• 한국염색가공학회지
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• 제35권4호
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• pp.231-238
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• 2023

Microporous gel films of 29 m were prepared by the gel drawing of UHMWPE/soybean oil blend (4:6, w/w) up to 800%. The stretched films containing the optimal photoinitiator concentration, depending on the film thickness, was cross-linked under 365 nm LED-UV irradiation and the oil was extracted with n-hexane, resulting in a gel fraction of 95 % or more. With the formation of the cross-linked structure, the melt-down temperature and melt-down elongation increased by 16 ℃ and by 63% respectively. Also the thermal stability of the crosslinked UHMWPE was proved by the area shrinkage under the heat treatment decreased to 3.8 % compared to 17.4 % for the pristine film, and by the reductions in the combustion heat. The enhanced thermal stability of the crosslinked UHMWPE microporous membranes can be used for various industrial applications such as filters, electric vehicles and energy storage systems.

• Journal of Pharmaceutical Investigation
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• 제34권5호
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• pp.407-411
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• 2004

New formulations of amlodipine maleate tablet have been investigated to enhance the stability of the drug against light and humidity. Three kinds of amlodipine maleate tablets were prepared. One is prepared by previously known formulation (formulation C), the others were by new formulations using hydrophilic polymer $(Opadry^{\circledR})$ coated granules (formulations A and B). Amlodipine maleate powder was coated with $Opadry^{\circledR}$ to produce the coated granules and it was mixed with other excipients to produce the tabletting mass of new formulations A and B. Dissolution rate of newly formulated tablets was over 80% within 10 minutes in 0.01 M HCl medium, and its dissolution pattern was similar to that of $Norvasc^{\circledR}$ tablet. After 6 months storage under accelerated conditions, residual drug contents of tested formulations (A and B) were not significantly different from formulation C, ranging from 96.2 to 100.4%. Meanwhile, dissolution amount of formulation C was significantly reduced compared to that of formulation A (p<0.05), showing formulation A was more stable than unprotected formulation C at the accelerated conditions. Results of appearance, hardness and disintegration remained unchanged during stability study. In conclusion, it showed that the new formulations had enhanced the stability characteristics and hydrophilic coating technique was an alternative and promising method to improve the stability of amlodipine maleate tablet.

• 한국식품영양과학회지
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• 제39권3호
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• pp.414-420
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• 2010

저장성, 영양성 및 생리적 기능성을 가지는 두부를 제조하기 위하여 생리적 기능성이 널리 알려진 홍삼 추출물을 첨가하여 압착 성형 공정 없는 연두부의 형태로 제조하여 홍삼 추출물 첨가 연두부의 저장기간에 따른 저장성, 이화학적, 항산화 활성 변화 및 관능적 평가를 측정하였다. 홍삼 추출물을 첨가하지 않은 연두부 대조군의 pH 및 산도는 홍삼추출물 첨가 연두부와 큰 차이가 없었으며 저장기간에 따른 변화도 거의 없었다. 또한 일반세균수의 변화에 있어서도 대조군은 저장 10일차부터 약간의 일반세균이 발견되었으나 홍삼 추출물을 첨가하여 제조한 연두부는 대조군에 비하여 낮은 균수 또는 검출되지 않는 것으로 나타났으며 홍삼 추출물의 함량이 높을수록 항균효과가 있는 것으로 나타났다. 연두부의 색도는 명도 및 적색도는 홍삼 추출물 첨가에 따라 약간 감소하였고 황색도는 증가하였다. 연두부의 조직감은 홍삼 추출물 첨가 유무에 크게 관계가 없는 것으로 나타났다. 연두부의 지질과산화 억제능 및 DPPH radical 소거능은 대조군보다 홍삼 추출물을 첨가하여 제조하였을 때 억제능이 증가하였다. 관능검사 결과에서는 색에 대한 편견때문에 0.20% 이상의 홍삼 추출물 첨가군에서는 다소 낮은 기호도를 보였으나 0.18% 첨가군까지는 대조군과 큰 차이를 보이지는 않는 것으로 나타났다.

