• Polymer(Korea)
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• v.32 no.2
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• pp.189-192
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• 2008

A styrylpyrylium salt (DHSP) was synthesized and then photodimerized to obtain a cyclobutane-type dimer (DHSP dimer). Methacryloyl group was incorporated into DHSP dimer to obtain DMSP dimer. Based on FT-IR analysis of a crosslinked DMSP dimer, it was considered that the cyclobutane structure reversed to styryl C=C bonds upon crack formation. Fluorescence measurement of DHSP in solid state (excitation at 385 nm) showed emission centered at 626 nm, while DHSP dimer revealed very weak emission. Fluorescent emission from microcracks in a film of crosslinked DMSP dimer was observed upon exposure to $330{\sim}385\;nm$ light.

• Journal of Integrative Natural Science
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• v.9 no.2
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• pp.103-112
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• 2016

The crystal structure of the potential active Methyl 8-bromo-3-phenyl-5a,9a-dihydro-3H-chromen [4,3-c][1,2] isoxazole-3a(4H)-carboxylate ($C_{18}H_{15}BrNO_4$) has been determined from single crystal X-ray diffraction technique. The title compound crystallizes in the triclinic space group Pī with unit cell dimension a=8.3129 (3) ${\AA}$, b=9.5847 (4) ${\AA}$ and c=11.1463(4) ${\AA}$ [${\alpha}=98.457(3)^{\circ}$, ${\beta}=102.806(2)^{\circ}$ and ${\gamma}=105.033(5)^{\circ}$]. Single crystals suitable for X-ray diffraction were obtained by slow evaporation method, the isoxazole and six membered pyran rings adopts envelope conformation. In the crystal, molecules are linked via pairs of inter molecular $C-H{\ldots}O$ hydrogen bonds to form dimmers.

• Korean Journal of Human Ecology
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• v.15 no.6
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• pp.973-984
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• 2006

This study examined the asset allocation of the aged and analyzed the impact variables on the portfolio ratio of different kind of finanical assets. The aged was divided three groups, 55-65, 65-75 and 75 over. The results showed that the aged are not likely to invest on risky asset and their assets composed of mostly real estates and bank account. The study include four different assets, such as liquid asset, risky assets, horne equity and other real estates, which reflects the liquidity problems of households asset allocation for the aged in Korea. The aged who do not participate on stock market are likely to have more liquid assets. Households lived in Daegu, Kwangju, ChungCheong and CheonRa tend to have more liquid assets compared to those in Seoul. Total income is appeared having positive relationship with illiquid assets including stock, bonds, and private pension. Age group with 75yrs over tend to have greater mean of illiquid assets and it may caused by the polarization of assets, which gives intuition for the future study.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.388.1-388.1
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• 2014

The performance of PVA(polyvinyl alchol) is better than another organic dielectric material. Therefore, PVA has been researched for organic and in-organic dielectric material. But research of changing PVA's dielectric constant and leakage current by increasing temperature and concentration was insigificant. We try to find pure PVA and cross-linked PVA's characteristic of dielectric by changing temperature and concentration. 5/10/15wt% PVA concentration (5% interval) was in progress, PVA at $100/150/200/250^{\circ}C$ ($50^{\circ}C$ interval) of experiments was conducted in relation to temperature. The higher the concentration, leakage currents decrease, and dielectric constant is increased. With regard to temperature, we could not see a big change of leakage current and dielectric constant of pure PVA until $200^{\circ}C$. However, we could see a tendency to increase significantly at $250^{\circ}C$. Also, leakage current and dielectric constant of cross-linked PVA gradually increased from at $100^{\circ}C$ to $200^{\circ}C$ and then sharply increased from at $250^{\circ}C$. We tried to find that PVA's inner bonds(hydroxyl group (OH-) lead to the results.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.374-378
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• 2013

Two novel binuclear metal-organic coordination complexes [$Cd_2(Hdpa)_4(bpy)_2$] (1), [$Dy_2(dpa)_2(bpy)_2(NO_3)_2-(H_2O)_2$](bpy) (2) (where $H_2dpa$ = biphenyl-2,2'-dicarboxylic acid, bpy = 2,2'-bipyridine) have been synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction, spectral method (IR), elemental analysis (EA), powder X-ray diffraction (XRD), electronic spectra (UV-vis), fluorescent in the solid state and thermogravimetric analysis (TGA). Complexes 1-2 crystallizes isomorphously in the Triclinic space group P-1. The ${\pi}-{\pi}$ stacking interactions and hydrogen-bonds play a vital role in determining the crystal packing and construction of the extended 3-D supramolecular network.

• Textile Coloration and Finishing
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• v.7 no.4
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• pp.8-15
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• 1995

A series of thermotropic Polyurethanes mesogenic unit were synthesized by polyaddition of a para-type diisocyanate such as 2,5-tolylene diisocyanate(2,5-TDI) with 4-4'-bis($\omega$-hydroxyalkoxy) biphenls(BPm: $HOCmH_{2m}OC_{6}H_{4}OC_{m}H_{2m}OH$ : m is the carbon number of the hydroxyalkoxy group) in DMF. Intrinsic viscosities of the polymers were in the range of 0.41~0.99dL/g DSC thermograms for these polymers exhibited two endothermic peaks corresponding to phase transitions of melting and isotropization. For examplem polyurethane 2,5-TDI/BPll with [η]=0.99 prepared from 2.5-TDI and 4,4'-bis[11-hydroxyundecaoxy biphenyl(BP11) a liquid crystalline phase from 156 to 173$^{\circ}C$. The thermotropic properites of liquid crystalline polyurethanes have been investigated by wide-angle X-ray scatter(WAXS), infrared (IR) spectroscopy, and differential scanning calorimetry (DSC). The mesomorphic behavior of the polyurethanes was concluded to be greatly dependent on the intermolecular hydrogen bonds through the urethane.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.75-75
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• 2003

