• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.6
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• pp.561-567
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• 1987

The purpose of this study was to find out the removal capacity of harmful ammonia by different filter media in the submerged biological filters in a given space of chamber. Four materials, pile cloth, corrugated skylight roofing plate, embossed plastic plate, and gravel, were used as the experimental filter media. Each filter medium was placed in two aquariums, each aquarium measuring $90cm\times60cm\times60cm\;(depth)$. Under the normal operating condition, the average of mean ammonia removal rates during the first and second functioning periods by each filter material which occupied tile space in the filter chamber (aquarium) was as follows: 1. Pile cloth: $8.381\;g{\cdot}m^{-3}.\;day^{-1}$ 2. Corrugated skylight roofing plate: $7.834\;g{\cdot}m^{-3}.\;day^{-1}$ 3. Embossed plastic plate: $7.797\;g{\cdot}m^{-3}.\;day^{-1}$ 4. Gravel: $7.051\;g{\cdot}m^{-3}.\;day^{-1}$ Thus, there were no significant differences between the media, but at the time of practical application of these materials, some other factors such as investment cost, easiness for the removal of excess detritus accumulated in tile interstices of filter media, etc. should be fallen into consideration. When large units are required, in particular, removal of excess detritus from tile gravel bed is extremely difficult, and in case of pile cloth filters the installation work is much complicated and a problem in supporting the structure when drained also exists. In these respects, corrugated skylight roofing plate and embossed plastic plate seem to be more optimal, but again in practice the local situation for the availability and the price of the materials should be rechecked and the fitness of tile materials in the particular filter chambers under use or under consideration for construction must be taken into account.

• Atmosphere
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• v.21 no.1
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• pp.57-67
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• 2011

Aerosol lidar ratio (extinction-to-backscatter ratio) at 532 nm was determined using 4-year measurements of elastic-backscatter lidar and sky radiometer at Seoul National University of Seoul, Korea. The mean lidar ratio (with standard deviation) based on 4 years of measurements is found to be $61.7{\pm}16.5$ sr, and weak seasonal variations are noted with a maximum in JJA ($68.1{\pm}16.8$ sr) and a minimum in DJF ($57.2{\pm}17.9$ sr). The lidar ratios for clean, dust, and polluted conditions are estimated to be $45.0{\pm}9.5$ sr, $51.7{\pm}13.7$ sr, and $62.2{\pm}13.2$ sr, respectively. While the lidar ratio for the polluted condition is appears to be consistent with previous studies, clean and dust conditions tend to have larger ratios, compared to previous estimates. This discrepancy is thought to be mainly due to the anthropogenic aerosols existing throughout the year around Seoul, which may cause increased lidar ratios even for clean and dust conditions.

• Journal of the Korean earth science society
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• v.26 no.8
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• pp.790-799
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• 2005

We investigate the optical properties of aerosols over Gongju by an indirect method using the pound measurement, Sky-radiometer. The analysis period is from January to December, 2004. Skyrad. pack.3 is used to estimate the optical properties, such as the aerosol optical thickness (AOT), single scattering albedo (SSA), ${\AA}ngstron$ exponent $({\alpha})$ and size distribution, of aerosols from the ground measured radiance data. And qualify control is applied to minimize the cloud-contaminated data and improve the quality of analysis results. The 12-month average of AOT, ${\alpha}$, and SSA are 0.46, 1.14, and 0.91, respectively. The average volume spectra of aerosols shows a bi-modal distribution, the first peak at fine mode and the second peak at coarse mode. AOT and coarse particles clearly increases while SSA decreases during the Asian dust events. The optical properties of aerosols at Gongju vary with?seasons, but those are not influenced by the wind direction.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.169-178
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• 2000

Perovskite oxide catalysts doped on porous alumina beads are prepared in a citric acid solution. To investigate the applicability of the catalysts to the hot gas cleanup, a series of experiments on the reduction characteristics of $NO_x$ by CO as a reducing agent are carried out in a packed bed reactor containing the catalysts. Parameters tested are the operating temperature and $CO/NO_x$ molar ratio. It is found that mixed complex oxides of $La_{0.5}Sr_{0.5}CoO_3$, $SrAl_{12}O_{19}$ and $LaAl_{11}O_{18}$ are uniformly distributed on the alumina beads. The conversion efficiency of $NO_x$ by CO sharply increases with the operating temperature up to $700^{\circ}C$ and then approaches 100% when $CO/NO_x$ molar ratio is greater than 1.0. The conversion efficiency of $NO_x$ is maintained by over 98% during a continuous operation for 23 hours at $800^{\circ}C$ and space velocity of $10700hr^{-1}$.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.1
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• pp.57-67
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• 2021

The geology of the Iskaycruz project are mainly composed of sedimentary rocks within Cretaceous basin. The basal part is composed up of dark-gray shale, gray sandstone, and clastic rock of Oyon formation interbedded with coal measures. In the folded zone in the eastern part of the survey area, there is Chimu formation that has medium-grained massive and white quarztite. In terms of geological structure, the Iskaykruz region is located in the folded and overthrust zones of the central part of the Occidental Mountains. Ore body was formed by hydrothermal replacement process and consists of zinc, lead, silver, and copper. Stratabound-type deposits are hosted in limestone of Santa formation. It extends 12 kilometers discontinuously from northern Canaypata to southern Antapampa. Irregular iron oxide and sulfide minerals hosted in Santa and Parihuanca formations are observed. The mineralization observed on the surface consist of primary sulfides consisting of sphalerite with galena and chalcopyrite, and iron and manganese oxide produced from oxidation of primary sulfides. Skarn minerals are accompanied by tremolite, garnet, epidote and quartz.

• Proceedings of the Korean Information Science Society Conference
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• 2010.11a
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• pp.11-12
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• 2010

• Proceedings of the Korean Information Science Society Conference
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• 2008.06a
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• pp.5-6
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• 2008

• Proceedings of the Korean Information Science Society Conference
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• 2010.06a
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• pp.21-22
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• 2010

• Proceedings of the Korean Information Science Society Conference
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• 2010.06a
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• pp.15-16
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• 2010

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.450-453
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• 2006

Coupling adjacent building with supplemental damping devices is a developing method of reduced structural response due to wind and seismic excitations. The philosophy is to allow structures, vibrating at different frequencies, to exert control forces upon one another to reduce the overall responses of the system. This paper studies the effect of installing vibration control devices of two high rise building structures(49 stories and 42 stories) connected by sky-bridge. According to the analysis results the use of sky-bridge can be effective in increasing damping ratio of the system.