• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.1
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• pp.20-28
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• 2014

This paper presents static output feedback LQ and $H_{\infty}$ controllers for rollover prevention. Linear quadratic static output feedback controllers have been proposed for rollover prevention in such a way to minimize the lateral acceleration and the roll angle. Rollover prevention capability can be enhanced if $H_{\infty}$ controller is designed. To avoid full-state measurement for feedback requirement or sensitiveness of an observer to nonlinear model error, static output feedback is adopted. To design static output feedback controllers, Kosut's method is adopted because it is simple to calculate. Differential braking and active anti-roll bar are adopted as actuators that generate yaw and roll moments, respectively. The proposed method is shown to be effective in preventing rollover through the simulations on nonlinear multi-body dynamic simulation software, CarSim.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.11
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• pp.7-14
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• 2005

A subdomain-interface finite element method is suggested to solve a class of fully- coupled thermomechanical problems with contact boundaries. The penalty method is used for connecting subdomains that satisfy interface compatibility conditions. As a result, effective stiffness matrices are always positive definite, and computational efficiency can be improved to a considerable degree. Moreover, any complex-shaped domain can be divided into independently modeled subdomains without considering the conformity of meshes on interfaces. Using a computer code based on the present method, these advantageous features are shown through a set of numerical studies.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.5
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• pp.1108-1113
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• 2004

‘Set’ is a tool that is used frequently in designing computer programs. Because of the reason, ‘set constraints languages’ have been developed recently. In this research, we introduce ‘(Ab)(Cl) set unification’ problem and implement it using the ‘set equation rewriting in Prolog’. In this research we shows that the set unification, that is considered to be difficult to be implemented in procedural languages, ran be implemented easily using the non-deterministic control structure and the list data structure in logic language like Prolog. Our research uses the Ciao Prolog with GNU GPL, this is compared with other existing implementations which used expensive commercial Prolog, so anyone can use the result freely. Currently the result is being used for implementing a set constraint language.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.5
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• pp.404-411
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• 2007

new domain/boundary decomposition method is suggested to perform efficient finite element analyses of contact problems. A penalty method is used for connecting an interface or contact interfaces with neighboring subdomains that satisfy continuity conditions. As a result, the derived effective stiffness matrices are always positive definite, and computational efficiency can be improved to a considerable degree. Moreover, any complex-shaped domain can be divided into independently modeled subdomains without considering the conformity of meshes along the interface. Using a computer code based on the present method, these advantageous features are confirmed through a set of numerical examples.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.4
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• pp.251-263
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• 2003

This paper presents matrix inequality conditions for Η$_2$control and Η$_2$controller design method of linear time-invariant descriptor systems with parameter uncertainties in continuous and discrete time cases, respectively. First, the necessary and sufficient condition for Η$_2$control and Η$_2$ controller design method are expressed in terms of LMI(linear matrix inequality) with no equality constraints in continuous time case. Next, the sufficient condition for Hi control and Η$_2$controller design method are proposed by matrix inequality approach in discrete time case. Based on these conditions, we develop the robust Η$_2$controller design method for parameter uncertain descriptor systems and give a numerical example in each case.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.1
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• pp.33-41
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• 2002

In this paper, we present a frequency weighted model reduction using LMIs for minimizing the H$\infty$ weighted model error compared with the methods of frequency weighted balanced truncation and frequency weighted Hankel norm approximation. The proposed algorithm, its form is equal to the sufficient condition of performance preserving controller approximation, is based on an iterative two-step LMI scheme induced from bound real lemma. So, it can be applied to the problem of the performance preserving controller approximation. The controller reduction is useful in a practical control design and ensures its easy implementation and high reliability The validity of the proposed algorithm is shown through numerical examples. Additionaly, we extend the proposed algorithm to performance preserving controller approximation by applying to the HIMAT(highly maneuverable aircraft technology) system.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.5
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• pp.22-28
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• 2009

In this paper, we consider the problem of $H_{\infty}$ filtering for continuous-time singular systems with multiple state-delays. The aim of designed filter is to guarantee regularity, impulse-free, asymptotic stability and $H_{\infty}$ norm bound of filtering error singular system. By establishing a finite sum inequality based on quadratic terms, a new delay-dependent BRL (bounded real lemma) for singular systems with multiple state-delays is derived. Based on the result, the existence condition of $H_{\infty}$ filter and filter design method are proposed in terms of LMI (linear matrix inequality). Finally, a numerical example is provided to show the validity of the design methods.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.3 s.357
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• pp.1-5
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• 2007

SiOC films were made using the oxygen and bistrimethylsilylmethane mixed precursor. The chemical properties of SiOC films divided into three properties, organic, hybrid and inorganic depending on the flow rate ratio between oxygen and bistrimethylsilylmethane precursor. The films with organic properties decreased dielectric constant, because of pore incorporation in final materials. In this study, the porosity of SiOC films with organic properties was investigated using the Makwell-Garnett equation. The porosity of the films could be correlated with the blue shift in the infrared spectra scopy, and increased with the decreasing the dielectric constant of the film.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.5
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• pp.571-576
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• 2004

This paper presents a delay dependent fuzzy $H_{\infty}$ controller design method for delayed fuzzy dynamic systems. Using delay-dependent Lyapunov function, the global exponential stability and $H_{\infty}$ performance problem arc discussed. A sufficient conditions for the existence of fuzzy controller is presented in terms of linear matrix inequalities(LMIs). A simulation example is given to illustrate the design procedures and performances of the proposed methods.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.1
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• pp.94-99
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• 2012

This paper discusses a decentralized sampled-data control problem for large-scale nonlinear systems. The system is represented in Takagi-Sugeno's form. Next, we design a decentralized analog controller based on the overlapping decomposition technique. The final step is to apply the intelligent digital redesign scheme for converting the analog controller into the sampled-data one. Design condition is represented in terms of linear matrix inequalities. A simulation result is provided for the effectiveness of the proposed design method.