• 제목/요약/키워드: Spatial Clusters

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A Feature of Tidal Tails around Selective Globular Clusters in the Galactic Halo and Bulge

  • Chun, Sang-Hyun;Jung, Mi-Young;Han, Mi-Hwa;Chang, Cho-Rhong;Sohn, Young-Jong
    • 한국우주과학회:학술대회논문집(한국우주과학회보)
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    • 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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    • pp.38.1-38.1
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    • 2008
  • Tides caused by the Galactic gravitational field affect the current dynamical structure of globular clusters in the Galaxy. Indeed, the observed feature of tidal tails stretching beyond globular clusters' tidal radii provides a key information of interaction with the gravitational field of the Galaxy and kinematical orbit of the clusters, which can be an evidence of the merging scenario of the Galaxy formation and evolution. To find such a tidal feature, we have studied spatial density distribution of stars around five globular clusters in the Galactic halo and one cluster in the Galactic bulge, for which we have used wide-field deep photometric data of gri and JHK bands obtained from the MegaCam and WIRCam of the CFHT. Applying the statistical contrast filtering of field stars in the color-magnitude plane of detected stars around five halo clusters, we have found features of tidal tails for four clusters M53, M15, NGC 5053, and NGC 5466. The detected over-density tidal features are well aligned with the cluster's orbits and stretched into the direction of the Galactic center. Statistical analysis indicate that these tidal tails are believed to be cluster stars that have escaped due to the tidal effects to the clusters. A similar tidal feature to that of halo clusters is also detected for the bulge cluster NGC 6626, while the over-density feature seems to be extended into the Galactic plane rather than into the orbital direction and the Galactic center. Conclusively, our result adds further observational evidence of the merging scenario of the Galaxy formation and evolution.

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THE EVOLUTION OF THE GALACTIC GLOBULAR CLUSTERS.: I. METAL ABUNDANCE CALIBRATIONS

  • Lee, See-Woo;Park, Nam-Kyu
    • 천문학회지
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    • 제17권2호
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    • pp.69-103
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    • 1984
  • Five different calibrations of metal abundances of globular clusters are examined and these are compared with metallicity ranking parameters such as $(Sp)_c$, . Q39 and IR-indices. Except for the calibration $[Fe/H]_H$ by the high dispersion echelle analysis. the other calibration scales are correlated with the morphological parameters of red giant branch. In the $[Fe/H]_H$-scale. the clusters later than ${\sim}F8$ have nearly a constant metal abundance. $[Fe/H]_H{\simeq}-1.05$, regradless of morphological characteristics of horizontal branch and red giant branch. By the two fundamental calibration scales of $[Fe/H]_L$ (derived by the low dispersion analysis) and $[Fe/H]_{{\Delta}s}$ (derived by the spectral analysis of RR Lyrae stars). the globular clusters are divided into the halo clusters with [Fe/H]<-1.0 and the disk clusters confined within the galactocentric distance ${\tau}_G=10\;kpc$ and galactic plane distance |z|=3 kpc. In this case the abundance gradient is given by d[Fe/H]/$dr_G{\approx}-0.05\;kpc^{-1}$ and d[Fe/H]/$d|z|{\simeq}-0.08\;kpc^{-1}$ within ${\tau}_G=20\;kpc$ and |z|=10 kpc, respectively. According to these characteristics of the spatial distribution of globular clusters. the chemical evolution of the galactic globular clusters can be accounted for by the two-zone (disk-halo) slow collapse model when the $[Fe/H]_L$-or $[Fe/H]_{{\Delta}s}$-scale is applied. In the case of $[Fe/H]_H$-scale, the one-zone fast collapse model is preferred for the evolution of globular clusters.

