• Journal of Korean Society for Geospatial Information Science
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• v.11 no.1 s.24
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• pp.71-75
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• 2003

The highway is greatly changed by the constant economic growth for a long times the traffic situation such as the large volumes and the performance vehicles, the performance enlargement of vehicles, the high speedization, etc., due to growth economic. A study of an optimal route selection model is researched over late 1980s by development of computer and GSIS, and consisted including research about the optimal route that uses digital terrain model in domestic such as the earth volume calculations, the mass curve output and the automation system construction. Lately, the study of the driving simulation of the highway and the virtual reality using VGIS(Virtual Geographic Information System) is researched. This study shows when the alternative highway selection considered surrounding facilities, development plan and according to estimate amount of traffic and the additional possibility of view analysis and environment effect analysis element will study through 3D simulation method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2D
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• pp.341-347
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• 2006

Geographically Imha basin is adjacent to Andong basin, but the occurrence of turbid water in each reservoir by storm events shows big differences. Hence, it is very important to identify the reason for these large differences. This study compared and analyzed soil erosion using the semi-empirical soil erosion model, RUSLE for both Imha and Andong basin, especially with emphasis on high-density turbid water. The agricultural district, which is the most vulnerable to soil erosion, was intensively analyzed based on land cover map produced by Ministry of Environment. As a result, the portion of the agricultural area is 11.88% for Andong basin, while it is 14.95% for Imha basin. Also all RUSLE factors excepts practice factor turned out to be higher for Imha basin. This means that the basin characteristics such as soil texture, terrain, and land cover for Imha basin is more vulnerable to soil erosion. Estimation of soil erosion by RUSLE for Andong and Imha basin is 1,275,806 ton and 1,501,608 ton, respectively, showing higher soil erosion by 225,802 ton for Imha basin.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5D
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• pp.741-747
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• 2008

Nowadays, the accuracy of the geoid model has been improved through development of the combination model which was composed of traditional gravimetric geoid and geometric geoid by the GPS/leveling data in USA and Japan. It is a state of the art method in geoid modeling field that what so called hybrid geoid. In this paper, as a basic study to develop Korean hybrid geoid model, we studied gravimetric geoid solutions using three gravity reduction methods (Helmert's condensation method, RTM method and Airy-isostatic method) and evaluated the usefulness of each method in context of precise geoid. The gravimetric geoid model were determined by restoring the gravity anomalies (included TC) and the indirect effects were made from various reduction methods on the EIGEN-CG03C reference field. The results are compared with respect to the geometric geoid undulation determined from 498 GPS/leveling after LSC fitting. The results showed that hybrid geoid with RTM (Residual terrain model) reduction method was most accurate method and the value of the difference compared to geometric geoid was $0.001{\pm}0.053m$.

• The Journal of Engineering Geology
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• v.17 no.1 s.50
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• pp.49-55
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• 2007

Various away methods are required in the electrical resistivity survey in order to find anomalous zone reliably. Array methods are classified as several groups. Among these group, a curved survey along the fixed elevation is designed to increase the mobility of men and survey equipments at the rough terrain. Another method is performed at the survey using inclined, curved, and horizontal boreholes. A survey can also be conducted in an arbitrary location by measurements of potentials for a multi sources. The complex data acquired using various away methods are represented by a correct images reconstructed from the 3D inversion. The element division is applied to the region in which the boreholes are curved and inclined because of a spatial discrepancies between the coordinate of each electrode and the nodal point in a model. The resistivity images are obtained from a good agreement for the anomalous zones in open slope and in survey using an inclined borehole.

• Journal of Korean Society of Rural Planning
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• v.27 no.4
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• pp.55-70
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• 2021

In this study, in the field of remote sensing, where the scope of application is rapidly expanding to fields such as land monitoring, disaster prediction, facility safety inspection, and maintenance of cultural properties, monitoring of rural space and surrounding environment using UAV is utilized. It was carried out to verify the possibility, and the following main results were derived. First, the aerial image taken with an unmanned aerial vehicle had a much higher image size and spatial resolution than the aerial image provided by the National Geographic Information Service. It was suitable for analysis due to its high accuracy. Second, the more the number of photographed photos and the more complex the terrain features, the more the point cloud included in the aerial image taken with the UAV was extracted. As the amount of point cloud increases, accurate 3D mapping is possible, For accurate 3D mapping, it is judged that a point cloud acquisition method for difficult-to-photograph parts in the air is required. Third, 3D mapping technology using point cloud is effective for monitoring rural space and rural resources because it enables observation and comparison of parts that cannot be read from general aerial images. Fourth, the digital elevation model(DEM) produced with aerial image taken with an UAV can visually express the altitude and shape of the topography of the study site, so it can be used as data to predict the effects of topographical changes due to changes in rural space. Therefore, it is possible to utilize various results using the data included in the aerial image taken by the UAV. In this study, the superiority of images acquired by UAV was verified by comparison with existing images, and the effect of 3D mapping on rural space monitoring was visually analyzed. If various types of spatial data such as GIS analysis and topographic map production are collected and utilized using data that can be acquired by unmanned aerial vehicles, it is expected to be used as basic data for rural planning to maintain and preserve the rural environment.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.3
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• pp.231-238
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• 2007

