• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.133-135
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• 2006

This paper considers a speed control problem of DC motor under load variations. In order to reduce the effect of load variation, a disturbance observer has been designed for the given system. With a cheap encoder there exists considerable measurement noise in the velocity feedback and it should be reflected in designing the disturbance observer. The authors have obtained the nominal transfer function of a DC motor and designed a disturbance observer for the control purpose. With the disturbance observer a digital controller has been implemented using a DSP(TMS320F2812). Some experiments show the enhanced performance of the control system with the proposed method.

• Nuclear Engineering and Technology
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• v.4 no.3
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• pp.181-185
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• 1972

A digital bandpass filter method is investigated for the data treatment in tile measurement of the reactor transfer function. It was found that the technique is very effective in eliminating the effects of external noise. A computer code was programmed for this method. The frequency response of a digital filter is calculated, and the data treatment with this method using a digital computer was illustrated for triangular and square waveforms. Error and restriction involved in use of this method are discussed.

• Journal of Korean Vacuum Science & Technology
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• v.3 no.2
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• pp.107-111
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• 1999

We developed the experimental function (ERF) which can be used for the numerical curve fitting analysis in photoelectron spectroscopy (PES). We selected the core-levels of Ag 3d5/2 and Au 4f7/2 to obtain the ERF from the measured core-level spectra. For the numerical fourier transformation we applied the fast transform (FFT) algorithm. we considered optical (Wiener) filtering with the FFT due to noise and used Hann window function to remedy the information leakage in frequency domain due to discrete and finite sampling of measurement. The comparison of the curve fitting results using the ERF obtained in this work and the mathematical response function with a gaussian in the conventional approach shows clearly the improvement of the curve fitting analysis.

• Journal of Positioning, Navigation, and Timing
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• v.6 no.4
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• pp.205-210
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• 2017

Multi-Global Navigation Satellite System (GNSS) can significantly improve the positioning accuracy and convergence speed. The reliability and availability of multi-GNSS precise point positioning (PPP) is steadily increasing with the rapid development of GNSS satellites. In this study, multi-GNSS PPP analysis is performed to compare the positioning precision by processing the observations from different GNSS systems (GPS, GLONASS, Galileo and BeiDou). To improve the positioning performance of the multi-GNSS PPP, we employed the weighed measurement noise (WMN) method. After applying WMN method to multi-GNSS PPP, positioning precision is improved by approximately 26.3% compared to the GPS only solutions, and by approximately 9.1% compared to combined GPS, GLONASS, and Galileo PPP.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.1
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• pp.67-76
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• 2005

In this paper, An analysis on the intelligence system for a biped walking robot(BWR) was made and its results were applied to the BWR. Various sensors were applied to the developed BWR for autonomous and intelligent walk in unknown environments. To measure the distance between the object and BWR, ultrasonic sensor and infrared-rays sensor were used. To identity surrounding environments, vision system was used. Gyro sensor was used to control the posture of BWR. Also, piezoelectricity sensor was used to identity the pressure of foot landing on the surface. Sensors applied to the robot have measurement errors according to noises or walking environments. To improve the function of these sensors, influences of noise or sensing errors were minimized using a sensor fusion scheme. A gait test using the sensor fusion system was performed, and its results are presented.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.8
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• pp.792-799
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• 2008

Motion estimation is crucial in a remote control for its convenience or accuracy. Time delays, however, can occur in the problem because data communication is required through a network. In this paper, state estimation problem with uncertain time delayed measurements is addressed. In dynamic system with noise, after taking measurements, it often requires some time until that is available in the filter algorithm. Standard filters not considering this time delays cannot be used since the current measurement is related with a past state. These delayed measurements are solved with augmented extended Kalman filter, and the uncertainty of delayed time is also resolved based on an explicit formulation. The proposed method is analyzed and verified by simulations.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.5
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• pp.615-623
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• 2016

The paper describes a hysteretic buck converter including a differentiator and an adaptive hysteresis window controller. Differentiating the feedback signal achieves ultra-fast switching of the buck converter. The adaptive hysteresis window control allows a monotonous operation with predictable noise spectrum, and gives way to efficient design for variable supply and output voltages. The measurement results in a $0.13-{\mu}m$ CMOS process indicated that the switching frequency became double times higher, and the voltage ripple was reduced by up to 69%. They also indicated that the normalized switching frequency variation was reduced by 74% with variable $V_{DD}$ and by 63% with variable $V_{OUT}$. The power efficiency was improved by 3.5% depending on loading condition.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.505-510
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• 2008

FBG Sensor, which is smaller than strain gauge and has better durability and does not have a noise from electromagnetic waves, was adapted to develope a smart anchor. A series of pullout tests were performed to verify the feasibility of smart anchor and find out the load transfer mechanism around the steel wire fixed to rock with grout. Distribution of shear stresses at steel wire-grout interface is assessed from the measured strain distribution by the optical fiber sensors and compared with stress distributions predicted by Farmer's and Aydan's formulas. It was found that present theoretical formulas may underestimate the failure depth and magnitude of shear stresses when the pullout loads increase.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.9 no.2
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• pp.85-93
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• 1984

This paper, with the linear multivariable systems as a model, proposes a method of evaluating the Kalman gain of the state estimator according to the shifting of poles in the system. The stochasic probability of the process and measurement noise is assumed to be identical to the stationary process. The proposed method, based on the diagonalized system, is easy to implement computationally if the correspondence between the poles of the estimator and the response of the system can be determined. Finally several examples are given to confirm and illustrate proposed method derived here.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.655-658
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• 2003

The crack of concrete structure plays an important role in the durability and safety of structure. Therefore, the features such as width, length, and direction of that must be measured periodically. The conventional method of measurement of cracks is manually sketched, however. it takes a fairly long time and lacks quantitative objectivity. This study proposes the algorithm to extract and analyze cracks automatically. The proposed algorithm is composed of two sub-algorithms. The extraction algorithm includes elimination of effect due to light, binarization. and noise reduction. The analysis algorithm includes thinning process, labeling, and calculation of crack width, length, and direction. The test to demonstrate the algorithm is fulfilled using the images of cracks on real concrete surface.