• Journal of Satellite, Information and Communications
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• v.10 no.1
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• pp.71-76
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• 2015

In this paper, we developed the hardware GPS signal generator for generating a satellite navigation signal synchronized with Live GPS signal signals and analyzed the performance of signal genterator thorough the experiment For a hardware implementation of the GPS navigation signal synchronous generator, the GPS module may receive a GPS signal in order to generate the same signal as the operation that is transmitted from the current GPS satellite and the synchronized time information and the GPS satellites using the Novatel Inc. OEMStar.In. For generating the GPS synchronization signal, the GPS navigation signal generator was adjusted to a reference clock using the GPS clock synchronous information provided by the GPS receiving module and GPS signals also generated in consideration of the delay of the internal hardware of the generator. In this paper, we analyzed the effect of the receiver via the signal switching between Live GPS signal and generates a signal to measure the performance of the GPS navigation synchronization signal generator. It was confirmed that by the seamless operation of the signal even the moment that the switching of the generated signal from Live GPS signal has occurred through experimentation.

• 한국경영정보학회:학술대회논문집
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• 2007.06a
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• pp.603-607
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• 2007

GPS 수신기의 지속적인 가격 하락과 GPS 기반의 다양한 위치기반서비스 개발로 인하여 개인 휴대용 GPS 수신기의 보급이 확대되고 있다. 이동객체의 위치 및 시간 정보를 포함하고 있는 GPS 데이터를 분석하면 이전에는 불가능했던 이동패턴을 파악하고 이해하는 것이 가능해진다. 이동객체 데이터의 저장과 분석에 관한 연구들이 진행되고 있지만, 이동객체의 속성에 따른 다차원적 이동패턴 분석에 관한 연구는 찾아보기 힘들다. 본 연구는 개인 휴대용 GPS 수신기를 통해 수집된 이동 데이터와 이동객체의 속성 데이터를 통합하여 이동객체의 시공간적 특성을 다차원적으로 분석할 수 있는 데이터마트를 구현하고 시각적으로 표현하였다. 이러한 과정을 통해 GPS 데이터를 이용한 이동패턴 분석의 유용성과 문제점을 탐색적으로 살펴보았다.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2004.03a
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• pp.499-505
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• 2004

현재 국내에서 활발히 이루어지고 있는 GPS 정밀측지측량은 획득된 GPS 관측값의 결과값이 GPS 기준점의 기하학적 강도와 분산계수의 상관관계의 연관성과의 분석없이 사용되고 있는 문제점을 파악하고 육지와 해상의 통합지리정보시스템구축을 위한 수치지도와 전자해도의 통합투영의 필요성에 의해서 이루어졌다. 본 연구의 목적은 크게 GPS 관측값의 정밀도를 향상시키는 방법과 수치지도와 전자해도의 통합투영으로 GPS 기준점들을 이용한 수치지도와 전자해도상의 경계선 오차량을 비교검토를 통해 수치지도와 전자해도의 통합관리의 방향을 제시하는데 있다. GPS 관측값의 정밀도 향상을 위한 방법제시를 위하여 GPS 망조정에 사용되는 3점의 기준점에 대한 기하학적인 강도에 따른 정밀도 분석방법과 분산계수의 변화에 따른 GPS 관측값들의 정밀도 분석방법으로 나누어 검토하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.10
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• pp.2223-2229
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• 2010

The integrity monitoring of anomalous GPS signal have been researched because of the degradation of GPS satellite performance. It is known that anomalous GPS signal can occur by failure of GPS satellite, sudden increase of ionosphere delay error, SA, wrong modeling for navigation parameters from control segment, and an electromagnetic wave interference, etc. In case of GPS anomaly by satellites can arise from carrier frequency, code and navigation message. In this paper, the scenarios with navigation message errors were made by using GPS simulator, and the influences of GPS navigation message error to receiver were analysed. The anomalies of preamble, bits related TOW count message, subframe ID in HOW, bits related satellite healthy, and the other navigation message errors were described and simulated. Also, the number of satellites, DOP and pseudorange are analyzed to know how the anomalous signal can affect on GPS receiver.

• Journal of Korean Society for Geospatial Information Science
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• v.15 no.4
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• pp.41-50
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• 2007

This study aims to suggest efficient setting up of GPS (Global Positioning System) for cadastral surveying. In order to perform it effectively, worldly used modern surveying technology GPS introduced. In a practical analysis, GPS observation had been performed in the research area and the results had been compared and analysed with the results of Total Station. As a results, it is shown that GPS is more efficient rather than current surveying method in terms of time, cost and economy. The results of GPS surveying were included in the scope of error tolerance, being accepted by cadastral laws, showing high accuracy of GPS surveying method. With the results of analysis, how to application of GPS for cadastral surveying was suggested.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.2
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• pp.163-171
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• 2014

Based on the GPS/IMU integration, the car navigation has unstable conditions as well as drastically reduces accuracies in urban region. Nowadays, many cars mounted the camera to record driving states. If the ground coordinates of street furniture are known, the position and attitude of camera can be determined through SPR(Single Photo Resection). Therefore, an estimated position and attitude from SPR can be applied measurements in Kalman filter for updating errors of navigation solutions from GPS/IMU integration. In this study, the GPS/IMU/SPR integration algorithm was developed in loosely coupled modes through extended Kalman filters. Also, in order to analyze performances of GPS/IMU/SPR, simulation tests were conducted in GPS signal reception environments and the GCPs (Ground Control Points) distributions. In fact, the position and attitude gathered from GPS/IMU/SPR integration are more precise than the position and attitude from GPS/IMU integration. When IPs (image points), corresponded to GCPs, were concentrated in the center of image, the position error in the optical axis respectively increased. To understand effects from SPR, we plan to carry additional test on the magnitude of GCP, IP and initial exterior orientation errors.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.3
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• pp.283-292
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• 2005

