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The objective of this study was to explore the characteristics of concentration of indoor air pollutants, such as PM 10 , CO 2 , and NO 2 , measured by tele-monitoring system in a Seoul Metropolitan underground railway station from January 1, 2008 to December 31, 2012. The annual average concentration of indoor air pollutants actually varied over a wide range and was found to exhibit marked variation with time and measurement sites (tunnel inlet, platform, and concourse). After installing platform screen doors, the average PM 10 concentration on platform and concourse was decreased by 43.8% and 31.2%, respectively during the study periods. The relationship between the concentration of PM 10 and meteorological parameters (relative humidity and rainfall) or the Asian dust events was regarded as statistically significant. The correlations between the number of boarding/alighting passengers and PM 10 , CO 2 , and NO 2 were calculated. A p-value of less than 0.01 was regarded as significant except NO 2 . The I/O ratio of PM 10 concentration was elevated after a congested time (about 08:00 am). The average I/O ratios of NO 2 were observed in concourse and platform on 03:00 am with 1.76±0.91 and 1.50±0.51, respectively. The average daily variation of standard excess rate of PM 10 and NO 2 concentration in concourse and platform was investigated. The highest standard excess rate was observed on 21:00 (09:00 pm). Cheng and Yan, 2011;Lee et al., 2010;Salma et al., 2009;Kim et al., 2008;Park and Ha, 2008

The aim of this study is to analyze error cases induced during the proficiency test of certified odor measurement agencies. In the case of the homogeneity test performed in three panel groups, the geometric mean dilution factor of the site boundary PTMs(proficiency testing materials) was 1.4 ± 0.2, 1.7 ± 0.2, 1.8 ± 0.1 and that of the outlet PTMs was 3.7 ± 0.2, 3.7 ± 0.3, 3.7 ± 0.3, respectively. In the case of the stability test for 72 h, the geometric mean dilution factor of the site boundary PTMs was 1.6 ± 0.1 and that of the outlet PTMs was 3.6 ± 0.1. Among error cases induced during the proficiency test of certified odor measurement agencies, the proportion of error cases was in the order of case II(discontinuance of estimation)(40.0%) > case I(error on estimation procedure by panelist)(33.3%) > case III(miswriting of estimation result)(13.3%) > case IV(miswriting of dilution factor) and V(writing of wrong estimation result)(6.7%). Therefore, it seems likely that additional education related to error cases II and I is required.

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This study aimed to evaluate the characterization of a metal oxide semiconductor and electrochemical gas sensor array for measuring wastewater odor. The sensitivity of all gas sensors observed in sampling method by stripping was 6.7 to 20.6 times higher than that by no stripping, except sensor D (electrochemical gas sensor). The average reduction ratio of sensor signal as a function of initial dilution rate of wastewater was in the order of food plant > food waste reutilization facility > plating plant. The sensitivity of gas sensors was dependent on both the type of wastewater and the dilution rate. The sensor signals observed by the gas sensor array were correlated with the dilution factor (OU) calculated by the air dilution sensory test with several wastewater (r 2 =0.920~0.997), except the sensor signals of sensor D measured in the plating plant wastewater. It seems likely that the gas sensor array plays a role in the evaluation of odor in wastewater and is useful tool for on-site odor monitoring in the wastewater facilities. Received : Nov. 24, 2014, Revised : Dec. 10, 2014, Accepted : Dec. 22, 2014 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License(http://creativecommons.org/ licenses/bync/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.