• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2010.09a
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• pp.72-76
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• 2010

최근 들어 고해상도 항공영상을 활용한 공간정보의 구축 및 활용 사례가 증가하고 있으며, 기 구축된 공간정보의 정확도 향상을 위한 추가적인 노력이 필요시 되고 있는 실정이다. 이에 본 연구에서는 기존의 피해 전 후 항공영상을 이용한 피해지역 자동추출에 있어 결과물의 정확도 향상을 위하여 토지피복도와의 중첩을 통한 피해항목의 선택적 추출과 자동 추출된 결과물의 오차 제거가 가능하도록 하였다. 연구 대상지역은 2008년 7월 말 국지성 집중호우로 인하여 큰 피해를 입은 경상북도 봉화군 춘양면 일대를 선정하였으며, 집중호우에 상당히 취약하고 당시 사유시설 중 피해액이 가장 컸던 농경지에 대해 본 연구를 시범 적용하였다. 결과적으로 토지피복분류를 통해 피해 전 후 영상의 해상도 차이와 시계열적인 차이로 인해 발생하는 자동추출 결과물의 잡음 제거가 가능하였으며, 항공영상정보와 달리 육안으로 피해 항목의 선별이 어려운 자동추출 결과물에서 피해항목의 선별이 가능하였다. 이는 나아가 피해지역의 피해액 산출에 있어 보다 정확한 계산이 가능하게 하며, 추후 국가적 피해조사 사업에 있어 신뢰성 높은 피해정보 생산에 큰 기여를 할 것으로 사료된다.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.3
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• pp.97-104
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• 2010

The important factors in a flood simulation are hydrologic data (such as the rainfall and intensity), a threedimensional terrain model, and the hydrologic inundation calculation matrix. Should any of these factors lack accuracy, flood prediction data becomes unreliable and imprecise. The three-dimensional terrain model is constructed based on existing digital maps, current map updates, and airborne LiDAR data. This research analyzes and offers ways to improve the model's accuracy by comparing flood weakness areas selected according to the existing data on flood locations and design frequency.

• Spatial Information Research
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• v.19 no.3
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• pp.33-42
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• 2011

Since the method of generating 3D Spatial Information using aerial photographs was introduced, lots of researches on effective generation methods and applications have been performed. Nadir and oblique imagery are acquired in a same time by Pictometry system, and then 3D positioning is processed as Multi-Looking Camera procedure. In this procedure, the number of GCPs is the main factor which can affect the accuracy of true-orthoimage. In this study, 3D positioning accuracies of true-orthoimages which had been generated using various number of GCPs were estimated. Also, the standard of GCP number and distribution were proposed.

• Journal of Korean Society for Geospatial Information Science
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• v.10 no.4 s.22
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• pp.51-60
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• 2002

As the use of GIS becomes more widespread, the quality and source of data is becoming more of a concern among users. But accuracy is a component of quality, and the positional accuracy is a component of total accuracy. If only we consider the positional accuracy, simultaneously collecting technology of location and attribute information, whether it be manually, using conventional surveying method, GPS, or remote sensing, is a practical way of insuring that location and attribute information are correctly correlated. This study analyse the positional accuracy from a view-point of user and supplier, which is the considerations that can ensure quality level and continuously maintain the road and underground utility information. The positional accuracy of road and underground utility information are considered as two categories - expected accuracy of data collection procedure, required accuracy of data usage process. And the project manager must consider the cost/benefit view of data generation in order to determine the surveying method.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.4
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• pp.141-149
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• 2010

Three-dimensional geo-spatial information is important for the efficient use and management of the country and the three-dimensional expression and analysis of urban projects, such as urban plans devised by local governments and urban management. Thanks to the revitalization of the geo-spatial information service industry, it is now being variously used not only in public but also private areas. For the creation of high-guiltily three-dimensional geo-spatial information, emphasis should be placed on not only the quality of the source image and three-dimensional geo-spatial model but also the level of visualization, such as level of detail and texturing. However, in the case of existing three-dimensional geo-spatial information, its establishment process is complicated and its data are not updated frequently enough, as it uses ready-created digital maps. In addition, as it uses Ortho Images, the images exist Relief displacement. As a result, the visibility is low and the three-dimensional models of artificial features are simplified to reach LoD between 2 and 3, making the images look less realistic. Therefore, this paper, analyzed the quality of three-dimensional geo-spatial information created using the three-dimensional modeling technique were applied using Digital photogrammetry technique, using digital aerial photo images by an existing large-format digital camera and multi-looking camera. The analysis of the accuracy of visualization information of three-dimensional models showed that the source image alone, without other visualization information, secured the accuracy of 84% or more and that the establishment of three-dimensional spatial information carried out simultaneously with filming made it easier to gain the latest data. The analysis of the location accuracy of true Ortho images used in the work process showed that the location accuracy was better than the allowable horizontal position accuracy of 1:1,000 digital maps.

