• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2000년도 종합학술발표회 논문집 Vol.10 No.1
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• pp.137-141
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• 2000

본 논문에서는 전력증폭기의 선형성을 광대역으로 개선하기 위하여 Delay 라인의 영향에 대하여 고려하려다. 사용된 전력 증폭기의 이득은 37dB이고, 3단의 l1W급으로 설계되었다. Error 증폭기는 4단으로 설계되었으며 이득은 55dB이다. 그리고 크기와 위상을조절하기 위한 장치로 Vector modulator를 사용하였으며, 또한 방향성 결합기 및 전력분배기를 설계하였다. 각 모듈을 통합하여 주파수 2.11GHz에서 2.2GHz까지 Delay 특성을 고려한 광대역 선형 전력 증폭기를 설계하였으며 대역폭이 30MHz에 걸쳐 IMD성분의 제거 특성이 25dB이상의 개선 효과를 얻었다.

• 전자공학회논문지A
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• 제32A권9호
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• pp.135-141
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• 1995

An optical digital parallel processor using Self-Pumped Phase Conjugate Mirror and liquid crystal spatial light modulator is presented and experimentally implemented. To use self-pumped PCM as memory, the mechanism for phase conjugation in two coupled interaction regions with the photorefractive crystal BaTiO$_{3}$ is investigated, especially the temporal behavior and effects of incident beam position. The optical design and implementation of matrix-vector multiplication using LCSLM and PCM memory is presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1084-1086
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• 2003

3-Phase BLDC Motor, which is generally used, has limited usage in high speed, due to pulsation torque occurring commutation and variable speed. To solve this problem, it is necessary to increase invariable, pole number, or the number of slots. Currently, due to rapid growth of semiconductor technology and trend toward smaller and cheaper production of switching device, multi-phase BLDC Motor for high speed, high output power is being actively pursued to produce. In this paper 7-Phase BLDC Motor drive system is designed and Vector modulator is studied.

• Journal of Microbiology and Biotechnology
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• 제14권2호
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• pp.356-365
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• 2004

In analyzing the region of the Amycolatopsis mediterranei S699 chromosome responsible for the biosynthesis of the ansamycin antibiotic rifamycin, we identified a gene, designated orj0, which is located immediately upstream of the rifamycin polyketide synthase (PKS). Orj0 encodes a protein, on the basis of sequence-comparative analysis, that is similar to several cytochrome P450 monooxygenases from different sources. The rifamycin producer, A. mediterranei, predominantly produces rifamycin B from its macrocyclic intermediate, proansamycin X, through dehydrogenation and hydroxylation steps. However, an A. mediterranei strain, deleted in orj0 by gene replacement, no longer produced rifamycin B. Furthermore, a versatile replicative vector in A. mediterranei was constructed and rifamycin B production was restored in a complementation experiment of orj0 using this novel vector. These consecutive results verified that the arf0 protein, which is a P450 hydroxylase, is required for the production of rifamycin B in A. mediterranei.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
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• pp.199-203
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• 2004

In this paper, we only describe the digital block of two-channel 18-bit analog-to-digital (A/D) converter employing sigma-delta method and xl28 decimation. The device contains two fourth comb filters with 1-bit input from sigma­delta modulator. each followed by a digital half band FIR(Finite Impulse Response) filters. The external analog sigma-delta modulators are sampled at 6.144MHz and the digital words are output at 48kHz. The fourth-order comb filter has designed 3 types of ways for optimal power consumption and signal-to-noise ratio. The following 3 digital filters are designed with 12tap, 22tap and 116tap to meet the specification. These filters eliminate images of the base band audio signal that exist at multiples of the input sample rate. We also designed these filters with 8bit and 16bit filter coefficient to analysis signal-to-noise ratio and hardware complexity. It also included digital output interface block for I2S serial data protocol, test circuit and internal input vector generator. It is fabricated with 0.35um HYNIX standard CMOS cell library with 3.3V supply voltage and the chip size is 2000um by 2000um. The function and the performance have been verified using Verilog XL logic simulator and Matlab tool.

• 한국통신학회논문지
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• 제41권11호
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• pp.1566-1573
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• 2016

본 논문은 무인기(UAV) 기반 공중 네트워크 시스템을 위한 polyphase In-phase/Quadrature-phase(I/Q) 네트워크 기반 빔-포밍 수신부를 제안한다. 제안하는 polyphase I/Q 네트워크는 낮은 Q-factor와 높은 임피던스를 갖기 때문에 작은 손실로 벡터 변조기를 구동할 수 있다. 벡터 변조기는 가변 이득 증폭기(VGA)로 구성되며, In-phase 및 Quadrature-phase 위상 신호의 진폭 제어 및 벡터 합을 통해 위상을 가변한다. 제안하는 빔-포밍 수신부는 TSMC $0.18{\mu}m$ CMOS 공정을 통해 구현하였다. 프로토타입은 5-6GHz 주파수 대역(-40dB 입력)에서 검증하였다. 6bit 벡터 변조기 제어를 통해 $5.6^{\circ}$ LSB (least significant bit)로 $360^{\circ}$ 위상 가변이 가능하다. 위상 오차는 평균 $1.6^{\circ}$이며, 진폭 오차는 평균 0.3dB이다.

• 한국산업융합학회 논문집
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• 제6권3호
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• pp.253-259
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• 2003

An experimental study was performed for turbulent flow behind a circular and a square cylinder by using 2-D PIV(Particle Image Velocimetry) technique in a cylindrical tube. The Reynolds number investigated were 10,000, 30,000 and 50,000. The measuring system consists of CCD camera. Ar-ion laser, image grabber and a host computer. The mean velocity vector, time mean axial velocity, turbulent intensity and Reynolds shear stress were measured along the test tube. The results are compared each other for the circular and the square cylinder.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1939_1941
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• 2009

The modulation quality of the RF transmitter in a wireless communication system usually affects system performance and it mostly depends on both a nonlinearity and a distortion, from the intermodulation products and the I/Q mismatch such as I/Q amplitude error and a local phase error, respectively. This paper focused on how much the error vector magnitude(EVM) which describes the modulation accuracy changes according to the variation of the I/Q mismatch components at I/Q modulator. For this work, the equation for the EVM including the I/Q mismatch components can be induced and calculated in accordance with the variation of the I/Q mismatch components. Consequently, the effect of I/Q mismatch components on the EVM, which is required in the transmitter specification of Personal Area Network, can be clearly analyzed.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.193-196
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• 2001

To reduce third-order intermodulation distortion(IMD3) generated in the down-conversion process of the mixer, predistortion technique was proposed and its performance was verified fDr Cellular band circuit. This method is based on the fact that down converted IMD3 of a down conversion mixer could be canceled by that of predistortor with a fine tuned vector modulator. Two tone test has been performed at 836 Mhz with 442 KHz separation. The results showed that IM3 level was improved about 16dB and PldB of the mixer was increased 3dB. from the above results, the suggested technique is useful to design the down converters for communication system .

• Current Optics and Photonics
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• 제1권2호
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• pp.85-89
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• 2017

It is shown that polarization singularities of a new type, namely U and P singularities, arise at the transverse cross section of a partially coherent beam, instead of the common singularities such as C points and L lines in a completely coherent vector field. A relationship between the two kind of singularities with respect to intensity is proposed. We also present a setup that can generate the new singularities, and any desired distribution of degree of polarization, using intensity control.