• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.255-255
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• 2016

Resistive random access memory (ReRAM)는 낮은 동작 전압, 빠른 동작 속도, 고집적화 등의 장점으로 인해 차세대 비휘발성 메모리 소자로써 많은 관심을 받고 있다. 최근에 ReRAM 절연막으로 NiOx, TiOx, AlOx TaOx, HfOx와 같은 binary metal oxide 물질들을 적용하는 연구가 활발히 진행되고 있다. 특히, HfOx는 안정적인 동작 특성을 나타낸다는 점에서 ReRAM 절연막 물질로 적합하다고 보고되고 있다. ReRAM 절연막을 형성할 때, 물리 기상 증착 방법 (PVD)이나 화학 기상 증착법 (CVD)과 같은 방법이 많이 이용된다. 이러한 증착 방법들은 고품질의 박막을 형성시킬 수 있는 장점이 있다. 하지만, 높은 온도에서의 공정과 고가의 진공 장비가 이용되기 때문에 경제적인 문제가 있으며, 기판 또는 금속에 플라즈마 손상으로 인한 문제가 발생할 수 있다. 따라서 이러한 문제점들을 개선하기 위해 용액 공정이 많은 관심을 받고 있다. 용액 공정은 공정과정이 간단할 뿐만 아니라 소자의 대면적화가 가능하고 공정온도가 낮으며 고가의 진공장비가 필요하지 않은 장점을 가진다. 따라서 본 연구에서는, 용액공정을 이용하여 HfOx 기반의 ReRAM 제작하였고 $25^{\circ}C$와 $85^{\circ}C$에서 ReRAM의 동작특성에 미치는 compliance current의 영향을 평가하였다. 실험 방법으로는, hafnium chloride (0.1 M)를 2-methoxyethanol에 충분히 용해시켜서 precursor를 제작하였다. 이후, p-type Si 기판 위에 습식산화를 통하여 300 nm 두께의 SiO2 절연층을 성장시킨 후, 하부전극을 형성하기 위해 electron beam evaporation을 이용하여 10/100 nm 두께의 Ti/Pt 전극을 증착하였다. 순차적으로, 제작된 산화물 precursor를 이용하여 Pt 위에 spin coating 방법으로 1000 rpm 10 초, 6000 rpm 30초의 조건으로 두께 35 nm의 HfOx 막을 증착하였다. 최종적으로, solvent 및 불순물을 제거하기 위해 $180^{\circ}C$의 온도에서 10 분 동안 열처리를 진행하였으며, 상부 전극을 형성하기 위해 electron beam evaporation을 이용하여 Ti와 Al을 각각 50 nm, 100 nm의 두께로 증착하였다. ReRAM 동작에서 compliance current가 미치는 영향을 평가하기 위하여 compliance current를 10mA에서 1mA까지 변화시키면서 측정한 결과, $25^{\circ}C$에서는 compliance current의 크기와 상관없이 일정한 메모리 윈도우와 우수한 endurance 특성을 얻는 것을 확인하였다. 한편, $85^{\circ}C$의 고온에서 측정한 경우에는 1mA의 compliance current를 적용하였을 때, $25^{\circ}C$에서 측정된 메모리 윈도우 크기를 비슷하게 유지하면서 더 우수한 endurance 특성을 얻는 것을 확인하였다. 결과적으로, 용액공정 방법으로 제작된 ReRAM을 측정하는데 있어서 compliance current를 줄이면 보다 우수한 endurance 특성을 얻을 수 있으며, ReRAM 소자의 전력소비감소에 효과적이라고 기대된다.

• Applied Chemistry for Engineering
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• v.20 no.4
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• pp.407-410
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• 2009

18~19 wt% $KMnO_4$/$SiO_2-Al_2O_3$ with Si/Al = 1/5 and 1/10, and 20 wt% $KMnO_4$/$Al_2O_3$ were prepared by solvent evaporation method. Catalytic activity of ethylene abatement over those samples were evaluated and compared under the conditions of GHSV $1125h^{-1}$, ethylene gas (ethylene 0.2%, air 99.8%, relative humidity 50%) at 30, 40, 60 and $120^{\circ}C$ using a fixed-bed reactor. $KMnO_4$/$SiO_2-Al_2O_3$ was showed better performance than $KMnO_4$/$Al_2O_3$ by 170~210% at 30, $40^{\circ}C$, and by 60% at 60, $150^{\circ}C$, respectively.

• Journal of Life Science
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• v.24 no.2
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• pp.167-172
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• 2014

Optimal conditions for extraction of bakkenolide B from Petasites japonicus leaves were determined by using response surface methodology. A second-order Box-Behnken design representing three extraction temperatures (80, 100, $120^{\circ}C$), three extraction times (30, 45, 60 min), and three solvent pH's (5, 7, 9) was executed. The efficiency of the extraction conditions was defined using the ${\beta}$-hexosamidase assay by comparing both the bakkenolide B content and its anti-allergic activity expressed as extract inhibition on degranulation. The response surface plot described for the bakkenolide B content showed that the maximum content was predicted as 121.6 ${\mu}g/g$ with extraction conditions of $127.1^{\circ}C$, 46.6 min, and pH 7.7. Extraction temperature and time were important factors in determining bakkenolide B content. Using regression analysis, correlation between the inhibition effect of mast cell degranulation and bakkenolide B content was found to be low.

