• Journal of Korean Society of Environmental Engineers
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• v.35 no.4
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• pp.283-288
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• 2013

To evaluate the ability of the submerged plant, Ceratophyllum demersum's (C. demersum) to remove nutrients and to inhibit growth of cyanobacteria, a total of 6 mesocosms were conducted in a batch reactor for 9 days. From the 84 hr of the experiment, C. demersum was stabilized and showed daily cycle trends according to changes in pH and DO levels. The concentration of nutrients, $NH_3{^+}$, $NO_3{^-}$ and $PO_4{^3}$ continuously decreased until 9 days of the experiment, with the rapid decrease in nutrient concentration for the first 24 hours. High correlation coefficient ($r^2{\geq}0.96$, p<0.001) between the amount of C. demersum's biomass per unit area and the nutrients removal level were derived, and greater C. demersum's biomass per unit area showed higher removal efficiency of nutrients. However, there were differences in the C. demersum's activity level between batch reactors with higher and similar density of the C. demersum, but nonetheless water purification effect appears to have a significant influence due to attached algae and microorganisms. The growth rate of harmful cyanobacteria, Microcystis aeruginosa (M. aeruginosa) with C. demersum's density of 2,500 g $fw/m^2$ (100% of cover degree) was 0.31 /day, compared to the growth rate of 0.47 /day for the control group (0% of cover degree). In terms of number of cells, the control group had 1.7 times higher number of cells than the experimental group, proving that C. demersum has the ability to inhibit the growth of harmful cyanobacteria.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.85-92
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• 2005

The performance of a novel fermentation process, adopting a sludge blanket type configuration for higher hydrolysis/acidogenesis of the municipal primary sludge, was investigated under batch and semi-continuous conditions with various pH and temperature conditions. This acid elutriation slurry reactor provided higher system performance with a short HRT (5 days) and higher acidogenic effluent quality under pH 9 and thermophilic ($55^{\circ}C$) conditions. The hydrolysis of the sludge was revealed to be significantly dependent on seasonal effects for sludge characteristics but with little impact on acidogenesis. Based on the rainy season at the optimum conditions, VFA production and recovery fraction ($VFA_{COD}/COD$) were $0.18\;g\;VFA_{COD}\;g^{-1}\;VSS_{COD}$ and 63%. As byproducts, nitrogen and phosphorus releasing were $0.006\;g\;N\;g^{-1}\;VSS_{COD}$ and $0.003\;g\;P\;g^{-1}\;VSS_{COD}$, respectively. For the mass balance in a full-scale plant($Q=158,880\;m^3\;day^{-1}$) based on the rainy season, the VFA and non-VFA(as COD) production were $3,110\;kg\;VFA_{COD}\;day^{-1}$ and $1,800\;kg\;COD\;day^{-1}$, resulting in an increase of organics of $31\;mg\;COD\;L^{-1}$ and $20\;mg\;VFA_{COD}\;L^{-1}$ and nutrients of $0.7\;mg\;N\;L^{-1}$ and $0.3\;mg\;P\;L^{-1}$ in the influent sewage. The economical benefit from this process application was estimated to be about $67 per $1,000m^3$ of sewage except for energy requirements and also, better benefits can be expected during the dry season. Also, the results revealed that the process has various additional advantages such as pathogen-free stabilized solids production, excellent solids control and economical benefits.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.9
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• pp.1328-1334
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• 2010

Low-trans spread fat (LTSF) was produced by lipase-catalyzed synthesis of canola (CO) and fully hydrogenated soybean oil (FHSBO) at 65:35 (w/w). Blend of CO and FHSBO with 65:35 ratio was interesterified using Lipozyme TLIM (immobilized Thermomyces lanuginosus, 20% of total substrate) in a 1 L-batch type reactor at $70^{\circ}C$ with 500 rpm for 24 hr. Then, physicochemical melting properties of LTSF were compared with commercial spread fat. At $20^{\circ}C$, solid fat contents (SFC) of commercial spread fat as a control and LTSF were similar, showing 19.1 and 18.1%, respectively. Major compositional fatty acids of LTSF were C18:0, C18:1 and C18:2 (29.2, 41.8 and 13.3 wt%, respectively). Trans fatty acid content of the LTSF (0.2 wt%) was lower than that of commercial spread fat (5.5 wt%). In the RP-HPLC analysis from LTSF, major triacylglycerol (TAG) molecules were SOL (stearoyl-oleoyl-linoleyl), SOO, POS/PSP, and SOS. Also, polymorphic form and x-ray diffraction of LTSF showed coexistence of $\beta$' and $\beta$ form crystals.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.83-86
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• 2010

Purpose: The Molybdenum which is the raw material of $^{99}Mo$-$^{99m}Tc$ generator (generator) is produced from the nuclear reactor. However, output has dwindled as the two nuclear reactors supplying the bulk of radioactive material-one in Chalk River, Ontario and the other in Petten, the Netherlands-have been closed for repairs or maintenance. This resulted in the enhancement of its price. Therefore we have tried to seek the new method which could run generator to increase activity of $^{99m}Tc$ in this study. Materials and Methods: The $^{99m}Tc$ activity obtained from 5 times elution for 5 days from Monday to Friday using two generators was compared with 10 times elution. Appearance test, pH test, LAL test, sterility test, chemical impurity(Al) test, radio chemical purity test, ratio of $^{99}Mo$/$^{99m}Tc$ activity test have been done to check the stability of $^{99m}Tc$ eluting from generator respectively. Results: The $^{99m}Tc$ activity obtained from 5 times elution for 5 days was 168.2 GBq (4545 mCi) and 10 times was 230.5 GBq (6230 mCi). All quality control tests were within normal limit. Conclusion: We got to know that 2 times elution a day obtained more $^{99m}Tc$ activity than one time elution in this study.

