• Journal of the Korean Vacuum Society
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• v.6 no.4
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• pp.348-353
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• 1997

Hydrogenated amorphous carbon(a-C:H) films were deposited on p-type Si(100) by DC saddle-field plasma enhanced CVD to investigate the effect of substrate bias on optical properties and structural changes. They were deposited using pure methane gas at a wide range of substrate bias at room temperature and 90 mtorr. The substrate bias voltage ($V_s$) was employed from $V_s=0 V$ to $V_s=400 V$. The information of optical properties was investigated by photoluminescence and transmitance. Chemical bondings of a-C:H have been explored from FT-IR and Raman spectroscopy. The thickness and relative hydrogen content of the films were measured by Rutherford backscattering spectroscopy (RBS) and elastic recoil detection (ERD) technigue. The growth rate of a-C:H film was decreased with the increase of $V_s$, but the hydrogen content of the film was increased with the increase of $V_s$. The a-C:H films deposited at the lowest $V_s$ contain the smallest amount of hydrogen with most of C-H bonds in the of $CH_2$ configuration, whereas the films produced at higher $V_s$ reveal dominant the $CH_3$ bonding structure. The emission of white photoluminescence from the films were observed even with naked eyes at room temperature and the PL intensity of the film has the maximum value at $V_s$=200 V. With $V_s$ lower than 200 V, the PL intensity of the film increased with V, but for V, higher than 200 V, the PL intensity decreased with the increase of $V_s$. The peak energy of the PL spectra slightly shifted to the higher energy with the increase of $V_s$. The optical bandgap of the film, determined by optical transmittance, was increased from 1.5 eV at $V_s$=0V to 2.3 eV at $V_s$=400 V. But there were no obvious relations between the PL peak and the optical gap which were measured by Tauc process.

• Journal of The Korean Astronomical Society
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• v.13 no.1
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• pp.15-26
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• 1980

The BV-photographic photometry was made for 1714 stars (V<19.5) in NGC 6752. The C-M diagram of this cluster shows an unusually extended blue horizontal branch $(V=13.5{\sim}17.8)$ with a wide gap $(V=16{\sim}16.7)$ and the well defined giant branch with gaps at V=13.85 and 16.2. The turnoff point is defined at $V=17.25{\pm}0.15$ and (B-V) = $0.46{\pm}0.02$. If we take $V_{HB}=13.85$ for NGC 6752, then ${\Delta}V=2.80,\;(B-V)_{0,g}=0.76\;and\;{\Delta}V_{TO}=3.40$ and the chemical abundance is estimated to be [Fe/H]=-1.67 or $Z=4.3{\times}10^{-4}\;and\;Y=0.26$. Some other physical parameters of this cluster are derived and compared with those for the well observed clusters M 3, M 13, M 15 and M 92.

• Food Science and Biotechnology
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• v.17 no.2
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• pp.257-261
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• 2008

Previous studies have suggested a possible correlation between cell surface hydrophobicity (CSH) and stress tolerance in Bifidobacterium. In this study, the relationship was examined between CSH and environmental stress tolerance in Lactobacillus spp. By measuring the adhesion to hexadecane, 2 Lactobacillus fermentum strains- KLB 261 and KLB 231 were found to have high and low CSH, respectively. To measure their tolerance to various stresses, cells were subjected to salt (2 M NaCl), acid (pH 2), $H_2O_2$ (0.01 %, v/v), ethanol (20%, v/v), heat ($60^{\circ}C$), and cold ($-20^{\circ}C$). Compared with KLB 231, the hydrophobic KLB 261 was found to be much more resistant to the various stresses examined. After being subjected to different stresses for a period of time, KLB 261 and KLB 231 showed 50 and 0% survivability in 2 M NaCl, 108.2 and 0.6% in 0.01 %(v/v) $H_2O_2$, 40.2%(v/v), and 3.7% at $60^{\circ}C$ incubation, 4 and 0.6% at $-20^{\circ}C$, 12.9 and 0.1 % in pH 2, 33.8 and 0.2% in 20%(v/v) ethanol, respectively. Autoaggregation test and morphological observation were also conducted in an attempt to explain these differences. These results suggested that high CSH could strengthen the stress tolerance of lactobacilli.

