• Applied Biological Chemistry
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• v.39 no.2
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• pp.159-164
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• 1996

Screening of anticoagulant activity was conducted for the hot water extracts of 73 kinds of medicinal herbs, 41 kinds of Korean edible plants, and 5 kinds of sea weeds using plasma recalcification test(Tr). In the first screening several extracts of the plants, Alisma calndiculatum, Corydalis ternata Panax notoginseng, Allium sativum, Ganderma luidum, Codium fragile, showed high activities. When the plants were reextracted with various solvent conditions, acidic water extracts of Codium fragile showed the highest activity in APTT. A crude polysaccharide fraction(CF-1) was prepared by methanol reflux, ethanol precipitation, dialysis and Iyophilization of the acid extracts. CF-1 comprised 80.8% total sugar consisting of arabinose, galactose and glucose as the main monomers, 8.7% protein, and 13.3% sulfate. The anticoagulant activity of CF-1 was not changed by pronase digestion, but decreased by periodate oxidation, and this indicated that the anticoagulant activity was attributed to the polysaccharide portion.

• Applied Chemistry for Engineering
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• v.17 no.3
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• pp.327-330
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• 2006

We investigated the usefulness of $NbO_{x}$ nanopillars as an etching mask of dry etching for the formation of Si nanodot arrays. The $NbO_{x}$ nanopillar arrays were prepared by the anodic aluminum oxidation process of Al and Nb thin films. The etch rate and etch profile of $NbO_{x}$ nanopillar arrays were examined by varying the experimental conditions such as the concentration of etch gas, coil rf power, and dc bias voltage in the reactive ion etch system using the inductively coupled plasma. As the concentration of $Cl_{2}$ gas increased, the etch rate of $NbO_{x}$nanopillars decreased. With increasing coil rf power and dc bias voltage, the etch rates were found to increase. The etch characteristics and etch mechanism of $NbO_{x}$ nanopillars were investigated by varying the etch time under the selected etch conditions.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.239-239
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• 2015

삼성, LG전자 등 다양한 사업부의 White Anodizing구현기술의 Need는 항상 존재하고 있으며, 특히 White와 Black Color의 콤비네이션으로 친환경 이미지 강조 및 핸드폰의 고급화에 필연적인 메탈화로 작년부터 White Anodizing의 수요요청이 쇄도하고 있다. 그러나 현행 공업용 Anodizing 기술(황산법)은 봉공처리 전 착색공정에서 Red, Blue, Black 등 염료분자와 달리 염료 분자가 비교적 큰 White 염료는 Anodizing으로 성장된 다공성피막 내부로 들어가지 못해 국내 Anodizing전문기업 뿐만아니라 일본 기업 및 연구소 등에서도 무수한 시도를 하고 있지만 현재까지는 완벽한 White Anodizing구현기술이 전무한 상태이다. 이에 당사는 알루미늄합금을 White의 안료나 염료가 아닌 알칼리전해액의 Pulse전류인가 PEO(Plasma electrolytic oxidation)처리 공정에 의거 White Anodizing기술을 개발하고자 하였다. 알칼리 전해질에 의한 Anodizing 처리기술로 White와 유사한 색상을 구현하고 있으나, 수요자가 요구하는 White Anodizing으로 제품을 양산하는데 어려움이 있어 기존 Anodizing 처리 대신 Pulse전류인가 PEO처리기술로 White Color를 구현하여 수요요청이 쇄도한 국내외 기업체에 공급하고자 한다. 본 기술은 알카리 전해액을 사용하므로 친환경적이며, 다공성 피막으로 인한 우수한 도장 밀착성, 실링처리에 의한 내식성 향상, PEO 피막의 우수한 경도 및 내마모성 등을 나타내며, 알루미늄뿐만 아니라 마그네슘합금, 티타늄 등에도 공히 적용이 가능하며, White Anodizing의 특화된 기술로 표면처리기술 우위 선점 및 원가절감 등이 가능하다. 당사는 알루미늄 아노다이징 전문 기업으로서 내식성 목적의 연질 아노다이징 처리 및 고내마모성을 목적으로 하는 자동차 부품 및 기계 부품용 경질 아노다이징 처리를 주로 수행하고 있다. 본 발표에서는 당사의 표면처리 기술 및 알루미늄의 아노다이징에 대한 소개를 하고자 한다.

