• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1322-1325
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• 1997

A new feedback control law design techniqed usign of-off thrusters for the rotational maneuver of a flexible arm is discussed in this study. a two state on-off thruster actuator is taken as a primary actuation device for theis study. The on-off thruster operation is emulated in conjunction with the conventioal minimum-time trackig control law. The actuator input region is divided into two separate parts ; one is constant input and the other is time varying tegion. the new control law has potential applicatioin for the relatively low frequency structure such as large flexible space structure being currently used in various space echnology areas.

• 조명전기설비학회논문지
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• 제19권7호
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• pp.113-121
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• 2005

본 논문에서는 오존발생장치의 전원측 파형에 포함되는 고주파수의 노이즈를 제거하고, 디지털 궤환 제어에 의해 오존 출력을 제어하기 위하여 전원장치의 출력측 LC 필터와 방전관 용량으로부터 커패시터 전압과 전류를 검출하여 2중의 제어루프를 설계하였다. 디지털 제어기의 연산지연시간을 보상하기 위하여 연산지연시간을 전원장치 플랜트의 고유한 파라미터로 가정하고, 플랜트 모델에 포함시켜 모델링 하였다. 오존발생장치의 부하변동에 따르는 과도상태 응답특성을 개선하고, 파라미터 변동에 강인한 특성을 얻기 위하여 내부 전류 모델 제어기를 제안하였다. 또한 오존발생장치용 전원장치에서 영 오차의 정상 상태를 얻기 위하여 외부 전압 제어루프를 구성하여 비례 제어기와 공진 제어기를 병렬로 연결한 비례-공진 전압제어기를 제안하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅲ
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• pp.1295-1298
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• 2003

The steam generator level in a PWR is very difficult to control particularly at low power. And the constant control gain and time value are not adaptive in steam generator level controller. In normal operation constant control gain and time value have no problem. But there is problem at low power. So variable control gains based on the temperature are required. The best control gain is decided by the experienced knowledge. A fuzzy gain tuner is used for the gain tuning. In the design of fuzzy gain-tuner processing, the experienced knowledge is employed for making fuzzy rules.

• 한국정밀공학회지
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• 제6권2호
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• pp.30-39
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• 1989

Variable structure control (VSC) systems control the state vectors using sliding regime (SR) constructed switching logic, switching plane and control law. Saturation function switching logic is used to improve the drawback which occurs in traditional sign function switching logic. Switching plane with time-varying parameter is proposed to improve the drawback which occurs in switching plane with constant parameter and it is suggested the control law which has time-varying parameter. The stability of VSC system controlled by proposed time-varying SR is discussed, and the good control behavior was shown through computer simulation using proposed SR.

• 대한기계학회논문집A
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• 제21권3호
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• pp.485-501
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• 1997

Pressure control is possible driving a simple ON/OFF 3-way valve of hydraulic servo system by pulse width modulation signal. But the pressure varies according to the duty ratio and carrier frequency and repeated on-off action induces pressure fluctuation. So equations for mean pressure and ripple amplitude are theoretically derived as a function of on/off time, the system parameters which decide the pressure characteristics are arranged and they are verified by experimental study. As the result selection criteria for the major design parameters are established and the basic strategy to suppress the unnecessary fluctuation can be provided for a hydraulic pressure control system using these type of valves.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.657-659
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• 2004

CAN is a serial communication bus for real-time controls and automations in distributed control systems. In distributed control systems, occasionally a sensor module and a controller are not in the same node and physically separated. In order for the signal from a sensor node to reach the controller node, the signal must travel through network. CAN has a certain capabilities to deal with real-time data. However, when many nodes on the networks try to send data on the same network, the arbitration mechanism to solve the data collision problem is necessary. This situation causes the time delay which has detrimental effects on the performance of the control systems. This paper proposes a method to solve the problem due to the time delay in distributed control system using CAN. Time delay is approximated to an element with a rational transfer function using Pade approximation and Mu~synthesis method is applied. Since time delay in the network is not constant, the time delay element is considered to be an uncertainty block with a bound. The proposed method is applied to the experimental system with CAN and proved to be effective.

• Journal of Power Electronics
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• 제13권2호
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• pp.197-205
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• 2013

In energy injection resonant AC-AC converters, due to the low frequency effect of the AC input envelope and the low energy injection losses requirement, the constant and steady control of the high frequency AC output envelope is still a problem that has not been solved very well. With the aid of system modeling, this paper analyzes the mechanism of the envelope pit on the resonant AC current. The computing methods for the critical damping point, the falling time and the bottom value of the envelope pit are presented as well. Furthermore, this paper concludes the stability precondition of the system AC output. Accordingly, an optimal control method for the AC output envelope is put forward based on the envelope prediction model. This control method can predict system responses dynamically under different series of control decisions. In addition, this control method can select best series of control decisions to make the AC output envelope stable and constant. Simulation and experimental results for a contactless power transfer system verify the control method.

• 제어로봇시스템학회논문지
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• 제4권4호
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• pp.420-426
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• 1998

It is the purpose of this paper to make a preliminary study on the use of repetitive control to improve velocity accuracy by eliminating repetitive disturbances caused by machining inaccuracies of the axis of rotation location. If the control system can be intelligent enough to compensate for such machining errors, then one may be able to improve the accuracy of the velocity control, or alternatively, one may maintain the same accuracy and relax the machining tolerances required. This could decrease cost significantly. Experiments are performed testing repetitive control methods on a constant speed rolling operation testbed. The experimental results show very substantial decreases in the tracking error of the system. Spectral data of the output motion are given to demonstrate the attenuation of the disturbance frequencies and harmonics, related to the bandwidth being used. It is seen that the simplest form of repetitive control which is very easily implemented, can produce striking improvement in control system performance in such belt drive rolling operations, and the learning can be accomplished in a short time.

• 한국자동차공학회논문집
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• 제10권6호
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• pp.227-233
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• 2002

A vehicle longitudinal control strategy with guaranteed string stability for vehicle stop-and-go(SG) cruise control is presented in this paper. The SG cruise control systems should be designed such that string stability can be guaranteed in addition to that every vehicle in a string of SG cruise control vehicles must track any bounded acceleration and velocity profile of its preceding vehicle with a bounded spacing and velocity error. An optimal vehicle following control law based on the information of the 1311owing distance (clearance) and its velocity relative to the vehicle ahead (relative velocity) has been used and string stability analysis has been done based on the control law and constant time gap spacing policy, A validated multi-vehicle simulation package has been shown that the string stability analysis using the approximate model of the vehicle servo-loop which includes vehicle powertrain and brake control system dynamics is valid in the design of the SG cruise control law with guaranteed string stability.

• The Korean Journal of Ceramics
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• 제5권3호
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• pp.245-249
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• 1999

A new type of nonthermal plasma reactor utilizing ferroelectric pellets is proposed to generate nonthermal plasma efficiently, which is used for simultaneous control of various pollutant gases. Electric charges stored on ferroelctric pellets by corona discharge between a corona tip and a mesh electrode provide partial electrical discharges among ferroelectric pellets. These partial electrical discharges can enhance partial discharges around the surface of ferroelectric pellets. This method utilizes wide reacting area of ferroelectric pellets and partial discharge. Positive and negative dc voltage are applied to the corona tip to generate partial discharges, and corona currents are estimated to investigate charge storage on ferroelectric pellets as function of time and charge relaxation time constants of ferroelectric pellects. As a result, charge relaxationtime, dielectric constants of ferroelectric pellets, polarity of applied voltage and applied time influence partial discharges among ferroelectric pellect.