• Journal of Environmental Science International
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• v.25 no.2
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• pp.267-280
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• 2016

Ground echo is radar return from stationary targets such as buildings and trees. Wind vectors from the wind profile radar in Gangneung are affected by ground echoes due to the complex mountainous terrain located to the west and the south. These ground echoes make a spurious peak close to the direct current (DC) line signal in Doppler spectra. Wind vectors polluted by ground clutters were determined from spectra of oblique beams. After eliminated the terrain echoes, the accuracy of wind vector compared with radiosonde was improved about 68.4% and its relative coefficient was increased from 0.58 to 0.97.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2025-2035
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• 2014

The read range of UHF mobile readers can be extended by a booster for mobile RFID readers (BoMR). But in an environment where multiple BoMRs are installed, the read success rate may be decreased due to signal interference. This paper proposes three arbitration methods based on interference estimation with the purpose of enhancing the read success rate. A central arbitration server manages global information in centralized arbitration method (CAM) without broadcast/multicast communication facility. In fully distributed arbitration method (FDAM), all the arbitration messages are broadcasted from a BoMR to every BoMR, and each BoMR decides with broadcasted global information. Events in FDAM are serialized naturally with broadcasted messages. Cluster Distributed Arbitration Method (CDAM) forms clusters with multicasted BoMRs and a selected BoMR acts as an arbiter in the cluster. Such effects as lengthened read range, improved the read success rates of readers can be obtained by the proposed methods without any hardware modification. In order to evaluate the arbitration methods, the RFID system is modeled by using the DEVS formalism and simulated by using the DEVSim++.

• Proceedings of the Korea Contents Association Conference
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• 2004.11a
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• pp.377-383
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• 2004

In this paper, we propose an application model of RFID that needs not be worried about battery degradation problems and offers convenience of hand-carry. We design the RFID application model which can track medium distance target RFID Tag and detect the signal difference between multi-detectors in a room area using 900MHz frequency band. In the case of multi-ID Tag in one detector, we approach TDMA scheme.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.4
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• pp.564-581
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• 1999

This paper introduces a new, small, low cost, robust and quick replaceable pavement-based vehicle detector using CW radar, magnetometer, and UHF small antennal techniques. The detector has been developed for a replacement of loop detectors having wide surface areas, for a more accurate operation under all weather conditions, and for no algorithmic change of the existing traffic information system. The detected vehicle information is sent by a small helical antenna embedded in a plastic material and received by a 5/8 $\lambda$ long GP antenna for signal processing. In a relatively good weather condition, the detector operates at 24 GHz. But in a heavy rain condition, magnetometer is activated by automatic switching.

• The Journal of the Korea institute of electronic communication sciences
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• v.1 no.1
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• pp.8-19
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• 2006

The RF Module which can be adjusted for a digital terrestrial and multi standard(DVB-C, ISDB-T, DVB-H) reception is developed. The Module by single conversion does divide a broadband(45MHz~860MHz) broadcasting channels into three-bands(UHF, VHF_HIGH, VHF_LOW) to satisfy some electrical performances such as image signal rejection, phase noise, IF flatness etc and digital reception specifications such as analog and digital adjacent channel protection, co-channel protection which is important in environment with co-existence both analog and digital broadcasting systems.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.2 s.58
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• pp.61-70
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• 2006

In this paper, we compare the performance of representative MIMO techniques such as space-time block code, closed-loop transmit diversity, and V-BLAST, etc., in IEEE 802.22 environments. We first develope deco-ding algorithms of the representative MIMO techniques and design a MIMO-OFDM system employing QPSK, 16 QAM, 64 QAM to cover several transmission rates. Since the frequency band used for IEEE 802.22 systems belongs mostly to V/UHF band and the angular spread of the received signal at the base station is very small, there Is a significant correlation between the signals from transmit antennas. Thus, in this paper, we compare the performance of MIMO-OFDM systems employing only two Tx antennas in correlated fading environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.345-355
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• 2006

The RF Module which can be adjusted for a digital terrestrial and multi standard(DVB-C, ISDB-T, DVB-H) reception is developed. The Module by single conversion does divide a broadband($45MHz{\sim}860MHz$) broadcasting channels into three-bands(UHF, VHF_HIGH, VHF_LOW) to satisfy some electrical performances such as image signal rejection, phase noise, IF flatness etc and digital reception specifications such as analog and digital adjacent channel protection, co-channel protection which is important in environment with co-existence both analog and digital broadcasting systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.490-499
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• 2006

In this paper, we present the newly developed propagation toss model of a long range maritime communication channel, measured by a ground to air flight test, and discuss its validity compared with the predictive value based on the spherical earth reflection model. To measure the propagation loss, actual flight test was performed in the Yellow Sea and the measurement of receiving signal strength was made for overall test range. As far as the test condition is concerned, it is expected that the receiving signal strength must be interfered with the reflected wave by an island existing around the reflection point. Therefore we introduce some modifications on the conventional spherical earth reflection model by including the effect due to the reflected wave from the island. And then, we compare the path loss measured by flight test with that one analyzed by the spherical earth reflection model accounting for reflected wave of the island. As a result of the comparison, it is verified to predict the path loss accurately by the spherical earth reflection model including the effect due to the reflected wave from an island for a long range ground to air communication.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.12 s.115
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• pp.1212-1223
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• 2006

Microwave(M/W) bands, though having great demand in wireless services, have been used mostly for long distance communications. As a result, the studies on their mobile radio models have been made less than on VHF/UHF. However, as the mobile communication services with M/W bands have been increasing, the development of a more accurate prediction model of the mobile radio environments has been demanded. The development of a reliable radio prediction model in the mobile radio environments requires the measurement and analysis of the characteristics of the radio waves according to reflection, diffraction and scattering of radio signals in various mobile radio environments. The proposed 8 GHz band radio prediction models have 2 different categories: (1) LOS model and (2) non-LOS model. The LOS model predicts signal strength using the analytic result with measured pathless exponents for the waves direct and reflected by ground and buildings, and the non-LOS model suggests a prediction model of received power by calculating the signal variations after diffraction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1616-1626
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• 2010

This paper will show how self-alarming EAS(Electronic Article Surveillance) system can improve its receiving performance of magnetic field signal and reduce false alarm using dual-band wireless communication. Our research improved the receiving performance and the areas of recognition of magnetic signal through the change of VLF receiving circuit and alarm transmitting method. In addition, we verified the reduction of false alarm by improvement of integrity and distance between tag and receiver through experiment. Thanks to our research, we can build the high performance and economical EAS with low false alarm on the multi gate store.