• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.3
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• pp.352-357
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• 1996

Recently, Permanent Magnet Synchronous Motor(PMSM) drives are widely used for industrial applications due to its high efficiency and high power factor control strategy. PMSM generally have two classifications such as the SPMSM(Surface Permanent Magnet Synchronous Motors) and IPMSM(Inter Permanent Magnet Synchronous Motors). IPMSA has economical merits over SPMSM in higher speed range, mechanical robustness, and higher power rate by the geometric difference. The maximum torque operation in IPMSM is realized by the current angle control which is to utilize additional reluctance torque due to a rotor saliency. In traction, spindle and compressor drives, constant power operation with higher speed range are desirable. This is simply achieved in the DC motor drives by the reduction of the field current as the speed is increased. However, in the PMSM, direct control of the magnet flux is not available. The airgap flux can be weakened by the appropriate current angle control to demagnetize. In this paper, the control method of optimal current vector in IPMSM is described in order to obtain the maximum torque or maximum output with the speed and load variations. The applied algorithm is realized by the proto system with torque and speed control Experimental results show this approach is satisfied for the high performance servo applications. (author). 6 refs., 9 figs., 1 tab.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.1
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• pp.63-68
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• 2018

At present, ultra-precision cutting technology has been studied in Korean research institutes, focusing on development of ultra-precision cutting tool technology and ultra-precision control engineering. However, the developed technologies are still far behind advanced countries. It focuses on metals including aluminum, copper and nickel, and nonmetals including plastics, silicone and germanium which require high precision while using a lathe. It is hard to implement high precision by grinding the aforementioned materials. To address the issue, the ultra-precision cutting technology has been developing by using ultra-precision machine tools very accurate and strong, and diamond tools highly abrasion-resistant. To address this issue, this study aims to conduct ultra-precision cutting by using ECTS (Error Compensation Tool Servo) to improve motion precision of elements and components, and compensate for motion errors in real time. An IR camera is used for analyzing cutting accuracy differences depending on the heat generated in diamond tools in cutting to examine the heat generated in cutting to study cutting accuracy depending on generated heat.

• Computers and Concrete
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• v.20 no.3
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• pp.339-350
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• 2017

Dynamic behaviours of reinforced concrete (RC) bending beams subjected to monotonic loading with different loading rates were studied. A dynamic experiment was carried out with the electro-hydraulic servo system manufactured by MTS (Mechanical Testing and Simulation) Systems Corporation to study the effect of loading rates on the mechanical behaviours of RC beams. The monotonic displacement control loading, with loading rates of 0.1 mm/s, 0.5 mm/s, 1 mm/s, 5 mm/s and 10 mm/s, was imposed. According to the test results, the effects of loading rates on the failure model and load-displacement curve of RC beams were investigated. The influences of loading rates on the cracking, ultimate, yield and failure strengths and displacements, ductility and dissipated energy capability of RC beams were studied. Then, the three-dimensional finite element models of RC beams, with the rate-dependent DP (Drucker-Prager) model of concrete and three rate-dependent model of steel reinforcement, were described and verified using the experimental results. Finally, the dynamic mechanical behaviours and deformation behaviours of the numerical results were compared with those of the experimental results.

• Journal of the Korean Institute of Gas
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• v.3 no.2 s.7
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• pp.62-69
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• 1999

This paper presents a design method of dynamic positioning control system(DPS) for floating Platform with rotatable and retractable thrusters using H$\infty$ servo control design method. The norm band of uncertainty is captured by multiplicative perturbation between nominal model and reduced order model. A controller robust to the uncertainty is designed applying H$\infty$ synthesis. The control law satisfying robust stability and nominal performance condition is determined through the mixed sensitivity approach. The control algorithm was evaluated on the basis of computer simulation for a proposed DPS design method and experiments was carried out with an image processing method for measurement of DPS position in a water tank The results of overall experiments show that proposed control method will be good to keep at a specified position. And they are compared with the experimental results by LQG synthesis and H$\infty$ optimal control design method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.3
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• pp.133-138
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• 2022

