• Journal of the Korean Society of Food Science and Nutrition
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• v.18 no.4
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• pp.410-422
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• 1989

Soybean protein isolates were acylated with succinic anhydride and partially hydrolyzed with trypsin. Chemical modification decreased protein contents of samples and, in amino acid composition, tyrosine was increased comparatively. And lysine was increased remarkably by partial proteolysis. Succinylation and trypsin treatment increased the aqueous solubility and shifted the isoelectric potint that showed high pH-dependence of protein solubility. Protein solubility was influenced by salt concentration such as $NaCl,\;CaCl_2,\;NaNO_3$ and $NaH_2PO_4$. Chemical modification increased the absorption of oil and water, emulsification properties and foam capacity, but decreased foam stability, ultraviolet absorbance and bulk density. Protein-protein Interaction between soybean protein isolates and beef protein increased the emulsifying activity, emulsifying activity index and foaming properties, but it didn't have any influence on emulsion stability.

• Journal of the Korean Chemical Society
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• v.59 no.5
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• pp.413-422
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• 2015

Proton exchange membrane (PEM), which transfers proton from the anode to the cathode, is the key component of the proton exchange membrane fuel cell (PEMFC). Nafion is widely used as PEM due to its high proton conductivity as well as excellent chemical and physical stabilities. However, its high cost and the environmental hazards limit the commercial application in PEMFCs. To overcome these disadvantages, various alternative polymer electrolytes have been investigated for fuel cell applications. We used densely sulfonated polymers to maximize the ion conductivity of the corresponding membrane. To overcome high swelling, dipole-dipole interaction was used by introducing nitrile groups into the polymer backbone. As a result, physically-crosslinked membranes showed improved swelling ratio despite of high water uptake. All the membranes with different hydrophilic-hydrophobic compositions showed higher conductivity, despite their lower IEC, than that of Nafion-117.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.263-267
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• 2011

This paper presents a numerical investigation of the deflagration to detonation transition (DDT) of flame acceleration by a shock wave filled with an ethylene-air mixture in bent tube. A model consisting of the reactive compressible Navier-Stokes equations and the ghost fluid method (GFM) for complex boundary treatment is used. A various intensities of incident shock wave simulations show the generation of hot spots by shock-flame interaction and the accelerated flame propagation due to geometrical effect. Also the first detonation occurs nearly constant chemical heat release rate, 20 MJ/($g{\cdot}s$). Through our simulation's results, we concentrate the complex confinement effects in generating strong shock wave, shock-flame interaction, hot spot and DDT in pipe.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.311-316
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• 1998

The adsorption equilibrium properties of bovine serum albumin(BSA-protein) for three kinds of porous microgels with different physical and chemical features were investigated. The adsorption amount of BSA-protein on poly(butyl methacrylate)(PBMA) microgels was higher than those on poly(vinyl pyridine)(PVP) and poly(acrylonitrile) (PAN) microgels due to the hydrophobic interaction between polymer and protein in an aqueous solution. And PBMA microgels had more irreversible adsorption equilibrium properties the PVP and PAN microgels. It implies that hydrophobic interaction plays a more important role in adsorption properties of BAS-protein than physical properties of polymer and electrostatic attraction between protein and polymer microgels. Characteristics of the microgels used in this study followed Langmuir equation better than the Freundlich equation.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.4
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• pp.284-288
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• 2009

With explosively growing PPI databases, the computational approach for a prediction and configuration of PPI network has been a big stream in the bioinformatics area. Recent researches gradually consider physicochemical properties of proteins and support high resolution results with integration of experimental results. With regard to current research trend, it is very close future to complete a PPI network configuration of each organism. However, direct applying the PPI network to real field is complicated problem because PPI network is only a set of co-expressive proteins or gene products, and its network link means simple physical binding rather than in-depth knowledge of biological process. In this paper, we suggest a protein functional flow model which is a directed network based on a protein functions' relation of signaling transduction pathway. The vertex of the suggested model is a molecular function annotated by gene ontology, and the relations among the vertex are considered as edges. Thus, it is easy to trace a specific function's transition, and it can be a constraint to extract a meaningful sub-path from whole PPI network. To evaluate the model, 11 functional flow models of Homo sapiens were built from KEGG, and Cronbach's alpha values were measured (alpha=0.67). Among 1023 functional flows, 765 functional flows showed 0.6 or higher alpha values.

• Journal of the Korean Chemical Society
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• v.44 no.4
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• pp.356-362
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• 2000

Students' protocols obtained from audio/video taping of small cooperative group problem solving processes were analyzed in the aspectsof verbal behaviors. The frequencies of the behaviors were com-pared by students' previous achievement level. Students' involvement in the verbal interaction for each level of students in each small group were also investigated. High-ability students ebility students and medium-or low-ability students.No significant differences were found in the subcategories of 'receiving information' or 'asking'. 0nly 3 small groups among 12 groups studied were found tobe bal-anced in students' involvelment. lnvolvement of medium-ability studentstended to be lower than that of high-and low-abilit students.

