• Applied Chemistry for Engineering
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• v.22 no.1
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• pp.31-36
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• 2011

Tetrafluoromethane ($CF_4$) has been used as the plasma etching and chemical vapor deposition (CVD) gas for semiconductor manufacturing processes. However, the gas need to be removed efficiently because of their strong absorption of infrared radiation and the long atmospheric lifetime which cause global warming effects. A waterjet gliding arc plasma system in which plasma is combined with the waterjet was developed to effectively produce OH radicals, resulting in efficient destruction of $CF_4$ gas. Design factors such as electrode shape, electrode angle, gas nozzle diameter, electrode gap, and electrode length were investigated. The highest $CF_4$ destruction of 93.4% was achieved at Arc 1 electrode shape, $20^{\circ}$ electrode angle, 3 mm gas nozzle diameter, 3 mm electrode gap and 120 mm electrode length.

• Korean Journal of Remote Sensing
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• v.28 no.4
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• pp.393-407
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• 2012

This study focuses on the correction of topographic effects caused by a combination of solar elevation and azimuth, and topographic relief in single optical remote sensing imagery, and by a combination of changes in position of the sun and topographic relief in comparative analysis of multi-temporal imageries. For the Jeju Island, Republic of Korea, where Mt. Halla and various cinder cones are located, a Landsat 7 ETM+ imagery and ASTER GDEM data were used to normalize the topographic effects on the imagery, using two topographic normalization methods: cosine correction assuming a Lambertian condition and assuming a non-Lambertian c-correction, with kernel sizes of $3{\times}3$, $5{\times}5$, $7{\times}7$, and $9{\times}9$ pixels. The effects of each correction method and kernel size were then evaluated. The c-correction with a kernel size of $7{\times}7$ produced the best result in the case of a land area with various land-cover types. For a land-cover type of forest extracted from an unsupervised classification result using the ISODATA method, the c-correction with a kernel size of $9{\times}9$ produced the best result, and this topographic normalization for a single land cover type yielded better compensation for topographic effects than in the case of an area with various land-cover types. In applying the relative radiometric normalization to topographically normalized three multi-temporal imageries, more invariant spectral reflectance was obtained for infrared bands and the spectral reflectance patterns were preserved in visible bands, compared with un-normalized imageries. The results show that c-correction considering the remaining reflectance energy from adjacent topography or imperfect atmospheric correction yielded superior normalization results than cosine correction. The normalization results were also improved by increasing the kernel size to compensate for vertical and horizontal errors, and for displacement between satellite imagery and ASTER GDEM.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.391-398
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• 2023

This study focuses on the potential for creating spatial and atmospheric effects in small theaters using mobile stage equipment, without being constrained by physical space or theater facilities, for mega musical productions. With the continuous growth of mega musicals in the domestic market, the study analyzes the distribution and sales of musical works in Korea and proposes methods for creating spatial effects in university musical education to facilitate the production of mega musicals in small theaters. The mobile stage equipment is designed based on the principle of the periaktoi, a stage mechanism used in ancient Greek theater and the characteristics of mobile stage equipment used in musicals such as <Notre Dame de Paris> and <Laundry>. The mobile stage equipment is a four-sided column-shaped device, which is applied to the musical <Les Misérables> to derive the potential for creating spatial effects, representing the inner state of characters, and forming the mood of the drama. The study is expected to provide opportunities for performing mega musical productions in university musical education and to contribute to the development of the musical industry and education. The utilization of mobile stage equipment demonstrates the possibility of producing mega musical productions in small theaters.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.5
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• pp.581-594
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• 2012

The goal of this study is to investigate the effects of the chemical lateral boundary conditions (CLBCs) on Community Multi-scale Air Quality (CMAQ) simulations of tropospheric ozone for East Asia. We developed linking tool to produce CLBCs of CMAQ from Goddard Earth Observing System-Chemistry (GEOS-Chem) as a global chemistry model. We examined two CLBCs: the fixed CLBC in CMAQ (CLBC-CMAQ) and the CLBC from GEOS-Chem (CLBC-GEOS). The ozone fields by CMAQ simulation with these two CLBCs were compared to Tropospheric Emission Spectrometer (TES) satellite data, ozonesonde and surface measurements for May and August in 2008. The results with CLBC-GOES showed a better tropospheric ozone prediction than that with CLBC-CMAQ. The CLBC-GEOS simulation led to the increase in tropospheric ozone concentrations throughout the model domain, due to be influenced high ozone concentrations of upper troposphere and near inflow western and northern boundaries. Statistical evaluations also showed that the CLBC-GEOS case had better results of both the index of Agreement (IOA) and mean normalized bias. In the case of IOA, the CLBC-GEOS simulation was improved about 0.3 compared to CLBC-CMAQ due to the better predictions for high ozone concentrations in upper troposphere.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.5
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• pp.595-605
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• 2012

