• 제목/요약/키워드: Temporal and Spatial Distribution

검색결과 644건 처리시간 0.032초

Spatial-temporal distributions of the newly described mixotrophic dinoflagellate Gymnodinium smaydae in Korean coastal waters

  • Lee, Sung Yeon;Jeong, Hae Jin;Ok, Jin Hee;Kang, Hee Chang;You, Ji Hyun
    • ALGAE
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    • 제35권3호
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    • pp.225-236
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    • 2020
  • Gymnodinium smaydae is a newly described mixotrophic dinoflagellate that feeds on only Heterocapsa spp. and Scrippsiella acuminata among 19 tested algal prey. It is one of the fastest growing dinoflagellates when feeding, but does not grow well without prey. To investigate its spatial-temporal distributions in Korean waters, we quantified its abundance in water samples that were seasonally collected from 28 stations along the Korean Peninsula from April 2015 to October 2018, using quantitative real-time polymerase chain reactions. This dinoflagellate had a wide distribution, as reflected by the detection of G. smaydae cells at 23 of the sampling stations. However, this distribution had a strong seasonality; it was detected at 21 stations in the summer and only one station in winter. The abundance of G. smaydae was significantly and positively correlated with chlorophyll a concentration as well as with water temperature. However, there were no significant correlations between the abundance of G. smaydae and salinity, concentrations of nutrients, or dissolved oxygen concentration. During the study period, G. smaydae was present when water temperatures were 7.6-28.0℃, salinities were 9.6-34.1, concentrations of NO3 were not detectable-106.0 μM, and concentrations of PO4 were not detectable-3.4 μM. The highest abundance of G. smaydae was 18.5 cells mL-1 in the coastal waters of Jinhae in July 2017 when the chlorophyll a concentration was 127 mg m-3 and water temperature was 23.8℃. Therefore, the spatial-temporal distribution of G. smaydae in Korean coastal waters may be affected by chlorophyll a concentration and water temperature.

수질오염총량관리 단위유역의 유량변화 특성분석 - 금강수계를 대상으로 - (Characterization on the Variation of Streamflow at the Unit Watershed for the Management of Total Maximum Daily Loads - in Guem River Basin -)

  • 박준대;오승영;최옥연
    • 한국물환경학회지
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    • 제27권6호
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    • pp.914-925
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    • 2011
  • The variation of streamflow is regarded as one of the most influential factors on the fluctuation of water quality in the stream. The characteristics of the variation should be taken into account in the plans for the management of Total Maximum Daily Loads (TMDLs). This study analysed and characterized spatial distribution and temporal variation of streamflow at each unit watershed in Guem-river basin. For the analysis of the distribution of streamflow, the type and the extent of the distribution were investigated for the unit watershed. For the analysis of the variation, short and long term changes of streamflow were examined. The result showed that most of the distributions were not log-normalized and the extent of variation tends to be greater at the unit watershed placed on the tributaries in the basin. A kind of margin could be granted to the unit watershed involving high variations so as to establish the water quality goal and load allotment more reasonably and effectively in view of whole waterbody.

Analysis of Temporal and Spatial Variation of Precipitable Water Vapor According to Path of Typhoon EWINIAR using GPS Permanent Stations

  • Won, Jihye;Kim, Dusik
    • Journal of Positioning, Navigation, and Timing
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    • 제4권2호
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    • pp.87-95
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    • 2015
  • In this study, the temporal and spatial variation in precipitable water vapor (PWV) was analyzed for typhoon Ewiniar which had made landfall in the Korean peninsula in 2006. To make a contour map of PWV, zenith total delay (ZTD) was calculated using about 60 GPS permanent stations in Korea, and the pressure and temperature data of nearby AWS stations were interpolated and applied to the equation for calculating the PWV. While Typhoon Ewiniar was migrating north from the southern coast to the eastern coast of Korea, the PWV migrated showing a spatial distribution similar to that of rainfall. Also, the fluctuating pattern of the normalized PWV was analyzed, and the moving speed of the PWV was estimated using the delay time of the increase/decrease pattern in the eight-test stations. The result indicated that the moving speed of the PWV was about 35 km/h, which was similar to the average moving speed of the typhoon (38.9 km/h).

시공간 종속성을 고려한 빈집발생 요인 추정에 관한 연구 (Study on Factors of Vacant Houses's Occurrence using Spatio-Temporal Model)

  • 김유현;김동현
    • 한국지리정보학회지
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    • 제26권2호
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    • pp.20-41
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    • 2023
  • 최근 저출산·고령화에 따른 도시축소 현상과 지방도시의 쇠퇴는 빈집이라는 새로운 도시문제를 낳고 있다. 본 연구는 전국 시·군·구를 대상으로 2015년부터 2019년까지 수집한 공간 패널 데이터를 이용하여 빈집 분포를 살펴보고 시공간적 종속성을 고려한 공간패널모형을 이용하여 빈집발생의 요인을 추정하는 것이 목적이다. 분석 결과 빈집은 시공간적으로 종속성이 있었으며, OLS 모형에 비해 시공간적 종속성을 고려하여 빈집 발생 요인을 추정하는 것이 타당함을 확인하였다. 동적공간패널모형을 이용하여 분석한 결과 빈집발생의 가장 큰 영향요인은 주택관련요인인 것으로 나타났다. 이 결과는 빈집 발생의 관리를 위해서는 인구이동, 양호하지 못한 인프라 등 뿐만 아니라 주택 공급량에 대한 정책적 고려가 필요함을 시사한다.

4-D PTV

  • Doh Deog Hee;OKAMOTO Koji
    • 한국가시화정보학회:학술대회논문집
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    • 한국가시화정보학회 2004년도 Proceedings of 2004 Korea-Japan Joint Seminar on Particle Image Velocimetry
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    • pp.33-40
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    • 2004
  • A 4D-PTV system was constructed. The measurement system consists of three high-speed high-definition cameras(1k x 1k, 2000fps), Nd-Yag laser(2000Hz) and a host computer. The GA-3D-PTV algorithm was used for completing the measurement system. The 4D-PTV is capable of probing the spatial distribution of velocity vectors of the flow field overcoming the temporal resolution of the characteristic turbulence length scales of the measured flow fields. A horizontal impinged jet flow (H/D=7) was measured. The Reynolds number is about 33,000. Spatial temporal evolution of the jet flow was examined and physical properties such as spatial distributions of vorticity and turbulent kinetic energy were obtained with the constructed.

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