• Analytical Science and Technology
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• v.5 no.1
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• pp.121-126
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• 1992

Transmission electron microscopy was used to investigate the structure of GaAs ${\Sigma}=19$, [110] tilt grain boundaries. Relative positions of Ga and As atoms in each grain on either side of the boundaries were determined by examining the dynamical coupling between HOLZ reflections and(200) beams. No inversion symmetry was present across the boundaries. These boundaries were observed to have a strong tendency to lie parallel to {331} planes. The atomic structure and lattice translation at these boundaries was studied in detail by high-resolution transmission electron microscopy(HRTEM). The boundary consists of units of 5-, 7-, and two 6-member rings.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.339-339
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• 2006

In this study, the microvoids in glassy polymers were investigated by Xe sorption and $^{129}Xe$ NMR measurements. Xe sorption isotherms of glassy polymers have been successfully interpreted by the dual-mode sorption model. $^{129}Xe$ NMR chemical shift of the $^{129}Xe$ in the samples show nonlinear low-field shift with increasing sorption amount of Xe because of a fast exchange of Xe atoms between Henry and Langmuir sites, whereas it has showed linear shift against sorption amount of Xe into the Langmuir site. From this Xe-density dependence of the $^{129}Xe$ NMR chemical shift, it has been able to estimate mean size of the microvoids in glassy polymer. It is confirmed that there is correlation between ${C_H}'$ and volume or number of microvoids. From these findings, it is demonstrated that $^{129}Xe$ NMR spectroscopy is a powerful technique to determine the mean size and number of microvoids in glassy polymers.

• Proceedings of the Korean Vacuum Society Conference
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• 1994.02a
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• pp.35-35
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• 1994

The surface segragation of NiZr, CuZr alloy has been studied wi th X-ray Imotoelectron spectroscopy(XPS), Auger electron spectroscopy(AES) and low energy ion scattering(LEIS). The composition of outmost atomic layer has been determinded by the use of LEIS at several incident energies using Ar+ ion. In the LEIS analysis, the effect of charge exchange has been estimated by a novel measurment of the charge exchange parameters while simul taneous determining the relative concentrations of Ni and Zr and the complementary information obtained will be described. The composition of the clean annealed surface, measured with AES only, will be contrasted wi th the surface concentration of the preferentially sputtered surface. The experimental results has been clearly demonstrated that when the NiZr ruld CuZr alloys are exposed to continuous Ar+ ion bombardment the outermost atomic layer is Zr rich due to preferential sputtering of Ni atoms. where Ni is preferentially sputtered, but the difference in sputtering yields is not sufficient to explain the observed composition. Therefore, it is necessary to consider other processes such as Radiation Induced Segregation(RIS). The surface composition of the heated sample surface predicts that Zr should surface segregate which futher supports the view that part of the Zr enrichment is due to RIS.to RIS.

• Bulletin of the Korean Chemical Society
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• v.26 no.4
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• pp.594-598
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• 2005

Treatment of a solution of $CuCl_2$ in dimethyl phosphate (DMP) with DMSO under nitrogen atmosphere afforded to a light blue fluorescence powder. Slow evaporation of $H_2O$-DMSO solution of this powder resulted in blue-sky crystals of a new polymeric Cu(II) complex, with a unit cell composed of $Cu_2(DMP)_4$(DMSO), (1). The crystal and molecular structure of the complex acquired crystallographically. Compound (1) crystallizes in the monoclinic space group $P2_1$/n with a = 12.8920(11) $\AA$, b = 13.1966(11) $\AA$, c = 14.7926(13) $\AA$, $\alpha$ = 90$^{\circ}$, $\beta$ = 98.943(2)$^{\circ}$, $\gamma$ = 90$^{\circ}$, V= 2486.1(4) ${\AA}^3$, and Z = 4. A square pyramidal environment for the metal center was established by coordination of oxygen atoms of four bridging DMP ligands in the basal positions and binding a tri-centered oxygen atom of DMSO in the apical disposition of Cu(II). The sixth position was also affected by a weak interaction with the sulfur atom of another DMSO. The phosphorous atom in the bridging DMP was arranged in a deformed tetrahedron with (gg) conformation for methyl esters with $C_{2v}$ symmetry.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2271-2278
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• 2007

Electron transfer of a redox protein at a bare gold electrode is too slow to observe the redox peaks. A novel Nafion-riboflavin functional membrane was constructed during this study and electron transfer of cytochrome c, superoxide dismutase, and hemoglobin were carried out on the functional membrane-modified gold electrode with good stability and repeatability. The immobilized protein-modified electrodes showed quasireversible electrochemical redox behaviors with formal potentials of 0.150, 0.175, and 0.202 V versus Ag/AgCl for the cytochrome c, superoxide dismutase and hemoglobin, respectively. Whole experiment was carried out in the 50 mM MOPS buffer solution with pH 6.0 at 25 oC. For the immobilized protein, the cathodic transfer coefficients were 0.67, 0.68 and 0.67 and electron transfer-rate constants were evaluated to be 2.25, 2.23 and 2.5 s?1, respectively. Hydrogen peroxide concentration was measured by the peroxidase activity of hemoglobin and our experiment revealed that the enzyme was fully functional while immobilized on the Nafion-riboflavin membrane.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.417-420
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• 2006

