• 한국광학회지
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• 제14권2호
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• pp.166-168
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• 2003

반도체 광증폭기의 이득포화원리를 이용한 전광 AND논리소자가 10 Gb/s에서 처음으로 구현되었다. 먼저 첫 번째 반도체 광증폭기에 B 신호를 입력시켜 반전된 신호인 Boolean (equation omitted)이 얻어졌다. 이와 같이 반전된 신호는 두 번째 반도체 광증폭기에 A신호와 함께 동시 입력되어 AND논리소자의 특성이 얻어졌다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.732-735
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• 1997

Variable Structure Controller(VSC) is usually known to have robustness to bounded exogenous disturbances. The robustness is attributed to the discontinuous term in the control input. However, this discontinuous term also causes an undesirable effect called chattering. To alleviate chattering, a hybrid controller consisting of VSC and Fuzzy Logic Controller(FLC) is proposed, which belongs to the category of Fuzzy Sliding Mode Controller(FSMC). The role of FLC in FSMC is to replace a fixed gain of a discontinuous term with a time-varying one based on a specified rule base. The characteristics of proposed controller are shown to be similar to those of VSC with a saturation function instead of sign function. The only remarkable difference is the nonlinearity whose form can be adjusted by free parameters, normalize gain, denormalize gain, and membership functions. Applied to AC servo motor, the proposed controller is compared with VSC in a regulation problem as well as a speed tracking problem. The simulation results show a substantial chatter reduction.

• 한국정보통신학회논문지
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• 제6권3호
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• pp.434-439
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• 2002

본 연구는 파장 분할 다중화(WDM：Wavelength Division Multiplexing) 방식 전송 시스템 (Transmission System)에 사용되는 어븀 첨가 광섬유 증폭기(EDFA : Erbium-Doped Fiber Amplifier)의 이득 제어(Gain Control) 방법에 관한 것으로 어븀 첨가 광섬유에서 상호 이득 포화(Cross Gain Saturation) 현상, 이득 비동질 (Gain In-homogeneity) 특성, 그리고 어븀 이온의 밀도 반전(Population Inversion)의 변화 에 의해 출력되는 다 파장 광 신호들의 광 세기가 각기 다르게 출력되는 현상을 고출력을 내도록 구성된 어븀 첨가 광섬유 증폭기와 고속 제어기를 구성하여 위 현상들을 억제하며 이득을 제어하기 위한 레이저 다이오드(Laser Diode : LD)의 제어전압 조사하고, 얻어진 결과들을 토대로 이득 제어에 적합한 방법을 제시하고 제어기를 설계한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.927-932
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• 2007

This paper proposes a robust back-stepping control with polynomial-type PD input for flexible joint robot manipulators to overcome parameter uncertainty. In the first step, a fictitious control is designed with polynomial-type PD input for the rigid link dynamic by the H-infinity control method. In second and third steps, the other fictitious control and real control are designed using saturation control and polynomial-type PD input based on the Lyapunov's second method. In each step, the designed robust inputs satisfy the L2-gain, which is equal to or less than gamma in the closed loop system. In contrast with the previous researches, the proposed method proves performance relations with PD gain from the robust gain. The performance robustness of the proposed control is verified through a 2-DOF robot manipulator with joint flexibility.

• 전자공학회논문지A
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• 제30A권5호
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• pp.45-51
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• 1993

An erbium doped fiber amplifier(EDFA) pumped by aingle 1.48$\mu$m LD was fabricated, and its gain and noise characteristics were measured. As a signal source, 1548 nm wavelength DFB LD was used. The small signal net gain of the EDFA module was 21.8 dB with maximum gain coefficient 0.7dB/mW for the erbium fiber length of 17.6 m, the pump power of 58 mW, and an input signal power of -25 dBm, respectively. The saturation power of the EDFA was 1 dBm for the input signal power of -5 dBm and the noise figure, measured by using an optical spectrum analyzer, was 5.8 dB for the input signal power of -40 dBm.