• Journal of Life Science
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• v.22 no.6
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• pp.807-814
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• 2012

Saururus chinensis has long been widely used in oriental folk medicines to treat diseases. In the current study, organic solvent fractions obtained from the main methanolic extract of S chinensis were evaluated for their antioxidative and related physiological activities. The antioxidant activity of the fractions was measured using DPPH free radical scavenging activity, increased in a dose-dependent manner, and the $ED_{50}$ of the ethyl acetate fractions exhibited a value of 12.84 ${\mu}g/ml$ higher than 27.22 ${\mu}g/ml$ compared to the BHT. Also, the cell viability of S. chinensis on $H_2O_2$-induced HDF cell death ($IC_{50}$) showed the highest cell viability of 89.39% in 50 ${\mu}g/ml$ of ethyl acetate fraction and 67.98% of visible cell survival rate in n-butanolic fraction. Meanwhile, all fractions of the S. chinensis extract led to a slight down regulation of the mRNA expression of fibulin-5, which is related to skin elasticity, and the ethyl acetate fraction having high antioxidant activity showed a markedly inhibitory effect on chick embryonic angiogenesis using the CAM assay. These results suggest that the ethyl acetate fraction of S. chinensis extract could be a good material in therapeutic application for antioxidant and related anti-angiogenesis activities.

• Journal of Life Science
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• v.28 no.6
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• pp.738-744
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• 2018

Sasa quelpaertensis Nakai is a native Korean plant that grows only on Mt. Halla of Jeju Island. Its leaf is used for a popular bamboo tea due to its various health-promoting properties, and it has been increasingly used as food and cosmetic ingredients. To utilize the S. quelpaertensis leaf efficiently, the preparation method for phytochemical-rich extract (PRE) using the leaf's residue was previously reported, which was produced after hot water extraction. This study was undertaken to evaluate the anti-oxidant and anti-inflammatory potential of PRE and its solvent fractions. The ethyl acetate fraction of PRE (EPRE) showed higher DPPH, ABTS, and superoxide radical scavenging activities, and it effectively inhibited intracellular reactive oxygen species (ROS) and nitric oxide (NO) production in lipopolysaccharides (LPS)-stimulated RAW 264.7 cells. EPRE also induced the expression of heme oxygenase-1 (HO-1) by increasing the level of nuclear factor E2-related factor 2 (Nrf2) in a nuclear fraction. The inhibiting effect of EPRE on LPS-induced NO production was partially reversed by the HO-1 inhibitor (zinc protoporphyrin, ZPP), suggesting that HO-1 is involved in suppressing NO production. Taken together, the results suggest that EPRE has potential as a promising anti- oxidant and anti-inflammatory agent.

• Korean Journal of Food Science and Technology
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• v.26 no.6
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• pp.690-695
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• 1994

The perilla seed and the germinated perilla seed $(25{\sim}28^{\circ}C$, $2{\sim}3\;days)$ were extracted by n-hexane, and from the extracted oil the antioxidative components were separated, and then the effect of the change in the contents of antioxidative components by germination on the oxidative stability of the perilla oil was studied. The perilla oils were solved acetone and methanol, and kept at $-60^{\circ}C$ overnight and separated into the frozen oil fraction and unfrozen solvent soluble fraction. By comparing the antioxidative stability of the frozen oil fraction the antioxidative components in the perilla oil were found to be methanol soluble. The methanol soluble fraction of perilla oil was applied to silica gel column chromatography and the separated fractions were compared in terms of antioxidative activity. The fraction of n-hexane : ethyl acetate (7 : 3, v/v) showing the highest antioxidative activity was further separated by TLC. The components included in the band $(R_f\;0.71)$ showing the highest antioxidative activity was separated by HPLC. Four peaks were observed on the HPLC chromatogram and the peak areas were changed by germination (perilla seed : peak 1; 46.5%, peak 2; 25.6%, peak 3; 22.6%, germinated perilla seed : peak 1; 43.8%, peak 2; 20.6%, peak 3; 29.8%). The comparative change in the contents of these components was considered to be one factor affecting the antioxidative stability of perilla oil by germination.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.9
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• pp.1268-1273
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• 2011

