• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2768-2774
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• 2011

In this paper, we investigate the methods to improve the position accuracy using DGNSS(Differential Global Navigation Satellite System). Then we configure the real-time DGNSS environment with use of GPS and MSAS as SBAS(Satellite Based Augmentation System) currently being in service by Japan. And we verify the improvement of position accuracy and the continuity of GPS correction data through the realtime DGNSS test in Joongang line, Kyungbu line, Honam line.

• 대한토목학회논문집
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• 제26권2D호
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• pp.317-324
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• 2006

본 연구는 지적 측량을 목적으로 운용되고 있는 지적위성기준점의 ITRF2000 기준의 절대 좌표 결정을 위한 정밀한 GPS 데이터 해석에 관한 것이다. 제트 추진 연구소에서 개발한 정밀 GPS 데이터 해석 소프트웨어인 Gipsy-Oasis II를 이용하여 궤도와 대기 파라미터를 추정하고 시범 기간 동안의 GPS 상시관측소에 대한 일별 성과를 계산하였다. 특히, 전처리 과정에서 전리층 지연, 대류권 지연, 데이터 부재 여부, 관측 데이터 품질 검사 등을 수행하였다. 본 연구 결과, 절대 좌표는 ${\pm}4mm$ 이하의 높은 정밀도로 결정되었다. 또한, 동 관측소에 대한 기존의 Bernese s/w 해석 결과와 비교한 절대 좌표의 차이에 대한 RMSE는 ${\Delta}X={\pm}0.079m$, ${\Delta}Y={\pm}0.019m$ and ${\Delta}Z={\pm}0.031m$의 차이를 보였다.

• Journal of Communications and Networks
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• 제12권6호
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• pp.592-599
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• 2010

In recent years, significant improvements have been made to the techniques used for analyzing satellite communication and attacking satellite systems. In 2003, a research team at Los Alamos National Laboratory, USA, demonstrated the ease with which civilian global positioning system (GPS) spoofing attacks can be implemented. They fed fake signals to the GPS receiver so that it operates as though it were located at a position different from its actual location. Moreover, Galileo in-orbit validation element A and Compass-M1 civilian codes in all available frequency bands were decoded in 2007 and 2009. These events indicate that cryptography should be used in addition to the coding technique for secure and authenticated satellite communication. In this study, we address this issue by using an authenticated key-exchange protocol to build a secure and authenticated communication channel for satellite communication. Our protocol uses identity-based cryptography. We also prove the security of our protocol in the extended Canetti-Krawczyk model, which is the strongest security model for authenticated key-exchange protocols, under the random oracle assumption and computational Diffie-Hellman assumption. In addition, our protocol helps achieve high efficiency in both communication and computation and thus improve security in satellite communication.

• 한국항공운항학회지
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• 제19권2호
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• pp.23-28
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• 2011

Michibiki is the first QZSS satellite, which was launched by a H-IIA rocket departing from the Tanegshima in Japan on 11 September, 2010 and now operated successfully. This paper presents the results obtained from processing of the L1 C/A signal transmitted from the QZSS satellite. The acquisition and tracking are performed by the L1 software receiver implemented by ETRI. The signal processing results show that QZSS L1 C/A signal is normally processed through the tracking loop results of FLL, PLL, and DLL, the EPL correlator output, and the C/No output. Finally, the paper demonstrates that the QZSS satellite could be used in the navigation system together with the GPS satellite in Korea.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.386-389
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• 2007

Currently, fast and accurate long baseline positioning in kinematic mode is a challenging topic, but positional accuracy can be improved with the help of the network-derived external ionospheric corrections. To provide not only ionospheric corrections, but also their variances, satellite-by-satellite interpolation for the ionospheric delays is performed using the least-squares collocation (LSC) method. Satellite-by-satellite interpolation has the advantage in that the vertical projection used in single-layer ionospheric model is not required. Also, more reliable user positioning and the corresponding accuracy assessment can be obtained by providing not only external ionospheric corrections but also their variances. The rover positioning with and without the external ionospheric delays in both rapid-static and kinematic mode was performed and analyzed. The numerical results indicate that the improvement in the positioning quality is achieved using the proposed method. With the TAMDEF network in Antarctica, 18 % improvement in mean time-to-fix in kinematic mode was achieved.

• 한국항공운항학회지
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• 제16권2호
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• pp.12-20
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• 2008

Japanese MSAS (Multi-functional Satellite Augmentation System) satellites have been transmitting GPS satellite orbit and ionosphere correction information since 2005. MSAS coverage includes Far East Asia, and it can improve the accuracy and integrity of GPS position solutions in Korea. This research analyzed the ionosphere correction information from the MSAS ionosphere correction data. The ionosphere delay data observed by a dual frequency receiver is compared with the MSAS ionosphere correction data. The variation of MSAS GIVE values are analyzed in connection with the equatorial anomaly and ionosphere scintillation.

• Journal of Positioning, Navigation, and Timing
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• 제5권4호
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• pp.165-172
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• 2016

A Global Navigation Satellite System (GNSS), which is typically exemplified by the Global Positioning System (GPS), employs a open signal structure so it is vulnerable to spoofing electronic attack using a similar malicious signal with that used in the GPS. It is necessary to require a spoofing test evaluation environment to check the risk of spoofing attack and evaluate the performance of a newly developed anti-spoofing technique against spoofing attacks. The present paper proposed a simulation method of spoofing environment based on simulator that can be implementable in a test room and analyzed the spoofing simulation performance using commercial GPS receivers. The implemented spoofing simulation system ran synchronized two GPS simulator modules in a single scenario to generate both of spoofing and GPS signals simultaneously. Because the signals are generated in radio frequency, a commercial GPS receiver can be tested using this system. Experimental test shows the availability of this system, and anti-spoofing performance of a commercial GPS receiver has been analyzed.

• 한국군사과학기술학회지
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• 제14권2호
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• pp.232-237
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• 2011

This paper analyzed the J/S of the GPS receiver in sea environment from GPS satellite and GPS jammer. Through the analysis, the operational range and effective radiation power of the GPS jammer could be estimated. In the case of the jammer effective radiation power is higher than the specific value, jammer height mainly resolves the jammer operational range.

• 한국통신학회논문지
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• 제41권12호
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• pp.1756-1758
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• 2016

의사거리는 GPS 수신기의 위치를 결정하기 위한 오차를 포함해 측정된 GPS 위성과 수신기 사이의 거리이다. 재방송 재밍기는 GPS 수신기에 가까이 있을 때 효과적으로 동작한다. 본 논문에서는 재방송 재밍의 원리를 효과적으로 이해하기 위해 근접한 GPS 수신기의 의사거리 차를 분석한다.

• 한국전자통신학회논문지
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• 제13권1호
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• pp.229-236
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• 2018

본 논문에서는 GPS 수신기에서 L1 C/A 신호의 포착과 추적을 이해하고, GPS 수신기 신호의 수신에 관해서 연구하고, GPS 신호 수신과정에 관해서 Matlab을 사용해서 모의실험을 한다. 실험한 결과, 우리가 실행한 방법의 정확성과 가능성을 확인할 수 있었고, GPS 수신기의 성능은 위성의 수신능력이 매우 중요하다는 것을 알 수 있었다.