• The Korean Journal of Physiology
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• 제26권2호
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• pp.123-128
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• 1992

The present study was undertaken to examine if endogenous nitric oxide is partly responsible for the high calcium induced vasorelaxation in vitro. Isolated porcine coronary arterial rings were suspended in the tissue chamber and their changes in isometric tension were recorded. KCI little affected the vascular tension in the calcium free media, but subsequent addition of cumulative doses of $CaCl_3$ from 1 to 40 mM caused a contraction followed by complete relaxation. The maximum tension was noted at the calcium concentration in the media of 5 mM, and then the tension progressively declined at 10-40 mM. The relaxation was slightly attenuated in the endothelium-denuded preparation. The relaxation was converted into a contraction by the addition of methylene blue. The relaxation response was not affected in the presence of indomethacin, but was significantly attenuated by $N^w-nitro-L-arginine$ methyl ester pretreatment. These results suggest that the calcium induced vasorelaxation is in part attributable to the release of endogenous nitric oxide.

• 통합자연과학논문집
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• 제12권4호
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• pp.116-121
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• 2019

This experiment is to evaluate the physical properties of the hydrogel lens with the addition of carbon-based nanomaterials, Graphene oxide and Carbon nanotube, and to confirm the improvement of strength. Hyaluronic acid, a hydrophilic substance, was used as an additive by using HEMA (2-hydroxyethyl methacrylate) and ethylene glycol dimethacrylate (EGDMA) as a base monomers. Graphene oxide and two types of Carbon nanotubes(Amide functionalized and Carboxilic acid functionalized) were added 0.1%, 0.3%, 0.5%, respectively, and the physical properties were analyzed by measuring water content, refractive index, breaking strength and SEM image. In the case of the sample added with each carbon nano material, the water content tended to increase for all three materials. The breaking strength tended to increase in Graphene oxide and Carbon nanotube; Carboxilic acid functionalized, but in the case of Carbon nanotube; amide fuctionalized, the breaking strength tended to decrease. However, Carbon nanotube; amide fuctionalized had the highest breaking strength among the three nano materials. Thus, the addition of certain carbon nanomaterials seems to be appropriate for improving the strength of hydrogel lenses.

• 대한화학회지
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• 제23권3호
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• pp.152-160
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• 1979

Furfural의 수소화반응에 쓰이는 구리-크롬산화물계 촉매에서 바륨, 스트론륨 등의 첨가효과 및 그 기능에 관하여 조사하였다. X-선 회절에 의하면 $BaCrO_4$, $SrCrO_4$등의 생성을 확인할 수 있었으나, 촉매표면적에는 차이가 없었다. 그러나 이들의 첨가로 촉매능은 개선되어 첨가전보다 반응시간에 따른 활성저하폭이 훨씬 적어졌다. 바륨이 첨가된 또는 실기카에 분산시킨 촉매는 CO흡착으로 분산된 Cr(V)의 EPR 스펙트럼을 보여주었으며 표면의 산화-혼원과정에서 가역적인 스펙트럼을 나타내었다. 바륨의 첨가로 촉매활성점이 분산되어 존재함으로서 furfural의 수소화반응에서 향상된 촉매능을 보여주는 것으로 생각된다.

• 한국재료학회지
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• 제25권8호
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• pp.376-385
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• 2015

The effects of Nb and Cr addition on the microstructure, corrosion and oxide characteristics of Zr based alloys were investigated. The corrosion tests were performed in a pressurized water reactor simulated-loop system at $360^{\circ}C$. The microstructures were examined using OM and TEM, and the oxide properties were characterized by low-angle X-ray diffraction and TEM. The corrosion test results up to 360 days revealed that the corrosion rates were considerably affected by Cr content but not Nb content. The corrosion resistance of the Zr-xNb-0.1Sn-yCr quaternary alloys was improved by an increasing Nb/Cr ratio. The crystal structure of the precipitates was affected by a variation of the Nb/Cr ratio. The Zr-Nb beta-enriched precipitates were mainly formed in the high Nb/Cr ratio alloy while $Zr(NbCr)_2$ precipitates were frequently observed in the low Nb/Cr ratio alloy. The studies of oxide characteristics revealed that the corrosion resistance was related to the crystal structure of the precipitate.

• 한국재료학회지
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• 제16권11호
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• pp.687-691
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• 2006

Synthesis of Iron oxides by air oxidation of $FeSO_4$ solutions in the presence of NaOH, Diethylenetriamine (DETA), Butylamine (BA) and influence of ultrasonic wave were investigated by XRD, SEM and particle size analyzer. As the DETA addition increased to 0.05 mol, $Fe_3O_4$ was formed with goethite($\alpha$- FeOOH) and $Fe_3O_4$ single phase was formed above 0.18mol of DETA. As the BA addition increased, the XRD peak intensity of (020) face of lepidocrocite($\gamma$-FeOOH) was developed until the formation of $Fe_3O_4$ and reduced the size of the iron oxide particles formed. Ultrasonic wave reduced the size of the iron oxide particles but gave little effects on the iron oxide particles synthesized by amine.

