• Elastomers and Composites
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• v.3 no.1
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• pp.62-74
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• 1968

천연(天然)고무 및 합성(合成) 고(高) cis 1 : 4 polyisoprene, 대표적(代表的)으로 'Natsyn 400'의 가공(加工), 배합(配合) 또는 가황체(加黃體)의 성질(性質)들의 차이점(差異點)들에 대(對)하여 설명(說明)하였다. 합성중합체(合成重合體)는 미리 소연(素鍊)함이 없이 충전제(充塡劑)를 첨가(添加)함으로서 가공(加工)이 용역(容易)하였으며 CV형(形) 천연(天然)고무에 있어서도 이점(利點)이 나타났다. 천연(天然)고무 배합물(配合物)은 점착성(粘着性)이 좋으며, 특(特)히 미가황물(未加黃物)의 강도(强度)가 현저(顯著)하게 우수(優秀)하다. 가황과정(加黃過程) 및 몇몇가황체(加黃體)의 성질(性質)에 있어서의 차이(差異)는 비(非)고무질(質)을 함유(含有)하지 않는 Natsyn으로 나타난다. 기타(其他)의 가황체성질(加黃體性質)의 차이(差異)는 천연(天然)고무에 있어서 그 가황체(加黃體)가 인장시(引張時)에 결정(結晶)하는 경향(傾向)을 크게 나타내고 있고 특(特)히 고온(高溫)에서 이들 차이(差異)가 현저(顯著)하다.

• Korean Journal of Food Science and Technology
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• v.29 no.5
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• pp.860-868
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• 1997

The effects of oil unsaponifiables (8 species) and methanolic plant extracts (53 species) on the thermal oxidation of oils during 14 or 16 hour heating at $180^{\circ}C$ were studied by analyzing the fatty acid composition of soybean oil or cottonseed oil. All the unsaponifiables tested did not show any antioxidative activities on the thermal oxidation of soybean oil. However, among the 53 species of methanolic plant extracts, some species (Rheum undulatum L., Chelidonium majus L. var. asiaticum and Eugennia caryopyllata T.) showed very strong antioxidative activities on the thermal oxidation of cottonseed oil. The antioxidative activities of methanolic extracts of these 3 species on thermal oxidation of cottonseed oil during an extended heating period were also studied by heating cottonseed oils for 7 hours a day for 8 days at $180^{\circ}C$. The methanolic extracts of Chelidonium majus L. v. asiaticum and Eugennia caryopyllata T. greatly reduced both polymer formation and linoleic acid decomposition after the 8 day heating at $180^{\circ}C$. However, the methanolic extracts of Rheum undulatum L. was effective for the reduction of polymer formation, but not for the reduction of linoleic acid decomposition.

• Polymer(Korea)
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• v.34 no.1
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• pp.38-44
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• 2010

Core-shell particles of inorganic/organic pair were synthesized from $CaCO_3$ absorbed sodium dodecyl benzene sulfonate(SDBS) surfactant. Shell components were synthesized by sequential emulsion polymerization. Various monomers were used as shell components such as methyl methacrylate(MMA), ethyl acrylate(EA), butyl acrylate(BA), and styrene(St). Ammonium persulfate(APS) was used as an initiator and 2-ethylhexyl acylate(2-EHA) was used as a functional monomer, In the $CaCO_3$/organic core-shell particle polymerization, $CaCO_3$ absorbed surfactant SDBS of 0.5 wt% was prepared first and then core $CaCO_3$ was encapsulated by emulsion polymerization. 0.1 wt% of APS was added sequentially to minimize the formation of new monomer particle during shell polymerization. The structure of inorganic/organic core-shell particles were characterized by measuring the decomposition degree of $CaCO_3$ using HCl solution, thermogravimetric analyzer, scanning electron microscope, and transmission electron microscope.

• Composites Research
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• v.27 no.6
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• pp.242-247
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• 2014

The fabrication of flexible electrodes coated on the surface of a dielectric elastomer film, which is a type of electroactive polymer (EAP), was carried out. Controlled amounts of Xylitol powder were added (10, 30, 50 and 70 wt%) to the commercial conductive polymer (PEDOT:PSS) to enhance resilience of the electrode. To check resilience of the fabricated composite electrodes, tensile tests were carried out using silicone films coated with the polymer electrodes. From the test results, it was found that 70 wt% Xylitol containing conductive polymer had excellent elongation and high failure strains. Furthermore, surface of the silicone film was uniformly polished with various abrading papers to enhance the wettability of the conductive polymers on the surface of the silicone film. It was found that the silicone film polished with #120 abrading paper had the best wettability and guaranteed excellent bonding behavior.

