• Safety and Health at Work
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• v.8 no.3
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• pp.237-245
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• 2017

Background: Solar furnaces are used worldwide to conduct experiments to demonstrate the feasibility of solar-chemical processes with the aid of concentrated sunlight, or to qualify high temperature-resistant components. In recent years, high-flux solar simulators (HFSSs) based on short-arc xenon lamps are more frequently used. The emitted spectrum is very similar to natural sunlight but with dangerous portions of ultraviolet light as well. Due to special benefits of solar simulators the increase of construction activity for HFSS can be observed worldwide. Hence, it is quite important to protect employees against serious injuries caused by ultraviolet radiation (UVR) in a range of 100 nm to 400 nm. Methods: The UV measurements were made at the German Aerospace Center (DLR), Cologne and Paul-Scherrer-Institute (PSI), Switzerland, during normal operations of the HFSS, with a high-precision UV-A/B radiometer using different experiment setups at different power levels. Thus, the measurement results represent UV emissions which are typical when operating a HFSS. Therefore, the biological effects on people exposed to UVR was investigated systematically to identify the existing hazard potential. Results: It should be noted that the permissible workplace exposure limits for UV emissions significantly exceeded after a few seconds. One critical value was strongly exceeded by a factor of 770. Conclusion: The prevention of emissions must first and foremost be carried out by structural measures. Furthermore, unambiguous protocols have to be defined and compliance must be monitored. For short-term activities in the hazard area, measures for the protection of eyes and skin must be taken.

• Atmosphere
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• v.25 no.1
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• pp.169-177
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• 2015

Vertical distribution of particle mass concentrations was estimated from 8-year elastic-backscatter lidar and sky radiometer data, and from ground-level PM10 concentrations measured in Seoul. Lidar ratio and mass extinction efficiency were determined from aerosol optical depth (AOD) and ground-level PM10 concentrations, which were used as constraints to estimate particle mass concentration. The mean lidar ratio (with standard deviation) and mass extinction efficiency for the entire 8-year study period were $60.44{\pm}23.17$ sr and $3.69{\pm}3.00m^2g^{-1}$, respectively. The lidar ratio did not vary significantly with the ${\AA}ngstr{\ddot{o}}m$ exponent (less than ${\pm}10%$); however, the mass extinction efficiency decreases to $1.82{\pm}1.67m^2g^{-1}$ (51% less than the mean value) when the ${\AA}ngstr{\ddot{o}}m$ exponent is less than 0.5. This result implies that the particle mass concentration from lidar measurements can be underestimated for dust events. Seasonal variation of the particle mass concentration estimated from lidar measurements for the boundary layer, was quite different from ground-level PM10 measurements. This can be attributable to an inhomogeneous vertical distribution of aerosol in the boundary layer.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.1
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• pp.155-163
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• 2010

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on-board the NASA's Terra spacecraft provides along-track digital stereo image data at 15m resolution with a base-height ratio 0.6. Automated stereocorrelation procedure was implemented using the ENVI 4.1 software to derive DEMs with $15m{\times}15m$ in 43km long and 50km wide area using the ASTER stereo images. The accuracy of DEMs was analyzed in comparison with those which were obtained from digital topographic maps of 1:25,000 scale. Results indicate that RMSE in elevation between ${\pm}7$ and ${\pm}20m$ could be achieved. Excluding cloud, water and building areas as the factors which make RMSE value exceeding 10m, the accuracy of DEMs showed RMSE of ${\pm}5.789m$. Therefore for the purpose of elevating accuracy of topographic information, we intended to detect the cloud areas and shadow areas by a landcover classification method, remove those areas on the ASTER DEM and then replace with those areas detached from the cartographic DEM by band math.

