• 한국자기학회지
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• 제4권4호
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• pp.326-334
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• 1994

친수성-고점도 자성유체를 Nd-영구자석과 병용하여 기름밀봉 장치로의 개발을 목표로 실험 검토하였다. etylene glycol 액상중에 $Fe_{3}O_{4}$를 분산시킨 자성유체는 매질의 비등점이 다른 액상보다 높고 점성이 높아서 기름밀봉 성능을 향상시킬 수 있을 뿐만 아니라 본 장치의 부품중 대부분 을 이루고 있는 철강재를 부식시키지 않았다. 본 자성유체중 $Fe_{3}O_{4}$ 농도가 증가할수록 점도 와 자성율이 증가하여 기름밀봉 성능을 향상시킬 수 있었다. 본 장치는 대기압하에서 기름밀봉 성능이 매우 우수하였다.

• 한국축산식품학회지
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• 제34권3호
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• pp.287-296
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• 2014

The physicochemical and functional traits for loin muscles of Hanwoo steers were compared by quality grade (QG). A total of 500 Hanwoo steers were slaughtered, their carcasses were categorized into four groups (QG 1++, 1+, 1, and 2), and the longissimus dorsi muscles were analyzed. QG 1++ group had the highest fat and lowest moisture content (p<0.05). QG 1++ showed higher $L^*$ and $b^*$ color values, higher cooking loss, and lower shear force values, compared with the other groups (p<0.05). The flavor, tenderness, juiciness, and preference scores by sensory evaluation were highly ranked for premium QG groups (1++ and 1+). Regarding the micro compounds, QG 1 and QG 2 had greater amounts of inosine monophosphate, and QG 2 had greater amounts of anserine, carnosine, and creatine, than QG 1++ (p<0.05). QG 1++ and 1+ had higher percentages of oleic acid (C18:1) than QG 2 (p<0.05). Within premium QG 1++ and 1+, the results of the nucleotides, free amino acids, dipeptides, and fatty acids did not show any distinctive differences. Hanwoo beef as determined by the current grading system was not significantly different in terms of functional components; the only significant difference was in intramuscular fat content.

• Journal of Ginseng Research
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• 제19권3호
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• pp.212-218
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• 1995

A human hepatoma cell line, hep G2, was used to investigate the mechanism of serum cholesterol reduction by ginseng total saponin, ginsenoside-$Rb_1$, - $Rb_2$, and non-saponin fraction (ether extraction). Hep G2 cells were incubated in 10 $\mu\textrm{g}$/ml of cholesterol containing serum free-RPMl1640 medium with various concentration of ginseng components. The amounts of cholesterol in Hep G2 cells were decreased to maximum 51% in total saponin or two ginsenoside-treated groups while there was 137% increase in cholesterol level of control group as compared with that of normal group. Nonsaponin groups did not show the same effect. In order to elucidate the observed changes in the amount of cholesterol, the activity of amyl CoA : cholesterol acyltransferase (ACAT) in groups showing remarkable reduction in cholesterol amount, i.e., total saponin 10-6%, ginsenoside-$Rb_1$ $10^{-4}$%, ginsenoside-$Rb_2$, $10^{-4}$%, and non-saponin fraction $10^{-4}$%, was assayed using [1-$^{-14}C$%]oleic acid as enzyme substrate. The activity of ACAT was increased in all groups tested as compared with that of control group except for non-saponin group cultured in water soluble cholesterol containing medium. The serum cholesterol lowering effects of ginseng components can partially be attributed to the increased hepatocellular ACAT activity.

• 한국자기학회지
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• 제9권2호
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• pp.121-126
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• 1999

친수성 철계 자성유체의 제조와 이 자성유체를 Nd-영구자석과 병용하여 기름 밀봉 장치의 개발을 목적으로 실험검토한 결과 다음과 같은 결론을 얻었다. 1)평균 입경 100$\AA$, 자화값 125.5emu/g, 대기중 15$0^{\circ}C$까지 산화 변질성이 없는 실리카 피착 철 초미립자의 표면에 오레인산 이온, D.B.S. 이온 및 T.M.A. 이온을 흡착한 후 ethylene glycol 용액중에 분산시켜 친수성 철 분말 자성유체를 제조할 수 있었다. 2)이상의 친수성 철 분말 자성유체[70%(g/ )Fe]를 영구자석(3200 Gauss)과 병용하여 기름 밀봉 장치에 응용한 결과 영구자석의 설치 개수를 영구자석 6단 그리고 구동축과 밀봉 장치 사이 간격 0.2mm의 조건에서 압력 7400g/$\textrm{cm}^2$까지 견딜 수 있는 우수한 내압 특성을 얻었다.

