• Transactions of The Korea Fluid Power Systems Society
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• v.1 no.3
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• pp.14-19
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• 2004

The Direct Drive Valve used in this study contains a pressure-feedback-loop in itself, then it can eliminate nonlinearity such as the square-root-term in flow rate calculation and the change of bulk modulus of hydraulic oil. In this study, assuming that the dynamic characteristic of the DDV is modelled as a first order lag system, an parameter identification method using the input data and the output data is applied to obtain DDV's mathematical model. Then, a state feedback controller was designed to implement the force control of hydraulic system, and the control performance was evaluated.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.7
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• pp.337-345
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• 2006

This paper proposes a high speed SRM drive system for blower application with a new 4-level inverter and precise excitation position generator. For a high speed blower, a proper inverter and control method are proposed and the output characteristics are analyzed. In order to get a fast build-up and demagnetization of excitation current, a 4-level inverter system is proposed. The proposed 4-level inverter has additional charge capacitor, power switch and diode in the conventional asymmetric converter. The charged high voltage is supplied to the phase winding for fast current build-up, and demagnetization current is charged to additional capacitor of the 4-level inverter. In addition, a precise excitation position generator can reduce turn-on and turn-off angle error according to sampling period of digital control system. The proposed high speed SRM drive system is verified by computer simulation and experimental results.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.42-45
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• 2002

In the two-mass motor drive system driving a load through a flexible shaft or transmission system, a shaft torsional vibration is often generated. The overshoot of the motor drive system easily causes vibration. In this case I-PD controller has been generally used in speed control, because of the simplicity of structure. This paper using an analytical pole assignment design, proposes the overshoot formulas, and the settling time formula. The objective of this paper is to provide a design method of I-PD controller by using overshoot formulas, and settling time formula. The simulation results show that we can design the controller with desired overshoot and settling time.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.3-8
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• 1994

This paper presents a practical method of measuring the cutting force milling process by sensing the feed-drive servo motor current,avoiding the use of a dynamomenter. The relation between the cutting force and the servo motor currents is obtained after the feed-drive system of machining center is modelled. In order to measure the cutting force indirectly, the cutting force in the feed-drive system is regrared as a disturbance, and a disturbance estimator is designed using Kalman filter. A horizontal type machining center is used in the experimental study. A comparison is made between the cutting force measured from the dynamometer and the servo motor current.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.356-360
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• 1990

This paper is an application of Modern control Theory to the control of a current-source inverter (CSI) fed Induction Motor Drive System. A Linear Quadratic-Gaussian (LQG) scheme is developed, in which the Kalman Filter is tuned for high robustness by a method due to Doyle and Stein(8). The design is carried out for a sample system and the robustness by analysis and computer simulation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.214-217
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• 2002

Micro Surface Electrochemical Machining has traditionally been used in highly specialized fields such as those of the aerospace and defense industries. It is now increasingly being applied in other industries where parts with difficult-to-cut material, complex geometry and tribology such as compute. hard disk drive(HDD) are required. Pulse Electrochemical Micro-machining provides an economical and effective method for machining high strength, high tension, heat-resistant materials into complex shapes such as turbine blades of titanium and aluminum alloys. Usually aluminum alloys are used bearings to hard disk drive in computer. In order to apply aluminum alloys to bearing used in hard disk drive, this paper presents the characteristics of Micro Surface Electrochemical machining for aluminum alloy.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2281-2284
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• 2008

The purpose of this paper is to develope the drowsiness-drive perception system which judges drowsiness driving based on drivers' eye region using single vision system. To do this, first, we use the Haar-like feature and AdaBoost learning algorithm for detecting the features of the face region. And we measure the eye blinking frequency and eye closure duration from these feature data. And then, we propose the drowsiness-drive detection algorithm using the eye blinking frequency and eye closure duration. Finally, we have shown the effectiveness and feasibility of the proposed method through some experiments.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.30-32
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• 2005

In this paper, voltage control strategy for maximum torque operation of stator flux-oriented induction machine drive in the field-weakening region is proposed. In a conventional stator flux-oriented (SFO) induction machine drive system of the maximum torque capability cannot be obtained. The field-weakening method is used to vary the stator-flux reference in proportion to the inverse of the rotor speed. The proposed algorithm, based on the voltage control strategy, ensures the maximum torque operation over the field-weakening region. The proposed algorithm, voltage control strategy for maximum torque operation of capability, which is insensitive to the variation of machine parameters In the field-weakening region. The proposed algorithm is verified by simulation.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.215-219
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• 2005

In this paper, a novel motor control method is proposed to improve the performance of sensorless drive of BLDC motors. The unknown input (back-EMF) is modelled as the additional state of system in this paper. Taking into account the disturbance adopted by the back-EMF, the observer can be obtained by the augmented system equation. An algorithm to detect the back-EMF of the BLDC motor using the state observer is constructed. As a result, the novel sensorless drive of BLDC motors that can strictly estimate rotor position and speed is proposed.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.6
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• pp.554-560
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• 2011

Single-frequency induction heating equipment caused by a hardening heat treatment process of the double investment in the issue and allow the heat treatment process in order to shorten the time from one process to work simultaneously on two kinds of processes that allow Simultaneous Dual Frequency(SDF) drive scheme technology are described. In this paper, we propose a dual way to drive a simultaneous dual-frequency drive scheme has been implemented. Through simulations and experiments, we can obtain the validity of the proposed inverter for dual-frequency control and power control.