• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1347-1352
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• 2009

Magnetic force driven six degree-of-freedom active vibration isolation system is developed. The velocity sensor using an electromagnetic principle that is commonly used in the vibration control is investigated since its phase lead characteristic causes an instability problem for a low frequency vibration. A lag-type compensator is adopted to reduce the phase lead and the stability test is performed by using a Bode analysis. The performance of the AVIS is validated by comparing with the passive isolation system by using the frequency responses.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.6
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• pp.888-894
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• 1986

In this paper, a phase locked loop control system is designed to have high performance and stability in a 2-phase bifilar winding PM step motor. The BODE diagram analysis method is used to improve the stability and dynamic characteristic of the closed loop control system. Also, a PLL servo is used to accomplish high-precision speed and to attain smooth ness. In applying the PLL control to the step motor, a new design method is suggested to solve the control problem which occurs as a result of the limited maximum acceleration of the step motor. A simple design method is suggested without using the complicated multi-step characteirstic of the step motor in constant voltage driving. Computer simulation results agree clorelg with experiments, indicating that the PLL servo system of the step motor designed is very useful.

• Journal of Power System Engineering
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• v.18 no.5
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• pp.28-34
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• 2014

This paper deals with optimum PI controller design using genetic algorithm to improve control performance and robustness for an oil cooler system. The optimum PI gain was found to minimize an object function, integrated absolute error, and to satisfy control design specifications such as overshoot and settling time based on practical transfer function of the oil cooler system. The control performance and robustness were investigated by comparing indicial responses and Bode diagram analysis with respect to three kinds of PI gains obtained from different gain decision manners. Moreover, the robustness against to input disturbances, sinusoidal wave form and abrupt single pulse, was evaluated. The computer simulation results showed that the suggested optimum gain can establish desirable control performance and strong robustness with easy design process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.185-189
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• 1992

This paper prsents an end-point control of a one-link flexible arm with a payload by using closed loop control. Tip position of arm is shifted by the base motion according to DC servomotor, whivh is driven by a feedback signal composed of the tip displacement and the estimated tip velocity. The shifting problem of the arm from initial position to desired position is considered by the variation of the displacement gain Gd and velocity agin Gv. Theoretical results are obtained by applying the method of the Laplace transform to the governing equations and the method of numerical inversion. This system is composed of a flexible arm with payload, DC servomotor, and a ballscrew mechanism. The flexible arm is mounted on a mobile stage driven by a servomotor and ballscrew. In controlling the tip displacement of flexible arm, the fundamental bode vibration is supressed more rapidly with an increase of the velocity feedback gain Gv and the feedback displacemenmt gain Gd. Theretical responses are approximately in good agreement with those obtained experimentally.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.992-993
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• 2015

본 논문은 양방향 전류 제어를 위한 고안정 전류원 전원 장치의 영점 전류 부근에서의 PWM 방법과 출력 필터 설계를 위한 가이드 라인에 대해 기술 하였다. LCR 출력 필터의 공진점에서 전압의 크기를 줄이기 위한 댐핑 저항의 크기에 따라 Bode plot을 통해 임피던스와 전달함수의 주파수 특성을 분석하고 낮은 Q-factor를 갖는 출력 필터의 댐핑 저항 크기를 확인 하였다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.66-69
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• 2008

In this paper, The author present a load current feed-forward compensator by method that improve voltage controller of Step-down Chopper to get stable output voltage to sudden change of load current. To confirm the characteristicsof a presented load current feed -forward compensator compared each transfer function of whole system that load current feed-forward compensator is added with transfer function of whole system that existent voltage controller is included using Mason gains formula in Root locus and Bode diagram. As a result the pole of system is improved, extreme point of the wave and system improves, and size of peak value and phase margin of break frequency in resonance frequency confirmed that is good. Therefore, presented control technique could confirm that reduce influence by perturbation and improves stationary state and dynamic characteristics in output of Step-down Chopper.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.5
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• pp.482-488
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• 2009

Dancer system is typically used equipment for attenuation of tension disturbances. In industrial converting machines, a composite type of dancer system is applied which is mixture of active and passive dancer. It includes feedback position control loop of roll with pendulum dancer and its characteristics is different from passive and active one. In this paper, a mathematical model of the pendulum dancer was derived including PI position feedback controller and it was analyzed by using a pole-zero map and bode plot under various conditions. It was found out that velocity, length of span and inertia were associated with the performance of regulation. It was suggested that the length of upstream span should be greater than that of the downstream and the inertia should be smaller for improvement of the performance. The results can be used for design guidelines of the industrial dancer system.

• 전기의세계
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• v.15 no.3
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• pp.8-14
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• 1966

제어이론은 안정성판별을 중심으로 발달하여 왔으며 제어공학자체가 하나의 기술인 이상 안정판별법은 가능한 한 그 표현이 간단명료한 것을 요구하게 되었다. 과거에 연구되어 온 여러가지 안정판별법등은 즉 Routh 및 Hurwitz에 의한 방법, Nyquist 및 Michailov에 의한 방법 등, 정성적방법과 Bode 및 Nichols에 의한 방법, Evans에 의한 Root locus법, Bilharz 및 Frank에 의한 방법, Tsypkin 및 Bromberg에 의한 방법 등, 정량적인 취급방법 등이 연구발표되어 제어계통의 설허 및 해석에 이용되어왔다. 그러나 설계자들은 제어계통의 안정성판별에만 흥미를 갖는것이 아니라 안정도판별 즉 계통응답에 더 주의를 기우리게 된다. 특히 실시간응답에 대하여 명확한 해답을 요구한다. 본 고에서는 두개의 Parameter Plane Method의 기초를 다룬 것으로 특성방정식의 계수중에서 임의의 두개를 Parameter로 하는 것이며 과도해답 및 주파수응답을 요하는데 편리하나 임의의 두개의 계수만을 Paraweter로 하므로서 두개 이상의 Parameter가 존재하는 경우에는 부적당하다. 또한 우리나라에서도 시도된 바가 있다. 이와같은 것을 개선한것이 Siljak의 Parameter Plane Method이며 이것을 여기에 소개하고자 한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.234-238
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• 2003

Ultra small optical drive or PCMCIA type needs a focusing actuator because or applying Blue Laser and enhancing compatibility according to disk physical specification. Based on this need, this paper presents a novel focusing actuator adapted for ultra small optical drive of PCMCIA type. The focusing actuator using Lorenz force generated consists of coil, magnets and plate springs of pivoting. The design issues of the focusing actuator are the flexibility to focus direction, the rigidity to track direction and the higher natural mode of the moving part. For settling these Issues, this paper present mechanical design, computer simulations and test results of the realized focusing actuator. Finally, suitability and usefulness of the focusing actuator was demonstrated by the comparison of simulations and test results in a view of the possibility adapted for ultra small optical drive.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.6
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• pp.845-851
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• 1986

This Paper presents micro-computer simulation programs for a pneumatic control system. The simulation programs have been written in BASIC language which is suitable for 6502CPU with 48KB memory and consist of 11 programs which describe the time response and frequency response of the pneumatic actuation system. This simulation package is stored in 51/4 inch floppy diskette. The user requires no simulation expertise on the part of designer. As the result of using this simulation programs for the pneumatic control system with stabilizing tank, it has shown that the response time of the system using air as working medium takes more time to be settled but relatively stable rather than the system using helium.