• Journal of the Korean Wood Science and Technology
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• v.25 no.4
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• pp.68-74
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• 1997

This research was studied dissolving pulp for rayon production, which is not KP, SP methods but steam explosion and oxygen alkali treatment. The variation of characterization in wood cellulose after steam explosion and oxygen alkali treatment this follows. In the oxygen alkali treatment of exploded pine wood, yield of dissolving pulp was lower than steam-exploded oak wood, and we have obtained dissolving pulp that high purity cellulose, but degree of polymerization was inclined to decrease less than 200. In the case of steam-exploded oak wood, degree of polymerization was higher than steam-exploded pine wood but purity of cellulose was lower than its.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.3 no.1
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• pp.23-31
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• 1999

An advanced mobile technology is described for saturating water with oxygen. The MTR(Mass Transfer Reactor) is 2~10 times more effective in dissolving oxygen in water compared to most other systems used in aquaculture, because it can generate extremely small(0.005~0.05mm) bubbles. New fish farming facilities could make use of this technology to build deeper ponds for raising multiple species with optimized conditions for DO(dissolved oxygen), food, light, etc. The proposed technology offers higher DO levels with minimal operating costs. It is easy to use and maintain, with a high reproducibility. Accordingly, the MTR can be industrially applied in the treatment of fish waste and reduction of water consumption during fish farming.

• Journal of Environmental Science International
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• v.24 no.7
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• pp.947-954
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• 2015

Dielectric barrier discharge plasma is a new technique in water pollutant degradation, which that is characterized by the production of chemically active species such as hydroxyl radicals, ozone, hydrogen peroxide, etc. If dissolving of plasma gas generated in the plasma reaction has increased, it is possible to increase the contaminant removal capacity. In this study, the improvement on the dissolving performance of plasma gas was evaluated by the indirect method measuring the overall oxygen transfer coefficient. Experiments were conducted to examine the effects of nozzle type, distance from water surface, air supply rate and liquid circulation rate. The experimental results showed that the $K_{La}$ value of the 3-prong nozzle is 2.67 times higher than the diffuser. The order of $K_{La}$ value with nozzle type ranked in the following order: 3-prong nozzle (inner diameter, less 1 mm) > circular nozzle (inner diameter, 1.5 mm) > ellipse nozzle (short diameter 1 mm, long diameter 2.5 mm) > circular nozzle (inner diameter, 3 mm). Optimal liquid circulation rate was appeared to be 1.7 L/min, the value of $K_{La}$ was 0.510 1/min. The value of $K_{La}$ with increasing air supply rate was revealed in the form of an exponential such as $K_{La}=0.3581e^{0.2919^*air\;flow\;rate}$.

• Rapid Communication in Photoscience
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• v.2 no.3
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• pp.72-75
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• 2013

Bulk nanobubble is one of the nanoscopic gaseous state found in the solution. We measured transient absorption spectra of eosin Y in the excited triplet state ($^3EY^{2-*}$) to elucidate differences in the dissipation process of the bulk nanobubble of oxygen molecule at air pressure. The time dependence of the oxygen dissipation process was classified three time domains (P1, P2 and P3). The comparison of ordinary bubbling method gave different results at P3 in contrast to similar results at P1 and P2, indicating the existence of characteristic dissolving state in the case of nanobubble.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.463-465
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• 1998

The peculiarities of the polyvinylpyrrolydone (PVP) interaction with transition metal ions of the first row in solution were studied. It was shown that PVP macromolecules due to their swelling conformation in organic solvents form the stable metal complexes. Metal ions were bond with oxygen and nitrogen atoms of PVP lactam rings. In water solution every metal ion interacts with one or two oxygen atoms out of 10-12 monomer units of the polymer. The additional contraction of PVP macromolecule coils in water have been found out by dissolving of the polymer metal complexes (PMC) synthesized in organic media. Toxicity, blood forming and immune stimulating activity and pharmaco-kinetic too of obtained polymers and their metal completes have been investigated. The factors and effects that responsible fur changing of PMC physical-chemical and biological properties have been estimated.

• Environmental Engineering Research
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• v.16 no.2
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• pp.97-102
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• 2011

This study investigates the treatment of pigment wastewater using a sequential batch reactor (SBR) followed by dissolved ozone flotation-pressurized ozone oxidation treatement (DOF-$PO_2$). The process efficiency has been evaluated at the lab scale on the basis of water quality parameters. In addition, the effect of pure oxygen and air was investigated on the removal of COD, BOD, and TN in the SBR process. It was observed that under comparable conditions the removal efficiencies of these water quality parameters using pure oxygen and air were similar. The effect of the recycle rate was also investigated for its impact on the water quality parameters using different ozone dissolving pressures in a DOF process in order to optimise conditions. The results conclude that the use of an SBR and ozone contact by DOF-$PO_2$ is a highly effective treatment for pigment wastewater and aids in the achievement of effluent discharge criteria.

