• Ocean and Polar Research
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• 제44권2호
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• pp.179-190
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• 2022

Data missing in optical satellite images caused by natural variations have been a crucial barrier in observing the status of marine surfaces. Although there have been many attempts to fill the gaps of non-observation, there is little research to analyze the ratio of missing grids to overall sea grids and their seasonal patterns. This report introduces the method of quantifying the distribution of missing points and then shows how the missing points have spatial correlation and seasonal trends. Both temporal and spatial integration methods are compared to assess the effectiveness of reducing missing data. The temporal integration shows more outstanding performance than the spatial integration. Moran's I and K-function with statistical hypothesis testing show that missing grids are clustered and there is a non-random distribution from daily integration. The result of the seasonality test for Moran's I through a periodogram shows dependency on full-year, half-year, and quarter-year periods respectively. These analysis results can be used to deduce appropriate integration periods with permissible estimation errors.

• Spatial Information Research
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• 제8권2호
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• pp.233-241
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• 2000

The objective of this study were to develop landscape scale ecosystem assessment model, and apply the model for the assessment of the state and change of ecosystem of the study area, Yongin, Korea. Since natural ecosystem of the site has been deteriorated significantly during recent extensive residential development, it is essential to correctly assess ecosystem of the study site. Traditional ecosystem assessment mainly utilizing intensive field survey requires high cost, but the outcome rarely represents spatial pattern of the regional ecosystems. Ecosystem assesment of landscape scale based on landscape ecology can resolve most of the shortfalls of the traditional approach. The research method can be summarized as follows. First, extensive literature review on such topics as spatial pattern of ecosystem, ecosystem assessment of landscape scale, ecological analysis was carried out. Second, a model for the ecosystem assessment of landscape scale emphasizing spatial pattern of ecosystem was developed. This model evaluates three indicators; ecological integrity and biological diversity, watershed integrity, and landscape resilience of 11 watersheds in the study area. Finally, ecological assessment utilizing two sets of indicators, enhancement of and disturbance of ecosystem stability, was carried out. This assessment method is based on Environmental Monitoring and Assessment Program´s Landscape component(EMAP-L) of EPA(1994). The results of this study are as follows. First, the ecosystem assessment of landscape scale of the study area of Yongin, Korea, showed that escosystems of Tanchun01 and Chungmichun01 watersheds had the worst state in the study site in 1991. On the other hand, the ecosystems of Jinwechun01, Kyunganchun02, and Bokhachun01 watersheds had the most stable ecosystem in 1991. Second, ecosystems of Tanchun01, Shingal reservoir, and Kyunganchun01 watersheds were evaluated to be the worst state in the study site in 1996. And, ecosystems of Jinwechun01 and Gosam reservoir watersheds had the most stable ecosystem. Third, ecosystem of Tanchun01 watershed which incudes Suji residential development project site changed the most drastically between 1991 and 1996. The ecosystem of the watershed the most drastically deteriorated due to it´s proximity to Seoul and Bundang new town.

• 대한의용생체공학회:의공학회지
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• 제27권1호
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• pp.22-29
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• 2006

This paper proposes an efficient array beamforming method using spatial matched filtering for ultrasound imaging. In the proposed method, ultrasound waves are transmitted from an array subaperture with fixed transmit focus as in conventional array imaging. At receive, radio frequency (RF) echo signals from each receive channel are passed through a spatial matched filter that is constructed based on the system transmit-receive spatial impulse response. The filtered echo signals are then summed. The filter remaps and spatially registers the acoustic energy from each element so that the pulse-echo impulse response of the summed output is focused with acceptably low side lobes. Analytical beam pattern analysis and simulation results using a linear array show that the proposed spatial filtering method can provide more improved spatial resolution and contrast-to-noise ratio (CNR) compared with conventional dynamic receive focusing (DRF) method by implementing two-way dynamically focused beam pattern throughout the field.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1242-1242
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• 2003

• 지역연구
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• 제34권2호
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• pp.35-47
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• 2018

