• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.194-201
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• 2005

Nanoscale fabrication of silicon substrate in an aqueous solution based on the use of atomic force microscopy was demonstrated. A specially designed cantilever with diamond tip, allowing the formation of damaged layer on silicon substrate easily by a simple scratching process (Tribo-Nanolithography, TNL), has been applied instead of conventional silicon cantilever for scanning. A slant nanostructure can be fabricated by a process in which a thin damaged layer rapidly forms in the substrate at the diamond tip-sample junction along scanning path of the tip and simultaneously the area uncovered with the damaged layer is being etched. This study demonstrates how the TNL parameters can affect the formation of damaged layer and the shape of 3-D structure, hence introducing a new process of AFM-based nanolithography in aqueous solution.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.1
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• pp.39-46
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• 2015

The degradation characteristics of perchloroethylene by ferrate(VI) oxidation have been studied. The degradation efficiency of perchloroethylene in aqueous solution was investigated at various values of ferrate(VI) dosage, pH, initial concentration of perchloroethylene and aqueous solution temperature. GC-ECD has been used to analyze the changes of perchloroethylene concentration. The optimum conditions of perchloroethylene degradation were obtained at pH 7.0 and $25^{\circ}C$ of aqueous solution temperature. Also, the experimental results showed that perchloroethylene removal efficiency increased with the decrease of initial concentration of perchloroethylene. Lastly intermediate products were identified by GC-MS techniques. Trichloroethylene and chloroform were identified as reaction intermediates.

• Journal of the Korean Wood Science and Technology
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• v.37 no.5
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• pp.480-485
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• 2009

Juglans mandshurica bark was collected and extracted with 70% aqueous acetone. The extracts were concentrated and then sequentially fractionated using n-hexane, $CH_2Cl_2$, EtOAc, and $H_2O$ to be freeze dried. A portion of $H_2O$ fraction was chromatographed on a Sephadex LH-20 column using aqueous methanol to isolate (S)-2,3-HHDP-D-glucopyranoside (1). Some of EtOAc fraction was also treated on a Sephadex LH-20 column using aqueous methanol and EtOH-hexane mixture to purify pedunculagin (2). The structures of these two epimeric ellagitannins were elucidated by spectroscopic tools, NMR and MS.

• International Journal of Precision Engineering and Manufacturing
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• v.7 no.4
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• pp.8-13
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• 2006

Nanoscale fabrication of silicon substrate in an aqueous solution based on the use of atomic force microscopy was demonstrated. A specially designed cantilever with a diamond tip, allowing the formation of a mask layer on the silicon substrate by a simple scratching process (Tribo-Nanolithography, TNL), has been applied instead of the conventional silicon cantilever for scanning. A slant nanostructure can be fabricated by a process in which a thin mask layer rapidly forms on the substrate at the diamond tip-sample junction along scanning path of the tip, and simultaneously, the area uncovered with the mask layer is etched. This study demonstrates how the TNL parameters can affect the formation of the mask layer and the shape of 3-D structure, hence introducing a new process of AFM-based nanolithography in aqueous solution.

• Korean Journal of Microbiology
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• v.13 no.2
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• pp.64-70
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• 1975

As a serial experiment of radiosterilization of medical products, we investigated the feasibility of using gamma ray to sterilize antibiotics, tetracycline HCl. Tetracycline HCl in aqueous solution and dried state irradiated with several dose levels was assayed for physico-chemical properties by checking UV absorption spectra, paper chromatogrph. IR spectra and NMR sepctra, and antibiotic activities by [means of agar plaque technique and tube $d_1$]ution method. In physico-chemical propertis and biological activities, the teracycline HCl in dried state remained radioresistant up to exposure of 10 Mrad, however, in aqueous solution, the dose of 300 Krad produced a significant inactivation. From the results of this study, radiosterilization of tetracycline HCl is more recommendable in the dried state than in aqueous solution.

