• The Journal of the Convergence on Culture Technology
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• v.8 no.3
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• pp.259-263
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• 2022

As urbanization progresses in Korea, megacities are being formed around the metropolitan area, the central area, and the southeast area. In addition, it is accelerating the development of urban air mobility (UAM) that can be operated by Mega City as a new growth engine industry in the future. At the same time, in order to become a space powerhouse, Korea plans to establish its own Korean positioning system (KPS) by 2035. Therefore, if urban air mobility and location information services provided by the Korean positioning system are used in combination, urban air mobility can be stably operated in future megacities.

• Journal of Navigation and Port Research
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• v.31 no.6
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• pp.509-514
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• 2007

The importance of the GPS is becoming larger and larger since it is one of the Global Navigation Satellite Systems and is regarded as a national infrastructure in the field positioning and timing Nowadays many researches avoiding and/or minimizing economic loss caused by unexpected fault of the GPS are being carried out because GPS fault can give a large impact on social security system as well as economic system NDGPS network which has been authorized by the Ministry of Marine and Fisheries provides services for marine users and evolved into a national infrastructure for GNSS users. Many researchers and engineers are doing research work in order to apply the NDGPS network to other fields. From this trend, it can be expected that the integrity and related functions for the NDGPS users will become more important than before. This paper analyzes integrity informations about the real GNSS fault and proposes method on integrity monitoring improvement of the DGPS reference station.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.12
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• pp.1310-1317
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• 2012

The Global Navigation Satellite System (GNSS) like US Global Positioning System (GPS) and EU Galileo are based on providing precise time and frequency synchronized ranging signals. Because of the exploitation of very precise timing signals these GNSS are used to provide both navigation and time distribution services. Moreover, because the positioning accuracy will improve as more satellites become available, we should expect that a combination of Galileo and GPS will provide better performance than those of both systems separately. However, Galileo will not use the same time reference as GPS and thus, a time difference arises - the GPS-Galileo Time Offset (GGTO). The navigation solution calculated by receivers using signals from both navigation systems will consequently contain a supplementary error if the GGTO is not accounted for. In this paper, we compared GPS Time (GPST) with Galileo Sytem Time (GST) and analyzed the effects of GGTO on positioning accuracy by simulation test. And then we also analyzed the characteristics of two representative GGTO correction methods such as the navigation message based method at system level and the estimation method at user level and propose the conceptual design of the novel correction method being capable of preventing previous method's problems.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.3
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• pp.487-498
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• 2013

A variety of location-based services applications, such as missing children search, emergency rescue requests and so on that requiring high-precision location information are increasing. Precision of GPS that can be used in most systems, however, is still low. In this paper, we design and propose a low cost differential global positioning system(DGPS) based on Web services using object-oriented modeling technique which can offer useable location service, variety device and safe service in wireless environment. The proposed system is designed with UML based on object-oriented modeling to maximize system recyclability and system scalability. In addition, we would like to improve the precision of the GPS in accordance with mobile station location when build low cost mobile station, location differential framework and server. We implement a communication interface based on web-service which is available in the form of a variety of services and can offer stable according to mobile environments. Finally, as performance evaluation results, we can obtain precision location within 1 ~ 2m through proposed system and 88.5% probability of less than 2m.

• Information and Communications Magazine
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• v.28 no.7
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• pp.52-58
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• 2011

최근 GPS와 Wi-Fi가 내장된 스마트폰의 보급으로 이를 활용한 위치기반서비스 (Location-based Service)가 각광을 받고 있다. 이를 통해 GPS를 이용한 실외 위치추정 및 항법서비스뿐만 아니라 실내에서도 Wi-Fi 신호를 이용하여 사용자의 위치를 추정하고 다양한 서비스를 제공받을 수 있게 되었다. 본 논문에서는 Wi-Fi를 이용한 실내 위치추정 기술의 기본원리에 대해 살펴보고, 이를 활용한 기술의 동향을 소개하고자 한다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.5
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• pp.343-351
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• 2015

