• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.128-131
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• 2003

It is well known that the membrane separation process combined with surfactant micelle (micellar-enhanced ultrafiltration) or polyelectrolyte (polyelectrolyte-enhanced ultrafiltration) can remove heavy metals effectively. However, the environmental hazard of surfactant or polyelectrolyte remained in effluent is a serious disadvantage of these methods. In this study, humic substances (HS) were used as complexing agents for metal removal instead of synthetic chemicals. The HS are a sort of natural organic matters which are biodegradable and abundant in natural environment. And the functional groups such as carboxyl groups and phenols in HS can bind with the cationic radionuclides and form complexes. Therefore separation process using them will be more environmental-friendly. The effects of concentration of HS and pH on the removal of cobalt were investigated. The ultrafiltration process was applied to the separation of the cobalt - HS complexes from the aqueous stream. At the concentration of > 3 g/L of HS and pH of 6, over 95 % of cobalt was removed by regenerated cellulose membrane of molecular weight cut-off (MWCO) 3,000. As the concentration of HS increased, the removal of cobalt also was improved because of increase in biding sites (functional groups). The cobalt removal increased from 72.5 % to 97.5 % when pH increased from 4 to 8 at the concentration of 3 g/L HS because of increase in HS solubility and cobalt hydroxide precipitation. In the presence of NaCl, the removal efficiency of cobalt decreased.

• Journal of the Korean Electrochemical Society
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• v.1 no.1
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• pp.18-23
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• 1998

Theoretical model has been derived in the electrophoretic separation system where an electric potential is applied to the system in the axial direction. The effect of electrophoretic convection in the polymeric media is significantly contributed to separate large ionic-molecules because the conformation of large ionic-molecule quickly orients in the field direction. The dependence of the transport in the polymeric media upon field intensity and molecular size aids in understanding the transport of large ionic-molecule in the system, since the convective velocity of large ionic-molecule is accelerated inside a porous material. The separation of two different large ionic-molecules is predicted with a value of $(Pe_t/Pe_g)$ of individual large ionic-molecule using an operator and the reptation theories.

• Bulletin of the Korean Chemical Society
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• v.24 no.7
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• pp.943-947
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• 2003

We have studied the migration behavior of single-stranded DNA using capillary gel electrophoresis under various conditions. It was found that optimum electric fields should be less than 150 V/cm for the good tradeoff between the separation time and the resolution. It seems that the gel matrix with the combination of different polymer average molecular weights is important to extend the maximum readable DNA bases. The total gel concentration less than 3.1% in the mixed gel system showed good separation efficiency up to 600 bases. The best result was obtained with the poy(ethylene)oxide (PEO) gel concentration of 1.2% of Mr 8,000,000 and 1.8% of Mr 600,000. We observed that the capillary length between 50 cm to 100 cm (effective length) should be employed for the optimization between the total DNA migration time and the maximum readable length. A trizma base-boric acid-ethlyenediaminetetraacetic acid (EDTA) (TBE) buffer was commonly used for DNA sequencing, but we found that 3-[tris(hydroxymethyl)methyl amino]-1-propane sulfonic acid (TAPS) buffer worked as well for the single-stranded DNA separation. Especially, TAPS buffer showed a good resolution for very short DNA bases (1 to 30 bases).

• Membrane Journal
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• v.7 no.1
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• pp.22-30
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• 1997

Porous asymmetric membranes were prepared from polyetherimide polymer by the phase-inversion technique under different conditions. The performance of the membranes was tested for the removal of acetone vapour from nitrogen. A membrane which showed a high acetone permeability and a high selectivity was chosen and tested further for the separation of different organic vapours from nitrogen. The molecular structure of organic vapours and the selectivity were correlated. A strong correlation was also found between the chromatographic retention time of the organic vapour and the selectivity. These experimental results led to the conclusion that the sorption is the factor governing the separation of volatile organic compounds from nitrogen. A membrane was also prepared by coating the surface of a porous polyetherimide membrane with silicone rubber. The performance of membranes with and without silicone rubber coating was compared.

