• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.9
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• pp.7-13
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• 2009

This paper presents a multi-channel transceiver that achieves a data rate of 3.125Gb/s/ch. The LVDS is used because of its noise immunity and low power consumption. And a pre-emphasis circuit is also proposed to increase the transmitter speed. On the receiver side, a low-power CDR(clock and data recovery) using 1/4-rate clock based on dual-interpolator is proposed. The CDR generates needed additional clocks in each recovery part internally using only inverters. Therefore each part can be supplied with the same number of 1/4-rate clocks from a clock generator as in 1/2-rate clock method. Thus, the reduction of a clock frequency relaxes the speed limitation and lowers power dissipation. The prototype chip is comprised of two channels and was fabricated in a $0.18{\mu}m$ standard CMOS process. The output jitter of transmitter is loops, peak-to-peak(0.31UI) and the measured recovered clock jitter is 47.33ps, peak-to-peak which is equivalent to 3.7% of a clock period. The area of the chip is $3.5mm^2$ and the power consumption is about 119mW/ch.

• Journal of IKEEE
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• v.16 no.1
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• pp.62-68
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• 2012

The planar microstrip antenna for the safety communication of life at sea is designed and manufactured to effectively receive the emergency wireless signal from the transmitter on the life vest. The proposed microstrip antenna in this paper is easy to make, light weight and cheap compared to other antennas because of printed antenna fabrication. To overcome the narrow bandwidth, large size and low gain characteristics of microstrip antenna, we use the IDMA(Identical Dual Patch Microstrip Antenna with Air-Gap) structure. The proposed antenna was fabricated with the use of 1.6mm FR4 and measured with the 28.7MHz(6.6%) of bandwidth and 3.04dBi of gain at the frequency of 426MHz. To validate the proposed antenna, we experimented the possible distance range at sea using the commercial UHF transceiver module and obtained over 5km distance for stable communication. This antenna can be widely applied to application of the UHF wireless mobile communication.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.6
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• pp.86-93
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• 2009

We investigate lattice-reduction-aided precoding techniques for multi-user multiple-input multiple-output (MIMO) channels. When assuming full knowledge of the channel state information only at the transmitter, a vector perturbation (VP) is a promising precoding scheme that approaches sum capacity and has simple receiver. However, its encoding is nondeterministic polynomial time (NP)-hard problem. Vector perturbation using lattice reduction algorithms can remarkably reduce its encoding complexity. In this paper, we propose a vector perturbation scheme using Seysen's lattice reduction (VP-SLR) with simultaneously reducing primal basis and dual one. Simulation results show that the proposed VP-SLR has better bit error rate (BER) and larger capacity than vector perturbation with Lenstra-Lenstra-Lovasz lattice reduction (VP-LLL) in addition to less encoding complexity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.12
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• pp.1102-1109
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• 2013

Blind interference alignment (BIA) scheme has demonstrated a way of interference alignment (IA) without channel state information at transmitter (CSIT). While it shows superior performance in high signal-to-noise ratio (SNR) regime stemming from the maximal degrees of freedom (DoF) gain, BIA scheme achieves inferior sum-rate performance in low SNR regime. This paper proposes a dual-mode transmission strategy which switches between single user (SU) SISO with receive mode selection and the BIA scheme depending upon the range of SNR. First, we derive a closed-form achievable rate for each transmission-mode. Secondly, we propose a low-complex transmission-mode selection algorithm.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.8 s.338
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• pp.1-6
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• 2005

A dual-level low voltage differential signalling (DLVDS) circuit is proposed aiming at reducing transmission lines for LCD driver IC. In the proposed circuit, we apply a couple of primitive data to DLVDS circuit as inputs. The transmitter converts two inputs to two kinds of fully differential level signals. In this circuit, two transmission lines are sufficient to transfer two primitive inputs while keeping the LVDS feature. The receiver recovers The original input data through a level decoding circuit. We fabricated the proposed circuit using $0.25\mu m$ CMOS technology. The resultant circuit shows 1-Gbps/2-line data rate and 35-mW power consumption at 2.5V supply voltage, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.12 s.115
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• pp.1224-1230
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• 2006

