• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.1
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• pp.51-65
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• 2002

This paper presents a design method of the neural network-based controller using an indirect adaptive control method to deal with an intelligent control for chaotic nonlinear systems. The proposed control method includes the identification and control Process for chaotic nonlinear systems. The identification process for chaotic nonlinear systems is an off-line process which utilizes the serial-parallel structure of multilayer neural networks and simple state space neural networks. The control process is an on-line process which uses the trained neural networks as the system model. An error back-propagation method was used for training of identification and control for chaotic nonlinear systems. The performance of the proposed neural network controller was evaluated by application to the Duffing equation and the Lorenz equation, and the proposed controller was compared with other neural network-based controllers by computer simulations.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.8
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• pp.33-39
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• 2005

The maximum output torque and power developed by the machine is ultimately depended on the allowable inverter current rating and maximum voltage which the inverter can supply to the machine. Therefore, considering the limited voltage and current capacities, it is desirable to consider a control method which yields the best possible torque per ampere. In this paper, we propose fuzzy neural network(FNN) controller that combines a fuzzy control and the neural network for high performance control of induction motor drive. This controller composes antecedence of the fuzzy rules and consequence by a clustering method and a multi-layer neural networks. This controller is compounding of advantages that robust control of a fuzzy control and high-adaptive control of the neural networks. Also, this paper is proposed control of maximum torque per ampere(MTPA) of induction moor. This strategy is reposed which is simple in structure and has the honest goal of minimizing the stator current magnitude for given load torque. The performance of the proposed induction motor drive with maximum torque control using FNN controller is verified by analysis results at dynamic operation conditions.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.4
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• pp.291-299
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• 2007

To operate a permanent magnet synchronous motor (PMSM) at a maximum torque per ampere (MTPA) operation point, the exact values of machine parameters such as inductances and back-EMF constant, which are sensitive to motor phase currents and temperature respectively, should be blown. An adaptive estimation method for on-line estimation of the machine parameters is not suitable for practical applications since it has difficulties in estimating exact values and requires complex mathematical calculations. The purpose of this paper is to present a simple MTPA operation point tracking control strategy for vector controlled PMSM drives with slow dynamic loads. The proposed method searches MTPA operation points by modulating current phase angle and observing the variation in command power. The current angle modulation strategy is designed to sense the effect of load variations in the command power. Therefore, the proposed method can track the MTPA operation points of the PMSM regardless of load variations. Computer simulation and experimental study is also presented to show the effectiveness of the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.354-354
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• 2000

In this paper, we would study the applicability of neural networks to the recognition process of Korean stenographic character image, applying the classification function, which is the greatest merit of those of neural networks applied to the various pans so far, to the stenographic character recognition, relatively simple classification work. Korean stenographic recognition algorithms, which recognize the characters by using some methods, have a quantitative problem that despite the simplicity of the structure, a lot of basic characters are impossible to classify into a type. They also have qualitative one that it is not easy to classify characters for the delicacy of the character forms. Even though this is the result of experiment under the limited environment of the basic characters, this shows the possibility that the stenographic characters can be recognized effectively by neural network system. In this system, we got 90.86% recognition rate as an average.

• Journal of Korean Institute of Industrial Engineers
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• v.41 no.4
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• pp.389-395
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• 2015

According to much research on cognitive science, the impact of the scene-context on human visual search in real-world images could be as important as the saliency. Therefore, this study proposed a method of Adaptive Control of Thought-Rational (ACT-R) modeling of visual search in real-world images, based on saliency and scene-context. The modeling method was developed by using the utility system of ACT-R to describe influences of saliency and scene-context in real-world images. Then, the validation of the model was performed, by comparing the data of the model and eye-tracking data from experiments in simple task in which subjects search some targets in indoor bedroom images. Results show that model data was quite well fit with eye-tracking data. In conclusion, the method of modeling human visual search proposed in this study should be used, in order to provide an accurate model of human performance in visual search tasks in real-world images.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.153-157
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• 2009

