• Journal of the Korean Ceramic Society
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• v.38 no.9
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• pp.787-793
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• 2001

$La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_{3-{\delta}}$ membranes were fabricated by solid-state reaction. We investigated sintering behavior and oxygen permeation flux as a function of time-on-stream, temperature and upstream oxygen partial pressure. The oxygen was permeated at temperatures form 750$^{\circ}$C to 950$^{\circ}$C by mixed conducting through oxygen vacancy diffusion in the dense membrane. The oxygen permeation flux through the membrane were about 0.1ml/$cm^3{\cdot}$min at 850$^{\circ}$C. A constant time was required for reaching stable oxygen flux, and oxygen partial pressure affected the oxygen permeation fluxes.

• Korean Journal of Adult Nursing
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• v.12 no.2
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• pp.234-244
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• 2000

It is widely recognized that manipulation of body position takes advantage of the influences of gravity for improving oxygenation. The study aims to determine the effects of positioning(supine, prone, right lateral decubitus and left lateral decubitus positions) applied to the mechanically ventilatory acute respiratory failure patients on arterial oxygen partial pressure($PaO_2$), alveolar arterial oxygen tension difference($AaDO_2$), mean aterial pressure, peak inspiratory pressure and plateau pressure. Thirty two acute respiratory failure patients admitted to the medical intensive care unit at Kangnam St. Mary's Hospital, The Catholic University of Korea from March 1997 to January 1998, were divided into three groups by radiographic evidence of unilateral or bilateral lung disease. In group 1 with dominant right lung disease were twelve subjects, group 2 with dominant left lung disease had eight subjects and group 3 had twelve subjects with bilateral lung disease. The variables were measured in 30 minutes after each position of supine, prone, good lung down lateral decubitus and sick lung down lateral decubitus position. The position order was done at random by Latin squre design. The results are as follows; 1) With group 1 patients, the $PaO_2$ in the left lateral decubitus and prone position were $126.8{\pm}30.8$ mmHg and $106.7{\pm}36.8$ mmHg, respectively(p=0.0001). 2) With group 2 patients, the $PaO_2$ in the prone and the right lateral decubitus position were $121.7{\pm}44.7$ mmHg and $118.5{\pm}31.7$ mmHg, respectively (p=0.0018). 3) With group 3 patients, the $PaO_2$ was $143.6{\pm}36.6$ mmHg in the prone position (p=0.0001). 4) With group 1 patients, the $AaDO_2$ in the left lateral decubitus and the right lateral decubitus position were $178.1{\pm}29.7$ mmHg and $233.1{\pm}24.4$ mmHg, respectively(p=0.0001). 5) With group 2 patients, the $AaDO_2$ in the prone and the left lateral decubitus postion were $184.0{\pm}39.5$ mmHg and $231.0{\pm}23.9$ mmHg, respectively(p=0.0019). 6) With group 3 patients, the $AaDO_2$ in the prone and the supine postion were $377.1{\pm}35.6$ mmHg and $435.7{\pm}13.1$ mmHg, respectively (p=0.0001). 7) There were no differences among the mean arterial pressure, peak inspiratory pressure and plateau pressure for each of the supine, prone, left lateral decubitus and right lateral decubitus position. The results suggest that oxygenation may improve in mechanically ventilatory patients with unilateral lung disease when the position is good lung dependent and prone, and patients with bilateral lung disease when the position is prone without any effects on the mean arterial pressure and airway pressure. It is suggested that body positions improve ventilation/perfusion matching and oxygenation need to be specified in patient care plans.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.4
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• pp.113-118
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• 2019

In this study, we investigated the growth of single-crystallinity α-Ga₂O₃ thin films on c-plane sapphire substrates using halide vapor pressure epitaxy. We also found the optimal growth conditions to suppress the phase transition of α-Ga₂O₃. Our results confirmed that the growth temperature and partial pressure of the reactive gas greatly influenced the crystallinity. The optimal growth temperature range was about 460~510℃, and the α-Ga₂O₃ thin films with the highest crystallinity were obtained at a III/VI ratio of 4. The thickness and surface morphology of the thin films was observed by scanning electron microscopy. The film thickness was 6.938 ㎛, and the full width at half maximum of the ω-2θ scan rocking curve was as small as 178 arcsec. The optical band gap energy obtained was 5.21 eV, and the films were almost completely transparent in the near-ultraviolet and visible regions. The etch pit density was found to be as low as about 6.0 × 10⁴ cm^-2.

• Journal of the Korean Vacuum Society
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• v.7 no.s1
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• pp.118-122
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• 1998

$Al_2O_x$(0$Al_2O_3$ gradient coatings were formed by evaporating pure aluminium(99.9%) in $O_2$ environment with an IBAD facility, 12keV $Ar^+$ was used to irradiate the coatings simultaneously during the deposition. Sample's composition and depth profile were analysed by RBS and AES measurement, and their microhardness and porosity property were also measured in the experiment. Results show that, the oxygen concentration in the deposited coatings has a nearly linear relationship with the inputting gas flow before $O_2$ partial pressure in the target chamber reaches $1.2\times10^{-3}$ mbar under which stoichiometric $Al_2O_3$ could be formed; and sample's microhardness and porosity property is affected significantly by the oxygen concentration in the coatings.

