• Journal of Environmental Science International
• /
• v.17 no.5
• /
• pp.501-507
• /
• 2008

The concentrations of HCHO(formaldehyde), $PM_{10}$(particulate matter), $CO_2$(carbon dioxide) and TBC(total bacteria counter) distribution in schools(Chung-Nam Area) were examined, and the results were compared with the recommended criterion of the administration law of indoor air. The subjects were an elementary school, a middle school and a high school in Chung-Nam area, and the concentration of TBC was examined by Single Stage Air Cascade Sampler, which applied the inertia collision catching method of 28.29L/min(flux) during 5 months from March, 2007 to July, 2007. The instrument(LD-3B, SIBATA Company)was used to examine $PM_{10}$, by a light scattering method and a light transmission method. The instrument(Airboxx(KD Engineering) was used to examine $CO_2$. The instrument(Z300XP(Environmental sensor)was used to examine HCHO. The result indicated that the $PM_{10}$ average concentrations of the surveyed classrooms were $49{\mu}g/m^3$ in Spring and $59{\mu}g/m^3$ in Summer. The $CO_2$ average concentration of the surveyed schools were 576 ppm in the classroom and 527 ppm in the stateroom. The average concentration of TBC were $729CFU/m^3$ in an elementary school, $401CFU/m^3$ in a middle school, $381CFU/m^3$ in a high school. The HCHO average concentration of the surveyed schools were 0.03 ppm in the classroom, 0.02 ppm in the stateroom.

• Transactions on Electrical and Electronic Materials
• /
• v.13 no.6
• /
• pp.305-309
• /
• 2012

In this study, ZnO nanorods and $SnO_2$-CuO heterogeneous oxide were grown on membrane-type gas sensor platforms and the sensing characteristics for carbon monoxide (CO) were studied. Diaphragm-type gas sensor platforms with built-in Pt micro-heaters were made using a conventional bulk micromachining method. ZnO nanorods were grown from ZnO seed layers using the hydrothermal method, and the average diameter and length of the nanorods were adjusted by changing the concentration of the precursor. Thereafter, $SnO_2$-CuO heterogeneous oxide thin films were grown from evaporated Sn and Cu thin films. The average diameters of the ZnO nanorods obtained by changing the concentration of the precursor were between 30 and 200 nm and the ZnO nanorods showed a sensitivity value of 21% at a working temperature of $350^{\circ}C$ and a carbon monoxide concentration of 100 ppm. The $SnO_2$-CuO heterogeneous oxide thin films showed a sensitivity value of 18% at a working temperature of $200^{\circ}C$ and a carbon monoxide concentration of 100 ppm.

• Journal of the Korean Society of Tobacco Science
• /
• v.24 no.1
• /
• pp.38-45
• /
• 2002

This study was conducted to determine the smoke component concentration and the smoke distribution in the cambridge filter pad and cigarette filter with stalk position and grade of Korean leaf tobaccos. 12 grades of flue-cured and burley leaf tobaccos which were taken from the Kim-cheon and Ock-cheon leaf tobacco processing factory were used for this study. Six kinds of smoke components such as tar, nicotine, water, carbon monoxide(CO), carbon dioxide($CO_2$) puff No. collected in the cambridge filter pad and cigarette filter were analyzed. Also, nicotine/tar, CO/tar ratio were calculated from the analytical data. Puff no., CO, and $CO_2$ concentration of flue-cured and burley tobacco leaves at high stalk position were higher than those of low stalk position, and these components were increased in high grade of leaf tobacco. Compared with flue-cured tobacco, burley tobacco showed a little values of puff no., nicotine, and tar concentration. The pH range of burley tobaccos was broader than that of flue-cured tobaccos, and the ammonia concentration of burley tobaccos was significantly higher than that of flue-cured tobaccos. The pH value and ammonia concentration of burley tobaccos were decreased as stalk position of leaf tobaccos decreased. The distribution of smoke components collected in the cambridge filter pad and cigarette filter was different with a different grade and stalk position of tobacco leaves. In high stalk position of tobacco leaves, the portion of smoke components collected in the cambridge filter pad was also increased. The average nicotine, water, and tar removal efficiency by a cigarette filter in a flue-cured tobacco were 37%, 64%, and 48%, respectively. Compared with flue-cured tobaccos, smoke components of burley tobaccos had high nicotine and low water removal efficiency by a cigarette filter. The average ratio of nicotine/tar and CO/tar of flue-cured tobaccos and burley tobaccos were 0.097, 1.22, 0.094, and 0.97, in order. Nicotine/tar ratio was decreased and CO/tar ratio was increased in low stalk position.

