• Fibers and Polymers
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• v.7 no.4
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• pp.372-379
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• 2006

The surface topography, tensile properties, and thermal properties of ramie fibers were investigated as reinforcement for fully biodegradable and environmental-friendly 'green' composites. SEM micrographs of a longitudinal and cross sectional view of a single ramie fiber showed a fibrillar structure and rough surface with irregular cross-section, which is considered to provide good interfacial adhesion with polymer resin in composites. An average tensile strength, Young's modulus, and fracture strain of ramie fibers were measured to be 627 MPa, 31.8 GPa, and 2.7 %, respectively. The specific tensile properties of the ramie fiber calculated per unit density were found to be comparable to those of E-glass fibers. Ramie fibers exhibited good thermal stability after aging up to $160^{\circ}C$ with no decrease in tensile strength or Young's modulus. However, at temperatures higher than $160^{\circ}C$ the tensile strength decreased significantly and its fracture behavior was also affected. The moisture content of the ramie fiber was 9.9 %. These properties make ramie fibers suitable as reinforcement for 'green' composites. Also, the green composites can be fabricated at temperatures up to $160^{\circ}C$ without reducing the fiber properties.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1621-1623
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• 1999

Recently, high voltage outdoor ploymer insulators have been widely used commercially owing to their excellent electrical and mechanical properties, superior comtamination flashover performance, light weight, easy installation or handing, no maintenance during service, competitive price and so on. compared to porcelaain and glass insulators. For instance, silicone rubber(SR) for polymeric insulators specially has much superior insulating and anti-pollution performance due to its specific hydrophobicity even in severe contaminated environments. We have investigated surface discharge current characteristics of silicone rubbers(SR) for HV outdoor composite insulation specimen under accelerated aging codition using a computer measuring system. The relations of average leakage current and surface discharge current repetition rates and discharge current amplitude, the distribution of discharge current amplitude were studied to investigate electrical conduction of silicone rubber surface with the salt fog condition.

• Preventive Nutrition and Food Science
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• v.22 no.3
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• pp.241-245
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• 2017

Aged garlic has been reported to possess beneficial pharmacological activities, including anti-stress and anti-fatigue properties, and to exert protective effects on the cardiovascular system and liver. Pine needles are widely used in folk medicine and as food additives owing to their pharmacological properties such as anti-aging and anti-inflammatory effects. It has long been known that combining certain phytochemicals with other phenols or organic acids can produce synergistic effects. Therefore, the purpose of this study was to develop an optimal formula of aged garlic with added pine needle powder for improved antioxidant activity using the statistical technique of response surface methodology. The antioxidant activities of aged garlic mixed with pine needle powder were confirmed by measuring oxygen radical absorbance capacity and total polyphenol content. An optimized antioxidant formula was identified that contained 5.08 g aged garlic and 1.97 g pine needle powder. The antioxidant activities of the mixture prepared using this optimal formula were significantly higher than the predicted values according to an additive model. Hence, this study confirms that the addition of pine needle powder to aged garlic can improve its antioxidant activity. This study demonstrated an optimal mixing ratio to produce an aged garlic product with improved functionality through the addition of pine needle powder that could be successfully employed by the food industry to prepare functional foods.

• Transactions of Materials Processing
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• v.13 no.1
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• pp.53-58
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• 2004

The microstructural changes of Al-Zn-Mg-Cu alloy containing Sc during hot extrusion and post heat treatment were investigated. Two kinds of Al-Sc alloys with different alloying elements (B1, B2) were hot extruded to make T-shape bars at extrusion temperature of $380^{\circ}C$, then the bars were solution treated at $480^{\circ}C$ for 2hrs followed by artificial aging at $120^{\circ}C$ for 24hrs. The interior microstructure of as extruded bar consisted of elongated grains, however, fine equiaxed grains were also observed around surface. The microstructural gradient suggested that different restoration process could proceed during the hot extrusion. For B1 and B2, different grain growth behaviors were found around the surface during the post heat treatment. Rapid grain growth behavior was observed for B1 around the surface, however, it was not observed for B2. Orientation pinning, which was related with the evolution of preferred orientation, and precipitation were thought to be responsible for the rapid grain growth.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.3
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• pp.446-453
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• 1995

The improtant components of extracellular matrix(ECM) are collagen and chondroitin sulfate. The hydrophobic surface of collagen is one of the determining factors of diameter of collagen fiber and also is closely related to the aging phenomena. The controlling mechanism of the diameter of collagen fiber influenced by the interaction with chondroitin sulfate was evaluated using bis-ANS as a hydrophobic probe. Hydrophobic surface area of collagen molecule shielded by chondroitin sulfate was evaluated. Relative fluorescence intensity of collagen in thepresence of chondroitin sulfate was measured using bis-ANS as a hydrophobic probe. The fluorescence intensity decreased with the increase in chondroitin sulfate up to 3.8 chondroitin sulfate/collagen(mole/mole). Further increase in the ratio of chondroitin sulfate to collagen did not change the fluorescence intensity. Similar changes in the relative fluorescence intensity were observed for both rat tail and lathyrific rat skin collagen. The fluorescence intensity indicated by the binding between bis-ANS and hydrophobic sites of collagen was pH dependent, and the shielding effect of collagen-chondroitin sulfate interaction could not be detected at pH above 6.0. This is probably due to the charge repulsions caused by negative charged collagen molecules at higher pH.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.563-566
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• 2003