• Nuclear Engineering and Technology
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• v.15 no.3
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• pp.197-206
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• 1983

The slightly hyperstoichiometric uranium dioxide, i.e. U $O_{2.005}$ and U $O_{2.01}$ within a range of the requirement for the use of a nuclear fuel, were sintered directly in an atmosphere of $CO_2$/CO mixture without any succeeding reduction process. The kinetics of sintering in the late stage were investigated for various O/U ratios. A sintering diagram, which show the relation of Temperature-Time-Density-Grain size, was established for each O/U ratio. Only by controlling the oxygen partial pressure in the sintering atmosphere, U $O_2$ pellet could be sintered very easily at low temperature 1050$^{\circ}$～120$0^{\circ}C$ with a density above 95% T.D. and average grain size above 7${\mu}{\textrm}{m}$. It was found that the rate of grain growth follows D=(Kt)$^{1}$4/ in the late stage of sintering. And the activation energies for grain growth in the final sintering stage were found to be 75, 64 and 62kca1/mo1 for U $O_{2.005}$, U $O_{2.01}$ and U $O_{2.10}$, respectively. Although no significant differences are obtained between the activation energies for different O/U ratios, the sinterability is enhanced considerably with increasing the oxygen partial pressure in the sintering atmosphere.tmosphere.

• Resources Recycling
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• v.29 no.3
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• pp.3-10
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• 2020

The chlorination kinetics of synthetic rutile prepared by selective chlorination of ilmenite with Cl₂ and CO gas mixture were studied in a fluidized bed. Th e effects of reaction temperature, reaction time, and the ratio of Cl₂ and CO partial pressure ($p_{Cl_2}/p_{CO}$) on the conversion rate of TiCl₄ were investigated. The conversion rate of TiC₄ was low under the high $p_{Cl_2}/p_{CO}$ conditions. Moreover, it was considered that the partial pressure of CO gas was more effective than that of Cl₂ gas when comparing the stoichiometric conversion rate and experimental results of high CO partial pressure. Considering the porous structure of particles, the rate controlling step of the chlorination of synthetic rutile was determined to be chemical reaction and the activation energy was calculated as 53.77 kJ/mol.

• Korean Journal of Materials Research
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• v.13 no.3
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• pp.185-190
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• 2003

Titanium dioxide films were prepared by RF sputtering method on glass for various oxygen partial pressures at power 270 W. The crystal structure, photocatalytic property and the hydrophilicity of $TiO_2$thin film the deposition conditions were investigated. Crystallized anatase phase was observed in $TiO_2$film deposited at the ratio of oxygen partial pressure 10% and 20% for 2 hrs. As the increase of deposition time, the grain size and void size of $TiO_2$film have increased and also $V_2$films have been good crystallinity. The ultraviolet-visible light absorption of $TiO_2$films was increased with increasing of deposition time and occured chiefly at the wavelength between 280 and 340 nm. The absorption band was shifted to a longer wave length as deposition time increased. Water contact angle on the X$TiO_2$film of anatase structure was decreased with increasing ultraviolet illumination time and became lower than $11^{\circ}$ from $83^{\circ}$. When hydrophilic $TiO_2$film changed by enough ultraviolet illumination was stored in the dark, the film surface gradually turned to hydrophobic state.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.118.2-118.2
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• 2017

Combustion behavior of Fe, CuO, NiO, ZnO and $Fe_2O_3$ powder mixture was carried out by finite element method (FEM) to understand a reaction at iron and metal oxide interface. The FEM was done by using ANSYS Fluent 17.0. Initial and boundary conditions are 1 atmosphere, room temperature, 0.1MPa of oxygen partial pressure, $T_{S1}=1127^{\circ}C$, $T_{S2}=327^{\circ}C$ for a cylindrical shape specimen with dia. $35{\times}80$ [mm]. The maximum combustion temperature is $1537^{\circ}C$ for the condition of conduction, convection and radiation. The combustion temperature and rate are about $847^{\circ}C$ and 3.9mm/sec, respectively. The combustion wave is enough to make ternary ferrite phase like $CuNiZnFe_2O_3$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.6
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• pp.518-523
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• 2002

The influences of ion beam energy and reactive oxygen partial pressure on the physical and crystallographic characteristics of transition metal oxide compound(CrOx) film were studied in this paper. Chromium oxide films were deposited onto a cover-glass using ion Beam Sputter Deposition(IBSD) technique according to the various processing parameters. Crystallinity and grain size of as-deposited films were analyzed using XRD analysis. Thickness and Resistivity of the films were measured by $\alpha$-step and 4-point probe measurement. According to the XRD, XPS and resistivity results, the deposited films were the cermet type films which had crystal structure including amorphous oxide(a-oxide) phase and metal Cr phase simultaneously. The increment of the ion beam energy during the deposition process led to decreasing of metal Cr grain size and the rapid change of resistivity above the critical $O_2$ partial pressure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.448-451
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• 2004

Vanadium oxides have been widely used in a variety of technological applications such electrochromic devices as infrared detectors and are expected as a material suitable for gas sensing applications. Thin films of Vanadium oxide (VOx) have been deposited by r.f magnetron sputtering under different oxygen partial pressure ratios and substrate temperatures. Humidity-sensitive properties of resistive sensors having interdigitated electrode structure are characterized. Our sensors show good response to humidity over 20%RH to 80%RH. Vanadium oxide films deposited with 0% $O_2$ partial pressure at foot exhibit greater sensitivity to humidity change than others.