• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1997.05a
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• pp.23-27
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• 1997

Bio-Green(B.G.) functional water was manufactured by Kyungwon Enterprise Co. through a series of processes ; water longrightarrow ultra-purification longrightarrow adding catalysts longrightarrow energy imprinting fermenting with energized water + zeolite and others + photosynthetic bacteria in fermenter longrightarrow filtering. Control(0), 5 or 10 liters of B.G. functional water were supplied to the orchard soil under canopy of 10 year old 'Tsugaru'/M26 apple trees on March 20, May 20 and June 20, 1995, respectively. Some orchard soil characteristics, not only pH, but also Ca and Mg of exchangeable cations were increased by supply with B.G. functional water. However, P$_2$O$_{5}$, K, and B contents were not influenced by the treatment. At harvest time soluble solid content of flesh and anthocyanin of fruit skin were increased by the treatment. B.G. functional water treatment showed higher root activities, and photosynthesis of leaves than that of control. Also B.G. functional water treatment showed higher Ca content in fruit skin and flesh tissues, whereas not affected N, K, and Mg contents. During storage at 4$^{\circ}C$ cold room, the more volume of B.G. functional water supply showed lower bitter pit symptom. Respiration and ethylene evolution in fruit were decreased, while fruit firmness increased by the treatment during storage.e.

• Journal of Soil and Groundwater Environment
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• v.20 no.3
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• pp.83-91
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• 2015

Mine soil contamination by high levels of metal ions that prevents the successful vegetation poses a serious problem. In the study presented here, we used the microbial biocatalyst of urease producing bacterium Sporosarcina pasteurii or plant extract based BioNeutro-GEM (BNG) agent. The ability of the biocatalysts to bioremediate contaminated soil from abandoned mine was examined by solid-state composting vegetation under field conditions. Treatment of mine soil with the 2 biocatalysts for 5 months resulted in pH increase and electric conductivity reduction compared to untreated control. Further analyses revealed that the microbial catalysts also promoted the root and shoot growth to the untreated control during the vegetation treatments. After the Sporosarcina pasteurii or plant extract based BNG treatment, the microbial community change was monitored by culture-independent pyrosequencing. These results demonstrate that the microbial biocatalysts could potentially be used in the soil bioremediation from mine-impacted area.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.462-462
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• 2013

Gallium Oxide (Ga2O3) has been widely investigated for the optoelectronic applications due to its wide bandgap and the optical transparency. Recently, with the development of fabrication techniques in nanometer scale semiconductor materials, there have been an increasing number of extensive reports on the synthesis and characterization of Ga2O3 nano-structures such as nano-wires, nanobelts, and nano-dots. In contrast to typical vaporliquid-solid growth mode with metal catalysts to synthesis 1-dimensional nano-wires, there are several difficulties in fabricating the nanostructures by using sputtering techniques. This is attributed to the fact that relatively low growth temperatures and higher growth rate compared with chemical vapor deposition method. In this study, Ga2O3 chestnut burr were synthesized by using radio-frequency magnetron sputtering method. In contrast to typical sputtering method with sintered ceramic target, a Ga2O3 powder (99.99% purity) was used as a sputtering target. Several samples were prepared with varying the growth parameters, especially he growth time and the growth temperature to investigate the growth mechanism. Samples were characterized by using XRD, SEM, and PL measurements. In this presentation, the details of fabrication process and physical properties of Ga2O3 nano chestnut burr will be reported.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2835-2840
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• 2010

A series of $MoO_3/CeO_2-ZrO_2$ catalysts with different Mo content (8 - 20 wt %) were prepared by simple co-precipitation followed by impregnation method and were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), energy dispersive spectroscopic (EDS) techniques. The prepared materials were tested for catalytic activity by the synthesis of benzimidazole derivatives using condensation of aromatic aldehydes and o-phenylenediamine by conventional and microwave method. Obtained results reveal that the catalytic activity increases with increase in Mo wt % loading. The best catalytic activity was obtained with 20 wt % $MoO_3/CeO_2-ZrO_2$. The particle size or crystallite size was estimated using Debye-Scherrer equation. After completion of reaction, the catalyst can be recovered efficiently and reused with consistent activity.

• Bulletin of the Korean Chemical Society
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• v.28 no.11
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• pp.2056-2060
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• 2007

A successful combination of “oxygen-assisted chemical vapor deposition (CVD) process” and Co catalyst nanoparticles to grow highly pure single walled carbon nanotubes (SWNTs) was demonstrated. Recently, it was reported that addition of small amounts of oxygen during CVD process dramatically increased the purity and yield of carbon nanotubes. However, this strategy could not be applied for discrete Fe nanoparticle catalysts from which appropriate yields of SWNTs could be grown directly on solid substrates, and fabricated into field effect transistors (FETs) quite efficiently. The main reason for this failure is due to the carbothermal reduction which results in SiO2 nanotrench formation. We found that the oxygen-assisted CVD process could be successfully applied for the growth of highly pure SWNTs by switching the catalyst from Fe to Co nanoparticles. The topological morphologies and p-type transistor electrical transport properties of the grown SWNTs were examined by using atomic force microscope (AFM), Raman, and from FET devices fabricated by photolithography.

