• Clinical and Experimental Pediatrics
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• 제54권9호
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• pp.359-362
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• 2011

There is a delicate balance between too little and too much supplemental oxygen exposure in premature infants. Since underuse and overuse of supplemental oxygen can harm premature infants, oxygen saturation levels must be monitored and kept at less than 95% to prevent reactive oxygen species-related diseases, such as retinopathy of prematurity and bronchopulmonary dysplasia. At the same time, desaturation below 80 to 85% must be avoided to prevent adverse consequences, such as cerebral palsy. It is still unclear what range of oxygen saturation is appropriate for premature infants; however, until the results of further studies are available, a reasonable target for pulse oxygen saturation ($SpO_2$) is 90 to 93% with an intermittent review of the correlation between $SpO_2$ and the partial pressure of arterial oxygen tension ($PaO_2$). Because optimal oxygenation depends on individuals at the bedside making ongoing adjustments, each unit must define an optimal target range and set alarm limits according to their own equipment or conditions. All staff must be aware of these values and adjust the concentration of supplemental oxygen frequently.

• 한국정보통신학회논문지
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• 제22권4호
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• pp.664-669
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• 2018

본 연구는 투명산화물반도체의 전기적인 특성과 산소공공과의 관계를 알아보기 위해서 $TiO_2$ 박막을 증착하여 MIM 구조를 만들어서 전압전류 특성을 관찰하였다. 산소공공은 XPS분석으로 이루어졌으며, 커패시턴스를 측정하여 전하의 용량이 많은 곳에서 산소공공이 어떤 영향을 주는가에 대하여도 조사하였다. 열처리를 통하여 결정질구조로 변하는 $TiO_2$ 박막은 산소공공이 가장 낮은 곳에서 커패시턴스 값이 가장 높았으며, 전하의 양이 많았다. 따라서 전하의 양이 많은 $TiO_2$박막이 $CO_2$ 가스에 대하여 가장 잘 민감하게 반응하는 것을 확인하였다.

• 한국세라믹학회지
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• 제28권12호
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• pp.989-995
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• 1991

By means of the secondary ion mass spectrometer, the tracer diffusion of oxygen in rutile single crystal was measured as function of temperature and oxygen partial pressure. The tracer diffusivity was determined from the depth profile of 18O. The Po2 dependence of D suggests that the dominant defects in TiO2-y are oxygen vacancies (V{{{{ { ‥} atop { o} }}) and interstitial titanium ions (Ti{{{{ {‥‥} atop {i} }}). The doubly ionized oxygen vacancies are prominent at low temperature and Po2. However, the tetravalent interstitial titanium ions predominate at teperature above 120$0^{\circ}C$.

• 공업화학
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• 제31권4호
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• pp.368-376
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• 2020

본 연구에서는 SO₂를 제어하기 위한 산화 촉매에서 platinum (Pt)을 활성금속으로 하는 촉매의 반응특성에 관한 분석을 수행하였다. Titania (TiO₂) 지지체에 다양한 precursor 형태의 Pt를 사용하여 Pt/TiO₂ 촉매를 제조하여 실험에 사용하였다. Pt/TiO₂ 상의 Pt²⁺ 또는 Pt⁴⁺와 같은 Pt valence state에 따른 SO₂ 산화의 성능 차이는 나타나지 않으며, PtCl_x과 같은 Pt chloride species는 전체적으로 SO₂ 산화 성능을 감소시킨다. 또한, XPS 분석을 수행하여 SO₂ 산화 반응 전/후의 촉매상의 valence state를 분석한 결과 SO₂ 산화반응 이후 lattice oxygen의 감소 및 surface chemisorbed oxygen의 증가를 확인할 수 있다. 따라서 Pt/TiO₂ 촉매의 SO₂의 산화 반응은 PtOx에 해당하는 lattice oxygen의 반응과 oxygen vacancy에 의한 산화-환원 반응이 진행되는 Mar-Van Krevelen 메커니즘이 주요한 SO₂ 산화 반응임을 판단할 수 있으며, 이러한 결과를 통하여 촉매 상에 존재하는 PtOx (Pt²⁺ 또는 Pt⁴⁺)의 oxygen species가 주요한 활성 site로 작용함을 확인할 수 있다.