• Journal of the Korean Geographical Society
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• v.35 no.5
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• pp.745-754
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• 2000

Both Geographic Information System and Remote Sensing fields have been nearly neglected or ignored by historical geographers.This paper intends to show the potentiality of satellite images of various spatial reslutions to explore and to express themes of historical geography. Old Chinese maps and atlas were also used to relate the digital values and historical facfors. Advanced Very High Resolution Radiometer data might be used as a real image for a contintal scale to show changes in coastal shoreline. Landsat Thematic Mapper Imagery of Beijing showed some of boundaries of old palace. Finally IKONOS images of one meter resolution showed detailed information of landcover and landuse of the City, Beijing. The potential capability and limitation to apply satellite imagery in application of historical geography are also discussed.

• The Journal of Engineering Geology
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• v.26 no.1
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• pp.23-32
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• 2016

This study evaluates landslide susceptibility using statistical analysis by SVM (support vector machine) and the illite index of clay minerals extracted from ASTER(advanced spaceborne thermal emission and reflection radiometer) imagery which can be use to create mineralogical mapping. Landslide locations in the study area were identified from aerial photographs and field surveys. A GIS spatial database was compiled containing topographic maps (slope, aspect, curvature, distance to stream, and distance to road), maps of soil properties (thickness, material, topography, and drainage), maps of timber properties (diameter, age, and density), and an ASTER satellite imagery (illite index). The landslide susceptibility map was constructed through factor correlation using SVM to analyze the spatial database. Comparison of area under the curve values showed that using the illite index model provided landslide susceptibility maps that were 76.46% accurate, which compared favorably with 74.09% accuracy achieved without them.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.1
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• pp.97-109
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• 2007

Vertical distribution and optical properties of atmospheric aerosols above the Korean peninsula are quite important to estimate effects of aerosol on atmospheric environment and regional radiative forcing. For the first time in Korea, vertical microphysical properties of atmospheric aerosol obtained by inversion algorithm were analyzed based on optical data of multi-wavelength Raman lidar system developed by the Advanced Environmental Monitoring Research Center (ADEMRC), Gwangju Institute Science and Technology (GIST). Data collected on 14 June 2004 at Gwangju ($35.10^{\circ}N,\;126.53^{\circ}E$) and 27 May 2005 at Anmyeon island ($36.32^{\circ}N,\;126.19^{\circ}E$) were used as raw optical data for inversion algorithm. Siberian forest fire smoke and local originated haze were observed above and within the height of PBL, respectively on 14 June 2004 according to NOAA/Hysplit backstrajectory analysis. The inversion of lidar optical data resulted in particle effective radii around $0.31{\sim}0.33{\mu}m$, single scattering albedo between $0.964{\sim}0.977$ at 532 nm in PBL and effective radii of $0.27{\mu}m$ and single scattering albedo between $0.923{\sim}0.924$ above PBL. In the case on 27 May 2005, biomass burning from east China was a main source of aerosol plume. The inversion results of the data on 27 May 2005 were found to be particle effective radii between $0.23{\sim}0.24{\mu}m$, single scattering albedo around $0.924{\sim}0.929$ at 532 nm. Additionally, the inversion values were well matched with those of Sun/sky radiometer in measurement period.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.4
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• pp.242-246
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• 2017

In this study, it was investigated about optical simulation in high brightness and high uniformity general lighting using glass light guide plate. And we adopt edge-light emission type light plate. Edge-light type lighting has been used LCD application, especially note PC or smart phone backlight unit. Because it had the good properties such as slim shape and light weight. We thought this type was suitable for general lighting application such as wall attached type or ceiling mount type. But many of edge-light type lighting had problems. It called slanted output light rays. That was main key parameter how could control the direction of output light rays. We investigated the solution of this problems, using ray tracing method, we recognized the major fact of the solution relied on the geometric structure of diffusing dot shape. We set the conditions of aspect ratio in diffusing dot shape such as 0.5 to 1. And, at first, we designed diffusing dots shape based on the results of optical simulation and made specimen. as above condition, and acquired good result in confirming dots shape such as the value of the output rays's peak angle was around 75 degrees. And good light distribution characteristics were measured by slated spectro-radiometer. It was shown that the effective ways of designing light distribution characteristics using optical simulation such as ray tracing linear method for making general lighting using glass light guide plate.

