• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.4
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• pp.391-399
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• 2020

Autonomous driving can be limited by only using sensors if the sensor is blocked by sudden changes in surrounding environments or large features such as heavy vehicles. In order to overcome the limitations, the precise road-map has been used additionally. In korea, the NGII (National Geographic Information Institute) produces and supplies high definition map for autonomous vehicles. Accordingly, in this study, errors occurring in the process of e data editing and dtructured esditing of high definition map are systematically typed providing by the National Geographic Information Institute. In addition, by presenting the error search process and solution for each situation, we conducted a study to quickly correct errors in high definition map, and largely classify the error items for shape integrity, spatial relationship, and reference relationship, and examine them in detail. The method was derived.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.7
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• pp.3-12
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• 2004

The need to predict the rate of soil erosion, both under existing conditions and those expected to occur following soil conservation practice, has been led to the development of various models. In this study Morgan model especially developed for field-sized areas on hill slopes was applied to assess the rate of soil erosion using RS/GIS environment in the Dukchun river basin, one of two tributaries flowing into Jinyang lake. In order to run the model, land cover mapping was made by the supervised classification method with Landsat TM satellite image data, the digital soil map was generated from scanning and screen digitizing from the hard copy of soil maps, digital elevation map (DEM) in order to generate the slope map was made by the digital map (DM) produced by National Geographic Information Institute (NGII). Almost all model parameters were generated to the multiple raster data layers, and the map calculation was made by the raster based GIS software, IL WIS which was developed by ITC, the Netherlands. Model results show that the annual soil loss rates are 5.2, 18.4, 30.3, 58.2 and 60.2 ton/ha/year in forest, paddy fields, built-up area, bare soil, and upland fields respectively. The estimated rates seemed to be high under the normal climatic conditions because of exaggerated land slopes due to DEM generation using 100 m contour interval. However, the results were worthwhile to estimate soil loss in hilly areas and the more precise result could be expected when the more accurate slope data is available.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.2
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• pp.13-20
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• 2010

Currently, NGII(National Geographic Information Institute) provides VRS(Virtual Reference System) service using 44 CORS(Continuously Operating Reference Stations). Since the VRS provides high-precision coordinate in a short time, the users and applications are expected to be rapidly increasing. The accuracy analysis on the VRS service, however, was not sufficiently performed yet. Therefore, in this study, the VRS data is acquired from various circumstances and its accuracy is analyzed. According to analysis, it was concluded that the VRS could be applied to public control point survey. Furthermore, it was found that the PQ(Position Quality) which represents variance of estimated coordinates rather than GDOP(Geometric Dilution of Precision) is more relevant as a factor to determine the accuracy of coordinates. Based on the analysis of data from four manufacturers (TRIMBLE, MAGELLAN, LECIA, TOPCON), it was confirmed that the standard deviations better than 3cm. Therefore, VRS Survey apply to public control point survey.

• Journal of Korean Society for Geospatial Information Science
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• v.24 no.3
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• pp.85-92
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• 2016

Slope is one of the most important factor in land development permission standards. In guideline of "Land Suitability Assessment" or "Forest Land Conversion Standard", average slope can be measured using digital map and GIS for target area. Inputs in slope calculation are 1/5,000 digital map of NGII(National Geographic Information Institute) or digital information of Korea Land Information System. Many confusions occur in the field, as there is no standard for slope calculation and are lots of slope calculation methods using contour lines or DEM derived from them. Avoiding these confusions, this study was intended to propose a standardized method for slope calculation and a selection method for a suitable resolution. In this study, using DEM of optimum grid size according to the complexity of topography with finite difference method is suggested as improved slope calculation method, after comparing several representative slope calculation methods.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.1 s.35
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• pp.65-74
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• 2006

A rapidly developed satellite technology is used in comprehensive fields such as spatial data aquisition and applications. Especially a GPS positioning is expected to reinvigorate at the national reference system changes to ITRF(International Terrain Reference Frame). Currently the National Geographic Information Institute(NGII) issues a triangulation point coordinate by separating old and new coordinates and in the year of 2007 it will be scheduled to be changed ITRF. The triangulation point coordinate in Cheju area causes some problems due to the difference original observation and re-observation. Thus in this study a GPS observation is conducted after re-organizing geodetic network based on 1st and 2nd order triangulation in order to check the current triangulation points in Cheju area. After the GPS observation data analysis, stable points were extracted, proposed a geodetic network and its application.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.7
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• pp.1588-1596
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• 2004

