• Korean Journal of Remote Sensing
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• v.34 no.6_1
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• pp.1131-1142
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• 2018

The autonomous vehicles are being developed and operated widely because of the advantages of reducing the traffic accident and saving time and cost for driving. The vehicle localization is an essential component for autonomous vehicle operation. In this paper, localization algorithm based on sensor fusion is developed for cost-effective localization using in-vehicle sensors, GNSS, an image sensor and reference images that made in advance. Information of the reference images can overcome the limitation of the low positioning accuracy that occurs when only the sensor information is used. And it also can acquire estimated result of stable position even if the car is located in the satellite signal blockage area. The particle filter is used for sensor fusion that can reflect various probability density distributions of individual sensors. For evaluating the performance of the algorithm, a data acquisition system was built and the driving data and the reference image data were acquired. Finally, we can verify that the vehicle positioning can be performed with an accuracy of about 0.7 m when the route image and the reference image information are integrated with the route path having a relatively large error by the satellite sensor.

• Journal of Korea Multimedia Society
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• v.9 no.9
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• pp.1222-1230
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• 2006

Location-Based Service (LBS) is a service provided to the user based on the user's current geographic location. Since LBS provides a higher value-added service, LBS has been applied on various businesses, industries and even on personal lives. Positioning users is the essential technology in building an LBS system. Thanks to GPS (Global Positioning System), Positioning outdoor is successfully used in practice. However, there is not a general solution for indoor positioning yet, even though many strategies for indoor positioning have been introduced. One of the reasons for the lack of successful indoor positioning is that most of the existing indoor positioning strategies require special equipments dedicated for positioning. This paper introduces an indoor positioning strategy that does not require any additional equipments. Integrating our indoor positioning strategy with GPS-based outdoor positioning, we have implemented an indoor-outdoor positioning system. Experimental results of the system is also introduced.

• Proceedings of the Korea Contents Association Conference
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• 2014.11a
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• pp.75-76
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• 2014

본 연구는 국토 공간정보 기반으로 새로운 위성측량 기술과 USN 측정기술을 접목하고 구체적인 AGS 공법과 같은 그라우팅 기술의 적용으로, 방재를 필요로 하는 주요 수리시설물에 대한 정밀한 변위와 거동을 모니터링 할 수 있는 첨단기술의 개발 및 적용은 국가적으로 매우 중요한 과제이며 실용성이 높은 기술연구이다. 외부공간에서의 GNSS 위성측위 방식의 초정밀의 위치변위를 실시간으로 추적하고 그에 영향을 주는 환경인자인 온도, 습도, 조도, 이산화탄소, 질소, 함수비, 소음진동 등은 무선 USN에 의하여 실시간으로 동시에 수집하여 통합적으로 분석 적용하여 방재시설의 적절한 대응시기를 찾아낼 수 있을 것으로 판단되며, 특히 정밀한 변위 관측을 필요로 하는 안전진단 및 방재를 필요로 하는 시설물 안전관리 분야에서 다방면으로 크게 활용할 수 있는 방안을 모색하였다.

• Journal of Navigation and Port Research
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• v.36 no.6
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• pp.429-435
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• 2012

Although GNSS hardware and software technologies have been steadily advanced, it is still difficult to obtain reliable positioning results in the area with lots of signal blockage. In this study, algorithms for integrated GPS and GLONASS double difference relative positioning were developed and its performance was validated via simulations of signal blockages. We assumed that signal blockages are caused by high-rise buildings to the east, west, and south directions. And then, GPS-only and integrated GPS/GLONASS positioning accuracy was analysed in terms of 2-dimensional positioning accuracies. Compared with GPS-only positioning, the positioning accuracy of integrated GPS/GLONASS improved by 0.3-13.5 meters.

• Information and Communications Magazine
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• v.21 no.5
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• pp.46-55
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• 2004

최근에 새롭게 관심이 고조되고 있는 텔레매틱스는 통신과 정보기술(Informatics)의 합성어로 무선망을 통한 음성 및 데이터통신과 인공위성을 이용한 위치정보시스템(GPS)을 기반으로 차량에 정보를 주고받음으로써 새로운 부가 서비스를 제공하는 기술을 의미한다. 좀 더 구체적으로 말하면 측위 시스템과 이동통신망을 이용해 운전자와 탑승자에게 위치정보, 교통정보, 최적경로안내, 응급상황에 대한 긴급구난, 원격차량진단, 인터넷 이용(금융거래, 뉴스, e-메일, VOD 등) 등 차량에서의 "Mobile Office" 환경을 제공하는 기술로 설명할 수 있다.(중략)

