• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11A
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• pp.1063-1071
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• 2008

This paper proposes a prior maximum likelihood (ML) detection verifier which has an ability to verify if the zero forcing (ZF) detection results are identical to the ML detection results. Since more than 90% of ZF detection results are identical to ML detection results, the proposed verifier makes it possible to omit the computationally complex ML detection in 90% cases of MIMO signal detections. The proposed verifier is designed by using the diversity gain obtained from converting MIMO signal into single input multiple output (SIMO) signals. In the proposed method, single input multiple output (SIMO) signals for each transmit antenna are separated from MIMO signals after the MIMO signals are detected by ZF method. Computer simulations show that the true alarm probability of the proposed verifier is more than 80% and the false alarm probability is less than $10^{-4}$.

• Journal of IKEEE
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• v.11 no.1 s.20
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• pp.24-29
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• 2007

In this paper, we developed a Mac-Yule measurement system which consider psychological stable state of patience. The developed system consist with a hardware device that can derive a EEG, respiration and pulse wave, and a software which acquire a biological signal and signal processing The EEGs are derived with bipolar method from frontal head. The respiration signals obtain from nasal front with a transducer which consist with thermistor bridge. The pulse waves are detected from earlobe with photoplethysmograph method. A power spectrum of EEG are used as the decision parameters of psychological stable state of patience. The decision of Mac-Yule are defined as origin text method that of numbers of pulse to 1 respiration period. As the results of experiment with developed system, we could have a spectrum band discretion of EEG signal, stable respiration signal detection and automatic gain controlled pulse signal with realtime. And then, we could detect Mac-Yules from processed signals.

• Journal of IKEEE
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• v.18 no.1
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• pp.172-178
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• 2014

This paper describes the design technique and the method of analog front-end to measure the saturation of hemoglobin with oxygen sensor. To process the $SpO_2$ value from the sensor, the current data from the sensor should be converted into voltage domain. Designed analog front-end usually converts the current data from the sensor into voltage domain data to pass it on analog-to-digital converter called ADC with a different level of gain characteristics. This circuit was fabricated in a $0.11{\mu}m$ CMOS technology and has 4 level of gain properties. The occupied area is $0.174mm^2$.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.3
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• pp.95-100
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• 2007

In this paper, a twice folded TEM horn antenna for 70 kV impulse high power system is proposed. The length reduction of 50 % is achieved by folding a conventional TEM horn antenna twice. The array elements are fed by the stripline power divider using the Chebyshev transformer. The power divider feeds four TEM horn antenna elements with an in-phased uniform power, and it covers a wide bandwidth ($150\;MHz\;{\sim}\;768\;MHz$, VSWR<2.0). Considering the air breakdown at peak 70 kV impulse, the proposed antenna maintains the 25 mm gaps between conducting plates. The dimension of the twice folded horn antenna is $1730\;{\times}\;1600\;{\times}\;300$ (mm3), and the operating frequency is from 152 MHz to 750 MHz under 10 dB return loss. The peak gains are measured from 6.77 dBi to 10.70 dBi at $400\;MHz\;{\sim}\;750\;MHz$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.862-867
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• 2009

This paper presents a study on a rectenna for rectification of incident low power microwave signals with power densities less than 2 mW/$cm^2$ at 2.45 GHz. The proposed rectenna is designed and implemented by a rectifier with voltage doubler structure and a printed Yagi antenna which suppress re-radiation of the second order harmonic of fundamental frequency. The printed Yagi antenna has a gain of about 5 dB, and the measured conversion efficiencies of the rectenna are from 32 % to 42 % when its incident power levels are from 0 dBm to 14 dBm. The developed rectenna is expected to be useful in the power transmission system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.1
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• pp.197-204
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• 2010