Fine particles ($PM_{2.5}$) were collected and analyzed from April 2010 through January 2011 in Chungju to investigate the characteristics of $PM_{2.5}$ and its ionic species. The annual mean concentrations of $PM_{2.5}$, ${SO_4}^{2-}$, $NO_3{^-}$, and $NH_4{^+}$ in the particulate phase were 40.84, 7.61, 7.14 and $3.74{\mu}g/m^3$, respectively. $PM_{2.5}$ concentrations were higher in fall and spring than in winter and summer. The elevated concentrations episodes are the main factor that enhanced the $PM_{2.5}$ concentrations in the fall. Among the major ionic species ${SO_4}^{2-}$ showed the highest concentration, followed by $NO_3{^-}$ and $NH_4{^+}$, $NO_3^-$ exhibited higher concentrations during the winter, but ${SO_4}^{2-}$ and $NH_4{^+}$ were not showed seasonal variation. The high correlations were found among $PM_{2.5}$, ${SO_4}^{2-}$, $NO_3{^-}$ and $NH_4{^+}$ during all seasons except for spring. The evaluation of backward trajectories and meteorological records show that the highest $PM_{2.5}$ concentration levels occurred during W-NW weather conditions, which influenced by the emission sources of China area. The low pollution levels generally occurred during E-S weather conditions, which influenced by the East Sea and south of the Yellow Sea. The elevated $PM_{2.5}$ mass concentrations arouse the concentration of $NO_3{^-}$, but no effects on ${SO_4}^{2-}$ and $NH_4{^+}$.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.5
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• pp.571-580
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• 2012

Epidemiologic studies of air pollution need accurate exposure assessments at unmonitored locations. A land use regression (LUR) model has been used successfully for predicting traffic-related pollutants, although its application has been limited to Europe, North America, and a few Asian region. Therefore, we modeled traffic-related pollutants by LUR then examined whether LUR models could be constructed using a regulatory monitoring network in Metropolitan area in Korea. We used the annual-mean nitrogen dioxide ($NO_2$) in 2010 in the study area. Geographic variables that are considered to predict traffic-related pollutants were classified into four groups: road type, traffic intensity, land use, and elevation. Using geographical variables, we then constructed a model to predict the monitored levels of $NO_2$. The mean concentration of $NO_2$ was 30.71 ppb (standard deviation of 5.95) respectively. The final regression model for the $NO_2$ concentration included five independent variables. The LUR models resulted in $R^2$ of 0.59. The mean concentration of $NO_2$ of elementary schools was 34.04 ppb (standard deviation of 5.22) respectively. The present study showed that even if we used regulatory monitoring air quality data, we could estimate $NO_2$ moderately well. These analyses confirm the validity of land use regression modeling to assign exposures in epidemiological studies, and these models may be useful tools for assessing health effects of long-term exposure to traffic related pollution.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.4
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• pp.45-59
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• 2006

In this study, the effects of the surface topographical characteristics on the meteorological fields are examined in a mesoscale meteorlolgical model. We calculated the direct solar radiation using the illumination angle considering the inclination of topography and tried to find out its effect on meteorological fields. In above experiments, we selected two cases for the clear day and the cloudy day to show the effect of weather and represented the results for two cases. In the correction of the direct solar radiation, the results of two cases indicate that there are obvious differences on the steep Taeback and Soback mountains. And on the time-series analysis the east-facing slope of these mountains receives the more direct solar radiation about $10-60W/m^2$ in the morning hours but lesser in the afternoon hours than the horizontal surface while it is opposite on the west-facing slope. And the results mentioned above are more obvious at clear day. With the same analysis method, at clear day, the surface skin temperature is higher at all hours than that on horizontal surface on the both of slope. At cloudy and rainy day, the surface skin temperature on the east-facing slope is higher in the morning hours but lower in the afternoon hours than that on horizontal surface. But on the west-facing slope, it is higher at all hours than that on horizontal surface. In the two cases, the temperature considering the slope of surface is almost higher than that on the horizontal surface. The wind is stronger than that on the horizontal surface with increasing pressure gradient force according as increasing temperature gradient around the Taeback and the Soback mountains.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.3
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• pp.325-347
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• 2012

