• Journal of electromagnetic engineering and science
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• 제17권2호
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• pp.105-107
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• 2017

The self-biasing circuit through a feedback resistor is applied to a gallium nitride (GaN) distributed power amplifier (PA) monolithic microwave circuit (MMIC). The self-biasing circuit is a useful scheme for biasing depletion-mode compound semiconductor devices with a negative gate bias voltage, and is widely used for common source amplifiers. However, the self-biasing circuit is rarely used for PAs, because the large DC power dissipation of the feedback resistor results in the degradation of output power and power efficiency. In this study, the feasibility of applying a self-biasing circuit through a feedback resistor to a GaN PA MMIC is examined by using the high operation voltage of GaN high-electron mobility transistors. The measured results of the proposed GaN PA are the average output power of 41.1 dBm and the average power added efficiency of 12.2% over the 6-16 GHz band.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.390.1-390.1
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• 2016

The present work explains the interfacial energetics of all oxide transparent photodiodes. The optical, structural and morphological of copper oxides were systematically analyse by UV-Visible spectrometer, X-Ray diffraction, Raman spectroscopy, Scanning electron microscopy (SEM) and Atomic force microscopy measurements (AFM). The UV-Visible result exhibits optical bandgap of Cu2O and CuO as 2.2 and 2.05 eV respectively. SEM and AFM result shows a uniform grain size distribution in Cu2O and CuO thin films with the average grain size of 45 and 40 nm respectively. The results of Current-Voltage and Kelvin probe force microscope characteristics describe the electrical responses of the Cu2O/ZnO and CuO/ZnO heterojunctions photodiodes. The obtained electrical response depicts the approximately same knee voltages with a measurable difference in the absolute value of net terminal current. More over the present study realizes the all oxide transparent photodiode with zero bias photocurrent. The presented results lay the template for fabricating and analysing the self-bias all oxide transparent photodetector.

• 전자공학회논문지D
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• 제35D권5호
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• pp.1-10
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• 1998

A GaAs MMIC composed of VCO (voltage controlled oscillator) and mixer for PCS receiver has been developed using 1.mu.m ion implanted GaAs MESFET process. The VCO consists of a colpitts-type oscillator with a dielectric resonator and the circuit configuration of the mixer is a dual-gate type with an asymmetric combination of LO and RF FETs for the improvement of intermodulation characteristics. The common-source self-biasing is used in all circuits including a buffer amplifier and mixer, achieving a single power supply (3V) operation. The total power dissipation is 78mW. The VCO chip shows a phase noise of-99 dBc/Hz at 100KHz offset. The combined VCO/mixer chip shows a flat conversion gain of 2dB, the frequency-tuning factor of 80MHz/volts in the varacter bias ranging from 0.5V to 0.5V , and output IP3 of dBm at varactor bias of 0V. The fabricated chip size is 2.5mm X 1.4mm.

• 전자공학회논문지D
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• 제34D권10호
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• pp.14-23
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• 1997

An MMIC downconverting mixer for cellular phone application has been successfully developed using an MMIC process including $1 \mu\textrm{m}$ ion implanted gaAs MESFET and passive lumped elements consisting of spiral inductor, $Si_3N_4$ MIM capacitor and NiCr resistor. The configuration of the mixer presented in this paper is single-ended dual-gate FET mixer with common-source self-bias circuits for single power supply operation. The dimension of the fabricated circuit is $1.4 mm \times 1.03 mm $ including all input matching circuits and a mixing circuit. The conversion gian and noise figure of the mixer at LO powr of 0 dBm are 5.5dB and 19dB, respectively. The two-tone IM3 characteristics are also measured, showing -60dBc at RF power of -30dBm. Allisolations between each port show better than 20dB.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1877-1880
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• 2005

This paper proposed the new current feed-back amplifier for low supply voltage application. The input stage was designed to be a class-AB circuit and achieve the low supply-voltage operation down to $2V_{TH}+2V_{DS(SAT)}$. With the self-adjust bias current, the high performance can be adopted with high stability. The circuit was successfully proven by the simulation with MOSIS 0.5 ${\mu}$m MOS technology.

