• Applied Chemistry for Engineering
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• v.18 no.3
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• pp.239-244
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• 2007

For the simultaneous methane recovery and $CO_2$-stripping, we have been developed dual vent auto circulation bubble lift column reactor, and evaluate optimum conditions for monoethanolamine (MEA) solutions as a $CO_2$ absorbent. At the 5 wt% MEA solution, we investigated the pH change during $CO_2$-stripping and absorption reaction, $CO_2$-stripping rate with reaction time, methane recovery efficiency for various inflow rates of air, $CO_2$-stripping rate for flow liquid over flow height, and $CO_2$-stripping dependency on the temperature of absolvent solutions. The suggested optimum conditions for $CO_2$ recovery with MEA in the dual vent auto circulation bubble lift column reactor were 40 mm over flow liquid height, 1.5 L/min of air inflow rate, and $25^{\circ}C$ of absorbent solution temperature.

• Journal of Environmental Science International
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• v.22 no.10
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• pp.1263-1271
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• 2013

Graphene oxide (GO)-titania composites have emerged as an attractive heterogeneous photocatalyst that can enhance the photocatalytic activity of $TiO_2$ nanoparticles owing to their potential interaction of electronic and adsorption natures. Accordingly, $TiO_2$-GO mixtures were synthesized in this study using a simple chemical mixing process, and their heterogeneous photocatalytic activities were investigated to determine the degradation of airborne organic pollutants (benzene, ethyl benzene, and o-xylene (BEX)) under different operational conditions. The Fourier transform infrared spectroscopy results demonstrated the presence of GO for the $TiO_2$-GO composites. The average efficiencies of the $TiO_2$-GO mixtures for the decomposition of each component of BEX determined during the 3-h photocatalytic processes were 26%, 92%, and 96%, respectively, whereas the average efficiencies of the unmodified $TiO_2$ powder were 3%, 8%, and 10%, respectively. Furthermore, the degradation efficiency of the unmodified $TiO_2$ powder for all target compounds decreased during the 3-h photocatalytic processes, suggesting a potential deactivation even during such a short time period. Two operational conditions (air flow entering into the air-cleaning devices and the indoor pollution levels) were found to be important factors for the photocatalytic decomposition of BEX molecules. Taken together, these results show that a $TiO_2$-GO mixture can be applied effectively for the purification of airborne organic pollutants when the operating conditions are optimized.

• Journal of Environmental Science International
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• v.21 no.5
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• pp.563-572
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• 2012

Unlike water applications, the photocatalytic technique utilizing light-emitting-diodes as an alternative light source to conventional lamp has rarely been applied for low-level indoor air purification. Accordingly, this study investigated the applicability of UV-LED to annular-type photocatalytic reactor for removal of indoor-level benzene and toluene at a low concentration range associated with indoor air quality issues. The characteristics of photocatalyst was determined using an X-ray diffraction meter and a scanning electron microscope. The photocatalyst baked at $350^{\circ}C$ exhibited the highest photocatalytic degradation efficiencies(PDEs) for both benzene and toluene, and the photocatalysts baked at three higher temperatures(450, 550, and $650^{\circ}C$) did similar PDEs for these compounds. The average PDEs over a 3-h period were 81% for benzene and close to 100% for toluene regarding the photocatalyst baked at $350^{\circ}C$, whereas they were 61 and 74% for benzene and toluene, respectively, regarding the photocatalyst baked at $650^{\circ}C$. As the light intensity increased from 2.4 to 3.5 MW $cm^{-1}$, the average PDE increased from 36 to 81% and from 44% to close to 100% for benzene and toluene, respectively. In addition, as the flow rate increased from 0.1 to 0.5 L $min^{-1}$, the average PDE decreased from 81% to close to zero and from close to 100% to 7% for benzene and toluene, respectively. It was found that the annular-type photocatalytic reactor inner-inserted with UV-LEDs can effectively be applied for the decomposition of low-level benzene and toluene under the operational conditions used in this study.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.581-582
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• 2005

