• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.344-344
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• 2011

W(110)면에 흡착원자인 Al원자의 coverage와 annealing과정에서의 온도를 변화시켜, 여러 조건에서의 Al/W(110)계의 흡착구조를 저에너지 전자회절(LEED)과 이온산란분광법(ISS-TOF)을 이용하여 연구하였다. 여러 결과 중, annealing 온도가 900K인 1.0ML Al/W(110)면은 double domain의 p($1{\times}1$)의 흡착구조로 W(110)면의 center of hollow site에서 $0.55{\AA}$ 벗어난 위치에 흡착되었으며, W(110) 표면원자로부터 Al 원자까지의 높이는 $2.13{\pm}0.15{\AA}$이다. 또한 annealing 온도가 1100K인 0.5ML Al/W(110)면은 double domain의 p($2{\times}1$)의 흡착구조로 W(110)면의 center of bridge site에 흡착되었으며, W(110) 표면원자로부터 Al 원자까지의 높이는 $2.18{\pm}0.15{\AA}$이다.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.156.2-156.2
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• 2016

The variation of the surface structure of the Al adsorbed W(110) planes according to the coverage and the substrate temperature has been investigated using LEED and ISS When the Al atoms were adsorbed on the W(110) surface at room temperature, a p($1{\times}1$) of the fcc (111) face were found at the coverage higher than 4 ML. When the substrate temperature was kept at 900 K during Al adsorption and the coverage was 1.0 ML, the surface revealed a p($1{\times}1$) of the bcc(110) face and when the coverage is 1.5 ML, the surface showed a p($1{\times}1$) of the bcc (110) face together with a p($1{\times}1$) double domain structure (fcc (111) face) rotated ${\pm}3^{\circ}$ from the [100] direction of the W(110) surface. When Al atoms were adsorbed on the W(110) surface at the substrate temperature of 1000 K and the coverage was higher than 1.0 ML, the surface revealed a p($1{\times}1$) of the bcc(110) face together with p($1{\times}1$) double domain structure(fcc(111) face) rotated ${\pm}3^{\circ}{\sim}5^{\circ}$ from the [100] direction of the W(110) surface. When Al atoms were adsorbed on the W(110) surface at the substrate temperature of 1100 K and the coverage was 0.5 ML, Al atoms formed a p($2{\times}1$) double domain structure When the coverage was 1.0 ML, the double domain hexagonal structure (fcc(111) face) rotated ${\pm}5^{\circ}$ from the [100] direction of the W(110) surface and another distorted hexagonal structure was found. Low-energy electron diffraction results along with ion scattering spectroscopy results showed that the Al atoms followed the Volmer-Weber growth mode at high temperature.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.185-185
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• 2011

서로 결정구조가 다른 물질 사이의 계면을 연구하기 위해 실온에서 W(bcc) 표면에 Al(fcc)를 성장시켜, 그 흡착구조를 연구하였다. 실온에서 W(110)면에 Al원자를 0.5 ML, 1.0 ML, 2.0 ML, 3.0 ML과 4.0 ML으로 증착시켜 Al/W(110)계의 흡착구조를 저에너지 전자회절(LEED)을 이용하여 관찰하였고, 각 coverage의 Al/W(110)계에서 이온산란분광법(CAICISS-TOF)을 이용하여 흡착구조를 연구하였다. 연구결과, Al의 coverage가 증가함에 따라 표면의 Al이 crystal되어, 4.0 ML Al/W(110)계에서 Al은 6-fold symmetry를 이루는 fcc 구조의 (111)면으로 성장하였으며 성장된 Al(111)면의 [T10]방향과 [1T0]방향이 substrate인 W(110)면의 [001]방향과 서로 평행한 double domain의 표면구조이다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.135-136
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• 2012

Carbon atoms near the surface of W(110) induce reconstructions such as $R(15{\times}12)$ -C/W(110) which consists of two characteristic parts, one square shaped and bright protrusion and two smaller ones. In the atomic resolution STM image, the bigger protrusion shows the periodicities of clean W(110), indicating that it is almost carbon poor region. The smaller protrusion contains hexagonal carbide surface layer of ${\alpha}$-W2C on W(110). Employing this carburized W(110) as templates, we grow Co and Fe clusters of less than ten atoms. Due to the selectivity of bonding sites, growth of larger cluster is highly unfavorable for Co and the size of clusters is very uniform. Since Co atoms prefer to sit on the bigger protrusion rather than smaller one, Co cluster can be arranged one-dimensionally in $R(15{\times}12)$-C/W(110) with quite uniform size distribution. However, Fe clusters sit on both sites without favored site, but still with uniform size distribution. On the other hand, Fe clusters can be grown with quasi one-dimensional order in $R(15{\times}3)$-C/W(110), which consists of only smaller protrusions. We investigate the magnetic properties of the ordered nano-sized clusters. Experiments using XMCD reveals little magnetic moment of Co cluster on $R(15{\times}12)$-C/W(110). This observation is consistent with the predictions of our first principles calculations that small Co clusters can be nonmagnetic or antiferromagnetic with low mean magnetic moment per atom.

