• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.7
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• pp.491-500
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• 2004

This paper considers a hybrid PWM(pulse width modulation) method which can be used in the brushless DC motor controller. Due to many disadvantages of bipolar PWM method, unipolar PWM method is mostly used in industrial field. In constant speed control application, the unipolar PWM method shows the good performance of speed control. But in the wide range of speed control application, it shows poor performance especially when deceleration is needed. So we propose the hybrid PWM method that utilizes both of bipolar and unipolar PWM methods according to the sign of the speed controller output. Simulation and experimental result show that the proposed method improves speed control performance of the brushless DC motor which is applied to the industrial sewing machines.

• Proceedings of the KIEE Conference
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• 2001.07e
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• pp.141-145
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• 2001

In this paper, model reference PID genetic controller was proposed in order to overcome the difficulty of reflecting control performance required in the overall control system and defects of the adaptation performance in the PID genetic controller. The proposed controller comprised Inner feedback loop consisting of the PID controller and plant, and outer loop consisting of an genetic algorithm which was designed for tuning a parameter of the controller. A reference model was used for design criteria of a PID controller which characterizes and quantizes the control performance required in the overall control system. Tuning parameter of the controller is performed by the genetic algorithm. The performance of proposed algorithm was verified through experiment for the DC servo motor.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.3
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• pp.218-228
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• 2001

The switched reluctance motor(SRM) has been increasingly used in high-performance servo applications such as electric vehicles, aircraft, and direct-drive robots. The dynamic equations of SRMs are, however, highly nonlinear and this makes it difficult to control SRMs with high performance. In this paper, we propose a new robust current tracking controller for SAMs which can compensate the nonlinear characteristics of SRM(i.e., back-emf and inductance) completely and hence shows perfect tracking performance even with an arbitrary small current control loop gain. Furthermore, even in case that there exist some model uncertainties, our current controller guarantees that the stator currents can track the reference current commands with sufficiently small tracking errors. In order to justify our work, we present the tracking performance analysis and some simulation results.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.3
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• pp.265-271
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• 1997

A fuzzy logic controller (FLC) has been widely used for many applications in recent years. But the relationship between control performance and design parameters has not been handled explicity in the conventional theory of fuzzy logic control. In this paper, based on the similarity between an FLC and a variable structure control (VSC) theory, a performance evaluation of an FLC, which gives quantitative accounts on the relationship is presented. The validity of the analysis is verified through extensive computer simulations.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.779-783
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• 2004

First this paper introduces an advanced FADEC (Full Authority Digital Electric Control) for current and future jet engines.It is designed to realize not only stable thrust control, but also performance improvement, reliability enhancement, service life extension, etc. It can be built by using current micro-processor with high computational power and there exists no difficulties but reliability problem of the micro- processor. Next, the simulation results of SFC minimization control are shown. The target engine is a supersonic, low-bypass ratio, 2-spool, combined cycle turbofan, designated as HYPR90T, which consists of a turbo engine for under Mach 3 flight and a ram engine for over Mach 3 flight. he results can then be used for performance optimization of the engine, which plays important role in the advanced FADEC.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2246-2248
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• 2001

This paper presents a new vector control scheme for induction motor. An exact knowledge of the rotor flux position is essential for a high-performance vector control. The position of the rotor flux is measured in the direct schemes and estimated in the indirect schemes. Since the estimation of the flux position requires a priori knowledge of the induction motor parameters, the indirect schemes are machine parameter dependent. The rotor and stator resistance among the parameters change with temperature. Variations in the parameters of induction machine cause deterioration of both the steady state and dynamic operation of the induction motor drive. Several methods have presented to minimize the consequences of parameter sensitivity in indirect scheme. In this paper, new estimation scheme of rotor flux position is presented to eliminate sensitivity due to variation in the resistance. The simulation is executed to verify the proposed vector control performance and to compare its performance with that of indirect and direct vector control.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.453-460
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• 2006

Stay cables, such as used in cable-stayed bridges, are prone to vibration due to their low inherent damping characteristics. Recently some studies have shown that active and semiactive control system using MR damper can potentially achieve both higher performance levels than passive control system and adaptability with few of the detractions. However, a control system including a power supply, controller, and sensors is required to maximize the performance of the MR damper and this complicated control system is not effective to most of large civil structures. This paper proposes a smart complex damping system which consists of toggle system and MR dampers by introducing electromagnetic induction(EMI) system as an external power source to MR damper. The performance of the proposed damping device has been compared with that of the passive-type control systems employing a MR damper, a linear viscous damper, and EMI system.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.511-518
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• 2006

In this study, seismic response mitigation effect of an MR damper generating response-dependent frictional force is investigated. It has been reported in previous studies that passively operated MR damper with constant input current doesn't show better control performance than semi-active MR damper with varying input current calculated by control algorithms such as linear quadratic regulator and sliding mode control. However, in order to operate the MR damper semi-actively, other control systems besides the damper itself such as sensors for measuring structural responses and controller for calculating optimal input current are necessary, which deteriorate the economical efficiency. This study presents a MR damper generating frictional force of which magnitude is controlled in accordance to the displacement and velocity transferred to the damper. Numerical analyses results indicate that the performance of the response dependent MR damper is closely related with the range of the friction force and it can be designed to short better control performance than the passive MR damper.

• Journal of Korean Society of Forest Science
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• v.113 no.2
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• pp.259-270
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• 2024

Since 2013, Korea has allocated significant budgets and manpower nationwide to prevent the spread of pine wilt disease and to reduce damage. As a result, the number of damaged trees decreased from 2.18 million in 2014 to 310,000 in 2021. However, the damage has increased again since then. Despite the overall decrease in the number of damaged trees, the scope of the damage continues to expand every year. Previous studies have develope In order to judge the control performance, a quantitative control performance analysis method to objectively evaluate control performance. This method takes into consideration two factors-quantity change and the change in the damage area, which is an area factor. This approach provides a more comprehensive assessment than the control guidelines that only suggest changes in damage grade based on the volume of damaged trees. The expansion of the damage range is also an important factor in analyzing control performance, but previous studies have not reflected this. Therefore, this study calculates the change in the distance of the pine wilt disease boundary area for Gyeongsangbuk-do, where changes in the damage range can easily be observed from year to year. The study then creates application criteria and coefficients and uses them to improves control performance index calculation formula. As a result, it was possible to calculate a quantitative analysis of the control performance, taking into account the changes in the damage range. When the improved formula was applied to 26 cities, counties, and districts in Gyeongsangbuk-do, it slightly decreased or increased compared to the existing calculation formula. This confirmed that the control performance index can change from a positive value (+), indicating increased damage, to a negative value (-), indicating reduced damage.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.19 no.1
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• pp.122-133
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• 2012

Purpose: The purpose of this study was to develop a web-based education program on control vancomycin-resistant enterococci (VRE) infections and to identify the effects of the program on knowledge and performance of nursing students. Methods: The web-based VRE infection control education program was developed by using the network-based instructional systems design model. The nursing students in the experimental group could access this web-based education program at any time, and as many times as they wanted, during the clinical training period. Effects were evaluated by assessing knowledge and performance of VRE infection control measures during the clinical training period. Results: The contents of the education program included diagnosis, transmission, and treatment of VRE, contact precautions, hand washing, personal protective equipment, environment management, and quizzes. The lecture portion was filmed in a virtual screen studio using flash animation, video, and sound effects, and it was uploaded on an internet site. The knowledge and performance scores of the experimental group after using the education program were significantly higher than those of the control group. Conclusion: The results suggest that the web-based VRE infection control education program is an effective educational method to enhance knowledge and performance of VRE infection control measures.