• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.4
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• pp.116-125
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• 2020

Incalculable damage will be incurred if the national infrastructure that provides services using GNSS signals is affected by jamming signals. To prevent this, a nationwide GNSS jamming monitoring network is necessary to detect the occurrence of a jamming signal, determine the type, and properly localize the jammer position. In this paper, 2-D images for live GNSS signals were generated to verify the environment of the jamming signals through the presence and type of GNSS jamming signals at K-City, which are the test beds for self-driving vehicles, and Incheon International Airport. The analysis was also conducted to detect the occurrence of the jamming signals, determine the type, and measure the jamming signal strength. As a result, a CWI type of jamming signal was detected in L2 band at K-City and in L5 band at Incheon International Airport.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.4
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• pp.245-258
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• 2015

This study aimed to conduct the standardization of various specifications for determining the proper construction and operation of domestic CORS (Continuously Operating Reference Station). To achieve the plan, the standardization was proposed for various compositions of CORS, such as the data quality, structure, and equipment. Also, we have studied the method for empirically determining the reference values of QC (Quality Check) of CORS data. Those large amounts of samples for each QC index values were built to approach in empirical and statistical methods. In fact, those general and recommended reference values were determined from analyzing the sample distributions, using the empirical and statistical approaches. The result is expected to be utilized for a variety of research fields for standardization, accurate data acquisitions and service operations for the domestic CORS

• Journal of the Korean Society for Aviation and Aeronautics
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• v.18 no.1
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• pp.11-18
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• 2010

GNSS(Global Navigation Satellite System) Ground Station performs GNSS signal acquisition and processing. This system generates error correction information and distributes them to GNSS users. GNSS Ground Station consists of sensor station which contains receiver and meteorological sensor, monitoring and control subsystem which monitors and controls sensor station, control center which generates error correction information, and uplink station which transmits correction information to navigation satellites. Monitoring and control subsystem acquires and processes navigation data from sensor station. The processed data is transmitted to GNSS control center. Monitoring and control subsystem consists of data acquisition module, data formatting and archiving module, data error correction module, navigation determination module, independent quality monitoring module, and system maintenance and management module. The independent quality monitoring module inspects navigation signal, data, and measurement. This paper introduces independent quality monitoring and performs the analysis using measurement data.

• Journal of information and communication convergence engineering
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• v.6 no.3
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• pp.239-244
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• 2008

Cargo tracking issue on train transportation is challenging area because of long distance haulage, theft, terror attack and customer service. This paper aims at evaluating various cargo tracking systems in terms of cost and technology. The contents of this paper consist of the research trend of cargo tracking system in the railroad transportation and reviewing of technical alternatives in cost and service side. GNSS and RFID are reviewed as location tracking technology, Internet and Satellite technology like INMASAT and Low Earth Orbit are also reviewed as communication infrastructure. This paper selects cost and service factors in two alternatives of GNSS-Satellite and RFID-Internet, among GNSS-Internet, GNSS, Satellite, RFID-Internet, RFID-Satellite and evaluate each alternative in terms of cost and service. In a result, in terms of cost, RFID-Internet type is superior to GNSS-Satellite type, but in service GNSS-Satellite type is preferred to RFID-Internet in point of area coverage and service coverage.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.1
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• pp.133-139
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• 2010

GNSS receiver which uses the weak satellite signal is very vulnerable to the intentional jamming or non-intentional electromagnetic interference. It is a very simple method among the use method of GNSS receiver to vary tracking loop bandwidth of satellite signal appropriately as the jamming signal level. In this paper, this anti-jamming performance is experimented and analyzed in the laboratory and the anechoic chamber by the GNSS simulator to generate the satellite signal and the jamming signal generator to generate the jamming signal.

• Journal of Positioning, Navigation, and Timing
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• v.7 no.4
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• pp.205-215
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• 2018

The recent emergence of new Global Navigation Satellite Systems (GNSS) has resulted in a gradual improvement in the performance of positioning services. This paper verifies the degree of improvement in positioning performance of Assisted-GNSS (A-GNSS) receivers using assistance information compared to standalone-GNSS receivers that do not use assistance information in various urban environments in Korea. For this purpose, field tests are performed in various urban and indoor environments in Korea. The assistance information is provided by u-blox's AssistNow Online and low-cost commercial receivers are used for mobile station receivers. Through experiments, the Time to First Fix (TTFF), acquisition sensitivity, and position accuracy performance improvement are analyzed. The results of the experiments show that using assistance data improved the performance in all experiment locations, and, in particular, a significant performance improvement in terms of TTFF.

