• Journal of Astronomy and Space Sciences
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• v.26 no.2
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• pp.229-236
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• 2009

KOorea Multi-purpose SATellite(KOMPSAT)-5 will be launched at 550km altitude in 2010. Accurate satellite position(20 cm) and velocity(0.03 cm/s) are required to treat highly precise Synthetic Aperture Radar(SAR) image processing. Ionosphere delay was eliminated using dual frequency GPS data and double differenced GPS measurement removed common clock errors of both GPS satellites and receiver. SAC-C carrier phase data with 0.1 Hz sampling rate was used to achieve precise orbit determination(POD) with ETRI GNSS Precise Orbit Determination(EGPOD) software, which was developed by ETRI. Dynamic model approach was used and satellite's position, velocity, and the coefficients of solar radiation pressure and drag were adjusted once per arc using Batch Least Square Estimator(BLSE) filter. Empirical accelerations for sinusoidal radial, along-track, and cross track terms were also estimated once per revolution for unmodeled dynamics. Additionally piece-wise constant acceleration for cross-track direction was estimated once per arc. The performance of POD was validated by comparing with JPL's Precise Orbit Ephemeris(POE).

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.6
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• pp.733-739
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• 2009

Recently it is being increased rapidly to install magnetic marker and RFID tag on the underground utility lines before backfilling to ensure effective it's management. However, due to changes an attitude and damages of sensors. By pressure and vibration during soil compacting, detecting rate is significantly reduced as well as it allows to use only one line of various pipes since it has an unique frequency. Also it is required too long time to reach to target point with an non-accurate navigational GPS receiver and hard to update existing data base with a manual input of new data in the field. To improve these problems, the researcher developed the field management system that apply with ball typed self-levelling marker which is free from the changes of attitude for sensors during compaction as well as has various radio frequency applicable to many kind of pipes and ensure fast positioning to target point using an incorporated system with PDA based DGPS receiver which allows loading a field GIS software and RFID detector. Further, it provides with viewing all of RFID data on the DGPS receiver screen directly and also input new data to existing data base in the field automatically.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.4
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• pp.251-261
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• 2003

To measure the GPS position accuracy and its distribution according to the length of the baseline, 30 minutes to 24 hours observations at the fixed location were conducted with two GPS receivers (Ll, 12 channels) on May 29 to June 2, 2002. The GPS data received at the reference station, the rover station and the ordinary times GPS observation station operated by the National Geography Institute in Korea were processed in kinematic and static post-processing methods with a post -processing software. The results obtained are summarized as follows: 1. The number of the satellite that could be observed continuously more than six hours was 16 and most of these satellites were positioned at east-west direction on May 31, 2002. The number of the satellite observed and the geometric dilution of precision (GDOP) determined by the average of every 10 minute for the day were 8 and 3.89, respectively. 2. Both the average GPS positions before and after post-processing were shifted (standalone: 1.17 m, post -processing: 0.43m) to the south and west. The twice distance root mean square (2drms) measured with standalone was 6.65m. The 2drms could be reduced to 33.8% (standard deviation 0=17.2) and 5.3% (0=2.2) of standalone by the kinematic and the static post-processing methods, respectively. 3. The relationship between the length of the baseline x (km) and the 2drms y (m) obtained by the static post-processing method was y=0.00l6x+0.006 $(R^2=0.87)$. In the case of the positioning with the static post-processing method using the GPS receiver, it was found that a positioning within 20cm 2drms was possible when the length of the baseline was less than 100km and the receiving time of the GPS is more than 30 minutes.

• Journal of Korean Society for Geospatial Information Science
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• v.16 no.4
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• pp.49-57
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• 2008

The cemetery areas which are occupied more than 1.0 percent of whole land of Korea have widened gradually but the reconnaissance is not being conducted for the cemetery investigation due to deficiencies for budget and manpower of the government. The aim of this study is to find a method to establish the lower cost GIS-based cemetery management system by using hand-held DGPS receiver and Mobile GIS software system for easy cemetery management. The results were evaluated and compared to the RTK GPS method. Since the Cemetery Management System shows every tomb's position on the high resolution satellite imagery with a cadastral data, the map helps to find the interesting places easily. Therefore the system data can be used for various purposes such as planning for land development, dealing with real estate as well as cemetery management.

• Journal of Positioning, Navigation, and Timing
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• v.13 no.1
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• pp.75-83
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• 2024

In order to reduce the time and cost of developing a navigation system, a performance evaluation platform can be used. A User Interface (UI) is required to effectively evaluate the performance, which sets parameters and gives navigation sensor signals and data display, and also displays navigation results. In this paper, a LabVIEW-based UI design method for multi-integrated navigation systems is proposed and implementation results are presented. The UI consists of a signal and data generation part and a signal and data processing part. The signal and data generation part sets parameters for the signal and data generation and displays the navigation sensor signal and data generation results. The signal and data processing part sets parameters for the signal and data processing and displays the navigation results. The signal and data generation part and signal and data processing part are designed to satisfy the requirements of the UI for a performance evaluation of the navigation system. In order to show the usefulness of the proposed UI design method, parameters of the signal and data generation and the signal and data processing are set through the LabVIEW-based UI, and the Global Positioning System (GPS) signal and inertial measurement unit data generation results and the navigation results of a GPS Software Defined Receiver (SDR) and inertial navigation system are confirmed. The implementation results show that the proposed UI design method helps users conduct an effective performance evaluation of navigation systems.