The conventional testing as IEC-60587 is widely used in suface aging measurement of outside insulator those testing can carry out very short time in Lab testing. Also IEC-60587 testing is able to offer the standard judgement of relative degradation level of out side HV machine. Therefore it is very useful method compare to previous conventional tracking testing method and effective Lab testing method, But surface discharges(SD) have very complex characteristics of discharge pattern so it is required estimation research to development of precise analysis method. In recent, the study of IRR Camera is carrying out discover of temperature of power equipment through condition diagnosis and system development of degradation diagnosis.

• Corrosion Science and Technology
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• v.17 no.6
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• pp.257-264
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• 2018

Anti-graffiti coatings have become more important. These layers must guarantee excellent corrosion protection properties, and graffiti must be easily removable, without reducing protection and aesthetic properties. In this study, anti-graffiti and corrosion behavior of two anti-graffiti polyurethane powder coatings were studied. These layers were deposited on aluminum substrate, with two different surface finishes, smooth, and wrinkled. The action of four different removers are investigated. Graffiti were drawn on coatings by means of red acrylic spray paint. Methyl-ethyl-ketone (MEK) and a "commercial" remover were the most effective solvents, in terms of graffiti removal capability, producing limited change in aesthetical surface aspect for smooth finishing. The wrinkled surface was less resistant. Corrosion protection properties, after removal action and contact with the remover, were evaluate by electrochemical impedance spectroscopy. After approximately 5 hours, coatings were no longer protective due to formation of defects. To simulate the weathering effect, UV-B cyclic test (4 hours of UV exposure followed by 4 hours of saturated humidity at $50^{\circ}C$) were performed for 2000 hours. Gloss and color changes were measured, and electrochemical impedance spectroscopy measurements were performed after aging and graffiti removal.

• Journal of Life Science
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• v.24 no.2
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• pp.167-172
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• 2014

Optimal conditions for extraction of bakkenolide B from Petasites japonicus leaves were determined by using response surface methodology. A second-order Box-Behnken design representing three extraction temperatures (80, 100, $120^{\circ}C$), three extraction times (30, 45, 60 min), and three solvent pH's (5, 7, 9) was executed. The efficiency of the extraction conditions was defined using the ${\beta}$-hexosamidase assay by comparing both the bakkenolide B content and its anti-allergic activity expressed as extract inhibition on degranulation. The response surface plot described for the bakkenolide B content showed that the maximum content was predicted as 121.6 ${\mu}g/g$ with extraction conditions of $127.1^{\circ}C$, 46.6 min, and pH 7.7. Extraction temperature and time were important factors in determining bakkenolide B content. Using regression analysis, correlation between the inhibition effect of mast cell degranulation and bakkenolide B content was found to be low.

• The Journal of the Petrological Society of Korea
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• v.28 no.4
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• pp.227-236
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• 2019

Medium to coarse-grained biotite granodiorite was used to build the Standing Buddha Statue in the Gwanchoksa temple. An ancient document revealed the period and place of constructing the statue: it was made in the northwest of Mt. Banyasan and then moved eastward. Also, the comparison of standing Buddha statue and basement rock in terms of texture, magnetic susceptibility, and gamma spectrometer shows that they have similar characteristics, which is considered to be the same provenance rock. The damage caused by surface contaminants observed in the statue seems to be a combined effect of environmental factors and aging of the epoxy resin. After removal of the contaminants in 2007, the contamination has resumed, and continuous monitoring is necessary. Algal engraftment becomes faster when biological contamination occurs on the surface of stone cultural heritage. Since the secondary lichen growth forms a symbiosis with mold, it is necessary to observe the spatial and distributional changes. Also, the aging epoxy resin may cause secondary damage due to contaminants generated due to the determination of salts, and deterioration of bonding strength due to breaking out. Thus it is desirable to secure stability through proper conservation management.

• Journal of Life Science
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• v.30 no.8
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• pp.722-730
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• 2020

As one of the most serious health risk factors, air pollution can no longer be ignored. Particulate matter (PM) is an important and harmful component of air pollution that originates from a variety of sources. Numerous recent studies have linked PM to a range of conditions including cancer, cardiovascular, respiratory, and skin disease. The eye, despite being directly exposed to air pollution, has been investigated in very few of these studies. In this review, we describe the evidence from in vitro and in vivo studies, as well as epidemiological investigations, that supports the association between exposure to PM and the development of ocular conditions such as surface and retinal disease and glaucoma. Based on the results of previous studies, we suggest that PM exposure can lead to oxidative stress, inflammation, autophagy, and, ultimately, ocular surface disease. Nevertheless, almost no studies focus on ocular surface damage from PM while some epidemiological and clinical studies report on the posterior of the eye. However, the underlying pathological mechanisms in the posterior following PM exposure have yet to be identified, and further studies are therefore warranted of the ocular surface as well as the posterior part of the eye.