• Journal of the Korean Society of Marine Environment & Safety
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• v.10 no.2 s.21
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• pp.61-67
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• 2004

The development motive and maintenance of navigation system were military strategy purpose since middle of 20th century. During cold war period between the United States and the Soviet since the Second World War, advanced navigation system that two countries are responded individually have done development competitively. These systems are exhibited on general except military purpose gradually and are taking charge of point role in economy transport activity such as transportation of logistics between the country. Navigation system can divide into ground system and satellite system. Representative system of ground system is Loran-C(Long Range Navigation), and representative system of satellite system is GPS(Global Position System). Loran-C system is a system that use much in all the world country sea and ground, but GPS and DGPS that present is a satellite navigation system are used much. According to development of satellite system, examine about actual conditions of Loran-C navigation system and practical use plan in this paper because there is controversy about role of Loran-C navigation device along with Loran-C's operation and user decrease, and discusses for Loran-C's development direction.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.4
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• pp.355-363
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• 2007

The purpose of this study is to maximize the use of framework data by a method for updating road framework data using a economical, rapid, and accurate Vehicle-based kinematic survey to get the latest road data among "transportation framework data" which was built in 2003. We collected data using a Vehicle-based kinematic survey with DGPS (Differential Global Positioning System) in Daejeon and Pyeongtaek city and verified the accuracy of line and point features between surveying and previous results. The result showed that Daejeon city which is located near GPS CORS (Continuously Operating Reference Station)s and receive a signal well had lower errors than 1/5,000 digital base map, and Pyeongtaek city which is located far from the stations and receive a signal badly had errors beyond the limits. The study showed that postprocessing method or Total Station surveying should be used where signals cannot be detected well after analyzing a receiving rate from GPS CORSs, the stations of other organizations should be shared, and further studies are needed.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.2
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• pp.105-116
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• 2004

According to the developing advanced techniques and removal of Selective Availability, much research has been conducted to improve the accuracy of GPS positioning in absolute and relative mode by estimating the nuisance parameters such as atmospheric effect, clock errors and multipath. Especially, the continuous effort of establishing the CORS in many countries and the effort of ICS making effective global networking make more application areas and the necessity of more precise location is being increased. Some of the countries like German, Japan and Swiss already utilized the Virtual Reference System for better location accuracy and services. In this study, the VRS system is investigated in terms of system principle, required H/W and S/W, management and operation, revision of related law, expected application and market etc. and find optimal solution in each aspect for economic and fast set up of the system in this country. The analysis of Korean CORS, communication infra and market estimation is performed for the efficient system establishment. Also. the suggestion on the advertisement and education of the system is also included. It is expected that this study contributes for the establishment of effective and precise nationwide location service so that many SOC areas including navigation, GIS, Telematics, LBS can provides better service for the users.

• Spatial Information Research
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• v.12 no.2
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• pp.181-191
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• 2004

Nowadays, GPS-photogrammetry can be applied to the basemap production, a land register and NGIS. And from now on, as the increase of GPS receiver rate, the study on the interpolation methods considering the exact movement of an aircraft at photoflight and the study on the supplement of GPS defect by INS are required continuously. GPS-Photogrammetry, which are based on the direct measurement of the projection centers and attitude at the moment of camera exposure time through loading the GPS receiver in aircraft. This photogrammetric methods can of for us to acquire the exterior orientation parameters with only minimum ground control points, even the ground control process could be completely skipped. Consequently, we can drastically reduce the time and cost far the mapping process. In this thesis, two test flights were conducted in area to evaluate the performance of accuracy and efficiency through the analysis of results between the two photogrammetric methods, that is, traditional photograrammetry, GPS-Photogrammetry. Test results shows that a large variety of advantages of GPS-Photogrammetry against traditional photogrammetry is to be verified. Especially, the number of ground control points for the exterior orientation could be saved more than 70～80%, and the cost far map production 30～50%, respectively. In addition, it was convinced that the large reduction of control points has not any effect on the block accuracy.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.4
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• pp.409-417
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• 2005

This study is aimed to develop a remote control robot-ship system using wireless communication and DGPS, which it is an automatic system for measuring exact depth and bed topography of reservoir or dam. Robot-ship is equipped with GPS and echosounder, and it is controled remotely using wireless internet. Robot-ship is consist of frame, each module and control board. Control segment is consisted of a processing system for positioning data and remote control system. A wireless communication system is developed which can communicate interactively between robot-ship and control segment, and it is developed in two channel system of RF modem and wireless internet. The robot-ship could be used acquire economically and exactly the water depth and bed topography of reservoirs, dams, rivers and so on.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.6
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• pp.219-230
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• 2017

