• Title/Summary/Keyword: Control Performance

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Experimental and Computational Study on Separation Control Performance of Synthetic Jets with Circular Exit

  • Kim, Minhee;Lee, Byunghyun;Lee, Junhee;Kim, Chongam
    • International Journal of Aeronautical and Space Sciences
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    • v.17 no.3
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    • pp.296-314
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    • 2016
  • This paper presents experimental and computational investigations of synthetic jets with a circular exit for improving flow control performance. First, the flow feature and vortex structure of a multiple serial circular exit were numerically analyzed from the view point of flow control effect under a cross flow condition. In order to improve separation control performance, experimental and numerical studies were conducted according to several key parameters, such as hole diameter, hole gap, the number of hole, jet array, and phase difference. Experiments were carried out in a quiescent condition and a forced separated flow condition using piezoelectrically driven synthetic jets. Jet characteristics were compared by measuring velocity profiles and pressure distributions. The interaction of synthetic jets with a freestream was examined by analyzing vortical structure characteristics. For separation control performance, separated flow over an airfoil at high angles of attack was employed and the flow control performance of the proposed synthetic jet was verified by measuring aerodynamic coefficient. The circular exit with a suitable hole parameter provides stable and persistent jet vortices that do beneficially affect separation control. This demonstrates the flow control performance of circular exit array could be remarkably improved by applying a set of suitable hole parameters.

Factors Influencing the Infection Control Performance of Catheter-Associated Urinary Tract Infection of Nurses in Hospitals (중소병원 간호사의 유치도뇨관 관련 요로감염 감염관리 수행 영향 요인)

  • Choi, Eun Yeong;Song, Min Sun
    • Journal of Korean Clinical Nursing Research
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    • v.25 no.3
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    • pp.303-313
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    • 2019
  • Purpose: The purpose of this study was to examine nurses' knowledge, health beliefs, and performance regarding the infection control of catheter-associated urinary tract infection (CAUTI) and to identify factors affecting their infection control performance of the CAUTI. Methods: The subjects were 166 nurses at three hospitals with less than 300 beds in urban areas.Data were collected using structured questionnaires about knowledge, health beliefs, and performance regarding the infection control of the CAUTI. Statistical analysis included t-test, ANOVA, Pearson's Correlation Coefficients, Multiple regression analysis. Results: The factors affecting the infection control performance of CAUTI were knowledge (β=.18, p=.010), perceived seriousness (β=.25, p=.001), perceived barriers (β=.41, p<.001), and cues to action (β=.15, p=.030), and these factors explained 28.7% of the variance for the infection control performance of the CAUTI. Conclusion: In this study, higher levels of knowledge, perceived seriousness and, cues to action, and lower perceived barriers resulted in a corresponding higher performance in the infection control of CAUTI. Based on these findings, providing intervention programs enhancing the health beliefs of nurses is necessary to ensure their infection control performance of the CAUTI.

Improving Current Control Performance by Parameter Estimation of PWM Converter (PWM 컨버터의 상수추정을 통한 전류제어 성능 개선)

  • 이진우
    • Proceedings of the KIPE Conference
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    • 2000.07a
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    • pp.286-289
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    • 2000
  • from the viewpoint of model-based current control it is indispensable to use the accurate system parameters for the high control performance. This paper adopts the Least-Squares algorithm as a parameter estimation scheme because it has the fast convergence rate and the low sensitivity to noises. in case of the PI current controller with high gains the simulation results show that the adopted estimation scheme can be successfully applied to PWM converters and also show that the control performance can be improved by using the estimated parameters.

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Model-based Predictive Control Approach to Continuous Process based on Iterative Learning Concept

  • Chin, In-Sik;Cho, Moon-Ki;Lee, Jay-H;Lee, Kwang-Soon
    • 제어로봇시스템학회:학술대회논문집
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    • 2001.10a
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    • pp.41.1-41
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    • 2001
  • Since the advanced control technique such as model predictive control has been introduced to industrial plant, there have been many progresses in the process control. As a way to improve the control performance, the on-line process optimizer was integrated with the advance controller. In this study, a control technique which improves the control. As the number of changes by the optimizer is increased, the control performance of the proposed algorithm is improved. Its control performance is shown via an numerical example.

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Improvement of Maneuvering Feeling of Human-Mechanical Cooperative System and Its Application to Electric Power Steering System

  • Mukai, Yasuhiko;Ukai, Hiroyuki;Iwasaki, Makoto;Matsui, Nobuyuki;Hayashi, Jiro;Makino, Nobuhiko;Ishikawa, Hiroshi
    • 제어로봇시스템학회:학술대회논문집
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    • 2003.10a
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    • pp.728-733
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    • 2003
  • In human-mechanical cooperative systems, a significant issue is to improve the control performance and the maneuvering feeling of human operation. However, since it is not easy to evaluate the feeling of operators numerically, control engineers design controllers only through experience. Thus, in this paper, a new evaluation method for control performance of human-mechanical cooperative system is proposed based on the reserge waveform. Various distortions of waveform represent deteriorations of control performance and maneuvering feeling. In some cases, since there is a tradeoff between the control performance and the maneuvering feeling, it is difficult to compensate for both of them by usual feedback controllers. To overcome this situation, the two degrees of freedom control system is applied to human-mechanical cooperative system. Some numerical simulation results for an electric power steering system are shown to confirm the effectiveness of proposed control design method.