• 한국토양비료학회지
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• 제44권4호
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• pp.597-599
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• 2011

This study was conducted to find out the optimum nitrogen application rate for the stable production of rape in the newly reclaimed land located at Gangwhal region of Saemangum reclaimed land in which the soil is sandy loam (Munpo series). There were five treatments of nitrogen fertilization from zero to 60% increment based on the standard fertilization of $150kg\;ha^{-1}$. The growth of rape (Sunmang) was not affected by salt content while soil salinity was increased at blossoming season of rape. Compared to yield of standard fertilization the yield and the content of oleic acid of rape were increased by 4~26% with the increasing additional nitrogen fertilizer. The results obtained from the growth and yield of rape in this study indicated that it was possible to cultivate rape in a newly reclaimed land if soil salinity was kept below $3dS\;m^{-1}$.

• 한국재료학회지
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• 제22권7호
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• pp.362-367
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• 2012

Magnetite nanoparticles(NPs) have been the subject of much interest by researchers owing to their potential use as magnetic carriers in drug targeting and as a tumor treatment in cases of hyperthermia. However, magnetite nanoparticles with 10 nm in diameter easily aggregate and thus create large secondary particles. To disperse magnetite nanoparticles, this study proposes the infiltration of magnetite nanoparticles into hybrid silica aerogels. The feasible dispersion of magnetite is necessary to target tumor cells and to treat hyperthermia. Magnetite NPs have been synthesized by coprecipitation, hydrothermal and thermal decomposition methods. In particular, monodisperse magnetite NPs are known to be produced by the thermal decomposition of iron oleate. In this study, we thermally decomposed iron acetylacetonate in the presence of oleic acid, oleylamine and 1,2 hexadecanediol. We also attempted to disperse magnetite NPs within a mesoporous aerogels. Methyltriethoxysilicate(MTEOS)-based hybrid silica aerogels were synthesized by a supercritical drying method. To incorporate the magnetite nanoparticles into the hybrid aerogels, we devised two methods: adding the synthesized aerogel into a magnetite precursor solution followed by nucleation and crystal growth within the pores of the aerogels, and the infiltration of magnetite nanoparticles synthesized beforehand into aerogel matrices by immersing the aerogels in a magnetite nanoparticle colloid solution. An analysis using a vibrating sample magnetometer showed that approximately 20% of the magnetite nanoparticles were well dispersed in the aerogels. The composite samples showed that heating under an inductive magnetic field to a temperature of $45^{\circ}C$ is possible.

• 한국미생물·생명공학회지
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• 제47권1호
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• pp.87-95
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• 2019

Esterase produced by Acinetobacter sp. B1 (strain B1) was optimized by means of one-variable-at-a-time and response surface methodologies. Results of the one-variable-at-a-time experiment showed that Tween 80 significantly increased esterase production of strain B1. The addition of Tween 80 to the culture medium increased the biomass and esterase activity of strain B1, stimulated content of total extracellular protein, and enhanced the oleic acid (C18:1) composition in the cell membrane of strain B1. The influence of eight culture variables on esterase production was evaluated by Plackett-Burman design. Results showed that Tween 80, pH, and $K_2HPO_4$ significantly affected the esterase production of strain B1. Tween 80, pH, and $K_2HPO_4$ were further optimized by central composite design. Under the optimized conditions (w/v, soluble starch 2.5%, tryptone 1.5%, Tween 80 0.8%, $K_2HPO_4$ 0.5%, NaCl 0.5%, pH 8.0, inoculum size 1%, and inoculum age 24 h), the maximum esterase activity of strain B1 was 152.13 U/ml, which was 10-fold higher than that of non-optimization after 36 h cultivation.

