• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.21 no.10
• /
• pp.923-929
• /
• 2008

On the piezoelectric polymer, PVDF (poly vinylidene fluoride), the transparent conducting oxide (TCO) electrode material thin film was deposited by roll to roll sputtering process mentioned as a mass product-friendly process for display application. The deposition method for ITO Indium Tin Oxides) as our TCO was DC magnetron sputtering optimized for polymer substrate with the low process temperature. As a result, a high transparent and good conductive ITO/PVDF film was prepared. During the process, especially, the gas mixture ratio of Ar and Oxygen was concluded as an important factor for determining the film's physical properties. There were the optimum ranges for process conditions of mixture gas ratio for ITO/PVDF From these results, the doping mechanism between the oxygen atom and the metal element, Indium or Tin was highly influenced by oxygen partial pressure condition during the deposition process at ambient temperature, which gives the conductivity to oxide electrode, as generally accepted. With our studies, the process windows of TCO for display and other application can be expected.

• Journal of the Korean Ceramic Society
• /
• v.28 no.8
• /
• pp.603-610
• /
• 1991

An oxygen deficient perovskite (CaLa)(MgMn)O5.43, with the cubic unit cell parameter of 3.826$\AA$, was prepared 115$0^{\circ}C$ for 10 hrs under the ambient oxygen gas pressure. The average oxidation state of manganese was determined to be 3.86 by the iodometric titration, so that the perovskite could be formulated as (CaLa) ({{{{ { MgMn}`_{ chi } ^{II } }}{{{{ { Mn}`_{ y} ^{III } }}{{{{ { Mn}`_{1- chi -y } ^{IV } }})O5.43 (2x+y=0.14). From X-ray photoelectron spectroscopy, the manganese ions in the lattice are mostly tetravalent, but two paramagnetic configurations were observed in the EPR spectrum: One sharp isotropic signal with hyperfines (ΔH 50 G, g=1.997$\pm$0.002 and │A│=82(4)$\times$10-4 cm-1) and a broad isotropic one (ΔH 1600 G, g=1.994$\pm$0.002), those which correspond respectively to Mn(II) and Mn(IV) ions. According to the magnetic susceptibility measurement, it follows the Curie-Weiss law from 20 K up to room temperature with $\mu$eff=5.23 $\mu$B, which is relatively larger than spin-only value({{{{ { mu }`_{eff} ^{s.o } }}=4.04 $\mu$B) due to the effect of weak ferromagnetic coupling. Such a result is in accord with a theory of semicovalence exchange.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.2 no.3
• /
• pp.90-98
• /
• 1998

The vaporization process of liquid oxygen(LOX) at high pressure environment is numerically investigated. The present vaporization model can account for the high-pressure effects such as ambient gas solubility, real gas behavior and variable properties. The predicted phase-equilibrium compositions for $N_2$/$H_2$ and $O_2$/He system are well agreed with experimental data. The LOX vaporization characteristics is parametrically studied for wide range of the operating conditions encountered in the high-pressure combustion process of liquid rocket engine.

• Journal of the Korean Society of Combustion
• /
• v.18 no.4
• /
• pp.1-11
• /
• 2013

The oxy-fuel combustion is $CO_2$ capture technology that uses mixture of pure $O_2$ and recirculated exhaust as oxidizer. Currently some Oxy-fuel power plants demonstration project is underway in worldwide. Meanwhile research project for converting 125 MWe Young-Dong power plant to 100 MWe oxy-fuel power plants is progress. In this paper, 1 D process analytical approach was applied for conducting process design and operating parameters sensitivity analysis for oxy-fuel combustion of Young-Dong power plant. As a result, appropriate gas recirculation rates was 74.3% that in order to maintain normal rating superheater, reheater steam temperature and boiler heat transfer patterns. And boiler efficiency 85.0%, CPU inlet $CO_2$ mole concentration 71.34% was predicted for retrofitted boiler. The oxygen concentration in the secondary recycle gas is predicted as 27.1%. Meanwhile the oxygen concentration 22.4% and moisture concentration 5.3% predicted for primary recycle gas. As the primary and secondary gas recirculation increases, then heat absorption of the reheater is tends to increases whereas superheater side is decreased, and also the efficiency is tends to decrease, according to results of sensitivity analysis for operating parameters. In addition, the ambient air ingression have a tendency to lead to decline of efficiency for boiler as well as decline of $CO_2$ purity of CPU inlet.

• Korean Journal of Materials Research
• /
• v.25 no.10
• /
• pp.543-546
• /
• 2015

$TiO_2$ nanowires were grown by thermal oxidation of TiO powder in an oxygen and nitrogen gas environment at $1000^{\circ}C$. The ratio of $O_2$ to $N_2$ in an ambient gas was changed to investigate the effect of the gas ratio on the growth of $TiO_2$nanowires. The oxidation process was carried out at different $O_2$/$N_2$ ratios of 0/100, 25/75, 50/50 and 100/0. No nanowires were formed at $O_2$/$N_2$ ratios of less than 25/75. When the $O_2$/$N_2$ ratio was 50/50, nanowires started to form. As the gas ratio increased to 100/0, the diameter and length of the nanowires increased. The X-ray diffraction pattern showed that the nanowires were $TiO_2$ with a rutile crystallographic structure. In the XRD pattern, no peaks from the anatase and brookite structures of $TiO_2$were observed. The diameter of the nanowires decreased along the growth direction, and no catalytic particles were detected at the tips of the nanowires which suggests that the nanowires were grown with a vapor-solid growth mechanism.

