• Electrical & Electronic Materials
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• v.7 no.4
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• pp.317-324
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• 1994

In this study, new preparation method of LiCoO$_{2}$ was applied to develop cathode active material for Li rechargeable cell, and followed by X-ray diffraction analysis, electrochemical properties and initial charge/discharge characteristics as function of current density. HC8A72- and CC9A24-LiCoO$_{2}$ were prepared by heating treatment of the mixture of LiOH H$_{2}$O/CoCO$_{3}$(1:1 mole ratio) and the mixture of Li$_{2}$CO$_{3}$/CoCO$_{3}$(1:2 mole ratio) at 850 and 900.deg. C, respectively. Two prepared LiCoO$_{2}$s were identified as same structure by X-ray diffraction analysis. a and c lattice constant were 2.816.angs. and 14.046.angs., respectively. The electrochemical potential of CFM-LiCoO$_{2}$(Cyprus Foote Mineral Co.'s product), HC8A72-LiCoO$_{2}$ and CC9A24 LiCoO$_{2}$ electrode were approximately between 3.32V and 3.42V vs. Li/Li reference electrode. Stable cycling behavior was obtained during the cyclic voltammetry of LiCoO$_{2}$ electrode. According as scan rate increases, cathodic capacity decreases, but redox coulombic efficiency was about 100% at potential range between 3.6V and 4.2V vs. Li/Li reference electrode. Cathodic capacity of HC8A72-LiCoO$_{2}$ was 32% higher than that of CFM-LiCoO$_{2}$ and that of CC9A24-LiCoO$_{2}$ was 47% lower than that of CFM-LiCoO$_{2}$ at 130th cycle in the condition of lmV/sec scan rate. Constant cur-rent charge/discharge characteristics of LiCoO$_{2}$/Li cell showed increasing Ah efficiency with initial charge/discharge cycle. Specific discharge capacities of CFM and HC8A72-LiCoO$_{2}$ cathode active materials were about 93mAh/g correspondent to 34% of theretical value, 110mAh/g correspondent to 40% of theretical value, respectively. In the view of reversibility, HC8A72-LiCoO$_{2}$ was also more excellent than CFM- and CC9A24-LiCoO$_{2}$.

• Korean Journal of Materials Research
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• v.16 no.2
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• pp.106-110
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• 2006

We have investigated the effect of the experimental variables such as temperature and pressure on conformality of Co films deposited over high aspect ratio trenches using $Co_2(CO)_8$ as a precursor. The results show that the conformality of Co films is a strong function of temperature and process pressure. Lowering the pressure and temperature significantly improves the conformality. As the pressure decreases from 0.6 Torr to 0.2 Torr at $50^{\circ}C$, the bottom coverage of Co films over $0.2{\mu}m$ width trenches with an aspect ratio of 13 to 1 significantly increases to 85%. However, further increasing the temperature from 50 to $60^{\circ}C$ at the pressure of 0.2 Torr degrades the bottom coverage to 14%. In contrast, the extremely low pressure of 0.03 Torr allows the excellent conformal deposition of Co films up to $70^{\circ}C$. This can be attributed to the suppression of homogeneous reaction in the gas phase, which can create the intermediate products with high sticking coefficient. In addition, the Co films deposited at $50^{\circ}C$ show the low resistivity with negligible contamination. As a result, the newly developed Co process using MOCVD can be implemented into the next generation devices with complex shapes.

• Horticultural Science & Technology
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• v.19 no.4
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• pp.550-554
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• 2001

'Fuyu' persimmon fruits (Diospyros kaki Thunb.) were seal-packaged in $60{\mu}m$ polyethylene (PE) film bags with various $O_2$ and $CO_2$ combinations (0% $O_2$+5% $CO_2$, 2% $O_2$+5% $CO_2$, 2% $O_2$+8% $CO_2$, 5% $O_2$+5% $CO_2$, 5% $O_2$+10% $CO_2$), and in vacuum and air. They were then stored at $-0.5^{\circ}C$ for 95 days. Changes in fruit weight, firmness, soluble solids, Hunter L and a values, $CO_2$ concentrations, and marketability were investigated at 20-day intervals. A combination of 2% $O_2$ and 5% $CO_2$ as well as the vacuum treatment were effective in maintaining firmness, soluble solids, marketability, and Hunter a value of 'Fuyu' fruits. On the other hand, the treatment of 2% $O_2$ combined with 8% $CO_2$ and vacuum treatment were effective in maintaining fresh weight and Hunter L and a values. The highest marketable quality was maintained when the fruits were vacuum-sealed, although fruits softened severely in the area where two fruits contacted with each other.

