• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2003.08a
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• pp.259-269
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• 2003

The necessary of predicting changes in tidal regime that would caused by large coastal engineering developments has been led to increased numerical modeling of tides on the continental shelf since 1970s (Flather, 1976; Choi, 1978; Greenberg, 1979). (omitted)

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.248-249
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• 2000

최근 "혼돈제어"라는 몇 가지 방식이 증명되어 여러 시스템에서 혼돈스런 출렁임을 제거하게 되었다. 처음으로 OGY(Ott Grebogi Yorke) 방법에 기초를 둔 Occasional Proportional Feedback(OPF) 방식이 Roy에 의해 고체레이저 system 에 적용되었다$^{(1)}$ . 또 High Frequency Injection(HFI) 방식으로도 혼돈을 제어할 수 있음이 발표되기도 했다$^{(2),(3)}$ . 우리의 실험에서는 단일모드로 발진하는 Nd:YAG 레이저에서 일어나는 혼돈현상을 관측하려 한다. (중략)

• Korean Journal of Optics and Photonics
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• v.2 no.3
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• pp.153-157
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• 1991

We report an analysis on the stability properties of external cavity semiconductor lasers exposed to strong feedback from an external grating. The frequency range of stable single mode oscillation is found to depend on the offset between the resonance frequency of the solitary laser and the frequency of maximum reflection from the grating.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.442-445
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• 1995

This paper presents the position tracking control of a laser scanning mirror system in which piezoelectic actuator is incorporated. Using the shear mode of the piezoelectric actuator,angular oscillation of a laser scanning mirror is derived. Torsion bar is rhen designed and attached to the piezoelctric actuator in order to magnify the amplitude generated by the actuator. Finite element modeling and analysis are essntial for designing the piezoelectic actuator. The torsional resonance mode of the piezoelectric actuator is found from the model analysis of the actuator and the mechanical shear is matched with the driving frequency. Transfer function between the electrical excitation and the mechanical shear deformation at resonance frequency is found form the response of the actuator calculated by the finite element analysis and the governing equation of the system is derived from d'Alembert's principle. Tracking control performance for desired trajectory which is, in fact, sinusoidal curve is presented in order to demonstrate the validity of the proposed system.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.12
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• pp.616-623
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• 2003

Conventional P/PI speed controller of today's servo drives should be manually tuned the controller switching set-point by trial-and-errors, which may translate the drive system down-time and loss of productivity. The adjustable drive performance is heavily dependent on the quality of the expert knowledge and becomes inadequate in applications where the operating conditions change in a wide range, i.e., tracking command, acceleration/deceleration time, and load disturbances. In this paper, the demands on simple controls/setup are discussed for industry servo drives. Analyzing the frequency content of motor torque command, P/PI control mode switching is automatically performed with some prior knowledge of the mechanical dynamics. The dynamic performance of the proposed scheme assures a desired tracking response curve with minimal oscillation and settling time over the whole operating conditions. For comprehensive comparison of traditional P/PI control scheme, extensive test is carried out on actual servo system.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.722-725
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• 1996

This paper presents a new control strategy for the position and force control of a flexible manipulator. The governing equation of motion of a two-link flexible manipulator which features a piezoceramic actuator is derived via Hamilton's principle. The control torque of the motor to command desired position and force is determined by a sliding mode controller. This controller is formulated to take account of parameter uncertainties and external disturbances. During the commanded motion, undesirable oscillation is actively suppressed by applying a feedback control voltage to the piezoceramic actuator. Consequently, an accurate compliant motion control of the flexible manipulator is achieved. Computer simulations are undertaken in order to demonstrate the effectiveness of the proposed control methodology.

• Journal of KSNVE
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• v.6 no.2
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• pp.187-196
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• 1996

A new control strategy to actively control the vibration of a very flexible single link manipulator is proposed and experimentally realized. The control scheme consists of two actuators; a motor mounted at the beam hub and a piezoceramic bonded to the surface of the flexible link. The control torque of the motor to produce a desired angular motion is firstly determined by employing a sliding mode control theory on the equivalent rigid dynamics. The torque is then applied to the flexible manipulator in order to activate the commanded motion. During the motion, underirable oscillation is actively suppressed by applying a feedback control voltage to the piezoceramic actuator. Consequently, the desired tip position is favorably accomplished without vibration. Measured control responses are presented in order to demonstrate the efficiency of the proposed control methodology.

• Transactions on Electrical and Electronic Materials
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• v.18 no.5
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• pp.303-309
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• 2017

The flexible AC transmission system (FACTS) provides a new advanced technology solution to improve the flexibility, controllability, and stability of a power system. The unified power flow controller (UPFC) is outstanding for regulating power flow in the FACTS; it can control the real power, reactive power, and node voltage of distribution networks. This paper investigates the performance of the UPFC for power flow control with a series of step changes in rapid succession in a power system steady state and the response of the UPFC to distribution network faults and islanding mode. Simulation was carried out using the MATLAB's simulink sim power systems toolbox. The results, which were carried out on a 5-bus test system and a 4-bus multi-machine electric power system, show clearly the effectiveness and viability of UPFC in rapid response and independent control of the real and reactive power flows and oscillation damping [6].

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.1162-1164
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• 1997

This paper presents a power system stabilizer(PSS) using sliding mode-model following(SM-MF) including closed-loop f:edback(CLF) and compares the SM-MF PSS without CLF with that including CLF. The aim of this SM-MF PSS including CLF is to damp the low-frequency oscillation by using CLF and then is to obtain asymptotic tracking error between the reference model state and the plant state.

• Journal of the Optical Society of Korea
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• v.13 no.4
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• pp.423-427
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• 2009

The results of the experimental and theoretical studies conducted on terahertz filtering using two parallel-plate waveguides (PPWGs) are presented herein. The first PPWG with 355 ${\mu}m$ plate separation generates 4 THz bandwidth TM modes ($TM_0,\;TM_2,\;and\;TM_4$), whereas the second PPWG with 100 ${\mu}m$ plate separation operated the THz filter for the generated TM modes with 1.5 THz cutoff frequency. The outgoing THz wave of the two PPWGs was truncated until 1.5 THz, and the system was operated using a high-pass THz filter. The absorption and dispersion of the combined TM and TE modes for the filtering system were calculated. The theoretical calculation and measurement results for the cutoff and oscillation frequency in the spectrum domain agreed well.