Recently, many WMS(Web Mapping Services) and POI(Point of Interest) service on to be in service on the Internet using Web CIS(Geographic Information System) as information Technology and computer HW are evolved faster in its speed, network bandwidth and features. The Web GIS is, however, limited and constrained on the specification of its system configuration, the service class provided and the presentation methodology of a map. As the mobile Internet becomes popular in mobile service, Web GIS service on mobile environment is strongly required and to be provided by LBS(Location Based Service) on a mobile client such as PDA with location information of the user. In this paper, we made an effort to design and implement a GIS computing environment by thin client for mobile web mapping service. For implementing the thin client GIS computing environment, we were using NGII's(National Geographic Information Institute's) DXF map, representing the map by SVG(Scalable Vector Graphics) recommended by OGC(OpenGis Consortium), and adapting standard XML web service to provide the thin client GIS service on PDA by applying the location information of the user in realtime with GPS on mobile environment.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.6
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• pp.549-559
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• 2008

This study verified the limitations of commercial GPS data processing software and the applicability on precise positioning through comparing the processing results between Bernese and TGO under various conditions. To achieve the goal, we selected three nationwide station data and two smaller local data to constitute networks. By using Bernese and TGO, those networks are processed through the baseline analysis and the network adjustment. The comparative analysis was carried out, in terms of software, baseline length and network scale, observation duration, and number of fixed points. In the comparison between softwares, the scientific software was excellent in accuracy. It was confirmed that, as GPS-related technology is developed, the performance of the receiver was enhanced. And, in parallel with this, even the functionalities of the commercial software were tremendously enhanced. The difference, however, in result between the scientific and commercial software are still exist even if it is not big. Therefore, this study confirms that the scientific software should be used when the most precise position is necessary to be computed, especially if baseline vectors are big.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.6
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• pp.717-723
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• 2020

Determination of local tie vectors between the space geodetic techniques such as VLBI (Very Long Baseline Interferometer), SLR (Satellite Laser Ranging), DORIS (Doppler Orbit determination and Radiopositioning Integrated on Satellite), GNSS (Global Navigation Satellite System) is essential for combination of ITRF (International Terrestrial Reference Frame). Therefore, it is required to compute IVP (Invariant Point) position of each space geodetic technique with high accuracy. In this study, we have computed Sejong VLBI IVP position by using updated mathematical model for adjustment computation so that the improvement on efficiency and reliability in computation are obtained. The measurements used for this study are the coordinates of reflective targets on the VLBI antenna and their accuracies are set to 1.5 mm for each component. The results show that the position of VLBI IVP together with its standard deviation is successfully estimated when they are compared with those of the results from previous study. However, it is notable that additional terrestrial surveying should be performed so that realistic measurement errors are incorporated in the adjustment computation process.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.1
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• pp.13-20
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• 2021

A series of numerical experiments with measurements observed at continuously operating reference stations (CORS) of the international GNSS services (IGS) and the national geographical information institute of Korea (NGII) have been intensively carried out to evaluate the quality of pseudo-ranges and carrier-phases of GPS L2C signal obtained by various receiver types, benign and harsh operational environment. In this analysis, some quality measures, such as signal-to-noise ratio (SNR), the magnitude of multipath, and the number of cycle slips, the pseudo-range and carrier phase obtaining rate were computed and compared. The SNR analysis revealed an impressive result that the trend in the SNR of C/A and the L2C comparably depends upon type of receivers. The result of multipath analysis also showed clearly different tendency depending on the receiver types. The reason for this inconsistent tendency was seemed to be that the different multipath mitigation algorithm built-in each receiver. The number of L2C cycle slip was less than P2(Y), and L2C measurements obtaining rate was higher than that of P2(Y) in three receiver types. In the harsh observational environment, L2C quality was not only superior to P2(Y) in all aspects such as SNR, multipath magnitude, the number of cycle slips, and measurement obtaining rate, but also it could maintain a level of quality equivalent to C/A. According to the results of this analysis, it's expected that improved positioning performance like accuracy and continuity can be got through the use of L2C instead of existing P2(Y).

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.6
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• pp.689-696
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• 2020

It is known through prior research that the crust of the Korean Peninsula moves southeast at an annual average of 3 cm/year. The 2011 Great East Japan Earthquake caused a great change in the crust of the Korean Peninsula. Since then, the frequency of earthquakes has increased on the Korean Peninsula. Therefore, by using NGII and IGS GNSS observation data of the recent 15 years, to analyze the trends of changes in the deformation of the Korean Peninsula before and after the outbreak of the Great East Japan Earthquake. Data processing utilized Bernese Software V5.2, a widely used scientific and technical software around the world. As a result, the global movement of the Korean peninsula differed by about 4mm and the direction of movement by about 10° compared to before the Great East Japan Earthquake. As for the internal distortion of the Korean Peninsula, the East-West expansion of the Korean peninsula's crust was observed during the Great East Japan Earthquake, but it is believed that it has not fully returned to the level before the Great East Japan Earthquake.