• Microbiology and Biotechnology Letters
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• v.15 no.2
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• pp.129-134
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• 1987

Aspergillus sp. (MK-24) producing a biological active substance that inhibited the venom proteinase activity was isolated from soil. The substance also inhibited the activity of trypsin and coagulation of blood, but did not inhibit papain, $\alpha$-chymotrypsin and pepsin. The substance was partially purified from culture filtrate by precipitaion with acetone, and by chromatography of DEAE-Sepadex A-50 column and Amberlite IRC-50 ion exchange. The inhibitory substance was stable in the wide pH range from 2.0 to 12.0 at 37$^{\circ}C$, but not stable at $65^{\circ}C$ in the alkaline pH. Only 12% of the activity was decreased by the heat treatment at 10$0^{\circ}C$ for two hours. The inhibition on venom proteinase (Agkistrodon bromohoffi brevicaudus) was a mixed type. The inhibitory activity depended on the preincubation time and completely depressed by cupric, zinc and cobalt ions. The inhibition on the venom proteinase was appeared strongly on casein but not on ovalbumin or hemoglobin as a substrate.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.5
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• pp.527-534
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• 2006

The purpose of this study is the development of more effective filter-type polymer adsorbent for removal of anionic pollutants from wastewater. In order to synthesize the polymer adsorbent that possesses anionic exchangeable function, carboxyl(-COOH) group of PP-g-AA nonwoven fabric was converted into amine($-NH_2$) group by the chemical modification using diethylene triamine(DETA). FT-IR data indicate that amine group was introduced into PP-g-AA through amidation of grafted acrylic acid by reaction with DETA. The degree of amination increased with increase in the reaction time and temperature of the chemical modification process, and was significantly improved by the pre-swelling treatment of PP-g-AA with solvent and addition of metal chlorides as a catalyst in following order as $NH_4OH>MeOH{\geq}HCl{\geq}H_2O\;and\;AlCl_3>FeCl_3{\geq}SnCl_2{\gg}ZnCl_2{\geq}FeCl_2$, respectively. However, the addition of catalyst limited the reusability of DETA, hence was less useful from the viewpoint of cost effectiveness and waste management. The anion exchange capacity of the aminated PP-g-AA(PP-g-AA-Am) increased with increase in the degree of amination, but it reached maximum value at the degree of amination as about $50{\sim}60%$. The anion exchange capacity of PP-g-AA-Am was higher than those of commercial anion resins.

• Journal of the Korean Chemical Society
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• v.29 no.1
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• pp.52-60
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• 1985

Oxides of nitrogen (NO$_x$) in exhaust gases was determined by absorbing the gas in alkaline peroxide solution containing 0.03${\%}$ H2O2 and 0.1N NaOH. About 100 ppm of NO$_x$ was rapidly oxidized to NO$_2$ or N$_2$O$_5$ by H$_2$O$_2$ and required a contact time of 2 minutes with the absorbing solution for complete absorption. With vigorous shaking including air or oxygen gas, high concentration of NO$_x$ (>200 ppm) can be absorbed within 30 minutes. The remaining H$_2$O$_2$ affect the absorbance of color solution strongly. However, the excess H$_2$O$_2$ was completely decomposed by zinc powder 0.5g and the sample solution should be adjusted to the pH range 6.1∼6.6 before the reduction so that conversion of nitrate to nitrite ion is possible. The absorbed NO$_x$ is determined colorimetrically by the diazotization-coupling method with sulfonilamide and NEDA as the coupling agent. The sensitivity of the new method was 4.48 ${\times}$ 10$^4$ as molar absorptivity which was high sensitive compared with that obtained for the usual zinc reduction NEDA method with O$_3$. This method was far more rapid, brief and accurate than previously published O$_3$-NEDA method in Korean industrial standard.

• Korean Journal of Agricultural Science
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• v.38 no.4
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• pp.631-639
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• 2011

