• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.840-845
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• 2011

Degradation products of agarose are biologically active and thus used as an ingredient in pharmaceuticals or functional cosmetics. Furthermore, it has been strongly considered as a substrate for bio-ethanol fermentation. Recently, we isolated new agarase-producing microorganism, Pseudoalteromonas sp. from south sea of Korea. In this study, we aimed to separate and purify the agarase from culture broth of this strain. Separation of agarase was performed by ion- exchange chromatography on DEAE-Sepharose resin. Equilibrium pH and volume ratio of resin to the amount of protein were optimized for the efficient adsorption of protein. 410 ${\mu}g$ of protein was completely adsorbed to 3 mL of resin at pH 7.5. The total amount of eluted protein increased as NaCl concentration increased to 400 mM at isocratic elution. Agarase was separated by linear gradient elution of NaCl (0~1,000 mM). Three major protein peaks were observed and the presence or absence of agarase in these eluted proteins was measured by Lugol's staining technique. Only six eluted protein fractions showed strong agarase activity.

• KSBB Journal
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• v.22 no.2
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• pp.102-108
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• 2007

A sewage was treated using a vertical flow zeolite-filled reed bed. The sewage from the student dormitory of Changwon National University was fed into the reed bed for 10 minutes every 6 hours at the hydraulic load of $314L/m^3{\cdot}$day. The filtering height of the reed bed was 100 em and the zeolite mixture was filled in the reed bed. The mixture consisted of the same volume of two types of zeolite: 0.5$\sim$1 mm and 1$\sim$3 mm in diameter. Annual average removal efficiency was 88 89.9%, $COD_{Cr}$ 86.1 %, $COD_{Mn}$ 81.2%, T-N 34.0%, $NH_4^+$-N 97.3% and T-P 34.6%. T-N of effluent was mostly $NO_3^-$-N and the concentration of $NO_2^-$-N in effluent was lower than 0.1 mg/L. All removal efficiencies did not show a remarkable seasonal change. The ranking of phosphorous fractions fixed to the zeolite in column test was Ca-P > Fe-P > reductant soluble Fe-P > occluded P > saloid P > AI-P at all depths of the filter. All phosphorous fractions except for AI-P reduced at deeper filter layer, while their content ratios increased at deeper filter layer. Organic matter content was the highest at the highest layer (0$\sim$5 cm from the top of the filter) and only small differences were observed at the deeper filter layer than 5 em from the top. Organic matter content increased at all depths of the filter with the operating time.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.7
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• pp.515-520
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• 2009

This study investigated the influence of oxyanions (nitrate, carbonate, phosphate) on the attachment of bacteria (Bacillus subtilis) to Al-Fe bimetallic oxide-coated sand using column experiments. Results showed that bacterial attachment to the coated sand was independent of nitrate concentration. Bacterial mass recovery remained constant (10.9${\pm}$0.2%) with varying nitrate concentrations (0.1, 1, 10 mM). In case of carbonate, mass recovery increased from 25.6% to 39.0% with increasing carbonate concentration from 0.1 mM to 1 mM, and mass recovery also increased from 50.9% to 78.9% at the same concentration condition in case of phosphate. This phenomenon could be attributed to the hindrance effect of carbonate and phosphate to bacterial attachment to the coated sand. Meanwhile, with increasing carbonate/phosphate concentration from 1 mM to 10 mM, mass recovery decreased from 39.0% to 23.8% and from 78.9% to 52.6%, respectively. This phenomenon could be ascribed to the enhancement effect of free carbonate/phosphate ions present in solution phase due to increasing carbonate/phosphate concentration, which increase ionic strength and thus enhance bacterial attachment to the coated sand. In our experimental conditions, the effect of phosphate to bacterial attachment to the coated sand was the greatest among phosphate, carbonate, and nitrate.

