• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.1 s.256
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• pp.89-96
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• 2007

A volume integral equation method (VIEM) is applied for the effective analysis of plane elastostatic problems in unbounded solids containing single isotropic inclusion of two different shapes considering composite fiber volume fraction. Single cylindrical inclusion and single square cylindrical inclusion are considered in the composites with six different fiber volume fractions (0.25, 0.30, 0.35, 0.40, 0.45, 0.50). Using the rule of mixtures, the effective material properties are calculated according to the corresponding composite fiber volume fraction. The analysis of plane elastostatic problems in the unbounded effective material containing single fiber that covers an area corresponding to the composite fiber volume fraction in the bounded matrix material are carried out. Thus, single fiber, matrix material with a finite region, and the unbounded effective material are used in the VIEM models for the plane elastostatic analysis. A detailed analysis of stress field at the interface between the matrix and the inclusion is carried out for single cylindrical or square cylindrical inclusion. Next, the stress field is compared to that at the interface between the matrix and the single inclusion in unbounded isotropic matrix with single isotropic cylindrical or square cylindrical inclusion. This new method can also be applied to general two-dimensional elastodynamic and elastostatic problems with arbitrary shapes and number of inclusions. Through the analysis of plane elastostatic problems, it will be established that this new method is very accurate and effective for solving plane elastic problems in unbounded solids containing inclusions considering composite fiber volume fraction.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.7
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• pp.401-403
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• 2014

In this paper, we address data detection technique using Fixed complexity LLL-based signal detection over multi-antenna SC-FDMA wireless channels. We use the property of effective channel matrix of SC-FDMA system. We can make the large effective channel matrix to various small effective channel matrix. We show that error performance of proposed detection technique.

• ETRI Journal
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• v.20 no.4
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• pp.361-379
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• 1998

We present an improved transfer matrix algorithm which can be used in solving general n-band effective-mass $Schr{\ddot{o}}dinger$ equation for quantum well structures with arbitrary shaped potential profiles(where n specifies the number of bands explicitly included in the effective-mass equation). In the proposed algorithm, specific formulas are presented for the three-band (the conduction band and the two heavy- and light-hole bands) and two-band (the heavy- and light-hole bands) effective-mass eigensystems. Advantages of the present method can be taken in its simple and unified treatment for general $n{\times}n$ matrix envelope-function equations, which requires relatively smaller computation efforts as compared with existing methods of similar kind. As an illustration of application of the method, numerical computations are performed for a single GaAs/AlGaAs quantum well using both the two-band and three-band formulas. The results are compared with those obtained by the conventional variational procedure to assess the validity of the method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.6 s.165
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• pp.968-978
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• 1999

The effective elastic properties of materials containing spherical inclusions were calculated by the elastic wave scattering theory. In the formulation additional scattering fields by the presence of random multiple scatterers that affects the effective properties were found by the single scattering approximation. In calculating the scattering fields the ensemble average on the displacements and strains inside the scatterer was found from the static approximation at long wavelength limit. The displacements were assumed to be equal to the incident field, while the strains were calculated by Eshelby's equivalent inclusion principle on the single inclusion problem. Four different models were considered and they reflected different degrees of multiple scattering effects based on the approximation introduced in the process of embedding the inclusion in the matrix. The expressions for the effective elastic constants were given in each model, and their relations to the results obtained from other scattering theory and elasticity theory were discussed. The theoretical predictions were compared with experimental results on the epoxy matrix composites containing tungsten particles of different sizes and volume fractions

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2004-2009
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• 2003

A robust optimal control design is proposed in this study for rigid robotic systems under the unknown load and the other uncertainties. The uncertainties are quadratically bounded for some positive definite matrix. Iterative method finding the Q weighting matrix is shown. Computer simulations have been done for a weight-lifting operation of a two-link manipulator and the result of the simulation shows that the proposed algorithm is very effective for a robust control of robotic systems.

• Analytical Science and Technology
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• v.20 no.2
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• pp.176-182
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• 2007

The present study relates to a matrix-typed, sustained-releasing agent comprising agrochemical effective ingredients being capable of recognizing a content of moisture, and a preparation method thereof. The curdlan solution added to acid was formed matrix which has unique network structure. The matrix treated by heat lost water solubility. The network structure of matrix was opened in the aquatic condition but closed again in dry condition. Therefore, in the sustained-releasing formulation system, an agrochemical effective ingredient was released from the formulation only in the aquatic condition. Use of the composition according to the product can control a manifesting time of effects of agrochemicals and can provide agrochemicals with reduced harmful damages.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.12
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• pp.435-440
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• 1983

The methods of forming the bus impedance matrix, which is mainly employed in fault analysis of power system, can be generally classified in catagories, (1) the one being the inverse matrix of bus admittance matrix, and (2) the other the bus impedance matrix succesive formation method by particular algorithms. The former method is theouetically elegant, but the formation and inverse of complex bus admittance matrix for large power system requires too much amounts of computer memory space and computing time. The latter method also requires too much memory space. Therefore, in this paper, an algorithm and computer program is introduced for the formation of a sparse bus impedance matrix which generates only the matching terms of the admittance matrix. So, this method can reduce the computer memory and computing time, and can be applied to fault analysis of large power system by small digital computer.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.220-223
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• 2003

The methodology of micromechanical finite element method (MFEM) is proposed to calculate the micromechanical strains on fiber and matrix under mechanical and thermal loadings. For micromechanical analysis, composite structure is idealized the square and hexagonal unit cells. Boundary conditions are determined to calculate the effective material properties of composites and the strain magnification matrix. And they are verified by comparing with the results from multi cells, and the strain distributions of the unit cells are in accordance with those of the multi cells. Finally, the effective material properties of composite structure are obtained with respect to its fiber volume fraction and compared with results from rules-of-mixture.

• Journal of Power Electronics
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• v.15 no.3
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• pp.702-711
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• 2015

In this paper, an effective carrier-based modulation (CBM) strategy to reduce the switching losses for indirect matrix converters (IMCs) is presented. The discontinuous pulse width modulation method is applied to decrease the switching numbers in one carrier cycle, and an optimum offset voltage is selected to avoid commutations of the high output phase currents. By decreasing the switching numbers along with avoiding commutation of the high currents, the proposed CBM strategy significantly reduces the switching losses in IMCs. In addition, the proposed CBM strategy is independent of load conditions, such as load power and power factor, and it has good performance in terms of the input/output waveforms. Simulation and experimental results are provided to verify the effectiveness of the proposed CBM strategy.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.8
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• pp.766-770
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• 2010

In this paper, we present an effective covariance tracking algorithm based on adaptive size changing of tracking window. Recent researches have advocated the use of a covariance matrix of object image features for tracking objects instead of the conventional histogram object models used in popular algorithms. But, according to the general covariance tracking algorithm, it can not deal with the scale changes of the moving objects. The scale of the moving object often changes in various tracking environment and the tracking window(or object kernel) has to be adapted accordingly. In addition, the covariance matrix of moving objects should be adaptively updated considering of the tracking window size. We provide a solution to this problem by segmenting the moving object from the background pixels of the tracking window. Therefore, we can improve the tracking performance of the covariance tracking method. Our several simulations prove the effectiveness of the proposed method.