• International Journal of Control, Automation, and Systems
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• v.6 no.2
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• pp.269-277
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• 2008

This paper proposes a necessary and sufficient condition of convergence in the $L_2$-norm sense for a feedback-based iterative learning control (ILC) system including a multi-input multi-output (MIMO) linear time-invariant (LTI) plant. It is shown that the convergence conditions for a nominal plant and an uncertain plant are equal to the nominal performance condition and the robust performance condition in the feedback control theory, respectively. Moreover, no additional effort is required to design an iterative learning controller because the performance weighting matrix is used as an iterative learning controller. By proving that the least upper bound of the $L_2$-norm of the remaining tracking error is less than that of the initial tracking error, this paper shows that the iterative learning controller combined with the feedback controller is more effective to reduce the tracking error than only the feedback controller. The validity of the proposed method is verified through computer simulations.

• Earthquakes and Structures
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• v.24 no.4
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• pp.247-258
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• 2023

Multiple pounding tuned rolling mass damper (MPTRMD) distributed in the cavity of voided slabs is proposed to passively control multi-story frame structures, which disperses the mass of the oscillator to multiple dampers so that the control device can be miniaturized without affecting the vibration control performance. The mechanism and the differential motion equations of the MPTRMD-controlled multi-degree-of-freedom system are derived based on the Lagrange principle. Afterward, this advanced RMD is applied to a simplified 20-floor steel frame to evaluate the seismic control performance in the numerical analysis. A four-storey frame structure equipped with MPTRMD is then taken for a shaking table test to verify its effectiveness of control performance. The pounding mechanism has been detailed studied numerically and experimentally as well. The numerical and experimental results show that the proposed damper is practically promising not only for its prominent control performance but also for its lightweight and space-saving. Additionally, the pounding mechanism influenced by the variable impact parameters exhibits a balance between the two effects of motional limitations and energy dissipation.

• Journal of Korea Society of Industrial Information Systems
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• v.10 no.2
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• pp.21-25
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• 2005

Human performance of system control under excessive mental-workload may differ from stable situation. In this study, design guidelines of secondary control system were introduced to enhance performance of safety control system. Under urgent situation, the first performance criterion is not a reaction time but safe control reaction that prevents system disaster. Therefore it is important to find out the facts that are mainly related system safety. Experimental results show performance of primary task didn't reflect whole system influence within a limited short reaction time. In this situation, the secondary task is more sensitive to system influence that varied with some factors of urgent status. Therefore, when a system proceeds to abnormal and unsafe status, and even more the reaction time is limited within a very short time to control the system, the estimation of human performance is more sensitive using secondary task performance then primary task performance. Those results mean it is required to develop various secondary tasks to design safety control systems preventing disaster, And also require many studies of estimation methods human performances especially when system status varies dangerous and/or unsafe situation.

• Journal of Korean society of Dental Hygiene
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• v.21 no.5
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• pp.675-683
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• 2021

Objectives: This study aimed to verify the relations of COVID-19 infection-related knowledge, dental infection control performance, and psychosocial health of dental hygienists. Methods: From the data was analyzed through the frequency analysis, t-test, one way ANOVA, and pearson's correlation analysis with a total of 198 dental hygienists using SPSS Statistics 21.0. Results: The correct answer rate for knowledge about COVID-19 was higher with a bachelor's degree or higher. Thus, when the level of education was higher, the performance was also high (p<0.01). COVID-19 infection control performance was highly shown in case of high age (4.43) (p<0.05) and the married (4.42) (p<0.01). Infection control performance was high when they had an educational experience of COVID-19 infection control (4.46), and when the infection control guidebooks were equipped in their workplaces (p<0.001). Degree of psychosocial health of research subjects was shown in the order of potential stress (60.6%), high-risk stress (23.7%), and healthy (15.7%). Infection control performance was higher, the psychosocial health was healthy. Conclusions: For the response to COVID-19 infectious disease and the preparation for mutated viruses and new infectious diseases in the future, it would be necessary to establish the concrete measures for establishing the strict infection control system for dental clinics and also enhancing the psychosocial health of dental hygienists.