• 한국결정성장학회지
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• 제8권3호
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• pp.424-430
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• 1998

MONOS(metal-oxide-nitride-oxide-semicondutor) EEPROM에 응용하기 위한 얇은 ONO 유전층의 막 특성을 AES, SIMS, TEM 및 AFM을 이용하여 조사하였다. 터널링 산화막, 질화막, 블로킹 산화막의 두께를 각각 달리하여 ONO 박막을 제작하였다. 터널링 산화막 위에 LPCVD방법으로 질화막을 증착하는 동안 얇은 터널링 산화막이 질화되었으며, 질화막 위에 블로킹 산화막을 형성할 때, 산소가 질화막 표면을 산화시킬 뿐만 아니라 질화막을 지나 확산되었다. ONO 박막은 $SiO_2$(블로킹 산화막)/O-rich SiOxNy(계면)/N-rich iOxNy(질화막)/O-rich SiOxNy(터널링 산화막)으로 이루어졌다. SiON상은 주로 터널링 산화막과 질화막, 질화막과 블로킹 산화막 계면에 분포하였으며, $Si_2NO$상은 각 계면의 질화막 쪽과 터널링 산화막 내에 분포하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.185.2-185.2
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• 2015

Tin Oxide (SnO2) has been widely investigated as a transparent conducting oxide (TCO) and can be used in optoelectronic devices such as solar cell and flat-panel displays. In addition, it would be applicable to fabricating the wide bandgap semiconductor because of its bandgap of 3.6 eV. There have been concentrated on the improvement of optical properties, such as conductivity and transparency, by doping Indium Oxide and Gallium Oxide. Recently, with development of fabrication techniques, high-qulaity SnO2 epitaxial thin films have been studied and received much attention to produce the electronic devices such as sensor and light-emitting diode. In this study, powder sputtering method was employed to deposit epitaxial thin films on sapphire (0001) substrates. A commercial SnO2 powder was sputtered. The samples were prepared with varying the growth parameters such as gas environment and film thickness. Then, the samples were characterized by using XRD, SEM, AFM, and Raman spectroscopy measurements. The details of physical properties of epitaxial SnO2 thin films will be presented.

• 대한의용생체공학회:의공학회지
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• 제14권4호
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• pp.333-340
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• 1993

The high biocompatibility of titanium is connected with the high corrosion resistance of the surface oxide, its high dielectric constant, and some other specific biochemical properties of the oxide. The corrosion resistance of titanium can be improved with the formation of passive film by anodic oxidation. In other to characterize the titantium oxlde film formed by anodic oxidation, titanium plates were anodized in 0.5M $H_3SO_4$ electrolyte at voltages between 5V and 100v. The oxide film was examined by an X-Ray Diffractometer(XRD) and a Scanning Electron Microscope(SEM). In addition, the corrosion resistance of oxide film was tested by dipping in physiological NaCl,5% HCI,5% $H_3PO_4$ and its biocompatability was evaluated by the fibroblast-like cell culture. The results obtained are as follows : 1. The thickness of surface oxide and micropore are increased with the increase of electrode potential and formed deeply along the grain boundary. 2. The solubilities of titanium in electrolyte solution shows that the anodized titanium has more corrosion resistance than the untreated pure titanium. 3. The biocomatibility of anodized titanium is superior to untreated pure titanium.

• JSTS:Journal of Semiconductor Technology and Science
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• 제12권1호
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• pp.41-45
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• 2012

We observed that in chemical vapor deposition (CVD) tungsten silicide (WSix) poly gate scheme, the gate oxide thickness decreases as gate length is reduced, and it intensifies the roll-off properties of transistor. This is because the fluorine diffuses laterally from WSix to the gate sidewall oxide in addition to its vertical diffusion to the gate oxide during gate re-oxidation process. When the channel length is very small, the gate oxide thickness is further reduced due to a relative increase of the lateral diffusion than the vertical diffusion. In DRAM cells where the channel length is extremely small, we found the thinned gate oxide is a main cause of poor retention time.

• 한국주조공학회지
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• 제10권2호
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• pp.154-161
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• 1990

The microstructures of sintered products of $Fe_2O_3$or $Fe_3O_4$-Oxide added cast iron powder was investigated. And the effects of particle size distribution was investigated too. As the result, the structures of sintered products did not related to the species of Fe-Oxide. Th porosity of sintered products was decreased in size and spherodized with increasing sintering temperature, decreasing Fe-Oxide quantity. Fe-Oxide itself did not hinder sintering of cast iron powder particularly, therefore sintering could be occurred without termination of reduction of it. And the sintered products of finer particle size distribution had finer and more spherodized porosity, and had minimized the deviation of size and shape of porosity.