• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.9
• /
• pp.66-72
• /
• 2005

As one of the methods that determine position using GPS carrier phase without the resolution of integer ambiguity, the characteristics of the time difference is analyzed in this paper. When determining position by the needed accuracy, the difference time gap becomes an important factor. It is said that accuracy is improved as the difference time gap is getting large, and finally the centimeter level accuracy is achieved after a certain difference time gap. In this paper, the characteristics of the time difference is analyzed using real data and a new parameter is proposed to predict the resulting position accuracy. The difference time gap when position error is converged to the centimeter level is estimated with the proposed parameter.

• Journal of Advanced Marine Engineering and Technology
• /
• v.35 no.5
• /
• pp.682-689
• /
• 2011

Recently, there are frequent disasters by Swell-like Wave in the coastal area, Korea peninsula. This phenomenon (Swell-like Wave) has long period above 10 seconds compared with wind wave. To prevent these disasters by the long-period wave in advance, it's necessary to observe it in real time. But existing instruments for wave observation can not observe long-period wave because they mainly are aimed to measure the short-period wind wave. Therefore, in this research it is tried to develop the GPS based Long Period Wave Observation System which real time operation can be realzied in the sea.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.20 no.2
• /
• pp.183-190
• /
• 2002

This study is about the extraction of highway's superelevation using real time kinematic surveying among of GPS surveying methods which is economic method to construct data base in the side of highway maintain management. Using the developed vehicle, center line and shoulder of highway are measured and enough precision is obtained after analyzing the result. The result is show that 1.3 cm to 2.0 cm error in the clothed and about 0.8 cm to 1.2 cm error in the circular curve. Those errors are proved error to lane making during construction. This study is expected to become efficient method for extraction of highway alignment elements in the Mobile Mapping System.

• Journal of information and communication convergence engineering
• /
• v.8 no.1
• /
• pp.83-88
• /
• 2010

Recently car navigation systems which have been widely spread and evolved. The systems use various information and techniques such as real time traffic information and augmented reality technique. In order to provide a shortest path with good flow, real-time traffic information provided by DMB is required. Augmented reality technique is also introduced to give a reality to driver by displaying real images captured by camera during driving. However, these operate well when the system receives GPS data normally. Exact information about the positions of vehicles is a base that supports the above function with realities. This paper proposes a model for acquiring exact position of vehicles. When the GPS does not operate normally, the proposed model uses various data which are generated by integrated vehicle networks.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2004.04a
• /
• pp.113-117
• /
• 2004

Such social structures as bridges, buildings, dams and towers have been transformed by their own load or fundamental ground. They have been behaved by other external causes. These regular or irregular behaviors threaten to do their users safety. Therefore, to monitor the load of the structures or reaction shown by them could help to verify their behaviors. RTK GPS allows the use of a static base station and remote rover unit to allow for data collection within several seconds and in real time. It is useful for monitoring the behaviors of massive structures like bridges. In this Study, Among GPS methods, we used RTK GPS to analyze the precision of monitoring and then on the basis of it, we developed a monitoring system using RTK GPS when measured the behavior of main tower of a suspension bridge by using RTK GPS. Comparing a deviation between observation values, X axis was 1mm, Y axis was 1mm and Z axis 2.2mm. It turned out that it was possible to monitor and measure structures by RTK GPS.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2004.04a
• /
• pp.139-144
• /
• 2004

This study aims to analyze the accuracy of rover speed change in route surveying using RTK-GPS. Route surveying methods using GPS contain Static, DGPS, and RTK-GPS. Much research of navigation system, positioning of vehicles by DGPS, and accuracy analysis by GPS surveying have already been done. From this study, it is firstly found that DGPS is suitable for car navigation and sea navigation with an error of meter scale but not good for detailed construction, designing maps and updating GIS databases. Secondly, RTK-GPS can be used for managing gas pipes, water supply and drain pipes and fiber-optic cable that are needed to be controlled in a real time basis. Thirdly, since the accuracies of route surveying by RTK-GPS and DGPS are not correctly matched with the change of rover speed, the choice of route surveying method from those two should follow the need of accuracy fidelity Further study should focus on Cycle Slip problem and coordinate change problem in tunnel and mountainous areas.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.41 no.6
• /
• pp.187-193
• /
• 2004

In this paper, we proposed the GPS position data correction method for autonomous land navigation using vanishing point property and a monocular vision system. Simulations are carried out over driving distances of approximately 60 km on the basis of realistic road data. On a straight road, the proposed method reduces GPS position error by at least 63% within 0.5 m. However, the average accuracy of the method is not presented, because it is difficult to estimate it on other than a straight road in variable conditions.

• International Journal of Aeronautical and Space Sciences
• /
• v.2 no.1
• /
• pp.55-66
• /
• 2001

The Global Positioning System(GPS) and the Strapdown Inertial Navigation System(SDINS) techniques have been widely utilized in many applications. However each system has its own weak point when used in a stand-alone mode. SDINS suffers from fast error accumulation dependent on an operating time while GPS has problem of cycle slips and just provides low update rate. The best solution is to integrate the GPS and SDINS system and its integration allows compensation for each shortcomings. This paper, first, is to define and derive error equations of integrated SDINS/GPS system before it will be applied on a real hardware system with gyro, accelerometer and GPS receiver. Second, the accuracy, availability and performance of this mechanization are verified on the simulation study.

• Journal of Positioning, Navigation, and Timing
• /
• v.3 no.3
• /
• pp.123-129
• /
• 2014

The real-time kinematic (RTK) is one of precise positioning methods using Global Positioning System (GPS) data. In the long baseline GPS RTK, the ionospheric and tropospheric delays are critical factors for the positioning accuracy. In this paper we present RTK algorithms for long baselines more than 100 km with estimating tropospheric delays. The state vector is estimated by the extended Kalman filter. We show the experimental results of GPS RTK for various baselines (162.10, 393.37, 582.29, and 1283.57 km) by using the Korea Astronomy and Space Science Institute GPS data and one International GNSS Service (IGS) reference station located in Japan. As a result, we present that long baseline GPS RTK can provide the accurate positioning for users less than few centimeters.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.16 no.1
• /
• pp.41-50
• /
• 1998

The object positional data in the form of digital imagery is processed and stored and is updated easily. The GPS, positioning system using satellites, is acquired its utilities in many parts because it is very easy to get the three dimensional coordinates using GPS around the world. For the effective acquisition of positional data to-ward objects in space, the automation of digital photogrammetry must be done and data acquisition and processing should be performed in real-time. In this study, the program is developed for automatic process of digital photogrammetry and the VAN that has CCD cameras and GPS receivers onboard is built for mobile positioning system. Also, the three dimensional positioning toward 20 objects which are vertical to the ground is done using left and right imagery of CCD cameras and GPS. For a base research in real-time photogrammetry, the three dimensional positioning is performed using continuous imagery and GPS and the three dimensional positioning accuracy is analyzed.