• Korean Chemical Engineering Research
• /
• v.48 no.2
• /
• pp.212-217
• /
• 2010

In this study, suspension polymerized toners were prepared by using poly(vinyl alcohol)(PVA) as an organic suspending agent. Styrene and butylacrylate monomers were used simultaneously with carbon black to prepare microspherical polymerized toners with a narrow-particle size distribution. Preliminary particles without carbon black were polymerized first to optimize suspension polymerization conditions. The preliminary particles were prepared at various polymerization conditions and their characteristics were compared to each other to determine an optimized polymerization condition. The black polymerized toner prepared at the optimized polymerization condition showed reasonable particle size and shape, and good thermal and printing characteristics by showing its glass transition temperature at $53.6^{\circ}C$.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.2
• /
• pp.608-612
• /
• 2012

We investigated the cycling behavior of $Li_4Ti_5O_{12}$ electrode in a cross-linked gel polymer electrolyte based on non-flammable ionic liquid consisting of 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide and vinylene carbonate. The $Li_4Ti_5O_{12}$ electrodes in ionic liquid-based gel polymer electrolytes exhibited reversible cycling behavior with good capacity retention. Cycling data and electrochemical impedance spectroscopy analyses revealed that the optimum content of the cross-linking agent necessary to ensure both acceptable initial discharge capacity and good capacity retention was about 8 wt %.

• Journal of Microbiology and Biotechnology
• /
• v.30 no.1
• /
• pp.31-37
• /
• 2020

We previously identified a new heparinase inhibitor fungal metabolite, named CRM646-A, which showed inhibition of heparinase and telomerase activities in an in vitro enzyme assay and antimetastatic activity in a cell-based assay. In this study, we elucidated the mechanism by which CRM646-A rapidly induced nucleus condensation, plasma membrane disruption and morphological changes by increasing intracellular Ca²⁺ levels. Furthermore, PD98059, a mitogen-activated protein kinase (MEK) inhibitor, inhibited CRM646-A-induced nucleus condensation through ERK1/2 activation in rat 3Y1 fibroblast cells. We identified CRM646-A as a Ca²⁺ ionophore-like agent with a distinctly different chemical structure from that of previously reported Ca²⁺ ionophores. These results indicate that CRM646-A has the potential to be used as a new and effective antimetastatic drug.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2017.05a
• /
• pp.156-157
• /
• 2017

It is possible in the case of the chemical admixtures for concrete currently being used in actual work sites to omit quality evaluation and replace it with the scores of the admixture manufactures; this can create a problem of decline in reliability in quality on the work site. Therefore this study sought to analyze the degree of influence changes in the solid content rate of lignin- and naphthalene-based water-reducing agents have on the fundamental characteristics of cement mortar. The results showed that in fresh mortar, the flow and amount of air decreases with decrease in the solid content ratio. In hardened mortar, the condensation strength had hardly any effect on the use of lignin-based water-reducing agent, but naphthalene-based water-reducing agent increased with the decrease in the solid content ratio.

• Applied Chemistry for Engineering
• /
• v.7 no.3
• /
• pp.536-542
• /
• 1996

Water-based acrylic sizing agent(GSW-7000) was prepared by emulsion copolymerization for sizing polyester yarns. Ammonium salt version of the acrylic sizing agent offered greater abrasion resistance to weaving forces and water resistance for water jet loom. GSW-7000 exhibited proper viscosity for sizing, high penetration ability and excellent adhesion to polyester yarn. It was possible to reduce the size pick-up to 70~80% of ordinary solvent-based sizing agent due to excellent adhesive strength of GSW-7000.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.816-821
• /
• 2003

This paper deals with a reduction in the setting shrikage of polymer concrete using bentonite as shrinkage reducing agent. This study with polymer concrete using unsaturated polyester(UP) based on recycled PET waste was performed to verify the effect of various shrinkage reducing agent contents and the types of filler which are fly ash and $CaCo_3$. Setting stress induced by setting shrinkage was investigated in temrs of mechanical and chemical combination.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.11 no.4
• /
• pp.133-140
• /
• 2008