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Improvement of Control Performance by Data Fusion of Sensors

  • Na, Seung-You;Shin, Dae-Jung
    • International Journal of Fuzzy Logic and Intelligent Systems
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    • v.4 no.1
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    • pp.63-69
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    • 2004
  • In this paper, we propose a general framework for sensor data fusion applied to control systems. Since many kinds of disturbances are introduced to a control system, it is necessary to rely on multisensor data fusion to improve control performance in spite of the disturbances. Multisensor data fusion for a control system is considered a sequence of making decisions for a combination of sensor data to make a proper control input in uncertain conditions of disturbance effects on sensors. The proposed method is applied to a typical control system of a flexible link system in which reduction of oscillation is obtained using a photo sensor at the tip of the link. But the control performance depends heavily on the environmental light conditions. To overcome the light disturbance difficulties, an accelerometer is used in addition to the existing photo sensor. Improvement of control performance is possible by utilizing multisensor data fusion for various output responses to show the feasibility of the proposed method in this paper.

Geometric charts with bootstrap-based control limits using the Bayes estimator

  • Kim, Minji;Lee, Jaeheon
    • Communications for Statistical Applications and Methods
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    • v.27 no.1
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    • pp.65-77
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    • 2020
  • Geometric charts are effective in monitoring the fraction nonconforming in high-quality processes. The in-control fraction nonconforming is unknown in most actual processes; therefore, it should be estimated using the Phase I sample. However, if the Phase I sample size is small the practitioner may not achieve the desired in-control performance because estimation errors can occur when the parameters are estimated. Therefore, in this paper, we adjust the control limits of geometric charts with the bootstrap algorithm to improve the in-control performance of charts with smaller sample sizes. The simulation results show that the adjustment with the bootstrap algorithm improves the in-control performance of geometric charts by controlling the probability that the in-control average run length has a value greater than the desired one. The out-of-control performance of geometric charts with adjusted limits is also discussed.

Performance Tradeoff Between Control Period and Delay: Lane Keeping Assist System Case Study

  • Cha, Hyun-Jun;Park, Seong-Woo;Jeong, Woo-Hyuk;Kim, Jong-Chan
    • Journal of the Korea Society of Computer and Information
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    • v.20 no.11
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    • pp.39-46
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    • 2015
  • In this paper, we propose a performance-aware workload model for efficient implementation of control systems. When implementing a control algorithm as an embedded computer system, the control code executes periodically. For such systems, its control performance depends on not only the accuracy of the control algorithm itself but also temporal parameters such as control period and sensing to actuation delay. In this regard, this paper studies the relation between control period and delay by measuring and analyzing the control performance of LKAS (Lane Keeping Assist System) with varying period and delay combinations. Through this experimental study, this paper shows that the two timing parameters, i.e.,control period and delay, has a tradeoff relation in terms of control performance.

Optimum PI Controller Design for an Oil Cooler System Using GA (GA를 이용한 오일쿨러시스템의 최적 PI제어기 설계)

  • Jung, Young-Mi;Jeong, Seok-Kwon
    • Journal of Power System Engineering
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    • v.18 no.5
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    • pp.28-34
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    • 2014
  • This paper deals with optimum PI controller design using genetic algorithm to improve control performance and robustness for an oil cooler system. The optimum PI gain was found to minimize an object function, integrated absolute error, and to satisfy control design specifications such as overshoot and settling time based on practical transfer function of the oil cooler system. The control performance and robustness were investigated by comparing indicial responses and Bode diagram analysis with respect to three kinds of PI gains obtained from different gain decision manners. Moreover, the robustness against to input disturbances, sinusoidal wave form and abrupt single pulse, was evaluated. The computer simulation results showed that the suggested optimum gain can establish desirable control performance and strong robustness with easy design process.

Performance Analysis of Multirate LQG Control (멀티레이트 LQG 제어 기법의 성능 비교 분석)

  • 이진우;오준호
    • Journal of Institute of Control, Robotics and Systems
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    • v.5 no.2
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    • pp.123-130
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    • 1999
  • In discrete-time controlled system, sampling time is one of the critical parameters for control performance. It is useful to employ different sampling rates into the system considering the feasibility of measuring system or actuating system. The systems with the different sampling rates in their input and output channels are named multirate system. Even though the original continuous-time system is time-invariant, it is realized as time-varying state equation depending on multirate sampling mechanism. By means of the augmentation of the inputs and the outputs over one period, the time-varying system equation can be constructed into the time-invariant equation. The two multirate formulations have some trade-offs in the simplicity to construct the controller, the control performance. It is good issue to determine the suitable formulation in consideration of performance of them. In this paper, the two categories of multirate formulations will be compared in terms of the linear quadratic (LQ) cost function. The results are used to select the multirate formulation and the sampling rates suitable to the desired control performance.

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