• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.5
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• pp.39-46
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• 2020

This study evaluated the nitrogen oxide (NO_x) removal efficiency by air purification concrete blocks with titanium dioxide (TiO₂). The concrete in the mixtures had a 30% water:cement ratio, to which TiO₂ was added at 0%, 5%, and 10% of cement weight. The compressive strength reduction rate and removal efficiency of NO_x were investigated. The result of the compressive strength test in the study indicated that addition rate of TiO₂ did not lead to signifcant effect. In terms of the average removal efficiency of NO_x, mix No. 1 using a TiO₂ mixing ratio of 0% had a removal efficiency of 0.57% on average; thus, the removal effect w as not significant. For the other samples prepared by mixing, the average removal efficiencies for mix No. 2 (5% TiO₂) were 58.86% and 62.05% for normal and washing surface treatments, respectively, and those of sample No. 3 (10% TiO₂) were 59.94% and 67.61%. mixs No. 4 (5%) and No. 5 (10%), in which TiO₂ diluted with distilled water was sprayed onto the block surface, had an average NO_x removal efficiency of 61.72% and 68.48%, respectively. In terms of NOx removal efficiency, Mixs No. 3 and No. 5 with 10% TiO₂ were better than Mixs No. 2 and No. 4 with 5% TiO₂. In addition, analyzing the NO_x removal efficiency results from the fixing method, it was capable to apply mixing (washing) and the diluted spray methods. Therefore, it was found that the diluted spray method applied in this study can be employed in any manufacture of air purification concrete blocks.

• 한국약용작물학회:학술대회논문집
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• 2008.11a
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• pp.491-492
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• 2008

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.23-27
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• 2012

To make synthetic liquid fuel from biomass such as wood pellet, energy crop and so on, a biomass to liquid (BTL) process by using a biomass gasifier with Fisher-Tropsch (FT) reaction was developed. However $H_2S$, COS and $CO_2$ in syngas from biomass gasifiers resulted in a decrease of the conversion efficiency and the deactivation of the catalyst. To remove acid gases in syngas, a lab-scale methanol absorption tower was developed and the removal characteristics of acid gases were investigated. The methanol absorption tower efficiently removed $H_2S$ and COS with a removal of $CO_2$, so it could be useful process for the BTL process.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.1
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• pp.27-34
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• 2010

In a test duct with closed configuration, particle removal performance of an edge-plate type electrostatic precipitator (ESP) was evaluated at a high flow rate in $CO_2$ rich environments by changing gap distances between collection plates, concentrations of $CO_2$, particle sizes, types of electrodes, and types of power supplies. At the same experimental conditions, collection efficiency of particles with the mean particle size, 300 nm, decreased as the gap distance and $CO_2$ concentration increased because of low electrostatic force and low discharged current. In addition, as the particle size increased, the efficiency increased because of high charging rate of the large particles. With the electrode type which has higher surface area of a discharging plate and with the power supply which applied 25 kHz-pulsed DC voltages, the removal efficiency was high even in rich $CO_2$ condition due to high electrostatic force at the same power consumption.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.11
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• pp.1095-1101
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• 2008

Nonaqueous phase liquids (NAPL) are the continuous source for soil and groundwater contamination. The first objective of the study was to verify the effect of co-injection of cosolvent and air on NAPL removal from soil-column system. The second objective of the study was to investigate the effect of alcohol-partitioning property on the NAPL removal by the co-injection process of cosolvent and air. Enhanced removal of benzene-NAPL by the co-injection process of ethanol and air was also verified within the soilcolumn system. However, the co-injection process of Tert-butanol (TBA) and air showed no enhancement of benzene-NAPL removal. This study found that the viscous pressure of TBA was so higher than the capillary pressure and TBA easily displaced the benzene-NAPL and air present in soil pores. Air of the coinjection process did not work for NAPL removal but hindered NAPL mobilization. NAPL partitioning property and viscous pressure of cosovlent should be considered for application of the co-injection process of cosolvent and air.

• Food Science and Preservation
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• v.6 no.4
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• pp.392-397
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• 1999

The quality changes during the removal of astringecy by CO$_2$gas at 2$^{\circ}C$ and 20$^{\circ}C$ of three varieties of persimmons named 'Tonewase', 'Chungdobanshi' and 'Sagokshi' were examined. Astringency index and tannin content showed rapid decrease at 20$^{\circ}C$ and gradual decrease at 2$^{\circ}C$. All was edible 2days from the removal of astringency at 20$^{\circ}C$, while 'Tonewase' and 'Sagokshi' were edible on 6days and 'Chungdobanshi' on 10days after treatment at 2$^{\circ}C$. Soluble solid contents was decreased a little(1∼3%) during the removal of astringency. Hardness was decreased slowly but, kept over 1.0kg/$\phi$5mm till edible period in all varieties at 2$^{\circ}C$ and 20$^{\circ}C$. The hardness of 'Chungdobanshi' was kept well after the removal of astringency at 2$^{\circ}C$. No noticeable color changes in all varieties during treatment. Injury fruits were noticeable in only 'Tonewase' after the removal of astringency treatment at 2$^{\circ}C$.