Long-term air and weather data monitored during the period of 2000 to 2009 were analyzed to quantitatively estimate the precipitation scavenging and wind dispersion contributions of ambient $PM_{10}$ and $NO_2$ in Korea. Both air pollutants and meteorological data had been respectively collected from 120 stations by the Ministry of Environment and from 20 weather stations by the Korea Meteorological Administrations in all parts of Korea. To stochastically identify the relation between a meteorological factor and an air pollutant, we initially defined the SR (scavenging ratio) and the DR (dispersion ratio) to separately calculate the precipitation and wind speed effects on the removal of a specific air pollutant. We could then estimate the OSC (overall scavenging contribution) and the ODC (overall dispersion contribution) with considering sectoral precipitation and wind speed probability density distributions independently. In this study, the SRs for both $PM_{10}$ and $NO_2$ were generally increased with increasing the amounts of precipitation and then the OSCs for $PM_{10}$ and $NO_2$ were estimated by 22.3% and 15.7% on an average in Korea, respectively. However, the trend of the DR was quite different from that of SR. The DR for $PM_{10}$ was increased with increasing wind speed up to 2.5 m/s and further the DR for $NO_2$ showed a minimum in the range of $1<WS{\leq}1.5$. The ODCs for $PM_{10}$ and $NO_2$ were estimated by 14.9% and 1.0% in Korea, respectively. Finally, we have also provided an interesting case study observed in Seoul.

• Asian Journal of Atmospheric Environment
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• v.10 no.1
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• pp.51-56
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• 2016

Particulate matter (PM) in the atmosphere has wide-ranging health, environmental, and climate effects, many of which are attributed to fine-mode secondary organic aerosols. PM concentrations are significantly enhanced by primary particle emissions from traffic sources. Recently, in order to reduce $CO_2$ and increase fuel economy, gasoline direct injected (GDI) engine technology is increasingly used in vehicle manufactures. The popularization of GDI technique has resulted in increasing of concerns on environmental protection. In order to better understand variations in chemical composition of particulate matter from emissions of GDI vehicle versus a port fuel injected (PFI) vehicle, a high time resolution chemical composition of PM emissions from GDI and PFI vehicles was measured at facility of Transport Pollution Research Center (TPRC), National Institute of Environmental Research (NIER), Korea. Continuous measurements of inorganic and organic species in PM were conducted using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The HR-ToF-AMS provides insight into non-refractory PM composition, including concentrations of nitrate, sulfate, hydrocarbon-like and oxygenated organic aerosol, and organic mass with 20 sec time resolution. Many cases of PM emissions during the study were dominated by organic and nitrate aerosol. An overview of observed PM characteristics will be provided along with an analysis of comparison of GDI vehicle versus PFI vehicle in PM emission rates and oxidation states.

• Korean Journal of Remote Sensing
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• v.30 no.6
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• pp.731-742
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• 2014

In this study, we developed a new algorithm which can construct model buildings used as a surface boundary in numerical models using GIS with latitudinal and longitudinal information of building vertices. The algorithm established the outer boundary of a building first, by finding segments passing neighboring two vertices of the building and connecting the segments. Then, the algorithm determined the region inside the outer boundary as the building. The new algorithm overcame the limit that the algorithm developed in the previous study had in constructing concave buildings. In addition, the new algorithm successfully constructed a building with complicated shape. To investigate effects of the modification in building shape caused by the building-construction algorithm on flows and pollutant dispersion around buildings, a computational fluid dynamics model was used and three kinds of building type were considered. In the downwind region, patterns in flow and pollutant dispersion were little affected by the modification in building shape caused. However, because of reduction in air space resulted from the building-shape modification, vortex structure was not resolved or smaller vortex was resolved near the buildings. The changes in flow pattern affected dispersion patterns of scalar pollutants emitted around the buildings.