• Bulletin of the Korean Chemical Society
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• v.25 no.1
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• pp.79-84
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• 2004

The existing technological schemes for processing rhenium-containing raw materials involve the recovery of Re from solutions, which can be effectively achieved by anion exchange method. The application of anion exchange also allows to study rhenium state in aqueous solutions and to develop analytical control methods. The present work is focused on investigation of ion exchange equilibrium in the analytical system Re(VII)-HCl-$SnCl_2$-KSCN-anion exchanger by means of sorption-desorption method as well as by electron, IR- and diffuse reflection spectroscopy. It was shown that rhenium can be quantitatively recovered from this system. It is proposed to use the sorption-spectroscopic method for Re(VII) determination in aqueous solutions. The calibration curve is linear in the concentration range of 0.5-20.0 mg/L (sample volume is 25.0 mL) and the detection limit is 0.05 mg/L. The presence of Mo(VI), Cu(II), Fe(II, III), Ni(II), Zn(II) as well as $K^+,\;Na^+$ do not hinder the solid-phase determination of rhenium. Rhenium (VII) determination by diffuse reflection spectroscopy was carried out in model solutions as well as in samples of river-derived water and in solutions obtained after the dissolution of spent catalysts.

• Korean Journal of Metals and Materials
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• v.48 no.9
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• pp.861-866
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• 2010

Tetrapod-shaped ZnO crystals were synthesized through a simple oxidation of metallic Zn powder in air without the presence of any catalysts or substrates. X-ray diffraction data revealed that the ZnO crystals had wurtzite structure. It is supposed that the growth of the tetrapod proceeded in a vapor-solid growth mechanism. As the amount of the source powder increased, the size of the tetrapod decreased. The tip morphology of the tetrapod changed from a needle-like shape to a spherical shape with the oxidation time. ZnO crystals with rod shape were fabricated via the oxidation of Zn and Sn mixture. Sn played an important role in the formation of ZnO crystals with different morphology by affecting the growth mode of ZnO crystals. The cathodoluminescent properties were measured for the samples. The strongest green emission was observed for the rod-shaped ZnO crystals, suggesting that the crystals had the high density of oxygen vacancies.

• Journal of Powder Materials
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• v.25 no.6
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• pp.514-522
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• 2018

Layered-double hydroxide (LDH)-based nanostructures offer the two-fold advantage of being active catalysts with incredibly large specific surface areas. As such, they have been studied extensively over the last decade and applied in roles as diverse as light source, catalyst, energy storage mechanism, absorber, and anion exchanger. They exhibit a unique lamellar structure consisting of a wide variety of combinations of metal cations and various anions, which determine their physical and chemical performances, and make them a popular research topic. Many reviewed papers deal with these unique properties, synthetic methods, and applications. Most of them, however, are focused on the form-factor of nanopowder, as well as on the control of morphologies via one-step synthetic methods. LDH nanostructures need to be easy to control and fabricate on rigid substrates such as metals, semiconductors, oxides, and insulators, to facilitate more viable applications of these nanostructures to various solid-state devices. In this review, we explore ways to grow and control the various LDH nanostructures on rigid substrates.

• Resources Recycling
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• v.16 no.2 s.76
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• pp.48-55
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• 2007

A low-priced catalyst for pyrolysis of LDPE has been synthesized. Fly ash, which is waste material generated from coal-fired power plants was used as silica and alumna sources for solid acid catalyst. Amorphous silica-alumina catalysts (FSAs) were pre-pared by dissolution of silica and alumina from fly ash, followed by co-precipitation of the dissoluted ions. A series of LDPE pyrolysis were carried out in a thermogravimetric analyzer to investigate the effects of synthesis conditions such as NaOH/fly ash weight ratio and activation time one catalytic performance of FSAs. The physical properties of FSAs were examined and related to their catalytic performances. FSA(1.2-8) synthesized with NaOH/fly ash weight ratio of 1.2 and the activation time of 8 hours showed the best catalytic performance. The catalytic performance of FSA(1.2-8) was comparable with that of commercial catalysts and it was concluded that the FSA could be a good candidate for catalytic use in the recycling of waste polyolefins.

• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.806-811
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• 2016

Organosolv pretreatment is the process to frationation of lignocellulosic feedstocks to enhancement of enzymatic hydrolysis. This process has advantages that organic solvents are always easy to recover by distillation and recycled for pretreatment. The chemical recovery in organosolv pretreatment can isolate lignin as a solid material and carbohydrates as fermentable sugars. For the economic considerations, using of low-molecular-weight alcohols such as ethanol and methanol have been favored. When acid catalysts are added in organic solvent, the rate of delignification could be increased. Mineral acids (hydrochloric acid, sulfuric acid, and phosphoric acid) are good catalysts to accelerate delignification and xylan degradation. In this study, the biomass was pretreated using 40~50 wt% ethanol at $170{\sim}180^{\circ}C$ during 20~60 min. As a results, the enzymatic digestibility of 2-stage pretreatment of rigida using 50 wt% ethanol at $180^{\circ}C$ was 40.6% but that of 1-stage pretreatment was 55.4% on same conditions, therefore it is shown that the pretreatment using mixture of the organosolv and catalyst was effective than using them separately.