• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.2
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• pp.101-110
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• 2000

This study focuses on examination of the availability and effectiveness about application of the differential GPS methods for navigation and acquisition of the geo-spatial information. For this, the algorithms related to a navigation solution and differential GPS were implemented in MATLAB code, a number of software simulations on test model were carried out to assess its performance, comparing the results with those obtained from the commercial software. Expecially, the results coming from tracking test on test model of the OO's WADGPS which is the commercial real-time satellite-based augmentation system via geostationary satellite (GEOs), which has been investigated with those from the above GPS methods. And also, the accuracy of absolute positioning by Navigation solution and WADGPS before and after SA-off has been compared. The above results show that DGPS methods are very reliable and efficient methods for acquisition of the geo-spatial information.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.640-642
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• 2021

In order to collect a lot of data clearly and efficiently, it is essential to know the locations of the current facilities and analyze the movement data. The current location collection technology can collect data using a GPS (Global Positioning System) sensor, but in the case of GPS, it has strong straightness and low diffraction and reflectivity, making it difficult to position indoors. It is impossible to measure the distance between the server and the client because the signal sensitivity cannot be received. This paper implements an indoor positioning system using beacons and scanners in Raspberry Pi 3 B+. It controls Advertise Mode and Connection Mode at the same time using the scanner algorithm.

• Journal of Auto-vehicle Safety Association
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• v.9 no.3
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• pp.24-30
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• 2017

This paper presents the development of laser scanner based static obstacle detection algorithm for vehicle localization on lane lost section. On urban autonomous driving, vehicle localization is based on lane information, GPS and digital map is required to ensure. However, in actual urban roads, the lane data may not come in due to traffic jams, intersections, weather conditions, faint lanes and so on. For lane lost section, lane based localization is limited or impossible. The proposed algorithm is designed to determine the lane existence by using reliability of front vision data and can be utilized on lane lost section. For the localization, the laser scanner is used to distinguish the static object through estimation and fusion process based on the speed information on radar data. Then, the laser scanner data are clustered to determine if the object is a static obstacle such as a fence, pole, curb and traffic light. The road boundary is extracted and localization is performed to determine the location of the ego vehicle by comparing with digital map by detection algorithm. It is shown that the localization using the proposed algorithm can contribute effectively to safe autonomous driving.

• Journal of Satellite, Information and Communications
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• v.7 no.2
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• pp.104-109
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• 2012

Currently, GPS(Global Positioning System) is used to find user location information. However, in some cases, especially in urban environments, we receive unreliable location information deu to multipath fading. In order to resolve this problem, we propose a closely coupled positioning technique where GPS signal is combined with QZSS signal. Also we proposed and analyze a combining algorithm of GNSS and Wi-Fi signals to get closely coupled location information by referring AP information. Finally, this paper proposes a combined GPS/QZSS/Wi-Fi navigation algorithm to improve navigation performance, and it is verified by testing of car deriving according to availability and accuracy standard.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.6
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• pp.1243-1251
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• 2017

When a Ship sails in the ocean, it is significant to find one's position for safe navigation. Most of ships have been using GPS navigation since its development after 1990's. The celestial navigation was used as the navigation method when sailing in the ocean, but time-consuming process such as complicated calculation and plotting the result on chart diminished its utilization. The thesis explains convenience and utilization of existing celestial navigation by resolving challenges it has. As a way of enhancing the celestial navigation, the author developed a software which incudes a numerical formula based on the previous calculation process. When a navigator inputs the altitude of sun, GHA and dec into computer while sailing, the position of the ship will be displayed as the coordinates. The improved method thus reaffirmed the usefulness of the celestial navigation and will greatly serve as means of navigation in the occurrence of distress. Abstract should be placed here.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.4
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• pp.109-117
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• 2010

With the advent of new technologies such as HSDPA, WiBro(Wireless Broadband) and personal devices, we can access various contents and services anytime and anywhere. A location based service(LBS) is essential for providing personalized services with individual location information in ubiquitous computing environment. In this paper, we propose mapping algorithm for error compensation of indoor localization system. Also we explain filter and indoor localization system. we have developed mapping algorithms composed of a map recognition method and a position compensation method. The map recognition method achieves physical space recognition and map element relation extraction. We improved the accuracy of position searching. In addition, we reduced position errors using a dynamic scale factor.

• Journal of Satellite, Information and Communications
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• v.5 no.1
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• pp.54-57
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• 2010

The navigation system like GPS which is core technology is based on Code Division Multiple Access(CDMA) techniques. To receive satellite signal smoothly in CDMA, received signals have to synchronize with spread code. In this paper, we focus on the code tracking methods among synchronization techniques. The conventional delay lock loop(DLL) is unsuitable for multi-path channel. We will introduce how it overcomes distortion by multi-path. We will propose method that separates out multi-path signals and tracks the each path signals. And we will confirm performance of proposed method using Spirent simulator.

• Annual Conference of KIPS
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• 2018.10a
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• pp.991-994
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• 2018

최근 사용자의 위치 정보를 기반으로 응용서비스를 제공하는 위치 기반 서비스가 각광 받고 있다. 그 중 실내 위치 정보 수집을 위한 방법 중 하나로 비콘을 사용하고 있다. 비콘을 이용하여 실내공간에서 사용자의 위치를 계산하는 방법은 비콘과 단말기와의 거리를 측정하고, 측위 알고리즘을 적용하여 단말기의 위치를 계산하는 것이다. 하지만 비콘이 단말기와의 거리를 측정하는데 사용하는 RSSI는 주변 환경에 영향을 많이 받아 측정 시 오차가 발생한다. 따라서 정확한 실내 측위를 위해서는 불안정한 RSSI를 보정할 필요가 있다. 본 논문에서는 RSSI의 오차 범위를 평균필터와 칼만필터, 그리고 신호의 정확도 개선 과정을 통해 보정하고 그 결과를 제시한다.

• Annual Conference of KIPS
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• 2022.05a
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• pp.122-123
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• 2022

최근 들어 인공지능에 대한 발달과 많은 매체들로 인해 사람들의 관심이 증가하고 있다. 또한 GPS 나 Beacon 과 같이 위치 측위 기술이 증가함에 따라 실외 측위 기술이 많이 발달되었고, 실내에서도 사용자의 정확한 위치를 측정할 수 있는 기술들이 발달되고 있다. 본 논문에서는 RNN 알고리즘을 이용하여 비콘을 통해 수집된 사용자의 반복적이고 순차적인 위치정보, 타임스탬프 데이터를 학습시키고 ECG 를 결합하여 사용자 인증을 하여 사용자의 시간별 위치 예측과 이상 징후 탐지 시스템을 제안하고자 한다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.2
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• pp.123-129
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• 2015

The Kalman filter has been widely used in the kinematic GPS positioning due to its flexibility and efficiency in computational points of view. At the same time, the relative positioning technique also provided the high precision positioning results by removing the systematic errors in the measurements significantly. However, the positioning quality may be degraded following to longer in baseline length. For this case, it is required that the remaining atmospheric effects, such as double-difference ionospheric delay and zenith wet delay, should be properly modeled by examining the characteristics of the stochastic processes. In general, atmospheric effects are estimated with the assumption of random walk, or the first-order Gauss-Markov stochastic process, which requires the precise modeling on the corresponding process noises. Therefore, we determined and provided the parameters for modelling the process noises for atmospheric effects. The auto-correlation functions are empirically determined at first, and then the parameters are extracted from the empirical auto-correlation function. In fact, the test results can be either applied directly, or used as guidance values for the modeling of process noises in the kinematic GPS positioning.