• Journal of Korea Society of Waste Management
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• v.35 no.8
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• pp.731-743
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• 2018

This study was performed to test the feasibility of thermophilic ($55^{\circ}$) co-digestion of municipal sewage sludge and food wastes. The management variables of co-digestion were the mixed ratios of municipal sewage sludge and food waste hydraulic retention times (HRTs). During the operation of thermophilic co-digestion, the reactor pH ranged from 7.0 to 7.5 and the reactor alkalinity remained above 3,200 to 4,000 mg/L as $CaCO_3$. The volatile fatty acids concentration increased as the HRT shortened from 20 days to 10 days and the mixture ratio increased to 1:4, but did not reach toxic levels for co-digestion of sewage sludge and food wastes. Methane productivity increased gradually as the organic loading rate increased. Maximum methane productivity reached 1.03v/v-d at an HRT of 10 days and at the mixture ratio of 1:4. The TVS removal efficiency decreased from 70.6% to 58.3% as the HRT shortened from 20 days to 10 days. TVS removal efficiency ranged from 57.0% to 77% during the entire operation. It is likely that thermophilic co-digestion of sewage sludge and food wastes is a very effective method both to environmentally treat food waste and to economically produce gas for energy.

• Journal of Korean Society on Water Environment
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• v.20 no.2
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• pp.104-109
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• 2004

Removal of nutrients from domestic sewage or industrial wastewater is needed to protect surface waters from eutrophication. This research was carried out to remove the nitrogen (N) and phosphorus (P) from the wastewater using the iron oxide obtained from the steel industry and the natural zeolite, respectively. This research was conducted in both batch and continuous systems. The removal efficiency of the nutrients was evaluated in the batch system using the varying concentrations of zeolite and iron oxide added. The removal efficiency of N was 60% at the 8g of zeolite added. In the same condition, the removal efficiencies of N were 76% and 82% at 12g and 16g of zeolite added, respectively. Removal efficiency of P was 80% as 8g of iron oxide was added. The removal efficiency of P was correspondingly increased as the concentration of iron oxide was increased. Continuous column system was also used to evaluate the removal efficiency of N and P by the addition of zeolite and ferric oxide, respectively. Removal efficiencies of N were compared in the mixed packing, two stage, and four stage columns, respectively. The removal efficiencies (80%) of N in the separate packed columns (two and four stages) were higher than the mixed packing column (400%) after 90 hr. Whereas, the removal efficiencies of P were similar to each other in the three columns.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.209-212
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• 2002

Main radionuclides of the soil waste stored in Korea Atomic Energy Research Institute are Co-60 and Cs-137. Moisture content of soil is 12%, pH of soil is 5.8, and content of organic matter is 2.2 %. Radioactive concentrations of the soil particle size of which is less than 0.063mm and soil in the drum surface of which is more than radiation dose rate 0.05mR/hr are higher. Meanwhile, radioactive concentration of soil in the drum surface of which is less than radiation dose rate 0.02 mR/hr are mostly lower. On using the mixing solution of ammonium sulfate and citric acid, 62% Co was removed from soil and 41% Cs was removed. Also, on using the mixing solution of ammonium nitrate and citric acid, 61% Co was removed from soil and 39% Cs was removed, and on using the mixing solution of ammonium potassium oxalate, 36% Co was removed and only 3% Cs was removed. And on using only water, removal efficiency is less than 5%.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.129-132
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• 2003

Silica/SUS composite membranes were prepared for CO removal from products of methanol steam reforming. A support was prepared by coating Ni powder of sub-micron and SiO$_2$ sols of particle size of 500nm and 150nm in turns on a porous stainless steel (SUS) substrate. Silica top layer was coated on the modified support using colloidal sol with nanoparticle. As a result of mixture gas permeation test of silica composite membrane using H$_2$(99%)/CO(1%), CO concentration of 10000 ppm was reduced to under 81 ppm, which is acceptable in PEMFC anode gas specification. Permeation mechanism through the membrane was mainly molecular sieving.