• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.198-198
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• 2013

Metal-Oxide-Semiconductor (MOS)에서 사용되는 다양한 channel materials로 high electron mobility을 가지는 III-V compound semiconductor가 대두되고 있다 [1,2]. 하지만 이러한 III-V compound semiconductor는 Si에 비해 안정적인 native oxide가 부족하기 때문에 Si, Ge, Al2O3과 BeO 등과 같은 다양한 물질들의 interface passivation layers (IPLs)에 대한 연구가 많이 되고 있다. 이러한 IPLs 물질은 0.5~1.0 nm의 매우 얇은 physical thickness를 가지고 있고 또한 chemical inert하기 때문에 플라즈마 식각에 대한 연구가 되고 있지만 IPLs 식각 후 기판인 III-V compound semiconductor에 physical damage과 substrate recess를 줄이기 위해서 높은 선택비가 필요하다. 이러한 식각의 대안으로 원자층 식각이 연구되고 있으며 이러한 원자층 식각은 반응성 있는 BCl3의 adsorption과 low energy의 Ar bombardment로 desorption으로 self-limited한 one monolayer 식각을 가능하게 한다. 그러므로 본 연구에서는, III-V compound semiconductor 위에 IPLs의 adsorption과 desorption의 cyclic process를 이용한 원자층식각으로 다양한 물질인 SiO2, Al2O3 (self-limited one monolayer etch rate=about 1 ${\AA}$/cycle), BeO (self-limited one monolayer etch rate=about 0.75 ${\AA}$/cycle)를 얻었으며 그 결과 precise한 etch depth control로 minimal substrate recess 식각을 할 수 있었다.

• 한국식품과학회지
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• 제23권2호
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• pp.175-182
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• 1991

옥수수 전분을 propylene oxide와 반응시켜 치환도가 $0.031{\sim}0.147$되는 hydroxypropyl 옥수수 전분을 제조하여 물리화학적 특성을 규명하였다. Hydroxypropylation에 의하여 팽윤력, 용해도 및 물결합 능력이 증가하고 생전분의 효소 분해력이 높아졌으며 요오드 흡착강도가 낮아졌다. 아울러 hydroxypropylation에 의하여 전분의 결정화도도 감소되었다. 한편, 옥수수 전분을 hydroxypropylation시켰을 때 분자량 $1.34{\times}10^7$ 이상의 큰 분자는 감소하였고 $1.34{\times}10^7{\sim}1.18{\times}10^5$의 전분 분자는 증가하였다. Hydroxypropylation에 의하여 옥수수 전분 입자의 형태에는 별 변화가 없었으나 입자크기는 평균입경이 $13.9\;{\mu}m$에서 $16.0\;{\mu}m$로 증가하였다.

• Natural Product Sciences
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• 제28권3호
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• pp.153-160
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• 2022

Neuroinflammation is known to be associated with brain injury in Alzheimer's disease (AD), and the inhibition of microglial activation, a key player in inflammatory response, is considerd as important target for AD. In this study, the ethanol extract of aerial parts of Forsythia velutina Nakai, a Korean native species, significantly inhibited nitric oxide (NO) production in LPS-stimulated BV2 microglial cells. Thus, the active principles in F. velutina aerial parts were isolated based on activity-guided isolation method. As a result, six compounds were isolated and their structures were elucidated based on NMR data and the comparison with the relevant references as arctigenin (1), matairesinol (2), rengyolone (3), ursolic acid (4), secoisolariciresinol (5), and arctiin (6). Among them, four compounds including arctigenin (1), matairesinol (2), secoisolariciresinol (5), and arctiin (6) significantly inhibited NO production in a dose-dependent manner. In particular, matairesinol (2) and secoisolariciresinol (5) reduced 60% of NO production compared to LPS-treated group. This inhibitory effects of matairesinol (2) and secoisolariciresinol (5) were accompanied with the reduced expression levels of iNOS and COX-2. These results suggest that the extract of F. velutina and its active compounds could be beneficial for neuroinflammatory diseases including AD.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.93-94
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• 2022