The purpose of this study is to provide response methods to minimize the damage from chemical terrorism in a naturally ventilated indoor system using several types of dispersion simulations. Three chemical warfare agents such as sarin(GB), phosgene and chlorine gas which have high potential to be used in terror or to be involved with accidents were selected in this simulation. Fire dynamic simulation based on Large Eddy Simulation which is effective because of less computational effort and detailed expression of the dispersion flow was adopted to describe the dispersion behavior of these agents. When the vent speed is 0.005m/s, the heights of 0.1 agent mass fraction are 0.9m for sarin, 1.0m for phosgene and 1.1m for chlorine gas, and the maximum mass fraction are 0.27 for all three agents. However, when the vent speed is increased to 0.05m/s, the heights of 0.1 agent mass fraction become 1.6m for all three agents and maximum mass fraction inside the room increase to 0.70 for sarin, 0.58 for phosgene and 0.53 for chlorine gas. It is shown that molecular weight of the agents has an important role for dispersion, and it is important to install ventilation system with height less than 1.6m to minimize the damage from chemical toxicity.

• Textile Coloration and Finishing
• /
• v.20 no.6
• /
• pp.26-34
• /
• 2008

Wool fabric having high moisture content were treated with fluorocarbon-based water and oil repellent finishing agents by pad-dry-cure system. Three types of finishing agents which were regular-type or nano-type were adapted to compare the surface chemical composition, water and oil repellent property, crease recovery angle, and durability to repeated laundering. From the surface chemical compositions resulted by ESCA and C1s curve-fitting, it was shown that the regular-type finishing agent were easily taken off from the finished wool fabrics after repeated laundering. On the other hand, the fluoroalkyl groups of nano-type finishing agents turned round from fabric surface to fiber internal after repeated laundering. The water repellency of the wool fabrics treated with regular-type agent had a little changes according to the treatment condition changes and sharply decreased with repeated laundering. However, these values when treated with nano-type agents increased with the concentration and cure temperature and were maintained after 20 times laundering. The wool fabrics treated with nano-type agent had a great oil repellency irrespective of treatment conditions. Furthermore, the wrinkle recovery values of the wool fabrics treated with nano-type agents were higher than those of the fabrics treated with regular-type agent and were unchanged after 20 times laundering.

• Clean Technology
• /
• v.24 no.4
• /
• pp.315-322
• /
• 2018

Industrial use of waste oyster shells is limited because of requiring excessive energy for converting natural oyster shells in the form of calcium carbonate ($CaCO_3$) into calcium oxide (CaO) for this purpose. This study aimed to develop energy-saving process for producing solidifying agent using waste oyster shells for backfill materials. It was suggested that oyster shells were converted to calcium sulfates which were mixed with sodium hydroxide solution and red clay, forming solid specimen. The optimal concentrations of sulfuric acid for sulfation of oyster shell and sodium hydroxide to generate calcium hydroxide ($Ca(OH)_2$), were determined. Unconfined compressive strength of solid specimen increased with increasing the content of solidifying agent while it increased also with increasing ratio of natural oyster shells to coal ash. The result clearly demonstrates that solidifying agent consisting of sulfuric acid-treated oyster shell, coal ash, and sodium hydroxide solution, can be effectively utilized for preparing backfill materials using natural oyster shell and coal ash. Sulfuric acid-treated oyster shell-based solidifying agent has not been previously developed and will contribute to broaden industrial application of waste oyster shells.

• Applied Chemistry for Engineering
• /
• v.10 no.5
• /
• pp.639-643
• /
• 1999

Interpenetrating polymer networks(IPNs) composed of castor oil(CO) polyurethane(PU) and epoxy resin were prepared by the simultaneous polymerization technique. Two types of PU were prepared using 1,4-butanediol(BD) and BD/trimethylolpropane(TMP) as a chain extending agent and crosslinking agent. The PU/epoxy based on BD as a chain extending agent showed more shift in the damping peak than PU/epoxy based on BD/TMP as the PU content was increased. BDPU/epoxy simultaneous interpenetrating polymer networks(SINs) had a better compatibility than BD/TMP-PU/epoxy SINs. For both systems, it was postulated that unique network formation of PU/epoxy SINs as a chain extending agent and crosslinking agent had occurred to a significant extent of phase mixing. The types of chain extender in the PU were found to be an important factor in determining the phase mixing of the IPNs. When the BD/TMP-PU reaction was faster than epoxy network, the extent of phase mixing was retarded by decreasing entanglement of networks. It was found that both PU/epoxy SINs provided enhanced flexural properties and fracture toughness, fracture surfaces of BDPU/epoxy and BD/TMP-PU/epoxy SINs showed the localized shear deformation and generation of stress whitening associated with the cavitation.