• 전자공학회논문지B
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• 제30B권11호
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• pp.27-36
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• 1993

It is well know that the tuning method of Yuwana-Seborg (1982) can not be even applied to the relatively small delay system due to the phase errors from the Pad approximation suh (1984, 85, 86). Jutan and Rodriguez(1984), lee(1989), Chen(1989), Lee and Edgar(1990), etc have been tried to improve it. In this stydy, such recent results and their problems are investigated. A new tuning method by "a frequency scale transformation". which is based on a previous result of Suh(1984). is proposed. It can reduce the magnitude of the phase error significantly.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.47.6-47
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• 2001

In this paper a new indirect robust self-tuning regulator is proposed including an inverse system of a plant and a robust compensator such that it achieves the desired frequency shape specified by solving the mixed H$\infty$ sensitivity problem within a prescribed tolerance in the H$\infty$ norm. Consequently, in the proposed self-tuning regulator, robust stability is guaranteed in spite of the identification error.

• Current Optics and Photonics
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• 제2권1호
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• pp.53-58
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• 2018

A novel X-band high speed frequency sweep signal generator based on a tunable optoelectronic oscillator (OEO) incorporating a frequency-swept laser is presented and the theoretical fundamentals of the design are explained. A prototype of the generator with tuning range from 8.8552 GHz to 10.3992 GHz and a fine step about 8 MHz is achieved. The generated radiofrequency signal with a single sideband (SSB) phase noise lower than -100 dBc/Hz@10KHz is experimentally demonstrated within the whole tunable range, without any narrow RF band-pass filters in the loop. And the tuning speed of the frequency sweep signal generator can reach to over 1 GHz/s benefiting from applying a novel dispersion compensation modular instead of several tens of kilometers of optical fiber delay line in the system.

• 한국정밀공학회지
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• 제18권11호
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• pp.58-66
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• 2001

GPC has been reported as a useful self-tuning control algorithm for systems with unknown time-delay and parameters. GPC is easy to understand and implement, and thus has won popularity among many practicing engineers. Despite its success, GPC does not guarantee is nominal stability. So, in this paper, GPC is rederived in frequency domain instead of in the time domain to guarantee its nominal stability. Derivation of GPC in frequency domain involves spectral factorization and Diophantine equation. Frequency domain GPC control law is stable because the zeros of characteristic polynomial are strictly Schur. Recursive least square algorithm is used to identify unknown parameters. To see the effectiveness of the proposed controller, the controller is simulated for a numerical problem that changes in dead-time, in order and in parameters.

• 한국군사과학기술학회지
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• 제8권3호
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• pp.64-72
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• 2005

In this paper, we propose a design method of the millimeter-wave(W-Band) waveguide cavity harmonic voltage controlled oscillator(VCO) using a Gunn diode for the armor sensor. Using the 3-dimensional simulation tool(Ansoft $HFSS^{TM}$), we were able to find the impedance matching point between waveguide and Gunn diode and estimate the oscillation frequency. A varactor diode is used for the frequency tuning, and we find out the equation for the calculation of the tunable frequency range. The designed VCO shows good performances; 17dBm output power at 94GHz center frequency, 520MHz frequency tuning range similar to the estimated value(480MHz).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
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• pp.321-322
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• 2008

주파수는 발전기 조속기와 전적거래소 EMS AGC의 협조제어 체계가 적절하여야 안정적인 운영이 가능하며, 과다한 주파수 조정은 경제급전을 저해함은 물론 발전기의 수명단축을 초래하기 때문에 AGC 최적튜닝은 필수적이다. 본 논문에서는 '07년도에 거래소 계통운영처에서 수행한 AGC 제어파라미터 튜닝기법 및 효과에 대해 논하고 있으며, 학계는 물론 동종업계에 AGC 관련 기술개발시 업무추진에 도움이 되었으면 한다.

• 전기학회논문지
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• 제63권7호
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• pp.883-888
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• 2014

The paper describes the parameter tuning of power system stabilizer (PSS) for a power plant based on hybrid system modeling. The existing tuning method based on bode plot and root locus is well applied to keep power system stable. However, due to linearization of power system and an assumption that the parameter ratio of the lead-lag compensator in PSS is fixed, the results cannot guarantee the optimal performances to damp out low-frequency oscillation. Therefore, in this paper, hybrid system modeling, which has a DAIS (differential-algebraic-impusive-switched) structure, is applied to conduct nonlinear modeling for power system and find optimal parameter set of the PSS. The performances of the proposed method are carried out by time domain simulation with a single machine connected to infinite bus (SMIB) system.

• 전기학회논문지
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• 제58권12호
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• pp.2416-2419
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• 2009

We performed frequency response measurements of four tuning fork crystal oscillators with different sizes and analyzed their measured electrical equivalent circuit parameters of R, L, $C_S$, and $C_P$ as functions of the linear dimensions, length, width, and thickness. We observed that R and L showed an decreasing behavior with increasing length while $C_S$, and $C_P$ showed an increasing behavior. Similar dependences of the electrical parameters on thickness were also observed. On the contrary, any noticeable dependence of these parameters on width has not been found.

• Journal of electromagnetic engineering and science
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• 제11권4호
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• pp.235-238
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• 2011

In this paper, a novel low phase noise voltage-controlled oscillator (VCO) using metamaterial structure and rat race coupler is presented for reducing the phase noise without the reduction of the frequency tuning range. The metamaterial structure has been realized by microstrip square open loop double split ring resonator (SRR). The rat race coupler shows slightly higher transmission compared to a Wilkinson combiner and is, therefore, used instead to improve the performances of VCO. By providing these unique modifications, the proposed push-push VCO has a phase noise of -126.30~-124.83 dBc/Hz at 100 kHz in the tuning range of 5.672~5.800 GHz.

• 대한전자공학회논문지
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• 제26권12호
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• pp.2016-2024
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• 1989

A versatile incoherent optical processing system is developed and analyzed in detail, in which an acousto-optic modulator is used to generate the temporal offset frequency for heterodyning and an optical scanner to process the input object in scanning mode. The operational characteristics of the systems are studied with respect to spatial filtering in terms of the spectral width change of the light source, the temporal offset frequency, and a scanning rate. To enhance the system's capability, two schemes for tuning the system's OTF, structural tuning and defocused object tuning, are also developed and verified with the MTF measurements and computer calculations.