This paper describes the availability of the forthcoming integrated GNSS(Global Navigation Positioning System) positioning that includes GPS(Global Positioning System), Galileo, and QZSS(Quasi-Zenith Satellites System). We built a signal propagation model that identifies direct, multipath, and diffraction signals, using the principles of specular reflection and ray tracing technique. The signal propagation model was combined with 3D GIS(three-dimensional geographic information system) in order to measure the satellite visibility and positioning error factors, such as the number of visible satellites, average elevation of visible satellites, optimized DOP(dilution of position) values, and the portion of multipath-producing satellites. Since Galileo and QZSS will not be fully operational until 2010, we used a simulation in comparing GPS and GNSS positioning for a $1km{\times}1km$ developed area in Shinjuku, Tokyo. To account for local terrain variation. we divided the target area into 40,000 $5m{\times}5m$ grid cells. The number of visible satellites and that of multipath-free satellites will be greatly increased in the integrated GNSS environment while the average elevation of visible satellites will be higher in the GPS positioning. Much decreased PDOP(position dilution of precision) values indicate the appropriate satellite/user geometry of the integrated GNSS; however, in dense urban areas, multipath mitigation will be more important than the satellite/user geometry. Thus, the efforts for applying current technologies of multipath mitigation to the future GNSS environment will be necessary.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.4
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• pp.186-192
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• 2005

We investigated the deposition characteristics and mass transport flux estimation of the Nakdong estuary, Korea. To understand the effects of the tidal current circulation that influences estuary terrain changes, we used a 2D numerical model to map seawater circulation under three different situations, with the level of river flow being set as none or flood. The net-water flux of the cross-sectional area between sandbars (known as dung) was estimated. From our review of previous research, we know that the development of local sandbars shifted from the west to the east side of the estuary after the construction of the Nakdong River dike. Current development is occurring mostly at the Bakhap-dung near Tadea. The seawater circulation pattern over this large-scale area of tidal na is brings changes related to the quantity of the outflow from the Nakdong River. Based on the calculated results for the net-water flux of the cross-sectional area, we see very strong accumulation in local waters around Jangjiado, Bakhapdung, and Tadae under flood river flow conditions, but accumulation in local waters around Jinudo under the other states of flow. Consequently, in the Nakdong estuary, the main sensitive regions that are affected by changes in the flow of river discharge are the local waters around Jangiado, Bakhapdung, Tadae, and Jinudo.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.20 no.2
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• pp.127-136
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• 2002

DEM(Digital Elevation Model) is used widely in image processing, water resources, construction, GIS, landscape architecture, telecommunication, military operations and other related areas. And it is used especially in producing ortho-photo based on specific DEM and developing 3D GIS database vividly. As LiDAR(Light and Detection And Ranging) system emerged recently, DEM could be developed in urban area more efficiently and more economically, compared to the conventional DEM Production. Traditional method using check points for elevation has tome limitations in structure's height accuracy by LiDAR, because it uses only terrain height. Accordingly after the downtown of Chungju city was selected as a test field in this paper and DEM and digital ortho images was produced by way of LiDar survey, the accuracy was evaluated through analytical plotting map. The result shows that in case of buildings in LiDAR DEM, the accuracy is 0.30 m in X, 0.62 m in Y and RMS is 1.17 m. The difference distribution between DEM and plotting map in range of $\pm$10 cm was 36.2% and $\pm$10 cm $\pm$20 cm was 43.53%. The accuracy of LiDAR in this study meets 1/5,000 which is the regulation for map of NGI(National Geography Institute) and LiDAR can be possibly used in many other applied area.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.4
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• pp.363-373
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• 2020

During last decades numerous studies generating orthoimage have been carried out. Traditional methods require exterior orientation parameters of aerial images and precise 3D object modeling data and DTM (Digital Terrain Model) to detect and recover occlusion areas. Furthermore, it is challenging task to automate the complicated process. In this paper, we proposed a new concept of true orthoimage generation using DL (Deep Learning). DL is rapidly used in wide range of fields. In particular, GAN (Generative Adversarial Network) is one of the DL models for various tasks in imaging processing and computer vision. The generator tries to produce results similar to the real images, while discriminator judges fake and real images until the results are satisfied. Such mutually adversarial mechanism improves quality of the results. Experiments were performed using GAN-based Pix2Pix model by utilizing IR (Infrared) orthoimages, intensity from LiDAR data provided by the German Society for Photogrammetry, Remote Sensing and Geoinformation (DGPF) through the ISPRS (International Society for Photogrammetry and Remote Sensing). Two approaches were implemented: (1) One-step training with intensity data and high resolution orthoimages, (2) Recursive training with intensity data and color-coded low resolution intensity images for progressive enhancement of the results. Two methods provided similar quality based on FID (Fréchet Inception Distance) measures. However, if quality of the input data is close to the target image, better results could be obtained by increasing epoch. This paper is an early experimental study for feasibility of DL-based true orthoimage generation and further improvement would be necessary.