• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.51-59
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• 2005

수소 분리막의 적용 분야는 석탄가스, 천연가스, 메탄가스 혼합기체이며, 고온/고압 및 수소농도가 낮은 혼합기체에서 고순도의 수소를 제조하는 곳이다. 특히 치밀질 세라믹 멤브레인은 고온에서 가스화한 석탄가스나 차세대의 쓰레기 처리 기술인 가스화 용융처리에서 생긴 고온가스로부터 고순도의 수소를 분리할 수 있다. 분리한 수소는 고온을 유지하기 때문에 연료전지 발전에 최적이다. 종래의 연료전지는 발전을 위해서 수소의 가열이 필요했으나 이것이 불필요하게 되어 발전 전체의 효율이 향상된다. 석유화학 산업에서 발생하는 혼합기체에서 수소를 분리하여 사용하고 남은 기체는 연료로 재사용할 수 있다. 분리막의 재질로는 고분자계가 개발되고 있으며 고분자 지지체에 백금이나 로듐과 같은 촉매를 코팅하는 방법이다. 이는 기공의 제어가 용이하고 대량생산이 가능한 장점이 있지만 고온에서 사용이 불가능하고 입자상 물질에 의해 분리막의 손상이 문제가 되고 있다. 이에 비해 치밀질 세라믹 멤브레인은 세라믹의 특성에 의해 고온 및 고압에서도 적용이 가능하며, 실온이나 저압의 조건에서도 적용이 가능한 특징을 가진다. $900^{\circ}C$의 고온에서 적용시 세라믹 멤브레인에는 특성열화가 없어 수명이 긴 장점을 가지게 된다. 수소가 포함되어 있는 기체에서 수소 만을 분리하는 방법은 흡착이나 분리막을 이용하는 방법이 일반적이며 흡착에 의한 방법은 일부 실용화가 진행되고 있다. 고효율의 수소를 분리하는 방법으로 분리막을 이용하는 방법이 있다. 현재 치밀질 수소 분리막의 연구는 외국(미국, 일본 등)에서도 초기 연구 단계이다. 국내에서도 이런 연구가 선행되어 외국과의 기술 격차를 줄이고 에너지 자원에 대한 확보가 필요하기 때문에 이 연구가 수행되었다. 치밀질 멤브레인의 소재로는 proton 및 전자전도가 가능한 소재로서 Ba-Ce-Y계를 기본조성으로 하여 내구성과 전기전도도를 향상시키기 위해 Ca, La, In, Yb를 치환하였다. 제조한 재료의 물리화학적 특성을 평가하였고, 수소여과 장치를 이용하여 여과 효율을 평가하였다.

• Polymer(Korea)
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• v.30 no.5
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• pp.402-406
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• 2006

New antibacterial Polyurethane foams for car seat with Urushiol extracted from a natural lacquer were prepared. Influences of antibacterial agent's concentration on the reactivity with isocyanate and the mechanical properties of foams were investigated. It was observed that the urethane formation reaction was delayed a little when the amount of Urushiol was increased. However, the foams made using Urushiol showed similar property to the neat polyurethane foam. In terms of antibacterial property, the foams prepared with Urushiol showed better performance than the neat polyurethane foam.

• Applied Biological Chemistry
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• v.38 no.5
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• pp.447-451
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• 1995

Chitosan, a deacetylated polymer of chitin, was applied and characterized as an adsorbent for a dye Toluidine Blue O. The adsorption of Toluidine Blue O by chitosan was affected by the particle sire and mass of chitosan, initial dye concentration, reaction time, and solution pH. More dye was adsorbed the smaller the chitosan particles. When initial ratio of dye to chitosan was over 1 : 500, the adsorption of dye was rapidly declined. Adsorption rate of dye to chitosan showed 2 phases, rapidly occurred one at the beginning within 3 min and thereafter very slowly occurred one. The amount of dye adsorbed was increased with increase in pH.

• Polymer(Korea)
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• v.37 no.5
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• pp.613-617
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• 2013

The effects of nano size kenaf cellulose fiber on mechanical property of polypropylene (PP) composite were investigated. The addition of nano-kenaf in place of natural kenaf showed higher tensile strength, flexural strength, impact strength, and heat deflection temperature compared to the natural kenaf filled PP composite, while it shows lower melt flow index, elongation%, and flexural modulus. These seemed to be due to the increased surface area of nano-kenaf fiber contacting PP matrix and reduced impurities such as volatile extractives on the fiber surface.

• Polymer(Korea)
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• v.24 no.3
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• pp.431-436
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• 2000

To improve the thermal and mechanical properties of homo poly(L-lactic acid), DL-mandelic acid, one of the natural $\alpha$-hydroxy acid with aromatic ring as the side-chain residue was used as the comonomer. Copolymers with different contents of mandelic acid were prepared and characterized. The resulting copolymers were mostly amorphous. As the amount of mandelic acid in the monomer feed increased, the molecular weight of the resulting polymers tended to decrease linearly. T$_{g}$ and T$_{d}$ of the copolymer, however, were found to shift toward higher temperature, suggesting the improved thermal stability by increasing content of mandelic acid moiety. Tensile measurements of cast films showed somewhat improved values in the copolymers with mandelic acid content of 5 and 10 wt%.%.%.

