• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.5
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• pp.407-412
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• 2014

Concerns and demands for the Location Based Services (LBS) using Global Positioning System (GPS) and Wi-Fi are largely increased in the world in the present. In some experimental results, it was noted that many errors are frequently occurred when the distances between an anchor node and a mobile node acre measured in indoor localization environment of Wireless Personal Area Network (WPAN). In this paper, localization compensation algorithm based on maximum measurement value ($LCA_{MMV}$) for moving objects in WPAN is proposed, and the performance of the algorithm is analyzed by experiments on three scenarios for movement of mobile nodes. From the experiments, it was confirmed that the average localization accuracy of suggested algorithm was more increased than Symmetric Double-Sided Two-Way Ranging (SDS-TWR) and triangulation as average 40.9cm, 77.6cm and 6.3cm, respectively on scenario 1-3.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.3
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• pp.127-137
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• 2018

Recently, UAVs and Drones have been used for various applications. In particular, in the field of surveying, there are studies on the technology for monitoring the terrain based on the high resolution image data obtained by using the UAV-equipped digital camera or various sensors, or for generating high resolution orthoimage, DSM, and DEM. In this study, we analyzed the accuracy of GCP(Ground control point) matching using UAV and VRS-GPS. First, we used VRS-GPS to pre-empt the ground reference point, and then imaged at a base altitude of 150m using UAV. To obtain DSM and orthographic images of 646 images, RMSE was analyzed using pix4d mapper version As a result, even if the number of GCP matches is more than five, the error range of the national basic map(scale : 1/5,000) production work regulations is observed, and it is judged that the digital map revision and gauging work can be utilized sufficiently.

• Spatial Information Research
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• v.23 no.3
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• pp.91-100
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• 2015

We developed a micro UAV based rapid mapping system that provides geospatial information of target areas in a rapid and automatic way. Users can operate the system easily although they are inexperienced in UAV operation and photogrammetric processes. For the aerial data acquisition, we constructed a micro UAV system mounted with a digital camera, a GPS/IMU, and a control board for the sensor integration and synchronization. We also developed a flight planning software and data processing software for the generation of geo-spatial information. The processing software operates automatically with a high speed to perform data quality control, image matching, georeferencing, and orthoimage generation. With the system, we have generated individual ortho-images within 30 minutes from 57 images of 3cm resolution acquired from a target area of $400m{\times}300m$.

• 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.

• Spatial Information Research
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• v.16 no.3
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• pp.317-330
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• 2008

In this paper, the acquisition of digital imagery and the orthoimage generation were performed to set up working process. And another purpose of this thesis is to evaluate the accuracy of orthoimage by overlapping digital topographic map and digital cadastral map on it. The digital topographic map and digital cadastral map were superimposed on the orthoimage to check the accuracy as another approach of evaluation. The RMSE is ${\pm}0.364m$ in X direction and ${\pm}0.413m$ in Y direction with digital topographical maps(1/5,000). And the RMSE is ${\pm}1.283m$ in X direction and ${\pm}1.085m$ in Y direction with digital cadastral map. It is necessary for the application of a newly developed digital aerial camera to make an exact synchronization between GPS/IMU data and image data, use a technology for setting a standard image resolution and the number of ground control points.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.1
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• pp.47-52
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• 2008

The visual implementation of 3-dimensional national environment is focused by the requirement and importance in the fields such as, urban planing, telecommunication facility deployment plan, railway construction, construction engineering, spatial city development, safety and disaster prevention engineering. The currently used DEM system based on the 2-D digital maps and contour lines has limitation in implementation in reproducing the 3-D spatial city. Currently, the LiDAR data which combines the laser and GPS skill has been introduced to obtain high resolution accuracy in the altitude measurement in the advanced country. In this paper, we first introduce the LiDAR based researches in advanced foreign countries, then we propose the data generation scheme and an solution algorithm for the optimal management of our 3-D spatial u-City construction. For this purpose, LiDAR based height data transformed to DEM, and the realtime unification of the vector via digital image mapping and raster via exactness evaluation is transformed to make it possible to trace the model of generated 3-dimensional model with long distance for 3D u-city model generation.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.4
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• pp.67-74
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• 2015

GNSS/Leveling technology makes it possible to get geoidal height geometrically using GNSS and Leveling technology. GNSS/Geoid technology refers to a technology for obtaining orthometric height by subtracting geoidal height achieved by Geoid technology from ellipsoidal height achieved by GNSS technology. The purpose of this study is to verify the accuracy of the ellipsoidal height determination in order to verify the accuracy of the orthometric height determination by the GNSS/Geoid technology. For the study, a test bed was selected in Kyungnam province and GNSS Static surveying was accomplished in the test bed and then the GNSS data was processed in accordance with various analysis conditions. So, it was verified the accuracy of the ellipsoidal heights determination in accordance with the surveying conditions under the GNSS Static surveying. According to the research results, to ensure the 3cm goal accuracy of the ellipsoidal height determination, it should be surveyed by four fixed points on the survey area periphery and more than two hours of the GNSS occupation time, And also, it was found that should be limited to a baseline distance of 20km under the GNSS Static surveying.

• Journal of the Korean Association of Geographic Information Studies
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• v.7 no.4
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• pp.15-23
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• 2004

In order to utilize remote sensed images effectively, it is necessary to correct geometric distortion. Geometric correction is a critical step to remove geometric distortions in satellite images. For geometric correction, Ground Control Points (GCPs) have to be chosen carefully to guarantee the quality of geocoded satellite images, digital maps, GPS surveying or other data. Traditional approach to geometric correction used GCPs requires substantial human operations. Also that is necessary much time and manpower. In this paper, we presented an on-line automatic geometric correction by constructing GCP Chip database. The Proposed on-line automatic geometric correction system is consists of four part. Input image, control the GCP Chip, revision of selected GCP, and output setting part. In conclusion, developed system reduced the processing time and energy for tedious manual geometric correction and promoted usage of Landsat imagery.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.71-78
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• 2010

The road safety depend on many road factors like vertical alignment, horizontal alignment and road cross section angle. These data are hardly to get with drawings, and the real data are differ from drawings because of road pavement overlay, etc. To get these data, so many time and cost are needed, moreover it is dangerous work in heavy traffic road. In this study we obtained the road safety data with RoSSAV(Road Safety Survey & Analysis Vehicle) of Korea Institute of Construction Technology in accordance with traffic flow, and make analysis of road safety with the vertical alignment, horizontal alignment and road cross section angle data. We derived the safety improvement method in Young-dong accident prone spot and described detail method in this paper.

• Korean Journal of Remote Sensing
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• v.24 no.2
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• pp.133-140
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• 2008

In this paper, we analyzed the accuracy of orbit modeling with various control point configurations and adjustment unknown parameter sets. We used 152 GCP points acquired from GPS surveying, which were distributed from Choon-chun to Nha-ju along 420km in distance. For orbit modeling, seven adjustment parameter sets were chosen to include parameters for satellite position, velocity and attitude angles at different degree of freedom. Firstly we determined the location of model point in seven configurations. Secondly we estimated model parameters for each parameter set and for each GCP configurations. Finally we applied the model to reference check points and analyzed its accuracy. We were able to find the unknown parameter set that produce best orbit modeling performance regardless of the configuration of model points.