• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.232-233
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• 2008

There are various large shocks in optical disc drive system like human touch and speak sound. In this paper, a nonlinear controller and a detection method are proposed. First, a relay nonlinear controller with dead zone is introduced. The structure of this nonlinear controller is simple and has a small amount of calculation. However, this controller has chattering problem when it is working. We suggest a disturbance detection algorithm using Kalman filter in this paper and it shows effective reduction of chattering. The proposed nonlinear controller using this detection algorithm had good performance for the shock.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.1
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• pp.1155-1161
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• 2001

We propose an adaptive nonlinear control algorithm for high precision tracking and stabilization of LOS(Line-of-Sight). The friction parameters of the LOS gimbal are estimated by off-line evolutionary strategy and the friction is compensated by estimated friction compensator. Especially, as the nonlinear control input in a small tracking error zone is enlarged by the nonlinear function, the steady state error is significantly reduced. The proposed algorithm is a direct adaptive control method based on the Lyapunov stability theory, and its convergence is guaranteed under the limited modeling error or torque disturbance. The performance of the pro-posed algorithm is verified by computer simulation on the LOS gimbal model of a moving vehicle.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.295-300
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• 2005

The freeplay, one of the concentrated structural nonlinearities, is inevitable for control surfaces of a real air vehicle due to normal wear of components and manufacturing mismatches. Also aerodynamic nonlinearities caused by a shock wave occur in transonic region. In practice, these nonlinearities induce the limit cycle oscillation (LCO) and decrease the transonic flutter speed. In this study, the fictitious mass method is used to apply a modal approach to nonlinear structural models due to freeplay. The transonic small-disturbance (TSD) equation is used to calculate unsteady aerodynamic forces in transonic region. Nonlinear aeroelastic time responses are predicted by the coupled time integration method (CTIM). This method was also applied to a 3D all-movable control wing to investigate its nonlinear aeroelastic responses. The angle of attack effect on the LCO characteristics has been found to be closely related with the initial pitching moment.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.1
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• pp.58-63
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• 2010

A new contact force estimation technique is proposed. Keeping the contact force at a certain level between finishing tool and the object is essential since the quality of the finished surface is very sensitive to the contact force during the finishing process. However, the contact force measurement cannot be obtained by simply installing load cells under machine table or in the middle of tool linkage. The reason is that the weight of the machine table and the tool linkage are much heavier than the force to be measured. To that end, a method for estimating disturbance is proposed for a system that is similar to the mechanism of the finishing machine, and the same method is applied to estimate the contact force of the brush-type finishing machine. To verify the effectiveness of the proposed method, a small scale test set-up has been built and the method has been tested.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.04a
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• pp.126-130
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• 2000

In this study, flutter characteristics of a composite wing have been studied for the variation of laminate angles in the subsonic, transonic and supersonic flow regime. The laminate angles are selected by the aspect of engineering practice such as 0, $\pm$45 and 90 degrees. To calculate the unsteady aerodynamics for flutter analysis, the Doublet Lattice Method(DLM) in subsonic flow and the Doublet Point Method(DPM) in supersonic flow are applied in the frequency domain. In transonic flow, transonic small disturbance(TSD) code is used to calculate the nonlinear unsteady aerodynamics in the time domain. Aeroelastic governing equation has been solved by v-g method in the frequency domain and also by Coupled Time-Integration Method(CTIM) in the time domain. from the results of present study, characteristics of free vibration responses and aeroelastic instabilities of a composite wing are presented for the set of various lamination angles in the all flow range.

• International Journal of Aeronautical and Space Sciences
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• v.10 no.1
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• pp.14-19
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• 2009

The typical aeroelastic analysis for a complex configuration such as a complete aircraft was done using the aerodynamic results of the wing and the structural modes of a complete aircraft; that is, the aerodynamics of a wing of a complete aircraft is assumed to be not much influenced by the body shape. Nevertheless, the body shape can cause a distortion of aerodynamic pressure on the wing surface and it is necessary to investigate the body effect in flutter analysis. In this reseasrch, MGM inverse design method is applied to include the body effect of a wing-body model which disturbs the pressure distribution on the wing surface.

• Childhood Kidney Diseases
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• v.16 no.1
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• pp.1-8
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• 2012

Nocturnal polyuria is one of the main pathogenic mechanisms of enuresis. Disturbance of circadian rhythm of antidiuretic hormone (ADH or AVP), hypercalciuria, and/or solute diuresis are considered to cause nocturnal polyuria, which in turn causes enuresis in patients with relatively small bladder capacity and high threshold for awakening. Evaluation of these factors would guide the therapeutic approach for enuresis.

• Journal of Energy Engineering
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• v.13 no.1
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• pp.40-50
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• 2004

Treatise that see executed investigation analysis about energy conservation technology, which skill move and skill class of introduction subject, transferㆍintroduction skill form, present condition of technology transferㆍintroduction and necessity etc. to energy conservation technology by program of Korea energy basis plan (1997∼2006) etc. Enforced company which questionnaire object achieves from the end 107 assignment practical used of energy conservation technology development propulsion assignment of Korea energy management corporation (KEMCO) to 1998-200 years and 416 companies related energy saving technology constructed to Korea Institute of Energy Research (KIER) database by post investigation and visit investigation. Question investigation result, transferㆍintroduction fields of energy conservation technology are industry sector, the enterprise size appeared with the fact that the small and medium enteifrise is many most. Also, technology transferㆍintroduction section is plan technique, form with technical cooperative form, amount of money 50,000,000 won under, appeared above 1 years in disturbance duration. In hereafter, technology transferㆍintroduction plan it appeared with the fact that the plan technique is many most.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.3
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• pp.363-369
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• 1999

In this paper, we design the robust $H_{\infty}$ controller for water level control of steam generator using a mixed $H_{\infty}$ optimization with model-matching method. Firstly we choose the desired model which has good disturbance rejection performance. Secondly we design a stabilizing controller to keep the model-matching error small and also provide sufficiently large stability margin against additive perturbations of the nominal plant. Simulation results show that proposed robust $H_{\infty}$ controller at specific power operation has satisfactory performances against the variations of load power, steam flow rate, primary circuit coolant temperature, and feedwater temperature. It can be also observed that the proposed robust $H_{\infty}$ controller exhibits better robust stability than conventional PI controller.

• 한국전산유체공학회:학술대회논문집
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• 2004.03a
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• pp.220-223
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• 2004

The initial conditions such as the film thickness and the void fraction at the onset of annular flow are required for the analytical dryout model. The Disturbance Wave Instability model(DWI model) is one of the model describing the Annular-to-Intermittent Flow regime Transition(AIFT). The experimental CHF conditions for the uniformly heated tube were compared with the predictions by the modified Levy model, for which the initial conditions at AIFT were estimated by the DWI model. For the flow through long tubes with small inlet subcooling, the effect of AIFT model on the dryout prediction was little. However, the use of DWI model gave better prediction of CHF in a short tube.