It is well-known that even the DGNSS (Differential Global Navigation Satellite System) technique in navigation for ground vehicles can only provide several meters of accuracy, such that it is suitable for simple guidance. On the other hand, centimeter to millimeter level accuracy can be obtained by using carrier phase observables in the field of precision geodesy/surveying. In this study, a preliminary study was conducted to apply NRTK (Network-RTK) by NGII (National Geographic Information Institute) to ground vehicle navigation. Onboard GNSS receivers were used for NRTK throughout the country, and the applicability of NRTK on navigation was analyzed based on NRTK surveying results. The analysis shows that the overall ambiguity fixing rate of NRTK is high and is therefore possible to apply it for navigation. In urban areas, however, the fixing rate decreases sharply, therefore, it needs to employ a method to minimize the effect of the float solutions, which can reach up to 10 meters. It is still feasible to obtain a centimeter level of accuracy in some area using NRTK under certain conditions. But, the ambiguity fixing rate of FKP falls down to 55% for high speed vehicles, and so the surveying accuracy should be determined by considering various factors of surveying environments. In addition, it is difficult to fix ambiguities using single-frequency GPS receivers. Finally, several suspicious NRTK(FKP) connection problems occurred during atmospheric disturbances (phase two or up), which should be investigated further in upcoming research.

• Journal of Advanced Navigation Technology
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• v.19 no.1
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• pp.1-6
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• 2015

Due to the rapid increase in air traffic worldwide, ICAO has replaced the existing navigation equipment with equipment based on satellite navigation. As a part of that work, ICAO was planning to replace conventional takeoff and landing service using ILS with GBAS. Unlike ILS, GBAS which uses precision approach service inducing aircraft to airport and satellite based augmentation system providing precise position information service surrounding airport is capable of providing a required performance by only a system, regardless of the number of systems, and has an advantage that it is possible curved approach. In this paper, fuel reduction of ILS approach procedures and GBAS curved approach procedures is estimated and determined by flight test in Taean Airport.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.12a
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• pp.3-8
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• 2004

가정에서건 사무실에서건 혹은 이동 중에도 무선 이동 통신, 인터넷, 각종 디지털 기기를 통해 자유롭게 정보를 교환하고 원하는 서비스를 이용할 수 있는 새로운 네트워크 시대가 열리고 있다. 단순한 운송수단이었던 자동차도 무선 통신과 GPS 기술을 바탕으로 차내 이동형 정보서비스를 지원하는 텔레매틱스 서비스를 도입하면서, 도로상에서 다양한 서비스를 이용할 수 있는 환경을 제공하고 있다. 이로 인해 텔레매틱스 서비스를 위한 핵심기술 개발에 대한 수요도 증가하고 있으며, 그 중에서도 사용자 및 차량으로부터의 서비스 요청을 처리하고, 다양한 컨텐츠 제공자 및 서비스 제공자와의 연계를 지원하기 위한 텔레매틱스 서버에 대한 필요성이 증대되고 있다. 본 논문에서는 항법 맵, POI, 실시간 교통정보 등 텔레매틱스 핵심 컨텐츠를 상호 연계하여 이를 사용자에게 효율적으로 서비스하기 위한 텔레매틱스 컨텐츠 서비스 서버를 설계하였다. 이를 통해 향후 텔레매틱스 서비스를 위한 시스템 구축 시 상호운용성과 확장성을 제공함으로써, 국내 텔레매틱스 서비스의 조기 활성화에 기여할 수 있을 것이다.

• Journal of Navigation and Port Research
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• v.29 no.10 s.106
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• pp.877-882
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• 2005

It is necessary that Fail-Safe Seaway technology providing a continuous navigation solution though fault of navigation system is occurred in sea. This paper focus on signal processing of GPS receiver, one of receivers using the software radio technology to implement a integrated radio navigation system including satellite-based and ground-based navigation systems. It is difficult to implement the software GPS receivers using a commercial processor because of the heavy computational burden for processing the GPS signals in real time. This paper proposes an efficient multi-bit GPS signal processing scheme to reduce the computational burden for processing the GPS signals in the software GPS receiver. The proposed scheme uses a compression concept of the multi-bit replica signals and patterned look-up table method to generate the correlation value between the GPS signals and the replica signals.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1824-1833
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• 2016

In this paper, we propose networked airborne relay-based positioning scheme (N-ARPS) based on time division multiple access (TDMA) networks to improve the performance of relative navigation (RelNav). To integrate the ARPS into TDMA, there are three problems such as slot allocation, selection of airborne relays, and method for signal loss to be solved. A subframe of N-ARPS is designed to assign the slots for broadcast and relay of navigation signals consecutively to minimize the effect of mobility. The selection algorithm determines the optimum set of airborne relays by selecting evenly distributed nodes depending on their distances to the master station. Finally, we uses precise position location information (PPLI) messages, which are received in data transmission period, to estimate a user position when the navigation signals are missing. The simulation results indicate that N-ARPS significantly improves user accuracy over RelNav.