본 연구는 개별 건축물 데이터를 활용하여 대구광역시의 빈집 발생의 공간패턴과 발생요인을 분석하였다. 핫스팟 분석을 통해 빈집 발생의 공간패턴을 분석한 결과, 대구광역시 도심을 중심으로 도넛형태의 빈집밀집 구역이 존재하고 있음을 확인하였다. 로지스틱 회귀분석을 통한 빈집의 발생요인 분석은 개별 건축물의 물리적 특성과 지역의 사회 경제적 특성을 함께 고려하여 분석하였다. 빈집의 발생요인 분석 결과, 개별 건축물의 물리적 특성 중에는 건물면적, 층수, 노후도가 빈집 발생에 유의미한 영향을 주는 것으로 나타났다. 빈집은 건물면적이 작을수록, 층수는 낮을수록, 건축연식이 오래될수록 발생확률이 높았다. 지역특성 측면에서는 정비구역 내 입지 유무, 최근 5년간 인구성장률, 노인인구 비율과 더불어 인접빈집수가 중요한 변수로 파악되었다. 빈집의 발생확률은 정비구역 내에 위치할수록, 지역의 인구성장률이 낮을수록, 노인인구의 비율이 낮을수록 증가하는 것으로 나타났으며, 특히 인접빈집수가 많을수록 빈집 발생 확률도 높게 나타나 빈집 발생에 공간적 연관성이 존재함을 실증적으로 보여준다.

• Ocean Science Journal
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• 제43권2호
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• pp.67-79
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• 2008

We investigated the relationship between mesoscale spatial distribution of environmental parameters (temperature, salinity, and sigma-t), chlorophyll-a concentration and mesozooplankton in the Yellow Sea during May 1996, 1997, and 1998, with special reference to Yellow Sea Bottom Cold Water (YSBCW). Adult calanoid copepods, Calanus sinicus, Paracalanus parvus s.l., Acartia omorii, and Centropages abdominalis were isolated by BVSTEP analysis based on the consistent explainable percentage (-32.3%) of the total mesozooplankton distributional pattern. The copepods, which accounted for 60 to 87% of the total abundances, occupied 73-78% of the copepod community. The YSBCW consistently remained in the northern part of the study area and influenced the spatial distribution of the calanoid copepods during the study periods. Abundances of C. sinicus and P. parvus s.l., which were high outside the YSBCW, were positively correlated with the whole water average temperature (p<0.01). In contrast, the abundances of C. abdominalis and A. omorii, which were relatively high in the YSBCW, were associated with the integrated chl-a concentration based on factor analysis. These results indicate that the YSBCW influenced the mesoscale spatial heterogeneity of average temperature and integrated chl-a concentration through the water column. This consequently affected the spatial distribution pattern of the dominant copepods in association with their respective preferences for environmental and biological parameters in the Yellow Sea during spring.

• 한국지리정보학회지
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• 제17권4호
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• pp.112-128
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• 2014

본 연구에서는 구미시를 사례로 매개 변수값의 변화에 따른 2SFCA(2 Step Floating Catchment Area) 기반 접근성 변화의 지역 특성을 분석하였다. 2SFCA는 기본인구가 증가하면 접근성이 감소하고, PPR(Provider to Population Ratio)이 증가하면 접근성이 증가하는 일반적인 경향을 보였다. 구미시 내부의 지역 특성을 분석하기 위해서 민감도 분석 과정에서 군집분석을 수행하였다. 지역 특성은 다음과 같다. 첫째, 구미시 읍면 외곽지역처럼 노인복지시설과 멀리 떨어져 있는 지역은 매개 변수값의 변화에 따른 접근성 변화가 미미하였다. 둘째, 기존 노인복지시설 주변 지역은 매개 변수값의 변화에 따라 접근성이 개선되거나 약화되는 다양한 양상을 보였다. 노인인구가 많고 노인복지시설이 밀집해 있는 동 지역에서는 PPR의 변화에 따른 접근성 변화가 크고, 나머지 지역은 기본인구 변화에 따른 접근성 변화가 크게 나타났다. 셋째, 매개 변수값이 커지면 여러 곳의 노인복지시설을 이용할 수 있는 구미시 중앙구역에서 전반적으로 접근성이 양호해지는 양상을 보였다. 향후, 2SFCA 기반의 접근성 분석 과정에서 매개 변수값 선택을 위한 신중한 시나리오 적용이 필요할 것이다.