• Journal of Positioning, Navigation, and Timing
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• v.13 no.2
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• pp.137-147
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• 2024

This paper presents a novel Long Short-Term Memory (LSTM) network architecture for the integration of an Inertial Measurement Unit (IMU) and Global Navigation Satellite Systems (GNSS). The proposed algorithm consists of two independent LSTM networks and the LSTM networks are trained to predict attitudes and velocities from the sequence of IMU measurements and mechanization solutions. In this paper, three GNSS receivers are used to provide Real Time Kinematic (RTK) GNSS attitude and position information of a vehicle, and the information is used as a target output while training the network. The performance of the proposed method was evaluated with both experimental and simulation data using a lowcost IMU and three RTK-GNSS receivers. The test results showed that the proposed LSTM network could improve positioning accuracy by more than 90% compared to the position solutions obtained using a conventional Kalman filter based IMU/GNSS integration for more than 30 seconds of GNSS outages.

• Journal of Cadastre & Land InformatiX
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• v.50 no.1
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• pp.107-123
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• 2020

With stabilization of the recent multi-GNSS infrastructure, and as multi-GNSS has been proven to be effective in improving the accuracy of the positioning performance in various industrial sectors. In this study, in view that SF(Single frequency) GNSS receivers are widely used due to the low costs, evaluate effectiveness of SF Real Time Point Positioning(SF-RT-PP) based on four multi-GNSS surveying methods with RTCM-SSR correction streams in static and kinematic modes, and also derive response challenges. Results of applying SSR correction streams, CNES presented good results compared to other SSR streams in 2D coordinate. Looking at the results of the SF-RT-PP surveying using SF signals from multi-GNSS, were able to identify the common cause of large deviations in the altitude components, as well as confirm the importance of signal bias correction according to combinations of different types of satellite signals and ionospheric delay compensation algorithm using undifferenced and uncombined observations. In addition, confirmed that the improvement of the infrastructure of Multi-GNSS allows SF-RT-SPP surveying with only one of the four GNSS satellites. In particular, in the case of code-based SF-RT-SPP measurements using SF signals from GPS satellites only, the difference in the application effect between broadcast ephemeris and SSR correction for satellite orbits/clocks was small, but in the case of ionospheric delay compensation, the use of SBAS correction information provided more than twice the accuracy compared to result of the Klobuchar model. With GPS and GLONASS, both the BDS and GALILEO constellations will be fully deployed in the end of 2020, and the greater benefits from the multi-GNSS integration can be expected. Specially, If RT-ionospheric correction services reflecting regional characteristics and SSR correction information reflecting atmospheric characteristics are carried out in real-time, expected that the utilization of SF-RT-PPP survey technology by multi-GNSS and various demands will be created in various industrial sectors.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.10
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• pp.1483-1488
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• 2012

This paper analyzed the precision and accuracy of the altitude-aided GNSS using the altitude information from digital map. The precision of altitude-aided GNSS is analysed using the theoretically derived DOP. It is confirmed that the precision of altitude-aided GNSS is superior to the general 3D positioning method. It is also shown that the DOP of altitude-aided GNSS is independent of altitude bias error while the accuracy was influenced by the altitude bias error. Furthermore, it is shown that, since the altitude bias error influenced differently to each pseudorange measurement, the effect of the altitude bias error is more serious than clock bias error which does not influence position error at all. The results are evaluated by the simulation using the commercial RF simulator and GPS receiver. It confirmed that altitude-aided GNSS could improve not only precision but also accuracy if the altitude bias error are small. These results are expected to be easily applied for the performance improvement to the land and maritime applications.

• Journal of Positioning, Navigation, and Timing
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• v.4 no.1
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• pp.9-16
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• 2015

The applications of Global Navigation Satellite System (GNSS) receivers are becoming wider in various commercial and military systems including even small weapon systems such as artillery shells. The precision-guided munitions such as Small Diameter Bomb (SDB) of United States can be used for pinpoint strike by acquiring and tracking GNSS signals in high mobility situation. In this paper, a small GNSS receiver with embedded interference suppression capability working under high dynamic stress is developed which is applicable to the various weapon systems and can be used in other several harsh environments. It applies a kind of matched filter and multiple correlator schemes for fast signal acquisition and tracking of even weak signals and frequency domain signal processing method to eliminate the narrowband interference. To evaluate the performance of the developed GNSS receiver, the test scenario of high mobility and interference environment with the GNSS simulator and signal generator is devised. Then, the signal acquisition time, navigation accuracy, sensitivity, and interference suppression performances under high dynamic operation are evaluated. And the comparison test with the commercial GNSS receiver which has high sensitivity is made under the same test condition.