• Korean Journal of Materials Research
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• v.13 no.9
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• pp.625-630
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• 2003

Increasing environmental concerns require to solve the problem produced due to the use of heavy metals in coating formulations. Therefore, it is necessary to develop new coating strategy employing inherently conducting polymers such as Polyaniline(PANI). Polyaniline films were electrosynthesized by oxidation of aniline on cold rolled and weathering sheets using the potentiostatic mode from an aqueous oxalic acid medium. Potentiodynamic polarization curves were obtained for cold rolled and weathering sheets in the aqueous solution of 3% sodium chloride. The structure and properties of polyaniline film were elucidated using SEM, DSC, SST. A high corrosion resistance of polyaniline films were observed with a gain of the corrosion potential around 600-900 mV positive in the substrate covered with polyaniline than in the case without it.

• Journal of Pharmaceutical Investigation
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• v.39 no.5
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• pp.353-357
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• 2009

As a synthetic analog of the naturally occurring hormone somatostatin, octreotide has been commercially formulated in poly(lactide-co-glycolide) (PLGA) microspheres for the treatment of acromegaly. The purpose of this study was to evaluate stability of octreotide acetate in aqueous solutions at various pH values and PLGA films. Stability-indicating reversed-phase high-performance liquid chromatographic method was developed with good precision and accuracy, and it was applied to the stability studies. In aqueous solutions at pH 2.5-9.0, the degradation of octreotide followed approximately first order kinetics and the most favorable stability was found at pH 4. In PLGA films, the formation of acylated octreotides reached approximately 55% of the released octreotides. Various acylated octreotides was structurally identified by liquid chromatography-mass spectrometric analysis.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.299-306
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• 2009

The purpose of this study was to prepare stable water-in-corn oil (W/O) emulsion droplets coated by polyglycerol polyricinoleate (PGPR). W/O emulsions (20 wt% aqueous phase, 80 wt% oil phase containing 8 wt% PGPR) were produced by high pressure homogenization (Emulsions 1), however, appreciable amount of relatively large water droplets (d>$10{\mu}m$) were found. To facilitate droplet disruption, viscosity of each phase was adjusted: (i) increased the viscosity of aqueous phase by adding 0.1 wt% xanthan (Emulsions 2); (ii) decreased the viscosity of oil phase and aqueous phase by heating them separately at $50^{\circ}C$ for 1 hr immediately before emulsification (Emulsions 3). Homogenizing at the elevated temperature clearly led to a smaller water droplet size, whereas xanthan neither improved nor adversely affected on the microstructures of the emulsions. In addition, the Emulsions 3 had good stability to droplet aggregation under shearing stress, thermal processing, and long term storage.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.12 no.1
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• pp.17-33
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• 1986

The interfacial Properties of ferrosoferric oxide suspended in aqueous KNO3 solution are investigated by studying the zeta potentials and surface charge densities at $25^{\circ}C$. The zeta potentials are obtained by measuring the electrophoretic mobility and the surface charge densities by potentiometric titrations in the aqueous KNO3 solutions of different concentrations from 10-3 to 10-1M. The data are interpreted by the surface dissociation and complexation model of Davis, et als. and the modified model.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.12 no.1
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• pp.34-61
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• 1986

The microstructural transitions of aqueous micellar solutions of cetyltrime-thylammonium bromide and sodiumdodecyl sulfate by adding 1-hexanol were investigated, measuring the concentrations of equilibrated phases and the electrical conductivities at the low concentrations of surfactants, where the solobilities of 1-hexanol varied significantly, at 3$0^{\circ}C$ and 45$^{\circ}C$. Ternary phase diagrams of multiphase regions, constructed by liquid chromatography analysis and by counting the number of phase of samples, consisted of one three-phase region and three two-phase regions. One of the two-phase regions was found to equilibrate an aqueous micellar solution and a liquid crystal, and had a critical point between them. Near this region, the solubility curve varied abruptly, and the isotropic solution turned birefrigent. The conductivities of the single phase regions above the critical point increased up to a certain point as 1-hexanol added, and then decreased, representing the microstructural transition at the supercritical region. Further, the solubility of 1-hexanol in aqueous micellar solution was found to increase as temperature and the number of hydrophilelipophile balance of surfactants increase.