The presence of chloride (Cl-) ions in environments causes localized corrosion resulting decrease the durability of the structures. In this study, 5% Mg containing Al alloys (Al-5Mg) wire used vis-à-vis compared its corrosion resistance with pure Al in 3.5wt.% NaCl solution with exposure periods. Initially both wires exhibited identical open circuit potential (OCP) attributed to the presence of native oxide film on the surface but with the exposure periods it shifted towards active direction owing to the dissolution of oxide film. The pure Al continuously shifted the OCP towards active direction while Al-5Mg shows stabilization of OCP after 8 days of exposure. The OCP of Al-5Mg is slightly higher compared to pure Al wire owing to the activeness of Mg. The total impedance of the Al-5Mg alloy is almost three times greater than pure Al with exposure periods in 3.5 wt.% NaCl solution. It might be formation of Al-Mg LDH (layered double hydroxide) thin film onto the surface.

• 한국수소및신에너지학회논문집
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• 제22권3호
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• pp.283-291
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• 2011

Polymer electrolyte membrane fuel cells (PEMFCs) use the bipolar plate of various materials between electrolyte and contact electrode for the stable hydrogen ion exchange activation. The bipolar plate of various materials has representatively graphite and stainless steel. Specially, stainless steels have advantage for low cost and high product rate. In this study, SUS 316 was effectively coated with 600 nm thick F-doped tin oxide (SnOx:F) by electron cyclotron resonance-metal organic chemical vapor deposition and investigated in simulated fuel cell bipolar plates. The results showed that an F-doped tin oxide (SnOx:F) coating enhanced the corrosion resistance of the alloys in fuel cell bipolar plates, though the substrate steel has a significant influence on the behavior of the coating. Coating SUS 316 for fuel cell bipolar plates steel further improved the already excellent corrosion resistance of this material. After coating, the increased ICR values of the coated steels compared to those of the fresh steels. The SnOx:F coating seems to add an additional resistance to the native air-formed film on these stainless steels.

• E2M - 전기 전자와 첨단 소재
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• 제16권9호
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• pp.64.2-65
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• 2003

A 4 nm layer of ZrOx (targeted x-2) was deposited on an interfacial layer(IL) of native oxide (SiO, t∼1.2 nm) surface on 200 mm Si wafers by a manufacturable atomic layer chemical vapor deposition technique at 30$0^{\circ}C$. Some as-deposited layers were subjected to a post-deposition, rapid thermal annealing at $700^{\circ}C$ for 5 min in flowing oxygen at atmospheric pressure. The experimental x-ray diffraction, x-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and high-resolution parallel electron energy loss spectroscopy results showed that a multiphase and heterogeneous structure evolved, which we call the Zr-O/IL/Si stack. The as-deposited Zr-O layer was amorphous $ZrO_2$-rich Zr silicate containing about 15% by volume of embedded $ZrO_2$ nanocrystals, which transformed to a glass nanoceramic (with over 90% by volume of predominantly tetragonal-$ZrO_2$(t-$ZrO_2$) and monoclinic-$ZrO_2$(m-$ZrO_2$) nanocrystals) upon annealing. The formation of disordered amorphous regions within some of the nanocrystals, as well as crystalline regions with defects, probably gave rise to lattice strains and deformations. The interfacial layer (IL) was partitioned into an upper Si $o_2$-rich Zr silicate and the lower $SiO_{x}$. The latter was sub-toichiometric and the average oxidation state increased from Si0.86$^{＋}$ in $SiO_{0.43}$ (as-deposited) to Si1.32$^{＋}$ in $SiO_{0.66}$ (annealed). This high oxygen deficiency in $SiO_{x}$ indicative of the low mobility of oxidizing specie in the Zr-O layer. The stacks were characterized for their dielectric properties in the Pt/{Zr-O/IL}/Si metal oxide-semiconductor capacitor(MOSCAP) configuration. The measured equivalent oxide thickness (EOT) was not consistent with the calculated EOT using a bilayer model of $ZrO_2$ and $SiO_2$, and the capacitance in accumulation (and therefore, EOT and kZr-O) was frequency dispersive, trends well documented in literature. This behavior is qualitatively explained in terms of the multi-layer nanostructure and nanochemistry that evolves.ves.ves.

