• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.4
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• pp.319-326
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• 2006

To get the highly-accurate and precise position of a GPS receiver, they should consider the state-of-the-art GPS force and measurement models. Especially, the phase center variations (PCV) of a GPS antenna can cause several centimeters of positioning errors in the vertical direction. In this study, we implemented four different models of PCV and evaluated their impact on the computed coordinates. The test data were taken from the 14 National Geography Information Institute permanent GPS stations and 30 Minisry of Government Administration and Home Affairs sites. For different combinations of calibration methods, an average of 1.3-2.6cm of height difference was observed. Also, we found a maximum error of ${\sim}4mm$ in the estimates of the precipitable water vapors.

• Journal of Korea Society of Digital Industry and Information Management
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• v.15 no.4
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• pp.85-92
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• 2019

This paper presents a SDR-based Long Term Evolution Advanced (LTE-A) Physical Downlink Shared Channel (PDSCH) decoder using a multicore Digital Signal Processor (DSP). For decoder implementation, multicore DSP TMS320C6670 is used, which provides various hardware accelerators such as turbo decoder, fast Fourier transformer and Bit Rate Coprocessors. The TMS320C6670 is a DSP specialized in implementing base station platforms and is not an optimized platform for implementing mobile terminal platform. Accordingly, in this paper, the hardware accelerator was changed to the terminal implementation to implement the LTE-A PDSCH decoder supporting the multi-antenna and the functions not provided by the hardware accelerator were implemented through core programming. Also pipeline using multicore was implemented to meet the transmission time interval. To confirm the feasibility of the proposed implementation, we verified the real-time decoding capability of the PDSCH decoder implemented using the LTE-A Reference Measurement Channel (RMC) waveform about transmission mode 2 and 3.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.755-762
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• 2000

In this work, we present the resonant frequencies, Qrad, and impedance bandwidth of rectangular dielectric resonator antenna(DRA)for a broad range of aspect ratios using Dielectric Waveguide Model. These presented data are compared with simulation and measurement. The DRA having relative permittivities of 37.84 and 90 have been fed by a coaxial cable and fed using a aperture-coupled method for comparisions. The approximate resonant frequencies are shown to have the prediction error of about 8% and impedance bandwidth is found to have large prediction variation according to feeding method. The data presented in this paper can be used when the aspect ratios of DRA have to be determined for a given resonant frequency and impedance bandwidth.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.6
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• pp.602-612
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• 1997

With GPS carrier phase measurements from more than two antenna which attached to the vehicle, precise attitude can be easily obtained if the integer ambiguity included in carrier phase measurement is resolved. Recently some special products which use dual frequencies or has one receiver engine with multiple antenna are announced. But there are still strong requirements for the conventional single frequency off-the-shelf receiver. To meet these requirements, an efficient integer ambiguity resolution technique is indispensable. In this paper, a new technique to resolve integer imbiguity with single frequency receivers is proposed. The proposed method utilize the known baseline length as a constraint of independent elements of integer ambiguities. With this constraints, the size of search volume can be greatly reduced. Thus the true integer ambiguity can be easily determined with less computational burden and number of measurements. The proposed method is applied to real data to show its effectiveness.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.1
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• pp.44-49
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• 2001

In this paper, we propose a new technique to compensate for the VCO nonlinearity using only the returned beat signal whose spectrum contains the internal reflections and the targets simultaneously. In the case of a distance measurement system using single antenna, the reflections from the circulator and the antenna are much larger than the return signal from target. The beat signal by these reflections is at much lower frequency than that of the target, and the VCO nonlinearity can be compensated for using these signals. Indoor experiments were carried out and the results show marked improvement in the shape of range profile and the range resolution.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.931-936
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• 2018

We designed an x-band radar for motion detector using a frequency tunable hairpin ring resonator. The proposed doppler radar sensor can vary the oscillation frequency by applying a hairpin resonator using a varactor diode to the oscillator, and this can also reduce the size by transmitting and receiving a signal from Tx/Rx dual antenna. The fabricated doppler radar sensor was fabricated in $30{\times}24mm$, and it was confirmed that the pulse width difference occurred according to the distance from the object. The measurement results showed oscillation at 10.525GHz. We confirmed that it is enough to use as radar for motion detection from the measured results.

• Journal of Electrical Engineering and Technology
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• v.2 no.1
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• pp.123-128
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• 2007

SPWPM traditional software development is surveyed and essential problems are investigated on the basis of system wireless link considerations. This paper presents the current state software planning tools for wireless LAN link optimization. The software directory is based on combination of MatLab and MapInfo software and measurement which gives the best grouping parameters to build up the software development. Among the requirements assumed, the WLAN site selections must be Line-of-sight (LOS) or near line of sight (NLOS) field strength prediction for either point to point or point to multi points. The results obtainable the out put of the program include two-dimensional (2D) and three dimensional (3D) plots for creating the link; design parameters through GUI representing the height and location for each antenna is depending on K-factor of the area and transmit antenna location.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.899-910
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• 2013

This paper presents a novel lateral stability control system for electric vehicle based on sideslip angle estimation through Kalman filter using the integration of a single antenna GPS receiver and yaw rate sensor. Using multi-rate measurements including yaw rate and course angle, time-varying parameters disappear from the measurement equation of the proposed Kalman filter. Accurate sideslip angle estimation is achieved by treating the combination of model uncertainties and external disturbances as extended states. Active front steering and direct yaw moment are integrated to manipulate sideslip angle and yaw rate of the vehicle. Instead of decoupling control design method, a new control scheme, "two-input two-output controller", is proposed. The extended states are utilized for disturbance rejection that improves the robustness of lateral stability control system. The effectiveness of the proposed methods is verified by computer simulations and experiments.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.505-506
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• 2006

PD(partial discharge) occurred from variable PD sources in air may be the cause of breakdown in high voltage equipment which affect huge outage in power system. Identification and localization of PD sources is very important for engineer to cope with huge accident beforhand. PD phenomena can be detected by acoustic emission sensor or electromagnetic sensor like antenna. This paper has investigated the identification method using PCA(principal component analysis) for the PD signals from variable PD sources, for which the electric field distribution and PD inception voltages were simulated by using commercial FEM program. PD signals was detected by ultra wideband antenna. Their own features were extracted as the frequency coefficients transformed with FFT(fast fourier transform) and used to obtain independent pincipal components of each PD signals.

• ETRI Journal
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• v.42 no.6
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• pp.837-845
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• 2020

The objective of this study was to implement an in vitro exposure system for 28 GHz to investigate the biological effects of fifth-generation (5G) communication. A signal source of 28 GHz for 5G millimeter-wave (MMW) deployment was developed, followed by a variable attenuator for antenna input power control. A power amplifier was also customized to ensure a maximum output power of 10 W for high-power 28-GHz exposure. A 3-dB uniformity over the 80 mm × 80 mm area that corresponds to four Petri dishes of three-dimensional cell cultures can be obtained using a customized choke-ring-type antenna. An infrared camera is employed for temperature regulation during exposure by adjusting the airflow cooling rate via real-time feedback to the incubator. The reported measurement results confirm that the input power control, uniformity, and temperature regulation for 28-GHz exposure were successfully accomplished, indicating the possibility of a wide application of the implemented in vitro exposure system in the fields of various MMW dose-response studies.