• Journal of environmental and Sanitary engineering
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• v.24 no.1
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• pp.47-55
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• 2009

Indoor air Quality in public facility same as bus terminal and subway station is very important for civil health. The purpose of this study was to investigate the concentration and distribution of PM10 and falling microorganism at the 5 subway stations and bus terminals from Summer 2003 to Summer 2005 in Kyunggi Province. The results were as follows. 1. The highest concentration of PM10 was $187ug/m^3$ at Bucheon Bus Terminal in 2005 while the lowest concentration of PM10 was $78ug/m^3$ at Suwon Bus Terminal in 2003. The year variation of PM10 concentration at the bus terminals in Kyunggi Province was in order of 2005 > 2004 > 2003. The average concentration of PM10 at the five Bus Terminal was $127ug/m^3$. 2. The highest concentration of PM10 was $225ug/m^3$ at Euijungbu Station l in 2004 while the lowest concentration of PM10 was $115ug/m^3$ at Suwon Station in 2003. The year variation of PM10 at the subway stations in Kyunggi Province was in order of 2004 > 2005 > 2003. The average concentration of PM10 at the five subway stations was $164ug/m^3$. 3. The average amount of falling microoganism at the five bus terminal in Kyunggi Provinc was 201CFU/plate. The minimum is 124 CFU/plate at Seongnam Bus Terminal in 2004 while the maximum is 268CFU/plate at Euijungbu Bus Terminal in summer 2005. The higher concentration of PM10 was 206CFU/plate in 2004 than 199CFU/plate in 2003 and 2005. 4. The minimum is 107CFU/plate at Anyang station in 2003 while the maximum was 263CFU/plate at Euijungbu station in 2003. The average amount of falling microoganism at the five subway stations in Kyunggi Province was 179 CFU/plate. The year variation of falling microorganism at the subway stations in Kyunggi Province was in order of 2004 > 2005 > 2003.

• Journal of Powder Materials
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• v.10 no.4
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• pp.262-269
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• 2003

Nano-sized Ni-ferrite powder was fabricated by spray pyrolysis process using the waste solution resulting from shadow mask processing. The average particle size of the powder was below 100 nm. The effects of the concentration of raw material solution, the nozzle tip size and air pressure on the properties of powder were studied. As the concentration increased, the average particle size of the powder gradually increased and its specific surface area decreased, but size distribution was much wider and the fraction of the Ni-ferrite phase greatly increased as the concentration increasing. As the nozzle tip size increased from 1 mm to 2 mm, the average particle size of the powder decreased. In case of 3 mm nozzle tip size, the average particle size of the powder increased slightly. On the other hand, in case of 5 mm nozzle tip size, average particle size of the powder decreased. Size distribution of the powder was unhomogeneous, and the fraction of the Ni-ferrite phase decreased as the nozzle tip size increasing. As air pressure increased up to 1 kg/$cm^2$, the average particle size of the powder decreased slightly, on the other hand, the fraction of the Ni-ferrite phase was almost constant. In case of 3kg/$cm^2$ air pressure, average particle size of the powder and the fraction of the Ni-ferrite phase remarkably decreased, but size distribution was narrow.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.5 no.1
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• pp.16-39
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• 1995

From July 8 to September 2 1994, asbestos exposure level among asbestos textile workers was surveyed. Six plants out of plants in Korea were selected for this study. In addition to the exposure level, the relationship between the level of exposure and some factors affecting exposure were studied. Also, using historical data of asbestos concentrations in asbestos textile plants plus current data, trend of asbestos exposure level could be introduced. Historical exposure level was estimated on the basis of these data. The main results of this study are follows. 1. Average concentration of all six plants surveyed was 1.54 f/cc, and range of those concentrations was 0.03 - 11.58 f/cc. The minimum average concentration was 0.32 f/cc and the maximum was 8.04 f/cc which is four times higher than the Korean standard. A wide difference of exposure level among the workers of different plants was observed. In three plants, the half of all the plants surveyed, their average concentrations exceeded the Korean standard, and those in all the plants exceeded the ACGIH TLV. 2. Among total 56 samples, 22 samples(39%) were in excess of the Korean standard, and 53 samples(95%) were above the ACGIH TLV. Among 32 personal samples, 15 samples(47%) exceeded the Korean standard, and 30 samples(94%) exceeded the ACGIH TLV. Among 24 area samples excluding a few samples collected in office area, seven samples exceeded the Korean standard, and 23 samples( 96%) exceeded the ACGIH TLV. 3. Distributions of concentrations were observed by processes. In weaving, the highest, average concentration was 4.29 f/cc, and range was 2.61 - 11.58 f/cc. In spinning, average concentration was 2.22 f/cc, and range was 0.41 - 8.93 f/cc. In carding, average concentration was 1.98 f/cc, and range was 0.23 - 10.93 f/cc, In twisting, average concentration was 1.65 f/cc, and range was 0.21 - 9.83 f/cc. In mixing, the lowest, average concentration was 0.48 f/cc, and range was 0.22 - 1.20 f/cc. 4. All the samples from basic processes of asbestos textile plants were above the ACGIH TLV. Nineteen samples(45%) out of all these 42 samples exceeded Korean standard. Fourteen samples(58%) of total 24 personal samples, and five samples(28%) of total 18 area samples exceeded the Korean standard. Considering processes, all the samples in weaving process exceeded the Korean standard and 50 did 54% of those in spinning, 40% in carding, and 27% in twisting. 5. Trend of decreasing asbestos concentrations in asbestos textile plants was observed by time. 6. Asbestos concentrations in asbestos textile plant in 1975 were estimated to be 11.0 - 92.4 f/cc.

