• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2A
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• pp.91-99
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• 2011

Several repeater systems are used to enhance the cell coverage to location such as shadow and rural areas in mobile systems. But the general RF repeater solutions are not suitable for high power outdoor environment because it has the weakness such as self oscillation problem With adoption of a adaptive digital filter technology, feedback interference cancellation repeater prevents oscillation by detecting and canceling the unwanted feedback signal between transmission and receiver antenna. In this paper, dual NLMS based interference cancellation method is proposed and the step size adaptation can be implemented by the estimation of the feedback channel Doppler frequency characteristics. The performance of the proposed algorithm is quantified via analysis and simulation for the static and multipath fading feedback channels.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.3
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• pp.381-389
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• 2015

A fully integrated multistandard multiband CMOS mobile TV tuner with small silicon area and low power consumption is proposed for receiving multiple mobile digital TV signals and FM signal. In order to reduce the silicon area of the multistandard multiband receiver, other RF front-end circuits except LNAs are shared and a local oscillator (LO) signal generation architecture with a single VCO for a frequency synthesizer is proposed. To reduce the low frequency noise and the power consumption, a vertical NPN BJT is used in an analog baseband circuits. The RF tuner IC is implemented in a $0.18-{\mu}m$ CMOS technology. The RF tuner IC satisfies all specifications for DVB-H/T, T-DMB, and ISDB-T with a sufficient margin and a successful demonstration has been carried out for DVB-H/T, T-DMB, and ISDB-T with a digital demodulator.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.6
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• pp.1032-1035
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• 2008

In this paper, a DC power management scheme is proposed for efficient battery operation of 60-GHz receivers. It consists of a rectenna and a zero-cross detector. The harmonic rejection capability of a circular sector antenna is used to simplify the rectenna. The zero-cross detector is introduced to increase sensitivity. When the received power density is larger than 0.013 $mW/cm^2$, it can generate enough DC power to activate an RF receiver. Experimental data is used to verify the proposed idea.

• Journal of electromagnetic engineering and science
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• v.12 no.4
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• pp.287-289
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• 2012

This paper proposes an alternate time-switched space-frequency block coding transmission technique for orthogonal frequency division modulation systems. There are two antennas in the transmitter but it still has only a baseband and RF and a switch that alternates between the antennas at every symbol timing. Alternating transmit symbols result in zeros that make maximal ratio receive combining possible in the receiver. Simulation results show that it provides better performance than the traditional algorithm at the expense of one additional antenna.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2923-2926
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• 2003

In this paper, a swallowable miniaturized capsule, which applicable for electrical stimulation of digestive organ to improve the motion of intestine in research purpose, is proposed and implemented. The developed capsule can be controlled for the behavior of the power on/off, amplitude and pulse rate for the patient stimulus, by internally equipped with miniaturized RF receiver that linked by the command of external transmitter The experimental result of the implemented miniaturized capsule in the animal intestine show the ability of effective control for the stimulus parameters.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.497-497
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• 2006

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.181-182
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• 2008

In this paper, an cost-effective system architecture is proposed to implement digital predistortion scheme for linearizing the PA amplifing TDD wideband signal. To make digital predistorted signal for compensating nonlinearity of PA, a dedicated ADC and a frequency-down converter are necessary. Proposed scheme is based on the TDD feature that the RF receiver frontend is idle state during the downlink signal processing time and utilize them to make the digital predistorted signal for PA.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.873-876
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• 1999

A variable gain amplifier(VGA) for wireless LAN is designed using active feedback. The amplifier is controlled by the gate voltage in the feedback path. This amplifier has more than 30㏈ gain variation and a improved linearity in the RF receiver block as input voltage increases. An active feedback topology is used by P-HEMT and is also analyzed for FET equivalent model.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.05a
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• pp.159-162
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• 1998

차세대 이동통신이 음성, 데이터, 동영상등 종합적인 멀티미디어 서비스를 목표로 하며, 세계 각국은 IMT-2000의 기술개발을 진행하고 있다 이런 서비스를 위해서는 광대역의 주파수를 필요로 하며, W-CDMA방식을 표준화하고 있다. 본 논문에서는 W-CDMA방식 단말기의 RF 수신부를 요구되는 규격에 따라 제작하고 그 성능을 테스트 하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.93-94
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• 2009

초음파를 이용한 거리 측정은 무선 센서네트워크에서 매우 중요하다. 본 논문에서는 Cricket 모트 두 개를 가지고 거리측정을 하여 정확도를 측정하였다. 거리 측정 방법은 RF 신호와, 초음파 신호의 시간 차를 이용한 TDOA 방식을 적용하였으며, 한 모트는 Sender, 다른 모트는 Receiver로 설정하여 직선거리에서 거리측정을 하였다.