• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.11
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• pp.1423-1433
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• 2018

Recently, a permanent magnet synchronous motor of middle and small-capacity has high torque, high precision control and acceleration / deceleration characteristics. But existing control has several problems that include unpredictable disturbances and parameter changes in the high accuracy and rigidity control industry or nonlinear dynamic characteristics not considered in the driving part. In addition, in the drive method for the control of low-vibration and high-precision, the process of connecting the permanent magnet synchronous motor and the load may cause the response characteristic of the system to become very unstable, to cause vibration, and to overload the system. In order to solve these problems, various studies such as adaptive control, optimal control, robust control and artificial neural network have been actively conducted. In this paper, an incremental encoder of the permanent magnet synchronous motor is used to detect the position of the rotor. And the position of the detected rotor is used for low vibration and high precision position control. As the controller, we propose augmented state feedback control with a speed observer and first order deadbeat disturbance observer. The augmented state feedback controller performs control that the position of the rotor reaches the reference position quickly and precisely. The addition of the speed observer to this augmented state feedback controller compensates for the drop in speed response characteristics by using the previously calculated speed value for the control. The first order deadbeat disturbance observer performs control to reduce the vibration of the motor by compensating for the vibrating component or disturbance that the mechanism has. Since the deadbeat disturbance observer has a characteristic of being vulnerable to noise, it is supplemented by moving average filter method to reduce the influence of the noise. Thus, the new controller with the first order deadbeat disturbance observer can perform more robustness and precise the position control for the influence of large inertial load and natural frequency. The simulation stability and efficiency has been obtained through C language and Matlab Simulink. In addition, the experiment of actual 2.5[kW] permanent magnet synchronous motor was verified.

• Journal of Plant Biology
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• v.5 no.3
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• pp.1-4
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• 1962

A district (Sae-Bong) and 13 district (Sae-Jang Dong) grassland could be divided into four type of Community: Miscanthus-Community, Glyceria-Community, Festuca-Community, and Plantago-Community. Chose 17 or 20 stands from each district A and B and calculated F.I. with the Curtis method, finally vegetational continuum could be recognized while discontinuous boundary line of species distribution could not be recognized. As a rule the distributional curve of species was binominal or bell shaped. It had a distribution pattern peculiar to itself. As to the relationship of cattles' density and vegetation. I found that the tendency of F.I. moving from small to large paralleled that of disturbance-pressure from weak to strong. Found that the more the steepness of environmental factors be controlled by a rule " from large to small", the more F.I. might be controlled by a rule "from small to large" and that pH, soil-moisture-content, loss on ignition was in relation with the steepness. with the steepness.

• Journal of Navigation and Port Research
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• v.42 no.2
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• pp.87-96
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• 2018

A trajectory control system plays an important role in controlling motions of marine vehicle when a series of way points or a path is given. In this paper, a sliding mode control (SMC)-based trajectory tracking controller for marine vehicles is presented. A small-sized unmanned ship is considered as a control object. Both speed and heading angle of a ship should be controlled for tracking control. The common point of related researches was to separate ship's speed and heading angle in control methods. In this research, a new control law from a general sliding mode theory that can be applied to MIMO (multi input multi output) system is derived and both speed and heading angle of a ship can be controlled simultaneously. The propulsion force and rudder force are also applied in modeling stage to achieve accurate simulation. Disturbance induced by wind is also tackled in the dynamics considering robustness of the proposed control scheme. In the simulation, we employed a way-point method to generate ship's trajectory and applied the proposed control scheme to ship's trajectory tracking control. Our results confirmed that the tracking error was converged to zero, thus demonstrating the effectiveness of the proposed method.

• Journal of Power System Engineering
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• v.21 no.1
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• pp.30-36
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• 2017

In robot industries, the request to obtain a high efficiency and accurately controlled electric actuator has been growing. Nevertheless, the effectiveness of electric actuators is significantly affected by the presence of factors such as nonlinearity, uncertain disturbance and unknown dynamics. Therefore, it makes difficult to derive an exact mathematical model of the controlled system. In this paper, a new method for easily recognizing and regenerating robot motions used in small size industries such as painting and welding parts is proposed. Instead of modeling the entire dynamic motion of the robot system, this method is based on the procedure of modeling and controller design for every arm individually. The proposed method does not require complex model and control system such that it gives easy working process to the small size industries. Based on this fact, in this research, the model and PID controller for every arm of the 3 DOF robot system are obtained separately. Some experimental results are implemented to validate the effectiveness of the proposed method.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.04a
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• pp.126-130
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• 2000

