• Journal of Astronomy and Space Sciences
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• v.9 no.1
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• pp.41-51
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• 1992

Photoelectric observations of close binary stars, AO Cam and AW Cam, were made during the 1984 observing season with the 61cm reflector at the Sobaeksan Observatory. One time of primary minimum for AO Cam and three primary epochs for AW Cam were derived from the observations of these two systems. Times of minimum light of these two binaries collected from literature were analyzed with a least square fitting method. New improved light elements for AO Cam and AW Cam were determined. The orbital period of AO Cam had been constant from Octobar, 1980 (JD 244520) to February, 1985 (JD 2446107). However, one secondary time of minimum (JD 2447864.7879) of AO Cam published recently by Mullis and Faulkner(1991) shows large deviation of about 4.6 minutes ($0^d.0032$) from the one predicted by our new light elements. Future observations of times of minima for this system are needed to test this period change. The orbital period of AW Cam has been constant as P=$0^d.77134645$ for about sixty years from the early 1930's to the present.

• Journal of the Korean Chemical Society
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• v.59 no.2
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• pp.125-131
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• 2015

Inhibition effects of histidine (His), methionine (Met) on the corrosion of nickel were investigated in deaerated 0.5 M HCl and 0.5 M $H_2SO_4$ solution. All the inhibition efficiency for the nickel corrosion depended on the anodic inhibition. Amino acid adsorption process on nickel surface in the solution of HCl can be explained by modified Langmuir isotherm, however, in the solution of $H_2SO_4$ by Temkin logarithmic isotherm due to the interaction between the adsorbed molecules. The molecule of histidine dissolved in HCl-solution were physically adsorbed due to the electrostatic interaction between the surface of {$Ni-Cl^-$} and the {$-NH{_3}^+$} and {$-NH^+=$} of His. However the other cases of adsorption in this investigation can be explained by chemical adsorption between the empty d-orbital of Ni and the lone pair of electron in His and Met.

• Journal of the Korean Chemical Society
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• v.53 no.3
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• pp.266-271
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• 2009

In the recently synthesized rare earth transition metal carbide $La_7O_{s4}C_9$ one finds one-dimensional organometallic $[O_{s4}C_9]^{21-}$ polymers embedded in a $La^{3+}$ ionic matrix. The electronic structure of the polymeric $[O_{s4}C_9]^{21-}$ chain was investigated by density of states (DOS) and crystal orbital overlap population (COOP), using the extended Huckel algorithm. A fragment molecular orbital analysis is used to study the bonding characteristics of the $C_2$ units in $La_7O_{s4}C_9$ containing $C_2$ units and single C atoms as well. The title compound contains partially filled Os and carbon bands leading to metallic conductivity. As the observed distances already indicated, the calculations show extensive Os-C interactions. The C-C bond distance in the diatomic $C_2$ units ($d_{C-C}$=131 pm) in the solid is significantly increased relative to $${C_2}^{2-}$$ or acetylene, because antibonding $1{\pi}_g$ orbitals are partially filled by the Os-$C_2(1\;{\pi}_g)$ bonding contribution found at and below the Fermi level.

• Journal of Magnetics
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• v.20 no.4
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• pp.331-335
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• 2015

The ferromagnetic and electronic structure for the $Al_xGa_{1-x}P$ and Mn-doped $AlGaP_2$ was studied by using the self-consistent full-potential linear muffin-tin orbital method. The lattice parameters of un-doped $Al_xGa_{1-x}P$ (x = 0.25, 0.5, and 0.75) were optimized. The band-structure and the density of states of Mn-doped $AlGaP_2$ with or without the vacancy were investigated in detail. The P-3p states at the Fermi level dominate rather than the other states. Thus a strong interaction between the Mn-3d and P-3p states is formed. The ferromagnetic ordering of dopant Mn with high magnetic moment is induced due to the (Mn-3d)-(P-3p)-(Mn-3d) hybridization, which is attributed by the partially filled P-3p bands. The holes are mediated with keeping their 3d-characters, therefore the ferromagnetic state is stabilized by this double-exchange mechanism.

• Bulletin of the Korean Chemical Society
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• v.15 no.11
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• pp.980-984
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• 1994

Monomeric rhodium and iridium diimine complexes $Cp^*M(HNRNH)(Cp^*$ = 1,2,3,4,5-pentamethylcyclopentadienyl : (M=lr; R=o-$C_6H_4 (1a), 4,5-(CH_3)_2-C_6H_2-1,2 (1b), 4,5-(Cl)_2-C_6H_2-1,2$ (1c), NCC=CCN-1,2 (1d): M=Rh; R=NCC=CCN-1,2 (1e)) have been synthesized from $[CP^*MCl_2]_2$ and 2 equiv. of diamine in the presence of $NEt_3$. The Crystal structure of 1a was determined by X-ray diffraction method : 1a was crystallized in the monoclinic system, space group $P2_{1/c}$, with lattice constants a=9.543 (1) ${\AA}$, b=16.286 (1) ${\AA}$, c=10.068 (1) ${\AA}$ and ${\beta}$=99.25 (1), with Z= 4. Least-squares refinement of the structure led to R factor of 0.049. The coordination sphere of rhodium and iridium can be described as a 2-legged piano-stool. All complexes are highly colored. Electrochemical studies show that 1d and 1e display quasi-reversible reduction and 1a-1c display irreversible reductions, suggesting that the acceptor orbital might be localized on the diimine ring.

