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Development of the SNU Coelostat: Conceptual Design
강주형,채종철,곽한나,양희수 한국천문학회 2018 Journal of The Korean Astronomical Society Vol.51 No.6
A coelostat is often used for solar observations, because it corrects the image rotation automatically by guiding sunlight into a fixed telescope with two plane mirrors. For the purposes of education and spectroscopic observation, the solar group at Seoul National University (SNU) plans to develop the SNU coelostat (SNUC) and install it in the SNU Astronomical Observatory (SAO). Requirements of the SNUC are $<1''$ positioning accuracy with 30~cm beam size on the entrance pupil in the compact dome. To allow for installation in the small dome, we design a compact slope type coelostat with a 45 cm primary plane mirror and a 39 cm secondary plane mirror. The motion of the SNUC is minimized by fixing the position of the slope frame. Numerical simulations of the available observational time of the designed coelostat shows that the sun can be observed ay all times from June to early August and at least three hours in other months. Since the high accuracy driving motors installed in the SNUC can be affected by external environment factors such as humidity and temperature variations, we design a prototype to test the significance of these effects. The prototype consists of a 20 cm primary plane mirror, a 1 m slope rail, a direct drive motor, a ballscrew, a linear motion guide, an AC servo motor, a reduction gear and a linear encoder. We plan to control and test the accuracy of the prototype with varying atmospheric conditions in early 2019. After testing the prototype, the SNUC will be manufactured and installed in SAO by 2020.
강주형,원지현,황재관,강원구 한국식품과학회 2022 Food Science and Biotechnology Vol.31 No.10
Although xanthorrhizol, a sesquiterpenoid oil obtained from the rhizome of Curcuma xanthorrhiza Roxb., known as Java turmeric, has many pharmacological effects, its pharmacokinetics remain unclear. Therefore, we investigated the pharmacokinetics of xanthorrhizol in mice and rats. Xanthorrhizol was administered intravenously and orally to mice, while xanthorrhizol and a Java turmeric supercritical extract were administered orally to rats. The terminal half-life (t1/2), clearance, and absolute bioavailability (BA) of xanthorrhizol in mice were almost 8 h, 6.5 L/h/kg, and 10.2%, respectively. In comparison, the clearance of xanthorrhizol was 3-fold higher in rats than mice. The absolute BAs of xanthorrhizol in rats were 12.9% and 13.4% after oral administration of xanthorrhizol and a supercritical extract, respectively. Our results regarding the pharmacokinetics of xanthorrhizol could guide the conversion of intravenous and oral doses, and help identify the optimal maintenance doses of xanthorrhizol and the extract for desirable pharmacodynamic effects.
강주형,김보혜,이선이,김영진,이준원,박영민,안순철,Kang Ju-Hyung,Kim Bo-Hye,Lee Sun-Yi,Kim Yeong-Jin,Lee Ju-Won,Park Young Min,Ahn Soon-Cheol 한국생명과학회 2005 생명과학회지 Vol.15 No.6
Although valuable microbes have been isolated from the soil for the various productions of useful components, the microbes which can be cultivated in the laboratory are only $0.1-1\%$ of all microbes. To solve this problem, the study has recently been tried for making the valuable components from the environment by directly separating unculturable micrbial DNA in the soil. But it is known that humic acid originated from the soil interrupts various restriction enzymes and molecular biological process. Thus, in order to prevent these problems, this study modified the method separated soil DNA with phenol, CTAB and PEG. In order to compare the degree of purity for each DNA and the molecular biological application process, $A_{260}/A_{280}$ ratio, restriction enzymes, and PCR were performed. In case of DNA by the modified method, total yield of DNA was lower but $A_{260}/A_{280}$ ratio was higher than the previously reported methods. It was confirmed that the degree of purity is improved by the modified method. But it was not cut off by all kinds of tested restriction enzymes because of the operation of a very small amount of interrupting substances. When PCR was operated with each diluted DNA in different concentrations and GAPDH primer, the DNA by the modified method could be processed for PCR in the concentration of 100 times higher than by the previously reported separation method. Therefore, this experiment can find out the possibility of utilization for the unknown substances by effectively removing the harmful materials including humic acid and help establishing metagenomic DNA library from the soil DNA having the high degree of purity.