In this study, flutter characteristics of a composite wing have been studied for the variation of laminate angles in the subsonic, transonic and supersonic flow regime. The laminate angles are selected by the aspect of engineering practice such as 0, $\pm$45 and 90 degrees. To calculate the unsteady aerodynamics for flutter analysis, the Doublet Lattice Method(DLM) in subsonic flow and the Doublet Point Method(DPM) in supersonic flow are applied in the frequency domain. In transonic flow, transonic small disturbance(TSD) code is used to calculate the nonlinear unsteady aerodynamics in the time domain. Aeroelastic governing equation has been solved by v-g method in the frequency domain and also by Coupled Time-Integration Method(CTIM) in the time domain. from the results of present study, characteristics of free vibration responses and aeroelastic instabilities of a composite wing are presented for the set of various lamination angles in the all flow range.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.2031-2042
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• 2017

In this paper, a novel traffic flow control method based-on ramp metering and speed regulation using an adaptive sliding mode control (ASMC) method along with a deadzoned parameter adaptation law is proposed at a stochastic macroscopic level traffic environment, where the influence of the density and speed disturbances is accounted for in the traffic dynamic equations. The goal of this paper is to design a local traffic flow controller using both ramp metering and speed regulation based on ASMC, in order to achieve the desired density and speed for the maintenance of the maximum mainline throughput against disturbances in practice. The proposed method is advantageous in that it can improve the traffic flow performance compared to the traditional methods using only ramp metering, even in the presence of ramp storage limitation and disturbances. Moreover, a prior knowledge of disturbance magnitude is not required in the process of designing the controller unlike the conventional sliding mode controller. A stability analysis is presented to show that the traffic system under the proposed traffic flow control method is guaranteed to be uniformly bounded and its ultimate bound can be adjusted to be sufficiently small in terms of deadzone. The validity of the proposed method is demonstrated under different traffic situations (i.e., different initial traffic status), in the sense that the proposed control method is capable of stabilizing traffic flow better than the previously well-known Asservissement Lineaire d'Entree Autoroutiere (ALINEA) strategy and also feedback linearization control (FLC) method.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.1
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• pp.58-63
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• 2010

A new contact force estimation technique is proposed. Keeping the contact force at a certain level between finishing tool and the object is essential since the quality of the finished surface is very sensitive to the contact force during the finishing process. However, the contact force measurement cannot be obtained by simply installing load cells under machine table or in the middle of tool linkage. The reason is that the weight of the machine table and the tool linkage are much heavier than the force to be measured. To that end, a method for estimating disturbance is proposed for a system that is similar to the mechanism of the finishing machine, and the same method is applied to estimate the contact force of the brush-type finishing machine. To verify the effectiveness of the proposed method, a small scale test set-up has been built and the method has been tested.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.162-166
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• 1990

This paper proposes a new method of the state reduction in dynamic equations of generators in large electric power system stability analysis. This method assumes study groups whose state trajectories we are interested in, coherency groups whose state trajectories are similar to the other state trajectories of generators in the same coherency group by a certain disturbance. By the weighted sum or the other method, the states of generators in one coherency group can be reduced to the equivalent states of an equivalent generator. This method is shown to be highly efficient in reducing the number of states with small error by the result of case study presented latter part of this paper.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.77.6-77
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• 2001

R/C helicopter has been used to several fields of military affairs, investigation, searching and toys because it has small size, hovering and vertical take-off characteristics etc. Therefore it needs more realizable control method. The paper introduces simulation and experimental results for control of a helicopter training simulator by self tuning control method. It is assumed that the helicopter is operated at the state of hovering motion and the model is induced. The self tuning control method incorporates the concepts of the well known internal model principle and annihilator polynomial for reference input and disturbance. The controller design is separated into two cases that the plant parameters are known or not. To realize ...

• Geotechnical Engineering
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• v.11 no.2
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• pp.19-28
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• 1995

Based on the various test data acquired in the field, the large pressure chamber and the small pressure chamber, uplift behaviors and method of determining the ultimate uplift capacity of pile driven in small pressure chamber were studied. After uplift pile experienced 2 or 3 sudden slip due to increase of uplift load, complete pullout failure was occurred. Thus, it appears that the ultimate uplift capacity could be identified as the load at displacement where first slip occurs. The ultimate uplift capacity might be determined in every test and the disturbance after first uplift test could be recovered by adding one blow of the drop hammer, which had to depend on the model pile capacity.