• 한국식품영양과학회지
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• 제36권6호
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• pp.657-662
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• 2007

본 연구는 약쑥(Artemisia princeps Pamp) 추출물의 항산화 효능을 조사하고자, 약쑥 분획물을 이용하여 총 폴리페놀 및 플라보노이드 함량, 활성산소종 소거능 및 간 microsome을 이용한 지질과산화 억제효과 등을 관찰하였다. 약쑥의 폴리페놀 함량 및 플라보노이드 함량은 EtOAc층에서 각각 $311.35{\mu}g/mg$ 및 $92.73{\mu}g/mg$으로 가장 높게 나타났다. DPPH radical 소거능은 EtOAc층의 $IC_{50}$이 $52.71{\mu}g/mg$으로 분획물 중에서 가장 높은 소거능을 보였다. Superoxideanion의 소거능은 EtOAc층의 $IC_{50}$은 $26.47{\mu}g/mg$으로, 합성항산화제인 BHA($IC_{50}:\;49.78{\mu}g/mg)$ 보다 항산화 효과가 우수한 것으로 나타났다. Hydrogen peroxide 소거능은 n-BuOH층의 $IC_{50}$이 $166.44{\mu}g/mg$으로, BHA의 소거활성보다 유의적(p<0.05)으로 높음을 알 수 있었다. Hydroxyl 라디칼 소거능도 EtOAc층의 $IC_{50}$값이 $58.92{\mu}g/mg$으로, BHA($IC_{50}:\;80.85{\mu}g/mg)$보다 유의적(p<0.05)으로 높았다. NO 소거능은 EtOAc층의 $IC_{50}$이 $65.94{\mu}g/mg$으로, BHA와 유의적인 차이가 없었다. 간 microsome에서의 지질과산화 억제효과도 EtOAc층이 분획물 중에서 가장 우수하였다. 이상의 결과로부터 약쑥 분획물의 EtOAc층이 총 폴리페놀 및 플라보노이드 함량이 높음을 알 수 있었으며, 이에 따른 활성산소종 소거능 및 간 microsome을 이용한 지질과산화 억제효과도 관찰할 수 있었다.

• 폴리머
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• 제37권1호
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• pp.61-65
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• 2013

본 실험에서는, 양극산화 처리된 탄소섬유의 표면변화가 탄소섬유강화 복합재료의 기계적 계면특성을 통하여 살펴보았다. 양극산화 처리된 탄소섬유의 표면특성은 FTIR, XPS, 그리고 SEM을 통하여 알아보았다. 복합재료의 기계적 계면특성은 층간전단강도(interlarminar shear strength; ILSS)와 임계세기인자(critical stress intensity factor; $K_{IC}$) 그리고 임계변형속도에너지(critical strain energy release rate; $G_{IC}$)를 통하여 고찰하였다. 실험결과 양극산화에 의한 각각의 표면 처리된 탄소섬유는 표면특성의 변화를 가져오며, 복합재료의 ILSS, $K_{IC}$, 그리고 $G_{IC}$같은 기계적 계면특성은 탄소섬유의 양극산화를 통하여 향상되어진다. 전해질이 20% 황산/질산(3/1)일 때 다른 전해질보다 기계적 물성의 가장 큰 향상을 보였다. 이는 양극산화로 탄소섬유와 매트릭스 사이의 계면결합력의 향상때문이라 판단된다.