• Journal of Positioning, Navigation, and Timing
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• v.3 no.1
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• pp.25-30
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• 2014

Differential Global Positioning System-Correction Projection (DGPS-CP) algorithm, which has been suggested as a method of correcting pre-calculated position error by projecting range-domain correction to positional domain, is a method to improve the accuracy performance of a low price GPS receiver to 1 to 3 m, which is equivalent to that of DGPS, just by using a software program without changing the hardware. However, when DGPS-CP algorithm is actually realized, the error is not completely eliminated in a case where a reference station does not provide correction of some satellites among the visible satellites used in user positioning. In this study, the problem of decreased performance due to the difference in visible satellites between a user and a reference station was solved by applying the Multifunctional Transport Satellites (MTSAT) based Augmentation System (MASA) correction to DGPS-CP, instead of local DGPS correction, by using the Satellite Based Augmentation System (SBAS) operated in Japan. The experimental results showed that the accuracy was improved by 25 cm in the horizontal root mean square (RMS) and by 20 cm in the vertical RMS in comparison to that of the conventional DGPS-CP.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.2
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• pp.75-82
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• 2016

Visible light communication (VLC) using LED lamps is suitable for implementing an indoor positioning system in an indoor environment where the global positioning system (GPS) signal does not reach. In this paper, we present an indoor positioning system for mobile robots using a VLC beacon and fuzzy rules. This system consists of an autonomous mobile robot, VLC modules, and device application software. Fuzzy rules are applied to plan the global and local paths along which the mobile robot navigates indoors. The VLC transmitter modules are attached to the wall or the ceiling as beacons to transmit their own location information. The variable pulse position modulation (VPPM) algorithm is used to transmit data, which is a new modulation scheme for VLC providing a dimming control mechanism for flicker-free optical communication. The mobile robot has a receiver module to receive the location information while performing its mission in the environment where VLC transmitters are deployed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2113-2118
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• 2016

The precise detection of electric leakage point of underground power cable is very important to reduce cost and time of maintenance and prevent electric shock accident through expedite repair of electric leakage point. This paper proposes a electric leakage point detection system underground power cable using of half-period modulated transmission waveform and earth electric potential measurement. The developed system is composed of transmitter to generate the wanted pulse waveform, receiver to measure and display earth electric potential by the transmitted pulse in electric leakage point and PC Software program to display of GPS coordinate on detection cable line. The performance of the electric leakage point detection system was tested in the constructed underground cable leakage detection test bed. The test results on signal generation voltage precision of signal transmitter, mean detection earth voltage, mean detection leakage current and electric leakage point detection error showed the developed system can be used in electric leakage point detection underground power cable.

• Journal of the Korea Society of Computer and Information
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• v.24 no.8
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• pp.29-35
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• 2019

This paper proposes a UAV equipped with an automatic control system for educational purposes such as navigation flight or autonomous flight. The proposed UAV is capable of automatic navigation flight and it is possible to control more precisely and delicately than existing UAV which is directly controlled. And it has the advantage that it is possible to fly in a place out of sight. In addition, the user may arbitrarily change the route or route information to use it as an educational purpose for achieving the special purpose. It also allows you to check flight status by shooting a video during flight. For this purpose, it is designed to check the image in real time using 5.8GHz video transmitter and receiver. The flight information is recorded separately and used as data to judge the normal flight after the flight. The result of the paper can be flighted along the coordinates specified using GPS information. Since it can receive real-time video, it is expected to be used for various education purposes such as reconnaissance of polluted area, achievement of special purpose, and so on.

• Journal of Biosystems Engineering
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• v.37 no.4
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• pp.225-232
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• 2012

Purpose: Accurate monitoring of information from various agricultural vehicles is one of the most important factors for appropriate management strategy of field operations. While there has been a number of study and design on applications of sensors and actuators for data acquisition and control system in tractor, incompatibility between various customized hardware and software has become a major obstacle to the universal deployment in real field operation. International standard for implementation of electronic control unit (ECU) in agricultural vehicles has becoming a mandatory requirement for inter-operation compatibility in the international trade of agricultural vehicle industries. The ISO 11783 standard is basically based upon well known communication technology designated using the controller area network (CAN) bus. While CAN bus could provide 1.0 Mbps of communication speed, the standard only recommended 250 kbps. Methods: This study presents the implementation and evaluation of ISO 11783 for tractor electronic control units (TECU)with a higher transmission rate from multiple ECU than 250 kbps. Throughput and loss rate of the developed prototype were calculated across manipulated bus load for laboratory experimental tests, and the maximum requirement of transmission rate by ISO 11873 was satisfied with lower than 60% of bus load. Results: Field tests with a TECU implemented to process messages from global positioning system (GPS) receiver resulted that the root mean square error of position information was lower than 4 m with 0.5 m/s as a travelling speed. Conclusions: Results of this study represent the utilization of the international standard ISO 11783 to providepractical developments in terms with the inter-operability of TECU.