We report here the results on N-acetyl-N'-dimethylamide of proline (Ac-Pro-NM $e_2$) calculated using the ab initio molecular orbital method with the self-consistent reaction field (SCRF) theory at the HF level with the 6-31+G(d) basis set to investigate the conformational preference of polyproline depending on the cis/trans peptide bonds and down/up puckerings along the backbone torsion angle $\square$ in the gas phase, chloroform, and water. In the gas phase, Ac-Pro-NM $e_2$ has seven local minima of tFd, tFu, cFd, cFu, cAu, tAu, and cAd conformations. In particular, polyproline conformations tFd, tFu, cFd, and cFu are found to be more stable than $\square$-helical conformations cAu, tAu, and cAd. In contrast, Ac-Pro-NHMe has seven local minima of tCd, tCu, cBd, cAu, tAu, cFd, and cFu conformations. Conformations tCd and tCu are found to be most stable, which is ascribed to the intramolecular hydrogen bond between C=O of acetyl group and $N^{~}$ H of N'-methyl amide group. The stability of the cFd conformation (i.e., the polyproline I structure) in chloroform is somewhat increased, relative to that in water, although tFd and tFu conformations (i.e., the polyproline II structure) are dominate both in chloroform and water. The population of backbone conformations feasible in chloroform and water is consistent with the experiments. This work is supported by a Korea Research Foundation Grant (KRF-2002-041-C00129).

• Korea Journal of Cosmetic Science
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• v.2 no.1
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• pp.11-19
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• 2020

The aim of this study is to investigate the effect of various pentapeptides on hair repair depending on the characteristics of comprising amino acids using crosslinking agents in hair. Total ten peptides were synthesized with two kinds of amino acids respectively, of which were previously categorized according to R group of the amino acids contributing to the characteristic of each peptide: STTSS (Ser-Thr-Thr-Ser-Ser), LIILL (Leu-Ile-Ile-Leu-Leu), CMMCC (Cys-Met-Met-Cys-Cys), DEEDD (Asp-Glu-Glu-Asp-Asp), RKKRR (Arg-Lys-Lys-Arg-Arg), TAMRA-STTSS, TAMRA-LIILL, TAMRA-CMMCC, TAMRA-DEEDD, and TAMRA-RKKRR. Pentapeptide alone, or pentapeptides with crosslinking agents such as polymeric carbodiimide (PCI) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) were treated to chemically damaged hair. Hair diameter and break strength (N = 40/case) were measured to calculate tensile strength of hair for computing hair repair ratio, and fluorescence yields (N = 20/case) were collected for hair treated with TAMRA-peptides. The tensile strength of hair treated with pentapeptides alone, or pentapeptides with cross-linking agents is consistent with the fluorescence yield from the microscope images of the cross-sectioned hair in vision and in numerical values. Pentapeptides consisting of hydrophobic amino acids (LIILL), amino acids with sulfur (CMMCC), and basic amino acids (RKKRR) increased the tensile strength in perm-damaged hair. Pentapeptides with no extra carboxyl/amine groups in R group of amino acids resulted in no significant differences in hair strength and fluorescence yield among hairs treated with alone and with crosslinkers. Pentapeptides with extra carboxyl groups or amine groups enabled further strengthening of hair due to increased bonds within the hair after carbodiimide coupling reaction. The hair repairs of pentapeptides with various amino acid sequences were studied using crosslinking. Depending on the physical characteristics of comprising amino acids, the restoration of damaged hair was observed with tensile strength of hair and fluorescence signals upon cross-sectioned hair in parallel to possibly understand the binding tendency of each pentapeptide within the hair.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3338-3342
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• 2012

Covalent functionalization of a $B_{12}N_{12}$ nano-cage with $CO_2$ molecule has been investigated using density functional theory in terms of energetic, geometric, and electronic property analyses. Results show that besides two physisorption configurations, $CO_2$ preferably tends to perform [2+2] addition on B-N bonds of the cluster which are shared between six-membered and four-membered rings, releasing energy of 14.99 kcal/mol for adsorption of the first $CO_2$ and of 15.45 kcal/mol for the second one (per each molecule). On the basis of calculated density of states, we have found that the electronic properties of the physisorbed $B_{12}N_{12}$ by $CO_2$ have not changed, while slight changes have been predicted in the functionalized cases. Present results might be helpful to provide an effective way to modify the $B_{12}N_{12}$ properties for further purifications and applications.

• Journal of the Korean Applied Science and Technology
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• v.15 no.3
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• pp.61-66
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• 1998

Cyclodextrin are obtained from starch by enzymatic degradation. The three best characterize forms are ${\alpha}$, ${\beta}$, ${\gamma}$ cyclodextrin consisting of 6, 7, and 8 D-glucose units, respectively. Each of the glucose units are in the rigid C1 chair conformation and are linked by ${\alpha}$ 1,4 bonds. This geometry gives the cyclodextrin the shape of a hollow truncated cone with the wider side formed by the secondary 2- and 3-hydroxy groups and the narrower side by the primary 6-hydroxy group. The most characteristics property of the cyclodextrin is their ability to form inclusion complexes with a wide range of guest moleculars. We syntheses per-6-substituted ${\beta}$-cyclodextrin derivatives and investigate structures, spectrospcopic properties. The substituted materials are piperidine, piperazin, morphorine. The synthetic compound showed a good solubility than natural ${\beta}$ cyclodextrin in organic solvents such as methylene chloride, methanol, ethanol, etc.