• Journal of Chest Surgery
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• v.17 no.1
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• pp.157-166
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• 1984

These biologic test procedures are designed to test the suitability of P.V.C. made in Korea intended for parenteral preparation, which were based on the U.S. Pharmacopeia XIX "Biologic Test-Plastic Container", Official from July 1, 1975. Healthy adult human blood and rabbits weighing 2\ulcorner.2Kg were used for test materials. Sample P.V.C. were sampled from the medical equipments made in Korea randomly and Control P.V.C. were sampled from the standardized Cobe and Polystan P.V.C. tubes. P.V.C. extract was prepared from a homogeneous P.V.C. samples by incubating 60 square centimeters of the sample per 20 millimeters of sterile pyrogen-free saline at 70\ulcorner for 72 hours or autoclaving at 120\ulcorner for 1 hour. The Implantation Test was designed to evaluate the reaction of living tissue to the plastic by the method of the implantation of the Sample itself into animal tissue. The Systemic Injection Test, the Intracutaneous Test, and the remainders were designed to determine the biological response of animals to plastics by the single-dose injection of specific extracts prepared from a Sample. The results are as follows; 1.Implantation Test - No significant difference for reactions was noted between the Sample treated animal and the Control after 72 hours of implantation. 2.Systemic Toxicity Injection Test - No sign of toxicity and/or death immediately after injection and at 4, 24, 48 hours respectfully after injection. 3.Intracutaneous Test - None of the animals treated with the Sample showed a significantly greater reaction than the observed in the animals treated with Blank. 4.Pyrogen Assay-Only one animal treated with the Sample showed the maximal rise of rectal temperature about 0.2\ulcorner after 3 hours of injection, but remainders showed no change. 5.Hemolytic Index - The positive Control tube of distilled water exhibited complete hemolysis while the negative Control tube and P.V.C. extract were negative demonstrating no hemolysis. 6.Cell Morphology of Erythrocytes and Leukocytes on Stored, Heparinized Human Blood -- There was no significant difference in the morphology of either the Control or Sample extract. 7.Clotting Mechanism of Human Blood in vitro - After allowing to the P.V.C. extract at room temperature for 5 Hours and at 10\ulcorner for 24 hours, there was no appreciable difference in Prothrombin Time under these conditions. 8.Clotting Mechanism of Rabbit in vivo - At the termination of 5 days after intraperitoneal injection of the P.V.C. extract, no significant changes in Clotting Time were observed. According to the above results, it could be concluded that the P.V.C. made in Korea was acceptable for parenteral preparation, especially treated with physiologic saline and/or human blood.man blood.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.5
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• pp.167-173
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• 2023

Li₃V₂(PO₄)₃ and Li₃V₂(PO₄)₃/C composite with single phase monoclinic structure for the cathode materials are successfully synthesized by direct co-precipitation method using N₂H₄·H₂O as the reducing agent and alginic acid as the carbon source, and their electrochemical properties were compared. The particles with approximately 1~2 ㎛ size and the uniform spherical-like morphology of the narrow particle size distribution were obtained. In addition, the residual carbon can also improve the electrical conductivity. The Li₃V₂(PO₄)₃/C composite has improved initial specific discharge capacity and excellent cycle characteristics to maintain capacity stably than Li₃V₂(PO₄)₃. The results indicate that the reducing agent and carbon composite can affect the good crystallinity and electrochemical performance of the cathode materials.

• Journal of Surface Science and Engineering
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• v.25 no.6
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• pp.293-298
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• 1992

Various vanadium-oxide thin films were deposited by e-beam and thermal evaporation of V2O5, V2O3, and VO2 powders. Films with thickness of $2000\AA$ were subjected to annealing at $300^{\circ}C$~$450^{\circ}C$ in N2 atmosphere for the crystallization and desification purposes. For the films deposited from V2O5 and VO2 sources, sources, Magneli (VnO2n-1$ 4\leq$ $n\leq$ 8) and VO2 phase appeared at $300^{\circ}C$, respectively, but VO2 phase also transformed into Magneli phase at $450^{\circ}C$ by severe reduction. On the contrary, VO2/VO mixed phases resulted from congruent evaporation of V2O3 unchanged after the same annealing treatment due to the balanced reduction and oxidation of VO2 and VO whcih have different equilibrium O2 pressures. It is suggested that the annealing in the controlled oxidation atmosphere or the deposition using mixed oxide sources are necessary to get the film containing VO2 phase.