Digital radiation inspection equipment is a medical device that deals with human life and requires stability and high reliability. However, this system is currently the most advanced technology and the domestic market is almost occupied by European products including Japan. Therefore, research and development are needed not only to replace domestic medical devices, which are largely dependent on expensive imported products, but also to develop more economical and user-oriented products that are easy to operate and produce devices that lead to accurate diagnosis. In particular, among the digital X-ray systems, the motor driving technology and the mechatronics technology related to the development of mechanical devices have matured to some extent in Korea. In this paper, selection of AC servomotor for digital radiation inspection suitable for imaging purpose, and application of conversion device and control method to check performance and improve problems.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.11
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• pp.1022-1032
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• 2000

We propose a sliding mode controller tracking the states of a time-varying reference model. The reference model generates the desired trajectories of the states, and the sliding mode controller regulates robustly the errors between the desired states and the measured states. We apply this controller to the overhead crane. Its reference model generates the trajectories of the damped-out swing angle and the swing angular velocity to suppress the swinging motion caused by the acceleration and the deceleration of crane transportation. Also, this model generates the desired trajectories of the position and velocity of the crane. The crane model is identified from the experimental data using an orthogonal function. Kalman filtering is applied to estimate the crane states. The designed controller is simulated on a computer and is tested through a 2-ton industrial overhead crane using the vector-controlled servo motor system. It is verified that, from the simulated and experimental results, the sliding mode controller tracking a time-varying reference model works well.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.3
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• pp.33-38
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• 2011

A cubic spline trajectory planner with arc-length parameter is formulated with estimation by summing up to the 3rd order in Taylor's expansion. The PVAJT motion planning is presented to reduce trajectory calculation time at every cycle time of servo control loop so that it is able to generate cubic spline trajectory in real time. This method can be used to more complex spline trajectory. Several case studies are executed with different values of cycle time and sampling time, and showed the advantages of the PVAJT motion planner. A DSP-based motion controller is designed to implement the PVAJT motion planning.

• Transactions of Materials Processing
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• v.14 no.9 s.81
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• pp.764-771
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• 2005

This study is related with the development of CNC spinning machine and the axisymmetric conventional spinning such as drum type and conical type steel shells. The CNC spinning machine is constructed with heavy duty frame and the hydraulic servo system is applied in order to give the exactness of motion control. The experiment has been carried out considering feeding velocity, mandrel shape, and the corner radius of mandrel and forming rollers. As a result of experiment, the limiting spinning ratio and thickness strain distribution are obtained and it can be seen that the spinnability is dominant to the feeding velocity and corner radius of forming roller. This research can contribute to the development of axisymmetric mechanical part which is applicable to automotive and aerospace industry.

• Current Optics and Photonics
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• v.5 no.3
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• pp.289-297
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• 2021

We describe a comb-mode resolving spectroscopic technique by direct time-domain phase correction of unstable interferograms obtained from loosely locked two femtosecond lasers. A low-cost continuous wave laser and conventional repetition rate stabilization method were exploited for locking carrier and envelope phase of interferograms, respectively. We intentionally set the servo control at low bandwidth, resulting in severe interferograms' fluctuation to demonstrate the capability of the proposed correction method. The envelope phase of each interferogram was estimated by a quadratic fit of carrier peaks to correct timing fluctuation of interferograms in the time domain. After envelope phase correction on individual interferograms, we successfully demonstrated 1 Hz linewidth of RF comb-mode over 200 GHz optical spectral-bandwidth with 10-times signal-to-noise ratio (SNR) enhancement compared to the spectrum without correction. Besides, the group delay difference between two femtosecond pulses is successfully estimated through a linear slope of phase information.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.1133-1134
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• 2023

FASTECH 사(社)의 Ezi-Servo Plus-E 제품군은 Windows 기반의 모션 라이브러리와 GUI 프로그램을 이용하여 모션 컨트롤을 수행한다. 이를 Linux기반의 GUI 프로그램과 모션 라이브러리를 작성하여 Raspberry Pi 환경에 적용하였다. Windows와 Linux 기반의 두 프로그램으로 각각 모터를 구동시키고 모터의 위치값을 비교하여 150 미만의 작은 차이를 확인하였다. 이 연구를 통해 Linux 임베디드 시스템으로 모션 컨트롤 시스템을 구축하려는 잠재 고객의 수요를 맞출 수 있을 것으로 기대한다.