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김수철(Su Cheol Kim),권현숙(Hyun Sook Kwon),김철환(Chul Hwan Kim),김혜수(Hye Soo Kim),이창윤(Chang Yun Lee),조수정(Soo Jeong Cho) 한국생명과학회 2016 생명과학회지 Vol.26 No.8
본 연구에서는 천연물 유래 항산화 소재로서 흰색 느티만가닥버섯(Hypsizygus marmoreus)의 부위별 이용 가능성을 알아보기 위하여 흰색 느티만가닥버섯을 갓(pileus)과 대(stipe)로 분리하여 열수와 80% 에탄올에 침지한 다음 부위별 항산화 활성을 조사하였다. 흰색 느티만가닥버섯은 에탄올 추출물(갓 부위 923.47±0.18 mg GAE/100g, 대 부위 324.05±0.03 mg GAE/100 g)에 비해 열수 추출물(갓 부위 1137.39±0.38 mg GAE/100 g, 대 부위 700.86±0.06 mg GAE/100 g)의 총 폴리페놀 함량이 높게 나타났고 대 부위보다는 갓 부위의 총 폴리페놀 함량이 높게 나타났다. DPPH 라디칼 소거 활성은 10 mg/ml의 농도에서 에탄올 추출물 갓 부위의 활성이 47.32±0.23%로 가장 높았으며 ABTS 라디칼 소거 활성도 10 mg/ml의 농도에서 에탄올 추출물 갓 부위의 활성이 57.33±0.10%로 가장 높았다. 환원력과 ORAC 지수는 에탄올 추출물에 비해 열수 추출물이 높게 나타났고 환원력은 갓 부위와 대 부위에 큰 차이가 없었으나 ORAC 지수는 대 부위보다는 갓 부위가 높게 나타났다. 흰색 느티만가닥버섯 추출물의 세포 독성은 WST-1 assay를 이용하여 추출물이 RAW 264.7 세포에 미치는 영향으로 평가하였다. 이상의 결과를 종합해보면, 흰색 느티만가닥버섯의 총 폴리페놀 함량과 항산화 활성은 추출물의 농도가 증가함에 따라 증가하는 경향을 나타내었으며 대 부위보다는 갓 부위의 항산화 활성이 우수하였다. Hypsizygus marmoreus (white cultivar), also called white beech mushrooms, are edible mushrooms commercially cultivated in Korea and Japan. This study was carried out to evaluate the antioxidant properties of H. marmoreus. H. marmoreus fruit bodies were divided into pileus and stipe. The pileus and stipe were extracted into water and 80% ethanol and their antioxidant activities were analyzed. The total polyphenol content was highest in the water extract (pileus 1137.39±0.38 mg of GAE (gallic acid equivalents)/100 g, stipe 700.86±0.06 mg of GAE/100 g) compared to the ethanol extract (pileus 923.47±0.18 mg of GAE/ 100 g, stipe 324.05±0.03 mg of GAE/100 g). Ethanol extracts from pileus showed better scavenging ability on DPPH (47.32±0.23% at 10 mg/ml) and ABTS (57.33±0.10% at 10 mg/ml) than the stipe and water extract groups. Water extract from pileus were more effective in reducing power and ORAC (oxygen radical absorbance capacity) value than stipe and ethanol extract. The toxicity of water and ethanol extracts was investigated using WST-1 (Water Soluble Tetrazolium salt) assay on the mouse macrophage cell line RAW 264.7. Overall, total polyphenol content and antioxidant activities of extracts from H. marmoreus increased in a dose dependent manner while pileus was showed better total polyphenol content and antioxidant activities than stipe.
PMDC 전동기의 접촉저항을 고려한 특성해석 및 파라미터 계측방법
김수철(Su-Chul Kim),김규식(Kyu-Sik Kim),김규섭(Kyu-Seob Kim),이봉현(Bong-Hyun Lee),이병화(Byeong-Hwa Lee) 한국자기학회 2018 韓國磁氣學會誌 Vol.28 No.5
Permanent magnet direct current motor (PMDC) has been widely used in industrial, automotive, and home applications because of simple structures, advantage of price and easy controllability. However, brush contact resistance is difficult to measure if the DC motor is not disassembled. In this paper, Characteristics analysis and measurement of motor parameters are treated about PMDC motors. For analyzing this method, the parameter model is conducted to measure the brush contact resistance. Finally, analysis values are compared to test result to verify the method.
생체온도에서 전기화학증착법을 이용한 티타늄 상 수산화인회석 코팅 연구
김수철(Su-Chul Kim),황문진(Moon-Jin Hwang),이운영(Woon-Young Lee),박영준(Yeong-Joon Park),송호준(Ho-Jun Song) 대한치과재료학회 2018 대한치과재료학회지 Vol.45 No.3
In this study, hydroxyapatite (HAp) was coated on titanium using electrochemical deposition (ECD) method at body fluid temperature. The titanium specimens for ECD were prepared by chemically etching treatment using 5M NaOH solution. The electrolyte mixed with 5 mM Ca(NO₃)₂ and 2 mM NH₄H₂PO₄ which has pH 5 (E2) was adjusted to pH 3 (E1) and pH 6 (E3). The different electric pulses of –10, -15, -30 mA were applied to each specimen. The temperature of electrolytes was kept at 37℃. E1-10, E1-15, E1-30, E2-10, E2-15, E2-30, E3-10, E3-15, and E3-30 groups were prepared for this study. Scanning electron microscope (SEM) images showed that E1-10 and E1-15 groups were not coated and the powder-shaped compounds were formed on E3-15 and E3-30 groups. The cracks were observed on the surface of E1-30 and E2-30 groups. The evenly and stable coated layer was deposited on E2-10, E2-15 and E3-10 groups. The layer coated on titanium surface had an HAp crystalline structure. E1-30 and E2-30 groups had low crystallinity, even though they had thick layer. HAp layer on for E2-10 group was well deposited on the surface because it more aligned to c-axis compared with other groups.
고주파유도가열 연소합성에 의한 나노구조 ReSi<sub>1.75</sub> 제조 및 기계적 성질
김병량,김수철,손인진,Kim, Byung-Ryang,Kim, Su-Chul,Shon, In-Jin 한국분말야금학회 2009 한국분말재료학회지 (KPMI) Vol.16 No.1
Nanostructured $ReSi_{1.75}$ was synthesized to have high density via rapid and cost effective process named as high-frequency induction heated combustion synthesis(HFIHCS) method. For the process, mechanically activated Re-Si powder was used, which had been prepared by mechanical ball milling of Re and Si powders with mixing ratio of 1:1.75. Both combustion synthesis and densification were accomplished simultaneously by applying electric current and mechanical pressure of 80 MPa during the process. The average grain size, hardness, and fracture toughness of the compound were 210 nm, 1085 $kg/mm^2$ and 4 $MPa{\cdot}m^{1/2}$, respectively. The experimental results show that HFIHCS is a promising process for synthesis of nanostructured $ReSi_{1.75}$ which has a potential for both high temperature and thermo-electric applications.