• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 춘계학술대회 학술발표 논문집
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• pp.123-126
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• 1998

The theoretical foundations of GA are the Schema Theorem and the Building Block Hypothesis. In the Meaning of these foundational concepts, simple genetic algorithm(SGA) allocate more trials to the schemata whose average fitness remains above average. Although SGA does well in many applications as an optimization method, still it does not guarantee the convergence of a global optimum. Therefore as an alternative scheme, there is a growing interest in a co-evolutionary system, where two populations constantly interact and co-evolve in contrast with traditional single population evolutionary algorithms. In this paper, we propose a new design method of an optimal fuzzy logic controller using co-evolutionary concept. In general, it is very difficult to find optimal fuzzy rules by experience when the input and/or output variables are going to increase. So we propose a co-evolutionary method finding optimal fuzzy rules. Our algorithm is that after constructing two population groups m de up of rule vase and its schema, by co-evolving these two populations, we find optimal fuzzy logic controller. By applying the proposed method to a path planning problem of autonomous mobile robots when moving objects exist, we show the validity of the proposed method.

• 대한디지털의료영상학회논문지
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• 제12권2호
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• pp.81-87
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• 2010

The setting parameters of ultrasound scanner give influences to change of image. Sonographers have used a Matlab program to make Low Contrast Sensitivity(LCS) value and compared original images in order to evaluate the use of the supersonic diagnosis machinery. We confirmed the change of image in Grayscale values using Photoshop program. Experiment equipment of our research used A Medison Accuvix V10, A Multi-Tissue Ultrasound Phantom(040 GSE) of CHRIS Company, A Adobe Photoshop CS4 Program, A Convex Probe, A USB memory stick, A Probe Fixation Equipment. The method used Gain, Dynamic Range(DR) of the setting parameters of ultrasound scanner and researched Gain and DR was set to 10 dB. We changed the different settings to see the changes of images using Grayscale values of a Photoshop program about tissue images of a phantom. This study evaluated DR and Gain whether it is an image controller to get the optimum contrast to produce an image to see the how effect on the images. We did not use Gateway in supersonic diagnosis machinery. We can easily open to open the files through Photoshop program before we get Digital Imaging and Communications in Medicine(DICOM) files use USB memory stick in supersonic diagnosis machinery. When we diagnosed the lesion of the patient with ultrasound, the contrast and the Gray scale value of image are very important. In this research, we determined the optimum setting parameters that provided useful information to diagnose disease and evaluated the change of improved images.

• 한국정보처리학회논문지
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• 제6권4호
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• pp.952-958
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• 1999

본 논문에서는 유전자 알고리즘을 이용하여 퍼지 제어 시스템 설계 방법을 제안한다. 시스템의 성능 평가는 rise-time, settling time 그리고 overshoot와 같은 성능 매개변수를 이용하였다. 제안한 방법은 root-locus 방법을 사용한 제어 시스템과 비교하였다. 기존 제어 시스템은 제어기 설계시 수학적인 처리가 필요하다. 하지만 유전자 알고리즘을 이용한 제어기 설계는 수학적인 모델링을 할 필요가 없다. 그리고 일반적으로 시스템의 비선형 정도는 탐색에 의해서만 알수 있는 성질의 것이므로 본 논문에서는 최적의 탐색 알고리즘으로 널리 인정되고 있는 유전자 알고리즘을 사용하여 전역적인 규칙 공간을 탐색한 후 이를 바탕으로 퍼지 제어기를 완성한다. 제안된 제어 시스템의 효율성은 타스크 트래킹 위치 제어 시스템을 사용하여 안정, 불안정 시스템에서 컴퓨터 모의 실험을 통해서 입증된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 학술대회 논문집 전문대학교육위원
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• pp.187-190
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• 2002

