• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.136-138
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• 2000

The vehicle emissions of primary air pollutants are described by the emission factor (EF), defined as the emitted mass (g) of a compound per distance (km) and vehicle. The EF can be determined by exhaust measurements from single vehicles in dynamometric tests. However, the EF of a large number of vehicles has to be measured to obtain the representative results for actual road traffic emissions. Road traffic emissions can also be determined by exhaust measurements of driving vehicles or in tunnel measurements. (omitted)

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.1
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• pp.69-77
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• 1993

Exhaust emissions are calculated as a product of the emission factor and the vehicle kilometer traveled(VKT). The emission factor is a function of several parameters such as vehicle model year, vehicle mileage, traffic conditions, etc. The representative driving cycles classified as ten different types of an average vehicle speed were selected by analyzing passenger car driving patterns in Seoul. 51 vehicles were sampled and analyzed by types of vehicles, fuels used, model years and vehicle mileages also, exhaust emissions of them were measured by chassis dynamometer. Regression equations between average vehicle speeds and exhaust emissions are made for the estimation of emission factors at different vehicle speeds. Annual emission rates of air pollutants from motor vehicles in Korea were 1116$\times10^3 ton, 149\times10^3 ton, 413\times10^3 ton and 67\times10^3$ ton for CO, HC, NOx and particulats, respetively in 1990. It was found that 56% of CO and 49% of HC were originated from passenger cars and taxis, in addition, 87% of NOx and 100% of particulates were from buses and trucks using diesel fuels.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.6
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• pp.589-598
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• 1998

This study was conducted to investigate the chemical characteristics of Precipitation at Seoul, Yangpyong, Hongchon and Inje in the central part of Korean peninsula during the period from March 1994 to November 1997. The precipitation samples were collected by automatic wet-only sampler. The samples were analyzed for major anions (SO42-, NO3-, Cl-, F-) and cations(NH4+, Ca2+, Mg+, Na+, K+), in addition to acidity and electrical conductivity. The analytical instrument for water soluble ionic components was ion chromatography. The volume - weighted mean PH were 4.73, 4.87, 4.89 and 4.81 at Seoul, Yangpyong, Hongchon and Inje, respectively. The sums of cation concentrations was slightly greater than the sums of anion concentrations. Also, the highest ion component was SO42- in anions and NH4+ in cations. The mean equivalent ratios of SO42- to NO3- were found by 2.96, 2.71, 2.43 and 2.25 at Seoul, Yangpyong, Hongchon and Inje, respectively. The factor analysis was conducted in order to make the large and diverse data set as manageable levels and to qualitatively examine the relationship between the variables. It showed that major sources of pollutants in precipitation were from the anthropogenic in Seoul, the natural in Hongchon, and the anthropogenic and natural in Yangpyong and Inje.

• Journal of Korean Society for Atmospheric Environment
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• v.8 no.4
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• pp.213-220
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• 1992

Simple correlation analysis, factor analysis, and multi-variate analysis have been performed to analyze the relationship between air pollution and meteorological factors for air pollution and meteorological data measured at Kwanghwamun in Seoul during the period of one year(January 1990 $\sim$ December 1990). As a result of simple correlation and factor analysis, $SO_2$, TSP and CO concentrations have shown high negative correlation with temperature and among these indicating that these are related with pollutant emission trend based upon heating fuel usage. Ozone has a good corrleation with solar radiation and relative humidity to have a closed relation with $O_3$ generation reaction mechanism. The result of multi-variate correlation analysis shows that the concentration of $SO_2$ and CO are adequate for correlation model with ambient temperature and wind speed and $O_3$ concentrations are adequate for that with solar radiation and wind speed. $SO_2$ and CO levels are considered to be affected first of all by heating fuel usage as a emssion source and wind speed as a dispersion effect. The $SO_2$ concentration in the condition that the temperature fall below zero is explained by multilicative model with wind speed, only one variable.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.5
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• pp.383-396
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• 1997

Numerical prediction of the pollutant dispersion over a two-dimensional hilly terrain is presented. The dispersion model used in the present work is based on the gradient diffusion theory and the finite-volume method on a non-orthogonal boundary-fitted grid system. The numerical model is validated by comparing the results with the available experimental data for the flat-floor dispersion within a turbulent boundary-layer. The numerical error analysis is performed based on the guideline of Kasibhatla et al.(1988) for the elevated-source dispersion in the flat-floor boundary layer having a power-law velocity and linear eddy-diffusivity profile. The influences of the two-dimensional hilly terrain on the dispersion from a continuously released source are numerically investigated by changing the emission locations and heights. It is found that the distributions of ground-level concentration are strongly influenced by the source location and the emission height. Hence, the terrain amplification factor is greatly enhanced when the pollutant source is located within a flow separation region. Dispersion from a source of short duration is also simulated and the duration time of the pollutant is compared at several downstream locations on a hilly terrain. The results of the numerical prediction are applied to the evaluation of environmental impacts due to the automobile exhausts at the seashore highway with a parallel mountain range.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.E1
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• pp.9-18
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• 2006

