• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.61-64
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• 2003

Optical resolution of a-amino acid (tryptophan and tyrosine) optical isomers was achieved by a pressure driven membrane separation process, using self-supporting crosslinked membranes base on polysaccharide with different swelling indices that ranged from 100 to 70%. The membranes prepared by casting and drying the polymer solution containing 5wt% acetic acid on an acryl plate followed by crosslinking with glutaraldehyde were characterized using such analytical methods as FTIR and swelling index measurements. On the way of separating the optical isomers, several experimental factors such as the concentration of the feed solutions, operating pressure and temperature, and degree of crosslinking of the membranes have been studied. When the chitosan membranes with 70% of swelling index were used , almost complete optical resolution was obtained; 97.92% of enantiomeric excess (ee %) and 2.26 g/$m^2$ㆍh of flux. The operating pressure and the concentration of feed solutions were respectively 1.0 kgf/$\textrm{cm}^2$ and 0.49 mmol/L.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.484-491
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• 2019

An efficient propylene/propane separation technology is needed to obtain high-purity propylene, which is a raw material for polypropylene synthesis. Since conventional cryogenic distillation is an energy-intensive process due to the similar physicochemical properties of propylene and propane, adsorptive separation has gained considerable interest. In this study, we have computationally investigated the changes in adsorption separation performances by arbitrarily controlling the adsorption strength of open metal sites in two different types of metal-organic frameworks (MOFs). Through the evaluation of adsorptive separation performances in terms of working capacity, selectivity, and Adsorption Figure of Merit (AFM), we have suggested proper density and strength of adsorption sites as well as appropriate temperature condition to obtain optimal propylene/propane adsorptive separation performances.

• Membrane and Water Treatment
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• v.13 no.3
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• pp.139-145
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• 2022

Development in advanced separation processes leads to the significant advancement in polymeric membrane preparation methodology. Therefore, present research investigated the preparation and characterization of cellulose acetate membrane by phase inversion separation method to determine optimized operating parameters. Prepared CA membrane's performance was been analyzed in terms of % rejection and flux. Investigation was conducted to study effect of different parameters such as polymer concentration, evaporation rate, thickness of film, coagulation bath properties, temperature of polymer solution and of the coagulation bath etc. CA membrane was fabricated by taking polymer concentration 10wt% and 11wt% with zero second evaporation time and varying film thickness over non-woven polyester fabric. Effect of coagulation bath temperature (CBT) and casting solution temperature were also been studied. The experimental results from SEM showed that the surface morphology had been changed with polymer r concentration, coagulation bath and casting solution temperature, etc. Lower polymer concentration leads to lower precipitation time giving porous membrane. The prepared membrane was tested for advanced waste water treatment of relevant effluent stream in pilot plant to study flux and rejection behavior of the membrane.

• Nuclear Engineering and Technology
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• v.48 no.3
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• pp.719-726
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• 2016

The problem of separation of isotopes in a concurrent gas centrifuge is solved analytically for an arbitrary binary mixture of isotopes. The separative power of the optimised concurrent gas centrifuges for the uranium isotopes equals to ${\delta}U=12.7(V/700m/s)^2(300K/T)(L/1m)kg{\cdot}SWU/yr$, where L and V are the length and linear velocity of the rotor of the gas centrifuge and T is the temperature. This equation agrees well with the empirically determined separative power of optimised counter-current gas centrifuges.

• Journal of the Korean Society for Nondestructive Testing
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• v.12 no.2
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• pp.30-35
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• 1992

High quality of turbine babbit bearing has to be maintained for smooth operation of power plants. So in the research center of the Korea Electric Power Company, Ultrasonic testing has been peformed on the spare part of babbit bearing during past ten years. Since separation between babbit bearing and base metal was seen for most of the bearings in stock, investigation has begun in order to see the effect on temperature and humidity variation of the separation, and thus searching for the optimum storage method.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.398.1-398.1
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• 2002

A new chiral derivatization agent with sugar moiety. 2, 3.4, 6-tetra-O-acetyl-D-galactopyranosyl isothiocyanate (GATC) was synthesized. Several $\beta$-blockers were investigated for the possible separation of the enantiomers by reversed-phase HPLC after derivatization with this new chiral derivatization agent (GATC). GATC was reacted readily with $\beta$-blockers at room temperature and the reaction mixture could directly be injected into the HPLC system. (omitted)

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.275.2-276
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• 2003

Several ${\beta}$-agonists were investigated for the possible separation of the enantiomers by reversed-phase high-performance liquid chromatography after derivatization with a new chiral derivatization agent, GATC. The derivatization proceeded quantitatively within 1 h at room temperature. The corresponding diastereomers were well resolved an ODS column with acetonitrile-acetate buffers a mobile phase and monitored at UV 254nm. (omitted)

• Journal of the Korean Vacuum Society
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• v.12 no.S1
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• pp.100-103
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• 2003

The magnetoresistance (MR) of $La_{1-\chi}S_{\chi}CoO_{3-\delta}$ films prepared by pulsed-laser deposition were investigated in order to clarify the magnetotransport properties around the metal-insulator transition. For the films in the metallic state ($\chi$ > 0.25), the MR(T) manifests a small peak at the Curie temperature due to the spin-disorder scattering. The transition of the film into the insulating state ($\chi\;\leq$ 0.25) is accompanied by an essential growth of the MR and results in a significant increase in the MR(T) with decreasing temperature, due to a phase separation into the ferromagnetic-metal clusters and the insulating matrix.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.2
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• pp.741-751
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• 1996

The coupled conduction and convection heat transfer from the protruding heat source in a vertical channel is numerically investigated. Conjugate solution of the two-dimensional energy equation is obtained for the incompressible air flow over the rectangular block with local heat source. It was found that several recirculation zones and separation bubble near the block were related to Re and Gr. And the results show that fractions of the heat transfer through each of the block face, maximum temperature of the block and the relative effect of each parameter on the maximum temperature and heat transfer.

• Journal of the Korean Society of Industry Convergence
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• v.2 no.2
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• pp.83-90
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• 1999

A cellulose acetate membrane containing silver nitrate was prepared by gelatinizing in water at $2^{\circ}C$ after evaporating solvent from the casting solution on a glass plate. Permeation experiments for oxygen and nitrogen were conducted in the ranges of temperature, $5-40^{\circ}C$ and pressure difference, $1-5kg/cm^2$ in order to investigate the effects of temperature and pressure difference on permeation characteristics of the membrane. When the evaporation time was increased, the permeability of oxygen decreased but the separation factor of oxygen against nitrogen increased since a more dense layer was formed on the membrane surface. When the silver nitrate was added, the permeation flux was doubled and the separation factor was improved from 3.0 to 3.3. This implies that silver nitrate acts as an oxygen carrier in the membrane.