The present study was conducted to determine a feasible method of protein concentrate extraction from rice bran (RBPC) and its effect as a substitution for skim milk in early weaning pig diets. An investigation to extract protein concentrate from full fat rice bran was undertaken to determine the best ratio of water and rice bran, the amount of NaOH and a HCl solvent to use in a simple paddle-type mixer with modified spinning to produce RBPC. The results stated that the best ratio for water mixing in the RBPC extraction process was 1:5 with 20 g NaOH and 30 min in a paddle-type mixer at 300 rpm. A mix of 250 ml 0.2 N HCl was optimum for neutralization and protein precipitation. After the fluid was spun out with a washing machine, the sediment was left for 12-14 hours to complete the filtration. One kilogram of rice bran could produce an average of 324.5 gram RBPC and it contained 3.40% ash, 496.48 kcal of GE/100 gram, 1.94% crude fiber, 28.20% ether extract, 7.64% moisture and 16.66% crude protein, respectively. A total of 45 crossbred piglets, weaned at 3 weeks of age were allotted into control diet (A) and dietary treatments formulated with a four different rates of RBPC substitution for skim milk at a percentage of 25 (B), 50 (C), 77 (D) and 100 (E) respectively, in a randomized complete block (RCB) design. All piglets had free access to feed and water until 8 week of age when the experiment ended. Feed intake, average daily gain, growth rate and feed efficiency were not affected by dietary treatments. Blood test parameters after completion of the growth trial indicated normal health. Even though the mean of cell hemoglobin concentration was significantly different between treatments (p<0.05) it was still within the normal range. The cost difference for BW gain of 100% RBPC substituted for skim milk in the weaning diet was approximately 35% lower than that of the control and the relative cost of production was 96.67, 92.85, 70.75 and 64.48% lower for the replacement of 25, 50, 75 and 100% of skim milk respectively. These results implied that this technology is feasible for use by small scale farmers to improve their self-reliance.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.11
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• pp.1587-1594
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• 2010

This study was designed to investigate the effect of Artemisia capillaris extracts on the intestinal microflora. In agar diffusion method, the solvent fractions of Artemisia capillaris showed growth inhibition against the intestinal microflora. In particular, the chloroform fraction of Artemisia capillaris had strong antibacterial activity against Clostridium perfringens, Clostridium difficile, Eubacterium limosum, and Bacteroides fragilis, but did not show antibacterial activity against Bifidobacterium bifidum and Lactobacillus acidophilus. Most chloroform fraction of Artemisia capillaris inhibitory activities were not reduced by heat treatment or pH variation against C. perfringens, C. difficile, E. limosum, and B. fragilis. MICs of the chloroform fraction were 1.25 mg/mL against C. perfringens, E. limosum and B. fragilis and 2.5 mg/mL against C. difficile. MBCs of chloroform fraction were 5 mg/mL against C. perfringens, E. limosum and 2.5 mg/mL against C. difficile, B. fragilis. The ethyl acetate fraction of Artemisia capillaris showed $3.08{\pm}0.03$ mg/10 mg total polyphenol and $1.91{\pm}0.03$ mg/10 mg total flavonoid contents. In vivo tests were performed to investigate the influence of Artemisia capillaris extract on the intestinal microflora in rats. The results showed the possibilities of utilizing Artemisia capillaris extracts as a functional food component to control intestinal microflora.

• Applied Biological Chemistry
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• v.51 no.3
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• pp.212-218
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• 2008

This study was performed to determine the antimutagenic and anticancer effects of ethanol extract of buckwheat sprout using Ames test and SRB assay, respectively. An ethyl acetate fraction (200 ${\mu}/plate$) from the ethanol extract of buckwheat sprout showed inhibition rate of 80.6% against the mutagenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in Salmonella typhimurium TA100 strain. Also the ethyl acetate fraction (200 ${\mu}/plate$) showed higher antimutagenic activity than other fractions against the mutagenesis induced by 4-nitroquinoline-1-oxide (4NQO) in Salmonella typhimurium TA98 and TA100. In addition, the ethyl acetate fraction (200 ${\mu}/plate$) showed high antimutagenic effect of 80.9% and 85.9% against the mutation of TA98 and TA100 strains induced by 3-amino-1,4-dimethyl-5H-pyrido-(4,3-b)indol (Trp-P-1), respectively. The cytotoxic effects of each solvent fraction from the ethanol extract of buckwheat sprout against human cancer cell lines including lung carcinoma (A549), gastric carcinoma (AGS), breast adenocarcinoma (MCF-7), hepatocellular carcinoma (Hep3B), and colon adenocarcinoma (Colo 205) were investigated. The ethyl acetate fraction of buckwheat sprout ethanol extract at the concentration of 1.0 mg/ml showed strong cytotoxic activities of 70.3, 94.8, 79.6, 82.3, and 73.2% against A549, AGS, MCF-7, Hep3B and Colo 205 cancer cell lines, respectively.

• Journal of Applied Biological Chemistry
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• v.61 no.1
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• pp.47-50
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• 2018

Ricania shantungensis is a pest causiong problems in many crops. We tested the possibility of controling Ricania shantungensis using essential oil of Valeriana fauriei which were extracted by three different methods (steam distillation, solvent and supercritical extraction). Steam distillation were showed the most high mortality to adult ($1,040{\mu}L/mL$) and nymph ($2,370{\mu}L/mL$) of R. shantungensis. The yield of steam distillation extraction was 0.67%, which was lower than other methods. However, it is determined that steam extraction was showed higher efficiency by considering time and cost. The result of this study showed the possibility of control R. shantungensis by essential oil of V. fauriei.