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Versoza, Michael,Park, Duckshin Korean Association for Particle and Aerosol Resear 2017 Particle and Aerosol Research Vol.13 No.2
Radon ($Rn^{222}$) is a radioactive gas and is found at high concentrations underground. Investigations were done in many years specifically on public transportations such as in the subway stations, concourses and platforms for these are located underground areas. This study correlates the $Rn^{222}$ concentrations with the Particulate Matter (PM) concentration for the gas could be attached or trapped inside these particles. It was done on the opening subway tunnel of Miasageori Station going to Mia Station (Line 4) last August 2016. Based on the result, the $Rn^{222}$ were more influenced on the mass ratio (%) of PM present in the air instead of its mass concentration (${\mu}g/m^3$). As the $PM_{10}$ mass ratio increases ($42.32{\pm}1.03%$) during morning rush-hours, radon starts to increase up to $0.97{\pm}0.03pCi/L$. But during the afternoon $Rn^{222}$ concentrations decreased while the composition were stable at $22.96{\pm}3.0%$, $39.04{\pm}0.6%$ and $38.01{\pm}0.3%$ in $PM_1$, $PM_{2.5}$ and $PM_{10}$ respectively. It was then assumed that it could be the composition of the morning hours of the station were influencing the concentration of the radon.
실시간 측정장비를 활용한 석유화학단지 입자상오염물질 및 휘발성유기화학물의 농도 특징
김종범,박덕신,박세찬,Micheal Versoza,이용일,이상신,박종성,김정호 한국대기환경학회 2019 한국대기환경학회지 Vol.35 No.6
Different air pollutants are being exhausted from the petrochemical industrial complex because of using various chemical substances. Some of these pollutants are volatile organic compounds (VOCs), with the likes of benzene that has carcinogenic properties. In this study, the research focused on monitoring daily variation of air pollutants such as volatile organic compounds (VOCs), particulate matter (PM), and black carbon (BC). Real-time monitoring devices, including Portable Gaschromatography for VOCs, were used and placed nearby petrochemical industrial plants. Results showed that PM10 and PM2.5 concentrations were at low concentrations both measuring point and air quality monitoring station (AQMS). Moreover, BC concentrations were at low levels as well as other forms of VOCs were found to be lower than the national or international standard guideline. However, the concentration of Total VOC and Benzene were 46.1±42.2 ppb and 2.6±3.5 ppb, respectively. The National standard of benzene is 1.5 ppb (5 μg/m3) per year average, and the results of this study sometimes exceed it. This study would suggest that the need for a real-time monitoring system is a must because high concentrations were detected on a daily basis. Furthermore, additional research on carcinogenic substances such as benzene and 1.3-butadiene was detected even in the area with great distances from petrochemical plants.
Generation Characteristics of Nanoparticles Emitted from Subways in Operation
Lee, Yongil,Choi, Kyomin,Jung, Wonseog,Versoza, Michael E.,Barabad, Mona Loraine M.,Kim, Taesung,Park, Duckshin [Chinese Association for Aerosol Research in Taiwa 2018 Aerosol and air quality research Vol.18 No.9
<P> In this study, measurements were carried out to identify the generation characteristics of wear particles emitted under a subway cabin during operation. Along with a fast mobility particle sizer, probes were installed under a subway cabin and in a subway tunnel to measure the size distributions of nanoparticles at 1-s intervals. Based on the particle density measured under the cabin minus that measured in the tunnel, the size distribution of wear particles generated under the cabin during deceleration was estimated to be bimodal at 165.5 nm and 6.98 nm. These particles were most likely generated from wheel-rail contact, as the train utilized electric braking (no mechanical force applied). In addition, a change in the wear mechanism appears to have arisen due to the increased temperature of the wheel-rail contact while nanoparticles were being emitted, leading to an initial generation of 165.5-nm particles followed by 6.98-nm particles 1 s later. </P>