• Proceedings of the KIEE Conference
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• 1979.08a
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• pp.80-82
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• 1979

While the standard linear-quadratic-Gaussian problem has fixed horizons, this paper considers the LQG problem with moving horizons. By the separation principle the solution will be given by the kalman filter with the approaching horizon and the LQ regulator with the receding horizon. Sufficient conditions on weighting matrices are derived under which the filter and regulator are asymptotically stable. It wall be shown that the computation method of the moving-horizon LQG regulators is better than that of the standard LQG regulator. The performance measure between the two optimal controls will be compared. A simulation result is given in order to show the usefulness of the moving-horizon LQG regulator.s

• International Journal of Automotive Technology
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• v.7 no.7
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• pp.795-801
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• 2006

A No Spin Differential (NSD) design has been improved from evaluation of two NSD models utilizing the axiomatic approach. New design parameters of the second level are developed to satisfy the independence axiom. The design matrices are determined to decouple the relationship between design parameters and process parameters. The values of process parameters are then determined to optimize and improve the NSD design. Consequently a unique and evolutionary NSD design is achieved with the aid of the axiomatic approach.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.379-384
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• 2002

The deterioration of concrete due to sulfate ions in various sulfate environments such as groundwater, soil and seawater is one of important factors degrading the durability of concrete structure. The aim of this paper is to evaluate on the magnesium sulfate alttack resistance of mortars with silica fume. In this study, compressive strength loss and length change of prismatic mortars, containing silica fume, immersed in 5% magnesium sulfate solution for 270 days were investigated. Additionally, paste powders with same binder were used to observe reactants of cement matrices through the instrumental analysis such as XRD, SEM and MIP. Results obtained from this study indicate that the greater damaging effects of the magnesium soulution are due to the decomposition of the C-S-H gel to M-C-S-H.

• Journal of the Korean Mathematical Society
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• v.45 no.3
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• pp.771-780
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• 2008

Let $M_C=\(\array{A&C\\0&B}\)$ be a $2{\times}2$ upper triangular operator matrix acting on the Hilbert space $H{\bigoplus}K\;and\;let\;{\sigma}_w(\cdot)$ denote the Weyl spectrum. We give the necessary and sufficient conditions for operators A and B which ${\sigma}_w\(\array{A&C\\0&B}\)={\sigma}_w\(\array{A&C\\0&B}\)\;or\;{\sigma}_w\(\array{A&C\\0&B}\)={\sigma}_w(A){\cup}{\sigma}_w(B)$ holds for every $C{\in}B(K,\;H)$. We also study the Weyl's theorem for operator matrices.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.568-569
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• 2003

Functional cosmetic ingredients such as L-ascorbic acid, retinoic acid, indole-3-acetic acid, salicylic acid, acidic dye(indigo carmine) are intercalatively encapsulated by skin-friendly metal hydroxides and oxides matrices. Such functional organic-inorganic nanohybrids are realized via chemical coprecipitation and surface coating reactions. The hetero-structural nature of these nanohybrids, their particle morphology and textural characterizations are mainly discussed on the basis of powder X-ray diffraction, electron microscopies, and high performance liquid chromatographic analyses. The cosmetic ingredients encapsulated in inorganics show greatly improved storage stability, sustained releasing property as well as higher transdermal transfer efficiency.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.10a
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• pp.168-175
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• 1996

This paper deals with the variable-node element for fluid flow and the adaptive h-version mesh refinement algorithm. The transient element has been formulated by the Galerkin approach in which the pressure term is replaced with the penalty function. The present element having variable mid-side node and is suitable for constructing a locally refined mesh avoiding the use of the highly distorted elements. A modified Gauss quadrature is needed to integrate the element matrices to solve the trouble associated with the discontinuity of derivatives of shape functions. Several numerical examples show that the proposed element can be effectively used in the h-version adapt ive mesh refinement

• Structural Engineering and Mechanics
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• v.11 no.4
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• pp.443-460
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• 2001

This paper presents an effective application of a variable-node axisymmetric solid element designated as AQV (Axisymmetric Quadrilateral Variable-node element). The variable-node element with physical midside nodes helps to overcome some problems in connecting the different layer patterns on a quadrilateral mesh in the adaptive h-refinement. This element alleviates the necessity of imposing displacement constraints on irregular (hanging) nodes in order to enforce the inter-element compatibility. Therefore, the elements with variable mid-side nodes can be used effectively in the local mesh refinement for the axisymmetric structures which have stress concentrations. A modified Gaussian quadrature should be adopted to evaluate the stiffness matrices of the variable-node elements mainly because of the slope discontinuity of assumed displacement within the elements. Some numerical examples show the usefulness of variable-node axisymmetric elements in the practical application.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.221-223
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• 1993

The Hopfield model is defined as an adaptive dynamic system. In this paper we propose a modified neural network which is capable of solving linear programming problems and a set of linear equations. The model is directly implemented from the given system, and solves the problem without calculating the inverse of the matrices. We get the better stability results by the addition of scaling property and by using the nonlinearities in the linear programming neural networks.

• Proceedings of the KSEEG Conference
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• 2004.12a
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• pp.9-28
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• 2004

Concern about arsenic is increasing throughout the world, including areas of the United States. Elevated levels of arsenic above current drinking-water regulations in ground and surface water can be the result of purely natural phenomena, but often are due to anthropogenic activities, such as mining and agriculture. The current study correlates arsenic speciation in acid mine drainage and mining influenced water with the important water-chemistry properties Eh, pH, and iron(III) concentration. The results show that arsenic speciation is generally in equilibrium with iron chemistry in low pH AMD, which is often not the case in other natural-water matrices. High pH mine waters and groundwater do not 짐ways hold to the redox predictions as well as low pH AMD samples. The oxidation and precipitation of oxyhydroxides depletes iron from some systems, and this also affects arsenite and arsenate concentrations differently through sorption processes.

• International Journal of Control, Automation, and Systems
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• v.4 no.3
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• pp.271-280
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• 2006

This paper proposes a new approach to solve robust $H{\infty}$ control problems for uncertain continuous-time descriptor systems. Necessary and sufficient conditions for robust $H{\infty}$ control analysis and design are derived and expressed in terms of a set of LMIs. In the proposed approach, the uncertainties are allowed to appear in all system matrices. Furthermore, a couple of assumptions that are required in earlier design methods are not needed anymore in the present one. The derived conditions also include several interesting results existing in the literature as special cases.