• Macromolecular Research
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• v.17 no.10
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• pp.739-745
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• 2009

N,N'-(bicyclo[2,2,2]oct-7-ene-tetracarboxylic)-bis-L-amino acids 3a-g were synthesized by the condensation reaction of bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride 1 with two equimolars of Lalanine 2a, L-valine 2b, L-leucine 2c, L-isoleucine 2d, L-phenyl alanine 2e, L-2-aminobutyric acid 2f and L-histidine 2g in an acetic acid solution. Seven new poly(amide-imide)s PAIs 5a-g were synthesized through the direct polycondensation reaction of seven chiral N,N'-(bicyclo[2,2,2]oct-7-ene-tetracarboxylic)-bis-L-amino acids 3a-g with bis(3-amino phenyl) phenyl phosphine oxide 4 by two different methods: direct polycondensation in a medium consisting of N-methyl-2-pyrrolidone (NMP)/triphenyl phosphite (TPP)/calcium chloride ($CaCl_2$/pyridine (py), and direct polycondensation in a tosyl chloride (TsCl)/pyridine (py)/N,N-dimethylformamide (DMF) system. The polymerization reaction produced a series of flame-retardant and thermally stable poly(amide-imide)s 5a-g with high yield. The resulted polymers were fully characterized by FTIR, $^1H$ NMR spectroscopy, elemental analyses, inherent viscosity, specific rotation and solubility tests. Data obtained by thermal analysis (TGA and DTG) revealed that the good thermal stability of these polymers. These polymers can be potentially utilized in flame retardant thermoplastic materials.

• Clean Technology
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• v.7 no.4
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• pp.281-290
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• 2001

A microwave-assisted process to prepare chitosan from natural crabshells has been investigated. This study was primarily to examine the effectiveness of microwave as clean energy for chitosan preparation. Several human-edible organic acids were used as clean catalyst, possibly to improve the current HCl-based hydrolysis process of polymeric chitosan. The microwave was found to be effective substantially in reducing the reaction time. Nonetheless, no beneficial effect of microwave other than time, such as the chemical selectivity, was hardly observed. The organic acids were very effective in the hydrolysis reaction of polymeric chitosan. Their catalytic behavior was greatly improved especially when reactions were performed under pressure. In the case of autoclave reaction for 60 minutes at $120^{\circ}C$, viscous solution of polymeric chitosan (mol. wt. > 300,000) turned into thin solutions of water-like viscosity, which means chitosan molecules were decomposed to very small-sized oligomers.

• Journal of the Korea Computer Graphics Society
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• v.19 no.3
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• pp.1-11
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• 2013

Fluid Implicit Particle (FLIP) method is used in Visual Effect(VFX) industries frequently because FLIP based simulation show high performance with good visual quality. However in large-scale fluid simulations, the efficiency of FLIP method is low because it requires many particles to represent large volume of water. In this papers, we propose a novel hybrid method of simulating fluids to supplement this drawback. To improve the performance of the FLIP method by reducing the number of particles, particles are deployed inside thin layers of the inner surface of water volume only. The coupling between less-disspative solutions of FLIP method and viscosity solution of level set method is achieved by introducing a new surface reconstruction method motivated by surface reconstruction method[1] and moving least squares(MLS) method[2]. Our hybrid method can generate high quality of water simulations efficiently with various multiscale features.

• Clean Technology
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• v.7 no.1
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• pp.65-74
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• 2001

Modified dip-coating method 8.3 times shorten in solution volume-coated and 83.3 times in coating time than existing dip-coating method. Coating weight increased nearly 2~3 times. So modified dip-coating method is evaluated that it is economic and has a efficiency. When we make an experiment in coated $LaCoO_3$ on ceramic monolith in modified dip-coating method which use 2 coating applications with relative viscosity $0.006202kg{\cdot}m/sec$, it showed a superior reaction at 88.56mg per ceramic unit gram in NO-CO reaction(optimum coating amount). When we make an experiment in the same size of ceramic filter cell with different conditions 100, 200cell per square inch, the result in low temperature($200^{\circ}C{\sim}350^{\circ}C$), 200cell3 per square inch is 6~23% higher in NO reduction and 11% in CO oxidation than 100cell per square inch. It is because the more the number of cells in the ceramic filter increase, the more catalytic surface area is expanded.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.701-705
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• 2014

Water extracts of root, leaf, branch and fruit of Cudrania tricuspidata were tested to use as natural antiwrinkle and whitening cosmetic ingredient. Root extract indicated 86.5 mg/g polyphenol concentration and 55.5 mg/g flavonoid concentration. From MTT test, root, branch and fruit extract did not show cell toxicity up to $1,000{\mu}g/mL$, however, leaf extract displayed significant cell toxicity in concentrations higher than $200{\mu}g/mL$. Cudrania tricuspidata root extracts displayed excellent 81% tyrosinase inhibition (whitening effect), 58% elastase inhibition (antiwrinkle effect) at $500{\mu}g/mL$ and showed minor UVB absorbance. When solution and lotion formulation were made including Cudrania tricuspidata root extract, they are stable at $25^{\circ}C$ for 21 days, but showed significant deviation in viscosity and particle size at $47^{\circ}C$. From the study, Cudrania tricuspidata root extract demonstrated good potential for natural whitening and antiwrinkle cosmetic agent.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.138-142
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• 1999

