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방건준,이진덕 한국측량학회 2017 한국측량학회지 Vol.35 No.4
UHI (Urban Heat Island) is an important environmental issue occurring in highly developed (or urbanized) area such as Seoul Metropolitan City of Korea due to modification of the land surface by man-made structures. With the advance of the remote sensing technique, land cover types and LST (Land Surface Temperature) influencing UHI were frequently investigated describing that they have a positive relationship. However, the concept of land cover considers material characteristics of the urban cover in a comprehensive way and does not provide information on how human activities influence on LST in detail. Instead, land use reflects ways of land use management and human life patterns and behaviors, and explains the relationship with human activities in more details. Using this concept, LST was segmented according to land use types from the Landsat imagery to identify the human-induced heat from the surface and interannual and seasonal variation of LST with GIS. The result showed that the LST intensity of Seoul was greatest in the industrial area and followed by the commercial and residential areas. In terms of size, the residential area could be defined as the major contributor among six urban land use types (i.e., residential, industrial, commercial, transportation, etc.) affecting UHI during daytime in Seoul. For temperature, the industrial area was highest and could be defined as a major contributor. It was found that land use type was more appropriate to understand the human-induced effect on LST rather than land cover. Also, there was no significant change in the interannual pattern of LST in Seoul but the seasonal difference provided a trigger that the human life pattern could be identified from the satellite-derived LST.
방건준,이진덕 한국측량학회 2017 한국측량학회지 Vol.35 No.1
NDVI (Normalized Difference Vegetation Index) plays an important role in surface land cover classification and LST (Land Surface Temperature Extraction). Its characteristics do not full carry the information of the surface cover typically in urban areas even though it is widely used in analyses in urban areas as well as in vegetation. However, abnormal NDVI values are frequently found in urban areas. We, therefore, examined NDVI values on whether NDVI is appropriate for LST and whether there are considerations in NDVI analysis typically in urban areas because NDVI is strongly related to the surface emissivity calculation. For the study, we observed the influence of the surface settings (i.e., geometric shape and color) on NDVI values in urban area and transition features between three land cover types, vegetation, urban materials, and water. Interestingly, there were many abnormal NDVI values systematically derived by the surface settings and they might influence on NDVI and eventually LST. Also, there were distinguishable transitions based on the mixture of three surface materials. A transition scenario was described that there are three transition types of mixture (urban materialvegetation, urban material-water, and vegetation-water) based on the relationship of NDVI and LST even though they are widely distributed.
방건준(Kon Joon Bhang),이진덕(Jin-duk Lee) 한국콘텐츠학회 2014 한국콘텐츠학회논문지 Vol.14 No.12
최근 이상기후로 인한 다양한 자연재해로 광역적 수문 모니터링이 매우 중요하게 되었다. 본 연구에서는 광역적 수문 모니터링을 위한 기초자료 조사 방법으로 원격탐사기법을 적용하여 날씨에 영향을 받지 않는 SAR 원격탐사 기술에 기반한 수위 추출 방법을 팔당호와 미국 미네소타지역의 호수에 적용하였다. SAR를 이용한 수위추출 기법 적용을 위해 SAR 영상에서 얻어진 SRTM DEM을 사례로 SAR기반 DEM 자료의 특성을 관찰하고, 평균과 등고선을 이용한 수위추출 방법을 제시하여 SAR 영상의 적용 가능성을 제시하였다. 결과적으로 수위 추출에서 SAR 영상을 통해 얻어진 DEM은 실제 지표보다 낮게 관측되어 지역고도 편차를 갖고 있는 것을 알 수 있으며, 등고선을 적용해 사용자가 경험을 통해 수위를 0.5m 이내 수준의 오차로 추출할 수 있음을 보였다. Regional hydrological monitoring has been an important issue due to recent climate change causing natural disaster. As a basic data collection method for water resources monitoring in a large area, the lake stage extraction method which is based on the SAR remote sensing technique independent on weather conditions was applied for the Paldang Reservoir in Korea and lakes in Minnesota, the U.S. To implement the lake stage extraction method with stereo SAR images, we observed characteristics of stereo SAR image based DEM data with SRTM DEM and proposed average and contouring methods for lake stage extraction. The applicability of SAR imagery in lake stage extraction was presented as well. As a result, the study showed that SAR-derived DEM has a local bias which means the elevations are lower than the true ground levels and operators could extract lake levels with errors of less than 0.5m using contouring depending on their experience.