• Korean Journal of Materials Research
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• v.28 no.7
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• pp.371-375
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• 2018

The manganese-, nickel-, and aluminum-doped cobalt ferrite powders, $Mn_{0.2}Co_{0.8}Fe_2O_4$, $Ni_{0.2}Co_{0.8}Fe_2O_4$, and $Al_{0.2}CoFe_{1.8}O_4$, are fabricated by the sol-gel method, and the crystallographic and magnetic properties of the powders are studied in comparison with those of $CoFe_2O_4$. All the ferrite powders are nano-sized and have a single spinel structure with the lattice constant increasing in $Mn_{0.2}Co_{0.8}Fe_2O_4$ but decreasing in $Ni_{0.2}Co_{0.8}Fe_2O_4$ and $Al_{0.2}CoFe_{1.8}O_4$. All the $M{\ddot{o}}ssbauer$ spectra are fitted as a superposition of two Zeeman sextets due to the tetrahedral and octahedral sites of the $Fe^{3+}$ ions. The values of the magnetic hyperfine fields of $Ni_{0.2}Co_{0.8}Fe_2O_4$ are somewhat increased in the A and B sites, while those of $Mn_{0.2}Co_{0.8}Fe_2O_4$ and $Al_{0.2}CoFe_{1.8}O_4$ are decreased. The variation of $M{\ddot{o}}ssbauer$ parameters is explained using the cation distribution equation, superexchange interaction and particle size. The hysteresis curves of the ferrite powders reveal a typical soft ferrite pattern. The variation in the values of saturation magnetization and coercivity are explained in terms of the site distributions, particle sizes and the spin magnetic moments of the doped ions.

• Membrane Journal
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• v.25 no.5
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• pp.415-421
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• 2015

$SrCo_{0.8}Fe_{0.1}Nb_{0.1}O_{3-{\delta}}$ oxide was synthesized by solid state reaction method. Dense ceramic membrane was prepared using as-prepared powder by pressing and sintering at $1250^{\circ}C$. XRD result of membrane showed single perovskite structure. The oxygen permeability were measured under 0.21 atm of oxygen partial pressure ($P_{O_2}$) and between 800 and $950^{\circ}C$. The oxygen permeation flux of $SrCo_{0.8}Fe_{0.1}Nb_{0.1}O_{3-{\delta}}$ membrane was increased with the increasing temperature. The maximum oxygen permeation flux was $1.839mL/min{\cdot}cm^2$ at $950^{\circ}C$. Long period permeability experiment was carried out to confirm the phase stability and $CO_2$-tolerance of membrane containing Nb in the condition of air with $CO_2$ (500 ppm) as feed stream at $900^{\circ}C$. The phase stability and $CO_2$-tolerance of $SrCo_{0.8}Fe_{0.1}Nb_{0.1}O_{3-{\delta}}$ were investigated by XRD and TG analysis. The result of $SrCo_{0.8}Fe_{0.1}Nb_{0.1}O_{3-{\delta}}$ which exposed carbon dioxide for 100 hours indicated 8wt% of $SrCO_3$. But it was known that the level of $SrCO_3$ production dose not have a significant effect on oxygen permeability.

• Journal of the Korean Chemical Society
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• v.21 no.1
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• pp.53-59
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• 1977

A method of synthesizing $NaAlCO_3(OH)_2$ (Dawsonite) and $KAlCO_3(OH)_2$, was investigated by blowing $CO_2$ gas into sodium and potassium aluminate solutions. The reactions were accomplished at a temperature of 80 to $90^{\circ}C$, while $CO_2$ gas was blowing into the solutions which the molar ratios of $Na_2O/Al_2O_3,\;and\;K_2O/Al_2O_3$ were 6 to 8 and 8 to 10, respectively. It was observed that highly purified Dawsonite and $KAlCO_3(OH)_2$ are produced when Alumina is present in Boehmite at an equilibrium solid phase with a large amount of $HCO_3^-$ in the solutions. The rational formulas of Dawsonite and $KAlCO_3(OH)_2$synthesized under the conditions should be expressed as $NaAlO(OH)HCO_3\;and\;KAlO(OH)HCO_3$, respectively, by IR analysis. In addition, electron microscopic observation also indicated that Dawsonite in a fibrous crystal and $KAlCO_3(OH)_2$ in a needleshaped crystal.