Imide-containing diamine and dicarboxylic acid monomers, N-(4-aminophenyl)-4-aminophthalimide(APAP), N-(4-carboxyphenyl)-4-carboxyphthalimide(CPCP), N,N'-oxydiphenylenebis(4-aminophthalimide)(ODPAP) and N,N'-oxydiphenylenebis(4-carboxyphthalimide)(ODPCP) were prepared. Poly(amide-imide)s were prepared by condensation reaction of the diamine and the dicarboxylic acid monomers. Poly(amide-imide)s were also prepared from the diamine monomers and aromatic acid chlorodes such as terephthaloyl chloride and isophthaloyl chloride. The polymers possess inherent viscosity of 0.18~0.67 dL/g and brittle films were cast from NMP/LiCl solution. The poly(amide-imide)s are easily soluble in NMP/LiCl and also partially soluble in polar aprotic solvents such as DMF, DMSO, NMP and DMAc even at $80^{\circ}C$. DSC traces of polymers showed no glass transition temperature and melting temperature, and TGA traces showed a 10% weight loss at $500^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.26 no.1
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• pp.51-56
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• 1994

Development for extraction method of sea tangle was investigated with addition of sucrose, NaCl, EDTA-2Na, SHMP, and hydrolysis with commercial polysaccharide hydrolyzing enzymes. The total solids and protein yields were significantly increased by enzymatic hydrolysis or addition of NaCl and EDTA-2Na during boiling. The extract prepared by enzymatic hydrolysis followed by 2 hrs of boiling in 1.5% NaCl solution was significantly improved in solids and protein yield from 24.1% and 13.9% of 2 hrs of water boiling to 44.6% and 32.2%, respectively. The combined method increased the amino-nitrogen content but reduced the turbidity and viscosity. Extracts with a high intensity of total and seaweed-like taste as revealed by sensory evalution were obtained by combined method.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.3
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• pp.173-184
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• 2005

A capillary action-induced tension develops in the tear layer between the contact lens and cornea, which leads to the restoring force due to difference in the layer thickness between either upper and lower or left and right side of the lens when it is displaced off the equilibrium position as a result of blinking. Suppose the lens was displaced a certain distance from the equilibrium position, lens starts to oscillate toward the equilibrium position with the decreasing amplitude due to the restoring force as well as the velocity dependent viscous damping force in the tear layer. A mathematical model which consists of the differential equations and their numerical solution was proposed to analyze the damped oscillations of lenses. The model predicts the time dependence of lenses after the blink varying the various parameters such as Be, diameters, masses and positions displaced from equilibrium. As the Be and mass of lens increases the rate of amplitude reduction decreases, which requires a more time for the lens to return to the equilibrium position. It seems that varying the lens' displacement and diameters affect the lens' motion very little.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1232_1233
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• 2009

Paraquat is well-known to cause hepatotoxic responses in human and other mammal species. In solution, it forms free radicals and charge-transfer complex of which formation plays an important role in determination of its biological activity in the presence of various anions. The HepG2 cells were cultured onto a quartz crystal sensor which is possible to detect the density and a viscosity changes using the resonance frequency (F) and the resonance resistance (R). The plot of F-R diagram is able to explain the rheological change of cells onto the surface of the quartz crystal sensor. In this paper, we investigated the physical properties of the HepG2 cells cultured onto a ITO electrode of the quartz crystal sensor according to the paraquat injection at various concentrations (100 mM, 10 mM, 1 mM). We also observed the morphological changes with a micro CCD camera, simultaneously. The HepG2 cells were cultured onto the ITO electrode surface of the quartz crystal modified a collagen film in $CO_2$ incubator. After the paraquat injection, we observed the changes of the morphologies by the micro CCD camera depending on time and analyzed the physical changes of cells on the electrode surface of quartz crystal using F-R diagram. From all results, we proved the effect of paraquat at various concentrations which is led to an apoptosis such as weakening and death of the cells by oxidation and reduction reaction that were produced the superoxide anions and other free radicals.

• Journal of Microbiology and Biotechnology
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• v.8 no.6
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• pp.618-624
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• 1998

The culture conditions for Bacillus sp. DP-152 in the flask were investigated for the production of polysaccharide locculant, DP-152. The optimum pH and temperature for the locculant production were 8.0 and $30^{\circ}C$, respectively. The avorable substrates for flocculant production were soluble tarch and ammonium nitrate. The medium composition was optimized as follows: 30 g soluble starch, 0.75 g $NH_4NO_3,\; 2.0g\; K_2\;HPO_4,\; 0.1\; g KH_2PO_4,\; 0.2g\; MgSO_4.\; 7H_2O,\; and\; 0.2g\; MnSO_4~5H_2O$ in 11 of distilled water. Under this optimized condition, flocculating activity has been improved 4-fold compared with that of the basal medium. In the culture flask, the highest flocculating activity was obtained after 70 h of cultivation and the amount of bioflocculant DP-152 yielded was 12.4 g/$\ell$. The solution of bioflocculant DP-152 showed non-Newtonian characteristics. Bioflocculant DP-152 exhibited apparently higher viscosity at all concentrations compared to that of zooglan (from Zoogloea ramigera), and it was stable over a wide range of temperatures and pHs.