After USA removed the Selective Availability (SA), Global Positioning System (GPS) has monopolized the world market and other countries have been depended on GPS, absolutely. So the other countries, Russia, European Community (EC) and Japan, which apprehend to monopolize in technical and strategic parts, are developing the next generation GNSS including GLONASS Galileo and JRANS. And the countries are planning to provide the another GNSS. This research has focused on the next generation GNSS system based on GPS and Galileo system with developing a GNSS simulation software, named as GlMS2005, which generates and analyzes satellite constellation and measurements. Based on the software, a variety of simulation tests have been carried out to recognize limits of GPS-only system and potential benefits of integrated GPS/Galileo positioning in terms of satellite geometry strength and solution accuracy.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.51-51
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• 2020

본 연구에서는 기수역에서의 GPS 전자부자를 활용한 계측 데이터와 염분측정 데이터를 비교분석하여 GPS 전자부자의 거동 특성이 담수의 실제 거동특성과 같이 일치하게 나타나는지 확인하고, GPS 전자부자에 대한 활용성을 증명하고자 하였다. 기수역에서의 담수와 해수의 분포를 확인하기 위해서는 많은 인력과 장비를 소모하며 수리량과 염분도에 대한 측정을 통해 분석을 할 수 있는데, 대표적인 수리량 측정장비인 ADCP 또는 ADV는 각종 측정 한계들이 존재한다. 따라서 이러한 기수역에서의 수체 구간별 흐름 특성이 어떻게 나타나는지 확인하기 위해서 GPS 전자부자를 활용하고자 하였으며. GPS 전자부자의 데이터와 수직방향으로 측정한 염분도 데이터와 비교하고자 하였다. 수영강 좌수영교 상류 1km지점에서 주입하였으며 간조 시와 만조 시에 유하시켜 수영강에 위치한 좌수영교와 수영교에서 각각 좌측, 중간, 우측에서 수심방향으로 측정한 염분도를 상층 중층 하층으로 평균하여 비교하였다. 본 연구에서 사용한 GPS 전자부자는 표면부자이기 때문에 만조 시 하류방향으로 더 뻗어 나가는것으로 확인하였고, 간조 시에는 흐름이 더디거나 정체하는 것으로 나타났다. 이러한 계측 결과는 담수의 흐름 특성과 일치하게 나타나는 것을 확인하였고 이러한 GPS Floater를 활용한다면 굳이 각종 수질을 측정하지 않아도 흐름 상황으로 간조인지 만조인지에 대한 상황과 염분 분포를 대략적으로 알 수 있다. 이러한 GPS 전자부자의 위치데이터와 시간을 잘 이용한다면 ADCP의 유속 측정에 대한 단점을 보완할 수 있는 Lagrangian 타입의 유속을 측정 할 수 있다. 이러한 GPS 전자부자를 하천에서 선주입으로 활용한다면 각 구간별로 수체에 대한 흐름과 유속들을 분석할 수 있을 것으로 사료된다. 또한 GPS 전자부자를 좀더 활용하여 IoT 기반 수질센서 등과 같은 각종 센서가 GPS Floater에 결합이 된다면, 흘러가면서 각종 데이터 정보취득을 통해 수체내 흐름을 분석하는 것뿐만 아니라 수환경 유출오염사고들에 대한 초기대응에 많은 도움이 될 것으로 사료 된다.

• Spatial Information Research
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• v.18 no.4
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• pp.33-41
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• 2010

Approximately 100 permanent GPS stations are currently operational in Korea. However, only 10 sites have their own weather sensors connected directly to the GPS receiver. Thus. calculation of meteorological data through interpolation of AWS data are needed to determine precipitable water vapors at a specific GPS station without a meteorological sensor. This study analyzed the accuracy of two meteorological data interpolation methods called reverse sea level correction and kriging. As a result, the root-mean square-error of reverse sea level correction were seven times more accurate in pressure and twice more accurate in temperature than the kriging method. For the analysis of PWV accuracy, we calculated GPS PWV during the summer season in :2008 by using GPS observation data and interpolated meteorological data by reverse sea level correction. And, we compared GPS PWV s based on interpolated meteorological data with those from radiosonde observations and GPS PWV s based on onsite GPS meteorological sensor measurements. As a result, the accuracy of GPS PWV s from our interpolated meteorological data was within the required operational accuracy of 3mm.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.1
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• pp.97-104
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• 2012

In this paper, the GPS precipitable water vapor was retrieved by estimating of GPS signal delay in the troposphere during the progress of heavy snowfall on the Gangwon Province, 2011. For this period, the time series analysis between GPS precipitable water vapor and fresh snow depth was accomplished. The time series and the comparison with the GPS precipitable water vapor and the fresh snow depth indicates that the temporal change of two variations is closely related to the progress of the heavy snowfall. Also, the periodicity of GPS precipitable water vapor using the wavelet transform method was showed a similar cycle of saturated water vapor pressure as the limitation of this study span. The result shows that the decrement of GPS precipitable water vapor was conflicted with the increment of fresh snow depth at two sites, Gangneung and Uljin. The correlation between the GPS precipitable water vapor and the saturated water vapor pressure for the event was showed a positive correlation, compare with the non-heavy snowfall periods.