In this paper, for spatial multiplexing with limited feedback, a precoding scheme is proposed based on the joint use of minimal instantaneous feedback and long-term feedback of a small number of bits, wherein the long-term feedback is used to convey a selected preceding matrix within a precodercodebook consisting of a number of unitary matrices, and the active column vectors of the selected unitary matrix are conveyed to the transmitter using instantaneous feedback. Focusing on the case of dual multi-input multi-output(MIMO) systems, precoder codebook design for maximizing the average throughput of a spatial multiplexing system with a zero-forcing(ZF) receiver is proposed. It is shown that the proposed scheme provides a considerable throughput enhancement over multi-mode antenna selection and multi-mode basis selection only with the additional long-yterm feedback of a small number of bits. For example, the throughput increases by 11.5 % than antenna selection and 5.1% than basis selection, respectively, when SNR=20 dB.

• The Journal of the Korea Contents Association
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• v.6 no.3
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• pp.38-45
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• 2006

A dual-level low voltage differential signalling (DLVDS) circuit is proposed aiming at reducing transmission lines for a LCD driver IC. We apply two data to the proposed DLVDS circuit as inputs. Then, the transmitter converts two inputs to two kinds of fully differential signals. In this circuit, two transmission lines are sufficient to transfer two inputs while keeping the LVDS feature. However, the circuit has a common mode bias fluctuation due to difference of the input bias and the reference bias. We compensate the common mode bias fluctuation using a feedback circuit of the current source bias. The receiver recovers the original input data through a level decoding circuit. We fabricated the proposed circuit using $0.25{\mu}m$ CMOS technology. The simulation results of proposed circuit shows 1-Gbps/2-line data rate and 35mW power consumption at 2.5V supply voltage, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.1027-1031
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• 2006

Recently, mobile-type analysis system when emergency patient can check his blood condition in the transportation or vessel has being required. Under the present system, it takes lots off-time to know the blood analysis result of patient, so, it may lead to a dangerous situation. But, in this study, analysis time makes to fall down to $1{\sim}min$. to emergency treatment patient more quickly, and you can check the information by wireless PC through Bluetooth base. It is able to measure in about 7minutes from 25minutes of warming-up time in existing facilities by testing temperature peculiarity curve, to operate system without error even minute temperature change by adoption DUAL heating. And Bluetooth base was adopted to reduce power consumption and be able to hospital networking by keeping and sending analyzed data when it needs.

• Journal of the Korean Institute of Telematics and Electronics
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• v.9 no.5
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• pp.19-26
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• 1972

A newly developed quartz frequency modulator utili3ing a V. V. C. diode is briefly described. Its electrical characteristics-including modulation linearity, modulation distortion, and carrier frequency stability depending upon the variation of the environmental temperature and the applied power voltage, etc.-are suitable for the modulator of a mobile or a portable F.M. transmitter according to the experimental results. The excellent over-all electrical characteristics were proved from the experimental development of the two kinds of transceivers. One is the single channal transceiver which contains a direct frequency modulator at the carrier frequency of 52.750 MHg. The other is the dual channel transceiver (the frequencies are selected from about 40 channels without tuning adjustment) whose operational frequency is composed of a modulated frequency of 10.7 MHz and the frequency generated at a channel control oscillator, As mentioned above, it is realized that the electrical characteristics of this modulation method are suitable for portable F. M. transceivers.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.109-114
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• 2003

Wireless communication systems are inevitable for efficient underwater activities. Because of the poor propagation characteristics of light and electromagnetic waves, acoustic waves are generally used for the underwater wireless communication. Although there are many kinds of information type, visual images take an essential role especially for search and identification activities. For this reason, we developed an acoustic-based underwater image transmission system under a dual use technology project supported by MOCIE (Ministry of Commerce, Industry and Energy). For the application to complicated and time-varying underwater environments all-digital transmitter and receiver systems are investigated. Array acoustic transducers are used at the receiver, which have the center frequency of 32kHz and the bandwidth of 4kHz. To improve transmission speed and quality, various algorithms and systems are used. The system design techniques will be discussed in detail including image compression/ decompression system, adaptive beam- forming, fast RLS adaptive equalizer, ${\partial}/4$ QPSK (Quadrilateral Phase Shift Keying) modulator/demodulator, and convolution coding/ Viterbi. Decoding.