• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.33-38
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• 2003

We automated high-accuracy data processing routines for various near-real-time GPS applications. The automated system was based on UNIX, and it uses GIPSY-OASIS II and ultra-rapid orbits which is updated twice a day and provided online. The highest error in the estimated site position was 2 cm and 5 cm in the horizontal and vertical directions, respectively. The mean 3-D position error about 2 cm.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.183-195
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• 2004

Photogrammetry is one of the most important sources of GIS application. Nowadays, color photos are used and camera is integrated with GPS/INS sensors. However the photos are still taken from analogue camera and scanned for digital image. For the convenient and accurate image application especially for 3D, airborne digital camera images is essential. In this paper, digital image calibration process with GPS/INS and its accuracy evaluation was presented.

• Electronics and Telecommunications Trends
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• v.8 no.2
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• pp.53-59
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• 1993

발진기의 특정시간 동안의 주파수 안정도 측정을 위하여 시간영역에서의 측정방법인 알랜분산(Allan Variance)을 응용하였으며, 기준 주파수는 GPS 위성으로부터 세계시를 수신하여 이용하였다. 또한 측정시스팀의 자동제어 및 측정 데이터의 처리를 위한 S/W를 개발하여 GPS를 이용한 주파수 안정도 측정시스팀을 개발하였다.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.12 no.2
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• pp.83-94
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• 2004

In this overview of RNAV(Area Navigation) covers the general notion of air navigation, the general concept of RNAV and Navigational facilities or elements to achieve RNAV. also, this overview includes RNAV operations on instrument approaches with GPS, VNAV(Vertical Navigation) operations and the future of RNAV.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.183-186
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• 2002

In this paper, a microstrip Patch antenna with the T-shaped slits, which are employed to reduce the patch size. is proposed for GPS In order to analyze characteristics of the antennas are defined green function of the moment method. The microstrip Patch antenna and microstrip Patch with the T-shaped slits are fabricated. The numerical result of return loss and -10d13 bandwidth are compared with measured results.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.4
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• pp.397-405
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• 2008

The position accuracy is primarily dependent on the satellite position and signal delay caused by several elements. To know the effect of the delay on the estimated positions, we simulated GPS raw data (RINEX) with GPS errors using Bernese ver5.0. GPS errors used in this paper are Ionospheric delay, Cycle slip, Troposphere, DOP and Random error. If the baseline is short, the position error according to TEC is not large, since the ionospheric delay effect can be removed by ion-free combination. However, if the baseline is long, 3 dimensional position error up to 10cm is occurred. The 3D position error of coordinates with cycle slip is hardly ever changed up to 60% of cycle slip. Because the simulated cycle slips are equally distributed on satellites, the positioning was not seriously affected by the cycle slip. Also, if percentage of cycle slip is 60%, three dimensional error is sharply increased over 1m. The position error is calculated by using the observation data (2 hours) which was selected by DOP less than 3. And its accuracy is more improved about $3{\sim}4cm$.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.64-68
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• 2007

This paper describes the development of RF front.end equipment of a wide band high precision satellite navigation receiver to be able to receive the currently available GPS navigation signal and the GALILEO navigation signal to be developed in Europe in the near future. The wide band satellite navigation receiver with high precision performance is composed of L - band antenna, RF/IF converters for multi - band navigation signals, and high performance baseband processor. The L - band satellite navigation antenna is able to be received the signals in the range from 1.1 GHz to 1.6 GHz and from the navigation satellite positioned near the horizon. The navigation signal of GALILEO navigation satellite consists of L1, E5, and E6 band with signal bandwidth more than 20 MHz which is wider than GPS signal. Due to the wide band navigation signal, the IF frequency and signal processing speed should be increased. The RF/IF converter has been designed with the single stage downconversion structure, and the IF frequency of 140 MHz has been derived from considering the maximum signal bandwidth and the sampling frequency of 112 MHz to be used in ADC circuit. The final output of RF/IF converter is a digital IF signal which is generated from signal processing of the AD converter from the IF signal. The developed RF front - end has the C/N0 performance over 40dB - Hz for the - 130dBm input signal power and includes the automatic gain control circuits to provide the dynamic range over 40dB.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.2
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• pp.50-55
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• 2008

In this paper, multi-band internal antenna which can adjust both resonant frequency and input impedance of antenna as using lumped inductor between shoring plate and ground plane is proposed. The structure of proposed antenna consists of PIFA (Planar Inverted F Antenna) structure and half-wavelength loaded line structure and has two shorting plates and one feeding plate. One shorting plate is shared. The operating frequency bands of designed antenna are GSM, GPS in the PIFA structure and DCS, US-PCS, W-CDMA in half-wave loaded line structure as varying the inductor value in 2.2nH, 3.3nH, and 4.7nH. As varying the inductor value in the shared shorting plate, input impedance of antenna is varied. To minimize the gain variation of antenna as adding lumped element, the inductor value is restricted at maximum of 6.8nH. The maximum gain of proposed antenna is measured as -1.60dBi in the GSM band, -1.16dBi in the GPS band, and 1.41dBi in the DCS/US-PCS/W-CDMA band.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.1
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• pp.743-750
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• 2009

Since aerial photogrammetry by analog camera began in 1972, recently, high resolution digital camera is actively introduced to improve efficiency of aerial photogrammetry. This study investigated the 3D positioning accuracy of DMC(Digital Mapping Camera) among various high resolution aerial digital cameras to be developed for photogrammetry. For the research, we installed control points in test field around Incheon, and acquired analog and digital aerial photographs. By comparing 3D positioning accuracies of analog and digital photographs, there are few difference between two cameras, and the 3D positioning accuracies of two cameras was somewhat increased in case of aerotriangulation using additional control points based on GPS/IMU EO data.

• Journal of electromagnetic engineering and science
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• v.13 no.1
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• pp.44-50
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• 2013

In this paper, we present a circularly polarized (CP) composite cavity-backed crossed dipole antenna for global positioning system (GPS) applications. We produce the CP radiation by crossing two dipoles through a $90^{\circ}$ phase delay line of a vacant-quarter printed ring, which also has a broadband impedance matching characteristic. Two techniques, insertion of meander lines in the dipole arm and arrowhead-shaped trace at its end, are employed to reduce the sizes of the primary radiation element. The compact radiator is backed by a cavity reflector to achieve a wide CP radiation beamwidth. The proposed antenna exhibits a measured bandwidth of 1.450~1.656 GHz for a voltage standing wave ratio (VSWR) < 2 and 1.555~1.605 GHz for AR < 3-dB. At 1.575 GHz, the antenna has a gain of 7 dBic, a frontto-back ratio of 27 dB, AR of 1.18 dB, and 3-dB AR beamwidths of $130^{\circ}$ and $132^{\circ}$ in the x-z and y-z planes, respectively.