• Journal of Microbiology and Biotechnology
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• 제27권1호
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• pp.155-160
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• 2017

The dye decolorization rate in a cell-free culture broth of the white-rot fungus Trametes versicolor CBR43 was studied, including the effects of inhibitors of NaCl, Zn(II), and Cd(II) on dye decolorization activity. The maximum rates of dye decolorization in cell-free culture broth were 1,410, 44.7, 41.2, and $0.19{\mu}mol{\cdot}l^{-1}{\cdot}min^{-1}$ for Acid Blue 62, Acid Black 175, Reactive Blue 4, and Acid Red 114, respectively. The inhibition effects of NaCl, Zn(II), and Cd(II) on dye decolorization were quantitatively compared using the half maximal inhibition concentration ($IC_{50}$), which indicates the concentration of an inhibitor required for 50% inhibition. Based on $IC_{50}$ values, dye decolorization in the cell-free culture broth of CBR43 was most potently inhibited by Cd(II), whereas the inhibitory effect of NaCl was relatively low. The dye decolorization rates and $IC_{50}$ data can be used in the design and development of a dye-wastewater treatment process using T. versicolor CBR43 and its operating factors.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2001년도 학술대회 논문집
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• pp.29-32
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• 2001

Internal tin processed Nb$_3$Sn wires of intermediated worked state of were took from Mitsubishi and fabricated with various diameters ranging from 0.76 mm to 0.2 mm. These specimens were heat-treated at $460^{\circ}C$ for 70 h and at $570^{\circ}C$ for 100h to form bronze and at $700^{\circ}C$ for 100h to form Nb$_3$Sn compound. Bending strain Ic s of the wires were measured with various bending diameters ranging from flat to 76 mm. In order to investigate the sensitivity for strain, small diameters of wires were strain Ic at 6 T, 4.2 K. There were no breakage decrease during cold working to 0.2 mm of diameter and no decrease Jc to the diameter of 0.3 mm. The values of bending strain Ic of 0.2 mm and 0.3 mm diameters of the wires were not decreased at 76 mm of bending diameter.

• Carbon letters
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• 제20권
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• pp.39-46
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• 2016

In this work, the effects of maleic anhydride (MA) content on mechanical properties of chopped carbon fibers (CFs)-reinforced MA-grafted-polypropylene (MAPP) matrix composites. A direct oxyfluorination on CF surfaces was applied to increase the interfacial strength between the CFs and MAPP matrix. The mechanical properties of the CFs/MAPP composites are likely to be different in terms of MA content. Surface characteristics were observed by scanning electron microscope, Fourier transform infrared spectroscopy, and single fiber contact angle method. The mechanical properties of the composites were also measured by a critical stress intensity factor (K_IC). From the K_IC test results, the K_IC values were increased to a maximum value of 3.4 MPa with the 0.1 % of MA in the PP, and then decreased with higher MA content.

• Preventive Nutrition and Food Science
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• 제20권1호
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• pp.67-72
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• 2015

Squid is one of the most important commercial fishes in the world and is mainly utilized or consumed as sliced raw fish or as processed products. The biofunctional activities of enzymatic squid meat hydrolysate were determined to develop value-added products. Enzymatic squid hydrolysate manufactured by Alcalase effectively quenched 1,1-diphenyl-2-picrylhydrazyl radical, hydroxyl radical, and hydrogen peroxide radical with $IC_{50}$ values of 311, 3,410, and $111.5{\mu}g/mL$, respectively. Angiotensin I-converting enzyme inhibitory activity of squid hydrolysate was strong with an $IC_{50}$ value of $145.1{\mu}g/mL$, while tyrosinase inhibitory activity with an $IC_{50}$ value of 4.72 mg/mL was moderately low. Overall, squid meat hydrolysate can be used in food or cosmetic industries as a bioactive ingredient and possibly be used in the manufacture of seasoning, bread, noodle, or cosmetics.

• Journal of Mechanical Science and Technology
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• 제16권2호
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• pp.147-154
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• 2002

The objective of this paper is to develop a nondestructive method for estimating the fracture toughness (K$\_$IC/) of CrMoV steels used as the rotor material of steam turbines in power plants. To achieve this objective, a number of CrMoV steel samples were heat-treated, and the fracture appearance transition temperature (FATT) was determined as a function of aging time. Nonlinear ultrasonics was employed as the theoretical basis to explain the harmonic generation in a damaged material, and the nonlinearity parameter of the second harmonic wave was the experimental measure used to be correlated to the fracture toughness of the rotor steel. The nondestructive procedure for estimating the 7c consists of two steps. First, the correlations between the nonlinearity parameter and the FATT are sought. The FATT values are then used to estimate K$\_$IC/, using the K$\_$IC/ versus excess temperature (i.e., T-FATT) correlation that is available in the literature for CrMoV rotor steel.

