In order to determine the future direction of Busan City’s tree planting policy in accordance with changes in automobile fuel and air pollutants, this study selected representative tree species planted in Busan and identified the biogenic volatile organic compounds (BVOCs) emission rate and characteristics of each species. First, representative tree species were selected for each street tree species, forest tree species, and park tree species, and the emission rate and major components of BVOCs were investigated for each tree species. Furthermore, by comparing the ozone generation potential (POCP) for each tree species, tree species with a low emission rate were selected. According to the POCP comparison, P. yedoensis, G. biloba, Z. serrata and C. retusus were selected as roadside tree species, P. densiflora and C. obtusa as forest species, and A. palmatum, C. japonica, and Q. myrsinaefolia were deemed suitable for park species. However, in the case of P. occidentalis, Quercus, and M. glyptostroboides, the emission rates of BVOCs were found to be high. Despite this, these tree species were found to display excellent CO2 absorption and carbon storage. The concentration of NOx in the city center is likely to decrease due to the current trend of transitioning to eco-friendly cars worldwide, resulting in less cars that rely on fossil fuels. Therefore, in the current climate where NOx emissions are still high, planting tree species with a low BVOCs emission rate would be an optimal approach. On the other hand, if the NOx concentration in the city is found to be very low due to changes in automobile fuel use, planting tree species with excellent BVOCs emission capacity and CO2 absorption would be ideal.

This study was carried out to develop a system to reduce ultrafine dust using hygroscopic materials such as glycerin and propylene glycol. Prior to the development of an ultrafine dust reduction system, the moisture condensation efficiency of glycerin and propylene glycol was investigated based on relative humidity (RH). The results showed that when no substances (glycerin and propylene glycol) were added to a tedlar bag, the relative humidity and temperature remained constant. The moisture condensation efficiency of glycerin was 60%, and the time it took to reach 50% of the initial relative humidity was about 40minutes. In the case of propylene glycol, the moisture condensation efficiency was 75%, and the time it took to reach 50% of the initial relative humidity was about 10 minutes. When glycerin and propylene glycol mixture was added, the moisture condensation efficiency was 68% and it took 20 minutes to reach 50% of the initial relative humidity. These results suggest that hygroscopic materials such as glycerin and propylene glycol can actually condense moisture in the atmosphere. In addition, considering actual atmospheric conditions, the relative humidity was set to 60% and 40% or less, and the moisture condensation efficiency was measured. The results showed that the mixture of glycerin and propylene glycol yielded the highest condensation efficiencies, at 69% and 62%, respectively. Therefore, it is preferable to use a mixture of glycerin and propylene glycol to condense moisture in the range of relative humidity in the actual atmosphere.

In this study, the distribution characteristics of particulate matter (PM) in subway platforms were investigated, and the performance of hybrid filter systems was determined through the removal efficiency of PM according to various flow rates and filter structures. The hybrid filter systems were constructed in magnetic systems as (Magnet-Magnet (MM) filters and Magnet-Cascade (MC) filters). PM removal efficiencies of these filters were investigated at a subway platform for three days including weekdays and weekends. The compositions of collected PM were also analyzed. Based on the PM measurement in the subway platforms, it was confirmed that the operation of trains had a significant effect on the increase of PM concentration, and a large number of PMs were less than 1 μm in size. For the MC filter, the removal efficiency of PM1 based on the number of particles was up to 30.5%, demonstrating a relatively high removal efficiency in comparison with the MM filter. In terms of PM10, PM removal efficiencies of the MC filter with respect to the mass concentration and the number of particles were 48.3% and 14.5%, respectively. For the MC filter, it was found that the PM removal efficiency was enhanced with the increase in the flow rate. Moreover, the relatively large particle size PM (i.e., 7.5 μm - 10 μm) denoted a maximum removal efficiency of 97% in terms of the number of particles. All PMs collected by the filter were Fecontaining PMs. As a field experiment using the hybrid filter, the applicability of magnetic particle control technology was approved. Based on this result, it is expected that this study will be used as background research for the development of fine dust control technologies in a subway environment.

Experiments were conducted to analyze the concentration of sulfur compounds present in ambient air at the pg or ppt level. The compounds were estimated using GC/PFPD (Gas Chromatography with Pulsed Flame Photometric Detector) analyses with a Thermal Desorber (TD). The analytical results showed very stable and precise retention time values (RSD: ＜ 0.22%), peak area (RSD: ＜ 3.9); the coefficients of the calibration curves were also determined (r²: ＞ 0.991). Also, with respect to the recovery rates of the sulfur compounds from dry air, those for H₂S, MM, DMS and DMDS were 94, 100, 113 and 114%, respectively. In order to evaluate the sulfur chemicals in humid air, a study was conducted at RH of 55 and 100%. The recovery rate at a relative humidity of 55% was similar to that under dry conditions. However, recovery rates of H₂S and MM at RH 100% were reduced to 70 and 77%, respectively.

The standard emission rate(ERs) of isoprene was quantitatively measured in situ from Quercus mongolica Fischer that dominates more than about 85% of domestic oak trees. The ERs values in spring and summer were similar to 64.4 and 58.1 (㎍C/gdw/hr), respectively. The ERs in autumn, 7.06(㎍C/gdw/hr), was about 8～9 times lower than those in spring and summer. The coefficient of determination (r2) between ERs and CL․CT ranged from 0.593 to 0.836. The correlation coefficients between the ERs and PAR, the ER and temperature suggested that ERs have strong correlation with PAR(photosynthetically active radiation) and temperature. In addition, the high values of PAR, temperature, and ERs were found in the time zone of 15:00 ～17:00(spring), 15:00 ～ 16:00(summer), and 14:00 ～ 15:00(autumn).