• Korean Journal of Remote Sensing
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• v.33 no.2
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• pp.135-147
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• 2017

We, for the first time, estimated daily and monthly surface nitrogen dioxide ($NO_2$) volume mixing ratio (VMR) using three regression models with $NO_2$ tropospheric vertical column density (OMIT-rop $NO_2$ VCD) data obtained from Ozone Monitoring Instrument (OMI) in Seoul in South Korea at OMI overpass time (13:45 local time). First linear regression model (M1) is a linear regression equation between OMI-Trop $NO_2$ VCD and in situ $NO_2$ VMR, whereas second linear regression model (M2) incorporates boundary layer height (BLH), temperature, and pressure obtained from Atmospheric Infrared Sounder (AIRS) and OMI-Trop $NO_2$ VCD. Last models (M3M & M3D) are a multiple linear regression equations which include OMI-Trop $NO_2$ VCD, BLH and various meteorological data. In this study, we determined three types of regression models for the training period between 2009 and 2011, and the performance of those regression models was evaluated via comparison with the surface $NO_2$ VMR data obtained from in situ measurements (in situ $NO_2$ VMR) in 2012. The monthly mean surface $NO_2$ VMRs estimated by M3M showed good agreements with those of in situ measurements(avg. R = 0.77). In terms of the daily (13:45LT) $NO_2$ estimation, the highest correlations were found between the daily surface $NO_2$ VMRs estimated by M3D and in-situ $NO_2$ VMRs (avg. R = 0.55). The estimated surface $NO_2$ VMRs by three modelstend to be underestimated. We also discussed the performance of these empirical modelsfor surface $NO_2$ VMR estimation with respect to otherstatistical data such asroot mean square error (RMSE), mean bias, mean absolute error (MAE), and percent difference. This present study shows a possibility of estimating surface $NO_2$ VMR using the satellite measurement.

• Fire Science and Engineering
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• v.16 no.1
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• pp.1-7
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• 2002

Halogen-based fire suppressing agents have environmental problems because they cause the stratospheric ozone depletion and globe warming. Hence, fire suppression system using fine water mist became the center of interest as a substitution of halon. As a study about this, it is in progress to make the optimum droplet size by using water mist nozzles and to improve the extinguishing performance of water mist by using additives. Before this study, the extinguishing time of ethanol and n-heptane pool fire was measured with changing of water mist droplet size, flow density, discharge pressure, and fire size. In this study, on adding the additives to improve physical and chemical extinguishing performance of water mist, the extinguishing performance would evaluate and the optimum condition would find out. As a result, in case of ethanol pan 1 pool fire, the extinguishing time of the water mist by adding of 2.5 wt% NaCl and 0.3% AFFF got shorter 27% and 60% than the pure water mist. Adding of AFFF was to decrease the flame temperature by forming thin film on the fuel surface and to decrease the evaporation of n-heptane fuel. In case of NaCl, alkali salt crystals showed on the flame surface.

• Clean Technology
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• v.12 no.4
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• pp.250-258
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• 2006

CFC compounds such as CFC-113 and 1,1,1-TCE, etc. have been used in various industries due to their excellent chemical stability, thermodynamic characteristics, non-inflammability and anti-corrosiveness. However, in oder to protect the earth environment, "the Montreal Protocol on substances that deplete the ozone layer" was adopted in 1989 for prevention of production and utilization of these CFC compounds and alternative cleaning agent have been required in the industry. The objective of this study is to develop non-aqueous cleaning agents that do not require major change of cleaning system, have excellent cleaning efficiency, are favorable to the environment, are harmless to the human body, and are not generated corrosive materials. In this work, non-aqueous cleaning agents have been formulated with glycol ether series and paraffinic hydrocarbon series with siloxane, and their physical properties and cleaning efficiencies were analyzed and compared with those of regulated materials. As a result of physical properties measurement of the formulated cleaning agents, it is expected that they may have good penetration ability into contaminated materials due to their properties with low density and low surface tension. Measurement of flash point and vapor pressure of the cleaning agents will be helpful for evaluation of their safety and working environment. The experimental results of cleaning flux, solder and grease by the formulated cleaning agents show that their cleaning abilities of soils were good and that there were no residues on the substance after cleaning. Therefore, alternative cleaning agents which have equivalent cleaning ability to regulating materials, good penetration ability and low hazard to human body, have been developed in this work.

• Journal of Marine Life Science
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• v.5 no.2
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• pp.51-57
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• 2020

Disinfection and maintenance of rearing water in aquaculture is an essential element for the prevention of fish diseases. This is especially important in recirculating aquaculture systems (RAS) in which fish are reared at high density using recycled water. In this study, tilapia was reared in two different RAS (one with plasma generator - PW system, another without plasma generator - No PW system). In plasma treated group, UVT% of water was improved clearly, and the number of heterotrophic bacteria decreased significantly after 40 days. Total weight gain of tilapia in PW system was significantly higher, and other growth indicators were also relatively higher although not statistically significant. In addition, the fish in PW system had a 100% survival rate, and there were no histological differences between fish from both systems. Fish did not seem to be affected by the toxicity of ROS. In conclusion, it is expected that plasma water can effectively deactivate fish pathogens and improve the quality of rearing water.

• Journal of Environmental Health Sciences
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• v.50 no.3
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• pp.191-200
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• 2024

Background: Busan is a rapidly industrializing city with many mixed residential and industrial areas. Fine dust emissions from mobile pollution sources such as ships and vehicles are particularly high in Busan. Objectives: This study analyzed the spatial distribution of air pollutants over the past three years and identified the impact of air pollutants through mobile source data in Busan. Methods: We obtained air pollutant data on fine particulate matter (PM₁₀), ultrafine particulate matter (PM_2.5), nitrogen dioxide (NO₂), sulfurous acid gas (SO₂), and ozone (O₃) for the last three years (source: airkorea.or.kr) and analyzed the spatial distribution using SAS 9.4 and Surfer 23. For the mobile pollutant data, we used CCTV data from major intersections in Busan to identify truck and car traffic, and visualized traffic density with QGIS. Results: The analysis of the concentration of air pollutants over three years (2020~2022) showed that all were lower than the annual environmental standards with the exception of PM_2.5. PM₁₀ and PM_2.5 were found to be highly concentrated in the western part of the area, while NO₂ was high in the port area of Busan and SO₂ was high in the western part of the area and near the new port of Busan. In the case of O₃, it was high in the eastern part of the city. The traffic volume of freight vehicles by intersection was concentrated in the West Busan area, and the traffic volume for all cars was also confirmed to be concentrated at "Mandeok Intersection" located in the West Busan area. Conclusions: This study was conducted to determine the relationship between air pollutants emitted from motor vehicles and the distribution of air pollutants in Busan. The spatial distribution of PM₁₀ and PM_2.5 correlates with traffic volume, while high concentrations of SO₂ and NO₂ near the port are associated with ship emissions.