• Smart Structures and Systems
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• v.19 no.5
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• pp.487-497
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• 2017

Semi-active devices use the building's own motion to produce resistive forces and are thus strictly dissipative and require little power. Devices that independently control the binary open/closed valve state can enable novel device hysteresis loops that were not previously possible. However, some device hysteresis loops cannot be obtained without active analog valve control allowing slower, controlled release of stored energy, and is presents an ongoing limitation in obtaining the full range of possibilities offered by these devices. This in silico study develops a proportional-derivative feedback control law using a validated nonlinear device model to track an ideal diamond-shaped force-displacement response profile using active analog valve control. It is validated by comparison to the ideal shape for both sinusoidal and random seismic input motions. Structural application specific spectral analysis compares the performance for the non-linear, actively controlled case to those obtained with an ideal, linear model to validate that the potential performance will be retained when considering realistic nonlinear behaviour and the designed valve control approach. Results show tracking of the device force-displacement loop to within 3-5% of the desired ideal curve. Valve delay, rather than control law design, is the primary limiting factor, and analysis indicates a ratio of valve delay to structural period must be 1/10 or smaller to ensure adequate tracking, relating valve performance to structural period and overall device performance under control. Overall, the results show that active analog feedback control of energy release in these devices can significantly increase the range of resetable, valve-controlled semi-active device performance and hysteresis loops, in turn increasing their performance envelop and application space.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2612-2616
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• 2003

Method for performance monitoring and diagnosis of a MIMO control system has been studied aiming at application to model predictive control (MPC) for industrial processes. The performance monitoring part is designed on the basis of the traditional SPC/SQC method. To meet the underlying premise of Schwart chart observation that the observed variable should be univariate and independent, the process variables are decorrelated temporally as well as spatially before monitoring. The diagnosis part was designed to identify the root of performance degradation among the controller, process, and disturbance. For this, a method to estimate the model-error and disturbance signal has been devised. The proposed methods were evaluated through numerical examples.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.9
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• pp.569-575
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• 2004

This paper is proposed adaptive fuzzy-neural network(FNN) controller for high performance of induction motor drive. The design of this algorithm based on FNN controller that is implemented using fuzzy control and neural network. This controller uses fuzzy rule as training patterns of a neural network. Also, this controller uses the back-propagation method to adjust the weights between the neurons of neural network in order to minimize the error between the command output and actual output. A model reference adaptive scheme is proposed in which the adaptation mechanism is executed by fuzzy logic based on the error and change of error measured between the motor speed and output of a reference model. The control Performance of the adaptive FNN controller is evaluated by analysis for various operating conditions. The results of analysis prove that the proposed control system has strong high performance and robustness to parameter variation. and steady- state accuracy and transient response.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.108-112
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• 2003

A feedforward amplifier, which is composed of several components, is an open loop system. Therefore, feedforward amplifiers are apt to deteriorate the performance according to the environmental changes even though the cancellation performance and the linearization bandwidth of feedforward systems are superior to other linearization methods. A control method is needed for maintaining the original performance of feedforward amplifiers or to keep the performance within a little error bounds. In this paper, an adaptive control method, which has a good convergence characteristic and is easy to implement, is suggested. The characteristics of the suggested control method compare with the characteristics of other control methods and the simulation results are presented.

• Journal of Power System Engineering
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• v.14 no.5
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• pp.56-62
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• 2010

In this paper, a recurrent cerebellar modulation articulation control (RCMAC) has been developed for improvement of noise attenuation performance in active noise control system. For the narrow band noise, a filter-x least mean square (FXLMS) method has bee frequently employed as an algorithm for active noise control (ANC) and has a partial satisfactory noise attenuation performance. However, noise attenuation performance of an ANC system with FXLMS method is poor for broad band noise and nonlinear path since it has linear filtering structure. Thus, an ANC system using RCMAC is proposed to improve this problem. Some simulations in duct system using harmonic motor noise and KTX cabin noise as a noise source were executed. It is shown that satisfactory noise attenuation performance can be obtained.

• Korean Management Science Review
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• v.31 no.3
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• pp.77-94
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• 2014

This study empirically investigated the relationships among inter-organizational cost management (IOCM), cooperation with suppliers, information exchange between partners, inter-organizational learning, control integration, and the supply-chain performance of a firm. The results showed that the adoption of IOCM positively affects the collaboration between buyers and suppliers, which also leads to the increased information flow between them. According to the results of this study, it was found that inter-organizational information flow causes inter-organizational learning, and this learning contributes to the improved supply-chain performance. In this study, the positive effects of the cooperation with suppliers through IOCM on the control integration in supply-chains were not empirically confirmed. However, the impact of IOCM on control integration was significant and positive. Finally, the fact that the enhanced control integration can improve the supply-chain performance of a firm was empirically demonstrated.