• Korean Journal of Materials Research
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• v.32 no.12
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• pp.533-537
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• 2022

Flexible zinc-air batteries have many merits, including low cost, high safety, environmentally friendliness applicability, etc. One of the key factors to improve the performance of flexible zinc-air batteries is to use a gel electrolyte. In this study, gel electrolytes were synthesized from potato, sweet potato, and corn starch. In a comparison of each starch, the corn starch-based gel electrolyte showed the highest discharge capacity of 12.41 mAh/cm² in 20 mA and 6.47 mAh/cm² in 30 mA. It also delivered a higher specific discharge capacity of 7.06 mAh/cm² than the other materials after 100° bending. In addition, the electrochemical impedance spectroscopy (EIS) was analyzed to calculate the ionic conductivity. The potato, sweet potato, and corn starch-based gel electrolytes showed electrolyte resistances (Re) of 0.306, 0.298, and 0.207 Ω, respectively. In addition, the corn starch-based gel electrolyte delivered the highest ionic conductivity of 0.121 S cm^-1 among the other gel electrolytes. Thus, the corn starch-based gel electrolyte was verified to improve the performance of flexible zinc-air batteries.

• Journal of the Korean Applied Science and Technology
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• v.34 no.2
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• pp.357-366
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• 2017

Natural pigments are materials that express color and have been used in foods, cosmetics, medicine and so on. Since natural pigments are extracted from animals and plants, they are not uniform in size. Red pigments in particular are more lipophilic than other color pigments and tend to aggregate easily in aqueous solutions which make it difficult to reproduce the specific color due to size change. Found to be an allergen and the growing aversion for it to be used in foods, cochineal pigment, an animal pigment used for red pigments is being used less. In this study, red vegetable pigment lycopene extract and gardenia yellow was made uniform in size by ball-milling, then asymmetrical flow-field flow fractionation (AsFlFFF) and dynamic light scattering (DLS) were used to measure the size, and a color meter was used to confirm the color. Experimental results showed that the pigment particles were large in size and size distribution was wide before milling, but the size of the particles decreased and size distribution narrowed after milling. Color meter measurements showed that as the milling time increased, the size of the pigment particles decreased and the brightness, redness, and yellowness increased indicating a bright red color.

• Journal of Life Science
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• v.24 no.5
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• pp.498-504
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• 2014

Mammalian hyaluronidases (HAase, EC 3.2.1.35) are a family of enzymes that hydrolyse N-acetyl-D-glucosamine (1-4) glycosidic bonds in hyaluronic acid, which is found in skin, cartilage, and the vitreous body. Although HAase is generally present in an inactive form within subcellular lysosomes, it is released in an active form in some types of inflammation and tissue injuries, thereby contributing to the inflammatory response. The HAase inhibitory activity of 500 methanolic extracts of 500 species from medicinal plants was screened using a Morgan microplate assay. The viscosity of the hyaluronic acid was measured with an Ubbelohde viscometer. Three MeOH extracts inhibited more than 50% of HAase activity at a concentration of 2 mg/ml. HAase inhibitory rates (%) of three species of medicinal plant extracts, Styrax japonica, Deutzia coreana, and Osmanthus insularis were 57.28%, 53.50%, and 53.19%, respectively. The rate of HAase inhibition of the extracts was dose dependent. In the HAase inhibitory assay using the Ubbelohde viscometer, the results were in good agreement with the results from the Morgan assay. The results suggest that HAase inhibitory compounds extracted from the stem of S. japonica, D. coreana, and O. insularis might be multifunctional and prevent the degradation of hyaluronic acid and the induction of allergic reactions and inflammation.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.32 no.3 s.58
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• pp.149-152
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• 2006

Natural safflower oleosomes are small ($1{\sim}3{\mu}m$) spherical shaped "reservoir", inside which the seed stores triglycerides for use as a future energy source. The surface of the oleosome is covered with a high molecular weight ($20{\sim}24$ KDa) oleosin protein which has been demonstrated to have emulsification properties. Traditionally, oleosomes from oil bearing seeds such as safflower were simply crushed to liberate the oil within. Our patented DermaSphere technology allows for the isolation of oleosomes in the intact state. Once isolated, these materials can be used in skin care formulations to deliver the emolliency, occlusivity, and anti-oxidant effects typically associated with safflower oil. However, because of the presence of the emulsifying oleosin protein covering the spherical oil body, oleosomes have self-emulsification property as well as can emulsify other oil phase in typical oil-in-water (O/W) emulsion. The oleosomes can literally serve as the entire non-active portion of the oil phase of a typical skin care product. Most importantly, natural oleosomes can be loaded with other oil-soluble active materials and can therefore be used as delivery systems for improved cosmetic efficacies. Oleosomes can be loaded with various actives, such as fragrances, vitamins, inset repellents, and UV chromophores. The loaded oleosomes can be utilized to either protect the active ingredients within the formulation itself or to allow for control release of those actives over time.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.6
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• pp.686-692
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• 1992

The present study was carried out to examine the antioxidative actions between the products of amino-carbonyl reaction and commercial antioxidants, and investigate their synergistic effects. Nondialyzable melanoidins exhibited more significantly in the antioxidative action than unfractionated meanoidins did. Also, in the case of unfractionated melanoidins, both glycine and histidine were more effective than aspartic acid for the antioxidative action. There was no significant difference among amino acids in the action of nondialyzable melanoidins. The unfractionated melanoidin was not as good as antioxidative action of the synthetic antioxidants, butylated hydroxytoluene, tert-butyl hydroquinone and ascorbic acid ; however, the one was superior to that of natural antioxidants, ${\alpha}$-tocopherol and lecithin. Otherwise, the action of nondialyzable melanoidin was similar to that of synthetic antioxidant. The synergistic effects were increased in using melanoidin with ${\alpha}$-tocopherol and lecithin except for the systems of fructose-aspartic acid and fructose-glycine in unfractionated melanoidins.