• Fisheries and Aquatic Sciences
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• v.16 no.3
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• pp.149-158
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• 2013

We demonstrate enhanced growth, innate immunity and protection against hydrogen peroxide ($H_2O_2$)-induced protein oxidation and cellular DNA damage in olive flounder Paralichthys olivaceus fed a chitosan-coated moist pallet (MP) diet. A chitosan-based biopolymer coated MP as the experimental diet and a non-coated MP (control) was fed to olive flounder fish. Growth, including the average weight gain (g/fish), weight gain (%) and feed intake (g) of the fish group fed a chitosan-coated MP diet increased significantly. The survival rate was reported as 100% throughout the experimental period. Immunological parameters indicated higher mucus lysozyme activity and significantly higher fish skin mucus total protein content was observed in fish fed the chitosan-coated MP diet compared to the control. A blood plasma analysis revealed attenuation of cellular DNA and protein oxidative damage caused by $H_2O_2$-induced oxidative stress in the fish fed the chitosan-coated MP diet compared to the control group. Moreover, blood serum biochemical analysis revealed health-promoting effects, including significantly higher hemoglobin and total cholesterol levels in the fish fed the chitosan-coated MP diet compared to the control group. In conclusion, growth, innate immunity and protection against oxidative stresses were improved by feeding of the chitosan-coated MP diet to olive flounder reared in aquaculture.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3327-3332
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• 2010

We investigated the effects of newly synthesized 4-[(butylsulfinyl)methyl]-1,2-benzenediol (SMBD) on the prevention of atherosclerosis in hypercholesterolemic rabbits. SMBD exhibited stronger inhibition of $Cu^{2+}$-induced low-density lipoprotein oxidation than that of ascorbic acid or simvastatin. Three-month-old rabbits were fed an atherogenic diet containing 0.5% cholesterol and 10% coconut oil, while other two groups were given an atherogenic diet with intravenous injection of either simvastatin or SMBD (0.33 mg/kg/day) for 4 weeks. The concentrations of plasma cholesterol and thiobarbituric acid reactive substances were significantly decreased in SMBD groups, compared to the control group. Also, aortic lipid level in the SMBD group significantly lower than that in the control group. Furthermore, compared with the control group, the SMBD group significantly inhibited the increase of aortic intimal thickness by 36% via reducing of aortic reactive oxygen species and cyclooxygenase-2 protein levels. We conclude that raised antioxidant effect of SMBD results in significant prevention against hypercholesterolemia.

• Korean Journal of Materials Research
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• v.13 no.4
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• pp.233-238
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• 2003

Ferromagnetic tunnel junctions, Ta/Cu/Ta/NiFe/Cu/$Mn_{75}$ $Ir_{25}$ $Co_{70}$ $Fe_{30}$/Al-oxide, were fabricated by do magnetron sputtering and plasma oxidation process. The effect of annealing temperature on the local transport properties of the ferromagnetic tunnel junctions was studied using contact-mode Atomic Force Microscopy (AFM). The current images reflected the distribution of the barrier height determined by local I-V analysis. The contrast of the current image became more homogeneous and smooth after annealing at $280^{\circ}C$. And the average barrier height $\phi_{ave}$ increased and its standard deviation $\sigma_{\phi}$ X decreased. For the cases of the annealing temperature more than $300^{\circ}C$, the contrast of the current image became large again. And the average barrier height $\phi_{ave}$ decreased and its standard deviation $\sigma_{\phi}$ increased. Also, the current histogram had a long tail in the high current region and became asymmetric. This result means the generation of the leakage current that is resulted from the local generation of a low barrier height region. In order to obtain the high tunnel magnetoresistance(TMR) ratio, the increase of the average barrier height and the decrease of the barrier height fluctuation must be strictly controlled.led.

