• Current Optics and Photonics
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• 제2권6호
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• pp.525-531
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• 2018

The effect of eccentricity on dispersion and nonlinear properties of a photonic crystal fiber having elliptical air holes is investigated using a fully vectorial effective index method. It is found that the effective refractive index increases with increase of eccentricity. The dependence of dispersion and nonlinear properties of the PCF on the eccentricity of the air hole is investigated. It is revealed that eccentricity of the air hole affects the zero dispersion wavelength. Further, the nonlinear properties such as mode field area, nonlinear coefficient and self phase modulation of the Photonic crystal fibers are analyzed. The mode field area increases and the nonlinear coefficient decreases with increase in eccentricity. The variation of the self phase modulation with elliptical air hole is also discussed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.60.1-60
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• 2002

. an output feedback stabilizing controller for non-minimum phase nonlinear systems . Assumption 1 : the Jacobi linearization of the given nonlinear linear system is controllable . Assumption 2: an appropriate transformation which transforms the zero dynamics into a special form . Assumption 3: the system satisfies the observability rank condition . Augmentation of systems by augmented by a chain of integrators

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 추계학술대회 논문집
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• pp.52-53
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• 2012

This paper presents a new control scheme for a three-phase split DC-link capacitor inverter as an AC power supplies. The proposed control method can maintain the balanced sinusoidal output voltage under unbalanced and nonlinear load conditions. The validity of the control method has been verified by simulation results.

• 전력전자학회논문지
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• 제18권4호
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• pp.333-341
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• 2013

In this paper, a feedback linearization control is proposed to regulate the output voltages of a three-phase four-wire inverter under the unbalanced and nonlinear load conditions. First, the nonlinear model of system including the output LC filters is derived in the d-q-0 synchronous reference frame. Then, the system is linearized by the multi-input multi-output feedback linearization. The tracking controllers for d-q-0-components of three-phase line-to-neutral load voltages are designed by linear control theory. The experimental results have shown that the proposed control method gives the good performance in response to the load conditions.

• 한국기계가공학회지
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• 제21권8호
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• pp.32-42
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• 2022

Asymptotic tracking of a non-minimum phase nonlinear system has been a popular topic in control theory and application. In this paper, we propose a new control scheme to achieve asymptotic output tracking in anon-minimum phase nonlinear system for periodic trajectories through an iterative learning control with the stable inversion. The proposed design method is robust to parameter uncertainties and periodic external disturbances since it is based on iterative learning. The performance of the proposed algorithm was demonstrated through the simulation results using a typical non-minimum nonlinear system of an inverted pendulum on a cart.

• 전기학회논문지P
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• 제66권3호
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• pp.99-104
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• 2017

The three-phase four-wire power distribution system can be used to supply power to single-phase and three-phase loads at the same time. There are linear loads and nonlinear loads as single-phase loads connected to each phase. The nonlinear load generates a harmonic current during the power energy conversion process. In particular, the single-phase nonlinear load has a higher proportion of generation of the third harmonic current than the harmonics of the other orders. In a three-phase four-wire system, the third harmonic current flows through the neutral wire to the power supply side, affecting the power supply side and the line. Furthermore, the magnitude of the current flowing in the neutral line can be higher than the current flowing in the individual phase. If the neutral current is higher than the phase current, the breaker may be blocked. Therefore, it is necessary to reduce the amount of current flowing in the neutral line by harmonics. There is a method of zigzag connecting a single phase transformer by a method of reducing 3 harmonic current. In this study, the method of reducing the magnitude of the three harmonic currents flowing through the zigzag wire by comparing the polarity and the negative polarity characteristics of the single phase transformer was compared through measurement and simulation.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.497-504
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• 2002

The characteristics of harmonic phase angles and phase angle differences contained in earthquake ground motions such as El Centre 1940 NS, Taft1 1952 NS, Hachinohe 1968 NS and Mexico 1985 are figured, which have been mostly overlooked in contrast with the importance placed on harmonic amplitudes. Recently, performance based design method is used for seismic design and seismic retrofitting, which needs nonlinear response analysis, there must be earthquake ground accelerations which contain the phase angle and the phase angle difference characteristics of the zone considered to be constructed building structures. To make clear the importance of phase angle differences, 4-earthquake ground motions are normalized by 200 gal and nonlinear response characteristics of normalized 4-earthquake ground motions are compared.

• 대한기계학회논문집B
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• 제28권11호
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• pp.1398-1406
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• 2004

The nonlinear signals from an impedance meter for the area average void fraction in two-phase flow have been analyzed to construct a phase space trajectory. The pseudo phase space was constructed with the time delay and proper dimensions. The time delay and the embedding dimension were chosen by the average mutual information and by the false nearest neighborhood, respectively. The attractor-density-map of projected states was used to produce the two dimensional probability distribution functions (2D-PDF). Since the developed 2D-PDF showed clear distinction of the flow patterns, the flow regime identification was made with three rules and with the 2D-PDF. Also, the transition criteria of Mishima-Ishii agree well with the present results.

• Journal of the Optical Society of Korea
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• 제20권2호
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• pp.228-233
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• 2016

In this paper, we propose a nonlinear maximum average correlation height (MACH) filter for information authentication of photon counting double random phase encryption (DRPE). To enhance the security of DRPE, photon counting imaging can be applied because of its sparseness. However, under severely photon-starved conditions, information authentication of DRPE may not be implemented successfully. To visualize the photon counting DRPE, a three-dimensional imaging technique such as integral imaging can be used. In addition, a nonlinear MACH filter can be utilized for helping the information authentication. Therefore, in this paper, we use integral imaging and nonlinear MACH filter to implement the information authentication of photon counting DRPE. To verify our method, we implement optical experiments and computer simulation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1496-1499
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• 1996

A nonlinear tracking control technique developed for the control of nonlinear systems has been applied to the autopilot design of missile system. The difficulties in the application of inversion based control methods such as input-output feedback linearization and sliding mode control due to nonminimum phase characteristics are discussed. To avoid the stability problem associated with unstable zero dynamics, the input-output feedback linearization is applied with output-redefinition method to normal acceleration control. The output-redefinition method gives an indirect way to apply the nonlinear controls to nonminimum phase plants by redefining the plant output such that the tracking control of the modified output ensures the asymptotic tracking of the original output. The numerical simulation shows satisfactory results both for nominal and for slightly perturbed missile systems adopting the sliding mode control technique. However, the robustness problem in this method is briefly investigated and verified with the simulation.