• 전자공학회논문지D
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• 제35D권4호
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• pp.1-8
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• 1998

An MMIC single-balanced upconverting mixer for PCS application has been successfully developed using an MMIC process employed by 1 .mu. ion implanted GaAs MESFET and passive lumped elements consisting of spiral inductor, Si3N4 MIM capacitors and NiCr resistors. The configuration of the mixer presented in this paper is two balanced cascode FET mixers with common-source self-bias circuits for single power supply operation. The dimension of the fabricated circuit including two active baluns intermodulation characteristic with two-tone excitation are also measured, showing -28.17 dBc at IF power of -30 dBm.

• Advances in Computational Design
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• 제1권3호
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• pp.275-296
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• 2016

This article presents an adaptive directional differential evolution (ADDE) algorithm and its application in solving discrete sizing truss optimization problems. The algorithm is featured by a new self-adaptation approach and a simple directional strategy. In the adaptation approach, the mutation operator is adjusted in accordance with the change of population diversity, which can well balance between global exploration and local exploitation as well as locate the promising solutions. The directional strategy is based on the order relation between two difference solutions chosen for mutation and can bias the search direction for increasing the possibility of finding improved solutions. In addition, a new scaling factor is introduced as a vector of uniform random variables to maintain the diversity without crossover operation. Numerical results show that the optimal solutions of ADDE are as good as or better than those from some modern metaheuristics in the literature, while ADDE often uses fewer structural analyses.

• 전자공학회논문지SC
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• 제37권2호
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• pp.60-68
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• 2000

본 논문에서는 표준 메모리 공정에 구현이 가능한 CMOS 전류원의 설계 기법에 대해 논한다. 제안하는 설계기법은 자기바이어스 기법을 활용하여 공급전압의 변화에 대해 매우 좋은 특성을 갖고, 새로운 온도보상 기법을 통해 온도변화에 대한 출력전류 변이의 일차성분을 제거할 수 있으며, 칩 내의 전압잡음에 강한 새로운 전류감지 스타트업 회로를 포함한다. 이러한 CMOS 전류원의 회로설계 기법과 함께 제안된 CMOS 전류원을 초고속 DRAM의 클록 발생회로에 적용할 수 있는 방법에 대해서도 논의한다. 본 논문에서 제안된 CMOS 전류원의 설계기법은 해석적인 방법과 함께 회로 시뮬레이션을 통해 그 유용성을 입증한다.

• 한국ITS학회 논문지
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• 제10권1호
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• pp.42-48
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• 2011

본 논문에서는 GaN HEMT (Gallium Nitride High Electron Mobility Transistor) bare-chip을 이용하여 X-대역에서 수동로드 풀(Passive load-pull)을 수행하였다. 열로 인한 특성 변화가 최소화 된 동작 조건을 얻기 위해 드레인 바이어스 전압과 입력 RF 신호를 펄스로 인가하였다. 전자기장 시뮬레이션과 회로 시뮬레이션을 병행하여, 와이어 본딩 효과를 고려하여 드레인 경계면에서의 정확한 임피던스 정합 회로를 구현하였다. 임피던스를 변화시키기 위해 마이크로스트립 라인 스터브의 길이가 조절 가능한 회로를 설계하였다. 펄스 로드 풀 실험 결과 8.5 GHz에서 9.2 GHz 대역에서 최대 42.46 dBm의 출력 전력을 얻었으며, 58.7%의 드레인 효율 특성을 얻었다.

• 대한간호학회지
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• 제30권3호
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• pp.709-719
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• 2000

The purposes of the study was to identify the depression of women after a hysterectomy and to clarify the factors related to depression. This was a cross-sectional descriptive study. The data was collected by a mailed questionnaire that was composed of the Zung Self-Rating Depression Scale(SDS), support scale of husband and socio-demographic variables from 255 women undergoing hysterectomies for any nonmalignant condition in S. University Hospital. They also must have lived with their spouses from 3 months to 2 years after the operation. The results were as follows: 1. The SDS mean was 42.25 and range was 21 to 67. The incidence of clinical depression (over SDS 50) was 20.8% from 3 months to 2 years after a hysterectomy. 2. The depression of women in 18-24 months after surgery (39.80) was lower than that of any other periods such as 3-5 months, 6-12 months, and 13-17 months (p<0.01). 3. The support form husband was negatively correlated with the depression of women after a hysterectomy. 4. Depression among women tho had hysterectomies were associated with lower income, less sexual satisfaction, the feeling of being asexual, and the bias of concept the uterus controlling general health.