• Korean Journal of Crystallography
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• v.5 no.1
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• pp.1-6
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• 1994

Two possible space groups of the comfound, VP6N3018C24H:60, are: P 1, a=14.022(1), b=12.644(2), c= 12.640(1)A, a=8038(1), B=102.12(1), r=102.16(1), V=2124.1A3, Z=2, μ=0.47cm-1, d=1.46g/cm3, R=0.083 for 3350 independent reflections with Fo>4o IFI, and C2/c, a=19.32(2), b=16.32(2), c=14.02(1)A, B=105.98(5), β=105.98(5), V=4248.2A3, Z=4 R=0.083 for 1590 independent reflections with Fo>4c IFoI . In the space group P T, there are two monlecules in a unit cell. Vanadium atoms in the two monlecules occupy the two different special positions such that the complete monlecules are accomplished by the two independent center of symmetry. Therefore two different half molecules of bis(trimetaphosphate)vanadate and three molecules of tetraethylammonium are the asymmetric unit in a unit cell. In the space group C2/c, however, the vanadium atom is located at a special position with centrosymmetry, and a two-fold symmetry axis passes through C2/c, N2 and C25 atoms. Therefore the asymmrtic unit in a unit cell consists of a half molecule of bis(trimetaphosphate)vanadate and one and a half molecules of tetraethylammonium. All the molecular conformations in both space groups are very similar: six oxygen atoms coordinated to a vanadium atom in the bi s(trimetaphosphate)vanadate molecule form an octahedron and the four carbon atoms bonded to a nitrogen atom in the tetraethylammonium molecule are disordered so that the eight carbon atoms around nitrogen atom exhibit an irregular dodecahedral form.

• Journal of Surface Science and Engineering
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• v.39 no.3
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• pp.87-92
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• 2006

The characteristic of interface layer and the effect of bias voltage on the microstructure of c-BN films were studied in the microwave plasma hot filament C.V.D process. c-BN films were deposited on a high speed steel(SKH-51) substrate by hot filament CVD technique assisted with a microwave plasma to develop a high performance of resistance coating tool. c-BN films were obtained at a gas pressure of 20 Torr, vias voltage of 300 V and substrate temperature of $800^{\circ}C$ in $B_2H_6-NH_3-H_2$ gas system. It was found that a thin layer of hexagonal boron nitride(h-BN) phase exists at the interface between c-BN layer and substrate.

• Journal of the Korean Chemical Society
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• v.30 no.2
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• pp.231-236
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• 1986

Oxidation of $[Mo_2O_4(C_2O_4)_2(OH_2)_2]^{2-}$ with hydrogen chromate yields the molybdenum (VI) complex, $[Mo_2O_4(C_2O_4)_2(OH_2)_2]^{2-}$. Stoichiometry for the reaction of $[Mo_2O_4(C_2O_4)_2(OH_2)_2]^{2-}$ with hydrogen chromate are expressed as ${3Mo_2}^V+2Cr^{VI}\;{\rightleftharpoons}\;{3Mo_2}_{VI}+2Cr^{III}$. Observed rate constants are dependent on $[H+]^2$. The kinetic data are consistent with a mechanism in which three successive single-electron steps convert $Cr^{VI}$to $Cr^{III}$ by way of intermediate Cr^V$ and $Cr^{IV}$. Mechanism of the reaction are presented and discussed.

• Fire Science and Engineering
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• v.15 no.3
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• pp.44-48
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• 2001

In this study, we analyzed the $CH_4$and $C_4$$H_{10}$ sensitivity measurement and voltage variation using catalytic type gas sensor characteristics in catalytic combustion type gas detecter sensors. Gas detector shall operate as intended when exposed for 24 hours to air having a relative humidity of 65 percent at a temperature of $20^{\circ}c$ and humidity of 85 percent at a temperature of $40^{\circ}c$. The gas detecter sensors are to be subjected to operation for 210 days in an area that has been determined to be equivalent to a typical residential atmosphere with an air velocity of 50 cm/sec. The source of energy for a gas detector sensors employing a supplementary basic circuit is energized from a seperate source of supply direct applied voltage 2.1V, 2.2V, 2.3V. As a result, it was confirmed that the relative humidity and temperature by regression each analysis, compared to the isobutane characteristic graph and methane characteristic graph by a relative humidity of 65% and 85% at a temperature($20^{\circ}c$, $40^{\circ}c$) show a similar linear pattern on the whore.