• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.479-484
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• 2011

The number of comstock mealybug, Pseudococcus comstocki (Kuwana) suddenly increased at ginseng fields in Yangpyeong, Gyeonggi-do from mid July to early August. By the late of September just before digging up the roots of ginseng, more than 8 individuals of the comstock mealybug per plant were occurred and evenly dispersed around the roots. Through the bioassay in the laboratory, six environmental friendly agricultural materials (for example, Nobug, Kkagsami, GB-1, GB-2, GB-3, GB-5) containing sophora extract or paraffin oil as main components were selected by the effective control agents for controlling the comstock mealybug. These selected agents showed a quite similar insecticidal activities to 2 insecticides such as clothianidin and thiamethoxam registered in control of ginseng insect pests. Also. in the ginseng field test, the agent containing sophora extract and paraffin oil, like 2 insecticides showed high control effects against the comstock mealybug.

• Microbiology and Biotechnology Letters
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• v.26 no.4
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• pp.316-322
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• 1998

An ${\alpha}$-D-galactosidase (${\alpha}$-D-galactoside galactohydrolase, EC 3. 2. 1. 22) from sunflower seed was purified by affinity chromatography using N-$\varepsilon$-aminocaproyl-${\alpha}$-D-galactopyranosylamine coupled to sepharose and its properties were examined. The specific activity of the purified enzyme, tested with p-nitrophenyl-${\alpha}$-D-galactopyranoside as substrate, was 291.66 units/mg protein, representing an 115-folds purification of the original crude extract. The final preparation obtained from by Sephadex G-25 chromatography showed a single band on SDS-polyacrylamide gel electrophoresis. The molecular weight was determined to be 42,000 by SDS-polyacrylamide gel electrophoresis. The purified galactosidase showed maximum activity at pH 4.5 and 55$^{\circ}C$, and was stable in the pH and temperature ranges of 4.0 to 5.0 and 30 to 55$^{\circ}C$, respectively. The enzyme activity was inhibited by Ag$\^$2+/, Hg$\^$2+/ and Co$\^$2+/. The enzyme activity was not affected considerably by treatment with other metal compounds. The enzyme liberated galactose from melibiose, raffinose, copra galactomannan, guar gum and locust bean gum by TLC, and also the hydrolysis rate of substrate was compared by HPLC.

• Journal of the Korean Electrochemical Society
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• v.9 no.2
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• pp.89-94
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• 2006

Nafion/poly(ether(amino sulfone)) acid-base blend polymer electrolyte membranes were prepared and their proton conductivity and dimethyl ether permeability were investigated. Characteristics of direct dimethyl ether fuel cell (DDMEFC) performance using prepared blend membrane were studied. The increase of amine groups in the base polymer in composite membranes resulted in the decrease in dimethyl ether permeability. The proton conductivity of the blend membranes gradually increased as increasing temperature. The conductivity of Nafion/PEAS-0.6 (85:15) blend membranes was measured to be $1.42\times10^{-2}S/cm\;at\;120^{\circ}C$ which was higher than that of the recast Nafion. The performance of direct dimethyl ether fuel cell (DDMEFC) using the Nafion/PEAS blend membranes was higher than that using $Nafion^(R)115$ membrane. Enhanced performance of direct dimethyl ether fuel cells using Nafion/PEAS blend membrane was explained by reducing dimethyl ether (DME) crossover through the electrolyte membrane and maintenance of the proton conductivity at high temperature.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.99-105
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• 2008

Core-shell structured $BaTiO_3$ powders were produced via nano-coating of $Cr_2O_3$ and $Mn_2O_3$ to barium titanate powder system for MLCCs. From preliminary experiments, the optimal solution reaction condition employing using $KMnO_4$, $K_2Cr_2O_4$ and sulfur was established. Not only powders of $Cr_2O_3$ and $Mn_2O_3$ were synthesized but also their coating on $BaTiO_3$ powders were peformed under the same reaction condition. The coating was carried out in two ways, one-step and two-step, and its results were characterized for comparison. Conclusively speaking, two oxide additives were coated onto the $BaTiO_3$ powder surface with high quality and excellent reaction yield even under mild condition, which indicates that the contents as well as the properties of additive shell layer can be precisely controlled with rather ease.

• Polymer(Korea)
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• v.36 no.4
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• pp.531-535
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• 2012

Conductive polyaniline (PANI) nanofibers in UV-curable resin were used for a transparent conductive film. The emeraldine-salt PANI (ES-PANI) nanofibers were prepared by chemical oxidation polymerization of aniline, which could be changed into emeraldine-base PANI by dedoping. EB-PANI nanofibers as a precursor for conductive fillers were thereby transformed into re-dpoed PANI (rES-PANI) by dodecylbenzenesulfonic acid in the UV-curable resin solution. rES-PANI nanofibers have high conductivity and long-term stability in the solution without a defect of nanostructure. The resulting conductive resin solution was proved to be highly stable where no precipitation of rES-PANI fillers was observed over a period of 3 months. The transparent film was spin-casted on a poly(methyl methacrylate) sheet of thickness ca. $5{\mu}m$. A surface resistance of $6.5{\times}10^8{\Omega}/sq$ and transmittance at 550 nm of 91.1% were obtained for the film prepared with a concentration of 1.4 wt% rES-PANI nanofibers in the solution. This transformation process of rES-PANI from ES-PANI by dedoping-redoping can be an alternative method for the preparation of an antistatic protection film with controllable surface resistance and optical transparencies with the PANI concentration in UV-curable solution.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.366-370
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• 2005

