• 한국지리정보학회지
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• 제15권4호
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• pp.90-103
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• 2012

만리포는 2007년 12월 허베이 스피리트호 유류유출 사고로 유류오염 피해를 입은 대표적인 해변이다. 본 연구는 만리포 전체 영역과 5개로 분할된 영역을 대상으로 유분(TPH: Total Petroleum Hydrocarbon)의 시 공간적 변화 패턴에 대해 두 계절(동계와 하계)의 차이를 비교하고자 한다. 만리포 전체 영역에서 4년간 시간에 따른 유분농도의 감소율은 동계가 하계보다 약 두 배 크게 나타났다. 유분농도의 가중공간중심(weighted mean center)과 가중표준거리(weighted standard distance)를 이용한 유분분포의 공간적 변화 패턴 분석 결과, 동계에는 유분이 만리포의 남서 해변으로 군집된 패턴을 보인 반면, 하계에는 전 영역으로 분산된 패턴을 보였다. 만리포 내 분할 영역에서 유분의 시간적 변동은 동계에 모든 영역에서 농도가 지속적으로 감소한 반면, 하계에는 2009년 이후 남서 해변을 제외한 모든 영역에서 농도 변화를 보이지 않았다. 따라서 유류오염의 진행 상황을 평가하고 예측하기 위해서는 동계와 하계와 같이 시기를 구분하여 공간분석 기법을 이용한 유분의 시 공간 변동 패턴 분석이 필요하다. 또한, 지역적으로 불균등한 유분분포의 시간적 변동 패턴을 해석하기 위해서는 전체 해변에서 보다는 공간분할을 통한 지역 규모에서의 시계열적 분석이 유용하다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 추계종합학술대회
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• pp.457-461
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• 2007

In many applications, received signal strength indicator is used for location tracking and sensor nodes localization. For location finding, the distances between sensor nodes can be estimated by converting received signal's power into distance using path loss prediction model. Many researches have done the analysis of power-distance relationship for radio channel characterization. In indoor environment, the general conclusion is the non-linear variation of RSSI values as distance varied linearly. This has been one of the difficulties for indoor localization. This paper presents works on indoor RSSI characterization based on statistical methods to find the overall trend of RSSI variation at different places and times within the same room From experiments, it has been shown that the variation of RSSI values can be determined by both spatial and temporal factors. This two factors are directly indicated by the two main parameters of path loss prediction model. The results show that all sensor nodes which are located at different places share the same characterization value for the temporal parameter whereas different values for the spatial parameters. Using this relationship, the characterization for location estimation can be more efficient and accurate.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.691-695
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• 2004

In recent years, mary studies for efact estimation of groudwater recharge has been performed. They can be categorized into three groups : analytical method by means of groundwater recession curve, water budget analysis based on watershed, and the method using groundwater model. Since groundwater recharge rate shows the spatial-temporal variability due to hydrogeological heterogeneity, existing studies have various limits to deal with these characteristics. The method of estimating daily recharge rate with spatial-temporal variation based on rainfall-runoff model is suggested in this study for this purpose. This method is expected to enhance existing indirect method by means of reflecting climatic conditions, land use and hydrogeological heterogeneity.

• 자원환경지질
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• 제36권5호
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• pp.329-338
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• 2003

이 연구는 무주군 적상산 부근에 위치하는 소유역(100$Km^2$)에서 지표수와 천부 지하수의 안정동위원소 조성의 시공간적 변화를 조사하기 위해서 실시되었다. 시료채취는 2001년 8월(여름)과 10월(가을), 2002년 4월(봄), 3회에 걸쳐 실시되었다. 지표수의 동위원소 조성은 계절에 따라 뚜렷이 구분되어 도시되지만 천부 지하수에서는 이러한 변화가 줄어든 것이 관찰되었다. 하지만 지표수와 지하수의 안정동위원소 조성의 변화 폭은 계절별로 서로 유사하게 나타나고 있다. 이것은 이 지역에서 강수, 지표수 및 지하수 사이의 상호작용이 매우 활발하며 지속적으로 일어나고 있음을 의미한다. 무주지역 지표수의 안정동위원소 조성은 남쪽에 위치하는 섬진강의 조성보다는 가벼운 “위도효과”를 나타내고 있다. 또한 하천수에는 동위원소 조성의 계절변화와 아울러 강수의 “고도효과”와 “우량효과”가 잘 반영되어 있음이 관찰되었다.