• Journal of the Korean Electrochemical Society
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• v.14 no.2
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• pp.98-103
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• 2011

[ $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ ]cathode material for lithium secondary battery is obtained using co-precipitation method. To determine the optimal metal solution concentration value, the CSTR coprecipitation was carried out at various concentration values(1-2 mol/L). The surface morphology of coated samples was characterization by SEM(scanning electron microscope) and XRD (X-Ray Diffraction)analyses. Impedance analysis and cyclic voltammogram presented that internal resistance of the cell was dependent upon the concentration of metal solution. such data is very helpful in determining the optimal content of metal solution concentration to enhancing electrochemical property by adjusting powder size distribution and crystal structure.

• Bulletin of the Korean Chemical Society
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• v.21 no.11
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• pp.1133-1137
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• 2000

Gibbs ensemble Monte Carlo simulations were performed to calculate the vapor- liquid coexistence properties for the binary mixtures $CO_2/C_3H8$, $CO_2/CH_3OCH_3$, and $CO_2/CH_3COCH_3.$ For all the molecules the potential between sites in different molecules was simply calculated by the Lennard-Jones potential. Density of the mixture, composition of the mixture, the pressure-composition diagram, the chemical potential of component, and the radial distribution function were calculated at vapor- liquid equilibrium. The composition and the density of both vapor and liquid from simulation agreed considerably well with the experimental values over a wide range of pressures. The radial distribution functions in the liquid mixtures showed that $CO_2$ molecules tended to form cluster with each other and $C_3H8$ molecules also aggregated each other due to the weak interaction between $CO_3$ and $C_3H8$ molecule. However the interaction potentials between the same components were similar to those between the different components in the liquid mixtures $CO_2/CH_3OCH_3$ and $CO_2/CH_3COCH_3$.

• Parasites, Hosts and Diseases
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• v.35 no.1
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• pp.25-30
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• 1997

Gymnophclloides seoi is a human intestinal trematode prevalent on southwestern islands in Korea. In the present study, we investigated whether G. seoi metacercariae can grow and develop into adults by in vitro cultivation. The metacercariae were obtained from naturally infected oysters, and cultured in uitro for 5 days under three conditions; $37^{\circ}C/5%{\;}CO_2,{\;}41^{\circ}C/8%{\;}CO_2,{\;}or{\;}41^{\circ}C/15%{\;}CO_2$, in NCTC 109 complete media containing 20% FBS and 1% antibiotics-antimycotics. The degree of worm growth and development was compared with that grown in uiuo of C3H mice. The length of the worms cultivated in uitro was $200-300{\;}\mu\textrm{m}$, not significantly different from metacercariae, whereas the length of the worms recovered from C3H mice was significantly larger, $300-400{\;}\mu\textrm{m}$. The worms produced eggs when grown in C3H mice or cultured in vitro for 2 days under $41^{\circ}C/8%{\;}CO_2{\;}or{\;}41^{\circ}C/5%{\;}CO_2$, but not when cultured under 37$^{\circ}C/5%{\;}CO_2$. Among the in vitro conditions, $41^{\circ}C/15%{\;}CO_2$ was best for egg Production, although the number of eggs was about half of worms obtained from C3H mice. In conclusion, in vitro cultivation of G. semi metacercariae into egg-pioducing adults was partially successful under culture conditions of $41^{\circ}C/5%{\;}CO_2{\;}or{\;}41^{\circ}C/8%{\;}CO_2$.

• Journal of Welding and Joining
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• v.12 no.1
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• pp.51-58
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• 1994

Amount of spatter, welding conditions and welding costs were investigated for MAG welding. $CO_2$, Ar+18%;$CO_2$ and Ar+8%$O_2$ were used for shielding gases. As results, arc characteristics and appropriate range for welding were obtained. Amount of spatter in Ar+18%$CO_2$ gas welding was 20% of that of $CO_2$ welding, and Ar+8%$O_2$ was 10% of that of $CO_2$ welding. Therefore by using Ar+18%$CO_2$and Ar+8%$O_2$ gases, welding costs could be reduced compared with $CO_2$ welding due to avoiding spatter.