• 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.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.1
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• pp.71-78
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• 2016

In the paper, we predict the number of multi-GNSS satellites and visible satellites with the navigation satellite launch plans and their nominal orbit parameters. Based on the methodology, the multi-GNSS navigation performance and DOP (Dilution of Precision) variation from 2015 to 2020 were forecasted by the Matlab simulation. To calculate the position using the multi-GNSS constellation, we determined the time-offset between the two different systems. Two different algorithms were considered for the sake of time-offset determination; that of each was applied to system level and user side. Also, the results from two algorithms were compared for evaluating each performance. For the reality, we applied the 3D map information to the simulation, which is expected to contribute for predicting the future navigation performance in urban canyon.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.6
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• pp.609-616
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• 2017

National Geographic Information Institute has established a plan that preoccupies UCPs (Unified Control Points) at 2~3km intervals in urban areas by considering the distance between existing UCPs by satellite images and aerial photographs in 2015. In this study, we discussed the method of selecting the locations of optimal UCPs by simulating GPS reception environment in candidate sites for UCPs using GIS. For this purpose, we selected new candidate sites for installing UCPs using satellite images and aerial photographs, and analyzed the GPS reception environment by calculating the visibility distance from buildings around UCPs using GIS skyline analysis. The number of and the arrangement of visible satellites that are capable of GPS satellite reception from the viewpoint of sky view were showed by GIS skyline analysis. Quality evaluation results of GPS observation data were compared with average PDOP calculated from hourly PDOP and TEQC in two points of Sungkyunkwan University during 8 hours. As a result of GPS reception environment using GIS, if the PDOP increases, the data acquisition rate is lowed, and the multipath error and the cycle slip are increased. Thus, this study verified that the quality of GPS observation data can be secured by constructing three-dimensional spatial information and simulating PDOP when preoccupying multiple UCPs using GIS.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.6
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• pp.659-667
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• 2009

In this study, an integrated GNSS Simulator called Inha GNSS Simulation System (IGSS) using 3D spatial information was developed and validated. Also positioning availability and accuracy improvement were evaluated under the integrated GNSS environment using IGSS. GPS and GLONASS satellite visibility predictions were compared with real observations, and their frequency of error were 6.4% and 7.5%, respectively. To evaluate positioning availability and accuracy improvement under the integrated GNSS environment, the Daejeon government complex area was selected to be the test site because the area has high-rise buildings and thus is susceptible to signal blockages. The test consists of three parts: the first is when only GPS was used; the second is when both GPS and GLONASS were simulated; and the last is when GPS, GLONASS, and Galileo were used all together. In each case, the number of visible satellites and Dilution Of Precision were calculated and compared.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.05a
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• pp.210-212
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• 2019

위성항법시스템의 취약성에 따른 보완 시스템의 필요가 높아지면서, eLoran 시스템이 가장 현실적인 대안으로 인정받고 있다. 우리나라도 서해 일부 지역에서 eLoran 시스템의 테스트베드 구축 사업을 진행 중에 있다. 전 해양지역에 안정적인 서비스를 제공하기 위해서는 추가적인 송신국 설치가 필요하지만. 여러가지 현실적인 이유로 인해 추진되기 어렵다. 이런 문제를 해결하기 위해 기존의 NDGNSS 기준국을 활용한 측위기술이 개발되고 있다. 이미 운영 중인 NDGNSS 기준국을 활용하면 전 해상에서 탄력적 항법시스템 운용이 가능해질 수 있다. 본 논문에서는 eLoran 시스템과 NDGNSS의 기준국을 활용한 지상파 통합항법시스템의 성능을 예측할 수 있는 시뮬레이션 툴을 제작 하였다. ITU에서 배포한 송출 주파수와 거리에 따른 신호 세기, 대기잡음 등을 고려해 Cramer-Rao Lower Bound로 수신 신호의 측정 거리 오차를 계산하였다. 또한 한빛호가 항해하면서 수집한 DGPS 신호를 통해 실질적인 대기잡음을 추정하는 방법을 사용해 기존보다 정확한 SNR 계산이 가능해졌다. 해당 결과는 추후 진행될 지상파통합항법시스템 개발에 유용하게 활용될 것으로 기대된다.