• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1382-1386
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• 2003

In this paper, we propose a controller for the position of a cart and the angle of a pendulum. To achieve both purposes simultaneously, we divide the system into the dominant subsystem and the dominated one after partial feedback linearization. The proposed controller is composed of a nonlinear controller stabilizing the dominant subsystem and a linear quadratic controller. Using the proposed controller, the controllable region is increased by the nonlinear control part and the control input minimized by the linear control part (LQR).

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1994.10a
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• pp.167-174
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• 1994

In this study, an improved response surface method is proposed. By using gradient projection method, the sampling points for creating response surface are evaluated at the region close to the failure surface. This points are combined with linear response surface function and Rackwitz-Fiessler algorithm. Also, a method controlling the range of selecting sampling points considering the non-linearity of the limit states is proposed to reduce the error produced by approximating the non-linear limit state to linear response surface. With the examples the result of the proposed method is found to be more accurate and efficient than the previous response surface method.

• Proceedings of the IEEK Conference
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• 2000.11d
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• pp.73-76
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• 2000

A Scene Based Technique(SBT) that corrects linear array infrared detector's nonuniformity is proposed. Basically, this technique dispenses with using temperature references on a linear array infrared detector. To correct the nonuniformity of infrared images, we use three methods. Firstly, we detect bad channels by using the information which is cumulated all the same line pixels. Secondly, a variable window method is applied to compensate more accurately. Thirdly, an adaptive method which updates gain and offset coefficient is used only on a stationary region. These results are demonstrated on a computer simulation with various images. As a result, the nonuniformity is corrected completely, so that images are enhanced and PSNR(peak signal to noise ratio) is improved much.

• Journal of Industrial Technology
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• v.10
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• pp.69-72
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• 1990

In this paper the numerical method for the study of wave reflection from and transmission through submerged permeable breakwaters using the boundary element method is developed. The numerical analysis technique is based on the wave pressure function instead of velocity potential because it is difficult to define the velocity potential in the each region arising the energy dissipation. Also, the non-linear energy dissipation within the submerged porous structure is simulated by introducing the linear dissipation coefficient and the tag mass coefficient equivalent to the non-linear energy dissipation. For the validity of this analysis technique, the numerical results obtained by the present boundary element method are compared with those obtained by the other computation method. Good agreements are obtained and so the validity of the present numerical analysis technique is proved.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.729-731
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• 2004

This paper deals with the design of a low order $H_{\infty}$ controller by using an iterative linear matrix inequality (LMI) method. The low order $H_{\infty}$ controller is represented in terms of LMIs with a rank condition. To solve the non-convex rank-constrained LMI problem, a linear penalty function is incorporated into the objective function so that minimizing the penalized objective function subject to LMIs amounts to a convex optimization problem. With an increasing sequence of the penalty parameter, the solution of the penalized optimization problem moves towards the feasible region of the original non-convex problem. The proposed algorithm is, therefore, convergent. Numerical experiments show the effectiveness of the proposed algorithm.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.190-198
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• 2002

In switched reluctance motor(SRM) drive, it is necessary to synchronize the stator phase excitation with the rotor position. Therefore the rotor position information is an essential. Usually optical encoders or resolvers are used to provide the rotor position information. These sensors are expensive and are not suitable for high speed operation. In general, the accuracy of the switching angles is dependent upon the resolution of the encoder and the sampling period of the microprocessor. But the region of high speed, switching angles are fluctuated back and forth from the preset values, witch are cause by the sampling period of the microprocessor. Therefore, the low cost linear encoder suitable for the practical and stable SRM drive is proposed and the control algorithm to provide the switching signals using the simple digital logic circuit is also presented in this paper It is verified from the experiments that the proposed encoder and logic controller can be a powerful candidate for the practical low cost SRM drive.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.794-798
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• 2002

This paper deals with a moving coil type linear motor for fast access of the miniature ODD. This slim-line motor is composed of the mover supported by guide mechanism, the coil wound into it, and the yoke attached to the permanent magnet for stator. The driving force is generated by the PM of the stator and the current in the coils of the mover. Magnetic circuit analysis and Finite Element Method are applied to estimate the thrust force at air gap. In order to compare the force characteristics between two methods, various experiment results are applied to verify on a prototype. Also the flexible modes of the motor are predicted through the FEM and the structural components are modified to locate this on high frequency region.

• Journal of the Korean Applied Science and Technology
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• v.28 no.4
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• pp.386-392
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• 2011

We are crystallized to the linear low density polyethylene(LLDPE) particles by a thermally induced phase separation(TIPS). TIPS process based on the phase separation mechanism was performed for the LLDPE system which undergoes liquid-solid phase separation. The linear low density polyethylene particle formation occurred by the nucleation and growth mechanism in the metastable region. Although the growth rates depended on the experimental conditions such as the polymer concentration and temperature, the particles were larger when the polymer concentration was higher or temperature was higher. The particles were observed by SEM. The LLDPE particle size distribution became broader when the polymer concentration was higher.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.11
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• pp.747-752
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• 2004

This paper presents an iterative linear matrix inequality (LMI) approach to the design of a static output feedback (SOF) stabilization controller. A linear penalty function is incorporated into the objective function for the non-convex rank constraint so that minimizing the penalized objective function subject to LMIs amounts to a convex optimization problem. Hence, the overall procedure results in solving a series of semidefinite programs (SDPs). With an increasing sequence of the penalty parameter, the solution of the penalized optimization problem moves towards the feasible region of the original non-convex problem. The proposed algorithm is, therefore, convergent. Extensive numerical experiments are Deformed to illustrate the proposed algorithm.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.12
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• pp.595-601
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• 2003

For a control of CPS(Contactless Power Supply), the paper deals with the results which are simulated by a equivalent electric circuit on the LIPT(Linear Inductive Power Transmission). In order to control the CPS, the output values is handled with the driving frequency according to the change of a load. The method that controls the driving frequency for adjusting the output power is reasonable to be applied to the controller. But, when the driving frequency meets the resonant frequency and passes, it lead to a serious problem. Therefore, the controlled region of the driving frequency has to be predicted and determined by the simulation of a electric circuit.