• Journal of Powder Materials
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• v.6 no.3
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• pp.238-245
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• 1999

The preparation of $n-TiO_2$ powder by the Chemical Vapor Synthesis process (CVS) was studied using the liquid metal organic precursor (TTIP). The residence time and the collection methods were considered as main processing variables through the experiments. The CVS equipment consisted of a micropump and a flashvaporizer, a tube furnace and a tubular collection device. The synthesis was performed at $1000^{\circ}C$ with various sets of collection zone. The residence time and the total system pressure were controlled in the range of 3~20 ms and 10 mbar, respectively. Nitrogen adsorption, X-ray diffraction and electron microscopy were used to determine particle size, specific surface area and crystallographic structure. The grain size of the as-prepared $n-TiO_2$ powder was in the range of 2~8 nm for all synthesis parameters and the powder exhibited only little agglomeration. The relationship between particle characteristics and the processing variables is reviewed based on simple growth model.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2011.04a
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• pp.31-35
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• 2011

Factors influencing penetration kinetics of PVAm solution into paper were investigated with ultrasonic Penetration Evenness Analyzer (PEA). Paper structure was varied by changing basis weight, freeness of pulp, calendering, number of plies and filler addition and hydrophobicity of paper was varied by adding AKD. Important factors affecting liquid penetration are found to be pore structure and hydrophobicity of paper. Pore structure of paper can be designed by controlling refining degree and filler addition. Hydrophobicity of paper can be controlled by internal sizing.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.10a
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• pp.5-8
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• 1997

Introduction : Membranes made from inorganic materials are generally superior to organo-polymeric materials in thermal and mechanical stability, and chemical resistance. Among inorganic materials zeolite is a promising candidate for a high performance membrane because of the unique characteristics of zeolite crystals such as molecular sieving, ion exchange, selective adsorption and catalysis. Although there are many recent reportsl on the preparation of zeolitc membranes and the gas permeation through the membranes, only a limited number of publications deal with pervaporation studies. Recently, we have reported a high pervaporation performance of NaA zeolite membrane for the separation of water/organic liquid mixtures. and of NaY zeolite menlbrane for the separation of methanol/MTBE. Here, preparation of zeolite (LTA, ZSM-5 and FAU) membranes and their permeation properties are discussed.

• Applied Chemistry for Engineering
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• v.5 no.1
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• pp.105-113
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• 1994

The amount of nitrogen gas adsorbed by Spherocarb and Sucrose Char was measured as a function of the relative pressure with temperature being kept constant at 77 to 184K. Isotherms at different temperatures were obtained by keeping the adsorbent at a constant temperature using liquid nitrogen, iso-pentane, n-pentane, ethyl alcohol, and iso-propyl alcohol slush baths. The objective for this study is to provide information on the specific surface area and pore volume by analyzing the experimental data using adsorption models such as the Brunauer-Emmett-Teller and Dubinin-Radushkevich models.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.767-770
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• 2000

A novel process is newly developed for building RP(Rapid Prototyping) parts using a sheet lamination technique. The build process of existing sheet lamination type RP machines consists of the following steps : feeding, lamination and cutting. In this process, the laminated part of an object is often scratched by a cutter or damaged by a laser beam due to the cutting operation preceded by lamination, In addition, decubing of the unused portion from the laminated block is difficult. In the new process, cutting operation is performed before lamination. The cutting operation takes place while a paper sheet is firmly attached on the plate using electrostatic force. Then liquid glue is applied to the calculated region of the given contour for lamination. The process aims to manufacture a $2k RP machine, what we call the Freeform Mater I, that can use A4 or latter-size used papers. A prototype machine that demonstrates the design concept is built and further research issues are discussed.