• Applied Science and Convergence Technology
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• v.24 no.6
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• pp.228-231
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• 2015

We investigated the adsorption structures and the initial growth mode of ultra-thin Al films on a W(110) surface at a high temperature. When Al atoms were adsorbed on the W(110) at the substrate temperature of 1100 K and with coverage of 0.5ML, Al atoms formed a p($2{\times}1$) double-domain structure. When the coverage was 1.0 ML, the double domain of a hexagonal structure (fcc(111) face) rotated ${\pm}5^{\circ}$ from the [100] direction of the W(110) surface and another distorted hexagonal structure were found. Low-energy electron diffraction results along with ion scattering spectroscopy results showed that the Al atoms followed the Volmer-Weber growth mode at a high temperature.

• Journal of the Korean Vacuum Society
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• v.17 no.5
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• pp.381-386
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• 2008

Adatom kinetics on the surfaces of Co overlayers, prepared on the W(110) surface, was studied with scanning tunneling microscopy. By counting the number-density of the adatom-islands, we estimated the ratio of adatom diffusion coefficients. The ratio $D_{W(110)}:D_{1ML\;Co}:D_{2ML\;Co}$ was measured to be 1 : 125 : 33000 at room temperature, where $D_{W(110)},\;D_{1ML\;Co}$, and $D_{2ML\;Co}$ are the diffusion coefficients on bare W(110) surface, on one-monolayer Co overlayer, and on two-monolayers Co overlayers, respectively. An increased diffusion coefficient on two-ML Co overlayers, relative to that on one-ML Co overlayers, was explained with the heteroepitaxial strain effect.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.06a
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• pp.122-122
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• 1998

• Food Science and Preservation
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• v.24 no.8
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• pp.1129-1137
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• 2017

The fringe tree, Chionanthus retusus (Oleaceae) has been used as a natural remedy that helps a paralytic stroke, dementia, phlegm and malaria. This study was conducted to investigate the antioxidant and anti-aging activities of water extracts obtained from the flesh of C. retusus by reflux extraction at room temperature and $80^{\circ}C$, and pressure heating extraction at $110^{\circ}C$, for an increment of their practical use. The highest extraction yield from the flesh of C. retusus was 67.94% extract by pressure heating extraction at $110^{\circ}C$. The content of total polyphenol compounds was the highest by 72.71 mg/g in $80^{\circ}C$ extract by reflux extraction. The highest content of total flavonoid compounds was 7.60 mg/g at $110^{\circ}C$ extract. The results of soluble protein and reducing sugar contents showed the highest content of 4.93 mg/g and 46.77 mg/g in $110^{\circ}C$ extract, respectively. In the analysis of DPPH radical scavenging activity, all extracts showed an excellent effect of 92% in 1.0 mg/mL concentration. The highest effect of ABTS radical scavenging activity was 88.67% at $110^{\circ}C$ extraction in 1.0 mg/mL concentration. Nitrite scavenging ability was the highest as 66.16% at $110^{\circ}C$ extract at pH 1.2 and 1.0 mg/mL concentration. The results of SOD-like activity and xanthine oxidase inhibition activities showed the highest effect of 14.95% and 59.45% at $110^{\circ}C$ extract in 1.0 mg/mL, respectively. Tyrosinase inhibition activity for whitening effect was the highest of 35.31% at $85^{\circ}C$ in 1.0 mg/mL. In the analysis of anti-aging effect, collagenase and elastase inhibition activity showed the highest effects of 37.78% at $110^{\circ}C$ and 20.39% at $80^{\circ}C$, respectively. All results of antioxidant activities and anti-aging effects increased along with the concentration increases. These results indicated that the extracts extracted from the flesh of C. retusus at $80^{\circ}C$ and $110^{\circ}C$ have a large amount of useful ingredients, an excellent antioxidant activity, like as DPPH and ABTS radical scavenging activity, and anti-aging effects to develop functional products than those of $25^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.82-82
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• 2010

metal/metal계에서는 표면 원자의 재결합이 이루어 져서 표면의 특성이 bulk와는 전혀 다른 물리 화학적 특성을 보인다. 본 연구에서는 텅스텐 (110)면에 알루미늄 원자를 흡착시켜 저에너지 전자회절(LEED)과 이온산란분광법(ISS-TOF)을 이용하여 표면구조를 연구하였다. 텅스텐 (110)면 표면을 1000 K로 가열하는 동안 알루미늄을 1.0 ML 흡착시켰다. 이 때 p($1{\times}1$) LEED 이미지가 관측되었다. Al/W(110)계면에서 알루미늄 원자가 텅스텐 표면원자와의 결합거리와 방향 등 흡착위치를 알아보기 위해 이온산란분광법을 이용하였다. 그 결과 알루미늄 원자는 double domain으로 W(110) 표면의 hollow site에서 $0.55\;{\AA}$ 벗어나 위치하였으며, 텅스텐의 첫 번째 원자 층으로부터의 높이는 $2.13{\pm}0.1\;{\AA}$이다. 알루미늄 원자와 가장 가까운 텅스텐 원자까지의 거리는 $2.71{\pm}0.15\;{\AA}$이다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.3
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• pp.465-472
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• 1997

An extension of new test methods for surfaces with an apparatus based on photon-induced desorption and ionisation in the electric field, is constructed and tested, It also investigates how to show the efficiency of the arrangement adsorbates $H_2$ and He on W(110). The field emitter temperature was 80 K. The wavelength of light used was 193 nm with field strengths between 10 and 50 V/nm. Many ion fragments($CO^+, He^+, H_2^^+, H_2O^+, W^{3+}\; and\; W^{2+}$) were produced by an electronic stimulation of the adsorbate with the help of a photon energy of 6.4 eV at He and $H_2$/W(110). A transient recorder enables the registration of the entire mass spectrum.