• Membrane Journal
• /
• v.30 no.4
• /
• pp.260-268
• /
• 2020

Mixed-matrix carbon molecular sieve membranes containing conventional and hierarchically structured 5A were synthesized for application in oxygen (O₂)/nitrogen (N₂) separation. In general, incorporating 5A fillers into porous carbon matrices dramatically increased the permeability of the membrane with a marginal decrease in selectivity, resulting in very attractive O₂/N₂ separation performances. Hierarchical zeolite 5A, which contains both microporous and mesoporous domains, improved the separation performance further, indicating that the mesopores in the zeolite can serve as an additional path for rapid gas diffusion without sacrificing O₂/N₂ selectivity substantially. This facile strategy successfully and cost-effectively pushed the performance close to the Robeson upper bound. It produced high performance membranes based on Matrimid^® 5218 polyimide and zeolite 5A, which are inexpensive commercial products.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.32 no.1
• /
• pp.78-85
• /
• 2019

The effect of various lithium sources such as LiCl, LiOH, and Li-metal on the microstructure and electrochemical properties of granulated $SiO_x$ powders were investigated. Various lithium sources were metallurgically added for a passive pre-lithiation of $SiO_x$ to improve its low initial coulombic efficiency. In spite of using the same amount of Li in various sources, as well as the same process conditions, different lithium silicates were obtained. Moreover, irreversible phases were formed without reduction of $SiO_x$, which might be from additional oxygen incorporation during the process. Accordingly, there were no noticeable electrochemical enhancements. Nevertheless, the $Li_4SiO_4$ phase changes the initial electrochemical reaction, and consequently the relationship between the microstructure and electrochemical properties of metallurgically pre-lithiated $SiO_x$ could provide a guideline for the optimization of the performance of lithium ion batteries.

• Applied Microscopy
• /
• v.42 no.3
• /
• pp.151-157
• /
• 2012

The microstructure of various shapes of stacking fault pyramids (SFPs) formed in multiple implant/anneal Separation by Implanted Oxygen (SIMOX) material were investigated by plan-view and cross-sectional transmission electron microscopy. In the multiple implant/anneal SIMOX, the defects in the top silicon layer are confined at the interface of the buried oxide layer at a density of ${\sim}10^6\;cm^{-2}$. The dominant defects are perfect and imperfect SFPs. The perfect SFPs were formed by the expansion and interaction of four dissociated dislocations on the {111} pyramidal planes. The imperfect SFPs show various shapes of SFPs, including I-, L-, and Y-shapes. The shape of imperfect SFPs may depend on the number of dissociated dislocations bounded to the top of the pyramid and the interaction of Shockley partial dislocations at each edge of {111} pyramidal planes.

• Environmental Engineering Research
• /
• v.21 no.4
• /
• pp.393-400
• /
• 2016

The aim of this study was to evaluate the biomass production and dairy wastewater treatment using Chlorella vulgaris. The results indicated that the maximum percentages of biochemical oxygen demand, chemical oxygen demand, suspended solids, total nitrogen, and total phosphorus removed were 85.61%, 80.62%, 29.10%, 85.47%, and 65.96%, respectively, in dairy effluent at 10 d. A maximum of 1.23 g/L dry biomass was obtained in 7 d. The biomass productivity was strongly influenced by the nutrient reduction in the dairy effluent. The biodiesel produced by the C. vulgaris in the dairy effluent was in good agreement with the American Society of Testing and Materials-D6751 and European Standards 14214 standards. Therefore, using dairy effluent for microalgal cultures could be a useful and practical strategy for an advanced, environmentally friendly treatment process.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.29 no.1
• /
• pp.43-51
• /
• 1997