• Korean Journal of Ecology and Environment
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• v.38 no.4 s.114
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• pp.439-444
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• 2005

The environmental quality of the middle-reach of the Yahagi River has deteriorated in recent years. The nutrient dynamics within the reach were investigated to explain the changes. Seasonal pattern of $NO_3\;^--N$ concentration tended to stay low from April or May through July or August and then increased till winter or early spring, although there were peaks during high flow periods in mid-September, 2000 and late-August, 2001. No clear seasonal changes were observed in $PO_4\;^{3-}-P$ concentration. In the bimonthly records from 1980-2002, the DIN concentrations on January and March were higher than other months whereas the average daily flows on January and March were lower than they were in other months. The mean DIN concentration showed a high negative correlation with the median of average daily flow. In the past 50 years, the average concentration of DIN (excluding nitrite) was 0.21 mg $L^{-1}$ in 1952-1953. The concentration was about twice this high around 1980, and it is about three times this high at present. On the other hand, the average concentration of $PO_4\;^{3-}-P$ was below the limit of detection in 1952-53. However, it increased to almost 0.03 mg $L^{-1}$ around 1980, then decreased to approximately 0.016mg $L^{-1}$ at present. Our results suggest that the increasing DIN concentration is one of the causes of environmental change in the Yahagi River. We conclude that controlling the DIN concentration is essential for improving the river environment.

• Journal of Environmental Science International
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• v.7 no.2
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• pp.157-164
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• 1998

preliminary study on the chemical compositions of forty seven precipitations from March 1994 to May 1995 In Yeoncheon-gun, which Is adjacent to the southern boundary of demilitarized zone (DMZ) in the northernmost tip of Kyunggi Province has been Performed. The metal cation and anion concentrations were measured by atomic absorption spectrometer and ion chromatography, respectively. pH/lon meter and direct nesslerization method were used for the concentration measurements of $H^+$ ion and $NH_46+$ ions, respectively Based on the data, the quantitative orders of the cation and anion average concentrations were $Ca^{2+}>NH_4^+>Na^+>K^+>Mg^{2+}>H^+ and SO_4^{2+}>Cl^-> NO_3^-$, respectively..The ratio of average total anion concentration to average total cation concentration was 0.97. The average pH value of the precipitations was 5.60. These results, correlation coefficients between the ion concentrations, and monthly variations of pH value and precipitation amount are used for chemical analysis on the environmental Pollution and Pollutant sources In Yeoncheon-gun of Kyunggi province near DMZ.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.3
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• pp.486-492
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• 2018

Black carbon concentrations were measured along the altitude at various locations using a drone coupled with a small black carbon detector. The measurement locations are Eunseok Mountain, downtown, four places in KOREATECH campus, Byeongcheon, Cheonan, Chungcheongnam-do, and Chungbu Expressway in Ochang-eup, Cheongju, Chungcheongbuk-do. The average concentration of black carbon measured in Eunseok Mountain was $1.64{\mu}g/m^3$ and the average concentration near the Chungbu Expressway was measured to be $3.86{\mu}g/m^3$. The average concentrations of four places inside campus ranged from 1.37 to $2.67{\mu}g/m^3$. The concentration of black carbon at all places tended to be slightly decreased according to the altitude, but the influence of pollution source, geometry, wind speed, and wind direction are thought to be larger than the effect of altitude. Effect of air flow caused by drone flight on the measurement of black carbon were investigated and it resulted in that the measurement of BC concentration was affected by less than 5%.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.1
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• pp.55-66
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• 1996