Aerosol hygroscopic properties were measured by a tandem differential mobility analyzer (TDMA) system during the Aerosol Characterization Experiment (ACE)-Asia campaign from 31 March to 1 May 2001. Two high flow differential mobility analyzers (DMAs) were used to maximize the count rate on board the Center for Interdisciplinary Remotely Piloted Aircraft (CIRPAS) Twin Otter aircraft. Hygroscopic growth factor distributions of particles having initial dry nanoparticle diameters of 0.040, 0.059, 0.086, 0.126, 0.186, 0.273, 0.400, and $0.586{\mu}m$ were measured during 19 research flights. Data collected during 12 of those flights were used to investigate aerosol mixing state and the influence of aerosol source region on size-resolved hygroscopicity. The uniformity in size-resolved hygroscopicity was quantified to facilitate comparison between measurements made in different air masses. Hygroscopic growth factors are strongly dependent on source region and sizes. Mean hygroscopic growth factors were observed to be greatest when the air mass origin was from the south. The mean growth factors for continental sources decreased with initial size from 1.47 to 1.27 for $0.040{\mu}m\;and\;0.586{\mu}m$, but increased with initial size from 1.44 to 1.8 for $0.040{\mu}m\;and\;0.400{\mu}m$ dry diameters for marine sources.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.3
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• pp.383-391
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• 2006

In Korea, the major source of serious air pollution is motor vehicles. Air pollution from vehicles has been annually increased. Then the government will try to control the vehicle emission by applying the effective emission management policy for the manufactured and in-used car. It is necessary to correctly calculate the emission factor for successful propulsion of the vehicle emission control policy. In this study, correlation analysis of exhaust emissions from vehicles between CVS-75 mode and Korea mode was conducted. A total of 25 light-duty buses were tested on the chassis dynamometer system in order to measure CO, HC, NOx PM and fuel efficiency (F.E.). For the test modes, 10 different Korea modes and CVS-75 mode were used. As the result of correlation analysis between those modes, most of the correlation coefficients were higher than 0.90. On the basis of high correlation between those modes, correction factors by driving conditions were estimated. Through the results of this study, we obtained essential basic data to correct difference from those modes.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.E1
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• pp.1-9
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• 2003

The soil concentrations of polychlorinated biphenyls (PCBs) were measured at 12 sites in Ansung, Kyonggi province, Korea. Correlation coefficient (r) between total PCBs and organic matter content (OM) was significant (r=0.562, p< 0.05). It suggests that organic matter may be a key factor of soil absorption of PCBs. The PCB concentrations of low chlorinated congeners with high vapor pressure were relatively abundant in air but high chlorinated congeners with low vapor pressure were mainly dominated by soil. The results indicated the influence of physicochemical properties of PCBs such as vapor pressure, octanol - air partition coefficient ( $K_{OA}$ ). The calculated soil/air fugacity quotients suggested that the soil may be a source of heavier molecular PCBs (>penta-CBs) to the atmosphere, where lighter molecular PCBs appear to be affected by a movement from air to soil, especially tetra-CBs. Therefore, PCB homologs with low vapor pressure might have been influenced by revolatilization from soil.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.4
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• pp.377-386
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• 2003

In order to develop a confident sampling technique, we designed and constructed a 6-port manifold MFC sampling system for collecting gaseous pollutants in air. Using this instrumentation, we tested the performance criteria of MFC system in terms of: (1) flow rate; (2) MFC-to-MFC variability; (3) tube-to-tube variability; and (4) time. It was interesting to find that the later two factors did not show any significant variations, while the former two show substantially large variations. However, as most of those variabilities are consistent enough to form systematic patterns, we were able to explain the occurrence patterns of all those MFC biases in terms of those four major variables. The overall results of our experiment suggest that one needs to use correction factor for each MFC unit under a given flow rate to maintain optimal accuracy and precision for sampling of those pollutants.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.1
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• pp.51-56
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• 2001

This study was carried out to interpret mathematically hydraulic behaviour in packing tower which packed 50 mm plastic Hiflow-ring with a dimension of 300 mm wide and 1,400 mm high. In view of energy saving, the recent packing. 50 mm plastic Higlow-ring was superior to conventional packings because of low pressure drop in high loads. As relative error between numerically predicted and experimentally obtained values was less then 6% in the loading and flooding point, it found that therir results appeared to be adequate. Comparison of hose two values in both dry and wet packing conditions. relative errors amount to 3.96 and 5.6%, respectively. In order to evaluate the operating characteristics of packing, the type, size, and material for packings must be estimated in various system and loads. This study is able to calculated pressure drop, hold-up, gas and liquid loads using mathematical interpretation. For these calculation, the specific constants of each packings must be calculated first all. The method of mathematical interpretation in this study turned out to be superior to the existing methods because of reduced errors at loading and flooding point.