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Photoionization Cross Section of Hydrogenic Impurities in SphericalQuantum Dots: In nite Well Model
Heon Ham,Cheol Jin Lee 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.III
We have used a variational wave function for hydrogenic impurities in spherical quantum dots to calculate the dependence of the photoionization cross section of such impurities on the photon energy. The calculation has been performed using the infinite confining well model. The results are presented for various dot radii and for different locations of the impurity in the dot. We find that for hydrogenic impurities at the center of a spherical quantum dot, the transition takes place between the impurity level associated with the ground subband and the free particle state in the second subband, and the cross section is independent of the polarization of the photons. For off-center impurities, the transition takes place between the impurity level associated with the ground subband and the free particle state in the ground subband when the photons are polarized along the direction connecting the impurity with the center of the dot while for photons polarized perpendicular to the direction, we find that the transitions take place between the impurity level associated with the ground subband and the free particle state in the second subband.
유소년 축구팀의 체력 및 기본기술 수준과 경기력의 관계
함상헌 ( Sang Heon Ham ) 한국스포츠코칭학회 2015 한국스포츠코칭학회지 Vol.1 No.1
이 연구는 유소년 축구선수들의 체력과 기본기술 수준 및 경기력의 관계를 구명하는데 연구의 목적이 있었다. 이와 같은 연구목적을 달성하기 위해 초등부 전국축구리그 서울특별시 권역리그 참가하고 있는 2개의 팀을 선정하였다. 선정한 팀을 대상으로 주축선수 13명의 체력과 축구 기본기술을 리그 시작 전에 측정 하였으며 경기력은 리그가 끝난 후 평가 하였다. 자료 분석 방법은 SPSS 15.0 Version 통계 프로그램을 이용하여 기술 통계분석과 독립표본 t-test를 실시하였다. 이러한 절차를 통하여 유소년 축구선수들의 체력과 기본기술 수준이 경기력과 상관관계를 분석한 결과 결론은 다음과 같다. 첫째, 유소년 S팀의 측정한 평균치는 505 Agility Test 4.62초, 트래핑 2.38개, 드리블 11.49초, 슈팅 1.08개, 헤딩 .92개로 측정됐으며 유소년 I팀은 505 Agility Test 4.81초, 트래핑 1.62개, 드리블 13.91초, 슈팅 .92개, 헤딩 .62개로 측정됐다. 둘째, 유소년 축구팀의 체력 및 기본기술에 대한 차이는 부분적으로 505 Agility Test(p=.042), 트래핑(p=.017), 드리블(p=.001)에서 통계적인 유의한 차이가 있다. 셋째, 유소년 축구팀의 체력 및 기본기술은 경기력과 상관관계가 있다. The purpose of this study was to specify relationships among youth soccer players’ physical strength, level of basic skills, and athletic performance. In order to achieve this study purpose, two teams participating in the Seoul Metropolitan City league of the national elementary school soccer league in were selected. Targeting the selected teams, main 13 players’ physical strength and basic skills were measured before begging of the league, and their athletic performance was evaluated after the league was over. For a data analysis, a descriptive statistical analysis and independent t-test were conducted by using the SPSS PC+ 15.0 Version statistical program. The study results of analyzing relationships among youth soccer players’ physical strength, level of basic skills, and athletic performance through these procedures are as below. First, the averages of youth S team were 505 agility test 4.62 seconds, trapping 2.38, dribble 11.49 seconds, shooting 1.08, and heading .92, and those of youth I team were 505 agility test 4.81 seconds, trapping 1.62, dribble 13.91 seconds, shooting .92, and heading .62. Second, youth soccer teams’ physical strength and basic skills had partially and statistically significant differences on 505 agility test (p=.042), trapping (p=.017), and dribble (p=.001). Third, youth soccer teams’ physical strength and basic skills had correlations with athletic performance.
Ham, Hyeonmi,Yoon, Sung Won,Kim, In-Hwan,Kwak, Jieun,Lee, Jeom-Sig,Jeong, Heon-sang,Lee, Junsoo Elsevier 2015 FOOD SCIENCE AND TECHNOLOGY -ZURICH- Vol.61 No.2
<P><B>Abstract</B></P> <P>Rice bran is a byproduct of the rice milling process. It contains high levels of bioactive phytochemicals such as phytosterols, tocopherols, tocotrienols, γ-oryzanol, triterpene alcohol, and other minor compounds, which have antioxidant and health-promoting properties. The objective of this study was to evaluate the?protective effect of unsaponifiable matter (USM) from rice bran against oxidative damages induced by <I>tert</I>-butyl hydroperoxide (TBHP) in HepG2 cells. Levels of cellular reactive oxygen species (ROS), cellular lipid peroxidation, reduced glutathione (GSH), and antioxidant enzyme activity were evaluated as biomarkers of the cellular oxidative status. HepG2 cells were pretreated with various concentrations of USM (0–100?μg/mL) for 12?h prior to TBHP exposure. Pretreatment of HepG2 cells with USM prevented the cell damage induced by TBHP in a dose-dependent manner. Cellular generation of ROS, formation of malondialdehyde (MDA), and depletion of GSH induced by TBHP were prevented by pretreatment with USM. In addition, treatment with TBHP increased the activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase. However, pretreatment with USM significantly reduced the activities of these enzymes. These results indicate that treatment of HepG2 cells with USM confers significant protection against oxidative damage by modulating ROS production, GSH levels, and antioxidant enzyme activity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Unsaponifiable matter (USM) was prepared from rice bran. </LI> <LI> USM prevented the cell damage in a dose-dependent manner. </LI> <LI> Oxidative changes induced by oxidative stress were prevented by USM. </LI> <LI> USM significantly modulated antioxidant enzyme activities of HepG2 cells. </LI> </UL> </P>