In contrast to conventional electromagnetic motor, USM(Ultrasonic Motor), as piezoelectric ceramic applying ultrasonic mechanical vibration and as frictional-movement type motor, get rotational torque by elastic friction between stator and rotator, The USM, which is small motor without iron cores and coil as a simple structure, has little load weight, has character of high torque at low speed, and can apply a direct drive type without deceleration gear as low speed type. A response of USM from control input is satisfactory, and also generates much torque in low speed driving, and holding torque is much without supplying power. In this study, I designed and made Ultrasonic motor-digital multi controller(USM- DMC) using FPGA chip, A54SX72A made in Actel Corporation. By the minute, USM-DMC can control frequency, duty ratio, and phase difference of USM by llbit digital input from Pc. Therefore, when we use this controller, we can apply to typical parameter, frequency, phase difference, and voltage parameter, to control as well as we can do mixing control like phase-frequency, phase-voltage, frequency-voltage, frequency-phase-voltage, What is more, the strongest point is that it can trace frequency based on optimized frequency because we can input optimized resonant frequency while in motoring.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.741-745
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• 2001

Reliability and safety of steer-by-wire concepts can be achieved by redundant designs. This paper discusses the design of a fault tolerant concept for a force feedback actuator with a standard three-phase PMSM. In contrast to usual drives, the phases of the machine are separated electrically. This design allows driving the machine with two instead of three phases in case of a fault. A superimposed torque controller adjusts the influence of fault currents and torque harmonics in two-phase operation and guarantees smooth torque at the steering wheel

• 대한기계학회논문집
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• 제16권7호
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• pp.1307-1313
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• 1992

본 연구에서는 유연한 조작기의 끝점 위치 제어를 위해 LQG/LTR 제어법을 적 용함으로서 기존의 고전적 제어방법과 비교하고자 한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.315-317
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• 2006

In this paper, we design a terminal sliding mode controller based on neural network for nonlinear systems with uncertainties. Terminal sliding mode control (TSMC) method can drive the tracking errors to zero within finite time. Also, TSMC has the advantages such as improved performance, robustness, reliability and precision by contrast with classical sliding mode control. For the control of nonlinear system with uncertainties, we employ the self-recurrent wavelet neural network(SRWNN) which is used for the prediction of uncertainties. The weights of SRWNN are trained by adaptive laws based on Lyapunov stability theorem. Finally, we carry out simulations to illustrate the effectiveness of the proposed control.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(1)
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• pp.123-128
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• 1995

A classical PID controller is designed by applying the GA (Genetic Algorithm) which searches the optimal parameters through three major operators of reproduction, crossover and mutation under the given constraints. The GA could minimize the designer's interference and the whole design process could easily be automated. In contrast with other traditional PID design methods which allows for the system output responses only, the design with the GA can take account of the magnitude or the rate of change of control input together with the output responses, which reflects the more realistic situations. Compared with other PIDs designed by the traditional methods such as Ziegler and analytic, the PID by the GA shows the superior response characteristics to those of others with the least control input energy.

• 대한기계학회논문집B
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• 제25권9호
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• pp.1201-1208
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• 2001

Variable temperature anemometer(VTA) has greater sensitivity than a conventional constant temperature anemometer(CTA). In order to design a reliable VTA system, however, an elaborate photoconductive cell stabilizing circuit which plays a key role in setting wire-overheat ratio should be firstly developed. In this study, a stabilizing circuit which adopts proportional-integral analog controller was proposed and thoroughly tested for its accuracy and reproducibility. In contrast to the available circuit suggested by Takagi, the present circuit has characteristic that the resistance of a photoconductive cell increases with the increase of input voltage, which makes the current circuit very suitable for the design of VTA. Finally, VTA adopting stabilizing circuit was made and the enhanced sensitivity of the VTA was validated experimentally by comparing the calibration curves of VTA and CTA.

• 산업기술연구
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• 제20권B호
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• pp.201-206
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• 2000

A priori information of object is needed to control in some well known control methods. But we can't always know a priori information of object in real world. In this paper, the inverted pendulum is simulated as a control task with the goal of learning to balance the pendulum with no a priori information using neural network controller. In contrast to other applications of neural networks to the inverted pendulum task, the performance feedback is unavailable on each training step, appearing only as a failure signal when the pendulum falls or reaches the bound of track. To solve this task, the delayed performance evaluation and the learning of nonlinear of nonlinear functions must be dealt. Reinforcement learning method is used for those issues.