• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2584-2586
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• 2000

A drum level control is one of the most important control systems in thermal power plant. The control objective of drum level of boiler in thermal power plant is to maintain drum level at constant set-point regardless of disturbance such as main steam flow. The implemented drum level controller is the cascade PI controller. The important factor in drum level controller is the parameters of two PI controllers. The tuning of PI controller parameter is tedious and time-consuming job. In this paper, the relay feedback Ziegler - Nichols tuning method extended to auto-tune cascade PI drum level controller. Finally, the simulation result using boiler model in Power Plant shows the validity of auto-tuned cascade PI controller.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1663-1674
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• 2017

This paper deals with the robust speed regulation of a surface-mounted permanent magnet synchronous motor (SPMSM) that is subject to parametric uncertainties and external disturbances. The proposed approach retains a conventional cascade control configuration composed of an outer-loop speed control module and inner-loop current control modules. Baseline proportional-integral (PI) controllers are designed for nominal modular systems without accounting for the uncertainties to set a desired control performance of the closed-loop system. After studied in both frequency and time domains, a reduced-order proportional-integral observer (PIO), as a modular disturbance observer, is incorporated with each control module to maintain the ideal performance of the modules. Theoretical analysis confirms the desired performance recovery of the augmented system with modular PIOs to the nominal system. Comparative computer simulations and experimental results validate the proposed cascade control method for SPMSM speed regulation.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.271-272
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• 2014

비례-적분(PI) 제어기는 전동기의 간섭성분을 고려하지 않기 때문에 고속회전영역에서 오버슈트가 커지고, 적분기 포화로 인해 정착 시간이 느려지는 단점이 있다. 고속회전영역에서 느린 응답성을 보완하기 위해 전동기의 간섭성분을 고려하는 Cascade PI 전류제어기가 제안되었지만 오버슈트를 증가시키는 문제점이 발생한다. 본 논문에서는 Cascade PI 제어기를 소개하고 Cascade PI 제어기의 오버슈트 특성을 개선하기 위한 전류제어기를 제안하였다. 시뮬레이션을 통하여 각 제어기의 성능을 비교, 분석하였으며 실험을 통해 이를 검증하였다.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.458-460
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• 1998

The drum level control is initiated by 1-element manual control, and then the control mode is changed to 1-element automatic control mode. Finally, the drum level control is changed to 3-element automatic control mode by the logic based on pre-defined threshold of main steam flow. In terms of plant automation, the automatic 1-element control mode is required from the start-up of boiler. In this paper, the fuzzy controller is adopted for automatic 1-element control of drum level from start-up. It is suggested that the fuzzy controller is used in 1-element control, and the fuzzy-PI cascade controller is used in 3-element control. Finally, the validity of suggested control scheme is shown via simulation.

• Journal of Ocean Engineering and Technology
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• v.33 no.2
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• pp.139-145
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• 2019

It is important that an MGO Chiller System, which is one of the sulfur oxide emission control technologies, is designed to meet the fuel temperature requirements, even with sudden engine load changes. Three different control algorithms (PI, Cascade, and MPC) were applied to an indirect MGO chiller system to compare and analyze the outlet temperature dynamic characteristics of the system through a case study. The results showed that the MPC control method had the best temperature following characteristics in the case study, and the temperature deviation range was reduced by approximately 5% compared to the PI control method.

• International Journal of Advanced Culture Technology
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• v.5 no.1
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• pp.51-57
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• 2017

Digital signage is becoming part of daily life across a wide range of visual advertisements segments market used in stations, hotels, retail stores, hotels, etc. The current digital signage system used in market is generally works on limited user interactivity with static contents. In this paper, a new approach is proposed using computer vision based dynamic audience adaptive cost-effective digital signage system. The proposed design uses the Camera attached Raspberry Pi Open source platform to employ the real-time audience interaction using computer vision algorithms to extract facial features of the audience. The real-time facial features are extracted using Haar Cascade algorithm which are used for audience gender specific rendering of dynamic digital signage content. The audience facial characterization using Haar Cascade is evaluated on the FERET database with 95% accuracy for gender classification. The proposed system, developed and evaluated with male and female audiences in real-life environments camera embedded raspberry pi with good level of accuracy.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.7
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• pp.567-573
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• 2001

A real-time HVAC system is proposed which implements real-time control of thermal environment for virtual reality. It consists of a pair of hot and cold loops that serve as thermal reservoirs, and a mixing box to mix hot and cold air streams flowing if from loops. Their flow rates are controlled in real-time to meet a set temperature and flow rate. A cascade control algorithm along with gain scheduling is applied to the system and test results shows that the closed-loop response approached set values within 3 to 4 seconds.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.154-159
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• 1988

In this paper, a hyperstable cascade control scheme for servo drive systems is proposed to reduce the chattering, which is an undesirable property in discontinuously controlled systems. First, a discontinuously controlled hyperstable MRAC scheme is designed with respect to PI speed control system using only output variables, and then a linear position controller is cascaded. It is shown that the above system is asymptotically stable and the chattering is greatly reduced at a constant speed provided that the disturbance torque satisfies a certain condition.

• Journal of Power System Engineering
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• v.18 no.5
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• pp.129-136
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• 2014

This paper proposes improvement on sensorless vector control performance of a permanent magnet synchronous motor (PMSM) with sliding mode observer. An adaptive observer gain and second order cascade low-pass filter (LPF) were used to improve the estimation accuracy of the rotor position and speed. The adaptive observer gain was applied to suppress the chattering intensity and obtained by using the Lyapunov's stability criterion. The second order cascade LPF was designed for the system to escalate the filtering performance of the back-emf estimation. Furthermore, genetic algorithm was used to optimize the system PI controller's performance. Simulation results showed the effectiveness of the suggested improvement strategy. Moreover, the strategy was useful for the sensorless vector control of PMSM to operate on the low-speed area.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.10
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• pp.947-959
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• 2001

We propose a control scheme to control the indoor zone temperature via variable air volume (VAV) unit. To control the room temperature, state space model of the conditioned zone which is partitioned into nine artificial sectional regions is derived. The nonlinearity of the damper motion and actuator are considered for the practical use in the state space system description. The temperature control of the room temperature is performed by manipulating the degree of openness of the damper in relation to the local room temperature and the supplied air flow rate. In general, since a local temperature in the conditioned zone is measured, it is required to estimate the temperature values in each regions for the precise temperature control. We thus design a state observer to estimate the regional temperature, and use these values in the controller. The overall control system consists of the state observer based state feedback with the integral control. We compared the control results of the proposed scheme with those of cascade proportional and integral (PI) control, and showed that the scheme achieved precise control of the conditioned system.