• Journal of the Society of Disaster Information
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• v.15 no.3
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• pp.427-439
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• 2019

Purpose: We generated geospatial information of unmanned aerial vehicle based on various SW and analyzed the location accuracy of orthoimage and DSM and texture mapping of 3D mesh. Method: The same unmanned aerial image data is processed using two different SW, and spatial information is generated. Among the generated spatial information, the orthoimage and DSM were compared with the spatial information generation results of the unmanned aerial photogrammetry SW by performing quantitative analysis by calculating RMSE of horizontal position and vertical position error and performing qualitative analysis. Results: There were no significant differences in the positional accuracy of the orthoimage and DSM generated by each SW, and differences in texture mapping in 3D mesh. The creation of the 3D mesh indicated the impact of the Unmanned Aerial Photogrammetry SW. Conclusion: It is shown that there is no effect of SW on the creation of orthoimage and DSM for geospatial analysis based on unmanned aerial vehicle. However, when 3D visualization is performed, texture mapping results are different depending on SW.

• The Journal of the Acoustical Society of Korea
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• v.28 no.6
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• pp.514-519
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• 2009

The projection approximation subspace tracking (PAST) is one of the attractive subspace tracking algorithms, because it estimates the signal subspace adaptively and continuously. Furthermore, the computational complexity is relatively low. However, the algorithm still has room for improvement in the subspace estimation accuracy. FE-PAST (Forward-Backward PAST) is one of the results from the improvement studies. In this paper, we propose a new algorithm to improve the orthogonality of the FB-PAST (Forward-Backward PAST).

• Korean Journal of Remote Sensing
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• v.36 no.5_3
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• pp.1013-1025
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• 2020

Unmanned Aerial Vehicle (UAV) platform is being widely used in disaster monitoring and smart city, having the advantage of being able to quickly acquire images in small areas at a low cost. Ground Control Points (GCPs) for positioning UAV images are essential to acquire cm-level accuracy when producing UAV-based orthoimages and Digital Surface Model (DSM). However, the on-site acquisition of GCPs takes considerable manpower and time. This research aims to provide an efficient and accurate way to replace the on-site GNSS surveying with three different sources of geospatial data. The three geospatial data used in this study is as follows; 1) 25 cm aerial orthoimages, and Digital Elevation Model (DEM) based on 1:1000 digital topographic map, 2) point cloud data acquired by Mobile Mapping System (MMS), and 3) hybrid point cloud data created by merging MMS data with UAV data. For each dataset a three-dimensional positional accuracy analysis of UAV-based orthoimage and DSM was performed by comparing differences in three-dimensional coordinates of independent check point obtained with those of the RTK-GNSS survey. The result shows the third case, in which MMS data and UAV data combined, to be the most accurate, showing an RMSE accuracy of 8.9 cm in horizontal and 24.5 cm in vertical, respectively. In addition, it has been shown that the distribution of geospatial GCPs has more sensitive on the vertical accuracy than on horizontal accuracy.

• 한국지형공간정보학회:학술대회논문집
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• 2004.10a
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• pp.161-166
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• 2004

• 한국공간정보시스템학회:학술대회논문집
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• 2007.06a
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• pp.273-279
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• 2007

환경분야에서 사용되는 대부분의 자료는 공간상 모든 위치에 그 값이 존재하나 모든 지점에서 자료를 획득하는 것이 불가능하므로 몇 개의 대표 지점에서 필요로 하는 자료를 수집한 후 이를 미관측 지역까지 확장하여 사용하게 된다. 관측된 자료를 이용하여 미관측 지점의 값을 예측하는 과정에는 공간보간 기법이 사용되는데, 본 논문에서는 지역경향면 모델, IDW, RBF, 크리깅 등의 공간보간 기법을 서울시의 미세먼지(PM10) 연평균 농도 공간보간에 적용하고 그 정확성을 살펴보았다. 정확성 평가를 위하여 예측값의 범위, RMSE, 평균오차 등을 살펴보았으며 이로부터 크리깅, RBF 기법의 예측 정확도가 높은 것으로 분석되었다.