• Journal of Korean Society of Forest Science
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• v.90 no.1
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• pp.133-138
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• 2001

Increased base cation loss and Al mobilization, a consequence of soil acid neutralization responses, are common in air polluted areas showing forest decline. The prediction models of acid neutralization responses were developed by using indicators of soil acidification level(pH, and base saturation) in order to assess the forest soil sensitivity to acidification. The soil acidification level was greatest in Namsan followed by Kanghwa, Ulsan, and Hongcheon, being contrary to regional total $ANC_H$ pattern through soil columns leached with additional acid ($16.7mmol_c\;H^+/kg$), Both base exchange and Al dissolution were main acid neutralization processes in all study regions. There were low base exchange and high Al dissolution in the regions of the low total $ANC_H$. The $ANC_M$ by sulfate adsorption was greatest in Hongcheon compared with other regions even though the AN rate was very low as 6.4%. Coefficients of adjusted determination of simple and multiple regression models between soil acidification level indicators and the acid neutralization responses were more than 0.52(p<0.04) and 0.89(p<0.01), respectively. The result suggests that soil pH and base saturation are available indicators for predicting the acid neutralization responses. These prediction models could be used as an useful method to measure forest soil sensitivity to acidification.

• Nuclear Engineering and Technology
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• v.22 no.1
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• pp.20-28
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• 1990

In this study the migration experiment using packed column with crushed tuff was conducted as a basic research to develop migration model of radionuclides through geologic media. The main emphasis was put on evaluating the validity of migration models. For this, two models were introduced: one is the model which is based on the assumption of instantaneous equilibrium reaction and the other the model based on kinetic process such as intraparticle diffusion. The coefficient of hydrodynamic dispersion in packed column was determined using iodine as nonsorbing tracer. The hydrodynamic dispersion coefficient, D$_{L}$ was shown to be 0.11$\times$10$^{-2}$ $\textrm{cm}^2$/min under the condition of the column porosity of 0.483 and the average water velocity of 0.915$\times$10$^{-2}$ cm/min. The distribution coefficient, Kd of Cs-137 on crushed tuff was 11.3 cc/g at the concentration of 2$\times$10$^{-6}$ M and the temperature of 2$0^{\circ}C$. The breakthrough curve of Cs-137 through packed column was shown to have an asymmetric curve in which long trailing tail appears at the end part of the curve. The results obtained from the comparison of introduced models with experimental data indicated that the mass transfer model with intraparticle diffusion as rate-controlling step simulated the behaviors of Cs-137 migration more adequately, when compared with the bulk reaction model in which the assumption of instantaneous equilibrium reaction was maded. Consequently, the intraparticle diffusion was found to be an important factor in the migration of Cs-137 through packed column.n.

• Clean Technology
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• v.16 no.4
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• pp.258-264
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• 2010

This study estimated the possibility of phosphate removal characteristics to utilize EAF(electric arc furnace) slag as submarine cover material. The major phosphate removal mechanism was a certain formation of HAP precipitation occurred by the ionization reaction between $Ca^{2+}$ and $OH^-$, which were leached from the EAF Slag. Another phosphate removal mechanism was the adsortion of EAF slag surface. As a result of $PO_4{^-}-P$ removal characteristics using continuous column reactor, $PO_4{^-}-P$ concentration decreased rapidly after 3 days and 10 days later, it show under 0.5 ppm. The result as applied in real sea water, shows that the phosphate removal effects were 93~98% by the subaqueous sediment removal using the EAF slag. In conclusion, EAF slag is useful in $PO_4{^-}-P$ removal and control and it is possible to use without additional process like crush and selection.

• The Korean Journal of Pesticide Science
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• v.15 no.3
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• pp.254-268
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• 2011

Fenoxycarb, pyriproxyfen and methoprene are juvenile hormone mimic insecticide. These insecticides have been widely used for mosquito, fly, scale insects, and Lepidoptera. The purpose of this study was to develop a simultaneous determination procedure of fenoxycarb, pyriproxyfen and methoprene residues in crops using HPLC-UVD/MS. These insecticide residues were extracted with acetone from representative samples of four raw products which comprised brown rice, apple, green pepper, and Chinese cabbage. The extract was diluted with saline water, and then n-hexane/dichloromethane partition was followed to recover these insecticides from the aqueous phase. Florisil column chromatography was additionally employed for final clean up of the extract. The analytes were quantitated by HPLC-UVD/MS, using a $C_{18}$ column. The crops were fortified with each insecticide at 3 levels per crop. Mean recovery ratios were ranged from 80.0 to 104.3% in four representative agricultural commodities. The coefficients of variation were less than 4.8%. Quantitative limit of fenoxycarb, pyriproxyfen, and methoprene was 0.04 mg/kg in crop samples. A HPLC-UVD/MS with selected-ion monitoring was also provided to confirm the suspected residues. The proposed simultaneous analysis method was reproducible and sensitive enough to determine the residues of fenoxycarb, pyriproxyfen and methoprene in the agricultural commodities.