• Journal of Institute of Control, Robotics and Systems
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• v.18 no.11
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• pp.1034-1039
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• 2012

In this paper, a structure of precise positioning based on satellite navigation system is proposed. The proposed system is consisted with three parts, range domain filter, navigation filter and position domain filter. The range domain filter generates carrier phase-smoothed-Doppler and Doppler-smoothed-code measurements. And the navigation filter calculates position and velocity using double-differenced code/carrier phase/Doppler measurements. Finally, position domain filter smooth position error, and it means enhancement of positioning performance. The proposed positioning method is evaluated by trajectory analysis using precise map date. As a result, the position error occurred by multipath or cycle slip was reduced and the calculated trajectory was in true lane.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.9
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• pp.963-968
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• 2008

A new method to deal with GPS indoor positioning by means of time synchronized switching GPS repeater has been developed by authors[1]. But the developed indoor positioning system has problems. Therefore, we proposed a method for indoor positioning using GNSS Repeater-Assisted. To solve the 3-dimensional user's position, the 4 or more retransmission antennas are needed in the previously proposed methods. If a GPS repeater periodically transmits the signal like as pseudollite, the information for assisting an acquisition and tracking can be informed to receiver. Then, the user position can be calculated using the induced weak signal. The advantage of the proposed algorithm is use of only 1 re-transmission antenna because the re-transmitted signal are not used for positioning but used for assisting an acquisition and tracking weak signals induced indoor. We analyze the propose algorithms through the experiment and performed the test of feasibility.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.1
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• pp.1-9
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• 2008

According to the ubiquitous trend, the needs for the context based application service have been increased. These services take on Location Based Service which is based on the current location of users. It is widely used that localization techniques use GPS or ground wave and more efficient and accurate methods have been studied. Recently, not only services which targeted outdoor but also services which targeted indoor, for example home services and facility guidance of the building come into the spotlight. In case of the outdoor positioning area, COTH (Commercial Off-The-Shelf) has been released and used but relatively it doesn't produce an outcome in the indoor positioning area. Therefore, this paper Proposes the indoor positioning technique using wireless LAN (Local Area Network) which is one of the widely used wireless communication technique. It analyzes the typical WLAN location positioning methodology has been studied and their advantage and disadvantage also suggests how to design and implement the specific WLAN positioning system. In addition, it suggests new methods that progress the accuracy of the existing systems and improve the efficient computation.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.1203-1206
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• 1993

Fuzzy techniques are applied to the positioning of an elastic beam. The advantage is that the system model is not needed. A simple fuzzy friction compensator is also used. The final position is achieved within 3/2 the period of the fundamental mode. A fuzzy set of rules is applied for large-angle positioning, with adaptations that reduce the effects of shock. In this case, the final position is achieved within two fundamental periods. There is typically some final error attributed to the dry friction.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.7
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• pp.684-690
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• 2015

This paper presents a modified residual-based EKF (Extended Kalman Filter) for performance improvement of indoor positioning using WiFi RSSI (Received Signal Strength Indicator) measurement. Radio signal strength in indoor environments may have irregular attenuation characteristics due to obstacles such as walls, furniture, etc. Therefore, the performance of the RSSI-based positioning with the conventional trilateration method or Kalman filter is insufficient to provide location-based accurate information services. In order to enhance the performance of indoor positioning, in this paper, error analysis of the distance calculated by using the WiFi RSSI measurement is performed based on the radio propagation model. Then, an IARM (Irregularly Attenuated RSSI Measurement) error is defined. Also, it shows that the IARM error is included in the residual of the positioning filter. The IARM error is always positive. So, it is presented that the IARM error can be estimated by taking the absolute value of the residual. Consequently, accurate positioning can be achieved based on the IEM (IARM Error Mitigated) EKF with the residual modified by using the estimated IARM error. The performance of the presented IEM EKF is verified experimentally.

• Journal of Positioning, Navigation, and Timing
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• v.6 no.4
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• pp.205-210
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• 2017

Multi-Global Navigation Satellite System (GNSS) can significantly improve the positioning accuracy and convergence speed. The reliability and availability of multi-GNSS precise point positioning (PPP) is steadily increasing with the rapid development of GNSS satellites. In this study, multi-GNSS PPP analysis is performed to compare the positioning precision by processing the observations from different GNSS systems (GPS, GLONASS, Galileo and BeiDou). To improve the positioning performance of the multi-GNSS PPP, we employed the weighed measurement noise (WMN) method. After applying WMN method to multi-GNSS PPP, positioning precision is improved by approximately 26.3% compared to the GPS only solutions, and by approximately 9.1% compared to combined GPS, GLONASS, and Galileo PPP.

• Journal of Positioning, Navigation, and Timing
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• v.7 no.1
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• pp.15-24
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• 2018

This study analyzed positioning accuracy of the multi-differential global navigation satellite system (DGNSS) algorithm that integrated GPS, GLONASS, and BDS. Prior to the analysis, four sites of which satellite observation environment was different were selected, and satellite observation environments for each site were analyzed. The analysis results of the algorithm performance at each of the survey points showed that high positioning performance was obtained by using DGPS only without integration of satellite navigation systems in the open sky environment but the positioning performance of multi-DGNSS became higher as the satellite observation environments degraded. The comparison results of improved positioning performance of the multi-DGNSS at the poor reception environment compared to differential global positioning system (DGPS) positioning results showed that horizontal accuracy was improved by 78% and vertical accuracy was improved by 65% approximately.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.4
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• pp.1122-1140
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• 2024

The importance of indoor positioning has grown in numerous application areas such as emergency response, logistics, and industrial automation. In ships, indoor positioning is also needed to provide services to passengers on board. Due to the complex structure and dynamic nature of ship environments, conventional positioning techniques have limitations in providing accurate positions. Compared to other indoor positioning technologies, Bluetooth 5.1-based indoor positioning technology is highly suitable for ship environments. Bluetooth 5.1 attains centimeter-level positioning accuracy by collecting In-phase and Quadrature (IQ) samples from wireless signals. However, distorted IQ samples can lead to significant errors in the final estimated position. Therefore, we propose an indoor positioning method for ships that utilizes a Deep Neural Network (DNN) combined with IQ fingerprint maps to overcome the challenges associated with accurate location detection within the ship. The results indicate that the accuracy of our proposed method can reach up to 97.76%.

• Journal of Positioning, Navigation, and Timing
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• v.13 no.3
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• pp.301-307
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• 2024

In this paper, we propose a round trip time (RTT)-enabled Doppler-based positioning method considering the low earth orbit (LEO) satellite visibility restriction. Doppler-based positioning typically requires visibility to at least eight satellites, which is often unfeasible due to the limited coverage of LEO satellites, as beamforming technique is applied to current LEO satellites. To solve this problem, we utilize the RTT measurements, assuming that a communication link exists between the user equipment (UE) and LEO satellites. We employ the Newton-Raphson method to estimate the UE position with RTT and Doppler measurements. We analyze the positioning performance of the considered framework via simulation, demonstrating its performance in 3D positioning errors under varying satellite numbers and measurement errors.

• 한국ITS학회:학술대회논문집
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• v.2007 no.10
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• pp.186-191
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• 2007