• Journal of Korean Society for Atmospheric Environment
• /
• v.6 no.1
• /
• pp.1-10
• /
• 1990

The purpose of the study was to analyze air quality in underground shopping centers using pattern recognition methods. In order to perform this, the concentraion of air pollutants such as $CO, NO_2, NO_x, SO_2$, and particulate matters was measured at the 11 different shopping centers in Seoul metropolitan area and the total of 47 samples were obtained at random based on the size of shopping centers. To introduce a new concept of the "average concentration" for the indoor air quality analyses, the various multivariate statistical analyses have been studied. Thus, a cluster analysis was applied to separate the samples into pseudo-patterns and a disjoint principal component analysis was used to generate homogeneous patterns after removing outliers from the pseudo-patterns. The 6 homogeneous patterns were then obtained as follows:the first pattern was a group of clean sites;the second a group of sites having high dust concentration;the third a group of sites having high dust and $NO_x$ concentration;the fourth a group of sites having low dust and $SO_2$ concentraion and high CO concentration;the fifth a group of sites having high $NO_2 and SO_2$ concentration;and the final a group of miscellaneous sites. Thus, the average concentration could be estimated for each pattern.h pattern.

• Particle and aerosol research
• /
• v.17 no.4
• /
• pp.107-114
• /
• 2021

In this study, the effect of the air purifier located in the living room on the reduction of PM_2.5 concentration in the living room and bedroom was investigated. Measurements were carried out in real-life for about 2 weeks in a Korean apartment building where a 3-person household had lived and the exclusive private area was 84.9 m². When the air purifier in the living room was operating, the change in PM_2.5 concentration was measured when the door to the bedroom connected to the living room was opened and closed. In the case of living with the bedroom door open, the average PM_2.5 concentrations in the living room and bedroom were almost the same. When living with the bedroom door closed, the average PM_2.5 in the living room was higher than in the bedroom. The ventilation and cooking effects in the living room mainly affected the PM_2.5 concentration in the living room. Only one air purifier in the living room was able to keep the PM_2.5 concentration in the living room and bedroom low.

• Journal of Hydrogen and New Energy
• /
• v.18 no.4
• /
• pp.382-390
• /
• 2007

To check the feasibility of SMART(Steam Methane Advanced Reforming Technology) system, an experimental investigation was performed. A fluidized bed reactor of diameter 0.052m was operated cyclically up to 10th cycle, alternating between reforming and regeneration conditions. FCR-4 catalyst was used as the reforming catalyst and calcined limestone(domestic, from Danyang) was used as the $CO_2$ absorbent. Hydrogen concentration of 98.2% on a dry basis was reached at $650^{\circ}C$ for the first cycle. This value is much higher than $H_2$ concentration of 73.6% in the reformer of conventional SMR (steam methane reforming) condition. The hydrogen concentration decreased because the $CO_2$ capture capacity decreased as the number of cycles increased. However, the average hydrogen concentration at 10th cycle was 82.5% and this value is also higher than that of SMR. Based on these results, we could conclude that the SMART system can replace SMR system to generate pure hydrogen without HTS (high tempeature shift), LTS (low temperature shift) and $CO_2$ separation process.

• Journal of Korean Society for Atmospheric Environment
• /
• v.30 no.2
• /
• pp.128-138
• /
• 2014

This study has analyzed the concentration variation of four air pollutants ($PM_{10}$, $NO_2$, CO, and $SO_2$) during the typhoon periods over 10 years (2002~2011). In this study, 10 typhoon events which had rainfalls in Korean Peninsula were selected during the study period. The analysis was performed using the observation data of both the air pollutants and rainfall. In order to examine and compare the concentrations of the air pollutants between normal periods and typhoon periods, we have obtained monthly average concentrations from July to September and daily average concentrations during typhoon periods. For the period from July to September, 34% of the total rainfalls can be explained by typhoons, and the concentration of air pollutants during the typhoon period was lower than the normal period. In addition, the concentration variations of the pollutants during the typhoon period were analyzed according to two categories: differences in the concentrations between the day before and the day of the typhoon (Case 1) and between the day before and after the typhoon (Case 2). The results indicated that the reduction rate of $PM_{10}$, $NO_2$, CO, and $SO_2$ was 30.1%, 17.9%, 11.6%, 9.7% (Case 1) and 22.8%, 21.0%, 9.0%, 8.0% (Case 2), respectively. This result suggested that air quality was significantly improved during the typhoon period than after the typhoon period by the rainfall.