• Journal of the Korean Chemical Society
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• v.32 no.2
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• pp.113-121
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• 1988

The retention mechanism and separation of various aromatic sulfonic and carboxylic acids on reversed-phase liquid chromatographic column were studied in the mobile phase containing dodecyltrimethylammonium bromide (DTAB). The retention mechanism was found to be followed the ion-interaction model where the DTAB occupies a primary layer at the stationary phase while the sample anions and other co-anions in the system compete for forming the secondary layer. The capacity factors of samples were influenced by the several factors such as pH, concentration of various organic solvents, co-anions in the mobile phase and functional groups in sample molecules. Some mixtures of organic samples were attempted to separate under optimum condition.

• Journal of the Korean Chemical Society
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• v.27 no.5
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• pp.330-339
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• 1983

The CNDO/2 and STO-3G calculations were performed on nitrogen, oxygen, and sulfur compounds in order to examine the effect of interactions between two nonbonding (n) orbitals in the same molecule separated by N intervening $\sigma$ bonds based on the PMO approach. Calculated basis level energies, energy splittings, and interaction energy changes for both chain and cyclic model compounds were qualitatively compared with the corresponding predictions derived from perturbational formalism for n-n orbital interactions and successfully explained in terms of the derived energy expressions. In general, through-space interaction term could be neglected in the N and O systems. And the calculated results were explained simply by through-bond interaction term. As a result, through-bond interaction placed n- below n+ for odd systems and n+ below n- for even systems. Also energy splittings in odd systems were larger than those in even systems. However, in the cases of cis-ethylene diamine and o-phenylene diamine(conformer VI in Table 4), through-space interaction term was found to be substantial and the opposing effects of through-space and through-bonds interactions were observed. Finally it was found that the interactions between two n orbitals on S atoms always had some contribution of the destabilizing through-space interaction term. This result was consistent with the fact that the lone pair lobes of third elements were larger in size than those of the second period elements.

• Korean Chemical Engineering Research
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• v.45 no.2
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• pp.143-148
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• 2007

In hydrogen production for fuel cell by reforming city-gas, sulfur compounds, odorant in city-gas, are detrimental to reforming catalyst and fuel cell electrodes. We prepared metal salt impregnated ${\beta}-zeolite(BEA)$ to remove sulfur compound in city-gas by adsorption. The sulfur breakthrough adsorption capacity was changed depending on the concentration and species of metal salt. $AgNO_3$ impregnated BEA showed the highest sulfur breakthrough capacity among adsorbents used in this experiment(41.1 mg/g). But metal salt impregnated BEA such as $Ni(NO_3)_2/BEA$, $Fe(NO_3_)_3/BEA$, $Co(NO_3)_2/BEA$ showed a certain amount of sulfur adsorption capacity comparable to $AgNO_3/BEA$. Adsorption temperature effect, desorption study, and x-ray photoelectron spectroscopy analysis revealed that the dominant interaction between metal impregnated adsorbent and sulfur compounds was not chemisorption but physisorption.

• Applied Biological Chemistry
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• v.48 no.3
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• pp.189-200
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• 2005

Biological nitrogen fixation is an important process for academic and industrial aspects. This review will briefly compare industrial and biological nitrogen fixation and cover the characteristics of biological nitrogen fixation studied in Azotobacter vinelandii. Various organisms can carry out biological nitrogen fixation and recently the researches on the reaction mechanism were concentrated on the free-living microorganism, A. vinelandii. Nitrogen fixation, which transforms atmospheric $N_2$ into ammonia, is chemically a reduction reaction requiring electron donation. Nitrogenase, the biological nitrgen fixer, accepts electrons from biological electron donors, and transfers them to the active site, FeMo-cofactor, through $Fe_4S_4$ cluster in Fe protein and P-cluster in MoFe protein. The electron transport and the proton transport are very important processes in the nitrogenase catalysis to understand its reaction mechanism, and the interactions between FeMo-cofactor and nitrogen molecule are at the center of biological nitrogen fixation mechanism. Spectroscopic studies including protein X-ray crystallography, EPR and $M{\ddot{o}}ssbauer$, biochemical approaches including substrate and inhibitor interactions as well as site-directed mutation study, and chemical approach to synthesize the FeMo-cofactor model compounds were used for biological nitrogen fixation study. Recent research results from these area were presented, and finally, a new nitrogenase reaction mechanism will be proposed based on the various research results.