• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.8
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• pp.757-764
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• 1991

This paper proposes a novel control method of voltage type current-controlled reactive/harmonic compensator. The proposed method does not rely on the explicit computation of load power, but indirectly controls the compensation current by regulating dc link voltage of the converter. It is shown that the system can be modeled as a simple linear system that facilitates an analytical approach to the system characteristics. With the model, the effects of the controller gains on the dynamic and steady state response of the system are investigated. Experimental results show that the proposed control method works well in spite of the simplicity of control circuitry.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.597-599
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• 2006

In this paper, we propose an artificial intelligence method to compensate the nonlinearity error which occurs in the heterodyne laser interferometer. Some superior properties such as long measurement range, ultra-precise resolution and various system set-up lead the laser interferometer to be a practical displacement measurement apparatus in various industry and research area. In ultra-precise measurement such as nanometer or subnanometer scale, however, the accuracy is limited by the nonlinearity error caused by the optical parts. The feedforward neural network trained by back-propagation with a capacitive sensor as a reference signal minimizes the nonlinearity error and we demonstrate the effectiveness of our proppsed algorithm through some experimental results.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.136-138
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• 2006

Recently, network systems are widely used in several areas, and some considerable attentions have been directed to the Networked Control System(NCS). In NCS, network-induced delays are inevitable, and they sometimes degrade the performance of networked control systems to be a source of potential instability. In this paper, We proposes a compensation method for networked control system subject to network-induced delays by using a simple method, which is based on a sort of predictive strategy. To evaluate its feasibility and effectiveness, a real-time NCS for a rotary inverted pendulum is implemented via an Ethernet. Based on the experimental results. we show that the proposed simple method can be a practical and feasible solution to NCS design.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2007.06a
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• pp.11-14
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• 2007

An additive servo-system is developed to improve straightness of linear motor stages. For linear motor stages used in the field of high-precision linear motion process, high straightness accuracy is necessary as well as positioning accuracy in the longitudinal axis. In such cases, machining and assembling cost increases to improve the straightness accuracy. An electro-magnetic actuator which is relatively cost effective than any other conventional servo-systems is suggested to compensate the fixed straightness error. To overcome the compensation error due to modeling error and friction disturbance, a sliding mode control is addressed. The effectiveness of the suggested mechanism and the control are illustrated along with some experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.268-272
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• 1996

Error correction effect for maladjusted stereo cameras with calibrated pixel distance parameter is presented. The camera calibration is a necessary procedure for stereo vision-based depth computation. Intra and extra parameters should be obtain to determine the relation between image and world coordination through experiment. One difficulty is in camera alignment for parallel installation: placing two CCD arrays in a plane. No effective methods for such alignment have been presented before. Some amount of depth error caused from such non-parallel installation of cameras is inevitable. If the pixel distance parameter which is one of intra parameter is calibrated with known points, such error can be compensated in some amount. Such error compensation effect with the calibrated pixel distance parameter is demonstrated with some experimental results.

• International Journal of Control, Automation, and Systems
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• v.4 no.1
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• pp.113-123
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• 2006

In this paper, an improved direct torque control (DTC) method for sensorless matrix converter drives is proposed which enables to minimize torque ripple, to obtain unity input power factor, and to achieve good sensorless speed-control performance in the low speed operation, while maintaining constant switching frequency and fast torque dynamics. It is possible to combine the advantages of matrix converters with the advantages of the DTC strategy using space vector modulation and a flux deadbeat controller. To overcome the phase current distortion by the non-linearity of a matrix converter drive, the simple non-linearity compensation method using PQR power theory are presented in the proposed scheme. Experimental results are shown to illustrate the feasibility of the proposed strategy.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.4
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• pp.246-250
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• 2014

Large mutual capacitance touch screen panels (TSP) are susceptible to display and ambient noise. This paper presents a multi-touch detection algorithm using an efficient noise compensation technique for large mutual capacitance TSPs. The sources of noise are presented and analyzed. The algorithm includes the steps to overcome each source of noise. The algorithm begins with a calibration technique to overcome the TSP mutual capacitance variation. The algorithm also overcomes the shadow effect of a hand close to TSP and mutual capacitance variation by dynamic threshold calculations. Time and space filters are also used to filter out ambient noise. The experimental results were used to determine the system parameters to achieve the best performance.

• Journal of Industrial Technology
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• v.22 no.B
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• pp.133-139
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• 2002

In precision instrumentation system, an A/D conversion of signal conditioning has been always suffered from some problems ; offset and drift voltage with environmental situation. This paper suggests a method of reducing the offset voltage and the drift error from the A/D conversion hardware using analog signal switching technique with specific operational amplifier circuits. Also, we have designed a hardware active filter and a software digital filter with Auto Zero Tracking algorithm for better dignal process of the our proposed weighing system. Software technique was performed to obtain the stable data from A/D converter. As a result of our experimental works, the proposed system is expected to be used in the industrial field where a high precision measurement is required.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.155-160
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• 2000

In this paper, we investigated quality properties for the expansive of the CaO-$CaSO_4$ family which used to compensate dry-shrinkage in the floor mortar of On-Dol heating System. This experimental study established the mix condition with quantity of the expansive and is to investigate the relativity between the compress strength and the length change and the relativity between the chemical properties and the length change with the analysis of the physical and chemical properties. As a result of the study, the expansive is controlled by more the CaO than the $CaSO_4$. The relativity between the compress strength and the length change is expressed by exponential function, showing that if the expansive performance is increased, the compress strength is decreased. And the relativity between the chemical properties and the length change is only relative the quantity of the F-CaO among the chemical properties, is expressed by the second order function, showing that if the F-CaO is increased, the expansive performance is increased.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.505-508
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• 1999

Conventional adaptive speed estimators cannot avoid the influence of the non-linear inductance variation under the saturation conditions. Without speed sensors, it is difficult to identify the inductance variation using a reactive power mode because the model contains a term of the rotor speed. In this paper, we propose a novel speed estimator having hybrid architecture in order to estimate both the rotor speed and the inductance variation simultaneously when the motor flux is saturated. Proposed estimator consists of the error between the flux obtained from the stator voltage equation and the flux estimated from the rotor flux observer. Introducing a new correction term into the estimator increases the estimation ability of the conventional speed estimator even though the motor flux is saturated. The convergence of the speed estimation error is examined by simulation Furthermore, the experimental results show the validity of the proposed method.