• Journal of Astronomy and Space Sciences
• /
• v.24 no.2
• /
• pp.125-134
• /
• 2007

In this paper, we analyze the orbital variation of the Korea Multi-Purpose SATellite-1(KOMPSAT-1) in a strong space environment due to satellite drag by solar and geomagnetic activities. The satellite drag usually occurs slowly, but becomes serious satellite drag when the space environment suddenly changes via strong solar activity like a big flare eruption or coronal mass ejections(CMEs). Especially, KOMPSAT-1 as a low earth orbit satellite has a distinct increase of the drag acceleration by the variations of atmospheric friction. We consider factors of solar activity to have serious effects on the satellite drag from two points of view. One is an effect of high energy radiation when the flare occurs in the Sun. This radiation heats and expands the upper atmosphere of the Earth as the number of neutral particles is suddenly increased. The other is an effect of Joule and precipitating particle heating caused by current of plasma and precipitation of particles during geomagnetic storms by CMEs. It also affects the density of neutral particles by heating the upper atmo-sphere. We investigate the satellite drag acceleration associated with the two factors for five events selected based on solar and geomagnetic data from 2001 to 2002. The major results can be summarized as follows. First, the drag acceleration started to increase with solar EUV radiation with the best cross-correlation (r = 0.92) for 1 day delayed F10.7. Second, the drag acceleration and Dst index have similar patterns when the geomagnetic storm is dominant and the drag acceleration abruptly increases during the strong geomagnetic storm. Third, the background variation of the drag accelerations is governed by the solar radiation, while their short term (less than a day) variations is governed by geomagnetic storms.

• KSBB Journal
• /
• v.18 no.3
• /
• pp.211-216
• /
• 2003

The removal yield of dissolved organic matter in drinking water by biological activated carbon (BAC) process was investigated. The tested processes wer raw water-AC process (BAC1), raw water-ozonation-BAC process (BAC2), and raw water-ozonation-coagulation/sedimentation-BAC process (BAC3). The amounts of organic matter was measured as dissolved organic carbon (DOC), ulta-violet radiation at 254 nm wavelength ($UV_{254}$), total nitrogen (T-N), ammonia nitrogen (NH_3$-N), and total phosphate (T-P). As a results, 30.7% DOC was removed by BAC2 process, which showed higher removal efficiency than BAC1 or BAC3 processes. The removal yield of $UV_{254}$ in BAC1, BAC2, and BAC3 processes were observed as 45.3%, 44.6%, 58.4%, respectively. And the removal yield of ammonia nitrogen were 66%, 81%, 29% in each BAC processes. The optimal empty bed contact time (EBCT) of BAC processes was estimated as 10 minute. This study has shown that BAC process combined with ozone treatment was efficient for removing dissolved organic matter in water.

• Journal of Mushroom
• /
• v.11 no.2
• /
• pp.99-106
• /
• 2013

This study was initiated to investigate the skin whitening activities of methanol extracts from fruiting bodies of I. obliquus. The total polyphenols and flavonoids contents of I. obliquus methanol extracts were 31.85 mg/g and 28.33 mg/g, respectively. The methanol extract of the mushroom treated on B16/F10 melanoma and NIH3T3 cell lines did not show cytotoxic activity. 2,2-diphenyl-1-picrylhydrazyl(DPPH) free radical scavenging activity and chelating activity on ferrous ions of I. obliquus methanol extract were lower than those of positive control, tocopherol and BHT. The tyrosinase and L-DOPA inhibitory activities of the extract were lower than those of positive control, kojic acid and ascorbic acid. The tyrosinase and melanin synthesis inhibitory activities of the melanoma cells treated with the extract were comparable with positive control, arbutin. The experimental results suggested that methanol extract of I. obliquus contained inhibitory activities of tyrosinase and melanin synthesis in the B16/F10 melanoma cells by dose dependent manner. High ultra-violet absorption spectra in the range of 280-350 nm showed that I. obliquus extract could protect skin from UV radiation damage. Therefore, fruiting bodies of I. obliquus can be used for developing skin whitening, anti-UV and skin care agents.