• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.189-192
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• 1996

This paper presents a systematic approach to identify a linguistic fuzzy model for a multi-input and single-output complex system. Such a model is composed of fuzzy rules, and its output is inferred by the simplified reasoning. The structure and membership function parameters for a fuzzy model are automatically and simultaneously identified by GA (Genetic Algorithm). After GA search, optimal parameters for the fuzzy model are finely tuned by a gradient method. A numerical example is provided to evaluate the feasibility of the proposed approach. Comparison shows that the suggested approach can produce the linguistic fuzzy model with higher accuracy and a smaller number of rules than the ones achieved previously in other methods.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1531-1536
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• 2003

In this paper the structure of 2-DOF controller based on artificial immune network algorithms has been suggested for nonlinear system. Up to present time, a number of structures of the 2-DOF controllers are considered as 2-DOF (2-Degrees Of Freedom) control functions. However, A general view is provided that they are the special cases of either the state feedback or the modification of PID controllers. On the other hand, The immune network system possesses a self organizing and distributed memory, also it has an adaptive function by feed back law to its external environment and allows a PDP (parallel distributed processing) network to complete patterns against the environmental situation, since antibody recognizes specific antigens which are the foreign substances that invade living creatures. Therefore, it can provide optimal solution to external environment. Simulation results by immune based 2-DOF controller reveal that immune algorithm is an effective approach to search for 2-DOF controller.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.1
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• pp.58-63
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• 1999

In this paper, We present a direction indicator algorithm for a mobile robot which uses VFF and neural networks. The structure of this neural network navigation system is composed of sensor system, backpropagation learning controllers for adjusting weight and the motion control system for real-time execution. The experimental results show that the direction indicator system operates properlv and strongly at any circumstance

• The Journal of the Acoustical Society of Korea
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• v.22 no.1E
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• pp.26-32
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• 2003

We propose new time-frequency (TF) tools for analyzing linear time-varying (LTV) systems and nonstationary random processes showing hyperbolic TF structure. Obtained through hyperbolic warping the narrowband Weyl symbol (WS) and spreading function (SF) in frequency, the new TF tools are useful for analyzing LTV systems and random processes characterized by hyperbolic time shifts. This new TF symbol, called the hyperbolic WS, satisfies the hyperbolic time-shift covariance and scale covariance properties, and is useful in wideband signal analysis. Using the new, hyperbolic time-shift covariant WS and 2-D TF kernels, we provide a formulation for the hyperbolic time-shift covariant TF symbols, which are 2-D smoothed versions of the hyperbolic WS. We also propose a new interpretation of linear signal transformations as weighted superposition of hyperbolic time shifted and scale changed versions of the signal. Application examples in signal analysis and detection demonstrate the advantages of our new results.

• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.73-75
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• 2005

The latest scientific highlights obtained with the Subaru telescope are given together with its current status and on-going instrumentation. We have been successfully operating the telescope and 8 observatory instruments (including an adaptive optics system) since January 1999, when the first light was accomplished. Open-use of Subaru began in December 2000. Subaru has a unique capability of its prime focus among other 8-10 meter class telescopes and has an excellent imaging performance as a result of its sophisticated active optics combined with the high stability of the sky at Mauna Kea. Scientific highlights are given on the discoveries of the most distant galaxies, spiral structure on a protoplanetary disk around AB Aur, and planetesimal belts in the debris disk around $\beta$ Pic. Brief summaries are given for three new instruments: the Multi-Object Infrared Camera and Spectrograph (MOIRCS), 188 element adaptive optics system, and Fiber Multi-Object Spectrograph (FMOS)

• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.109-112
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• 2005

We present the design, expected performance, and current status of the wide field near-infrared camera (OAOWFC) now being developed at Okayama Astrophysical Observatory, NAOJ, NINS. OAOWFC is a near-infrared survey telescope whose effective aperture is 91cm. It works at Y, J, H, and $K_s$ bands and is dedicated to the survey of long period variable stars in the Galactic plane. The field of view is $0.95 {\times} 0.95 deg^2$ which is covered by one HAWAII-2 RG detector of 2048 ${\times}$ 2048 pixels with the pixel size of $18.5 {\mu}m\;{\times}\;18.5{\mu}m$, that results in the sampling pitch of 1.6 arcsec/pixel. OAOWFC can sweep the area of $840 deg^2$ every 3 weeks, attaining a limiting magnitude of 13 in $K_s$ band. It allows us to observe long period variables embedded in the Galactic plane where interstellar extinction is severe in optical.

• Journal of the Korean Institute of Intelligent Systems
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• v.8 no.6
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• pp.106-118
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• 1998

The study concerns a design procedure of rule-based systems. The proposed rule-based fuzzy modeling implements system structure and parameter identification in the efficient from of "IF..., THEN..." statements, and exploits the theory of system optimization and fuzzy implication rules. The method for rule-based fuzzy modeling concerns the from of the conclusion part of the the rules that can be constant. Both triangular and Gaussian-like membership function are studied. The optimization hinges on an autotuning algorithm that covers as a modified constrained optimization method known as a complex method. The study introduces a weighted performance index (objective function) that helps achieve a sound balance between the quality of results produced for the training and testing set. This methodology sheds light on the role and impact of different parameters of the model on its performance. The study is illustrated with the aid of two representative numerical examples.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11a
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• pp.85-90
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• 1996

In this paper, the self-organizing fuzzy logic controller is developed for water level control of steam generator. In comparison with conventional fuzzy logic controllers, this controller performs control task with no control rules at initial and creates control rules as control behavior goes on, and also modifies its control structure when uncertain disturbance is suspected. Selected parameters in the fuzzy logic controller are updated on-line by the gradient descent loaming algorithm based on the performance cost function. This control algorithm is applied to water level control of steam generator model developed by Lee, et al. The computer simulation results confirm good performance of this control algorithm in all power ranges. This control algorithm can be expected to be used for automatic control of feedwater control system in the nuclear power plant with digital instrumentation and control systems.

• Journal of Sensor Science and Technology
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• v.7 no.6
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• pp.377-385
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• 1998

This paper describes the application of a coupled finite element-boundary element method to obtain the steady-state response of a hydrophone. The particular structure considered is a flooded piezoelectric spherical shell. The hydrophone is three-dimensionally simulated to transduce an incident plane acoustic pressure onto the outer surface of the sonar spherical shell to electrical potentials on inner and outer surfaces of the shell. The acoustic field formed from the scattered sound pressure is also simulated. And the displacement of the shell caused by the externally incident acoustic pressure is shown in temporal motion. The coupled FE-BE method is described in detail.

• Journal of the Korean Society of Systems Engineering
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• v.12 no.1
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• pp.25-40
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• 2016

The Systems Engineering (SE) approach is characterized by the application of a structured engineering methodology for the design of a complex system or component. In this study, the SE methodology is used to design a nondestructive inspection system for Bottom Mounted Instrumentation (BMI) nozzles. We developed a system that enables nondestructive inspection of BMI nozzles during regular refueling outage without removing the reactor internals. A special ultrasonic (UT) probe is introduced to scan and detect cracks within the weld region of the nozzle. A 3D model of the inspection structure system was developed along with the reactor pressure vessel (RPV) and internals which permits a virtual 3D simulation of the operation to check the design concept and effectiveness of the system and to provide a good visualization of the system. This approach allows for a virtual walk through to verify the proposed BMI nozzle inspection system.