• 대기
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• 제20권4호
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• pp.495-503
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• 2010

Satellite data have an intrinsic problem due to a number of various physical parameters, which can have a similar effect on measured radiance. Most evaluations of satellite performance have relied on comparisons with limited spatial and temporal resolution of ground-based measurements such as soundings and in-situ measurements. In order to overcome this problem, a new way of satellite data evaluation is suggested with statistical tools such as empirical orthogonal function(EOF), and singular value decomposition(SVD). The EOF analyses with OMI and OMI HCHO over northeast Asia show that the spatial pattern show high correlation with population density. This suggests that human activity is a major source of as well as HCHO over this region. However, this analysis is contradictory to the previous finding with GOME HCHO that biogenic activity is the main driving mechanism(Fu et al., 2007). To verify the source of HCHO over this region, we performed the EOF analyses with vegetation and HCHO distribution. The results showed no coherence in the spatial and temporal pattern between two factors. Rather, the additional SVD analysis between $NO_2$ and HCHO shows consistency in spatial and temporal coherence. This outcome suggests that the anthropogenic emission is the main source of HCHO over the region. We speculate that the previous study appears to be due to low temporal and spatial resolution of GOME measurements or uncertainty in model input data.

• 한국지형학회지
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• 제23권3호
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• pp.67-78
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• 2016

Soil carbon(C) is an essential property for characterizing soil quality. Understanding spatial patterns of soil C is particularly limited for mountain areas. This study aims to predict the spatial pattern of soil C using terrain analysis in a steep mountainous area. Specifically, model performances and prediction uncertainties were investigated based on the number of resampling repetitions. Further, important predictors for soil C were also identified. Finally, the spatial distribution of uncertainty was analyzed. A total of 91 soil samples were collected via conditioned latin hypercube sampling and a digital soil C map was developed using support vector regression which is one of the powerful machine learning methods. Results showed that there were no distinct differences of model performances depending on the number of repetitions except for 10-fold cross validation. For soil C, elevation and surface curvature were selected as important predictors by recursive feature elimination. Soil C showed higher values in higher elevation and concave slopes. The spatial pattern of soil C might possibly reflect lateral movement of water and materials along the surface configuration of the study area. The higher values of uncertainty in higher elevation and concave slopes might be related to geomorphological characteristics of the research area and the sampling design. This study is believed to provide a better understanding of the relationship between geomorphology and soil C in the mountainous ecosystem.

• 대한공간정보학회지
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• 제23권1호
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• pp.39-45
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• 2015

주택시장은 다양한 사회 경제적 특성에 의해 변화하며, 지역별 특성에 따라서도 상이하게 나타난다. 본 연구는 지역별 주택시장의 구조변화요인을 추출하고, 추출된 요인의 지역별 분포패턴을 분석하는데 목적이 있다. 이를 위해 첫째, 전국 251개 시 군 구 단위지역을 대상으로 2005~2010년의 5년간의 주택시장에 영향을 미치는 인구 사회 경제적 변수를 추출하였다. 이를 위해 인자분석을 실시하였다. 둘째, 공간통계인 크리깅기법을 이용하여 주택시장의 구조변화요인의 공간적 분포패턴을 파악하였다. 셋째, 통계적으로 유의미하게 집중 또는 분산되는 것인지, 아니면 무작위분포패턴을 보이는지의 여부를 파악하기 위해 공간적 자기상관 분석기법 중의 하나인 Moran I를 사용하였다.