• Journal of Positioning, Navigation, and Timing
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• v.12 no.4
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• pp.399-408
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• 2023

In this paper, we propose a solution that enables continuous indoor/outdoor positioning of smartphone users through the integration of Pedestrian Dead Reckoning (PDR) and GPS/WiFi signals. Considering that accurate step detection affects the accuracy of PDR, we propose a Deep Neural Network (DNN)-based technology to distinguish between walking and non-walking signals such as walking in place. Furthermore, in order to integrate PDR with GPS and WiFi signals, a technique is used to select a proper measurement by distinguishing between indoor/outdoor environments based on GPS Dilution of Precision (DOP) information. In addition, we propose a technology to adaptively change the measurement error covariance matrix by detecting measurement outliers that mainly occur in the indoor/outdoor transition section through a residual-based χ² test. It is verified through experiments on a testbed that these technologies significantly improve the performance of PDR and PDR/GPS/WiFi fingerprinting-based integrated pedestrian navigation.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.153-154
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• 2018

본 논문에서는 GPS 기능을 활용하여 고독한 현대인들을 위한 함께 식사할 수 있는 모임 어플리케이션을 설계하고 구현한다. 이 어플리케이션 사용은 크게 식사 모임의 주최자가 단체 그룹 방을 개설하고, 위치에 따라 함께 식사할 일반 사용자가 해당 그룹 방에 접속하는 방식이다. 그룹 방 입장 후 참여한 사용자는 주최자가 회원가입 시 입력한 카카오톡 SNS ID를 참고하여 식사를 원할 경우 주최자에게 메신저를 발송한다. 또한 그룹 방내에 참여한 사용자들은 GPS 기능을 활용해 수집된 사용자 위치 정보를 바탕으로 사용자 서로간의 위치 정보를 확인할 수 있다. 또한, 모임이 진행되는 날의 날씨 정보 제공을 위하여 날씨 API 기능도 함께 활용하여 정보를 제공한다. 이 어플리케이션의 구현으로 최근 1인 가구의 증가로 혼자 식사를 해결하는 혼밥족과 식사 상대가 없어 혼자 식사를 해결하는 현대인들의 외로운 식사 고민을 해결하고자 한다.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.3
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• pp.269-275
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• 2001

In land navigation applications, two kinds of GPS/DR integration schemes are commonly used; the loosely-coupled integration scheme and the tightly-coupled one. The loosely-coupled integration filter has a simple structure and is easy to implement. When the number of visible satellites is insufficient, however, it cannot calibrate the errors of the DR sensors. On the contrary the tigthly-coupled integration filter can sup-press the growth of the error in the DR output even when the visibility is poor. However, it has larger com-putation load due to the state dimension and is inconsistent because of the variation in the measurement dimension. This paper presents a GPS/DR integration scheme with dual integration mode. During when the number of visible satellites is sufficient, the proposed scheme operates in a loosely-coupled integration mode. When the visibility becomes poor, it is switched into a tightly-coupled integration mode. Consequently, the pro-posed scheme can calibrate the DR sensors even when the visibility is poor. In addition, its computation time remains constant even if the number of visible satellites increases. Field experiment results show that the performance of the proposed integration method is almost similar to that of the tightly-coupled one.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.10a
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• pp.49-55
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• 2006

Kinematic GPS provides quite good accuracy of position in cm level. Though K-GPS assures high precision measurement in cm level on the basis of an appreciable distance between a station and an observational point, but it has measurable distance restriction within 20 km from a reference station on land. So it is necessary to make out a simple and low-cost method to obtain accurate positioning information without distance restriction. In this paper, the velocity integration method to get the precise velocity information of ship is explained. Next two experimental results (Zig-zag maneuvering test and Williamson turn) as the ship's maneuvering test and also the experimental results of leaving and entering port as slow speed ship's movement were shown. In these experimental results, ship's course, speed and position are compared with those obtained by kinematic-GPS, velocity integration method and dead reckoning position using Gyro-compass and Doppler-log.