• Environmental Engineering Research
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• v.10 no.4
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• pp.155-164
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• 2005

This study investigated the possibility of reducing the residual aluminum (Al) in the treated water using polymers. Two raw waters (lake and river water) and three kinds of polymers (coagulant, flocculant, and filtration aids) were used for this purpose. This study found that coagulation at the high dose did not necessarily lead to the high concentration of the residual Al in the treated water. The coagulation efficacy was found more important in determining the residual Al than the coagulant dose. The use of a polymer enhanced the removal of turbidity as well as the residual Al. The coagulant aid removed the dissolved Al as well as the particulate Al by helping the coagulation and the solid-liquid separation. The flocculant aid and the filtration aid preferentially removed the particulate Al while helping the solid-liquid separation. The filtration aid reduced the residual Al substantially more effectively than the flocculant aid. The polyamine-based coagulant aid (FL) showed the better performance in reducing the residual Al and turbidity than DADMAC (WT). The cationic flocculant aid with weak charge density and the medium molecular weight (SC-020) showed the best performance in reducing the residual Al.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.125-126
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• 2006

We show that thermal rearrangement of glassy polymers below the thermal degradation temperature can create unexpected and large microvoids in the membranes, leading to unexpected high gas permeability with high gas selectivity. These current polymer membranes display unexpected gas permeation-separation performance. There are above the upper-bound for conventional polymer membranes for several gas pairs. In the present study, molecular simulation, BET sorption, positron annihilation lifetime spectroscopy (PALS), and gas separation experiments were performed to characterize the unusual structure-property relationship of these rigid glassy polymer membranes.

• 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.

• Corrosion Science and Technology
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• v.8 no.3
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• pp.103-109
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• 2009

An epoxy coating was designed to give a hydrophobic property on its surface by modifying it with three types of Amino Terminated Polydimethylsiloxane (ATP), and then effects of the modification on the structure, surface hydrophobic tendency, water transport behavior and hence corrosion protectiveness of the modified epoxy coating were examined using FT-IR spectroscopy, hydrothermal cyclic test, and impedance test. The surface of epoxy coating was changed from hydrophilic to hydrophobic property due primarily to a phase separation tendency between epoxy and modifier by the modification. The phase separation tendency is more appreciable when modified by ATP with higher molecular weight ATP at higher content. Water transport behavior of the modified epoxy coating decreased more in that with higher hydrophobic surface property. The resistance to localized corrosion of the modified epoxy coated carbon steel was well agreed with its water transport behavior and hydrophobic tendency.

• Molecules and Cells
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• v.40 no.12
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• pp.889-896
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• 2017

Nuclear bodies are subnuclear, spheroidal, and membraneless compartments that concentrate specific proteins and/or RNAs. They serve as sites of biogenesis, storage, and sequestration of specific RNAs, proteins, or ribonucleoprotein complexes. Recent studies reveal that a subset of nuclear bodies in various eukaryotic organisms is constructed using architectural long noncoding RNAs (arcRNAs). Here, we describe the unifying mechanistic principles of the construction and function of these bodies, especially focusing on liquid-liquid phase separation induced by architectural molecules that form multiple weakly adhesive interactions. We also discuss three possible advantages of using arcRNAs rather than architectural proteins to build the bodies: position-specificity, rapidity, and economy in sequestering nucleic acid-binding proteins. Moreover, we introduce two recently devised methods to discover novel arcRNA-constructed bodies; one that focuses on the RNase-sensitivity of these bodies, and another that focuses on "semi-extractability" of arcRNAs.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.10a
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• pp.62-63
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• 1994

The membrane technology is more convenient and economical way in the separation field than conventional technology such as distillation, extration, crystallization, and so on. Therefore, membrane are used as efficient tools for the separation and concentration of molecular mixture in many industrial area. Although the polymeric membrane have various advantage, they have disadvantages as well. One of them is a poor resistance to organic solvent. Therefore, organic solvent resistant membranes were prepared by soluble polyimide. prepared by phase inversion method. The membranes were The homogeneous polymer solutions were obtained by the two different method ; the one is that the polymer sythesized was completely dissolved in a solvent to prepare a membrane casting solution, the other is that a membrane casting solution was prepared by the unit process from the viscose solution of polymerization.