• Structural Engineering and Mechanics
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• v.39 no.6
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• pp.751-765
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• 2011

The present paper deals with the identification of a concentrated damage in an elastic parabolic arch through the minimization of an objective function which measures the differences between numerical and experimental values of static displacements. The damage consists in a notch that reduces the height of the cross section at a given abscissa and therefore causes a variation in the flexural stiffness of the structure. The analytical values of static displacements due to applied loads are calculated by means of the principle of virtual work for both the undamaged and damaged arch. First, pseudo-experimental data are used to study the inverse problem and investigate whether a unique solution can occur or not. Various damage intensities are considered to assess the reliability of the identification procedure. Then, the identification procedure is applied to an experimental case, where displacements are measured on a prototype arch. The identified values of damage parameters, i.e., location and intensity, are compared to those obtained by means of a dynamic identification technique performed on the same structure.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.845-848
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• 2003

There are many researches on using human neuro-biological signals for various problems such as controlling a mechanical object and/or interfacing human with the computer. It is one of very interesting topics that human can use various instruments without learning specific knowledge if the instruments can be controlled as human intends. In this paper, we proposed an intelligent motion planner for a redundant manipulator, which is controlled by humans neuro-biological signals, especially, EOG (Electrooculogram). We found the optimal motion planner for the redundant manipulator that can move to the desired point. We used neural networks to find the inverse kinematics solution of the manipulator. We also showed the performance of the proposed motion planner with several simulations.

• Journal of the Korea Computer Graphics Society
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• v.2 no.2
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• pp.53-60
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• 1996

In 3D graphics interface, 3D objects and virtual camera have many degrees of freedom. We interpret the control of 3D objects and virtual camera as a problem of kinematics and inverse kinematics. It is well known that extra degrees of freedom introduce various singularities in inverse kinematics. In this paper, we approach 3D graphics interface problems by reducing redundant degrees of freedom so that the control degrees of freedom matches with the degrees of freedom in the motions of 3D objects and virtual camera.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.154-156
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• 1996

A new method for electric resistivity tomography(ERT) is developed for geophysical inverse problems by adapting the sensitivity analysis. The outputs of the potential electrodes are computed using two dimensional finite element method in the wave number space by Fourier transforming the governing equations. The resistance distribution in the region of interests, which makes the computed potential distribution coincide with the measured potential, is found by minimizing the objective function using an optimization method. In this process the sensitivity analysis is introduced in order to compute the derivatives of the objective function. And an adjoint variable method is used to save the computational efforts for sensitivity coefficients.

• The Korean Journal of Applied Statistics
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• v.20 no.2
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• pp.373-385
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• 2007

The solution of the normal equation arising in a general linear model by the least square methods is not unique in general. Conventionally, SAS IML and G-inverse matrices are considered for such problems. In this paper, we provide a systematic solution procedures for SAS IML.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.550-553
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• 2005

To acquire radar target signature, various kinds of target are necessary. Measurement is one of the data acquiring method, but much time and high cost is required to get the target data from the real targets. Even if we can afford that, the targets we can access are very limited. To obtain target signatures avoiding these problems, we build the target CAD (Computer Aided Design) model for the calculation of target signatures. To speed up RCS calculation, we applied adaptive super-sampling and tested quite complex tank CAD model which is 1.4 hundred of thousands facet. We use calculated RCS data for ID range profile and 2D ISAR (Inverse Synthetic Aperture Radar) image formation. We adopted IFFT (Inverse Fast Fourier Transform) algorithm combined with polar formatting algorithm for the ISAR imaging. We could confirm the possibility of the construction of database from the images of CAD models for target classification applications.

• Journal of applied mathematics & informatics
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• v.28 no.1_2
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• pp.351-361
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• 2010

The solution of large sparse linear systems is one of the most important problems in large scale scientific computing. Among the many methods developed, the preconditioned Krylov subspace methods are considered the preferred methods. Selecting a suitable preconditioner with appropriate parameters for a specific sparse linear system presents a challenging task for many application scientists and engineers who have little knowledge of preconditioned iterative methods. The prediction of ILU type preconditioners was considered in [27] where support vector machine(SVM), as a data mining technique, is used to classify large sparse linear systems and predict best preconditioners. In this paper, we apply the data mining approach to the sparse approximate inverse(SAI) type preconditioners to find some parameters with which the preconditioned Krylov subspace method on the linear systems shows best performance.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.362-365
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• 2007

In wind turbine blades, airfoils are required to have different spec when compared with airplane airfoil. Airfoils for wind turbine blade must have a high lift-to-drag ratio, moderate to high lift and especially low roughness sensitivity. Also an operation Re. No.s are lower than conventional airplane airfoils. At mid-span and inboard region, structural problems have to be considered. Especially, for stall regulated type, moderate stall behavior is essential part of design. For these reasons, airfoil design for HAWT blade is essential part of blade design. In this paper, root airfoil and tip airfoil are discussed. For a root region, 24% thickness airfoil is designed and for a top region, 12% thickness ratio is done. A inverse design method and panel method are used for rapid airfoil design. In this paper, a design method, features of airfoil shape and characteristics are discussed.

• Journal of KSNVE
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• v.6 no.5
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• pp.653-660
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• 1996

There have been many studies to control holonomic and/or nonholonomic systems, and nonlinear control problems. However, their approaches require complicated intermediate procedures. Using the Generalized Inverse Method derived by Udwadia and Kalaba in 1992, this study provides two applications to the control of holonomically and/or nonholonomically constrained systems. These applications illustrate the ease with which the equation by the Generalized Inverse Method can be utilized for the purpose of (a) control of highly nonlinear systems without depending on any linearization, (b) maintaining precision tracking motions with the presence of known disturbances, and (c) explicit determination of control forces under the circumstances (a) and (b).

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.220-222
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• 2006

This paper presents intelligent digital redesign method of global approach for hybrid state space fuzzy-model-based controllers. For effectiveness and stabilization of continuous-time uncertain nonlinear systems under discrete-time controller, Takagi-Sugeno(TS) fuzzy model is used to represent the complex system. And global approach design problems viewed as a convex optimization problem that we minimize the error of the norm bounds between nonlinearly interpolated lineal operators to be matched. Also, by using the bilinear and inverse bilinear approximation method, we analyzed nonlinear system's uncertain parts more precisely. When a sampling period is sufficiently small, the conversion of a continuous-time structured uncertain nonlinear system to an equivalent discrete-time system have proper reason. Sufficiently conditions for the global state-matching of the digitally controlled system are formulated in terms of linear matrix inequalities (LMIs). Finally, a T-S fuzzy model for the chaotic Lorentz system is used as an example to guarantee the stability and effectiveness of the proposed method.