• Proceedings of the Korea Contents Association Conference
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• 2006.11a
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• pp.845-848
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• 2006

In this paper, a ETI management system for a variety of media services based on Terrestrial-Digital Multimedia Broadcasting(T-DMB) is introduced. This system consists of DMB I/O board and DMB multiplexer. The system transforms media data stream over IP(TCP/IP or UDP/IP) for these services to ETI frame(G.703) pushed to T-DMB transmitter.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.193-195
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• 2004

This paper presents a novel data transmit method using display units of mobile devices. Mobile devices such as personal-digital-assistants (PDAs) and cellular phones have a display unit. The typical display unit is a liquid-crystal-display (LCD) with an back-light. Since the proposed data transmit method uses the LCD or back-light as a data transmitter, it is a kind of sightable light communication. Tn order to transmit the data, the display unit drived by an application program on the platform of mobile devices. In this paper, detailed data transmit scheme, specific data protocol are presented and discussed. Finally, with the experimental results, usefulness of the proposed data transmit method is verified.

• Journal of Sensor Science and Technology
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• v.27 no.3
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• pp.143-149
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• 2018

In this paper, we introduce an edge-spike modulation method for visible light communication (VLC). This method is effective in preventing LED flicker and 120 Hz noise interference in base-band VLC. In the VLC transmitter, edge-spikes are generated by passing the digital data through a simple RC-high pass filter (HPF). The LED modulation of the edge-spikes does not change the average power of the LED light; thus it prevents LED flicker. In the VLC receiver, the 120 Hz noise from other lighting lamps is easily eliminated by RC-HPF, while the edge-spike signal is detected normally. In our experiment, the message of an air-quality sensor was successfully transmitted using edge-spike modulation. This structure is useful in constructing, e.g., wireless gas monitoring sensor systems to warn and prevent harmful gas leakage accidents in buildings using LED light.

• Broadcasting and Media Magazine
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• v.15 no.1
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• pp.78-89
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• 2010

국내의 지상파/위성 DMB는 개인 휴대용 수신기나 차량용 수신기를 통하여 언제 어디서나 다채널 멀티미디어 방송을 시청할 수 있는 이동형 방송서비스이다. 이러한 이동형 방송서비스에 스테레오스코픽 영상을 이용한 입체방송 서비스의 접목 시도가 활발히 진행 중이다. 스테레오스코픽 기술을 이용한 입체방송 서비스는 기존 2D영상 대비 실재감, 자연감, 선명성 등의 장점을 제공하며 3차원의 입체 형상을 구현할수있는신개념 서비스로서, 빠른 시장 정착과 대중화를 위해서는 플랫폼 구축과 관련 기기의 확산이 요구된다. 본 논문에서는 저사양/저대역의 이동방송 수신환경에서 스테레오스코픽 영상의 서비스를 위한 필요 요소기술을 도출하고 송수신 시스템을 제안한다.

• Journal of Power Electronics
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• v.14 no.6
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• pp.1139-1146
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• 2014

Digital signal processor (DSP) and field programmable gate array (FPGA) based concentrated control systems are designed for implementing CPS-SPWM strategies. The self-defined universal asynchronous receiver/transmitter (UART) protocol is used for communication between a master controller and an individual module controller via high speed links. Aimed at undesired pulse competition, this paper analyzes its generation mechanism and presents a new method for eliminating competition pulses with no time delay. Finally, the proposed concentrated controller is applied to a 10kV/10MVar distribution static synchronous compensator (DSTATCOM) industrial prototype. Experimental results show the accuracy and reliability of the concentrated controller, and verify the superiority of the proposed elimination method for competition pulses.

• Journal of Communications and Networks
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• v.1 no.2
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• pp.86-88
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• 1999

The Discrete Fourier Transform (DFT) and the Inverse Discrete Fourier Transform (IDFT) are commonly used in signal processing applications, in particular in digital communication sys-tems using the multi-carrier modulation principle. In such systems an IDFT is computed at the transmitter end, and a DFT at the re-ceiver end. This paper examines a technique of computations, for which only negligible differences appear between the DFT and the IDFT calculations while the number of arithmetic operations re-quired is substantially reduced. This offers significant advantages for the design of an IDFT/DFT processor for Discrete Multitone(DMT) systems.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.445-449
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• 1988

Digital processing of measured data offers a powerful means to improve the resolution and quality of ultrasonic imaging. The present research demonstrates that filtering typical B-scan images using Wiener filter enhances lateral resolutions by more than 50 percent. The filter is operated using the measured signal amplitude across the transmitter beam and the beam with. It is optimized for low noise and high resolution By an empirical approach. This bethod for lateral filtering produces a very useful result for the line images with high interference by neighboring lines.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.11
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• pp.2942-2953
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• 1996

This paper studies the effect of intersymbol interference due to sampling-time jitter on the worst-case bit error probability in a digital modultation over an additive white Gaussian noise channel, with the squared-root raised-cosine filters in the transmitter and the receiver. It derives approximation formulas using the Taylor series approximations. the principal results of this paper is the relationship between the worst-casse bit error probability, the degree of jitter, the roll factor of the raised cosine filter, and other quantities. Numerical results show, as expected, that the intersymbol interference decreases as the roll-off factor increases and the jitter decreases. They also show that the approximation formulas are accurate for smally intersymbol interference, i.e., for large roll-noise ratio $E_{b/}$ $N_{0}$.leq.7 dB and begin to lose accuracy for larger signal-to-noise ratio.o.o.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.5
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• pp.68-75
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• 1994

A new Predistortor that is designed using Feedforward type is proposed to overcome the nonlinearity of HPA (High Power Amplifier). HPA has the nonlinearity of the gain compression and phase distorton, so digital communication system of multi-carrier TDMA needs the linear RF transmitter. Using IMD (Intermodulation Distortion) of drive amplifier, as Feedforward type, the inverse IMD is coupled to the main loop with variable attenuators, phase shifters, and sub-amplifiers well designed. At the input of main amplifier, the over-coupled IMD surpresses the main amplifier 's IMD. Adjusting the level and phase of IMD at the sub loop, C/I of HPA is better than before correction.

• Electronics and Telecommunications Trends
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• v.9 no.4
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• pp.131-138
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• 1994

최근 무선통신의 활성화에 따라, V/UHF(very/ultra high Frequency) 대역에서 한정된 주파수를 효율적으로 이용하기 위한 방법의 하나로서, 점차 점유 주파수 대역의 폭을 축소하여 보다 많은 이용자를 수용하도록 무선 채널의 협대역화가 추진되고 있다. 본 고에서는 먼저 V/UHF 대역 무선 통신에서 채널의 협대역화에 관련된 기술 중에서 현재까지 사용되고 있는 FM(frequency modulation), AM(amplitude modulation) 변조 방식의 장,단점을 살펴본후, 새로운 LM(linear modulation) 변조 방식에 대한 기술적 배경 및 특성을 알아보았다. LM은 SSR(single side band)-AM이 발전한 것으로서, TTIB(transparent tone-in-band), CLT(Cartesian loop transmitter), FFSR(feed-forward signal regeneration), DSP(digital signal processing)등 4가지의 기술이 결합하여 만들어진 것이다. LM 방식에 사용된 4가지 기술을 소개하고, 기존의 변조 방식에 비해 개선된 사항에 대해 서술한다.