• Journal of Korea Society of Industrial Information Systems
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• v.4 no.1
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• pp.58-62
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• 1999

This paper shows that is possible to identify the system's input-output dynamics exactly in the presence of unknown periodic disturbances for the Active Engine Mount Control Application .The disturbance frequencies and waveforms can be completely unknown and arbitrary. Only measurements of a control excitation signal and the disturbance-contaminated response are used for identification. Examples are given to illustrate the method, including the identification and vibration control of active engine mount for automobile.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1578-1586
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• 2016

A power quality improvement scheme for grid connected inverters, even in the presence of the disturbances in grid voltages due to harmonic distortions and three-phase imbalance, is presented for distributed generation (DG) power systems. The control objective is to force the inverter currents to follow their references with robustness even under external disturbances in grid voltages. The proposed scheme is realized by a disturbance observer (DOB) based current control scheme. Since the uncertainty in a system can be effectively canceled out using an estimated disturbance by the DOB, the resultant system behaves like a closed-loop system consisting of a disturbance-free nominal model. For experimental verification, a 2 kVA laboratory prototype of a grid connected inverter has been built using a digital signal processor (DSP) TMS320F28335. Through comparative simulations and experimental results under grid disturbances such as harmonic distortion and imbalance, the effectiveness of the proposed DOB based current control scheme is demonstrated.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.5
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• pp.129-140
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• 2014

BIST(Built-in self test) is to detect various faults of the existing memory and BIRA(Built-in redundancy analysis) is to repair detected faults by allotting spare. Also, BISR(Built-in self repair) which integrates BIST with BIRA, can enhance the whole memory's yield. However, the previous methods were suggested for RAM and are difficult to diagnose disturbance that is NAND-type flash memory's intrinsic fault when used for the NAND-type flash memory with different characteristics from RAM's memory structure. Therefore, this paper suggests a BISD(Built-in self diagnosis) to detect disturbance occurring in the NAND-type flash memory and to diagnose the location of fault, and BISR to repair faulty blocks.

• Journal of Drive and Control
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• v.14 no.2
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• pp.9-15
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• 2017

The steering systems of all-terrain cranes have been developed with various control strategies for the stability and drivability. To optimally control the input steering angle, an accurate mathematical model that represents the actual crane dynamics is required. The derivation of an accurate mathematical model to optimally control the steering angle, however, is difficult since the steering-control strategy generally varies with the magnitude of the crane's longitudinal velocity, and the postures of the crane's working parts vary while it is being driven. To address this problem, this paper proposes an automatic steering-control algorithm that is based on the MPC (model predictive control) with a disturbance observer for all-terrain cranes. The designed disturbance observer of this study was used to estimate the error between the base steering model and the actual crane. A model predictive controller was used for the computation of the optimal steering angle, along with the use of the base steering model with an estimated uncertainty. Performance evaluations of the designed control algorithms were conducted based on a curved-path scenario in the Matlab/Simulink environment. The performance-evaluation results show a sound reference-path-tracking performance despite the large uncertainties.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.5
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• pp.352-360
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• 2010

This paper proposes a precise position control of an automatic door using a disturbance observer. Although the conventional PID controller is usually used for an automatic door system, the demand of the robust controller considering the parameter deviations and disturbances is increasing due to the various size and weight of a door. The linear model for an automatic door system is presented. Based on this model, the LQR controller using a state feedback controller and an observer are suggested. A disturbance observer to compensate the undesirable factors is also proposed. Simulation and Experimental results are presented to illustrate the feasibility of the proposed control strategy.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.5
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• pp.401-410
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• 2010

This paper proposes an automatic door system which improves the safety of conventional automatic door systems by complementing the external safety sensors. Disturbance observer using the model of automatic door system and neural network is designed. The proposed algorithm compares the observed disturbance with the output of neural network. Experimental results are presented to illustrate the feasibility of the proposed control strategy. The proposed strategy is expected to improve the safety of an automatic door system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.8
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• pp.996-1003
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• 1999

This paper propose a position-speed controller with an estimator which can estimate states and disturbance. The overall control system consists of two parts: the position-speed controller and an estimator. The Kalman filter applied as state-feedback controller is an optimal state estimator applied to a dynamic system that involves random perturbations and gives a linear, unbiased and minimum error variance recursive algorithm to optimally estimate the unknown state. Therefore, we consider the error problem about the servo system modeling and the measurement noise as a stochastic system and implement a optimal state observer, and enhance the estimate performance of position and speed using that. Using two-degree-of freedom(TDOF) conception, we design the command input response and the closed loop characteristics independently. The servo system is to improve the closed loop characteristics without affecting the command imput response. The characteristics of the closed loop system is improved by suppressing disturbance torque effectively with the disturbance observer using a inverse-transfer matrix. Therefore, the performance of overall position-speed controller is enhanced. Finally, the performance of the proposed controller is exemplified by some simulations and by applying the real servo system.

• Journal of Ecology and Environment
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• v.41 no.6
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• pp.152-164
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• 2017

Background: Natural regeneration of seedlings as well as saplings of Korean fir has been significantly impacted by the browsing from the early stages of their development, potentially, by roe deer for the last two to three decades at the study site since late 1980s. This study was carried out to investigate current status of the disturbance in the seedling development of Korean fir (Abies koreana) on Mt. Hallasan, Jeju Island, Korea. Methods: Field survey was carried out during June and August in 2016 to measure the characteristics of study site and understory vegetation by applying systematic sampling to 125 plots of $5m{\times}5m$ quadrat located on eastern slope of the mountain. Correlation and regression analyses were applied to the variables quantified from the data sets using the SAS software. Results: No saplings with their diameters at breast heights smaller than 5.0 cm were found at the study site indicating the serious disturbance in the natural regeneration of Korean fir at the study site. No seedlings with their heights taller than 36.0 cm were found at the study site indicating even more serious disturbance during earlier stage of the natural regeneration of Korean fir at the study site. A total of 616 individuals of the seedlings of Korean fir were found at 54 out of 125 sampling plots. One hundred thirty-eight seedlings (22.4%) out of 616 individual seedlings have the vestiges for being grazed, potentially, by roe deer. Conclusions: Due considerations should be given to the effects of browsing of the seedlings by roe deer to promote the natural regeneration of Korean fir, ultimately to restore Korean fir. It is needed for the managers of the forest to install fences around the forest area. Exclosure experiments as well as enclosure experiments of different densities of browsing should be carried out. In addition, treatment with different densities of Jeju dwarf bamboo should also be included in the experiment on Mt. Hallasan National Park, Jeju Island, Korea.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.95.1-95
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• 2001

This paper is concerned with a novel S-stability (stochastic-stability) concept in linear time-invariant stochastic systems, where a stochastic mode in dynamics depends on both the external disturbance and the inner-parameter variations. This leads to an EAG (eigenstructure assignment gaussian) problem; that is, the problem of associating S-eigenvalues (stochastic-eigenvalues), S-eigenvectors (stochastic-eigenvectors), and their PDFs (probability density functions) with the stochastic information of the systems with the required stochastic specifications. These results explicitly characterize how S-eigenvalues, S-eigenvectors and their PDFs in the complex plane may impose S-stability on stochastic systems.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.219-222
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• 1995

This paper presents a control law of multiple actuation servo systems. Multiple actuation systems have an ability to solve some difficult engineering problems; Coulomb friction, backlash, and disturbance. This fact is shown by basic experiments as well as theoretical analysis. The proposed control strategy remarkably improves the performance comparing with conventional single actuation systems.