• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.76-85
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• 1997

The understeer characteristics of four wheel steering system(4WS system) in a high speed region have a negative effect upon the yaw velocity, leading to a decrease in the handling ability of vehicle. As a result, even if the side slip angle of vehicle can be kept up a minimum, a driver must compensate a decrease in yaw velocity by increasing the steering wheel angle in order to track the desired vehicle path. In this study, to keep the side slip angle of vehicle at zero and achieve a suitable yaw velocity in vehicle motion, a full active 4WS system(FA 4WS system) with actively steerable front and rear wheels is presented based on a nonlinear vehicle model and a model following control of yaw velocity. And the analysis results show the fat that, besides the excellent stability of vehicle, the FA 4WS system is able to realize better handling performance of vehicle than the previous 4WS systems in the high speed region.

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.4
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• pp.341-346
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• 2002

When a construction company builds a high structure. many piles should be driven into the ground by a hammer whose weight is 7,000 kg in order to make the ground under the structure safe and strong. So. it is essential to determine whether a pile is penetrated into the ground enough to support the weight of the structure since ground characteristics at different locations are different each other. This paper proposes a visual measurement system for pile rebound and penetration movement including vibration using a high-speed line-scan camera and a specially designed mark to recognize two-dimensional motion parameters of the mark using only a line-scan camera. A mark stacking white and black right-angled triangles is used for the measurement, and movement information for vertical distance, horizontal distance and rotational angle is determined simultaneously. Especially- by adopting a line-scan CCD camera whose line rate is 20 ㎑. the measurement performance of dynamic characteristics of the pile at impact instant is improved dramatically.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.6
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• pp.425-434
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• 2003

The disturbance observer(DOB) has been widely used in high speed and high precision motion control applications and the characteristics of DOB have been investigated in depth. Though most of DOB's have been implemented as the discrete-time form in digital devices, we are still short of the researches on discrete-time DOB (DDOB) in spite of rich references on continuous-time DOB. In this paper, we discuss about the disturbance rejection property and measurement noise effect of discrete-time DOB. Especially, we will focus on revealing the role of sampling time in designing the discrete-time DOB and show the validity of analysis through simulations and experiments for optical disk drive systems.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.1
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• pp.19-26
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• 2017

In this paper, we describe the design and performance of UAV system toward compact and fully autonomous quadrotors, where they can complete logistics application, rescue work, inspection tour and remote sensing without external assistance systems like ground station computers, high-performance wireless communication devices or motion capture system. we propose high-speed hovering flyght height control method based on state feedback control with image information from active camera and multirate observer because we can get image of the information only every 30ms. Finally, we show the advantages of proposed method by simulations and experiments.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.6
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• pp.826-831
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• 2007

In this paper, we proposed new method of soft-motor control which is control method allowing motor control within control stage by using EtherCAT which is real time motion control network of high speed. We also evaluated performance of the system and verified possibility and effectiveness of application into real system through experiments.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.11a
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• pp.159-167
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• 2000

During the operation of crane system in the container yard, it is necessary to control the crane trolley position so that the swing of the hanging container is minimized. Recently an automatic control system with high speed and rapid transportation is required. Therefore, we designed a controller to control the crane system with disturbances and weight change. In this paper, we present the neural network two degree of freedom PID controller to control the swing motion and trolley position. Then we executed the computer simulation to verify the performance of the proposed controller and compared the performance of the neural network PID controller with our proposed controller in terms of the rope swing and the precision of position control. Computer simulation results show that the proposed controller has better performances than neural network PID with disturbances.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.475-480
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• 2000

A new positioning mechanism with Parallel type actuator using piezoelectric material and with dual type actuators using voice coil motor (VCM) and piezoactuator is proposed for optical disk drive or near-field recording type drive, and high speed position and vibration control are investigated. Parallel type bimorph piezoactuator is used as a fine motion actuator with self-sensing technique, which allows a piezoelectric material to concurrently sense and actuate in a closed loop frame work, and positive position feedback control algorithm is adopted to further control residual vibration. For positioning control of VCM, PID control algorithm is adopted.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.142-142
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• 2000

During the operation of crane system in container yard, it is necessary to control the crane trolley position so that the swing of the hanging container is minimized. Recently an automatic control system with high speed and rapid transportation is required. Therefore, we designed a controller to control the crane system with disturbances. In this paper, Ive present the neural network two degree of freedom PID controller to control the swing motion and trolley position. Then we executed the computer simulation to verify the performance of the proposed controller and compared the performance of the neural network PID controller with our proposed controller in terms of the rope swing and the precision of position control . Computer simulation results show that the proposed controller has better performances than neural network PID with disturbances.

• Journal of Drive and Control
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• v.12 no.4
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• pp.54-59
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• 2015

Due to the tendency to use high speed pneumatic cylinders to improve productivity, cushioning devices are adopted to decelerate the piston motion of pneumatic cylinders to reduce noise, vibration, and impact. This paper presents a comparison of the cushion characteristics of a high speed pneumatic cylinder with a relief valve type cushioning device. The system parameters selected are the damping coefficient, Coulomb friction, heat transfer coefficient, and cracking pressure of the relief valve in the air cushioning device. The integral of the time multiplied square error (ITSE) is used to quantitative measure the cushioning performance to assess the effect of varying these. The cushioning performance achieved good results when the ITSE is a minimum value. In a comparison of the piston displacement and velocity with the variations in system parameters, the heat transfer coefficients are not as significantly affected as the other. Also, the cracking pressure of the relief valve is mainly affected by the pressure and temperature in the cushion chamber.

• Journal of Power System Engineering
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• v.2 no.1
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• pp.73-79
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• 1998

In practical fields, the sway of crane systems leads to extra stress to the crane structure during the transporting operation and it is in close connection with its life. Usually, when we operate the cranes with high speed and manual control, the sway motion is irreducible. In this paper, a new type of crane system is proposed to avoid the irreducible sway of the crane systems. The proposed system is composed of mechanical arm with function of anti-sway based on conventional line system. By the anti-sway arm, we can realize to prevent the sway of the container box but cannot avoid the oscillation for the overall body of the crane. So, a controller design method to solve the above stated problem must be considered. The problem is solved by adopting the velocity pattern control methods of trapezoidal and curve types and its effectiveness is proved through experimental results.