• Applied Chemistry for Engineering
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• v.3 no.3
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• pp.499-506
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• 1992

Copolymer of Styrene and GMA(glycidyl methachylate), having reactive ratios of $r_1=0.53$, $r_2=0.44$, was synthesized in dioxane using AIBN as free radical initiator. Followed by the reaction of ethylene diamine with copolymer PGS, amine groups were introduced to the PGS(NPGS). The composition of copolymer was determined by elemental analyzer. Poly(glycidyl methacrylate) (PGMA) was obtained in benzene using AIBN as free radical initiator. The NPGS-PGMA blend of 50/50 composition was prepared by mixing these polymers in THF at $65^{\circ}C$. Glass transition temperature (Tg) of NPGS-PGMA blend was measured by DSC. The blend showed a single Tg. Accordingly, it was clear that the NPGS was compatible with PGMA. An intermolecular reaction between amine groups of NPGS and epoxy groups of PGMA imparts compatibility in the NPGS-PGMA blend. When the NPGS-PGMA blend was added to the incompatible PS-PGMA blend, PS-PGMA blend showed Tg change. Scanning Electron Micrograph(SEM) showed a fine morphology in this blend. Consequently, it was apparent that the NPGS-PGMA blend acted as a compatibilizer for the PS-PGMA blend.

• Applied Chemistry for Engineering
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• v.7 no.1
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• pp.75-82
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• 1996

Acrylic acid was graft-copolymerized on polyethylene film in the presence of additives such as acid and $FeSO_4(NH_4)_2SO_4{\cdot}6H_2O$ using peroxide grafting technique by ${\gamma}$-ray and electron beam, and the effect of $FeSO_4(NH_4)_2SO_4{\cdot}6H_2O$ and acid on the grafting yield was evaluated. The grafting mechanism and the physical property of grafted films were also examined. The results showed that the inclusion of $FeSO_4(NH_4)_2SO_4{\cdot}6H_2O$ in acidified acrylic acid grafting solution was extremely beneficial and led to a most unusual enhancement effect in the radiation grafting. In the other hand, inclusion of mineral acid in the grafting solution in the absence of $FeSO_4(NH_4)_2SO_4{\cdot}6H_2O$ could not lead to he suitable grafting reaction by the severe homopolymerization of acrylic acid. The addition of $H_2SO_4$, and HCl led to much higher grafting yield than $HNO_3$and $CH_3COOH$. It was shown that grafting yield of ${\gamma}$-ray irradiated-polyethylene was higher than that of electron beam irradiated polyethylene.

• Journal of the Korean Chemical Society
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• v.48 no.2
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• pp.171-176
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• 2004

We investigated the activity and stability of alcohol oxidase from Hansenula sp. under the electric stimulation. The activity and stability of alcohol oxidase depended on electric output voltage, stimulation time, pulse duration and pulse interval. This inactivation of the enzyme under electric stimulation could be recovered by stabilizing additives such as sugars, polymers and hydrogels. The enzyme activity retained about 52% in 10% trehalose solution under electric stimulation with 40 V and 10 min. The stabilizing of enzymes against electric stimulation showed a great potential use of enzymes in biotechnology and medical engineering fields.

• Microbiology and Biotechnology Letters
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• v.12 no.4
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• pp.305-309
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• 1984

A selective medium which allows growth of only cellulolytic bacteria was developed. The medium composed of 0.5% carboxymethylcellulose (CMC), 0.005% yeast extract, minerals and agar. Colony formation on this medium indicates overall activities of cellulose utilization. A subsequent test with Congo Red dye could distinguish extracellular cellulolysis from intracellular type.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.3
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• pp.310-319
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• 2012

In order to investigate the biological effects of conformational changes in the folding state of bovine ${\alpha}$-lactalbumin (${\alpha}$-La), the protein was prepared and classified as apo form, microbial transglutaminase (MTGase) added form, or bovine ${\alpha}$-La made lethal to tumor cell (BAMLET) form. Apo ${\alpha}$-La form showed weaker cancer cell inhibitory activity (apoptosis) than native ${\alpha}$-La, which suggests that the metal ion-like $Ca^{2+}$ had a positive effect, whereas BAMLET form showed strong cancer cell apoptotic activity. The BAMLET form seemed to be a molten globule structure that increased hydrophobicity. MTGase added to apo ${\alpha}$-La polymer showed similar anti-cancer activity as native ${\alpha}$-La, and it was well hydrolyzed by digestive enzymes. NMR results showed that BAMLET interacted with oleic acid and produced a complex.

• Korean Journal of Food Science and Technology
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• v.38 no.2
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• pp.304-308
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• 2006

This study was performed to understand the behavior of protein mobility and intensity of enzymatic hydrolysis according to crosslinking of sodium caseinate, whey protein isolate, skim milk and whole milk powders with or without transglutaminase (TGase, w/w = 200 : 1) at $38^{\circ}C$. Whey protein was limited to crosslinking and skim milk was relatively more increased in high molecular polymer than whole milk. The degree of crosslinking decreased in the order of sodium caseinate>skim milk>whole milk>whey protein isolate. The SDS-PAGE results indicated that main bands of TGase treated samples had a high mobility and formed bands of molecular weights below 15 kDa by hydrolysis with pepsin after 10 min of reaction time. However, ${\beta}-lactoglobulin$ showed remarkable stability against pepsin hydrolysis treated with and without TGase. The high molecular polymers were easily hydrolyzed with digestive enzymes in vitro experiment. These results suggested that novel dairy products using TGase would have no special digestive problem in human body.