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시공간 클러스터링 분석을 이용한 2010~2011 국내 발생 구제역 전파양상 (Temporospatial clustering analysis of foot-and-mouth disease transmission in South Korea, 2010~2011)

  • 배선학;신연경;김병한;박선일
    • 대한수의학회지
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    • 제53권1호
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    • pp.49-54
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    • 2013
  • To investigate the transmission pattern of geographical area and temporal trends of the 2010~2011 foot-and-mouth disease (FMD) outbreaks in Korea, and to explore temporal intervals at which spatial clustering of FMD cases space-time analysis based on georeferenced database of 3,575 burial sites, from 30 November 2010 to 23 February 2011, was performed. The cases represent approximately 98.1% of all infected farms (n = 3,644) during the same period. Descriptive maps of spatial patterns of the outbreaks were generated by ArcGIS. Spatial Scan Statistics, using SaTScan software, was applied to investigate geographical clusters of FMD cases across the country. Overall, spatial heterogeneity was identified, and the transmission pattern was different by province. Cattle have more clusters in number but smaller in size, as compared to the swine population. In addition, spatiotemporal analysis and the comparison of clustering patterns between the first 7 days and days 8 to 14 of the outbreak revealed that the strongest spatial clustering was identified at the 7-day interval, although clustering over longer intervals (8~14 days) was also observed. We further discussed the importance of time period elapsed between FMD-suspected notice and the date of confirmation, and emphasized the necessity of region-specific and species-specific control measures.

한국 친환경농업 생산공간의 변화와 여성노동력의 영향 (Changes in the Spatial Patterns of Organic Farming and the Women's Roles in the Agricultural Production in Korea)

  • 현기순;이금숙
    • 한국경제지리학회지
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    • 제16권4호
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    • pp.613-630
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    • 2013
  • 본 연구는 우리나라 농업공간의 변화에 영향을 미치는 여성노동력의 역할에 주목하고 2000년 이후 2010년까지 지난 10년 동안의 전국 친환경농업 생산공간의 분포 양상을 분석하였다. 입지계수와 LISA 분석을 적용하여 친환경농가의 공간적 특성을 파악하였는데, 먼저 입지계수를 통해 친환경농업 특화지역의 분포를 보면 지난 10년 동안 수도권 지역은 크게 감소한 반면 전남과 경북지역에서는 친환경농업 특화지역이 크게 확대되는 양상을 보인다. LISA 지표를 이용하여 친환경농업의 공간적 클러스터 패턴을 파악한 결과 2000년 서울 남쪽의 수도권 지역에만 형성되었던 친환경농업의 집적지가 2010년에는 전통적인 농업지역인 전남지역의 전역으로 크게 확대되는 양상을 보인다. 친환경농업에 작용하는 지리적 변수와의 관계성을 파악하기 위하여 다중회귀 분석을 실시한 결과 농가 경영주 성별이 여성인 농가수가 친환경 실천농가수에 정(+)의 상관관계를 보인다. 본 연구의 이러한 분석결과는 여성 경영주 농가와 친환경농업 공간의 연관성 측면에서 지속가능한 농업공간으로의 농업공간 재구조화에 여성인력이 중요한 역할을 하고 있음을 시사한다.

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Assessment and spatial variation of water quality using statistical techniques: Case study of Nakdong river, Korea

  • Kim, Shin
    • Membrane and Water Treatment
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    • 제13권5호
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    • pp.245-257
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    • 2022
  • Water quality characteristics and their spatial variations in the Nakdong River were statistically analyzed by multivariate techniques including correlation analysis, CA, and FA/PCA based on water quality parameters for 17 sites over 2017-2019, yielding PI values for primary factors. Site 10 indicated the highest parameter concentrations, and results of pearson's correlation analysis suggest that non-biodegradable organic matter had been distributed on the site. Five clusters were identified in order of descending pollution levels: I (Ib > Ia) > II (IIa > IIb) > III. Spatial variations started from sub-cluster Ib in which Daegu city and Geumho-river are joined. T-P, PO4-P, SS, COD, and TOC corresponded to VF 1 and 2, which were found to be principal components with strong influence on water quality. Sub-cluster Ib was strongly influenced by NO3-N and T-N compared to other clusters. According to the PIs, water quality pollution deteriorated due to non-biodegradable organic matter, nitrogen- and phosphorus-based nutrient salts in the middle and lower reaches, illustrating worsening water pollution due to inflows of anthropogenic sources on the Geumho-river, i.e., sewage and wastewater, discharged from Site 10, at which there is a concentration of urban, agricultural, and industrial areas.