• The Korean Journal of Ceramics
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• 제4권2호
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• pp.78-82
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• 1998

The oxygen nonstoichiometry (x) of UO$_{2+x}$ and $(Ce_yU_{1-y})O_{2+x}$ (y=0.05, 0.25) has been measured as a function of oxygen activity (a02) at 100$0^{\circ}C$ by a solid state coulometri titration technique. The results for UO$_{2+x}$ are in a good agreement with literature data and the ao2-dependence of the nonstoichimetry has been well explained with (2:2:2) cluster model. The equilibrium oxygen activity of $(Ce_yU_{1-y})O_{2+x}$ increases with Ce-content (y) for given nonstoichiometry (x), which is ascribed to the fact that Ce is present as Ce$^{3+}\; and\; Ce^{4+}$, and, therefore, the addition of Ce reduces the oxidation capacity of UO$_{2+x}$. From the oxygen activity dependence of x in $(Ce_yU_{1-y})O_{2+x}$ the defect structure of $(Ce_yU_{1-y})O_{2+x}$ is discussed.

• 한국대기환경학회지
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• 제30권6호
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• pp.577-585
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• 2014

A series of experiments using atmospheric-pressure non-thermal plasma coupled with transition metal catalysts were performed to remove ethylene from agricultural storage facilities. The non-thermal plasma was created by dielectric barrier discharge, which was in direct contact with the catalyst pellets. The transition metals such as Ag and $V_2O_5$ were supported on ${\gamma}-Al_2O_3$. The effect of catalyst type, specific input energy (SIE) and oxygen content on the removal of ethylene was examined to understand the behavior of the hybrid plasma-catalytic reactor system. With the other parameters kept constant, the plasma-catalytic activity for the removal of ethylene was in order of $V_2O_5/{\gamma}-Al_2O_3$ > $Ag/{\gamma}-Al_2O_3$ > ${\gamma}-Al_2O_3$ from high to low. Interestingly, the rate of plasma-catalytic ozone generation was in order of $V_2O_5/{\gamma}-Al_2O_3$ > ${\gamma}-Al_2O_3$ > $Ag/{\gamma}-Al_2O_3$, implying that the catalyst activation mechanisms by plasma are different for different catalysts. The results obtained by varying the oxygen content indicated that nitrogen-derived reactive species dominated the removal of ethylene under oxygen-lean condition, while ozone and oxygen atoms were mainly involved in the removal under oxygen-rich condition. When the plasma was coupled with $V_2O_5/{\gamma}-Al_2O_3$, nearly complete removal of ethylene was achieved at oxygen contents higher than 5% by volume (inlet ethylene: 250 ppm; gas flow rate: $1.0Lmin^{-1}$; SIE: ${\sim}355JL^{-1}$).

• 청정기술
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• 제27권1호
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• pp.9-16
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• 2021

