• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.965-967
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• 2003

Fuzzy Controller is a system that displays a person's thoughts using membership function and IF-THEN rules. With the help of specialists' knowledge, rule bases can be explained in easy language. Furthermore Fuzzy Controller has strong resistance against turbulence. Its performance is especially prominent when targets cannot be measured in mathematic methods because the fuzzy controller can measure the output using only the relations between the input and output. With the increasing influence of multimedia on our daily lives, vision plays bigger role both in industries and personal lives. Like wise vision is being used in many areas such as detecting and identifying objects. It is difficult to detect and control targets because there is a delay in the calculating when using vision in detecting and controlling objects in large quantity. In this paper we showed how to use fuzzy controller in minimizing the calculation process, controlling target objects and moving view window instead of applying input variation through vision. Ball beam, which has strong nonlinear, was used as the target object and DSP320C6711 IDK by TI(Texas Instruments) company was for the benefit of speedy calculation and vision data operation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.4
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• pp.427-433
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• 2010

With recent increased demand for reverse engineering in dental machining, the 3D laser scanner is widely used for inspection of artificial pontic. In order to overcome the optical drawback of laser scanner, such as irregular scatter, direction of beam, and the influence of surface integrity, it is developed in this study a new 3D measuring system for artificial pontic using spherical coordinate system mechanism by point laser sensor, which keeps the direction of beam normal to surface consistently. The comprehensive integrated system is established to evaluate the improvement of accuracy with data acquisition system. The experimental results for measuring a master ball and pontic models shows the excellent form accuracy and repeatability compared with conventional apparatus. Also, these results shows the possibility to apply this system for the measuring purpose within 0.05mm accuracy of pontic at the sharp edge or margin contour, which was difficult to measure at the conventional systems.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.5
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• pp.1208-1217
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• 1993

The simple and effective optical technique synthesizing holographic interferometry and speckle photography is presented. The optical system used in this experiment is based on image holography. A cantilever beam located on the precision translator is used to evaluate this measurement system. Experimental results agree well with the actual displacements within the error of 2.8%. As an its application, three dimensional contact deformation in the ball indentation is measured by using this optical system and compared with the numerical analysis by finite element method.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.179-184
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• 1998

In this paper, a new hierarchical fuzzy inference system (HFIS) using structured Takagi-Sugeno type fuzzy inference units(FIUs) is proposed. The proposed HFIS not only solves the rule explosion problem in conventional HFIS, but also overcomes the readability problem caused by the structure where outputs of previous level FIUs are used as input variables directly. Gradient descent algorithm is used for adaptation of fuzzy rules. The ball and beam control is performed in computer simulation to illustrate the performance of the proposed controller.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2201-2210
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• 2000

Vibration of a rotating disk-spindle system is analyzed by using Hamilton's principle, FEM and substructure synthesis. A rotating disk undergoes the rigid body motion and the elastic deformation. It s equation of motion is derived by Kirchhoff plate theory and von Karman nonlinear strain. A rotating shaft is described by Rayleigh beam theory considering the axial rigid body motion. The stationay shaft supporting the rotating disk-spindle-bearing system is modeled by Euler beam theory, and the stiffness of ball bearing is determined by A.B.Jones' theory. FEM is used to solve the derived governing equations, and substructure synthesis is introduced to assemble each structure of the rotating disk-spindle system. The developed theory is applied to the spindle system of a 35' computer hard disk drive with 3 disks to verify the simulation results. The simulation results agree very well with the experimental ones. The proposed theory may be effectively expanded to the complex structure of a disk-spindle system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.6
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• pp.1182-1189
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• 1994

In this paper, we evaluate the performance of a fuzzy controller with a self-learning structure. The fuzzy controller is based on a fuzzy logic that approximates and effectively represents the uncertain phenomena of the real world. The fuzzy controller has control of a plant with a fuzzy inference logic. However, it is not easy to decide the membership function of a fuzzy controller and its controlrule. This problem can be solved by designing a self-learning controller that improves its own contropllaw to its goal with a performance table. The fuzzy controller is implemented with a 386PC, an interface board, a D/A converter, a PWM(Pulse Width Modulation) motor drive-circuit, and a sensing circuit, for error and differential of error. Since a Ball and Beam System is used in the experiment, the validity of the fuzzy controller with the self-learning structure can be evaluated through the actual experiment and the computer simulation of the real plant. The self-learning fuzzy controller reduces settling time by just under 10%.

• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.40-48
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• 1995

$TiB_2$-TiN double-layer coating have been prepared by ion beam enhanced deposition. AES, XRD, TEM and HRTEM were employed to characterize the $TiB_2$ layer. The microhardness of the coatings was evaluated by an ultra low-load microhardness indenter system, and the tribological behavior was examined by a ball-on-disc tribology wear tester. It was found that in a single titanium diboride layer, the composition is uniform along the depth of the film, and it is mainly composed of nanocrystalline $TiB_2$ with hexagonal structure, which resulted from the ion bombardment during the film growth. The hardness of the $TiB_2$ films increases with increasing ion energy, and approaches a maximum value of the $TiB_2$ films increases with increasing ion energy, and approaches a maximum value of 39 Gpa at ion energy of 85 keV. The tribological property of the TiB2 films is also improved by higher energy of 85keV. The tribological property of the $TiB_2$ films is also improved by higher energy ion beam bombardment. There is no major disparity in the mechanical properties of double-layer $TiB_2$/TiN coatings and TiN/$TiB_2$ coatings. Both show an improved wear resistance compared with single-layer $TiB_2$ films. The adhesion of double-layer coatings is also superior to that of single-layer films.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.243-246
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• 1994

In this paper, a self-learning fuzzy controller is designed with a fuzzy approximation of an inverse model. The aim of an identification is to find an input command which is control of a system output. It is intuitional and easy to use a classical adaptive inverse modeling method for the identification, but it is difficult and complex to implement it. This problem can be solved with a fuzzy approximation of an inverse modeling. The fuzzy logic effectively represents the complex phenomena of the real world. Also fuzzy system could be represented by the neural network that is useful for a learning structure. The rule of a fuzzy inverse model is modified by the gradient descent method. The goal is to be obtained that makes the design of fuzzy controller less complex, and then this self-learning fuzz controller can be used for nonlinear dynamic system. We have applied this scheme to a nonlinear Ball and Beam system.

• The KIPS Transactions:PartA
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• v.8A no.1
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• pp.56-62
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• 2001

This paper presents a neural network based variable structure control scheme for nonlinear systems. In this scheme, a set of local variable structure control laws are designed on the basis of the linear models about preselected representative points which cover the range of the system operation of interest. From the combination of the set of local variable structure control laws, neural networks infer the approximate control input in between the operating points. The neural network based variable structure control alleviates the effects of model uncertainties, which cannot be compensated by the control techniques using feedback linearization. It also relaxes the discontinuity in the system’s behavior that appears when the control schemes based on the family of the linear models are applied to nonlinear systems. Simulation results of a ball and beam system, to which feedback linearization cannot be applied, demonstrate the feasibility of the proposed method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.784-789
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• 2000

Equations of motion are derived and solved using the finite element method substructure synthesis for the disk-spindle system with rigid spindle and flexible shaft. The disk is modeled as a flexible spinning disk by Kirchhoff plate theory and von Karman nonlinear strain. The spindle supporting the flexible disk is modeled as a rigid body to consider its complex geometry. The stationary shaft supporting the rotating disk-spindle-bearing system is modeled by Euler beam, and the ball bearings are modeled as the stiffness matrix with 5 degrees of freedom. Developed theory is applied to analyze the vibration characteristics of a 3.5" HDD and a 2.5" HDD, respectively, and modal tests are performed to verify the simulation results. This paper shows that the developed theory can be effectively applied to the rotating disk-spindle system with the spindle of complex shape.