• Corrosion Science and Technology
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• v.6 no.6
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• pp.304-307
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• 2007

As to the reflection electrode of LCD (liquid crystal displays), silver-copper-gold alloy (hereafter, it is called as ACA (Ag98%, Cu1%, Au1%)) is an effective material of which weathering resistance can be improved more compared with pure silver. However, there is a problem that gold remains on the substrate as residues when ACA is etched in cerium ammonium nitrate solution or phosphoric acid. Gold can not be etched in these etchants as readily as the other two alloying elements. Gold residue has actually been removed physically by brushing etc. This procedure causes damage to the display elements. Another etchant of iodine/potassium iodide generally known as one of the gold etchants can not give precise etch pattern because of remarkable difference in etching rates among silver, copper and gold. The purpose of this research is to obtain a practical etchant for ACA alloy. The results are as follows. The cyanogen complex salt of gold generates when cyanide is used as the etchant, in which gold dissolves considerably. Oxygen reduction is important as the cathodic reaction in the dissolution of gold. A new etchant of sodium cyanide / potassium ferricyanide whose cathodic reduction is stronger than oxygen, can give precise etch patterns in ACA alloy swiftly at room temperature.

• Journal of Powder Materials
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• v.25 no.5
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• pp.390-394
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• 2018

Metallic tantalum powder is manufactured by reducing tantalum oxide ($Ta_2O_5$) with magnesium gas at 1,073-1,223 K in a reactor under argon gas. The high thermodynamic stability of magnesium oxide makes the reduction reaction from tantalum oxide into tantalum powder possible. The microstructure after the reduction reaction has the form of a mixture of tantalum and magnesium oxide, and the latter could be entirely eliminated by dissolving in weak hydrochloric acid. The powder size in SEM microstructure for the tantalum powder increases after acid leaching in the range of 50-300 nm, and its internal crystallite sizes are observed to be 11.5 to 24.7 nm with increasing reduction temperatures. Moreover, the optimized reduction temperature is found to be 1,173 K as the minimum oxygen concentration is approximately 1.3 wt.%.

• Progress in Superconductivity
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• v.8 no.1
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• pp.59-64
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• 2006

High $J_c\;YBa_2Cu_3O_x$ superconducting films were fabricated by MOD method using fluorine-free dichloroacetic acid(DCA) as chelating solvent for preparing precursor solution. Coating solutions were prepared by dissolving Y-, Ba- and Cu-acetates in DCA solvent followed by drying in rota vapor to obtain the blue gel that is diluted in methanol and 2-methoxyethanol for adjusting the cation concentration. DCA-MOD precursor solution was coated on a single crystal(001) $LaAlO_3(LAO)$ substrate by a dip coating method with a speed of 25 mm/min. Coated films were calcined at lower temperature up to $500^{\circ}C$ in flowing oxygen atmosphere with a 7.2% humidity. Conversion heat treatment was performed at various temperatures of $780{\sim}810^{\circ}C$ for 2 h in flowing Ar gas containing 1000 ppm oxygen with a humidity of 9.45%. SEM observations showed that films have very dense microstructures for the films prepared at the temperature higher than $800^{\circ}C$ regardless of diluting solvent; methanol or 2-methoxyethanol. X-ray diffraction analysis showed that YBCO grains grew with a (001) preferred orientation. A High critical current density($J_c$) of 1.28 $MA/cm^2$(@77 K and self-field) was obtained id. the YBCO film prepared using 2-methoxyethanol as a solvent.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.4
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• pp.464-471
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• 2002

Porosity formation in partial penetration welds by high power lasers is a serious problem in industry. There are two main causes that induce porosity formation. One form of porosity is due to gases (e.g. hydrogen, oxygen) dissolving into the weld pool because of the high temperature and then the rapid solidification traps gases as a bubble in the weld metal. The second problem is voids formed by the keyhole collapsing due to unstable keyhole fluid dynamics. The voids that form at the bottom of the keyhole are relatively large and irregular in shape compared to the gas bubbles; this void formation is the primary concern in this paper. The reduction of voids formed by keyhole collapse is achieved by improving the stability of keyhole. Two methods to improve keyhole stability are discussed in this paper: pulse modulation and beam incident angle. Pulse modulation of the laser beam was performed between 100 Hz and 500 Hz to find out the optimum frequency for the keyhole dynamics. The incident beam angle changed the impact angle of the laser beam to the work surface in a range of 0 to 25 degrees. Glycerin in a semi-solidified state is used as a medium for performing the welding because its transparency allows of visualization of the keyhole.