• Journal of Advanced Navigation Technology
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• v.24 no.2
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• pp.92-100
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• 2020

Satellite-based argumentation systems (SBAS) is a system that enhances the accuracy, integrity, availability and continuity of GNSS navigation users by using geostationary orbit (GEO) satellites to send correction information and the failures of global navigation satellite system (GNSS) satellites in the form of messages. The correction information provided by SBAS is pseudorange error, satellite orbit error, clock error, and ionospheric delay error at 250 bps. Therefore, A lot of message processing are required for the SBAS navigation. There is a need to reduce SBAS time to first fix (TTFF) for using SBAS navigation in systems with short operating time. In this paper, A-SGNSS operation method was proposed for reducing SBAS TTFF. Also, A-SGNSS TTFF and availability were analyzed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.872-875
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• 2012

Recently, China officially declared to operate its satellite positioning system, Beidou so called Compass. The system is currently having 10 orbiting satellites which regionally cover from Australia to Russia in the north. Moreover, the system will be planed not only to launch 6 navigation satellites in its orbit in 2012 but also to complete the system with 35 satellites in 2020. The China satellite navigation system can affect to the current circumstance of global satellite navigation world in terms of navigation parameters. In this paper, we investigate characteristics of multi-integrated GNSS involving Beidu-Compass system and discuss general issues involving visibility and GDOP.

• 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 Positioning, Navigation, and Timing
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• v.10 no.4
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• pp.353-361
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• 2021

This paper presents the jamming effect on the L5 band of Global Navigation Satellite System (GNSS) by analyzing real data collected via measurement campaigns in Korea region. In fact, the L5 band is one of the dedicated bands for various satellite navigation systems such as Global Positioning System (GPS), Galileo, BeiDou (BDS), and Quasi Zenith Satellite System (QZSS). And this band is also allocated along with various systems used for aeronautical radio navigation systems (ARNS). Among ARNS, the Distance Measuring Equipment (DME) and the Tactical Air Navigation System (TACAN) are systems that transmit and receive strong power pulse signals, which may cause unintentional jamming in the reception of GNSS signals. In this paper, signals in the main lobe of GPS L5, Galileo E5a, BDS B2a, and QZSS L5 are collected in Korean region to confirm whether the jamming effect exists in the band. And then, the pulse blanking technique, which is a simple signal processing technique capable of responding to pulsed jamming, is applied to analyze the jamming effect of DME/TACAN on the L5 band.

• Current Industrial and Technological Trends in Aerospace
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• v.5 no.1
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• pp.65-74
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• 2007

현재 운용중인 전 세계적인 위성항법시스템(GNSS : Global Navigation Satellite System)은 미국의 GPS(Global Positioning System)와 러시아의 GLONASS(Global Navigation Satellite System)가 있다. 전 세계적으로 주로 사용되는 시스템은 GPS이며, GLONASS는 러시아의 경제사정 악화로 인하여 지속적인 위성발사가 이루어지지 못하고 있다. 추가적으로 추진되고 있는 위성항법시스템은 유럽의 갈릴레오(Galileo), 중국의 북두(Beidou), 일본의 JRANS(Japanese Regional Advanced Navigation System) 그리고 2006년 5월에 구축 프로젝트가 승인된 인도의 IRNSS(Indian Regional Navigation Satellite System)가 있다. 보강시스템의 경우, 미국 FAA(Federal Aviation Administration)는 광역오차보정시스템(WAAS)을 Raytheon사와 개발하였으며, 현재 착륙용 근거리오차보정시스템(LAAS)을 Raytheon사 및 Honeywell사와 함께 정부/산업체 공동개발 사업(GIP; Government Industry Partnership)으로 진행 중에 있다. 유럽은 EGNOS(European Geostationary Navigation Overlay Service)를 사용하고 있으며, 일본의 MSAT(MTSAT Satellite Based Augmentation System)와 인도의 GAGAN(GPS and GEO Augmented Navigation)은 추진 중이다. 이 글에서는 위성항법시스템과 위성항법 보강시스템의 현황을 살펴본다.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.1
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• pp.8-14
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• 2013

As GNSS(Global Navigation Satellite System) is used in various filed, many countries establish GNSS system independently. But GNSS system has the limitation of accuracy and stability in stand-alone mode, because this system has error elements which are ionospheric delay, tropospheric delay, orbit ephemeris error, satellite clock error, and etc. For overcome of accuracy limitation, the DGPS(Differential GPS) and RTK(Real-Time Kinematic) systems are proposed. These systems perform relative positioning using the reference and user receivers. ETRI(Electronics and Telecommunications Research Institute) is developing precision navigation system in point of extension of GNSS usage. The precision navigation system is for providing the precision navigation solution to common users. If this technology is developed, GNSS system can be used in the fields which require precision positioning and control. In this paper, we introduce the precision navigation system and perform design and algorithm verification.

• Journal of Advanced Navigation Technology
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• v.14 no.5
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• pp.648-654
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• 2010

In this paper, a navigation system was designed, and performance tested in order to confirm the safety improvement of the GNSS(Global Navigation Satellite System)-based AGV(Autonomous Guided Vehicle) which used only position information on of GNSS. We developed DR(Dead Reckoning) navigation system that involve the use of GNSS abnormal positoning error detection and GNSS signal outage. The test results show that GNSS positioning error is detection can be archived with an error of more than 0.15m. In addition, the DR driving position error is 1.5m for an 8s GNSS positioning service outage.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.27-31
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• 2006

With the fast developing pace, the Galileo system is entering the navigation stage with high profile. At the same time, U.S. is accelerating his GPS modernization schedule, and Russian also begins to resuscitate their GLONASS. Moreover, Chinese Beidou system has also joined the satellite navigation family with low profile already. And of course Japanese QZSS even moves forward. Along with the bitter competition in technology, finance, market and even military affairs, all these systems will firmly benefit each other and massively extend the role of civil satellite navigation industry in the future. The Global Navigation Satellite Systems (GNSS) would be almost certain to include above major satellite navigation systems. Thus how to utilize the navigation satellite resource for world peace and promote the progress of mankind should be the key issue of this century.

• Journal of Advanced Navigation Technology
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• v.25 no.3
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• pp.194-202
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• 2021

Ionosphere, one of the largest error sources, can pose potentially harmful threat to single-frequency GNSS (global navigation satellite system) user even after applying ionospheric corrections to their GNSS measurements. To quantitatively assess ionospheric impacts on the satellite navigation-based applications using simulation, the standard deviation of residual ionospheric errors is needed. Thus, in this paper, we determine conservative statistical quantity that covers typical residual ionospheric errors for nominal days. Extensive data-processing computes TEC (total electron content) estimates from GNSS measurements collected from the Korean reference station networks. We use Klobuchar model as a correction to calculate residual ionospheric errors from TEC (total electron content) estimate. Finally, an exponential delay model for residual ionospheric errors is presented as a function of local time and satellite elevation angle.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.2
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• pp.424-431
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• 2017

These days land vehicle navigation system is a subject of great interest. The GNSS(Global Navigation Satellite System) is the most popular technology for out door positioning. However, The GNSS is incapable of providing high accuracy and reliable positioning. For that reason, we applied Network-RTK in vehicle to improve the accuracy of GNSS performance. In this network-RTK mode, the GNSS error are significantly decreased. In this paper, we explain ntrip client program for network-RTK mode and show the result of experiments in various environments.