In order to apply the discharge plasma processing. to industrial areas, the control of the chemical reaction mechanism is necessary. The hybrid plasma reactor was designed for the effective treatment of wastewater and hazardous volatile organic substances. This plasma reactor was similar to the barrier discharge, and surface discharge on the dielectric surface was propagated to the water surface strongly for the heterogeneous chemical reaction at the interface between the working gas and the water surface. The discharge emission in this discharge reactor was mainly $N_2$ second positive band in the case of $N_2$ or air gas atmosphere, and intensities from OH radicals in Ar gas atmosphere were stronger than in $N_2$ or air gas atmosphere. From this result, it is necessary to apply Ar gas for the effective generation of OH radicals in this plasma reactor.

• Journal of People, Plants, and Environment
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• v.23 no.6
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• pp.647-654
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• 2020

Background and objective: Particulate matter (PM) is one of the serious environmental problems and threatens human health. Plants can clean the air by removing PM from the atmosphere. This study was carried out to investigate the PM removal efficiency of 12 species of woody plants. Methods: Actinidia arguta, Dendropanax morbiferus, Fraxinus rhynchophylla, Parthenocissus tricuspidata, Pittosporum tobira, Rhaphiolepis indica, Rhapis, Salix integra, Salix koreensis, Schisandra chinensis, Viburnum odoratissimum var. awabuki, and Vitis coignetiae were used as plant material. Six 15 cm (D) pots were placed in an acrylic chamber of 800 (D) × 800 (W) × 1000 (H) mm. The LED panel was used as a light source. The reduction of PM10, PM2.5, and PM1 for 300 minutes after the injection of PM was automatically measured. Results: The leaf area and the amount of PM in the chamber showed a negative correlation. 12 species of plants were compared by dividing the plants into 3 groups according to their characteristics: vines, trees, and shrubs and small trees. In the vine plant group, the averages of PM10, PM2.5, and PM1 were 7.917%, 8.796%, and 30.275%, respectively. In the shrubs and small trees group, the average of PM10, PM2.5, and PM1 were 10.142%, 11.133%, and 36.448%, respectively. In the trees group, the average of PM10, PM2.5, and PM1 were 11.475%, 12.892%, and 40.421%, respectively. When the initial concentration was 100%, PM10, PM2.5, and PM1 of Viburnum odoratissimum var. awabuki with the largest leaf area were 5.6%, 6.3%, and 21.0% after 5 hours, respectively, the best results among 12 species of plants. Conclusion: The vine plant group was more effective in removing PM than the other two groups. In the tree groups, the fact that the leaf development was relatively inactive at a plant height of 30 cm was considered to have an effect on the removal of particulate matter.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.175.1-175.1
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• 2016

In recent, tract infections such as atopic dermatitis, allergic rhinitis and a respiratory disease are increasing, giving rise to the atmospheric pollution, inflow of micro-size dust and side effect of humidifier disinfectant. In this context, the environment-friendly technology is required to eliminate airborne pathogens. We propose solution of the previous problems, making use of Radical Mist Generator (RMG). Existing technologies of air purification using a gas discharge produce harmful substances such as ozone, NOx, etc. However, the RMG uses a pure water as a plasma forming material. The RMG sprays the water mist, which contains reactive radicals to sterilize microorganisms. RMG is comprised of a power supply, plasma electrodes and a nozzle. In order to analyze the electrical characteristic and concentrations of reactive radicals, we employ an oscilloscope and a titration method. To test the sterilization effect of RMG, we used E.coli. We confirmed that E.coli was killed over 90%. Eventually, we expect that RMG can be promising tool for a purified system.