One-hour average concentrations of ground-level ozone from around 80 monitoring stations in Korea during 1991 to 1993 were analyzed to examine characteristics of the ozone concentration variations. Two types of variations were observed: one was for the Capital area typified by Kwanghwmun, and the other was for the south and east seashore region typified by Tongkwangyang. In the Capital area including Seoul, Inchon, Kyonggi-do and Chunchon, mean daily 1-hout maximum was the highest in June following high monthly averages in spring. But frequent precipitation prevented further rise of daily maximum in July and August even though there were frequent episodes of high concentration exceeding 100ppb. In the south and east seashore region, average concentration was the highest throughout the year, and daily maximum and minimum simultaneously changed owing to small contributions from photochemical reactions. The typical annual variation was spring peak, summer down, and fall rise. Spring peak accompanied an usual observations of background variations at remote sites in the Northern Hemisphere. Riess of average and daily maximum with lower daily minimum in fall were attributable to photochemical reactions.

• Korean Journal of Materials Research
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• v.24 no.6
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• pp.277-284
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• 2014

Using the spray pyrolysis process, nano-sized cobalt oxide powder with average particle size below 50 nm was prepared from cobalt chloride solution. The influences of the raw material solution on the properties of the powder formed examined. When the concentration of Co was low(20 g/L), the average particle size of the powder formed was roughly 20 nm, and the cohesion between these particles was significantly strong. When the concentration of Co increased to 100 g/L, the droplets nearly failed to exist in circular form and reflected a severely divided form. Furthermore, the average size of the particles formed was roughly 40 nm, and the particles reflected a polygonal form. When the solution was increased to nearly saturation level (Co at 200 g/L), the particle size distribution reflected significant unevenness due to severe droplet division while the surface also reflected significant unevenness. Furthermore, the average size of the particles formed increased significantly to 70 nm. The results of XRD analysis showed that the strength of the peaks reflected very little change when the concentration of Co was increased from 20 g/L to 50 g/L. Alternatively, when the concentration was increased to 100 g/L, the strength of the peaks increased compared to when the concentration was 50 g/L. However, when the concentration was increased to 200 g/L, the strength of the peaks failed to reflect significant change compared to when the concentration was 100 g/L. The specific surface area dramatically decreased by 30 % when the concentration of Co was increased from 20 g/L to 50 g/L. Alternatively, when the concentration of Co the solution increased to 100 g/L, the specific surface area decreased by roughly 15 %. Furthermore, when the concentration of Co was increased to nearly saturation level(200 g/L), the specific surface area decreased by roughly 35%.

• Journal of Environmental Health Sciences
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• v.31 no.1
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• pp.94-98
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• 2005

This study was carried out to provide radon concentration and exposure in building. The average radon concentrations of building was measured 1.37 pCi/L in basement, 0.95 pCi/L in 1st layer, 0.74 pCi/L in 2nd layer, 0.56 pCi/L in 3rd layer, and 0.4 pCi/L in 4th layer, respectively. The average radon concentration of basement was measured the higher than any other stairs. Daily average distribution of radon concentrations in building shown that radon concentrations measured in morning at 8hr was the highest value. Monthly average distribution of radon concentrations shown 0.28 ${\pm}$ 0.17 pCi/L in April and 0.82 pCi/L in December that was the highest value. The average concentrations of radon was measured 0.38pCi/L in spring. 0.44 pCi/L in summer, 0.53 pCi/L in autumn, and 0.67 pCi/L in winter, respectively. This result shown that the average concentrations of radon in winter was the higher than any other seasons. That reasons was supposed that effect of number of exchanges and using air conditions was the higher in summer than winter.

• Journal of Environmental Health Sciences
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• v.46 no.3
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• pp.245-255
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• 2020

Objective: The present study analyzed domestic and overseas academic journals to understand the research status and characteristics of radon concentration distribution in Korea in accordance with environmental conditions. Methods: As part of the meta-analysis, pooled average concentration was calculated using an inverse variance-weighted average of the arithmetic means and standard deviations among the investigated values. Using the obtained pooled average concentration, a Monte-Carlo simulation was performed to increase the reliability of the occurrence possibility of the calculated concentration distribution. A total of 38 research articles were selected, including 27 articles published in domestic academic journals and 11 articles published in foreign academic journals. Results: The comparison results showed differences in radon concentration distribution in accordance with regional and topographical characteristics. Conclusion: Currently, even though research into radon is steadily picking up the pace in Korea much remains to be done. Additional research is thus needed to establish a baseline for radon emissions in Korea.