• The Journal of Korean Physical Therapy
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• v.18 no.3
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• pp.79-87
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• 2006

Purpose: The present study purposed to examine induced characteristic or erythema and safety by medium wave ultra violet(UVB) lamp. Methods: We compared sunshine and UVB lamp using spectroradiometer and UV radiometer. For measuring sunshine irradiation, we used spectoradiometer and detected from 8 to 18 o'clock every each hour on the beach, playground and rooftop of a 5 story building. The subjects for erythema examination were 5 healthy subjects who have no pathologic history of photosensitivity reaction, psoriasis and vitiligo. They were exposed to UVB radiation at the abdominal area for 2 hours and after irradiation, we observed the change of skin color every 12 hours over a period of 1 week. Results: Between sunshine and UVB lamp, sunshine had higher data on the chromaticity coordinates, dominant and peak wavelength, bandwidth and purity than the UVB lamp but on the color temperature, brightness the UVB lamp had higher data than the sunshine. In comparison of sunshine and UVB lamp, UVB lamp irradiated constantly such as $3.9-4.4{\mu}W/cm^2$ at a distance of 100cm between bed and lamp which was same as early morning irradiation on the sunshine. The erythema didn't appear to any subject. Conclusion: This results suggest that the UVB lamp has lower irradiance as much as early sunshine. Therefore the UVB lamp had no influence of inducing erythema at a distance of 100cm between bed and lamp.

• Korean Journal of Remote Sensing
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• v.29 no.2
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• pp.243-251
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• 2013

The optical properties of long-range transported Asian dust were studied by the satellite observations and Sun/sky radiometer measurements from the Aerosol Robotic Network(AERONET) in Northeast Asia. The movement of Asian dust from source regions to downwind areas was tracked by the Ozone Monitoring Instrument(OMI) derived aerosol product imagery. The optical properties of Asian dust were classified for geographical locations, which are source regions such as deserts area in Dunhuang and Inner Mongolia, downwind areas such as Yulin and Beijing, and long-range transported regions such as Korea(Anmyon and Gosan) and Japan(Noto). In general, relatively higher aerosol mass loadings with larger aerosol particles at desert regions were found. Aerosol Optical Depth(AOD) decreased significantly in downwind areas and long-range transported areas, which was accompanied by increased Angstrom exponents. This indicates the effects of aerosol mixing with various pollutants during transport of Asian dust plume on aerosol optical properties. Moreover, relatively high Single-Scattering Albedo(SSA) at 440 nm values ranging from 0.90 - 0.96 and increasing tendency of SSA with wavelength were observed at source region. The spectral dependence of SSA decreased during long-range transport.

• Journal of the korean society of oceanography
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• v.39 no.1
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• pp.26-34
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• 2004

The evolution of intricate and striking patterns of suspended sediments (SS), which are created by certain physical dynamics in the East China and Yellow Seas, has been investigated using satellite ocean color imageries and vertical profiles of particle attenuation and backscattering coefficients. The structure of these patterns can reveal a great deal about the process underlying their formation. Sea surface temperature (SST) analyzed from the Advanced Very High Resolution Radiometer (AVHRR) thermal infrared data were used to elucidate the physical factors responsible for the evolution of suspended sediment patterns in the East China Sea. The concomitant patterns of suspended sediments were tracked from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) ocean color data. The detailed examination about these patterns gave birth to the definition of the evolution of suspended sediments (SS) into four stages: (1) Youth or Infant stage, (2) Younger stage, (3) Mature stage, and (4) Old stage. We describe about the three directional forces of the tidal currents, ocean warm currents and estuarine circulations that lead to occurrence of various stages of the evolution of suspended sediments that increase turbidity at high levels through out the water column of the inner and outer shelf areas during September to April. The occurrence of these four stages could be repeatedly observed. In contrast, vertical profiles of the particle attenuation ($c_{p}$) and backscattering ($b_{bp}$) coefficients displayed obvious patterns of the propagation of suspended sediment plume from the southwestern coastal sea that leads to eventual collision with the massive sediment plume originating from the Yangtze banks of the East China Sea.