• Journal of applied mathematics & informatics
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• v.22 no.1_2
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• pp.373-385
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• 2006

To solve a class of nonlinear parameter estimation problems, a method combining the regularized structured nonlinear total least norm (RSNTLN) method and parameter separation scheme is suggested. The method guarantees the convergence of parameters and has an advantages in reducing the residual norm over the use of RSNTLN only. Numerical experiments for two models appeared in signal processing show that the suggested method is more effective in obtaining solution and parameter with minimum residual norm.

• Communications for Statistical Applications and Methods
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• v.24 no.6
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• pp.651-662
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• 2017

We propose an alternative procedure to select penalty parameter in $L_1$ penalized robust regression. This procedure is based on marginalization of prior distribution over the penalty parameter. Thus, resulting objective function does not include the penalty parameter due to marginalizing it out. In addition, its estimating algorithm automatically chooses a penalty parameter using the previous estimate of regression coefficients. The proposed approach bypasses cross validation as well as saves computing time. Variable-wise penalization also performs best in prediction and variable selection perspectives. Numerical studies using simulation data demonstrate the performance of our proposals. The proposed methods are applied to Boston housing data. Through simulation study and real data application we demonstrate that our proposals are competitive to or much better than cross-validation in prediction, variable selection, and computing time perspectives.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.4
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• pp.1-6
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• 2010

In this paper, we present a new delay-dependent and parameter-dependent robust stability condition for uncertain singular systems with polytopic parameter uncertainties and time-varying delay. The robust stability criterions based on parameter-dependent Lyapunov function are expressed as LMI (linear matrix inequality). Moreover, the proposed robust stability condition is a general algorithm for both singular systems and non-singular systems. Finally, numerical examples are presented to illustrate the feasibility and less conservativeness of the proposed method.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.6
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• pp.517-523
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• 2006

This paper is focused on a robust saturation controller for the stable linear time-invariant (LTI) system involving both actuator's saturation and structured real parameter uncertainties. Based on affine quadratic stability and multi-convexity concept, a robust saturation controller is newly proposed and the linear matrix inequality (LMI)-based sufficient existence conditions for this controller are presented. The controller suggested in this paper can analytically prescribe the lower and upper bounds of parameter uncertainties, and guarantee the closed-loop robust stability of the system in the presence of actuator's saturation. Through numerical simulations, it is confirmed that the proposed robust saturation controller is robustly stable with respect to parameter uncertainties over the prescribed range defined by the lower and upper bounds.

• Smart Structures and Systems
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• v.28 no.6
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• pp.791-798
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• 2021

Current investigation aims to analyze the characteristics of magnetohydrodynamic boundary layer flow of bioconvection Casson fluid in the presence of nano-size particles over a permeable and non-linear stretchable surface. Fluid passes through the Darcy-Forchheimer permeable medium. Effect of different parameter such as Darcy-Forchheimer, porosity parameter, magnetic parameter and Brownian factor are investigated. Increasing Brownian factor leads to the rapid random movement of nanosize particles in fluid flows which shows an expansion in thermal boundary layer and enhances the nanofluid temperature more rapidly. For large values of Darcy-Forchheimer, magnetic parameter and porosity factor the velocity profile decreases. Higher values of velocity slip parameter cause decreasing trend in momentum layer with velocity profile.

• Journal of computational fluids engineering
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• v.13 no.4
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• pp.96-106
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• 2008

We review a series of studies on turbulent skin friction drag reduction in wall-turbulence recently conducted in Japan. First, an identity equation relating the skin friction drag and the Reynolds shearstress (the FIK identity) is introduced. Based on the implication of the FIK identity, a new analytical suboptimal feedback control law requiring the streamwise wall-shear stress only is introduced and direct numerical simulation (DNS) results of turbulent pipe flow with that control is reported. We also introduce DNS of an anisotropic compliant surface and parameter optimization using an evolutionary optimization technique.

• 한국연소학회:학술대회논문집
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• 2000.05a
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• pp.76-84
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• 2000

A numerical study was conducted for the investigation of thermal choking process in a model scramjet engine based on the experimental results at the Australian National University. The results of numerical simulation showed that thermal choking process could be related to the interaction between hypersonic flow and fuel-air mixing process. Especially, we could make sure that turbulent mixing was most important parameter to the thermal choking process.

• Journal of applied mathematics & informatics
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• v.26 no.5_6
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• pp.1123-1132
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• 2008

In this paper, by introducing a parameter, we establish a new Ostrowski's integral inequality which generalizes the result of [5]. Finally, we apply the new Ostrowski's inequality to numerical integration and special means.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.347-354
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• 2008

We introduce a series of studies on turbulent skin friction drag reduction in wall-turbulence. First, an identity equation relating the skin friction drag and the Reynolds shear stress (the FIK identity) is introduced. Based on the implication of the FIK identity, a new analytical suboptimal feedback control law requiring the streamwise wall-shear stress only is introduced and direct numerical simulation (DNS) results of turbulent pipe flow with that control is reported. We also introduce DNS of an anisotropic compliant surface and parameter optimization using an evolutionary optimization technique.

• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.347-354
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• 2008

We introduce a series of studies on turbulent skin friction drag reduction in wall-turbulence. First, an identity equation relating the skin friction drag and the Reynolds shear stress (the FIK identity) is introduced. Based on the implication of the FIK identity, a new analytical suboptimal feedback control law requiring the streamwise wall-shear stress only is introduced and direct numerical simulation (DNS) results of turbulent pipe flow with that control is reported. We also introduce DNS of an anisotropic compliant surface and parameter optimization using an evolutionary optimization technique.