• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.372-372
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• 2022

스마트시티 하천관리를 위해 선행된 연구에서는 도시하천관련 데이터를 수집-정제-제공하는 도시하천 통합데이터 플랫폼을 개발하였다. 이에 하천 분석을 위한 유역 유출, 하천 흐름 그리고 도시유출 등의 모듈과 하천 환경, 친수, 종합 평가 모델을 연계하여 도시하천관리 연계플랫폼으로 연구개발을 진행하였다. 본 연구에서는 스마트시티 하천관리를 위한 시나리오 기반 제방 파제 시뮬레이션 분석 결과 가시화 모듈에 관한 연구를 진행한다. 부산 EDC 지역을 대상으로 DEM, 항공영상, 위성영상, 하천 지리 정보, 하천 단면도 등의 데이터를 결합하여 하천 및 유역 전산 3D 형상 모델링을 진행한다. 또한 하천 내부 유량 및 파제 제체 모델링, 유동장 격자 모델링을 통해 제방 붕괴 범람 시뮬레이션 대상 지역을 구현한다. 해당 EDC 지역 구현 모델에 연속방정식, 운동량방정식, 수송방정식 등 지배방정식과 삼상 유동 기법 등 수치 해석 기법을 활용하여 제방 파제 시뮬레이션을 수행한다. 시뮬레이션의 침수범위 및 침수심 분포 결과는 위경도를 포함한 ASCII Grid로 반환되며 GeoServer를 통한 좌표계 설정 및 도시하천 연계플랫폼에서 가시화하는 연구를 진행하였다. 제방 파제 시나리오는 제방 높이 2m, 제방 폭 7.5m, 파제 길이 20m로 설정하여 4개의 붕괴 위치를 지정하였고, 지정된 위치에 대한 제방 파제 3D 시뮬레이션을 통해 도출된 Case 별 2D/3D 영상과 침수심 공간 분포에 대한 Raster Graphics를 전처리하여 시나리오별 침수범위-침수심을 도시하천 연계플랫폼 상에서 가시화하는 연구를 진행하였다. 도시하천 연계플랫폼의 시나리오 기반 제방 파제 시뮬레이션 모듈을 통하여 스마트시티의 제방 파제 피해 양상 및 대책 마련 의사결정 보조로 활용할 수 있을 것으로 기대된다.

• Korean Journal of Remote Sensing
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• v.39 no.5_3
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• pp.1009-1029
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• 2023

Urban trees play a vital role in urban ecosystems,significantly reducing impervious surfaces and impacting carbon cycling within the city. Although previous research has demonstrated the efficacy of employing artificial intelligence in conjunction with airborne light detection and ranging (LiDAR) data to generate urban tree information, the availability and cost constraints associated with LiDAR data pose limitations. Consequently, this study employed freely accessible, high-resolution multispectral satellite imagery (i.e., Sentinel-2 data) to estimate fractional tree canopy cover (FTC) within the urban confines of Suwon, South Korea, employing machine learning techniques. This study leveraged a median composite image derived from a time series of Sentinel-2 images. In order to account for the diverse land cover found in urban areas, the model incorporated three types of input variables: average (mean) and standard deviation (std) values within a 30-meter grid from 10 m resolution of optical indices from Sentinel-2, and fractional coverage for distinct land cover classes within 30 m grids from the existing level 3 land cover map. Four schemes with different combinations of input variables were compared. Notably, when all three factors (i.e., mean, std, and fractional cover) were used to consider the variation of landcover in urban areas(Scheme 4, S4), the machine learning model exhibited improved performance compared to using only the mean of optical indices (Scheme 1). Of the various models proposed, the random forest (RF) model with S4 demonstrated the most remarkable performance, achieving R² of 0.8196, and mean absolute error (MAE) of 0.0749, and a root mean squared error (RMSE) of 0.1022. The std variable exhibited the highest impact on model outputs within the heterogeneous land covers based on the variable importance analysis. This trained RF model with S4 was then applied to the entire Suwon region, consistently delivering robust results with an R² of 0.8702, MAE of 0.0873, and RMSE of 0.1335. The FTC estimation method developed in this study is expected to offer advantages for application in various regions, providing fundamental data for a better understanding of carbon dynamics in urban ecosystems in the future.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.06a
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• pp.29-32
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• 2016