• Archives of Pharmacal Research
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• 제28권9호
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• pp.1053-1056
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• 2005

Cytotoxic activitiy of seven hederagenin saponins isolated from the root of Dipsacus asper were investigated in vitro against L1210, HL-60 and SK-OV-3 tumor cell lines by the MTT method. $3-O-\alpha-L-rhamnopyranosyl-(1{\rightarrow}2)-\alpha-L -arabinopyranosyl$ hederagenin (2),\;$3-O-\beta-D­xylopyranosyl-( 1{\rightarrow}3)-\alpha-L-Rhamnopyranosyl-(1{\rightarrow}2)-\alpha-L -arabinopyranosyl$ hederagenin (6) and $3-O-\beta-D-glucopyranosyl-(1{\rightarrow}3)-\alpha-L-rhamnopyranosyl-( 1{\rightarrow}2)-\alpha-L-arabinopyranosyl$ hederagenin (7) exhibited the potent cytotoxicity against the three tumor cell lines with $IC_{50}$ values ranging from 4.7 to 8.7 ${\mu}g/mL$, with the exception of compound 7, which exhibited weak cytotoxic activity against SK-OV-3 $(IC_{50}\;22.5\;{\mu}g/mL)$. Other compounds did not exhibit any cytotoxic activity $(IC_{50}>30{\mu}g/mL)$.

• Archives of Pharmacal Research
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• 제29권12호
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• pp.1119-1124
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• 2006

The methanol extract from the aerial parts of Dictamnus albus was active in inhibiting monoamine oxidase (MAO) from the mouse brain. Activity-guided fractionation led to the isolation of four known coumarins, 7-(6'R-hydroxy-3', 7'-dimethyl-2'E, 7'-octadienyloxy) coumarin (1), auraptene (2), umbelliferone (3), and xanthotoxin (4), as active compounds along with an inactive alkaloid, skimmianine (5). Compounds 1 and 2 inhibited MAO activity in a concentration-dependent manner with $IC_{50}$ values of 0.7 and $1.7\;{\mu}M$, respectively. Compounds 1 and 2 showed a slight and potently selective inhibitory effect against MAO-B ($IC_{50}\;0.5\;and\;0.6\;{\mu}M,\;respectively$) compared to MAO-A ($IC_{50}\;1.3\;and\;34.6\;{\mu}M,\;respectively$). According to kinetic analyses derived by Lineweaver-Burk reciprocal plots, compounds 1 and 2 exhibited a competitive inhibition to MAO-B.

• 한국주조공학회지
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• 제16권2호
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• pp.109-115
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• 1996

Effect of various austempered structures on fracture characteristics of C/V graphite cast iron has studied. The tensile strength and hardness reached the maximum value of 971.4MPa and HB302 at the austempering temperature of $250^{\circ}C$, respectively. As the austempering temperature increased, the amount of retained austenite increased from 18% to 22, 29%, while $K_{IC}$ values ranged from the value of $65MPa{\cdot}m^{12} to 70MPa{\cdot}m^{1/2}, 66MPa{\cdot}m^{1/2}. This fact that $K_{IC}$ value was not sensitive to the increase of the amount of the retained austenite was that $K_{IC}$ was dependent on the matrix structure in lower bainitic matrix, while dependent on the notch effect from C/V graphite shape in upper bainitic matrix. Fractured surfaces showed a ductile fracture pattern at $300^{\circ}C$. Very large coalescence by C/V graphite and relatively small voids by spheroidal graphite were observed.