This research was conducted to investigate potential use of New Zealand spinach (Tetragonia tetragonoides) as a new vegetable crop which will be cultivating in salt-affected soils including reclaimed land. Traditionally New Zealand spinach has been studied to explore functional compound or salt removing potential. To cultivate the crop species in the salt-affected soil widely, it is essential to obtain salt and soil texture responses under the controlled environment. Fifty nine New Zealand spinach ecotypes native to Korean peninsula first collected over seashore areas, and primitive habitat soil environment was evaluated by analyzing soil chemical properties from 32 locations. Different textures of sandy, silt loam, and sandy loam soils were prepared from nearby sources of sea shore, upland and paddy soils, respectively. Target salinity levels of 16.0 dS/m, 27.5 dS/m, 39.9 dS/m, and 52.4 dS/m in electrical conductivity (ECw) were achieved by diluting of 25, 50, 75, 100% (v/v) sea water to tap water (control, 0.6 dS/m), respectively. Various measurements responding to soil texture and irrigation salinity included plant height, root length, fresh weight (FW), dry weight (DW), leaf parameters (leaf number, leaf length, leaf width), lateral branching, and inorganic ion content. was found to adapt to diverse habitats ranging various soil chemical properties including soil pH, organic matter, exchangeable bases, EC, and cation exchange capacity (CEC) in Korea. Responding to soil texture, New Zealand spinach grew better in silt loam and sandy loam soil than in sandy soil. Higher yield (FW and DW) seemed to be associated with branch number (r=0.99 and 0.99, respectively), followed by plant height (r=0.94 and 0.97, respectively) and leaf number (r=0.89 and 0.84, respectively). Plant height, FW, and DW of the New Zealand spinach accessions were decreased with increasing irrigation salinity, while root length was not significantly different compared to control. Based on previous report, more narrow spectrum of salinity range (up to 16 dS/m) needs to be further studied in order to obtain more accurate salinity responses of the plant. As expected, leaf Na content was increased significantly with increasing salinity, while K and Ca contents decreased. Growth responses to soil texture and irrigation salinity implied the potential use of New Zealand spinach as a leafy vegetable in salt-affected soil constructed with silt loam or sandy loam soils.

• Clean Technology
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• v.14 no.3
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• pp.171-175
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• 2008

The effect of the addition of $Al^{3+}$ dopant on the electrochemical characteristics of $Li_{4}Ti_{5}O_{12}$ was investigated. $Li_{4}Ti_{5}O_{12}$ is known as a 2ero-strain material, and $Li_{3.95}Al_{0.15}Ti_{4.9}O_{12}$ has been manufactured by solid-state reaction with high energy ball milling (HEBM). The samples were heated at 800, 900 and $1000^{\circ}C$ in electric furnace. The structural and surface structures were measured by XRD (X-ray diffraction) and SEM (scanning electron microscopy). Cut-off voltage of charge/discharge cycles was $1.0{\sim}3.0 V$ to investigate reversible capacity, cycle stability and plateau voltage. The reversible capacity of $Li_{3.95}Al_{0.15}Ti_{4.9}O_{12}$ was 138 mAh/g.

• Korean Journal of Food Science and Technology
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• v.16 no.2
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• pp.235-241
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• 1984

Two fractions of pectinesterase from Chinese cabbage were isolated by ammonium sulfate fractionation, ion exchange chromatography on DEAE-cellulose and Sephadex G-150 gel filtration. The fraction F-A and F-B were purified approximately 340- and 10-fold. The similar salt effects and pH optima (pH 7.5-8.0) were obtained for the two pectinesterase fractions. The maximum activity of both two. fractions were obtained at 20-50mM of divalent rations and at 250mM of monovalent rations. The apparent Michaelis constant of the F-A was 0.01% for citrus pectin. The temperature optima for F-A and F-B were $48^{\circ}$ and $55^{\circ}C$, respectively and both fractions were stable in the region of pH 5.0-8.0 at room temperature. The thermal inactivation of the two fractions followed the first order reaction kinetics. From D and Z-values obtained the thermal resistance of the two fractions were characterized.

• Journal of Environmental Science International
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• v.27 no.7
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• pp.597-610
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• 2018

This study observed particulate matter ($PM_{2.5}$ and $PM_{10}$) in the downtown area of Jeju City, South Korea, to understand the chemical composition of particulates based on an analysis of the water-soluble ionic species contained in the particles. The mass fraction of the ionic species in the sampled $PM_{10}$ and $PM_{2.5}$ was 44.3% and 42.2%, respectively. In contrast, in Daegu City and Suwon City, the mass fraction of the ionic species in $PM_{2.5}$ was higher than that in $PM_{10}$. The chloride depletion percentage of $PM_{10}$ and $PM_{2.5}$ in Jeju City was higher than 61% and 66%, respectively. The contribution of sea-salt to the mass of $PM_{10}$ (5.9%) and $PM_{2.5}$ (2.6%) in Jeju City was similar to that in several coastal regions of South Korea. The mass ratio of $Cl^-$ to $Na^+$ in the downtown area of Jeju City was comparable to that in some coastal regions, such as the Gosan Area of Jeju Island, Deokjeok Island, and Taean City. The mass fraction of sea-salt in $PM_{10}$ and $PM_{2.5}$ was very low, and the concentration of sodium and chloride ions in $PM_{10}$ was not correlated with those in $PM_{2.5}$ ($R^2$ < 0.2), suggesting that the effects of sea-salt on the formation of particulate matter in Jeju City might be insignificant. The relationship between $NH_4{^+}$ and several anions such as $SO_4{^{2-}}$, $NO_3{^-}$, and $Cl^-$, as well as the relationship between the measurement and calculation of ammonium ion concentration, suggested that sea-salts may not react with $H_2SO_4$, and $(NH_4)_2SO_4$ may be a major secondary inorganic aerosol component of $PM_{2.5}$ and $PM_{10}$ in Jeju City.

