correct meteorological data can improve the result of dispersion model. Moreover, the contribution of various sources such as point, line, and area sources on the ambient concentration of air pollutant can be roughly estimated from the sensitivity analysis.

• Water for future
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• v.28 no.5
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• pp.151-162
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• 1995

A two-dimensional stream tube dispersion model is developed to simulate accurately transverse dispersion processes of pollutants in natural channels. Two distinct features of the stream tube dispersion model derived herein are that it employs the transverse cumulative discharge as an independent variable replacing the transverse distance and that it is developed in a natural coordinate system which follows the general direction of the channel flow. In the model studied, Eulerian-Lagrangian method is used to solve the stream tube dispersion equation. The stream tube dispersion equation is decoupled into two components by the operator-splitting approach; one is governing advection and the other is governing dispersion. The advection equation has been solved using the method of characteristics and the results are interpolated onto Eulerian grid on which the dispersion equation is solved by centered difference method. In solving the advection equation, cubic spline interpolating polynomials is used. In the present study, the results of the application of this model to a natural channel are compared with a steady-state flow measurements. Simulation results are in good accordance with measured data.

• Journal of Korea Water Resources Association
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• v.34 no.4
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• pp.289-301
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• 2001

A fractional step finite difference model for the longitudinal dispersion of nonconservative pollutants is applied to the Nakdong River to simulate the phenol spill accident which occurred on March, 1971. Prior to the dispersion calculation, the flow conditions are simulated to provide inputs to the dispersion model. An unsteady flow model based on Preissmann's four-point scheme is used for this purpose. Sensitivities of the dispersion calculation to empirical equations for dispersion coefficient and to the first-order decay coefficient are analyzed. The time to peak concentration at a downstream location is significantly different depending on the formula for the dispersion coefficient. Although the decay coefficient does not affect the shape of the temporal concentration distribution, the concentration values depend on the decay coefficient verb significantly. An optimization technique is used to calibrate the dispersion model as well as the flow model. The time to the peak concentration is simulated for major positions of water intake along the Nakdong River.

• Analytical Science and Technology
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• v.18 no.5
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• pp.436-443
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• 2005

A study of physical properties and their application using K-powdered activated carbon system followed powdered carbon dispersion was carried out at laboratory. scale. Two types of K-powdered activated carbon for the dispersion have been used in this study to investigate the catalytic removal efficiency of pollutants from the wastewater. From the surface properties obtained for carbon samples treated with aqueous solutions containing potassium salts, main investigations were subjected to isotherm shape, SEM, EDX and surface functional groups. K-powdered activated carbons were dispersed to wastewater with pH variation to investigate the removal efficiency for the color, COD, T-N and T-P. From these removal results of the piggery waste using K-powdered activated carbon, satisfactory removal performance in the region of pH 6~8 was achieved. The excellent effects for the dispersion of the K-powdered activated carbon were proved by the above mentioned properties of the material for adsorption and trapping of organics, and catalytic effects.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.867-874
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• 1994

The complex nature of low flow transport and transformation of nonconservative pollutants in natural streams has been investigated using a numerical solution of a proposed mathematical model that is based on a pair of mass balance equations describing the advection, dispersion, decay and mass exchange mechanisms in streams and in storage zones. In the present study, a mathematical model (named "Storage-Transformation Model") has been developed to predict adequately the non-Fickian nature of mixing and transformation mechanisms for decaying substances in natural streams under low flow conditions. Comparisons of the computed concentration-time curves with the measured data show that the Storage-Transformation Model yields better agreements in general shape, peak concentration and time to peak than the conventional 1-D dispersion model. The proposed model shows significant improvement over the 1-D dispersion model in predicting natural transport and transformation processes in streams through pools and riffles.

• Atmosphere
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• v.24 no.3
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• pp.331-341
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• 2014

In this study, the effects of building-roof cooling on scalar dispersion in three-dimensional street canyons are investigated using a computational fluid dynamics (CFD) model. For this, surface temperature of building roof is systematically changed and non-reactive pollutants are released from street bottom in urban street canyons with the aspect ratio of 1. The characteristics of flow, air temperature, and non-reactive pollutant dispersion in the control experiment are analyzed first. Then, the effects of building-roof cooling are investigated by comparing the results with those in the control experiment. In the control experiment, a portal vortex which is a secondary flow induced by ambient air flow is formed in each street canyon. Averaged air temperature is higher inside the street canyon than in both sides of the street canyon, because warmer air is coming into the street canyon from the roof level. However, air temperature near the street bottom is lower inside the street canyon due to the inflow of cooler air from both sides of the street canyon. As building-roof temperature decreases, wind speed at the roof level increases and portal vortex becomes intensified (that is, downdraft, reverse flow, and updraft becomes stronger). Building-roof cooling contributes to the reduction of average concentration of the non-reactive pollutants and average air temperature in the street canyon. The results imply that building-roof cooling has positive effects on improvement of thermal environment and air quality in urban areas.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.11
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• pp.1168-1179
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• 2006

The validity of an unsteady two-dimensional(2-D) numerical hydrodynamic and pollutant dispersion model(2DNHPDM) was evaluated using the data obtained from I-sa streams in Sooncheon, Chonnam, during rain-fall run-off. Field observations was conducted for 35 hours during the 10 hours rainfall event on 7th May 2005. The water level, 2-D velocity, flow field, and COD at seven points selected along the river were measured at intervals of one hour. The model was applied to describe two-dimensional movement of dissolved pollutants in meandering non-uniform river. Major physical processes affecting the lateral and horizontal mixing of the river flow were simulated. The model was proved effective in describing the hydrodynamics and dispersion of the river pollutants from its major tributaries as well as non-point sources.