• 한국광학회지
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• 제8권3호
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• pp.236-240
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• 1997

광 귀환에 의해 이득이 고정된, 980 nm 펌프 EDFA의 귀환 파장에 따른 특성을 비교하였다. 귀환 파장으로 1532, 1543, 1565 nm의 세가지 파장을 선택하였으며, 각각의 경우에 대해 2.5 Gbps * 8채널, WDM시스템을 구성하여, 입력 신호광의 세기에 따른 이득의 변화, 상호 포화에 의한 신호광의 동 특성, relaxation oscillation에 의한 power penalty, 입력 신호광의 세기에 따른 잡음지수의 변화를 측정하여 비교하였다.

• 한국광학회지
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• 제11권3호
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• pp.187-192
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• 2000

반도체 레이저의 비션형 특성에 의하여 발생하는 매개증폭에 대하여, 반도체 레이저 다이오드의 비율방정식을 섭동 이론을 이용하여 해석하고 그 결과에 대하여 논의하였다. 매개증폭에 의하여 발생하는 이득은 펌프 변조전류가 증가하여 이득된 공진주파수에 가까워질수록 증가하였으며, 바이어스 전류와 반도체 레이저의 감쇄상수가 증가할수록 감소하였다. 또한 큰 매개이득을 얻기 위해서는 펌프 변조전류와 신호 변조전류 사이의 위상을 정합시켜야 하며, 큰 신호 변조전류에서는 증포된 광 출력의 포화로 인하여 매개이득이 감소하였다.

• Current Optics and Photonics
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• 제2권6호
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• pp.563-567
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• 2018

We propose and experimentally demonstrate a simple tunable photonic microwave band-pass filter with high resolution using a reflective semiconductor optical amplifier (RSOA) and an optical time-delay line. The RSOA is used as a gain medium for generating cross-gain modulation (XGM) effect as well as an optical source. The optical source provides narrow spectral width by self-injection locking the RSOA in conjunction with a partial reflection filter with specific center wavelength. Then, when the RSOA is operated in the saturation region and the modulated recursive signal is injected into the RSOA, the recursive signal is inversely copied to the injection locked optical source due to the XGM effect. Also, the tunability of the passband of the proposed microwave filter is shown by controlling an optical time-delay line in a recursive loop.

• Current Optics and Photonics
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• 제7권1호
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• pp.28-32
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• 2023

Frequency characteristics of gain-saturated erbium-doped fiber amplifier (EDFA) are experimentally evaluated to mitigate the optical signal fluctuation induced by atmospheric turbulence in terrestrial freespace optical communication systems. Here, an acousto-optic modulator (AOM) is used to emulate optical signal fluctuations induced by atmospheric turbulence. The waveform which is generated in proportion to the refractive-index structural parameters is used to drive the AOM at various periodic frequencies. Thus, the dependence of the signal fluctuation suppression on the frequency is evaluated. The experiment is conducted using a periodic frequency sweep of the AOM driving voltage waveform and signal input power variation of the amplifier. It is observed that a low periodic frequency and high input signal power effectively suppress the optical signal fluctuation. This study evaluates the experimental results from the high-pass filter and gain-saturation characteristics of the EDFA.

• 한국통신학회논문지
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• 제19권11호
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• pp.2228-2237
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• 1994

This paper describes the development of a Ku-band ($12.25GHz\sim12.75GHz$) SSPA intended as a replacement for TWTAs used in communication satelite transponder. The power stage of the amplifier consists of tow intrmally matched 8W FET divices combined using the branch-line coupler. To operate this stage, the drive stage has been designed with intermally matched 2W, 4W, 8W FET and two medium power FETs. The entire amplifier is made up by a aluminum chassis housing both the RF circuit and the bias circuitry. A regrlator/sequencing circuitry is used for FET biasing. The amplifier results implemented in this way show $41\pm0.3dB$ small-signal gain, 15W saturation power, a typical two tone $IM_3=-21.5dBc$ with single carrier backed off 5dB from saturation, $2^*/dBmax$ AM/PM conversion, and $3.47\pm0.25nsec$ group delay.