• Polymer(Korea)
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• v.32 no.5
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• pp.403-408
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• 2008

Keratin is the major structural fibrous protein providing outer covering such as wool, hair, and nail. Keratin is useful as natural protein. We developed the keratin loaded poly(L-lactide-co-glycolide) (PLGA) scaffolds (keratin/PLGA) for the possibility of the application of the tissue engineering using bone marrow mesenchymal (BMSCs). Keratin/PLGA (contents 0%, 10%, 20% and 50% of PLGA weight) scaffolds were prepared by solvent casting/salt leaching method. We characterized porosity, wettability, and water uptake ability, DSC of keratin/PLGA scaffold. We seeded BMSCs isolated from the femurs of rat into the inner core of the hybrid scaffold. Celluar viability were assayed by 3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyl-tetrazolium bromide (MTT) test. We confirmed that keratin/PLGA scaffold is hydrophilic by wettability, and water uptake ability measurement results. In MTT assay results, cell viability in scaffolds impregnated 10 and 20 wt% of keratin were higher than other scaffolds. In conclusion, we suggest that keratin/PLGA scaffold may be useful to tissue engineering using BMSCs.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2263-2273
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• 2000

Catalytic wet air oxidation of acetic acid over Mn-Ce based catalysts deposited on various supports ($SiO_2$, $TiO_2$, $ZrO_2$), $ZrSiO_4$, $ZrO_2(10wt%)/TiO_2$) have been carried out in high pressure microreactors. Also, promotional effects by small addition(O.5~1.0 wt%) of p-type semiconductors (CoO, $Ag_2O$, SnO) have been investigated. From the screening tests for initial activity ranking, both Mn(2.8)-Ce(7.2 wt%) and Ru(O.4)Mn(2.7)-Ce(6.9 wt%) supported on $TiO_2$ were selected as the promising reference candidates. In $Mn-Ce/TiO_2$ reference catalyst, addition of small amount of each p-type semiconductor (Co, Sn and Ag) resulted in activity promotional effect and the degree of the increase was in the following order: Co> Ag > Sn. Especially, $Mn-Ce/TiO_2$ promoted with 0.5 wt% Co gave the 2.6 folds activity increase compared to the reference case attributing to the surface area increase as well as synergy effect. In $Ru-Mn-Ce/TiO_2$ reference catalyst, only Co(1.0 wt%) promoted case showed a little reaction rate increase.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.253-259
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• 2012

Disposal of high amount of coal combustion by-products, such as fly ash and bottom ash, is of a great concern to the country, due to the huge treatment cost and land requirement. On the other hand, those coal-ash wastes are considered to have desirable characteristics that may improve physical, chemical, and biological properties of soils. Especially, compared with fly ash, bottom ash has a larger particle size, porous surface area, and usable amount of micronutrients. In the present study, we examined bottom as a soil amendment for mitigating $CO_2$ emission and enhancing carbon sequestration in soils fertilized with organic matter (hairy vetch, green barely, and oil cake fertilizer). Through laboratory incubation, $CO_2$ released from the soil was quantitatively and periodically monitored with an enforced-aeration and high-temperature respirometer. We observed that amendment of bottom ash led to a marked reduction in $CO_2$ emission rate and cumulative amount of $CO_2$ released, which was generally proportional to the amount of bottom ash applied. We also found that the temporal patterns of $CO_2$ emission and C sequestration effects were partially dependent on the relative of proportion labile carbon and C/N ratio of the organic matter. Our results strongly suggest that amendment of bottom ash has potential benefits for fixing labile carbon as more stable soil organic matter, unless the bottom ash contains toxic levels of heavy metals or other contaminants.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.776-780
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• 2007

A biofilm reactor packed with porous media was investigated for nitrogen removal of synthetic wastewater. The effect of different loading rates on the nitrification was sustained to be steady state with stable efficiency of 50~60% in the range of $0.0083{\sim}0.017gNH_4-N/gMLVSS{\cdot}day$ of F/MN ratio and $1{\sim}2kgNH_4-N/m^3{\cdot}day$ of media volumetric loading rate. However, nitrification efficiency was rapidly decreased to 25~30% as F/MN ratio and media volumetric loading rate were increased to the range of $0.025{\sim}0.034gNH_4-N/gMLVSS{\cdot}day$ and $3{\sim}4kgNH_4-N/m^3{\cdot}day$, respectively. Also the consumption rate of alkalinity was higher under 8 hours of HRT than unter 6 hours of HRT. Accordingly the influent loading rate variation by detention time with influent flow influenced more on the nitrification efficiency than the influent loading rate variation by the influent concentration did. The temperature effect on the nitrification showed 25% higher in summer than in winter as the results reported by other researchers who reported that the nitrification efficiency in biofilm showed 20% increase from 55% to 75% when the temperature was raised from $20^{\circ}C$ to $25^{\circ}C$. Denitrification with sulfur-media showed 90% removal efficiency under steady-state with no effect from the increase of influent concentration and empty bed contact time (EBCT) change such as EBCT was decreased from 8.4 hr to 4.3 hr and $NO_3-N$ loading rate was changed within the range of $0.1{\sim}0.4kgNO^3-N/m^3{\cdot}day$. Accordingly Denitrification with sulfur-media is feasible for post denitrification at the concentration less than $80mgNO^3-N/L$.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.1092-1099
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• 2022

