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구민성,김윤희,여남회 東亞大學校附設스포츠科學硏究所 2001 스포츠科學硏究論文集 Vol.19 No.-
The purpose of this study was to investigate literature study of the effect of antioxidant during exercise. The study material were five journal of exercise science, master and doctoral theses, and antioxidants. Total thirty-five articles were selected this study. This study demonstrated that the mechanism of free radical and antioxidant did not find out during exercise and recovery. High intensity exercise or training produced on excess of free radical, but low-intensity exercise and antioxidant supplement were not. These results suggest that don’t forget Cooper’s advices: “Exercise must be at the center of any effective antioxidant action plan.” The reason; without regular exercise, your body’s internal defense against free radicals including natural endogenous antioxidants like SOD, GSH, Catalase may become too fragile for supplement to have their full effect.
Byeong Cheol Min,Bon Wook Koo,Ki Seob Gwak,Hwan Myeong Yeo,Joon Weon Choi,In Gyu Choi 한국목재공학회 2011 목재공학 Vol.39 No.2
In this study, dilute acid pretreatment of Liriodendron tulipifera was performed for enzymatic hydrolysis. As the pretreatment temperature was increased, enzymatic hydrolysis and enzyme adsorption yield also increased. The highest enzymatic hydrolysis yield was 57% (gig) and enzyme adsorption was 44% (gig). Enzymatic hydrolysis yield was determined with weight loss of pretreated biomass by enzyme, and enzyme adsorption was a percentage of enzyme weight attaching on pretreated biomass compared with input enzyme weight. When L. tulipifera was pretreated with 1% sulfuric acid at 160℃ for 5 min., hemi-cellulose was significantly removed in pretreatment, but the lignin contents were constant. Other changes in surface morphology were detected on biomass pretreated at 160℃ by a field emission scanning electron microscope (FESEM). A large number of spherical shapes known as lignin droplets were observed over the entire biomass surface after pretreatment. Hemicellulose removal and morphological changes improved enzyme accessibility to cellulose by increasing cellulose exposure to enzyme. It is thus evidence that enzyme adsorption is a significant factor to understand pretreatment effectiveness.
Koo, Bon-Wook,Kim, Ho-Yong,Park, Nahyun,Lee, Soo-Min,Yeo, Hwanmyeong,Choi, In-Gyu Elsevier 2011 Biomass & bioenergy Vol.35 No.5
<P><B>Abstract</B></P><P>An acid-free organosolv process was proposed to overcome the problems caused by acid catalyst in organosolv process, thereby producing ethanol from <I>Liriodendron tulipifera</I> effectively. Although relative lignin contents were above 20%, enzymatic conversion increased significantly to 65% at all conditions, and thus correlation between lignin and enzymatic conversion could not be explained using relative lignin content. Enzymatic conversion increased significantly above 65% regardless of temperature, which suggests the organosolv pretreatment with sodium hydroxide can be performed at lower temperature. FE-SEM showed that the process made the structure loose and broke down biomass through lignin dissolution. Wrinkle formation by alkaline swelling was also observed and it might increase surface area. Although pore-volume increased slightly, it was not the sole key factor for the organosolv pretreatment with sodium hydroxide. Increase in surface area and enzyme adsorption enhanced the enzymatic hydrolysis. Ethanol of 96% could be produced theoretically and it suggested that the acid-free organosolv process was an effective pretreatment method for bioethanol production from <I>L. tulipifera</I>.</P> <P><B>Highlights</B></P><P>► An acid-free organosolv pretreatment using an alkaline catalyst. ► Enhancement in enzymatic hydrolysis through increase in surface area and enzyme adsorption. ► Theoretical ethanol production yield of 96% from <I>Liriodendron tulipifera</I> using the organosolv pretreatment with sodium hydroxide.</P>
Koo, B.W.,Min, B.C.,Gwak, K.S.,Lee, S.M.,Choi, J.W.,Yeo, H.,Choi, I.G. Pergamon ; Elsevier Science Ltd 2012 Biomass & bioenergy Vol.42 No.-
Although organosolv pretreatment removed substantial amounts of lignin and xylan, the yield of glucan which is a major sugar source for fermentation to ethanol is more than 90% in most conditions of the organosolv pretreatment. Relative lignin contents of all pretreated biomass were more than 200 g kg<SUP>-1</SUP>, however enzymatic conversions were increased dramatically comparing to untreated biomass. Therefore the correlation between lignin and enzymatic hydrolysis could not be explained just by lignin content, and other changes resulting from lignin removal affected enzymatic hydrolysis. Results on enzymatic conversion and sugar recovery suggested that the critical temperature improving enzymatic hydrolysis significantly was between 120 <SUP>o</SUP>C and 130 <SUP>o</SUP>C. Microscopic analysis using Field emission scanning electron microscopy (FE-SEM) showed that structural lignin changes happened through organosolv pretreatment. Lignins were isolated from lignin carbohydrate complex (LCC) at the initial stage and then migrated to the surface of biomass. The isolated and migrated lignins were finally redistributed onto surface. These structural changes formed droplets on surface and increased pore volume in pretreated biomass. The increase in pore volume also increased available surface area and enzyme adsorption at initial stage, and thus enzymatic conversion increased significantly through organosolv pretreatment. It was verified that the droplets were mainly composed of lignin and the lignin droplets inhibited enzymatic hydrolysis through adsorption with cellulase.
Effects of Implant Drill Wear, Irrigation, and Drill Materials on Heat Generation in Osteotomy Sites
Koo, Ki-Tae,Kim, Min-Ho,Kim, Hae-Young,Wikesjö,, Ulf M. E.,Yang, Jae-Ho,Yeo, In-Sung American Academy of Implant Dentistry 2015 The Journal of oral implantology Vol.41 No.2
<P>This study evaluated the effects of drill wear on bone temperature during osteotomy preparation with 3 types of drills and compared heat production between drills. The drills used in this study were titanium nitride-coated metal, tungsten carbide carbon-coated metal, and zirconia ceramic drills. An osteotomy 11 mm in depth was formed in bovine scapular bone following the manufacturer's recommended drill sequences. Drilling was performed without irrigation and repeated 20 times; temperature was measured every 5 times. Next, 200 rounds of drilling during irrigation were performed for each drill, with temperature change monitored until round 200. Analysis of variance statistics were used for analyses of the measured data. Drilling without irrigation showed significant thermal increase at all time points compared to drilling with irrigation (P < .001). No significant difference was found between drill materials. Under irrigation, the frequency of previous drilling had minimal effects on thermal change. The repeated-measures analysis of variance revealed major thermal change at the initial time point (P < .0001), and the multiple comparison tests revealed a significant difference in temperature between the initial drills that had been used 50 or fewer times and those that had been used more than 50 times, irrespective of the drill material. The results of this study indicate that the initial drill should be changed in osteotomy preparation with irrigation after they have been used 50 times. Irrigation may be a more critical factor for the control of temperature elevation than is the drill material.</P>