The various culture conditions of Trichoderma viride(ATCC 3454) and Phanerochaete chrysosporium(ATCC 26921) with glucose-pepton medium, Mandels medium, YMG medium for wood degradable enzyme were examined. Mycellium of the two species grew profusely on glucose-pepton medium. Maximum fungal growth was observed about 10days. But CMCase, Fpase, laccase activity in the culture medium with glucose-pepton was not detected. When grown in fermenter culture using Mandels medium, Trichoderma viride produced CMCase and Fpase. Its CMCase activity was 0.15 lU/ml and Fpase activity was 0.3 IU/ml within about 4-6days. Phanerochaete chrysosporium grown in a YMG medium gave the best enzyme activity when they were grown under stationary culture with an atmosphere of 100% oxygen. Levels of laccase activity of 3.0 mull were achieved in stationary culture under 100% oxygen. The enzyme condensation by ultrafiltration method caused a 2-fold(cellulase) and 6-fold(laccase) as compared to control activity.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.12
• /
• pp.1814-1818
• /
• 2003

$Li^+$ and $H^+$ co-exchanged LSXs (Li-H-LSX) with various ratios of $Li^+$ and $H^+$ were prepared, and those adsorption characteristics of nitrogen and oxygen were compared with Li-Na-LSX and Li-Ca-LSX. Li-H-LSX showed higher nitrogen capacity and selectivity than that of Li-Na-LSX in the wide range of Li-exchanged ratio. The nitrogen capacity of Li-Ca-LSX was slightly higher than that of fully Li- or Ca-exchanged LSX (Li- LSX or Ca-LSX). However, Li-Ca-LSX showed low nitrogen/oxygen adsorption selectivity until the Li content reached about 80%, which was a tendency near that of Ca-LSX.

• Journal of Environmental Science International
• /
• v.18 no.11
• /
• pp.1283-1289
• /
• 2009

Eco-physiological research and the control of Cochlodinium polykrikoides was carried out to elucidate eco-physiological characteristics of red tide organism through culture experiment depending on the condition of photon irradiance. Oxygen consumption of C. polykrikoides was high with a value of 1.12 mg/L/hr in the dark compared with that of 0.13 mg/L/hr at $100{\mu}mEm^{-2}s^{-1}$. DO values in a circular chamber with the lapse of time in seawater containing C. polykrikoides were declined in the dark period. DO values of seawater containing C. polykrikoides in the dark were declined from 7.01 mg/L to 2.65 mg/L in 30 cm depth and from 7.01 mg/L to 6.63 mg/L in 5 cm depth depending on the depth of circular culture vessel. Olive flounder, Paralichthys olivaceus and file fish, Stephanolepis cirrhifer exposed to Cochlodinium showed the separation of the lamella epithelium from gill filament, which disrupted the respiratory process at the gill level.

• Nuclear Engineering and Technology
• /
• v.53 no.6
• /
• pp.1931-1938
• /
• 2021

Uranium ingot is produced by metallothermic reduction of uranium tetrafluoride using magnesium or calcium as reductant. Presence of oxygen containing compounds viz. uranyl fluoride and uranium oxide in the starting uranium fluoride has a significant effect on the firing time, final temperature of the charge, slag-metal separation and hence the metal recovery. As reported in the literature, the maximum tolerable limit for uranyl fluoride in the UF₄ is 2.5 wt% and limit for uranium oxide content is in the range 2-3 wt%. No theoretical or experimental basis is available till date for these limits. Analyses have been carried out in this study to understand the effect of UO₂F₂ concentration in the starting fluoride on the final temperature of the products and thus the reduction characteristics. UF₄ having uranyl fluoride concentration, less than as well as more than 2.5 wt%, have been investigated. Thermodynamic calculations have been carried out to arrive at a general expression for the final temperature attained by the products during calciothermic reduction of UF₄. Finally, an upper limit for the oxygen containing impurities has been estimated using the CaO-CaF₂ phase diagram.

• Proceedings of the Korean Nuclear Society Conference
• /
• 2004.10a
• /
• pp.1267-1268
• /
• 2004

• Proceedings of the Membrane Society of Korea Conference
• /
• 2004.05b
• /
• pp.147-152
• /
• 2004

Gas separation membrane technology is useful for a variety of applications [1, 2]. such as hydrogen recovery from reactor purge gas, nitrogen and oxygen enrichment, water vapor removal from air, stripping of carbon dioxide from natural gas. etc. Although membrane separations are attractive because of low energy costs and simple operation, low permeabilities and/or selectivity often limit membrane applications [3, 4].(omitted)