• 한국재료학회지
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• 제31권1호
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• pp.8-15
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• 2021

Transparent, photocatalytic, and self-cleaning TiO2 thin film is developed by TiO2 sol-gel coating on glass and polycarbonate (PC) substrates. Acetyl acetone (AcAc) suppresses the precipitation of TiO2 by forming a yellowish (complex) transparent sol-gel. XPS analysis confirms the presence of Ti2p and O1s in the thin films on glass and PC substrates. The TiO2-sol is prepared by stabilizing titanium (IV) isopropoxide (TTIP) with diethylamine and methyl alcohol. The addition of AcAcsilane coupling solution to the TiO2-sol instantaneously turns to yellowish color owing to the complexing of titanium with AcAc. The AcAc solution substantially improves the photocatalytic property of the TiO2 coating layer in MB solutions. The coated TiO2 film exhibits super hydrophilicity without and with light irradiation. The TiO2 thin film stabilized by adding 8.7 wt% AcAc shows the highest photo-degradation for methylene blue (MB) solution under UV light irradiation. Also, the optimum photocatalytic activity is obtained for the 8.7 wt% AcAc-stabilized TiO2 coating layer calcined at 450 ℃. The thin-films on glass exhibit fast self-cleaning from oleic acid contamination within 45 min of UV-light irradiation. The appropriate curing time at 140 ℃ improves the anti-fogging and thermal stability of the TiO2 film coated on PC substrate. The watermark-free PC substrate is particularly beneficial to combat fogging problems of transparent substrates.

• 한국미생물·생명공학회지
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• 제48권4호
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• pp.491-505
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• 2020

A newly isolated strain, Proteus vulgaris OR34, from olive mill waste was found to secrete an alkaline extracellular lipase at 11 U·ml-1 when cultivated on an optimized liquid medium. This lipase was purified 94.64-fold with a total yield of 9.11% and its maximal specific activity was shown to be 3232.58 and 1777.92 U·mg-1 when evaluated using the pH-stat technique at 55℃ and pH 9 and Tributyrin TC4 or olive oil as the substrate. The molecular mass of the pure OR34 lipase was estimated to be around 31 kDa, as revealed by SDS-PAGE and its substrate specificity was investigated using a variety of triglycerides. This assay revealed that OR34 lipase preferred short and medium chain fatty acids. In addition, this lipase was stable in the presence of high concentrations of bile salt (NaDC) and calcium ions appear not to be necessary for its activity. This lipase was inhibited by THL (Orlistat) which confirmed its identity as a serine enzyme. In addition, the immobilization of OR34 lipase by adsorption onto calcium carbonate increased its stability at higher temperatures and within a larger pH range. The immobilized lipase exhibited a high tolerance to organic solvents and retained 60% of its activity after 10 months of storage at 4℃. Finally, the OR34 lipase was applied in biodiesel synthesis via oleic acid mediated esterification of methanol when using hexane as solvent. The best conversion yield (67%) was obtained at 12 h and 40℃ using the immobilized enzyme and this enzyme could be reused for six cycles with the same efficiency.

• 공업화학
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• 제33권6호
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• pp.606-612
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• 2022

수용액에서 수용성 염료를 소수성 염료로 전환시킨 후 마이크로 버블을 이용한 침전 및 부상응집에 의한 염료를 제거하는 연구를 수행하였다. 양이온성 염료에 음이온 collector를 반응시키며, 또한 음이온성 염료에 양이온 collector를 첨가하여 소수성으로 변환시켰다. 소수성으로 전환된 염료 용액을 회분식 반응기에 저장하여 마이크로 버블을 분사시켜 색을 제거하였다. 염료 용액을 제조하기 위해 Basic Yellow 1 및 Direct Orange 10을 사용하였으며, sodium dodecyl sulfate, oleic acid sodium salt 및 amine류와 같은 음이온 및 양이온 collector를 사용하면 색 제거에 효과적이었으며, 모든 색은 8분 이내에 제거되었다. 색 제거는 collector의 첨가량과 수용액 pH의 영향을 받으며, 염료농도에 비해 극히 소량의 계면활성제를 첨가하였을 경우에는 pH에 의존하였으나, 염료농도와 비슷한 collector 양을 첨가하였을 경우에는 pH에 의존하지 않았음을 알 수 있었다. 그 이유는 collector와 염료가 1:1M로 반응하여 소수성이 완전히 부여되어야 제거됨을 알 수 있었다.