• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.1
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• pp.40-47
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• 2013

By virtue of Rec. ITU-R P.1546 and geography information system, interference analysis for the fixed wireless system and radar has been presented based upon the frequency-distance rules with minimum coupling loss, and a comprehensive methodology for assessing interoperability between systems was examined in terms of received signal, protection ratio, frequency dependent rejection. Also to find the antenna gain from a discrimination angle, a useful S-I plane was introduced based on signal and interference vectors derived from the real map with geographic information. To show some computational results, geography information on the map was taken for the given area, and field strength and path profile were illustrated for the radar and fixed wireless system operating at 2.7 GHz, for convenience. In addition the interference effect of receiver was also checked as a function of radar beam direction including protection ratio and frequency dependent rejection. The developed interference analysis can be actually applied to evaluate interoperability for wireless systems in the VHF and UHF bands.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.63-72
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• 2018

Theoretical modelling and computational results for frequency coordination are presented based upon minimum coupling loss regarding the same or different wireless systems. Essential parameters involved in frequency coordination are discussed in view of system characteristics, propagation model, availability and protection ratio, frequency dependent rejection or adjacent channel interference ratio, discrimination angle, and its computational results are also evaluated. To illustrate frequency coordination procedure, received interference power between fixed wireless system of victim and mobile base station of interferer are analyzed in urban or sub-urban area and also compared with maximum allowable interference power as functions of discrimination angle and distance for assumed system parameters. The proposed method will play a practical role in technical analysis on co-existence or interoperability for the various wireless systems needed for frequency coordination.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.6
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• pp.41-49
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• 2017

Theoretical modelling and computational results for frequency coordination are presented over mobile base station and fixed wireless systems in urban or sub-urban area. Computational results with key parameters needed for interference analysis are performed and discussed in terms of system characteristics, propagation model, protection ratio, frequency dependent rejection, and discrimination angle with signal-interference plane. Based upon minimum coupling loss methodology, calculated interference powers of victim receiver for assumed system parameters are compared with maximum allowable interference power derived from protection ratio as functions of discrimination angle and distance including height-gain model in urban or sub-urban area. The proposed method is applicable for technical analysis on co-existence or interoperability for the various wireless systems, mandatory for frequency coordination or reallocation process.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1413-1415
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• 2004

This paper proposes a SVM(Support Vector Machine) training algorithm to control a service robot with voice command. The service robot with a stereo vision system and dual manipulators of four degrees of freedom implements a User-Dependent Voice Control System. The training of SVM algorithm that is one of the statistical learning theories leads to a QP(quadratic programming) problem. In this paper, we present an efficient SVM speech recognition scheme especially based on less learning data comparing with conventional approaches. SVM discriminator decides rejection or acceptance of user's extracted voice features by the MFCC(Mel Frequency Cepstrum Coefficient). Among several SVM kernels, the exponential RBF function gives the best classification and the accurate user recognition. The numerical simulation and the experiment verified the usefulness of the proposed algorithm.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.9
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• pp.417-422
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• 2002

ZnO thin films were deposited on various substrates, such as Si-(111), SiO$_2$(5000 $\AA$ by thermal CVD)/Si-(100), and SiO$_2$(2000 $\AA$ by RF sputtering)/Si-(100). The (002)-orientation, surface morphology and roughness, and electrical resistivity of deposited films were measured and compared in terms of substrate. Surface acoustic wave(SAW) filters with a multilayered configuration of IDT/ZnO/SiO$_2$/Si were also fabricated and the IDT was obtained using a lift-off method. From the frequency-response characteristics of fabricated devices, the insertion loss and side-lobe rejection were estimated. The experimental results showed that the (002)-oriented growth nature of ZnO films, which played a crucial role of determining the characteristic of SAW device, was strong1y dependent upon the SiO$_2$buffer.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.4
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• pp.41-54
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• 2002

In this study, we have analyzed the effects of the membrane layer and the bragg reflector layers on the resonance characteristics through comparing the characteristics of the membrane type FBAR (Film Bulk Acoustic Wave Resonator) and the one type bragg reflector layers with those of the ideal FBAR with top and bottom electrode contacting air by using equivalent circuit technique. It is assumed that ZnO is used for piezoelectric film, $SiO_2$ are used for membrane layer and low acoustic impedance layer, W are used for the high acoustic reflector layer and Al is used for the electrode. Each layer is considered to have a acoustic propagation loss. ABCD parameters are picked out and input impedance is calculated by converting 1-port equivalent circuit to simplified equivalent circuit that ABCD parameters are picked out possible. From the variation of resonance frequency due to the change of thickness of electrode layers, reflector layers and membrane layer it is confirmed that membrane layer and the reflector layer just under the electrode have the greatest effect on the variation of resonance frequency. From the variation of resonance properties, K and electrical Q with the number of layers, K is not much affected by the number of layers but electrical Q increases with the number of layers when the number of layers is less than seven. The electrical Q is saturated when the number of layers is large than six. The electrical Q is dependent of mechanical Q of reflector layers and membrane layer. Both ladder filter and SCF (Stacked Crystal Filters) show higher insertion loss and out-of-band rejection with the increase of the number of resonators. The insertion loss decreases with the increase of the number of reflector layers but the bandwidth is not much affected by the number of reflector layers. Ladder Filter and SCF with membrane layer show the spurious response due to spurious resonance properties. Ladder filter shows better skirt-selectivity characteristics in bandwidth but SCF shows better characteristics in insertion loss.