Pervaporation process using a NaY zeolite membrane was applied for separation of water generated in an esterification process as a byproduct. From the binary mixture of water and either ethyl acetate or acetic acid and the ternary mixture of water, ethanol and ethyl acetate which might be present in an esterification reaction for manufacturing ethyl acetate, water was separated by the membrane pervaporation. It was investigated how the operating parameters such as an organic concentration and a temperature affected the permeate flux and the separation factor of water. For the feed mixture of water/ethyl acetate, the total flux and the separation factor of water were observed to be $930-5,000g/m^2/hr$ and 3,700-8,000, respectively. Also it was found for ternary mixtures of water/ethanol/ethyl acetate that the total flux was $1,300-3,900g/m^2/hr$ and the separation factor was 530-1,600. A pervaporation process might be applied in an esterification process since both the total flux and the separation factor of water through the NaY zeolite membrane were shown to be very high.

• The Korean Journal of Pesticide Science
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• v.5 no.2
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• pp.1-12
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• 2001

A competitive indirect enzyme-linked immunosorbent assay (ci ELISA) for the organophosphorus insecticide acephate, O,S-dimethyl acetylphosphoramidothioate, was developed using a polyclonal antibody. Three different haptens mimicking the analyze and containing hexanoic acid moiety as a linker were synthesized, and then conjugated with the carrier proteins bovine serum albumin and keyhole limpet hemocyanin by the N-hydroxysuccinimide active ester method. Polyclonal antibodies raised against hapten-KLH conjugates in rabbits and the hapten-BSA conjugates as coating antigens were screened and selected for the assay in the homologous and/or heterologous ELISA system. The effects of various assay conditions, including blocking reagents, detergent content, organic solvents, pH, and preincubation of tile mixture of the polyclonal antibody and the analyze on the sensitivity were evaluated. The $IC_{50}$ value of acephate of 110 ng/mL was obtained in an optimized heterologous system using hapten-3-BSA as a coating antigen and a polyclonal antibody 8377, showing the detection range of 10-1000 ng/mL and the lowest detection limit of 4 ng/mL. The cross-reactivities of the structurally related insecticides, including methamidophos were less than 0.02%. These results indicate that the ELISA could be a convenient and alternative tool for monitoring acephate residues in agricultural products and environmental samples.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.737-741
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• 2005

In this study, the effect of copper content on the NO removal efficiency by Cu/MCM-41 has been investigated. MCM-41 was prepared by hydrothermal synthesis using a gel mixture of colloidal silica solution and cetyltrimethylammonium. Cu/MCM-41 was manufactured with copper content (5, 10, 20, and 40%) in Cu(II) acetylacetonate. The surface properties of MCM-41 were investigated by using pH, XRD, and FT-IR analyses. $N_2/77K$ adsorption isotherm characteristics, including the specific surface area and micropore volume were studied by BET's equation and Boer's t-plot methods. NO removal efficiency was confirmed by gas chromatography technique. From the experimental results, the MCM-41 was analyzed to have the surface functional groups of Si-OH and Si-O-Si and the characteristic diffraction lines (100), (110), (200), and (210) corresponding to a hexagonal arrangement structure. The copper content supported on MCM-41 appeared to increase the NO removal efficiency in spite of decreasing the specific surface areas or micropore volumes. Consequently, it was found that the copper content in Cu/MCM-41 played an important role in improving the NO removal efficiency, which was mainly attributed to the catalytic reactions.

• Korean Journal of Food Science and Technology
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• v.48 no.5
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• pp.424-429
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• 2016

Globally, obesity has been recognized as a serious health problem. Recently, slimming foods for weight loss and maintenance were found to contain anti-obesity drugs, their analogues, and prohibited ingredients. To avoid inspections by the Government, structurally modified analogs have been continuously synthesized. For rapid determination of adulterated slimming products, we simultaneously analyzed 21 illegal compounds using liquid chromatography (LC) equipped with photo diode array, and LC coupled with tandem mass spectrometry. The validation of the method was performed with regard to selectivity, linearity, limit of detection, limit of quantification, precision, and accuracy. We purchased 128 samples from the Korean market and online sources in the year 2015. In 31 samples, 3 illegal compounds were detected as follows: 9.9-135.3 mg/g of sibutramine, 0.2-17.5 mg/g of yohimbine, and 1.8 mg/g of icariin. This simultaneous detection method might prove to be a simple and rapid analysis for monitoring illegal compounds in slimming foods.

• Journal of the Korean Institute of Gas
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• v.2 no.1
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• pp.59-65
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• 1998

Morphology and thermal properties of polyurethane synthesized from 4,4'-diphenylmethane diisocyanate (MDI), polyester polyol, and 1,4-butane diol are investigated using fourier transform infrared spectroscopy (FT-IR), differential scanning calorimeter (DSC), and dynamic mechanical thermal analysis (DMTA). From the FT-IR study, it is found that the stretching peaks of hydrogen bonded N-H and C=O are shifted to the low frequencies with the increase of hard segment content of the polyurethanes. The shift of the stretching peaks of hydrogen bonded N-H and C=O indicates that the degree of hydrogen bonding is increased. From the DSC study, it appears that the glass transition temperature ($T_g$) of the polyurethanes is increased with the increase of the hard segment content. Also, it is found that the polyurethanes investigated in this study have the homogeneous network structure due to the high functionality of the MDI. From the DMTA study, transition of the soft segment was not found. Therefore it is concluded that the polyurethanes investigated in this study have the one-phase morphology which is consistent with the DSC results.