• Journal of the Korean Chemical Society
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• v.30 no.2
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• pp.181-187
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• 1986

It is shown that the substitutive ligand on the photochemical substitution reactions of $trans-Cr^{Ⅲ}N_4XY$ complexes is predicted by considering the total stabilization energy of the hypothetical primary intermediates resulting from the loss of one ligand. The total stabilization energy and one electron energy level of d-orbital are calculated within the framework of angular overlap model. According to the calculated results, the intermediates with larger total stabilization energy are, as expected, more easily produced. Consequently, the relative values of the total stabilization energy are used to decide which of the ligands in $trans-Cr^{Ⅲ}N_4XY$ complexes is preferentially labilized on the lowest energy d-d irradiation. The prediction for the leaving ligand on the photoaquation of $trans-Cr^{Ⅲ}N_4XY$ complexes is consistent.

• Bulletin of the Korean Chemical Society
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• v.18 no.1
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• pp.27-32
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• 1997

The geometries and energies of the isomers in alkyne complexes MCl(PH3)2(η2-C2H2), M=Rh and Ir, are theoretically investigated using ab initio methods at the Hartree-Fock and up to MP4 level of theory and relativistic effective core potentials for Rh and Ir metals. The optimized structures of Rh complexes, 1-3 at MP2/ECP1 level are in good agreement with the related experimental data. The binding energies of C2H2 to d8-metal fragments are computed to be ∼55 kcal/mol. The vinylidene complexes for Rh and Ir metals are calculated to be much lower in energy than the alkyne complexes. The alkyne-vinylidene rearrangement is possible to proceed exothermically through the intermediate hydrido-alkynyl complexes, 2 or 9. Detailed comparison is given about the geometries and relative energies on Rh and Ir isomers at the various level ab initio calculations with orbital analysis.

• Textile Coloration and Finishing
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• v.28 no.2
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• pp.57-62
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• 2016

We have synthesized five novel phthaloperinone dyes via a condensation reaction to be applied as yellow colorants for liquid crystal display(LCD) color filters. The reaction between 1,8-naphthalic anhydride(1a), 4-chloro-1,8-naphthalic anhydride(1b), 4-bromo-1,8-naphthalic anhydride(1c), 3-nitro-1,8-naphthalic anhydride(1d), 4-nitro-1,8-naphthalic anhydride(1e) and 1,2-diaminoanthraquinone(2) proceeded readily giving a product in 72-88% yields. The synthesized dyes were characterized by UV-Vis, mass spectrometry and elemental analysis. The spectral properties and thermal stability of the dyes were examined. The dyes absorb at around 400-450nm. All five dyes showed satisfactory thermal stability: the dyes retain 99-100% of its original weight at $300^{\circ}C$, 98-100% at $350^{\circ}C$, 92-98% at $400^{\circ}C$, and 84-92% at $450^{\circ}C$. We have quantitatively evaluated the reaction mechanism and reactivity of dye molecules by means of Pariser-Parr-Pople Molecular Orbital Method(PPP-MO).

• The Journal of Korean Society for Radiation Therapy
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• v.9 no.1
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• pp.40-45
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• 1997

When therapeutic irradiation is indicated for the orbital tumors, the greatest concern is the risk of radiation-induced cataract. Conjunctival lymphoma is one of the good examples. We would like to report the procedure of the lens shielding device(L.S.D) and the result of irradiated dose to the lens. L.S.D. consistes of two parts : load alloy to attenuate electron beam, and dental acryl which completely covers the lead alloy to avoid discomfort of cornea from contacting directly with cerrobend and side scattering by cerrobend. And for easy location and removal, side bars were made on each side. Radiation doses were meaured with TLD(TLD 3500 Hawshaw). Markus chamber in a polystyrene phantom. The phantom was irradiated with 9MeV electron beams from Clinac 2100C with $6{\times}6cm$ electron cone. The relative dose at 6mm depth where the lens is located was $4.2\%$ with TLD and $5.1\%$ with Markus chamber clinically when 2600 cGy are irradiated to the eyeball, the mapinary dose to the lens will be 109 cGy or 132 cGy, which will significently reduce the cataract.

• Journal of Astronomy and Space Sciences
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• v.22 no.3
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• pp.211-222
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• 2005

Results of 6 nights of CCD VR photometry of the nova-like variable V603 Aquilae (Nova Aquilae 1918) obtained at the Mallorcian 35-cm telescope in July 2004 are reported. The ephemeris for the superhump maximum is Max.HJD=2453213.60546(96)+0.14813(10)E. The waves with $3.^d9,\;1.^d4,\;0.^d135$ are statistically significant, which may be interpreted as the negative superhump-orbital, the beat periods (negative superhump- positive superhump) and the negative superhump with low amplitude, respectively. Another possible time-scale is $0.^d8,$ which has no coincidence with the beat periods. Quasi-periodic oscillations with an effective period of 18 minutes have been detected, which are close to 15.6 minutes reported by some authors. Their effective semi-amplitudes are $^m.045\;and\;0^m.051$ for V and R, respectively. This corresponds to the 0.12 mag excess in the color index V-R as compared with the mean color, which can be understood as the pulsed emission in the hotter inner parts of the accretion disk, similar to that observed in TT Ari and MV Lyr.