• 한국환경생물학회:학술대회논문집
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• 한국환경생물학회 2002년도 춘계공동학술대회 및 심포지움 초록집
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• pp.44-44
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• 2002

• 한국대기환경학회지
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• 제32권1호
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• pp.114-126
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• 2016

Many cohort studies have reported associations of individual-level long-term exposures to $PM_{10}$ and health outcomes. Individual exposures were often estimated by using exposure prediction models relying on $PM_{10}$ data measured at national regulatory monitoring sites. This study explored spatial and temporal characteristics of regulatory $PM_{10}$ measurement data in South Korea and suggested $PM_{10}$ concentration metrics as long-term exposures for assessing health effects in cohort studies. We obtained hourly $PM_{10}$ data from the National Institute of Environmental Research for 2001~2012 in South Korea. We investigated spatial distribution of monitoring sites using the density and proximity in each of the 16 metropolitan cities and provinces. The temporal characteristics of $PM_{10}$ measurement data were examined by annual/seasonal/diurnal patterns across urban background monitoring sites after excluding Asian dust days. For spatial characteristics of $PM_{10}$ measurement data, we computed coefficient of variation (CV) and coefficient of divergence (COD). Based on temporal and spatial investigation, we suggested preferred long-term metrics for cohort studies. In 2010, 294 urban background monitoring sites were located in South Korea with a site over an area of $415.0km^2$ and distant from another site by 31.0 km on average. Annual average $PM_{10}$ concentrations decreased by 19.8% from 2001 to 2012, and seasonal $PM_{10}$ patterns were consistent over study years with higher concentrations in spring and winter. Spatial variability was relatively small with 6~19% of CV and 21~46% of COD across 16 metropolitan cities and provinces in 2010. To maximize spatial coverage and reflect temporal and spatial distributions, our suggestion for $PM_{10}$ metrics representing long-term exposures was the average for one or multiple years after 2009. This study provides the knowledge of all available $PM_{10}$ data measured at national regulatory monitoring sites in South Korea and the insight of the plausible longterm exposure metric for cohort studies.

• 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).

• 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.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권3호
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• pp.1595-1613
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• 2017

The IR camera and laser-based IR projector provide an effective solution for real-time collection of moving targets in RGB-D videos. Different from the traditional RGB videos, the captured depth videos are not affected by the illumination variation. In this paper, we propose a novel feature extraction framework to describe human activities based on the above optical video capturing method, namely spatial-temporal texture features for 3D human activity recognition. Spatial-temporal texture feature with depth information is insensitive to illumination and occlusions, and efficient for fine-motion description. The framework of our proposed algorithm begins with video acquisition based on laser projection, video preprocessing with visual background extraction and obtains spatial-temporal key images. Then, the texture features encoded from key images are used to generate discriminative features for human activity information. The experimental results based on the different databases and practical scenarios demonstrate the effectiveness of our proposed algorithm for the large-scale data sets.

• Journal of the Korean Data and Information Science Society
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• 제28권1호
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• pp.173-183
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• 2017

본 연구는 아파트 개별 실거래가격에 대한 시공간 자료를 활용하여 아파트 매매가격에 영향을 미치는 요인을 시계열적 흐름과 공간적 변화를 반영한 지리시간가중 회귀모형 (geographical temporal weighted regression; GTWR)모형을 적용하여 분석하였다. 기존 연구에서 활용되었던 일반적인 접근방법인 최소제곱 (ordinary least square; OLS) 회귀모형과 공간 데이터를 분석하기 위한 공간계량 모델 중 가장 많이 활용되고 있는 지리가중 회귀모형 (geographically weighted regression;GWR)과 달리 GTWR은 주택가격 특성을 고려함에 있어서 시간과 공간을 함께 고려함으로써 보다 정밀한 평가모형이 될 것으로 기대되었다. 본 연구에 사용된 주택가격결정 설명 요인들 중에서 건축연도 및 전용면적이 주택가격을 결정하는데 유의적인 영향을 미치는 것으로 나타났으며, 주택가격이 시간적 공간적 특성 모두에 의하여 유의적으로 설명되었다.