• The Korean Journal of Nuclear Medicine
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• v.7 no.1
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• pp.51-54
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• 1973

The use of ion-exchange resins for the treatment of radioactive wastes has many advantages, but thes eare rather expensive as compared with the Korean vermiculite. The Korean vermiculite has slightly different chemical constituents from the ones produced in other countries, and its physical properties might be applicable to the management of radioactive waste, in a small nuclear installation. The decontaminating effect of Korean vermiculite for the low-level radioactive liquid was investigated. $^{106}Ru,\;^{90}Sr,\;and\;^{137}Cs$ were utilized for the experiments. The removal rates by Korean vermiculite were calculated for $^{106}Ru,\;^{90}Sr\;and\;^{137}Cs$ and the removal rates increased as the weight of vermiculite in the exchange column increased. The decontaminating constants, $K_d$ of the Korean vermiculite for $^{106}Ru,\;^{90}Sr\;and\;^{137}Cs$ were 2.7, 69.3 and 263ml/g respectively. Through the results of experiments, the application of Korean vermiculite column to the treatment of low-level radioactive waste is quite feasible.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.318-318
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• 2011

Etching of an ultrathin aluminum oxide film on NiAl(110) substrate by methanol is studied by home-built scanning tunneling microscopy at room-temperature. We deposited liquid methanol on thin alumina film by using a high speed solenoid valve suitable for deposition of thermally unstable molecules. It is found that only the reflection domain boundary between two domains was preferentially etched by methanol. Since the reflection domain boundary has many oxygen vacancies and irregular structures, judging from the fact, we assume that oxygen vacancies cause the chemically reactive phenomena of methanol in reflection domain boundary on an alumina film. The reactivity of the reflection domain boundary is attributed to the oxygen vacancies due to irregular structures. Similar reactivity is found on the oxygen deficient alumina produced on top of the intact alumina.

• KSBB Journal
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• v.15 no.5
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• pp.464-468
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• 2000

The methanol extract of Arachis hypogaea shell showed antioxidative and antimicrobial activity. The methanol extract was successively purified by solvent fractionation, silica gel adsorption column chromatography, Sephadex LH-20 column chromatography and octadecylsilane column chromatography. The purified active substances were isolated by high performance liquid chromatography, and were identified as 3-methoxy-4-hydroxybenzoic acid and 4-hydroxybenzoic acid by LC-MS and GC-MS. The amount of 3-methoxy-4-hydroxybenzoic acid and 4-hydroxybenzoic acid were 3.8mg and 9.8 mg per kg of shell, respectively.

• Journal of the Korean Wood Science and Technology
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• v.10 no.4
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• pp.38-52
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• 1982

The effect of propylene oxide, butylene oxide, furan resin, and vinylpyrrolidinone in controlling wood dimensional stability have been examined. Wood in the green or ovendry condition was treated with various chemical treatments using a vacuum-pressure procedure, and treated specimens were tested for tangential sweelling, moisture gain, and changes in sorption hysteresis. Results' indicate that propylene oxide, and butylene oxide enhanced with the crosslin king agent trimethylol propane trimethacrylate and applied to ovendry wood were the most efficient chemical treatments in controlling tangential sweeling caused by liquid water or water vapor, and in reducing water vapor adsorption. The sorption behavior of treated wood as depicted by the ratios of sorption was "very favorable" in most instances. In the particular case of furan resin treatments, ratios of sorption were improved from 25 to 100 percent as compared to those of untreated wood.

• Geomechanics and Engineering
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• v.17 no.2
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• pp.157-164
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• 2019

The effect of electrochemical modification of the physical and mechanical properties of sandstone from Paleozoic coal measure strata was investigated by means of liquid nitrogen physical adsorption, X-ray diffraction and uniaxial compressive strength (UCS) tests using purified water, 1 mol/L NaCl, 1 mol/L $CaCl_2$ and 1 mol/L $AlCl_3$ aqueous solution as electrolytes. Electrochemical corrosion of electrodes and wire leads occurred mainly in the anodic zone. After electrochemical modification, pore morphology showed little change in distribution, decrease in total pore specific surface area and volume, and increased average pore diameter. The total pore specific surface area in the anodic zone was greater than in the cathodic zone, but total pore volume was less. Mineralogical composition was unchanged by the modification. Changes in UCS were caused by a number of factors, including corrosion, weakening by aqueous solutions, and electrochemical cementation, and electrochemical cementation stronger than corrosion and weakening by aqueous solutions.