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전종갑,예상욱,권민호,정용승 한국교원대학교 환경과학연구소 2001 환경연구논문집 Vol.- No.6
Yellow-sand phenomena which observed in the springtime in South Korea for the period of 1967-1996 have been investigated. The result shows that the average number of yellow-sand days and events per spring is 8.4 and 3.4, respectively, and the average duration of yellow-sand phenomena is 18.5 hours. Also, yellow-sand data at ten big cities are statistically analyzed in terms of frequency and duration according to the source region of yellow sands far the period of 1980~1994. Yellow sands observed in South Korea originated from the Takla-Makan Desert, the Gobi Desert and/or the Loess Plateau. The mean number of yellow-sand days in the springtime in those origins is 52.5, 29.1, and 7.5, respectively. In the Gobi Desert and the Loess Plateau yellow sands occurred most frequently in April. The cases of long-lasting yellow sands are analyzed in terms of the background synoptic patterns. The case of yellow sands reaching to the Korean Peninsula is compared with the case of these not reaching, by classifying the flow patterns in the upper layer using a Kirchhofer method. The results show that the important factors of the circulation influencing on the yellow-sand transport to the Korean Peninsula are the location of trough on the 500 hPa or the 700 hPa level and the flow direction on the 850 hPa level.
한반도에서 관측된 1998년 4월 황사의 특성 및 장거리 수송패턴 분석
전종갑,예상욱,곽용문,정용승 한국교원대학교 환경과학연구소 2001 환경연구논문집 Vol.- No.6
A yellow-sand phenomenon which was observed in South Korea for the period of 14 to 22 April 1998 has been investigated. This long-lasted case has the maximum number of both yellow-sand days per event and duration hours for recent 30 years in South Korea. The yellow-sand particles which were transported across the North Pacific increased the concentration of aerosol in the west region of North America. Meteorological variables in the source region of yellow sand, yellow-sand records in ten big cities in South Korea, and the MPL (Micro Pulse Lidar) data at Seoul for this period hale been also analysed. The results show that the yellow sands observed in South Korea originated mainly from Loess Plateau and Gobi Desert, where the yellow sands occurred for the period of 12 to 22 April 1998. The strong surface wind more than 10m/s was observed for this period at a weather station in which is located in Loess Plateau. The longest record of that duration of yellow sand is 194.6 hours at Seoul. Especially, the MPL data show that the particles of yellow sand were transported in the whole layer up to 5 km height vertically. Through the zonal wind analysis of NCEP reanalysis data, it has been found that the zonal wind speed over the midlatitude North Pacific was much stronger than that in the normal state. In addition, the geopotential field analysis shows that the direction of flow had the zonality and there was the strong north-south geopotential gradient which is related to the zonal wind intensity in this region. The EOF (Empirical Orthogonal Function) analysis of 850 hPa geopotential field implies that the second mode, which is related to the intensity of subtropical high, has a close connection to the atmospheric circulation pattern which can transport the yellow sands across the North Pacific.
Selective Synthesis of 3,4-Dihydrocoumarins and Chalcones from Substituted Aryl Cinnamic Esters
전종갑,Deok-Mo Yang,Jong-Gab Jun 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.1
Coumarins are ubiquitous in plant kingdom and have been used as antitumor, antifungals, anticoagulants, insecticides. Chalcones are also widespread in plant kingdom and have been known to possess diverse biological activities;antibacterial, antifungal, antitumor and anti-inflammatory, etc. As they are considered as important natural products,numerous synthetic approaches have been reported up to the present. We devise a new selective method of preparing dihydrocoumarins and chalcones from aryl cinnamates by the selection of reagents. Dihydrocoumarin derivatives were prepared selectively by using intramolecular cyclization catalyzed by p-toluene sulfonic acid. Also, chalcones were prepared by Fries-rearrangement catalyzed by TiCl4. This method can be used for preparing various coumarin & chalcone compounds.