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).

In order to investigate the compositions and the emission rates of monoterpenes emitted from coniferous trees, those from Larix leptoleis (Sieb. et Zucc.) Gordon were measured. In spring and summer, the major monoterpenes were α-terpinene, α-pinene, myrcene; however, α-pinene and α-terpinene were most abundant in fall. The total mean monoterpene emission rates were 0.455 (㎍C/gdw/hr) during the whole period. The higher monoterpene emission rates were found in fall compared to those in spring and summer. In addition, the slopes (β value) between emission rate and temperature were two times lower in fall than those in spring and summer. It was also found that Larix leptoleis (Sieb. et Zucc.) Gordon had lower monoterpene emission rates than P. densiflora and P. rigida.

In this study, the distribution characteristics of volatile organic compounds (VOCs) were investigated on the seasonal basis across spring, summer, and fall during the year of 1998. According to this analysis, most VOC species investigated exhibited strong temporal trends. Over diurnal scale, there distribution characteristics were affected by seasonal factors strongly. While they showed high day/night ratio pattern during spring, the pattern was reversed during fall. When the seasonal mean values were compared between the two seasons, the spring values were systematically higher than their counterparts in most cases. In addition when our VOC measurement data were compared with those reported from elsewhere, we were able to conclude that the VOC levels in the study area are comparable to the level weakly impacted by the regional emissions of VOCs. Although our data are not sufficient enough to systematically explain the atmospheric distribution and behavior of VOCs, the findings of strong correlations among some of VOC species suggests strong need for investigating their interactions in the earth's atmosphere.