• Journal of the Korean institute of surface engineering
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• v.48 no.6
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• pp.260-268
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• 2015

The thermal barrier coating (TBC) for inner wall of liquid-fuel rocket combustor consists of NiCrAlY as bonding layer and $ZrO_2$ as a top layer. In most case, the plasma spray coating is used for TBC process and this process has inherent possibility of cracking due to large difference in thermal expansion coefficients among bonding layer, top layer and metal substrate. In this paper, we suggest crack-free TBC process by using a precise electrodeposition technique. Electrodeposited Ni-P/Cr double layer has similar thermal expansion coefficient to the Cu alloy substrate resulting in superior thermal barrier performance and high temperature oxidation resistance. We studied the effects of phosphorous concentrations (2.12 wt%, 6.97 wt%, and 10.53 wt%) on the annealing behavior ($750^{\circ}C$) of Ni-P samples and Cr double layered electrodeposits. Annealing temperature was simulated by combustion test condition. Also, we conducted SEM/EDS and XRD analysis for Ni-P/Cr samples. The results showed that the band layers between Ni-P and Cr are Ni and Cr, and has no formed with heat treatment. These band layers were solid solution of Cr and Ni which is formed by interdiffusion of both alloy elements. In addition, the P was not found in it. The thickness of band layer was increased with increasing annealing time. We expected that the band layer can improve the adhesion between Cr and Ni-P.

• Particle and aerosol research
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• v.15 no.1
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• pp.1-13
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• 2019

Current desulfurization and denitrification technologies have reached a considerable level in terms of reduction efficiency. However, when compared with the simultaneous reduction technology, the individual reduction technologies have issues such as economic disadvantages due to the difficulty to scale-up apparatus, secondary pollution from wastewater/waste during the treatment process, requirement of large facilities for post-treatment, and increased installation costs. Therefore, it is necessary to enable practical application of simultaneous SOx and NOx treatment technologies to remove two or more contaminants in one process. The present study analyzes a technology capable of maintaining simultaneous treatment of SOx and NOx even at low temperatures due to the electrochemically generated strong oxidation of the wet-pulse complex system. This system also reduces unreacted residual gas and secondary products through the wet scrubbing process. It addresses common problems of the existing fuel gas treatment methods such as SDR, SCR, and activated carbon adsorption (i.e., low treatment efficiency, expensive maintenance cost, large installation area, and energy loss). Experiments were performed with varying variables such as pulse voltage, reaction temperature, chemicals and additives ratios, liquid/gas ratio, structure of the aeration cleaning nozzle, and gas inlet concentration. The performance of individual and complex processes using the wet-pulse discharge reaction were analyzed and compared.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.5
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• pp.125-131
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• 2018

Some propellants in a liquid rocket engine are burned in the pre-burner of a staged combustion cycle engine, resulting hot gas drives the turbine. The burned gas passing through the turbine is supplied to the combustor at high temperature and pressure. The form of the gas can be fuel rich or oxidizer rich dependent upon the mixture ratio or the engine scheme. When the cycle works at oxidizer-rich condition, the metal pipes composing the engine can be ignited or even exploded by an impact of very a small particle. In this study, we developed the powder combination and processes for an anti-oxidation coating through the analysis of various coating materials.

• Journal of the Korean institute of surface engineering
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• v.55 no.1
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• pp.24-31
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• 2022

This study investigated the effect of pre-treatment on the PEO film formation of AZ91 Mg alloy. The pre-treatment was conducted for 10 min at room temperature in 0.5 M oxalic acid (C₂H₂O₄) solution containing various ammonium fluoride (NH₄F) concentrations. The pre-treated AZ91 Mg specimens were anodized at 100 mA/cm² of 300 Hz AC for 2 min in 0.1 M NaOH + 0.4 M Na₂SiO₃ solution. When AZ91 Mg alloy was pretreated in 0.5 M oxalic acid with NH₄F concentration less than 0.3 M, continuous dissolution of the AZ91 Mg alloy occurred together with the formation of black smuts and arc initiation time for PEO film formation was very late. It was noticed that corrosion rate of the AZ91 Mg alloy became faster if small amount of NH₄F concentration, 0.1 M, is added. The fast corrosion is attributable to fast formation of porous fluoride together with porous oxides in the reaction products. On the other hand, when AZ91 Mg alloy was pretreated in 0.5 M oxalic acid with sufficient NH₄F more than 0.3 M, a thin and dense protective film was formed on the AZ91 Mg alloy surface which resulted in faster initiation of arcs and formation of PEO film.