• Journal of Advanced Navigation Technology
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• v.14 no.6
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• pp.791-799
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• 2010

In this paper, integrated navigation algorithm is designed for land transport sector which is needed high accuracy and monitoring program is developed for lane departure warning. High accuracy position information which is possible lane separation is needed for lane departure warning, so position detection algorithm based GPS/DR which combine GPS with dead reckoning is proposed. For the verification of the designed integrated navigation algorithm, we drived to acquire data and showed post-processing experiment results with monitoring program. Vehicle driving movie and aerial photograph in monitoring program is designed to show lane keeping and lane separation.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.101-103
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• 2000

본 논문에서는 GPS(Global Positioning System)와 추측 항법 시스템인 DR(Dead Reckoning)을 혼합 구성한 수신보드의 운영을 위한 Embedded 운영체제를 설계하고 구현 하였다. 이 운영체제는 실시간으로 인공위성으로부터 수신되어지는 Raw Measurement 획득, GPS 항법, 자세 결정, 통합항법, 위성 추적을 수행하는 태스크들을 우선순위 기반으로 처리하는 선점형(Preemptive) 스케쥴링 방식을 채택한 실시간 운영체제 이다. 본 논문에서는 자세 결정용 GPS와 DR 센서를 이용한 통합시스템보드를 위한 실시간 운영체제의 개발 환경, 운영체제의 구조와 개발 내용에 대해 언급하였다.

• Journal of Korean Society for Geospatial Information Science
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• v.8 no.1 s.15
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• pp.73-84
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• 2000

Map matching technique is an essential part of the car navigation and other related positioning fields such as dead reckoning and GPS data logging upon the GIS database. This paper is to break down map matching techniques, to categorize them, and to propose a simple technique for GPS based map matching technique. For categorization of techniques, two approaches have been adopted. One is to only use geometric information, and the other is to use both geometric and topological information. Some pros and cons of each method have been described. In addition, a simple map matching technique, set forth in this paper, has been introduced for properly utilizing the advantage of GPS points after the absence of the chronic problem of selective availability, which had been prevailed recently. Some research opportunities and problems of the technique have also been discussed.

• ETRI Journal
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• v.34 no.3
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• pp.379-387
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• 2012

In this paper, an error compensation technique for a dead reckoning (DR) system using a magnetic compass module is proposed. The magnetic compass-based azimuth may include a bias that varies with location due to the surrounding magnetic sources. In this paper, the DR system is integrated with a Global Positioning System (GPS) receiver using a finite impulse response (FIR) filter to reduce errors. This filter can estimate the varying bias more effectively than the conventional Kalman filter, which has an infinite impulse response structure. Moreover, the conventional receding horizon Kalman FIR (RHKF) filter is modified for application in nonlinear systems and to compensate the drawbacks of the RHKF filter. The modified RHKF filter is a novel RHKF filter scheme for nonlinear dynamics. The inverse covariance form of the linearized Kalman filter is combined with a receding horizon FIR strategy. This filter is then combined with an extended Kalman filter to enhance the convergence characteristics of the FIR filter. Also, the receding interval is extended to reduce the computational burden. The performance of the proposed DR/GPS integrated system using the modified RHKF filter is evaluated through simulation.

• Journal of Advanced Navigation Technology
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• v.2 no.2
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• pp.75-83
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• 1998

This paper presents a low cost and high accuracy integrated Global Positioning System (GPS)/dead reckoning (DR) system. The integrated GPS/DR system is capable of providing highly accurate position data in real-time or in post processing. Based on the analysis of the main error source affecting the DR measurements, an eight-state mathematical model for the integrated system has been developed to represent these errors. This eight-state model has been used to build a nonlinear filter for the estimation of the state vector at every epoch when DR measurements are available. The accuracy of the system has been evaluated using 1Hz DR measurements and 3Hz continuous GPS position estimates. Through numerical simulation the system performance during periods with GPS outage has been investigated by comparing two different noise models. While one model is the position estimation filter containing a single noise model, the other filter includes two-level noise model. The simulation results have shown that the estimation filter containing two-level noise model for computing the position error of the integrated GPS/DR system yields better performance than that the filter including the single-level noise model does.

• The Journal of Korea Robotics Society
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• v.15 no.1
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• pp.16-23
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• 2020

This paper describes an alignment algorithm that estimates the initial heading angle of AUVs (Autonomous Underwater Vehicle) for starting navigation in a sea area. In the basic dead reckoning system, the initial orientation of the vehicle is very important. In particular, the initial heading value is an essential factor in determining the performance of the entire navigation system. However, the heading angle of AUVs cannot be measured accurately because the DCS (Digital Compass) corrupted by surrounding magnetic field in pointing true north direction of the absolute global coordinate system (not the same to magnetic north direction). Therefore, we constructed an experimental constraint and designed an algorithm based on extended Kalman filter using only inertial navigation sensors and a GPS (Global Positioning System) receiver basically. The value of sensor covariance was selected by comparing the navigation results with the reference data. The proposed filter estimates the initial heading angle of AUVs for navigation in a sea area and reflects sampling characteristics of each sensor. Finally, we verify the performance of the filter through experiments.