• Korean Journal of Materials Research
• /
• v.15 no.5
• /
• pp.323-333
• /
• 2005

Effects of gases to growth of $SiO_2$ nanowires were characterized. $N_2$, Ar, and $O_2$ gas's effect were determined. $SiO_2$ nanowires growth scheme was varied by kind and flow rates of gases because of amounts of $O_2$. Flow rates of gases and kind of substrates affected nanowires' diameters, lengths and morphologies of grown nano wires. With increasing flow rates of gases, nanowire's diameter increased because of additional VS and SLS reactions. By TEM characterization, We knows that, grown $SiO_2$ nanowires on Si substrate showed two shell structures. These shapes of nanowires were formed by reaction of additional SLS growth. Grown $SiO_2$ nanowires showed blue luminescence by PL characterization These Blue luminescence was due to quantum confinement effect and oxygen vacancies in the nanowires.

• Electrical & Electronic Materials
• /
• v.9 no.4
• /
• pp.357-363
• /
• 1996

The superconducting properties of YBa$_{2}$Cu$_{3}$$O_{7-x}$(YBaCuO) thin films prepared by laser ablation have been investigated. The x-ray diffraction patterns of the films were substantially different from one another. The Y and Ba oxides are formed by the collisions with oxygen molecules. On the other hand, the Cu oxide is mainly formed at initial stage of the laser irradiation. The YBaCuO films manufactured on MgO(100) substrate were indicated T$_{c}$(zero)=90 K, T$_{c}$(onset)=92 K, and J$_{c}$=3.5*10$^{5}$ A/cm$^{2}$(at 77.3K). The optimum conditions were found to be a substrate temperature of 710.deg. C, an energy density of 2 J/cm$^{2}$, and a target-substrate distance of 60mm in an oxygen partial pressure of 200 mTorr.0 mTorr.

• Journal of the Semiconductor & Display Technology
• /
• v.9 no.3
• /
• pp.53-58
• /
• 2010

In this study, we have investigated the effect of the ambient gases on the characteristics of IZO thin films for the OLED (organic light emitting diodes) devices. For this purpose, IZO thin films were deposited by RF magnetron sputtering under various ambient gases (Ar, $Ar+O_2$ and $Ar+H_2$) at $150^{\circ}C$. In order to investigate the influences of the oxygen and hydrogen, the flow rate of oxygen and hydrogen in argon mixing gas has been changed from 0.1sccm to 0.5sccm, respectively. All the samples show amorphous structure regardless of ambient gases. The electrical resistivity of IZO film increased with increasing flow rate of $O_2$ under $Ar+O_2$ while under $Ar+H_2$ atmosphere the electrical resistivity showed minimum value near 0.5sccm of $H_2$. All the films showed the average transmittance over 85% in the visible range. The OLED device was fabricated with different IZO substrates made by configuration of IZO/${\alpha}$-NPD/DPVB/$Alq_3$/LiF/Al to elucidate the performance of IZO substrate. OLED devices with the amorphous-IZO (a-IZO) anode film show better current densityvoltage-luminance characteristics than that of OLED devices with the commercial crystalline-ITO (c-ITO) anode film. It can be explained that very flat surface roughness and high work function of a-IZO anode film lead to more efficient hole injection by reduction of interface barrier height between anode and organic layers. This suggests that a-IZO film is a promising anode materials substituting conventional c-ITO anode in OLED devices.

• Journal of Powder Materials
• /
• v.16 no.4
• /
• pp.243-248
• /
• 2009

Carbon-coated Cu nanopowders with core/shell structure have been successfully fabricated by pulsed wire evaporation (PWE) method, in which a mixed gas of Ar/$CH_4$ (10 vol.%) was used as an ambient gas. The characterization of the samples was carried out using x-ray diffraction (XRD), scanning electron microscope (SEM), and high resolution transmission electron microscope (HRTEM). It was found that the nanoparticles show a spherical morphology with the size ranging of 10-40 nm and are covered with graphite layers of 2-4 nm. When oxygen-passivated Cu nanopowders were annealed under flowing argon gas (600 and 800$^{\circ}C$), the crystallinity of $Cu_2O$ phase and the particle size gradually increased. On the other hand, carbon-coated Cu nanopowders remained similar to as-prepared case with no additional oxide or carbide phases even after the annealing, indicating that the metal nanoparticles are well protected by the carbon-coating layers.

• Transactions of the Korean hydrogen and new energy society
• /
• v.28 no.4
• /
• pp.384-391
• /
• 2017

Effects of operating variables on solid circulation rate were measured and discussed using two-interconnected circulating fluidized bed system at ambient temperature and pressure. OCN 706-1100 particles were used as oxygen carrier. The measured solid circulation rates increased as the lower loop seal gas flow rates and the solid height in the fuel reactor increased. Suitable operating conditions to avoid choking of the air reactor were confirmed. Continuous long-term operations of steady-state solid circulation were also demonstrated at two different conditions based on the operating window.