• Journal of the Korean Electrochemical Society
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• v.14 no.1
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• pp.27-32
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• 2011

The electorchemical properties of $Li_4Ti_5O_{12}$ added with Cr was tested. The addition or substitution of atoms to $Li_4Ti_5O_{12}$ are expected to modify the crystal structure, and therefore to change the electrochemical performances of $Li_4Ti_5O_{12}$. After the spinel structure $Li_4Ti_{5-x}Cr_xO_{12}$ (x = 0~0.2) were obtained via sol-gel method, the gel was heated in a muffle furnace at $800{\sim}850^{\circ}C$ for 12 h in air. The physical properties of the samples were characterized by TG-DTA, XRD, SEM, FT-IR, and the electrochemical properties were tested with battery cycler at 0.01~2.0 V range. The $Li_4Ti_5O_{12}$ exhibited 169.9 mAh/g at 1C and capacity recovery was 97.5% of the initial capacity at 0.1C. $Li_4Ti_{4.9}Cr_{0.1}O_{12}$ (Cr 1% added) showed best performance of 193.8 mAh/g at 1C and the capacity recovery was increased to 98.8% of the initial capacity at 0.1C.

• Polymer(Korea)
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• v.35 no.4
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• pp.363-369
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• 2011

To study the effect of incorporation of a surface crosslinking layer on a crosslinked poly (sodium acrylate) (cPSA) absorbent with ethylene glycol dimethacrylate CEGDMA), we synthesized several surface crosslinked cPSAs with EGDMA by an inverse emulsion polymerization method to delay the absorption of excess water in concrete, Liquid paraffin was used as a continuous phase. cPSA was synthesized with acrylic acid (AA) neutralized with aqueous 8 M sodium hydroxide solution as a monomer, N,N-methylene bisacrylamide (MBA) as crosslinking agent and ammonium persulfate (APS) and sodium metabisulfite (SMBS) as a redox initiator system by inverse emulsion polymerization. FTIR spectroscopy was used to characterize $Ca^{2+}$ ion interaction with cPSA and cPSA-EGDMAs. The swelling ratios of synthesized absorbents were evaluated from the absorption in deionized water, cement saturated aqueous solution and aqueous solution of calcium hydroxide (pH 12). Equilibrium swelling times for cPSA and surface crosslinked cPSA with EGDMA were 2 and 3 hrs, respectively. We also observed an increase in setting time of the cement and an increase in the compressive strength of mortar by addition of the synthesized cPSA-EGDMA.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.220-220
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• 2013

Surface-normal transmission electro-absorption modulator (EAM) are attractive for high-definition (HD) three-dimensional (3D) imaging application due to its features such as small system volume and simple epitaxial structure [1,2]. However, EAM in order to be used for HD 3D imaging system requires uniform modulation performance over large area. To achieve highly uniform modulation performance of EAM at the operating wavelength of 850 nm, it is extremely important to remove the GaAs substrate over large area since GaAs material has high absorption coefficient below 870 nm which corresponds to band-edge energy of GaAs (1.424 eV). In this study, we propose and experimentally demonstrate a transmission EAM in which highly selective backside etching methods which include lapping, dry etching and wet etching is carried out to remove the GaAs substrate for achieving highly uniform modulation performance. First, lapping process on GaAs substrate was carried out for different lapping speeds (5 rpm, 7 rpm, 10 rpm) and the thickness was measured over different areas of surface. For a lapping speed of 5 rpm, a highly uniform surface over a large area ($2{\times}1\;mm^2$) was obtained. Second, optimization of inductive coupled plasma-reactive ion etching (ICP-RIE) was carried out to achieve anisotropy and high etch rate. The dry etching carried out using a gas mixture of SiCl4 and Ar, each having a flow rate of 10 sccm and 40 sccm, respectively with an RF power of 50 W, ICP power of 400 W and chamber pressure of 2 mTorr was the optimum etching condition. Last, the rest of GaAs substrate was successfully removed by highly selective backside wet etching with pH adjusted solution of citric acid and hydrogen peroxide. Citric acid/hydrogen peroxide etching solution having a volume ratio of 5:1 was the best etching condition which provides not only high selectivity of 235:1 between GaAs and AlAs but also good etching profile [3]. The fabricated transmission EAM array have an amplitude modulation of more than 50% at the bias voltage of -9 V and maintains high uniformity of >90% over large area ($2{\times}1\;mm^2$). These results show that the fabricated transmission EAM with substrate removed is an excellent candidate to be used as an optical shutter for HD 3D imaging application.