• The Journal of the Acoustical Society of Korea
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• v.24 no.2E
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• pp.61-66
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• 2005

Experimental work in underwater acoustic communications using passive phase conjugation has shown that the demodulation error depends on the relative drift rate between the source and receiver [Rouseff et al., IEEE J. Oceanic Eng. 26, 821-831 (2001)]. The observed effect involves the mismatch between the initial impulse response and the subsequent response after the source or receiver has changed locations. In the present work, the effect of drifting source is analyzed by numerical simulations and compared to the experimental results. The communications bit error rate is qualified as a function of drift rate, drifting direction, and source-receiver range.

• Journal of Power Electronics
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• v.13 no.4
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• pp.669-678
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• 2013

This paper proposes a sensorless control approach for Wound Rotor Synchronous Machines (WRSMs) based on a high frequency voltage signal injection into the stator side U phase and VW line, respectively. Considering the machine itself as a rotor position sensor, the rotor position observer is established according to the principles of the rotary transformer. A demodulation method for the high frequency signal inducted in the rotor is proposed as well. Simulation and experimental results show that the proposed sensorless control approach has high performance and good practicability.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.9-12
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• 2001

In DS/CDMA system the number of output signal levels increases as multi-channel signals are summed, hence the power amplifier with high linearity is required. PW/CDMA is a transmission technique that performs pulse width modulation on the multilevel signal synthesized from multiple channel data. In PW/CDMA system the signal level is maintained to be binary, hence the modulation and demodulation circuits become simple. In this paper we derive the probability of bit error of the PW/CDMA system in AWGN environment. The results are compared with DS/CDMA system and are verified through the computer simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.1016-1021
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• 1999

In order to obtain a demodulated signal from RZ-SSB signal, it is important to design a linearizer which cancels the high-order distortions after FM demodulation. Since the NTT's linearizer must include a Hilbert transform, the characteristics of the linearizer are determined by the characteristics of Hilbert transform and it is very complicated to design and realize especially in the low frequency range. In the case of the proposed linearizer, the high-order distortion can be reduced without using any Hilbert transform. Furthemore, unlike the conventional RZ-SSB Demodulator, the proposed linearizer can be realized easily.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6C
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• pp.506-515
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• 2010

In this paper, we compare and analyze the spectral efficiency of representative adaptive MIMO algorithms in indoor environments. We first briefly investigate the modulation and demodulation schemes of MIMO algorithms to be compared and then implement adaptive algorithms by using BPSK and square QAM schemes up to 256QAM. We finally compare the spectral efficiency of adaptive MIMO algorithms employing (2$\times$2) or (4$\times$4) antenna array through the computer simulation in indoor environments.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.6
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• pp.272-277
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• 2002

This paper deals with the vibration deflection shape measurement technique for a sinusoidally excited structure using a continuously scanning laser Doppler vibrometer (CSLV). The CSLV output signal is an amplitude-modulated vibration in which the excitation signal is modulated by the deflection shapes, and thus the deflection shapes of vibration defined along a scan line can be derived by the envelop and the phase information of the CSLV output signal. In this work, a Hilbert transform based approach has been proposed for measurement of deflection shapes. This technique is as simple as the demodulation technique and allows more convenient experimental settings than the Fourier transform approach. The feasibility of the proposed technique is illustrated along with results of experiment.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.308-311
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• 2004

This paper describes design, implementation and functional test of on-board flight analog video system. Video system is the part of the telemetry system as a means of providing flight vehicle's image data. Adopting analog video transmission technique, we could design and test the system in a short time and implement the prototype model with simpler circuits. As results of the functional test, we have made the verification and validation of two cameras' switching in time, and frequency modulation and demodulation of NTSC color signals successfully.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.414-419
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• 2003

There are some methods fur extracting mode shapes from a continuously scanned data such as a modulation, Chebyshev polynomial, and Hilbert approach. In this paper, Chebyshev and Hilbert approaches were investigated through the numerical experiment first. As some experimental parameters were altered with small quantities, data were checked and plotted. From those results, the effects of unexpected parameters will be configured. And then, it will be actually helpful to select the proper method for specific testing environments.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.649-650
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• 2006

An analysis is made of a new 1Gbps MB-OFDM system having same bandwidth and transmission power as conventional 480Mbps system. $2{\times}2$ MIMO scheme and MLD with soft decision demodulation algorithm are proposed in this paper. As a result of hardware implementation, it showed as same performance as conventional MB-OFDM system, while presenting doubled data rates and low complexity.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.903-907
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• 2002

A hyper-chaos circuit is created by applying identical n-double scrolls with weak coupled method, to each cell. Hyper-chaos synchronization was achieved using dive response synchronization between the transmitter and receiver about each state variable in the SC-CNN. From result of the recovery signal through the demodulation method in the receiver, We shown that recovery quality of state variable $\chi$$_3$ is superior to that of $\chi$$_2$,$\chi$$_1$in secure communication.