Active Matrix Organic Light-Emitting Diode (AMOLED) 봉지 공정은 수분과 산소에 매우 취약하기 때문에, 수분과 산소의 함량이 최소화된 고순도의 질소를 사용하여야 한다. 본 연구의 목적은 AMOLED 봉지 공정에 사용하는 질소에서 산소를 제거하기 위한 용도로 사용되는 구리계 촉매를 최적화하는 것이다. CuO, Al2O3, 또는 ZnO의 조성으로 이루어진 2성분계 및 3성분계 촉매를 공침법을 통해서 제조하였다. 제조된 촉매들을 BET, XRD, TPR, XRF의 분석장비를 활용하여 촉매의 특성을 분석하였다. 촉매의 산소 제거 성능을 확인하기 위해 고정층 반응기에서 촉매 산소 제거 반응 실험을 수행하고 산소 분석기를 통해 산소 함량을 측정하였다. 또한 사용된 촉매의 반복 재생을 통해 촉매의 재사용 성능을 검증하였다. CuO와 Al2O3 비율이 6 : 4, 7 : 3 및 8:2로 제조된 2 성분계 촉매의 특성과 산소 제거 능력을 비교하였다. CuO와 Al2O3의 비율이 8:2인 촉매의 환원성이 가장 높았는데, 이는 CuO의 분산도가 가장 높기 때문이다. 결과적으로, 2성분계 촉매 중에서 CuO와 Al2O3의 비율이 8 : 2 인 촉매의 산소 제거 능력이 가장 우수한 것으로 나타났다. CuO : Al2O3 의 비율이 8:2인 촉매에 ZnO를 2 wt% 넣어준 촉매가 3성분계 촉매 중에는 가장 우수한 산소제거 능력을 보였으며, 이는 뛰어난 환원성에 기인한다고 할 수 있다. 또한 이 촉매는 재생 실험을 통해서도 산소 제거능력이 유지된다는 것을 확인하였다.

• 한국수소및신에너지학회논문집
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• 제34권5호
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• pp.535-548
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• 2023

The intermittent nature of renewable energy is a challenge to overcome for safety and stable performance in water electrolysis systems linked to renewable energy. Oxygen removal using the catalyst is suitable for maintaining the oxygen concentration in hydrogen below the explosive level (4%) even in intermittent power supply. Metals such as Pd, Pt, and Ni are expected to be effective materials due to their hydrogen affinity. The oxygen removal performance was compared under high hydrogen concentration conditions by loading on γ-Al₂O₃ with high reactivity and large surface area. The characteristics of the catalyst before and after the reaction were analyzed through X-ray diffraction, transmission electron microscope, H₂-temperature programmed reduction, X-ray photoelectron spectroscope, etc. The Pd catalyst that showed the best performance was able to lower 2% oxygen to less than 5 ppm. Changes in catalyst characteristics after the reaction indicate that oxygen vacancies are related to oxygen removal performance and catalyst deactivation.

• Transactions on Electrical and Electronic Materials
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• 제3권2호
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• pp.24-27
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• 2002

The NdBaCuO superconductor samples were zone-melted in low oxygen partial pressure (1%O$_2$+99%Ar). The zone-melting temperature was decreased about 12$0^{\circ}C$ film 1,06$0^{\circ}C$, the zone-melting temperature in air. Thus the loss of liquid phase (BaCuO$_2$ and CuO) was reduced during: the zone-melting process. The content of non-superconducting phase Nd422 in zone-melted NdBaCuO samples was clearly decreased and, therefore, the substitution of Nd for Ba was occurred. The superconductivity of zone-melted Nd$_{1+x}$Ba$_{2-x}$Cu$_3$O$_{y}$ prepared under low oxygen partial pressure was distinctively improved.d.d.d.

• 센서학회지
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• 제13권3호
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• pp.252-257
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• 2004

$Y_{2}O_{3}:Eu^{3+}$ thin films have been grown on $Al_{2}O_{3}$(0001) substrates by a pulsed laser deposition (PLD) method. The phosphor thin films were deposited at a substrate temperature of 500, 600, and $700^{\circ}C$ under the oxygen pressure of 100, 200, and 300 mTorr. The crystallinity, surface roughness and photoluminescence of the films are highly dependent on the substrate temperature and oxygen pressure. The films grown on $Al_{2}O_{3}$(0001) substrate even under the different substrate temperatures and oxygen pressures exhibited (222) preferred orientation. The luminescent spectra exhibited strong luminescence of ${^{5}D_{0}}-{^{7}F_{2}}$ transition within $Eu^{+3}$ peaking at 612 nm. The crystallinity and luminescence intensity of the films have been improved as the substrate temperature increasing. With increase of oxygen pressure from 50 to 300 mTorr, the crystallinity of the films has been uniformly decreased. The photoluminescence intensity and surface roughness have similar behaviors as a function of oxygen pressure. At 200 mTorr, both photoluminescence intensity and surface roughness show a maximum.