This paper proposes a new body-effect compensated switch configuration for low voltage and low distortion switched-capacitor (SC) applications. The proposed circuit allows rail-to-rail switching operation for low voltage SC circuits and has better total harmonic distortion than the conventional bootstrapped circuit by 19 dB. A 2-1 cascaded sigma-delta modulator is provided for performing the high-resolution analog-to-digital conversion on audio codec in a communication transceiver. An experimental prototype for a single-stage folded-cascode operational amplifier (opamp) and a 2-1 cascaded sigma-delta modulator has been implemented m a 0.25 micron double-poly, triple-metal standard CMOS process with 2.7 V of supply voltage. The 1% settling time of the opamp is measured to be 560 ns with load capacitance of 16 pF. The experimental testing of the sigma-delta modulator with bit-stream inspection and analog spectrum analyzing plot is performed. The die size is $1.9{\times}1.5\;mm$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11A
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• pp.1146-1153
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• 2007

In this paper, we analyze the I/Q imbalances effects at the WiBro uplimk when using direct-conversion RF transceiver. If I/Q imbalance exists, the transmit signal is spread over two sbcarriers. As a result, phenomenon of performance reducing is produced. Contrary to OFDM system in which one user uses all subcarrier, symmetrical two subcarriers are assigned other users in OFDMA system. I/Q imbalances elements can't be estimated such a conventional allocation method of tiles in subchannel and compensated. In order to solve the problem, We propose a new method in order that symmetrical two subcarriers are assigned one user. If novel method is applied, we can estimate I/Q imbalances and compensate distortion received signal. As a result, we can obtain a performance similar performance when I/Q imbalances is not existed. Also, if proper detection methods are used, we get the effect of performance improvement, because of diversity gain what is happened due to combining I/Q imbalances with multi path fading channel.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.242-246
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• 2012

This paper presents an integrated low noise and highly linear wideband RF front-end for a digital terrestrial and cable TV tuner, which are used as a part of double-conversion TV tuner. The low noise amplifier (LNA) has a low noise figure and high linearity by adopting a noise canceling technique based on current amplification. The up-conversion mixer and SAW buffer have high linearity by employing a third order intermodulation cancellation technique. The proposed RF front-end is designed in a $0.18{\mu}m$ CMOS and draws 60 mA from a 1.8 V supply voltage. The RF front-end shows a voltage gain of 30 dB, an average single side-band noise figure of 4.2 dB, an IIP2 of 40 dBm, and an IIP3 of -4.5 dBm for the entire band from 48 MHz to 862Hz.

• 전자공학회논문지 IE
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• v.47 no.4
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• pp.53-58
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• 2010

In this paper we propose symbol decision method reflecting the color non-uniformity in 3-dimensional color space. By comparing with 2-dimensional color space decision method, we show the superiority of BER performance of the proposed method. Proposed method may reflect the non-uniformity since the symbol decision boundary in color space is transformed from 3D RGB space, and one dimension corresponding to Y value is added. Therefore, we can obtain the better BER performance by using the symbol decision method in 3D color space. In this paper, through numerical simulation, show the superior BER performance of 3D color space symbol decision method compared with 2D color space symbol decision method under AWGN and common mode noise channel.

• 전자공학회논문지 IE
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• v.47 no.4
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• pp.1-9
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• 2010

This paper describes a ultrasonic signal processing front-end IC for distance range meter and body detector. The burst shaped ultrasonic signal is generated by a self oscillator and its frequency range is about 40[kHz]-300[kHz]. The generated ultrasonic signal transmit through piezo resonator. The another piezo device transduce from received ultrasonic signal to electrical signals. This front-end IC contained low noise amplifier, band pass filter, busrt detector and time pulse generator and so on. This IC has two type of new idea for improve function and performance, which are self frequency control (SFC) and Variable Gain Control amplifier (VGC) scheme. The dimensions and number of external parts are minimized in order to get a smaller hardware size. This device has been fabricated in a O.6[um] double poly, double metal 40[V] High Voltage CMOS process.