• Corrosion Science and Technology
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• 제15권5호
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• pp.209-216
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• 2016

In the present study, chitosan based self-healing anticorrosion coatings were prepared by layer by layer (lbl) addition of chitosan (Ch) and polyvinyl butyral (PVB) on mild carbon steel substrate. Chitosan coatings exhibited enhanced coating stability and corrosion resistance in aggressive environments by the application of a PVB top layer. Chitosan layer in the lbl coatings have been modified by using glutaraldehyde (Glu) and silica ($SiO_2$). Performance of different coatings was tested using electrochemical impedance spectroscopy and immersion test. The best anticorrosion performance was observed in case of 10 % Ch_$SiO_2$_PVB coatings, which withstand immersion test over 25 days in 0.5 M salt solution without visible corrosion. 10 % Ch_$SiO_2$ coatings without the PVB top layer didn't last more than 3days. Application of PVB top layer sealed the defects in the chitosan pre-layer and improved its hydrophobic nature as well. Raman spectra and SEM of steel surfaces after corrosion study and removal of PVB_Ch/Glu_PVB coatings showed a passive layer of iron oxide, attributing to the self-healing nature of these coatings. Conducting particle like graphene reinforcement of chitosan in the lbl coatings enhanced corrosion resistance of chitosan coatings.

• Macromolecular Research
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• 제10권4호
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• pp.187-193
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• 2002

Several methods have been used to synthesize polymer-clay nanocomposites. In-situ polymerization with clay belongs to a classical way to develop nano-structured materials, while melt intercalation is being recognized as another useful approach due to its versatility and environmentally benign character. In this research, we prepared polymer-clay nanocomposites based on the poly (methyl methacrylate) and organically modified montmorillonite via two-stage sonication process. According to the unique mode of power ultrasonic wave, the sonication during processing led to enhanced breakup of the clay agglomerates and reduction in size of the dispersed phase. Optimum conditions to form stable exfoliated nanocomposites were studied for various compositions and conditions. It was found that a novel attempt carried out in this study yielded further improvement in the mechanical performance of the nanocomposites compared to those produced by the conventional melt mixing process, as revealed by DMA, XRD and TEM. And rheological properties of nanocomposites were measured by ARES. As a result, sonicated PMMA-clay nanocomposites exhibits enhanced properties such as storage modulus and thermal stability than that of neat PMMA.

• Carbon letters
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• 제27권
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• pp.18-25
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• 2018

In this study, graphene oxide(GO) was used as drug carriers to amorphize poorly watersoluble drugs via a co-spray drying process. Two poorly water-soluble drugs, fenofibrate and ibuprofen, were investigated. It was found that the drug molecules could be in the graphene nanosheets in amorphous or nano crystalline forms and thus have a significantly enhanced dissolution rate compared with the counterpart crystalline form. In addition, the dissolution of the amorphous drug enwrapped with the graphene oxide was higher than that of the amorphous drug in activated carbon (AC) even though the AC possessed a larger specific surface area than that of the graphene oxide. The amorphous formulations also remained stable under accelerated storage conditions ($40^{\circ}C$ and 75% relative humidity) for a study period of 14 months. Therefore, graphene oxide could be a potential drug carrier and amorphization agent for poorly water-soluble drugs to enhance their bioavailability.

• Food Science and Biotechnology
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• 제17권4호
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• pp.794-798
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• 2008

Guar gum and $\kappa$-carrageenan were investigated as a substitutes for phosphate in pork meat processing. Emulsion-type pork sausages were prepared in which 0.5% phosphate was used for the control, and either $\kappa$-carrageenan or guar gum were added at levels of 0.1 or 0.5% for comparison. The hydrocolloid compounds significantly enhanced water holding capacity and cooking loss. However, hardness, cohesiveness, and chewiness were not well-maintained when compared to the control; this was attributable to the altered water distribution as well as enhanced water holding capacity of the sausages by the addition of $\kappa$-carrageenan and guar gum. Furthermore, the phosphate-free sausages had similar storage stability as the phosphate-added sausage. Overall, the results suggest that $\kappa$-carrageenan or guar gum can be used in place of phosphate in conventional processing to successfully prepare phosphate-tree pork sausages.