Research on exhaust aftertreatment devices to reduce air pollutants and greenhouse gas emissions is being actively conducted. However, in the case of the particulate matters/nitrogen oxides (PM/NOx) simultaneous reduction device for ships, the problem of back pressure on the diesel engine and replacement of the filter carrier is occurring. In this study, for the optimal design of the integrated device that can simultaneously reduce PM/NOx, an appropriate standard was presented by studying the flow inside the device and change in back pressure through the inlet/outlet pressure. Ansys Fluent was used to apply porous media conditions to a diesel particulate filter (DPF) and selective catalytic reduction (SCR) by setting porosity to 30%, 40%, 50%, 60%, and 70%. In addition, the ef ect on back pressure was analyzed by applying the inlet velocity according to the engine load to 7.4 m/s, 10.3 m/s, 13.1 m/s, and 26.2 m/s as boundary conditions. As a result of a computational fluid dynamics analysis, the rate of change for back pressure by changing the inlet velocity was greater than when inlet temperature was changed, and the maximum rate of change was 27.4 mbar. This was evaluated as a suitable device for ships of 1800kW because the back pressure in all boundary conditions did not exceed the classification standard of 68mbar.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3B
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• pp.303-310
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• 2009

Natural zeolite is widely used as sorbents and bio-media materials because it is cheap as well as it has efficient porous structures and large cation exchange. In this study, the effect of metal cations $(Na^+,\;Ca^{2+},\;Mg^{2+},\;Al^{3+})$ adsorbed to natural zeolite on the microorganism attachment was investigated. Metal-modified zeolites (MMZ) were prepared with 0.01 M, 0.02 M and 0.1 M NaCl, $CaCl_2$, $MgCl_2$ and $AlCl_3$ solutions respectively, which concentrations were equivalent to 10%, 20% and 100% of cation exchange capacity (CEC) of natural zeolite. Pseudomonas putida was used as microorganism which was cultivated in Beef Extract Medium at $26^{\circ}C$. The microorganism attachment to MMZ was increased more than natural zeolite. The amount of bacterial adhesion to MMZ and natural zeolite were $Mg^{2+}>natural>Na^+>Al^{3+}>Ca^{2+}$ under 10% of CEC, $Mg^{2+}>Ca^{2+}>Al^{3+}>natural>Na^+$ under 20% of CEC and $Ca^{2+}>Mg^{2+}>natural>Al^{3+}>Na^+$ under 100% of CEC. Especially, Mg-modified zeolite (Mg-MZ) showed the highest amount of bacterial adhesion, which increased the microorganism attachment 60% higher than natural zeolite under 10% of CEC. However, the amount of bacterial adhesion was decreased as the concentration of metal cations modified to zeolite were increased, showing that the increased amounts were 60% under 10% of CEC, 50% under 20% of CEC and 10% under 100% of CEC in Mg-MZ. Additionally, the effect of $Mg^{2+}$ in solution on the bacterial adhesion was investigated in order to compare it with the effect of $Mg^{2+}$ adsorbed to zeolite. The maximum quantity of bacterial adhesion to Mg-MZ was not different from the amount of microorganism attachment to the natural zeolite when $Mg^{2+}$ solution was added.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.1
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• pp.5-9
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• 2008

Cordierite has a very low thermal expansion coefficient, but has problem that it has a weak mechanical strength and is apt to be attacked by acid such as sulfur for using as a diesel particulate filter support. The physical properties of $ZrTiO_4$ modified with $SiO_2,\;Al_2O_3$, MoOx, $Cr_2O_3\;and\;Nb_2O_5$ were investigated with XRD, SEM, UTM and thermal expansion, etc. in this paper. $ZrTiO_4$ powder was synthesized as a monoclinic structure with processes that starting materials of $TiO_2\;and\;ZrO_2$ were mixed with ball mill and calcined above $1240^{\circ}C$ for 3 hr. Additive modified $ZrTiO_4$ specimens for flexural strength and thermal expansion measurement were obtained by mixing $ZrTiO_4$ powder with additives, pressing and firing at $1300^{\circ}C$ for 3 hr. The porosity of additive modified $ZrTiO_4$ decreased monotonically with increasing additive content by 5 wt% regardless of additive types and saturated for further increase of additive by 10wt. The flexural strength of $Al_2O_3$ (5, 10 wt%) modified $ZrTiO_4$ shows a large increase, but that of other additives modified $ZrTiO_4$ decreased. The thermal expansion coefficient of additive modified $ZrTiO_4$ except $Nb_2O_5$ decreased continuously with the content of additive. In particular, the lowest thermal expansion coefficient of $ZrTiO_4$ was obtained for the additive of $SiO_2$.