A Highly efficient Mercury-free Flat Fluorescent Lamp (MFFL) with dielectric barrier Xe gas discharge was developed for an alternative of conventional line-type Cold Cathode Fluorescent Lamps (CCFLs) which shows a wide voltage margin and a stable discharge operation for diffuse glow discharge with an application of a auxiliary electrode. Electro-optic characteristics of the MFFL were examined through the changes in ambient temperature, total pressure and Xe partial pressure. the single cell is expanded into a multi-structured configuration to realize a large sized lamp by a simple repetition of the single cells, and a new driving scheme is proposed for an adaptive brightness control using dual auxiliary electrodes and bi-polar drive scheme. In addition, interesting application of this ultra high luminance flat lamp by the optimization of the gas condition and the pattern of the rear phosphor layer is suggested as a good alternative of daylight lamp source

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.9
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• pp.983-989
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• 2014

In this paper, a new active noise control method was proposed to decrease a weight of car, and to increase a fuel efficiency and to provide passengers' comfort and calmness, instead of a passive noise control method such as sound absorbing and insulating materials. The proposed method is an enhanced active noise controller operating by a bidirectional control algorithm. The algorithm is simple to implement and available to analyze mathematically with nearly equivalent complexity of computation. Through simulations for engine noises of a car, the proposed controller was verified that its performances of time and frequency domain were superior to those of both feedforward and feedback controllers, and it had better capability of controlling the noises when the impulsive disturbance was flow in and the response of secondary path was varied.

• The KIPS Transactions:PartB
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• v.12B no.2 s.98
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• pp.157-166
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• 2005

In 3D virtual environment the description of character' s movement that has utilized the conventional key-frame technique is gradually being developed toward the application of motion control method to generate more realistic and natural motion. Even the motion control method, however, has the limitation for expression of character's motion adapted to the ground properties of virtual world. That is, the walking motions of character are not only, for the most part, so uniform simple and repeated often as to feel to be tedious, but also the unnatural motion in which the tips of the toes soak through a plane or float in the air discording with the conditions of terrain lowers the semblance of reality. This paper proposes an adaptive motion control method for human figure locomotion in virtual environments or games, in which the walking motion is dynamiccally adapted to the ground's sliding properties. We compute an optimal parameters for one cycle of walking motion adapted to the ground properties by combining the coefficient of friction and centripetal force, and therefrom we induce a set of nonskid speed corresponding to various sliding properties of the ground.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.6
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• pp.1881-1900
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• 2014

Since 802.11 wireless LANs are so widely used, it has become common for numerous access points (APs) to overlap in a region, where most of those APs are managed individually without any coordinated control. This pattern of wireless LAN usage is called the private OBSS (Overlapping Basic Service Set) environment in this paper. Due to frame collisions across BSSs, each BSS in the private OBSS environment suffers severe performance degradation. This study approaches the problem from the perspective of congestion control rather than noise or collision resolution. The retry limit, one of the 802.11 attributes, could be used for traffic control in conjunction with TCP. Reducing the retry limit causes early discard of a frame, and it has a similar effect of random early drops at a router, well known in the research area of congestion control. It makes the shared link less crowded with frames, and then the benefit of fewer collisions surpasses the penalty of less strict error recovery. As a result, the network-wide performance improves and so does the performance of each BSS eventually. Reducing the retry limit also has positive effects of merging TCP ACKs and reducing HOL-like blocking time at the AP. Extensive experiments have validated the idea that in the OBSS environment, reducing the retry limit provides better performance, which is contrary to the common wisdom. Since our strategy is basically to sacrifice error recovery for congestion control, it could yield side-effects in an environment where the cost of error recovery is high. Therefore, to be useful in general network and traffic environments, adaptability is required. To prove the feasibility of the adaptive scheme, a simple method to dynamically adjust the value of the retry limit has been proposed. Experiments have shown that this approach could provide comparable performance in unfriendly environments.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.2
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• pp.36-40
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• 1993

In order to improve complicated construction and complex control which are disadvantage of optimal PWM technique aimed at harmonic elimination method, this paper presented MRA(Model Reference Adaptive) PWM technique that gatmg signal of inverter is generated by comparing the reference signal with the induced feedback signal at the reference model of load. Design of controller is composed of microprocessor and analog circuit. MRA PWM technique used in the paper is able to compensate the degradation of voltage efficiency to be generated by the ratio of the output voltage to the DC supply voltage being low for using conventional sinusoidal PWM technique. When the trapezoidal signal is employed as the reference signal. the low order harmonics of line current can be reduced and the switching pattern is made by on-line computation using comparatively simple numerical analysis.