한국의 산업클러스터에 관한 실증연구 (An Empirical Study on the Industrial Cluster in Korea)

  • 정병순;박래현
    • 한국경제지리학회지
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    • 제10권1호
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    • pp.19-43
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    • 2007
  • 본 연구는 산업클러스터를 식별하기 위한 방법론을 탐색하고, 이에 기초하여 한국의 산업클러스터를 식별하는데 목적이 있다. 이를 위해 2000년 I/O자료를 활용하여 상관계수행열표가 일차적으로 분석되고, 다시 이를 요인분석함으로써 최종적으로 산업클러스터를 도출하는 방법을 취하였다. 분석의 결과, 요인으로 도출된 37개 가운데 분류가 불분명한 5개 요인을 제외한 32개 요인이 최종 산업클러스터로 식별되었다. 이를 식별한 산업클러스터는 다시 산업코드 간 전환과정을 거쳐 표준산업분류체계에 의한 산업클러스터로 재구성함으로써 정책에의 적용 가능성을 향상시켰다. 이와 같은 연구결과는 대개 사례연구에 기초하거나 정성적 분석에 기초한 그간의 클러스터 연구와 비교하여 보다 체계적이고 객관적인 연구의 수행에 기여할 것으로 기대된다.

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Compact Binaries Ejected from Globular Clusters as GW Sources

  • 배영복;김정리;이형목
    • 천문학회보
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    • 제38권1호
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    • pp.57.2-57.2
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    • 2013
  • Based on N-body simulations, we find out that significant fraction of dynamically formed BH-BH (10 $M_{\odot}$ and NS-NS (1.4 $M_{\odot$ ecah) binaries are ejected from globular clusters. About 30 percent of compact stars are ejected in the form of binary. The merging time of ejected binary depends on the velocity dispersion of globular cluster. Some of ejected binaries have merging time-scales shorter than Hubble time and are expected to produce gravitational waves that can be detectable by the advanced ground-based interferometers. The merger rates of ejected BH-BH and NS-NS binaries per globular cluster are estimated to be 3.5 and 17 per Gyr, respectively. Assuming the spatial density of globular clusters as 8.4 $h^3$ clusters $Mpc^{-3}$ and extrapolating to the horizon distance of the advanced LIGO-Virgo network, we expect the detection rates solely attributed to BH-BH and NS-NS with cluster origin are to be 42 and 1.7 $yr^{-1}$, respectively. Besides, we find out that BH-NS binary ejection hardly occurs in globular clusters and dynamically formed compact binaries may possibly be the source of short GRBs whose locations are far from host galaxies.

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위치기반 소셜 미디어 데이터의 텍스트 마이닝 기반 공간적 클러스터링 분석 연구 (Spatial Clustering Analysis based on Text Mining of Location-Based Social Media Data)