The composition and structure of dendrite phase within $Zr_{76.11}Ti_{4.20}Cu_{4.51}Ni_{3.16}Be_{1.49}Nb_{10.53}$ bulk metallic glass (BMG) were confirmed by using an EPMA, XRD and TEM, respectively. The chief elements of dendrite phase were Zr-Ti-Nb and had a BCC structure. The thermal properties of this BMG have been then subsequently investigated by using a differential scanning calorimeter (DSC). The glass transition and crystallization onset temperatures were determined as $339.7^{\circ}C$ and $375.8^{\circ}C$ for this alloy, respectively. Mechanical properties have also been examined by conducting a series of uniaxial compression tests at various temperatures within supercooled liquid region under the strain rates between $10^{-4}/s$ and $3{\times}10^{-2}/s$. The deformation behavior of BMG composite within supercooled liquid region is similar to one of Vit-1 exhibiting amorphous single phase alloy. The flow stresses of BMG composite, however, are entirely higher than those of Vit-1 because dendrite phases are interfere with moving of atoms.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.659-663
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• 2011

The photodissociation dynamics of bromobenzene near 234 nm has been investigated using a two-dimensional photofragment ion-imaging technique coupled with a state-selective [2+1] resonance-enhanced multiphoton ionization (REMPI) scheme. The nascent Br atoms are produced by the primary C-Br bond dissociation, which leads to the formation of $C_6H_5$ ($\tilde{X}$) and Br($^2P_j$, j = 1/2, 3/2). The observed translational energy distributions have been fitted by a single Boltzmann function and two Gaussian functions. Trimodal translational energy distributions of Br($^2P_j$) have been assigned to the direct/indirect dissociation mechanisms originating from the initially excited $^3({\pi},{\pi}^*)$ state. The assignments have been confirmed by the recoil anisotropy and distribution width corresponding to the individual components.

• Journal of the Korean Chemical Society
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• v.56 no.4
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• pp.406-415
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• 2012

The corrosion inhibition of copper-nickel alloy by Ethylenediamine (EDA) and Diethylenetriamine (DETA) in 1.5M HCl has been investigated by weight loss technique at different temperatures. Maximum value of inhibitor efficiency was 75% at $35^{\circ}C$ and 0.2 M inhibitor concentration EDA, while the lower value was 4% at $35^{\circ}C$ and 0.01 M inhibitor concentration DETA. Two mathematical models were used to represent the corrosion rate data, second order polynomial model and exponential model respectively. Nonlinear regression analysis showed that the first model was better than the second model with high correlation coefficient. The reactivity of studied inhibitors was analyzed through theoretical calculations based on density functional theory (DFT). The results showed that the reactive sites were located on the nitrogen (N1, N2 and N4) atoms.

• Journal of the Korean Magnetics Society
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• v.8 no.1
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• pp.1-5
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• 1998

Acicular Fe-Co alloy particles are one of the candidates for high-density magnetic recording media. We examined the effects of Co additions on the magnetic properties of Fe-Co alloy particles by using M$\'{o}$ssbauer spectroscopy, TEM, and X-ray diffraction. Acicular $Fe_n$Co (n=5, 4, 3, 2) alloy particles coated with silica, were prepared by a chemical coprecipitation method and subsequent H $_2$ reduction. The crystal structure was found to be cubic in all n ranges. The lattice constant $a_0$ decreases with increasing Co contents. Analysis of $^{57}Fe$ M\'{o}$ssbauer effect data in terms of the local configurations of Co atoms has permitted the influence of magnetic hyperfine interactions to be monitored.

• Journal of Integrative Natural Science
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• v.8 no.2
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• pp.89-98
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• 2015

Chemoattractant receptor homologous molecule expressed on Th2 cells (CRTh2) is a G-protein coupled receptor targeted for inflammatory diseases such as asthma, allergic rhinitis and atopic dermatitis. In this study, pharmacophore modeling and comparative molecular field analysis (CoMFA) were performed on the series of 2-(2-(benzylthio)-1H-benzo[d]imidazol-1-yl) acetic acids derivatives. Five highly active compounds were used for generation of pharmacophore models using GASP module. The best pharmacophore model was selected and used as template for the alignment of compounds which was used for CoMFA analysis. The best predictions obtained for CoMFA was $q^2=0.545$, $r^2=0.756$. The predictive ability of the model was investigated using 15 test set compounds. Contour maps suggested that presence of bulky substituents at $5^{th}$ position of benzene ring connected to suphur atoms attached to imidazol ring will increase the activity of the compounds. The results obtained from this study will be useful to design more potent CRTh2 antagonists.