• Journal of Sericultural and Entomological Science
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• v.43 no.1
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• pp.41-48
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• 2001

The purification, dissolution and powdering of stained waste silk obtained from weaving and dyeing process were studied for the surface modification of textile fabric and plastic materials. The whiteness of stained waste silk could be improved through degumming and bleaching with sodium hydrosulfite. The water-soluble fibroin solution can be obtained by dissoving the degummed waste silk in a boiling solution of 50% calcium chloride for 60 minutes. The salts and heavy metals contained in fibroin solution were removed by electric dialysis, wool fiber filtration and gel filtration chromatography. The fibroin powder was prepared by using a fine grinder after the alkali treatment for weakening the silk fiber. The fine fibroin powder of particle size around 30 ㎛ was obtained with a ultra fine-mill, while it was finer below 10 ㎛ with a ball-mill. The dissolved or powdered silk was applied to the surface of fabric with addition of the binder (a urethane resin). The moisture content of polyester and nylon fabrics treated with the silk solution was improved due to hygroscopic property of silk. The fine fibroin powder mixed with the binder ws coated on the surface of synthetic film by use of the air pressed sprayer. It was revealed that the hygroscopicity as well as the softness of fibroin powder coated film was much improved. Therefore, it is thought that the fine silk fibroin powder is applicable as an coating agent for the surface modification of plastic and synthetic leather.

• New & Renewable Energy
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• v.6 no.2
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• pp.27-32
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• 2010

Low Calorific Gas Turbine (LCGT) has been developed as a next generation power system using landfill gas (LFG) and biogas made from various organic wastes, food Waste, waste water and Livestock biogas. Low calorific fuel purification by pretreatment system and carbon dioxide fixation by green house system are very important design target for the optimum applications of LCGT. Main troubles of Low Calorific Gas Turbine system was derived from the impurities such as hydro sulfide, siloxane, water contained in biogas. Even if the quality of the bio fuel is not better than natural gas, LCGT may take low quality gas fuel and environmental friendly power system. The mechanical characterisitics of LCGT system is a high energy efficiency (>70%), wide range of output power (30 kW - 30 MW class) and very clean emission from power system (low NOx). A green house has been designed for four different carbon dioxide concentration from ambient air to 2000 ppm by utilizing the exhaust gas and hot water from LCGT system. LCGT is expected to contribute achieving the target of Renewable Portfolio Standards (RPS).

• Korean Journal of Agricultural and Forest Meteorology
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• v.4 no.4
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• pp.237-247
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• 2002

Air pollution by acid pollutants is problematic in the whole world. Water acidification has already been deteriorating the forest ecosystem. This study was conducted to analyze the acidity and chemical composition of the open precipitation and throughfall at forests with various geographic locations in Korea. The results of this study are as follows; The open precipitation pH was lowest in Seochun. The throughfall pH showed some buffering capacity in only Quercus mongolica stands. In Pinus rigida(Shingal and Seochun) stands, there was little difference from the open precipitation. Chemical composition of the open precipitation for each sampling site showed that $Ca^{2+}$, N $H_{4}$$^{+}$ and S $O_{4}$$^{2-}$ concentrations had higher value than other ions, and except these ions, the small quantity of ions showed different properties to each site. Changes of ion concentrations in the throughfall showed a tendency to increase. ion concentrations of the throughfall increased with washout and nutrient leaching from the trees. In conclusion, the influence was extended to the pure zone, and the frequency of acid rain is increasing. But, if the deposition of pollutants exceeds the capacity of purification, it would damage forest ecosystem. Further investigations are necessary to identify tolerant tree species to acid pollutants.nts.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.769-772
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• 2005

The river environments of many streams in korea have been deteriorate through the rapid industrialization and urbanization since the 1960s. In Germany and Japan, on the other hand, much efforts on the research and project have been made for the restoration of the deteriorated streams to close-to-nature. in order to restore the deteriorated streams, therefore, it is necessary to investigate such advanced technologies and materials. In view of this requirement, various research paths are being taken focusing on coarse aggregates to make multi-functional porous concrete having continuous voids so as to improve water and air permeability, acoustic absorption, water purification, and applicability to vegetation. The Purpose of this study is to investigate the method for recovery of the environment in the streams area using porous concrete block. the porous concrete block applies for test in the cheonggae-cheon have been monitored planting during six month. after 6 months, plant grows flourishing and reconstructed in state such as nature rivers.