  • 박우진;유기윤
    • 대한공간정보학회지
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    • 제23권2호
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    • pp.89-96
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    • 2015
  • 위치기반 소셜 미디어 데이터는 빅데이터, 위치기반서비스 등 다양한 분야에서 활용가능성이 매우 큰 데이터이다. 본 연구에서는 위치기반 소셜 미디어 데이터의 텍스트 정보를 분석하여 주요한 키워드들이 공간적으로 어떻게 분포하고 있는지를 파악할 수 있는 일련의 분석방법론을 적용해보았다. 이를 위해, 위치태그를 지닌 트윗 데이터를 서울시 강남지역과 그 주변지역에 대하여 2013년 8월 한달 간 수집하였으며, 이 데이터를 대상으로 하여 텍스트 마이닝을 통해 주요 키워드들을 도출하였다. 이러한 키워드들 중 음식, 엔터테인먼트, 업무 및 공부의 세 카테고리에 해당하는 키워드들만 추출, 분류하였으며 각 카테고리에 해당하는 트윗 데이터들에 대해서 공간적 클러스터링을 실시하였다. 도출된 각 카테고리별 클러스터들을 실제 그 지역의 건물 또는 벤치마크 POI들과 비교한 결과, 음식 카테고리 클러스터는 대규모 상업지역들과 일치도가 높았고 엔터테인먼트 카테고리의 클러스터는 공연장, 극장, 잠실운동장 등과 일치하였다. 업무 및 공부 카테고리 클러스터들은 학원 밀집지역 및 사무용 빌딩 밀집지역과 높은 일치도를 나타내었다.

수질 및 유량자료의 기초통계량 분석에 따른 공간분포 파악을 위한 SOM의 적용 (Application of SOM for the Detection of Spatial Distribution considering the Analysis of Basic Statistics for Water Quality and Runoff Data)

  • 진영훈;김용구;노경범;박성천
    • 한국물환경학회지
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    • 제25권5호
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    • pp.735-741
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    • 2009
  • In order to support the basic information for planning and performing the environment management such as Total Maximum Daily Loads (TMDLs), it is highly recommended to understand the spatial distribution of water quality and runoff data in the unit watersheds. Therefore, in the present study, we applied Self-Organizing Map (SOM) to detect the characteristics of spatial distribution of Biological Oxygen Demand (BOD) concentration and runoff data which have been measured in the Yeongsan, Seomjin, and Tamjin River basins. For the purpose, the input dataset for SOM was constructed with the mean, standard deviation, skewness, and kurtosis values of the respective data measured from the stations of 22-subbasins in the rivers. The results showed that the $4{\times}4$ array structure of SOM was selected by the trial and error method and the best performance was revealed when it classified the stations into three clusters according to the basic statistics. The cluster-1 and 2 were classified primarily by the skewness and kurtosis of runoff data and the cluster-3 including the basic statistics of YB_B, YB_C, and YB_D stations was clearly decomposed by the mean value of BOD concentration showing the worst condition of water quality among the three clusters. Consequently, the methodology based on the SOM proposed in the present study can be considered that it is highly applicable to detect the spatial distribution of BOD concentration and runoff data and it can be used effectively for the further utilization using different water quality items as a data analysis tool.

지역 간 상호연계에 기반 한 농촌과 도시 간 생활권의 차이 - 부산.울산 광역도시권을 중심으로 - (Disparity between Rural and Urban Living Area Based on Regional Interaction - Focused on Busan-Ulsan mega city -)

  • 김현종;강동우;조덕호;이성우
    • 농촌계획
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    • 제16권4호
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    • pp.61-75
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    • 2010
  • Daily living area can be delimited differently depending on what area is to be focused. Based on regional interaction, the present study empirically analyzed the difference between living areas focusing on rural area and ones relying on urban area. We established two types of living areas in Busan-Ulsan mega city with different focus areas (rural versus urban), using travel OD data (2006). According to the result, the fonn of spatial clusters in urban living area differed from that of spatial clusters in rural area; the boundaries of living area were not fit to those of administrative areas in both types; and living areas in both types tended to extend over more than two administrative areas. The results cast some implications concerning spatial planning and policy for living area delimitation. First, since the spatial structure and interconnection of urban area differs to those of rural area, it is required to delimit living areas discriminatively depending on the objectives of the spatial plan. Additionally, the living area should be established more specifically and systematically by further subdividing the form of spaces depending on the objectives and types of the plan. Second, the administrative areas should be consolidated now that the difference of boundaries of administrative and living areas lead to inconvenience of residents, increased administration costs and scale diseconomy. Lastly, the living areas should be delimited by the metropolitan or mega city planning and thus be reflected to its offsprings.