특징점 기반 건물인식 시스템에서는 강건한 특징점을 추출하는 것이 인식률 향상에 바로 직결되는 중요한 요소이다. 영상에서 특징점들이 너무 많이 추출되는 경우 인식이나 학습단계에서의 알고리즘 수행 시간을 증가시키는 원인이 된다. 또환 중요하지 않은 특징점(배경이나 가려짐 영역, 기타 객체에서 추출된 특징점)이나 조명 변화에 민감한 영역에서 임의로(arbitrarily) 추출된 특징점은 인식률을 저하시키는 문제를 발생시킨다. 특히 도시환경에서 촬영된 영상의 특징점을 추출할 때 이러한 문제 현상들이 빈번하게 발생한다. 본 논문에서는 이러한 문제를 해결하고자 multi-view 영상에서 건물의 homography를 기반으로 정확히 정합된 특징점인 inlier만을 선택하는 알고리즘을 제안한다. Inlier로 분류된 특징점들은 건물 인식 시스템을 구성하기 위해 사용되고 조명 변화에 민감한 영역에서 임의로 추출된 특징점들은 영역 기반 특징을 추출하여 건물 인식 시스템의 인식률을 높인다. 또한 이를 이용하여 인식하고자 하는 건물과의 상관관계가 적은 잉여 영상들을 DB에서 제거하는 방법도 제안한다. 실험을 통하여 제안하는 기법의 우수성을 보였다.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.3
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• pp.1-16
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• 2022

Areas developed through land reclamation projects have huge economic advantages in terms of supplying lands that can be used for farmlands, urban areas and etc., however have relatively small areas of grasslands and densely located buildings compared to inland cities. Hence, an urban heat island is occurring in these areas due to this characteristic, and in particular, the urban heat island in Cheongna International City is getting serious. In this study, the urban heat island in Cheongna International City was evaluated and analyzed by classified into the three periods after the reclamation project: farmland(2001-2008), development(2009-2013) and artificial grassland(2014-2020). The land cover map and Landsat time-series imagery were utilized for measuring the differences of the land surface temperatures between the urbanized areas and the grassland/forest areas in Cheongna International City. The statistical results showed that the differences in the land surface temperature between these areas were calculated to be at most 0℃ during the period of farmland, at most 3.60℃ during the period of development, and at most 2.51℃ during the period of grassland. This study proved that the urban heat island phenomenon increased when the urbanized areas increased, and the urban heat island phenomenon decreased when the artificial grassland areas increased in Cheongna International City where the reclamation project was carried out. The statistical results derived through this research can be used as the reference data for identifying the urban heat island problem in urban planning and establishing the reduction plan.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2017.11a
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• pp.107-108
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• 2017

도시재생사업의 성공적 완수를 위해 드론을 활용하여 항공촬영정사영상 실태조사 지원하고 관리시스템을 구축하여 도시재생사업의 원활한 추진을 돕는다.

• Korean Journal of Remote Sensing
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• v.36 no.6_2
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• pp.1579-1590
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• 2020

In this paper, spatially-adaptive denormalization (SPADE) based U-Net is proposed to detect changes by using high-resolution satellite images. The proposed network is to preserve spatial information using SPADE. Change detection methods using high-resolution satellite images can be used to resolve various urban problems such as city planning and forecasting. For using pixel-based change detection, which is a conventional method such as Iteratively Reweighted-Multivariate Alteration Detection (IR-MAD), unchanged areas will be detected as changing areas because changes in pixels are sensitive to the state of the environment such as seasonal changes between images. Therefore, in this paper, to precisely detect the changes of the objects that consist of the city in time-series satellite images, the semantic spatial objects that consist of the city are defined, extracted through deep learning based image segmentation, and then analyzed the changes between areas to carry out change detection. The semantic objects for analyzing changes were defined as six classes: building, road, farmland, vinyl house, forest area, and waterside area. Each network model learned with KOMPSAT-3A satellite images performs a change detection for the time-series KOMPSAT-3 satellite images. For objective assessments for change detection, we use F1-score, kappa. We found that the proposed method gives a better performance compared to U-Net and UNet++ by achieving an average F1-score of 0.77, kappa of 77.29.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2004.03a
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• pp.565-570
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• 2004

