• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.8
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• pp.2501-2507
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• 1996

In this paper actively controlled air bearing is investigated to overcome the defects of air bearing such as low stiffness and damping coefficients. The actively controlled air beairng is composed of an air bearing, a gap sensor, a controller, and a piezo actuator. By controlling the position of air bearing with piezo actuator, the position of floating object is controlled. In this study the proportional-Integral-Derivative controller is employed. Active air bearing is investigated numerically and experimentally. There is good agreement between the simulation and the experimental results. It is shown that the stiffness and damping characteristics and positioning experimental results. It is shown that the stiffness and damping characteristics and positioning accuracy of air bearing can be improved by means of adopting actively controlled air bearing.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.413-418
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• 1998

We often use induction motor in the hard environment including vibration and high ambient temperature, or in maintenance free operation, because induction motor has durable and simple structure. However, when we use it as servo actuator or accurate speed control motor, we have to equip sensor such as encoder and tachogenerator with the motor control system. And generally those sensor's abilities against bad environment are less than the induction motor itself, So if we can remove these sensors from the system, it'll have more environmental resistance, and the cost will also be reduced. Actually this removal has been achieved in limited field. However, that needs complex calculations and a certain elapse time for data processing. In our study, we intended to estimate the rotational speed from the motor current instead of speed sensor, easily and rapidly in comparison to former methods.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.4
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• pp.247-252
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• 2016

In this paper, we propose a new defect detection technology for micro-defect on the surface of steel products. Due to depth and size of microscopic defect, slop of surface and vibration of strip, the conventional optical method cannot guarantee the detection performance. To solve the above-mentioned problems and increase signal to noise ratio, a novel retro-schlieren method that consists of retro reflector and knife edge is proposed. Moreover dual switching lighting method is also applied to distinguish uneven micro defects and surface noise. In proposed method, defective regions are represented by a black and white pattern. This pattern is detected by a defect detection algorithm with Gabor filter. Experimental results by simulator for sample defects of cold rolled steel show that the proposed method is effective.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.6
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• pp.568-573
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• 2007

Environmental information (temperature, humidity, vibration, $CO_2$, gas leakage, etc.) of building is an essential item to manage and monitor a building. For intelligent building, it is necessary to get temperature and illumination information to save energy and crack information to prevent structural problems. Moreover, temperature and gas leakage information to alarm a tire precaution, or humidity information to maintain comfortable environment. However, there have not been many researches on systems for gathering environmental information and building maintenance due to high costs. In this paper, wireless sensor network technology is applied to collecting building environmental information. Wireless sensor network is one of the latest issues and has low-power consumption, low-cost, self-configuration features.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.1
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• pp.33-38
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• 2003

This paper describes control principles of the piezoelectric ultrasonic motor which is operated by the ultrasonic vibration generated by the piezoelectric element. The piezoelectric ultrasonic motor has excellent characteristics such as compact size, noiseless motion, low speed, high torque and controllability, and has been recently applied for the practical utilization in industrial, consumer, medical and automotive fields. In this paper, the design of two-phase push-pull inverter for driving the piezoelectric ultrasonic motor is described, and a new control method of automatic resonant frequency tracking using PLL(Phase-Locked Loop) technique is mainly presented. the experimental results by this inverter system for driving the piezoelectric ultrasonic motor are illustrated herein. The inverter system with PLL technique improved the speed stability of the piezoelectric ultrasonic motor.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.2
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• pp.200-206
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• 1991

In this paper, an output feedback is used to reduce the effect of the vibration in the control of a flexible one-link robot arm. A PD control method with a time varying gain is proposed to improve the performance of the system in tip deflection and settling time for the step reference input. By making the change of feedback gain smoothly, th input torque can be made smooth. When there is a payload with unknown mass, an interpolation method which uses the inrehgrated value of the transient response of the hub angle is proposed for the estimation of teh payload mass. This method can be used when the reference input is known and we can get highly accurate estimate for the unknown payload. It is also demonstrated that flexible one-link arm can be controlled prettry accurately by an output feedback in a noisy environment without knowing the mass of the payload.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.103-106
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• 1996

In this paper, we proposed the design and algorithm of force reflection joystick which control mobile robot as a rehabilitation assistance system. The disabled persons are poor at joystick control because of hand vibration and clumsiness in operating it. These problems bring tasks which concerned with operator's safety So there is required technique which prevent collision with wall or obstacles. One of these solution is force reflection joystick which disturb that robot is closed to the wall. To confirm this way, we experimented and simulated with force reflection joystick which attached torque controller.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.7-11
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• 2002

This paper proposes an APF(Active Power Filter) with WRIM(Wounded Rotor Induction Motor) controlled by sliding mode which can compensate harmonic currents generated in a power system. As non-linear loads increase gradually in industry fields, harmonic current generated In the electric power network system also increases. Harmonic current makes a power network current distorted and generates heat, vibration and noise In the power machinery, Many approaches have been applied to compensate harmonic currents generated in the power system. Among various control strategy, in this paper, a sliding mode controlled systems is designed and evaluated. This is a flywheel compensator based on secondary excitation of WRIM(wounded rotor induction motor) with SMC(sliding mode controller). The proposed system uses a flywheel as an energy storage device. The designed control scheme is verified through simulation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.617-624
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• 2008

This paper proposes design and implementation of wind turbine simulators which incorporate the turbine dynamic characteristics. At first, the turbine output characteristic in steady state is modelled as a function of wind speed and then dynamic characteristics are modelled such as pitch angle control, torsional vibration, tower shadow effect, wind shear effect, and inertia effect. In addition, a wind speed simulator is developed which can generate the real wind speed pattern. The wind turbine simulator is implemented with 3[kW] M-G set(cage-type induction motor coupled with doubly-fed induction generator) at laboratory.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.98-100
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• 1995

This paper deals with development of high torque and high accurate stepping motor and control system which is adopted heavy equipment engine speed control. In the process of development, only pure domestic technics is involved, all the parts are supplied in domestic industries, and successfully accomplished to mass production. In order to confirm product liability, circumferential test,such as vibration test impact test,thermal test,and field test are thoroughly fulfilled.