• 한국세라믹학회지
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• 제56권1호
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• pp.65-70
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• 2019

Simple fabrication of a powdered Ge-reduced graphene oxide (Ge-rGO) composite via spray pyrolysis and reduction is introduced herein. Successful incorporation of the rGO nanosheets with Ge hindered the aggregation of Ge and conferred enhanced structural stability to the composite by alleviating the mechanical stress associated with drastic volume changes during repeated cycling. The Li-ion storage performance of Ge-rGO was compared with that of powdered Ge metal. The reversible discharge capacity of Ge-rGO at the $200^{th}$ cycle was $748mA\;h\;g^{-1}$ at a current density of $1.0A\;g^{-1}$ and Ge-rGO showed a capacity of $375mA\;h\;g^{-1}$ even at a high current density of $5.0A\;g^{-1}$. The excellent performance of Ge-rGO is attributed to the structural robustness, enhanced electrical conductivity, and formation of open channels between the rGO nanosheets, which facilitated electrolyte penetration for improved Li-ion diffusion.

• Asian-Australasian Journal of Animal Sciences
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• 제14권3호
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• pp.365-371
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• 2001

The effects of light exposure and light intensity on surface color of Hanwoo (Korean native cattle) beef and color stability of fresh normal and DFD (dark, firm, dry) muscles during 7 days at $4{\pm}1^{\circ}C$ under three display conditions (Dark, Light1000 and Light3000) were investigated. The $L^*$, $a^*$, $b^*$, $C^*$ values and R630-R580 were significantly (p<0.05) higher in normal beef than in DFD beef. The $a^*$, $b^*$, $c^*$ values and R630-R580 of normal beef increased during the first day of display except Light3000 group, then gradually decreased over time. The surfaces of Hanwoo beef accumulated more metmyoglobin in the light than in the dark. Also, the rate of decrease in redness during refrigerated storage was enhanced by light exposure and increase in light intensity. Discolorations were more rapid in DFD beef than normal beef. Increasing light intensity promoted not only discoloration but also lipid oxidation. Therefore storage in the dark is effective in retarding the formation of a brown color in Hanwoo beef.

• 한국식품과학회지
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• 제30권4호
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• pp.733-738
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• 1998

Copigment로서 tannic aicd, caffeic acid, chlorogenic acid를 선택하여 유색미 안토시아닌의 색변화 특성 및 온도, 금속이온, 빛에 대한 안정성 변화를 조사하였다. 안토시아닌과 copigment 농도(M)비율을 1:1, 1:5, 1:10, 1:20과 1:40으로 조정하여 copigmentation 효과를 조사한 결과, copigments농도가 높을수록 농색화 효과가 높았으며, tannic acid를 첨가한 실험군이 가장 높은 농색화 효과를 나타내었다. $25^{\circ}C$에서 21일간 저장시에도 tannic acid의 농색화 효과는 지속적으로 유지되어 대조군에 비해 높은 안정성을 보여주었다. 고온에서는 copigment 첨가군의 반감기가 대조군의 반감기보다 감소하여 열에 대하여 오히려 더 불안정한 것으로 나타났다. Tannic acid와 금속이온을 함께 첨가한 경우에는 금속이온에 의한 농색화와 함께 copigment에 의한 농색화도 동시에 일어나 안정화 효과가 높아졌다. Copigmentation에 의하여 빛에 의한 안토시아닌의 분해속도가 크게 감소하여 빛에 대한 안정화 효과가 관찰되었다.