• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.3
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• pp.61-69
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• 2018

In this paper, we propose a method for recognizing ground target using dual polarization channels in millimeter waveband air-to-surface radar. First, the Push-Broom target detection method is described and the received signal is modeled considering flight-path scenario of air-to-surface radar. The scattering centers were extracted using the RELAX algorithm, which is a time domain spectral estimation technique, and the feature vector of the target was generated. Based on this, a DB for 4 targets is constructed. As a result of the proposed method, it is confirmed that the target classification rates is improved by more than 15% than the single channel using the data of the dual polarization channel.

• Journal of IKEEE
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• v.7 no.1 s.12
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• pp.16-21
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• 2003

A rigorous modal transmission-line theory (MTLT) based on effective dielectric method (EDM) is introduced and developed to analyze the polarization beam-splitting of optical rib-type directional coupler with three guiding layers. Furthermore, to confirm the validity of approach proposed in this paper, we compare our results with those ones of BeamPROP, which is a commercial software package used widely. Consequently, the numerical results reveal that the hybrid modes incident into a guiding channel of rib-type coupler are split well through upper and lower guiding channels in a polarization length.

• Journal of the Korea Society of Computer and Information
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• v.13 no.1
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• pp.135-141
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• 2008

The utilization techniques for multiple transmit and receive antennas or high capacity modulation schemes are essential to cope with the rapidly increasing demand for realizing more diverse wireless communication services with high rates. However, employing multiple receive antennas at the mobile units seems less practical due at the size and power limitations. Therefore, transmit diversify techniques have been extensively investigated for the downlink transmission to improve the performance In order to overcome the above mentioned problems, we construct a simulation model which combines STC and polarization diversity which scheme is requiring less cost to realize. Multi-level quadrature amplitude modulation (MQAM) is an attractive modulation scheme for wireless communication due to the high spectral efficiency it provides. Thus, the performance for our scheme is presented when 16QAM modulation techniques are applied. and compared with the former schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.114-124
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• 2002

In this paper, we proposed the image-based 3D ray tracing indoor propagation model using a patch scattering model for fading analysis of indoor propagation environments. An image-based 3D ray tracing technique is mainly used, which allows the rapid generation of the complex channel impulse response for any given location and polarization of transmitter and receiver. Due to the site specific nature of indoor environment, we took into account the location and the electrical properties of individual walls and objects such as windows, doors and plaster board in our propagation model. Besides, the 3D radiation beam-patterns and polarizations of arbitrary antennas were considered, and using patch scattering model we can consider the change of the polarization due to the scattering from the various indoor objects, like desks, chairs and etc. the are almost impossible to be modeled with the basic image-based ray tracing method. The model will predict the impulse response, the rms delay spread, the fading characteristics of the channel and performances of the polarization diversity schemes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.5
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• pp.463-470
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• 2016

In this paper, we introduce a method of scattering centers extraction using the polarimetric data. VIRAF software based on the PO (Physical Optics) and PTD(Physical Theory of Diffraction) were used to calculate the surface scattering and the edge or wedge scattering, respectively. In addition, by using the unitary transformation, 4-channel data based on the linear polarization basis were converted to 2-channel data based on the left/vertical-circular polarization basis, leading to data compression coherently. The scattering mechanism was analyzed in terms of the polarization states and different look angles by using the scattering center of a target extracted by the 2D RELAX algorithm.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.186-192
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• 2005

A numerical study on the performance of a PEMFC was performed by using a CFD-ACE+commercial program. The effects of width, hight and shape of channel cross section and mass flow rate were investigated. In order to check the validity of the simulation, comparisons were carried out between predictions and experimental data available in the literature and shows the reasonable agreement. It is found that only the width of channel is strongly related to the performance of a PEMFC, while other factors have no marked effects.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.215-216
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• 2006

In this paper, the antenna the with linear active phased array of $1{\times}16$ operated in DBS band was designed. The antenna was composed of sixteen radiating elements, sixteen active channels and five Wilkinson power combiners with 4-channel inputs, a digital control board and a stabilizing DC bias board. The radiating element of the array has the structure of a microstrip stack patch with a left-hand circular polarization. And, each active channel consists of a low noise ampilifier, a 3-bit digital phase shifter and a variable analog attenuator. The breadboard of linear active phased array antenna was also fabricated to test the electrical performances. The radiation patterns of the antenna were measured after correcting initial phases of each active channel in aechoic chamber. And also, the beam scanning chracteristcs of $10^{\circ}$, $20^{\circ}$, $30^{\circ}$ were measured.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.8
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• pp.759-764
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• 2004

This paper proposes a method that estimates MIMO channel characteristics analytically using a 3D ray tracing propagation model. We calculate the discrete spatial correlation between sub-channels by considering phase differences of paths, and using this, estimate the mean capacity upper bound of MIMO channel by Jensen's inequality. This analysis model is a deterministic model that do not approach stochastically through measurement nor approach statistically through Monte-Carlo simulations, so this model has high efficiency for time and cost. And based on the electromagnetic theory, this model may analyze quantitatively the parameters which can affect the channel capacity - antenna pattern, polarization mutual coupling, antenna structure and etc. This model may be used for the development of an optimal antenna structure for MIMO systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8B
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• pp.809-818
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• 2002

In this paper, we propose a fast cell search algorithm keeping compatible with the standard cell search algorithm of the WCDMA system. The proposed algorithm can acquire the synchronization of slot and frame times, and the code group identification using only one synchronization channel while the standard algorithm employs two synchronization channels called P-SCH and S-SCH. The proposed synchronization channel structure is the same as the P-SCH structure of the WCDMA system. However, the P-SCH is modulated with a specific polarization code, which is one element of new code group codes. The proposed algorithm can reduce both the BS' transmission power and the complexity of receiver as compared with the conventional one since only on synchronization channel is used. It is shown through the computer simulation that the proposed algorithm yields a significant improvement in terms of cell search time compared with the standard especially in low SNR environments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.872-878
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• 2003

In this paper, we developed a simulator which can generate the polarization waves for the indoor wireless communications based on three dimensional ray tracing technique and verified the simulation results comparing with the measured data in indoor wireless propagation environments. Using the developed simulator, we analyzed the channel characteristic and polarization diversity reception characteristic for the vertical, horizontal and circularly polarized waves. From the analysis results, in the case of using circularly polarized wave it can be clearly seen that the multipath fading is markedly reduced compared to the vertical and horizontal polarized waves due to the reception characteristic of removing the odd time reflected waves.