우리나라는 1960년대부터 산업발전과 함께, 급속한 도시화가 이루어졌다. 현재 활용 가능한 위성영상은 1975년 이후에 얻어진 영상이기 때문에 미국에서 1995년 일반에 공개된 DSI (Declassified Satellite Imagery) 영상은 1960년대 한반도의 지형정보를 제공하는 유일한 위성영상 자료이며 DSI 중 해상포가 2m 급에 이르는 CORONA 영상은 도시, 산림 환경의 변화를 탐지하는데 매우 유용하다. 본 논문에서의 과거의 한반도를 영상지도로 만들기 위해 모자이크 영상을 제작하였으며 모자이크 영상을 제작하기 위한 기하보정 방법에 대해 비교 분석하였다. 또한 최근 공개된 KH-9 영상을 기하보정하고 정확도를 분석하였다.

• Journal of Korean Society for Geospatial Information Science
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• v.11 no.2 s.25
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• pp.17-28
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• 2003

Since 1970s, Seoul Metropolitan Area has been growing in physical and demographic aspect. A number of new urban fringes, New City, had been particularly developed from the early of 1990s. To examine the urban growth, the population density maps are generally used to the efficient urban management tool. The density maps from political boundaries, however, were traditionally used to estimate an urban concentration, there is problems to apply directly to urban management decision making due to (i) the abrupt changes between boundaries and (ii) the inclusion of green areas and forests in these areas. The mass-preserving interpolation method, the Pycnophylactic interpolation, could provide more realistic density maps. In addition, the classified urban areas from satellite images corresponding years would turn out to be more reliable results since populations were only applied to urbanized areas. Even though the Pyconophylactic method makes the density larger, it would be useful to produce a general urban growth trend at large scale. Consequently, four different density maps are compared and reviewed for this study, and the cross-sectional analysis provided to glimpse of population density around the city center.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6478-6483
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• 2014

Media facades project images on the external walls of a building as a screen. Such facades can recover the cultural emotions of users tired of a high level of market competition in urban spaces and develop into urban aesthetics and be reinterpreted as an image design as the city becomes a topic as well as the target projected. From a cultural perspective, the artistic possibility and strengthening of publicness of media facades are discussed. One of the considerations is that it should be the medium communicating with the building or surrounding of the projected target. Urban landscape media facades, such as 2014 Gwanghwamun media facade, 2014 Sejong Center for the Performing Arts media facade and 2013 Namsan media facade were compared and analyzed. As a result, four types of image design components could be derived such as motifs, concepts, stories and projection types. Media facade, which is establishing itself as a new technological genre beyond canvas and theater screens, should contain messages, themes and technological advances as a higher level of the urban symbolic art form in the future. This paper derived the components of image design through the comparative analysis of symbolic urban landscape media facade.

• Spatial Information Research
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• v.11 no.4
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• pp.509-518
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• 2003

Impervious surface affects urban climate, flood, and water pollution. With a higher paved rate, expanded heat containing capacity of buildings and roads raises atmospheric temperature, and increased quantity of the outflowed water brings flood during a heavy downpour. Moreover, increased non-point source pollutant load is accountable for water pollution. In this regard, it is definitely important to research and keep monitoring the current situation of paved surface, which influences urban ecosystem, disaster and pollution. In fact, collecting information on urban paved surface, which requires the time and expense, is very difficult due to its complicate structure. In order to solve the problem, this study suggested a method to utilize satellite image data for efficient survey on the current condition of paved surface. It analyzed the paved surface condition of Anyang-si by using IKONOS image and discussed the usefulness and limitation of this method.