• Journal of Animal Environmental Science
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• v.13 no.1
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• pp.13-20
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• 2007

Sawdust biofiltration is an emerging bio-technology for control of ammonia emissions including compost odors from composting of biological wastes. Although sawdust is widely used as a medium for bulking agent in composting system and for microbial attachment in biofiltration systems, the performance of agitated bed composting and sawdust biofiltration are not well established. A pilot-scale composting of hog manure amended with sawdust and sawdust biofiltration systems for practical operation were investigated using aerated and agitated rectangular reactor with compost turner and sawdust biofilter operated under controlled conditions, each with a working capacity of approximately $40m^3\;and\;4.5m^3$ respectively. These were used to investigate the effect of compost temperature, seed germination rate and the C/N ratio of the compost on ammonia emissions, compost maturity and sawdust biofiltration performance. Temperature profiles showed that the material in three runs had been reached to temperature of 55 to $65^{\circ}C$ and above. The ammonia concentration in the exhaust gas of the sawdust biofilter media was below the maximum average value as 45 ppm. Seed germination rate levels of final compost was maintained from 70 to 93% and EC values of the finished compost varied between 2.8 and 4.8 ds/m, providing adequate conditions for plant growth.

• Clean Technology
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• v.24 no.2
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• pp.127-134
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• 2018

To reduce the environmental pollution by $NO_x$ from ship engine, International maritime organization (IMO) announced Tier III regulation, which is the emmision regulation of ship's exhaust gas in Emission control area (ECA). Selective catalytic reduction (SCR) process is the most commercial $De-NO_x$ system in order to meet the requirement of Tier III regulation. In generally, commercial ceramic honeycomb SCR catalyst has been installed in SCR reactor inside marine vessel engine. However, the ceramic honeycomb SCR catalyst has some serious issues such as low strength and easy destroution at high velocity of exhaust gas from the marine engine. For these reasons, we design to metallic structured catalyst in order to compensate the defects of the ceramic honeycomb catalyst for applying marine SCR system. Especially, metallic structured catalyst has many advantages such as robustness, compactness, lightness, and high thermal conductivity etc. In this study, in order to support catalyst on metal substrate, coating slurry is prepared by changing binder. we successfully fabricate the metallic structured catalyst with strong adhesion by coating, drying, and calcination process. And we carry out the SCR performance and durability such as sonication and dropping test for the prepared samples. The MFC01 shows above 95% of $NO_x$ conversion and much more robust and more stable compared to the commercial honeycomb catalyst. Based on the evaluation of characterization and performance test, we confirm that the proposed metallic structured catalyst in this study has high efficient and durability. Therefore, we suggest that the metallic structured catalyst may be a good alternative as a new type of SCR catalyst for marine SCR system.

• Clean Technology
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• v.22 no.2
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• pp.132-138
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• 2016

The emission of SO₂ is inevitable in case of combustion of most fossil fuels except LNG in commercial power plant which has a bad effect on the durability of SCR catalyst. To develop a low temperature SCR catalyst which has a high NOx removal performance and excellent durability to SO₂, V₂O₅/TiO₂ catalysts were prepared by coating on the metal foam substrate with the impregnation amount of Sb₂O₃ as promotor. This study has evaluated the NOx removal performance and the durability to SO₂ on a laboratory scale atmospheric reactor and analyzed the properties of the prepared catalysts by means of porosimeter, BET, SEM (scanning electron microscope), EDX (energy dispersive x-ray spectrometer), XPS (X-ray photoelectron spectroscopy). It was found that the surface area of catalyst increased with the impregnation amount of Sb₂O₃ and the NOx removal performance showed the highest value at the 2 wt% impregnation of Sb₂O₃. This results was considered to be due to the optimum active site on the catalyst surface. And also, Sb₂O₃ impregnated catalysts presented that NOx removal performance was maintained despite the exposure to SO₂ for 5 hours. Therefore it was confirmed that metal foam SCR catalyst for low temperature could be manufactured with the optimum control of Sb₂O₃ impregnation according to the SO₂ presence or not.

• Resources Recycling
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• v.32 no.1
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• pp.50-59
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• 2023

The amount of dust generated during the dissolution of scrap in an electric arc furnace is approximately 1.5% of the scrap metal input, and it is primarily collected in a bag filter. Electric arc furnace dust primarily consists of zinc and ion. The processing of zinc starts with its conversion into pellet form by the addition of a carbon-based reducing agent(coke, anthracite) and limestone (C/S control). These pellets then undergo reduction, volatilization, and re-oxidation in rotary kiln or RHF reactor to recover crude zinc oxide (60%w/w). Next, iron is discharged from the electric arc furnace dust as a solid called Fe clinker (secondary by-product of the Fe-base). Several methods are then used to treat the Fe clinker, which vary depending on the country, including landfilling and recycling (e.g., subbase course material, aggregate for concrete, Fe-source for cement manufacturing). However, landfilling has several drawbacks, including environmental pollution due to leaching, high landfill costs, and wastage of iron resources. To improve Fe recovery in the clinker, we pulverized it into optimal -sized particles and employed specific gravity and magnetic force selection methods to isolate this metal. A carbon-based reducing agent and a binding material were added to the separated coarse powder (>10㎛) to prepare briquette clinker. A small amount (1-3%w/w) of the briquette clinker was charged with the scrap in an electric arc furnace to evaluate its feasibility as an additives (carbonaceous material, heat-generating material, and Fe source).