• Journal of Korean Society for Atmospheric Environment
• /
• v.10 no.4
• /
• pp.217-223
• /
• 1994

Carbon dioxide emission has been increased by 7% in an annual average toward 212.5 million tons in 1990 from 108.7 million tons in 1980. Among emissions in 1990, industry, residential / commercial, transportation, other and non-energy have occupied 91.12, 68.04, 42.13, 7.13 and 4.09 million tons respectively. The Korea-scenarios corresponding to those of IPCC that is Intergovernmental Panel on Climate Change (A : modest control of $CO_2$; B : stringent control of $CO_2$, C: shifting fuel to renewable and nuclear energy in the second half of the next century ; and D: shifting fuel to renewable and nuclear energy in the first half of the next century show that the global-scale contributions of atmospheric $CO_2$ concentration are 0.77, 0.64 and 0.78% in 2050 for cases A,B, and C respectively. In all cases, the contributions were smaller than 0.09 % in 1985.

• Journal of Environmental Science International
• /
• v.16 no.2
• /
• pp.187-195
• /
• 2007

Long-term passive diffusive samplers(PDS) have been used to measure $NO_2\;and\;SO_2$ concentrations at 21 sampling sites in Daejeon, Korea during the period of January 2000 - December 2002. The spatial distributions of annual $NO_2\;and\;SO_2$ concentrations were mapped. Average annual $NO_2$ concentration over the sampling period was $28.5{\pm}12.5\;ppb$, ranging from 1.2 to 81.7 ppb. Average annual $SO_2$ concentration over the sampling period was $7.7{\pm}4.8\;ppb$, ranging from 0.6 to 26.8 ppb. On average, $NO_2$ concentration was approximately 5.8%(1.6 ppb) larger in 2002. $SO_2$ concentration was decreased by 13%(1.1 ppb) during the sampling period. The seasonal variation of $NO_2\;and\;SO_2$ concentration was observed with a tendency to be higher in fall and winter. $NO_2\;and\;SO_2$, concentrations measured at different site types(patterns of land use) show significant difference. The observed difference in concentration was associated with difference in emissions of $NO_2$ from motor vehicles and $SO_2$ by non-traffic fuel consumption for heating.

• Korean Journal of Human Ecology
• /
• v.19 no.4
• /
• pp.745-760
• /
• 2010

The purposes of this study were to investigate the state of indoor thermal and air environment during winter in the one-room type multi-family houses occupied by university students and to analyze factors which influenced this environment. Field survey was conducted in 10 houses between 30th January, 2009 and 13th February, 2009 which measured indoor thermal and air elements as well kept records of interviews with residents and other related factors. Measured elements were air temperature, relative humidity, as well as concentrations of $CO_2$, CO, TVOC, and PM-10. The results can be summarized as follows. 1) The mean air temperature in each house ranged from 19.3 to $25.3^{\circ}C$, so most houses were not suitable for evaluation criteria($20-22^{\circ}C$). The average $CO_2$ concentration in each house was 965~3259ppm, so most houses exceeded evaluation criteria(1000ppm). The average TVOC concentration in each house were 0.00~1.17ppm, 5 houses exceeded evaluation criteria(0.12ppm). 2) Relative humidity, CO concentration, and PM-10 concentration were suitable for evaluation criteria. Therefore, indoor thermal and air environment during winter in one-room type multi-family housing occupied by university students was found to be generally uncomfortable. Important factor which were found to influence air temperature and the concentration of $CO_2$ were smaller space capacity than general house. Other factors which were found to influence the environment of these houses were the existence of a balcony as well as factors relating to the behavior of occupants such whether or not heating were operated, whether windows were opened, whether fans used, whether occupants smoked or used cosmetics, and whether the space was dusted.