• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1998년도 제13차 학술회의논문집
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• pp.289-294
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• 1998

The distributed-parameter structures expressed with the partial differential equations are considered as the infinite-dimensional dynamic system. For implementation of a controller in multivariate systems, it is necessary to derive the state-space reduced order model. By the eigensystem realization algorithm, we can yield tile subspace system with the Markov parameters derived from the measured frequency response function by the inverse discrete Fourier transformation. We also review the necessary conditions for the convergence of the approximation system and the error bounds in terms of the singular values of Markov-parameter matrices. To determine the natural frequencies and modal damping ratios, the modal coordinate transformation is applied to the realization system. The vibration test for a smart structure is performed to provide the records of frequency response functions used in the subspace system realization.

• Archives of Pharmacal Research
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• 제28권6호
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• pp.730-735
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• 2005

Nine polymorphic modifications of doxazosin mesylate have been obtained by recrystallization in organic solvents under variable conditions. Different polymorphs of doxazosin mesylate were characterized by powder X-ray crystallography diffractometry (PXRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TG). Transformation of Form 1 and Form 2 was not occurred in three relative humidities ($0\%$, $51\%$, and $99\%$) at 20$\pm$0.5 for 30 days.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.52.2-52
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• 2002

In this paper we consider an approach to a formal linearization for time-variant nonlinear systems. A time-variant nonlinear sysetm is assumed to be described by a time-variant nonlinear differential equation. For this system, we introduce a coordinate transformation function which is composed of the Chebyshev polynomials. Using Chebyshev expansion to the state variable and Laguerre expansion to the time variable, the time-variant nonlinear sysetm is transformed into the time-variant linear one with respect to the above transformation function. As an application, we synthesize a time-variant nonlinear observer. Numerical experiments are included to demonstrate the validity of...

• Journal of Pharmaceutical Investigation
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• 제37권1호
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• pp.23-26
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• 2007

Two crystal forms of cefuroxime axetil were obtained by the recrystallization from different organic solvents and characterized by differential scanning calorimetry (DSC), X-ray powder diffraction (XRD). It was confirmed that two crystal forms are identical. The dissolution patterns of these two forms were also checked in 0.07 N HCl at $37{\pm}0.5^{\circ}C$, 100 rpm for 180 minutes. The transformation during storage was also studied.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2082-2084
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• 2003

A practical real-time LOS rate estimator is proposed to handle the time-varying measurement noise statistics. To calculate the optimal Kalman gain, the algebraic transformation method is taken into account. By using the algebraic transformation, the differential algebraic Riccati equation(DARE) regarding estimation error covariance is replaced by the simple algebraic Riccati equation(ARE). The proposed LOS estimation filter gain is only a function of relative range. Consequently, the proposed method is computationally very efficient and suitable for embedded environment.

• Journal of applied mathematics & informatics
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• 제22권1_2호
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• pp.223-235
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• 2006

By applying the Landau-type transformation, we transform a Stefan problem with nonlinear free boundary condition into a system consisting of a parabolic equation and the ordinary differential equations. Fully discrete finite element method is developed to approximate the solution of a system of a parabolic equation and the ordinary differential equations. We derive optimal orders of convergence of fully discrete approximations in $L_2,\;H^1$ and $H^2$ normed spaces.

• Structural Engineering and Mechanics
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• 제48권5호
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• pp.697-709
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• 2013

A simulation method called modified differential transform is studied to solve the free vibration problems of uniform Euler-Bernoulli beam. First of all, the modified differential transform method is derived. Secondly, the modified differential transformation is applied to uniform Euler-Bernoulli beam free-free vibration. And then a set of differential equations are established. Through algebraic operations on these equations, we can get any natural frequency and normalized mode shape. Thirdly, the FEM is applied to obtain the numerical solutions. Finally, mode experimental method (MEM) is conducted to obtain experimental data for analysis by signal processing with LMS Test.lab Vibration testing and analysis system. Experimental data and simulation results are illustrated to be in comparison with the analytical solutions. The results show that the modified differential transform method can achieve good results in predicting the solution of such problems.

• 전력전자학회논문지
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• 제8권2호
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• pp.107-115
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• 2003

PMSM은 높은 토크 특성과 우수한 전력 밀도, 논은 효율 때문에 산업용 빛 가정용 기기로 널리 사용되고 있다. PMSM의 우수한 제어 수행을 위해서는 회전자 위치의 정확한 정보가 필요하다. 그러나 위치 센서의 가격이 비싸고, 열악한 환경에서 신뢰도가 떨어지기 때문에 최근에는 센서리스 알고리즘에 대한 연구가 많이 진행되고 있다. 본 논문에서는 회전자 위치의 추정을 위해 쇄교 자속의 도함수를 이용한다. 수치적 미분을 행하지 않고 전압 방정식과 측정된 상전류를 이용한 수식적 미분을 통해 쇄교 자속을 구하는 a-$\beta$ 변환과 수식적 미분을 이용한 새로운 센서리스 알고리즘을 제안한다. 제안된 센서리스 속도 제어 알고리즘이 실험을 통해 증명된다.

• 전력전자학회논문지
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• 제27권1호
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• pp.63-73
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• 2022

The differential power processor (DPP) system is used to prevent a decrease in the total power generation due to the partial shading of photovoltaic modules. Compared with traditional series strings and full power processing (FPP) converter solutions, the DPP converter system shows advantages in terms of modularization process, volume, and transformation losses. However, the system has a limitation in that the power generation process of differential power processors produces lower power under certain irradiation conditions. This paper proposes a structure and operating algorithm for differential power processing modules that can use a single power converter for multiple strings. The operational algorithm for the differential power regulators allows the maximum power generation to be maintained in comparison with conventional series-connected and differential power processing methods even under various partial shading conditions. The operation algorithm of the proposed DPP is verified by Matlab/Simulink simulations.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제8권1호
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• pp.19-30
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• 2004

This research applies the discursive approach to investigate the social transformation of students' conceptual model of differential equations. The analysis focuses on the students' use of metaphor in class in order to find kinds of metaphor used, their characteristics, and a pattern in the use of metaphor. Based on the analysis, it is concluded that the students' conceptual model of differential equations gradually becomes transformed with respect to the historical and cultural structure of the communal practice of mathematics. The findings suggest that through participating in the daily practice of mathematics as a historical and cultural product, a learner becomes socially transformed to a certain kind of a cultural being with historicity. This implies that mathematics education is concerned with the formation of historical and cultural identity at a fundamental level.