This paper proposes a vehicle to road tracking algorithm based on vision sensor by using EKF(Extended Kalman Filter). The lateral offset, heading angle, and curvature which are obtained from vehicle to road tracking might be used as inputs to steering controller of LKAS(Lane Keeping Assist System) or for the warning decision logic of LDWS(Lane Departure Warning System). To the end, in this paper, the yaw rate, steering angle, and vehicle speed as well as lane raw points together with considering of vehicle lateral dynamics are utilized to improve the exactness and convergence of the vehicle to road tracking. The proposed algorithm has been tested at a proving ground that consists of straight and curve sections and compared with GPS datum using DGPS-RTK equipment to show the feasibility of the proposed algorithm.

• Spatial Information Research
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• v.15 no.2
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• pp.111-121
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• 2007

The GPS positioning offer 3D position using code and carrier phase measurements, but the user can obtain the precise accuracy positioning using carrier phase in Real Time Kinematic(RTK). The main problem, which RTK have to overcome, is the necessary to have a reference station(RS) when using RTK should be generally no more than 10km on average, which is significantly different from DGPS, where distances to RS can exceed several hundred kilometers. The accuracy of today's RTK is limited by the distance dependent errors from orbit, ionosphere and troposphere as well as station dependent influences like multipath and antenna phase center variations. For these reasons, the author proposes Network based GPS Carrier Phase Differential Positioning using Multiple RS which is detached from user receiver about 30km. An important part of the proposed system is algorithm and software development, named DAUNet. The main process is corrections computation, corrections interpolation and searching for the integer ambiguity. Corrections computation of satellite by satellite and epoch by epoch at each reference station are calculated by a Functional model and Stochastic model based on a linear combination algorithm and corrections interpolation at user receiver are used by area correction parameters. As results, the users can obtain the cm-level positioning.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.4
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• pp.411-418
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• 2004

This paper is the study about a method for determining the azimuth of a baseline by measuring the apparent direction of the Sun. It is simple to realize this method, as it requires, in addition to the apparent direction of the Sun already measured, the observation time and the latitude and the longitude of the survey point. Comparing the azimuths determined by this method and those determined by the PDGPS(Post Processed Differential GPS) on 3 different baselines, the differences(PDGPS - this method) between the azimuths determined by two methods were -13", +45" and +24" respectively. It can be an effective and rapid tool in cases that require the accuracy lower than 1 arc-min.than 1 arc-min.

• Journal of Korean Society for Geospatial Information Science
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• v.11 no.3 s.26
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• pp.23-34
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• 2003

Currently, the efficiency of GPS has been increased in the various precise survey like as the control survey and the navigation etc. Also, it is widely used in the deformation analysis of the structure, the measurement of the marine tides, the measurement of the river level and the topographic monitoring of seabed or riverbed by combined the measurement equipment for depth. In this study, we intend to increase in efficiency of the topographic monitoring of seabed or riverbed by combined with DGPS, RTK GPS and echo sounder. For this study, we defined the error correction of the echo sounder with the experiment of water tank which is considered the characteristic of estuary riverbed and then we developed the s/w for 3-dimensional monitoring of estuary riverbed and applied the s/w to field test and improved the various problems. On analyzing topography of estuary riverbed by combined GPS with echo sounder, the draught error which is yielded to change of length from the water surface by the movement of survey vessel to the end of the transducer was eliminated by geometrical rearrangement and we defined the correction formula $z=BM+SAH-DBR_{(i)}-DRT-ED$. The sounding error about the echo sounder and characteristic of estuary riverbed was found by understanding the relation of average diameter ind residual error and we defined correction formula, $Y=0.00474{\ast}ln(X)-0.0045$ by the regression analysis. and then we verified applicability of correction formula.

• The Journal of Korea Robotics Society
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• v.11 no.3
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• pp.172-182
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• 2016

Lane-level vehicle positioning is an important task for enhancing the accuracy of in-vehicle navigation systems and the safety of autonomous vehicles. GPS (Global Positioning System) and DGPS (Differential GPS) are generally used in navigation service systems, which however only provide an accuracy level up to 2~3 m. In this paper, we propose a 3D vision based lane-level positioning technique which can provides accurate vehicle position. The proposed method determines the current driving lane of a vehicle by tracking the 3D position of traffic signs which stand at the side of the road. Using a stereo camera, the 3D tracking paths of traffic signs are computed and their projections to the 2D road plane are used to determine the distance from the vehicle to the signs. Several experiments are performed to analyze the feasibility of the proposed method in many real roads. According to the experimental results, the proposed method can achieve 90.9% accuracy in lane-level positioning.