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조형욱,박병훈,김용민,최철희,최성희,김기홍,천권수 한국방사선학회 2011 한국방사선학회 논문지 Vol.5 No.5
경 X선 형광분석 기법에 사용되는 X선 튜브는 X선의 휘도가 낮아 분석의 정밀도가 떨어지고 분석 시간 또한 오래 걸린다. 모세관 집광소자를 이용하면 X선 휘도의 이득(gain)을 최소 10 이상 얻을 수가 있다. 모세관 광학소자는 8.4keV의 텅스텐 특성방사선을 효율적으로 집광할 수 있도록 설계되었다. 파이렉스 유리로 된 모세관 모재를 풀러 (puller)를 이용하여 45 g의 추에 650˚의 온도를 가하여 모세관 광학소자를 제작하였다. 모세관 광학소자의 제작은 총 460분이 소요되었으며 제작된 모세관 광학소자의 길이는 87 mm, X선 입사부의 직경은 300 ㎛, 출구부의 직경은 192 ㎛로 제작되었다. 제작된 모세관 광학소자를 경 X선 형광분석에 적용하면 황(S)과 같은 경원소 검출의 정밀도를 높일 수 있을 것이다. An X-ray tube used an X-ray fluorescence analysis system has a low X-ray photon intensity which results in reducing measurement accuracy and increasing exposure time. These shortages can be overcame by using a monocapillary optics. A monocapillary optics was optimally designed for focusing the characteristic X-ray of tungsten (8.4 keV). The monocapillary optics can achieve a gain of 10 at the least. The monocapillary optics was fabricated by using puller and pyrex glass, raw material. In fabrication, a weigh of 45g and a temperature of 650˚ was loaded. The total fabrication time was 460 minutes. The fabricated capillary had 87 mm in length and maximum diameter of 300 ㎛ and minimum diameter of 192 ㎛. When the fabricated monocapillary optics is applied to an X-ray fluorescence analysis system, the detection accuracy for soft elements, for example sulfur (S), will be improved.
코로나19 전후 대구광역시 도시공간의 유동인구 분포 변화 : 핫스팟 분석을 중심으로
조형욱,김다솜,이삼수 대한국토·도시계획학회 2022 國土計劃 Vol.57 No.2
The coronavirus disease (COVID-19) pandemic has brought about many socioeconomic changes in Korea. Due to the extremely high contagiousness of COVID-19, structural and physical shifts in urban spaces have been examined, while focusing on urban density, resident population, and de facto population. This study examines both spatial and temporal patterns of the de facto population, or floating population in the Daegu metropolitan area. Monthly data from January 2019 to October 2020 are used to compare the impacts of the COVID-19 pandemic. In addition, the hotspot analysis is performed by employing the rate of change of the floating population. This study shows that there is a temporal difference between the reduction and the recovery periods of the floating population. The difference significantly depends on the type of land use in urbanized areas; it also depends on whether the population in a specific place has substantially declined. In particular, the floating population was restored to the green areas immediately after the pandemic, creating many hotspots of floating populations in the same places. The results suggest that the impact of the COVID-19 pandemic on changes in urban spaces are not homogeneous according to the type of land use. The role of green spaces in coping with a pandemic such as COVID-19 is also noteworthy.