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가열속도에 따른 콘크리트 내부의 수분이동이 폭렬발생에 미치는 영향
최경철 ( Choe Gyeong-cheol ),김규용 ( Kim Gyu-yong ),남정수 ( Nam Jeong-soo ),김홍섭 ( Kim Hong-seop ),윤민호 ( Yoon Min-ho ),황의철 ( Hwang Ui-chul ) 한국건축시공학회 2017 한국건축시공학회 학술발표대회 논문집 Vol.17 No.1
In this study, it reviewed the effect of moisture migration in concrete with heating rate on concrete spalling. Concrete specimens with compressive strength 30MPa and 110MPa are used and its size is □100×100×h200mm. And, two kinds of heating rate are set such as IS0 834 and 1℃/min. As a result, in the concrete specimen exposed to ISO 834 standard heating condition, moisture could migrate through pore network and surface concrete pieces fall out by generating moisture clog near the surface in 110MPa concrete specimen. Meanwhile, In the case of concrete specimens exposed to 1℃/min. heating condition, it is appeared that moisture could not migrate because temperature is distributed uniformly. Therefore, surface spalling is not occurred with low heating rate. However, in the case of 110MPa concrete specimen is exploded even though it heated by low heating rate.
Flavonoids from the Leaves of Ailanthus altissima Swingle and their Antioxidant Activity
( Min Kyung Lee ),( Su Yeon Kim ),( Ji Hae Park ),( Do Gyeong Lee ),( Dae Young Lee ),( Geum Soog Kim ),( Yong Bum Kim ),( Dae Seok Han ),( Chang Ho Lee ),( Nam In Baek ) 한국응용생명화학회 2013 Journal of Applied Biological Chemistry (J. Appl. Vol.56 No.4
Phytochemical studies on the leaves of Ailanthus altissima (Simaroubaceae) have not been reported previously. Thus, the authors isolated and identified secondary metabolites from A. altissima. Dried and powdered leaves were extracted with 80% aqueous methanol, and the concentrated extract was successively partitioned with ethyl acetate, n-butanol, and water. Four flavonoids were isolated from the ethyl acetate fraction through repeated silica gel and octadecyl silica gel column chromatography. Spectroscopic data including NMR, MS, and IR allowed for identification of the chemical structures as quercetin (1), afzelin (2), quercitrin (3), and isoquercitrin (4). This is the first report of the isolation of these compounds from A. altissima. The four isolated flavonoids 1?4 as well as solvent fractions (ethyl acetate, n-butanol, and water), were evaluated for DPPH radical scavenging activity.