• 한국식품과학회지
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• 제31권4호
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• pp.999-1004
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• 1999

밤에서 추출한 천연 밤전분(NCS)과 이에 propylene oxide를 반응시켜 제조한 hydroxypro-pyl화 밤전분(HCS)의 이화학적 특성을 비교 검토하였다. 색도는 NCS와 HCS 사이에 별 차이가 없었고, 물결합 능력은 NCS가 233.8%, HCS가 244.5%를 나타내어 HCS의 물결합 능력이 증가하는 양상을 보였다. Hydroxypropylation에 의해 HCS의 청가 및 amylose 함량이 다소 감소하여 전분의 구조가 변형됨을 알 수 있었고 팽화력과 용해도에서도 증가하였다. 0.2% 전분 현탁액으로 광투과도를 측정한 결과 역시 HCS가 NCS에 비해 증가함을 알 수 있었다. DSC와 amylogram을 이용하여 호화 양상을 측정한 결과 hydroxypropylation에 의해 HCS의 호화 온도 및 호화 엔탈피가 감소하여 HCS를 식품가공에 이용할 경우 전분이 호화되는데 필요한 열량이 감소하여 경제적인 잇점이 있을 것으로 생각된다.

• 한국세라믹학회지
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• 제38권8호
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• pp.740-748
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• 2001

출발원료 Si 분말의 입자크기를 다양하게 하여 질화반응 및 가스압 소결시 입자크기에 따른 산소함량의 차이에서 나타나는 상변화와 그로 인한 치밀화 거동, 미세구조 발달 및 기계적 특성에 대하여 고찰하였다. 145$0^{\circ}C$의 질화반응에서는 조대분말을 사용한 경우가 미세분말을 사용한 경우보다 높은 질화율을 나타냈으며, 각 분말크기에 따른 native oxide의 함량차에 따라 각기 다른 2차 결정상들이 검출되었다. 조대분말을 사용한 경우에는 제 2상의 석출로 인한 액상량의 부족으로 고온의 소결온도에서도 치밀화를 이루지 못해 낮은 강도값을 나타내었다. 한편, 미세분말을 사용한 경우에는 질화반응 후 석출된 제 2상이 소결온도가 증가함에 따라 용융되면서 치밀화를 이루어 높은 강도값을 나타내었다. 높은 강도값은 미세분말을 사용한 시편들에서 얻어졌으나 높은 파괴인성값은 상대적으로 큰 분말을 사용한 시편들에서 얻어졌는데, 이는 미세한 입자들로 구성된 기지상 내에 잘 발달된 주상정 입자들을 갖는 미세구조에 기인된 것으로 사료된다.

• 대한본초학회지
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• 제26권2호
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• pp.67-73
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• 2011

Objectives : The purpose of this research was total polyphenol contents, anti-oxidant activities, anti-inflammatory activities and anti-wrinkle activities of Ulleung islands plants for application as a cosmeceutical ingredients Methods : We were experimented total polyphenol contents, anti-oxidant activities, anti-inflammatory activity and anti-wrinkle activities. Results : In the physiological activities, most Ulleung islands plants is showed the highest anti-oxidant, anti-inflammatory activity in ABTS+ radical cation scavenging activity, hydrogen peroxide($H_2O_2$) scavenging activity, nitric oxide scavenging activity. All experiment of the water and ethanol extract from the Ulleung islands plants ingredients were gradually increased as well. Conclusions : These results suggest that extracts from Ulleung islands plants can be used in natural ingredient in food or cosmetic industry.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 제35회 춘계학술대회
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• pp.40-44
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• 2002

The motivation of this work is to use SAM(Self-Assembled Monolayer) for developing a rapid and flexible non-photolithographic nano-structure fabrication technique which can be utilized in micro-machining of metals as well as silicon-based materials. The fabrication technique implemented in this work consists of a two-step process, namely, mechanical scribing followed by chemical etching. From the experimental results, it was found that thiol on copper surface could be removed even under a few nN normal load. The nano-tribological characteristics of thiol-SAM on various metals were largely dependent on the native oxide layer of metals. Based on these findings, nano-patterns with sub-micrometer width and depth on metal surfaces such as Cu, Au and Ag could be obtained using a diamond-coated tip.