• Journal of Power Electronics
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• 제10권1호
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• pp.43-50
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• 2010

This paper proposes a new harmonic elimination PWM (HEPWM) scheme for voltage source inverters (VSI) based on the curve fittings of certain polynomials functions. The resulting equations to calculate the switching angle of the HEPWM require only the addition and multiplication processes; therefore any number of harmonics to be eliminated and the fundamental amplitude of the pole switching waveform (NP1) can be controlled on-line. An extensive angle error analysis is carried out to determine the accuracy of the algorithm in comparison to the exact solution. To verify the workability of the technique, an experimental single phase VSI is constructed. The algorithm is implemented on a VSI using a 16-bit microprocessor. The results obtained from the test rig are compared to the theoretical prediction and the results of the MATLAB simulations.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권3호
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• pp.125-132
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• 2002

This paper presents a single-phase 3-level PWM inverter to alleviate the harmonic components of output voltage and current under the conditions of identical supply DC voltage and switching frequency to the conventional inverter. Operational principles and analysis are performed, and the switching functions are derived. Deadbeat controller is also designed and implemented for the inverter to keep the output voltage being sinusoidal and to have the high dynamic performances even in the cases of load variations and the partial magnetization of filter inductor. The validity of proposed inverter is proved from the simulated and experimented results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.37-39
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• 2005

This paper is proposed maximum thrust design of slotted Permanent Magnet Linear Synchrous Motor (PMLSM) using surface harmonic method considering slot effect. The genetic algorithm is used for optimization. The objective functions are the maximum thrust and the minimum detent force. This time, design parameters are set as PM width, PM height and slot width.

• Journal of electromagnetic engineering and science
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• 제8권1호
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• pp.6-11
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• 2008

Advances in low power design open the possibility to harvest energy from the environment to power electronic circuits. Electrical energy can be harvested from piezoelectric transducer. Piezoelectric materials can be used as mechanisms to transfer mechanical energy usually vibrating system into electrical energy that can be stored and used to power other devices. Micro- to milli-watts power can be generated from vibrating system. We developed definitive and analytical models to predict the power generated from a cantilever beam attached with piezoelectric transducer. Analytical models are pin-force method, enhanced pin-force method and Euler-Bernoulli method. Harmonic oscillations and random noise will be the two different forcing functions used to drive each system. It has been selected the best model for generating electric power based upon the analytical results obtained.

• Structural Engineering and Mechanics
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• 제18권2호
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• pp.195-209
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• 2004

By means of the two-dimensional basic equations of transversely isotropic magneto-electro-elastic media and the strict differential operator theorem, the general solution in the case of distinct eigenvalues is derived, in which all mechanical, electric and magnetic quantities are expressed in four harmonic displacement functions. Based on this general solution in the case of distinct eigenvalues, a series of problems is solved by the trial-and-error method, including magneto-electro-elastic rectangular beam under uniform tension, electric displacement and magnetic induction, pure shearing and pure bending, cantilever beam with point force, point charge or point current at free end, and cantilever beam subjected to uniformly distributed loads. Analytical solutions to various problems are obtained.

• Wind and Structures
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• 제28권6호
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• pp.347-354
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• 2019

This study provides an approximate analytical solution to the fractional vibration problem of thin plate governing anomalous motion of plate subjected to in-plane loads. The method of variable separable is employed to transform the fractional partial differential equations under consideration into a fractional ordinary differential equation in temporal variable and a bi-harmonic plate equation in spatial variable. The technique of conformable fractional derivative is utilized to solve the resulting fractional differential equation and the approach of finite sine integral transform method is used to solve the accompanying bi-harmonic plate equation. The deflection field which measures the transverse displacement of the plate is expressed in terms of product of Bessel and trigonometric functions via the temporal and spatial variables respectively. The obtained solution reduces to the solution of the free vibration problem of thin plate in literature. This work shows that conformable fractional derivative is an efficient mathematical tool for tracking analytical solution of fractional partial differential equation governing anomalous vibration of thin plates.

• 호남수학학술지
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• 제46권3호
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• pp.365-377
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• 2024

In this paper, we give some sums involving the generalized harmonic numbers H^r_n (σ) and the (q, r)-binomial coefficient $\left({L \atop k}\right)_{q,r}$ by using Euler's transform. For example, for (c, r) ∈ ℤ⁺ × ℝ⁺, $${\sum_{n=0}^{\infty}}{\sum_{k=0}^{n}}\,(-1)^k\,\left({n+r \atop n-k}\right)\frac{c^{n+1}H^{r-1}_k({\sigma})}{(n+1)(1+c)^{n+1}}=-(c+{\frac{1}{{\sigma}}})\,{\ln}\,(1+c{\sigma})+c,$$ and $${\sum_{k=0}^{n}}\left({n \atop k}\right)\left({L \atop k}\right)_{2,r}={\sum_{j=0}^{n}}{\sum_{k=0}^{j}}(-1)^k\left({j-k+2L+r \atop j-k}\right)\left({r \atop n-j}\right)\left({L \atop k}\right)_2,$$ where σ is appropriate parameter, H^r_n (σ) is the generalized hyperharmonic number of order r and $\left({L \atop k}\right)_q$ is the q-binomial coefficient.

• 대한수학회보
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• 제61권4호
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• pp.1033-1051
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• 2024

In this paper, we define a parametric variant of generalized Euler sums and construct contour integration to give some explicit evaluations of these parametric Euler sums. In particular, we establish several explicit formulas of (Hurwitz) zeta functions, linear and quadratic parametric Euler sums. Furthermore, we also give an explicit evaluation of alternating double zeta values ${\zeta}({\bar{2j}};\,2m+1)$ in terms of a combination of alternating Riemann zeta values by using the parametric Euler sums.

• 자원환경지질
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• 제49권4호
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• pp.269-280
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• 2016

지역에 최적화된 스레피안 구면함수(spherical Slepian function)를 활용하여 남극을 중심으로 반경 $20^{\circ}$ 범위의 지역에 지각 자기이상의 3개의 방향 성분과 6개의 구배성분들을 표현하였다. 2013년 11월 유럽 항공 우주국이 발사한 3개의 자력 위성인 Swarm은 궤도 전개를 통해 동서 방향의 구배값은 물론 남북 및 수직방향의 구배값을 얻을 수 있도록 계획하였다. 이미 발사된 여러 중력위성들(i.e., GRACE and GOCE) 역시 이러한 구배값을 활용하여 보다 정확한 중력 이상값 및 지표에서의 시간에 따른 중력변화 연구등을 수행해 왔으나 자력 위성자료를 통해서는 많은 연구들이 이루어지고 있지 않는 상태이다. 한편 지역화 모델링은 관심 지역 또는 자료 분포의 제한인 지역인 경우에 활용될 수 있다. 또한 전지구 모델보다 효율적인 연산이 가능하여 위성자료로부터 고해상도의 지각 자기이상값을 표현할 수 있다는 장점을 지니고 있다. 또한 기존의 전지구 구면조화함수의 선형 결합으로 이루어진 기저함수들은 서로 직교성(orthogonality)이 유지되므로 스레피안 구면함수의 계수를 전지구 구면조화함수의 계수로 변환이 가능하여 스펙트럼 분석에 활용할 수 있다. 따라서 Swarm 위성자료의 구배 성분을 이용한 지역화 모델링 방법은 앞으로 많은 활용이 기대되며 여기서는 Swarm 위성자료로부터 얻어진 지각 자기이상값의 전지구 조화함수 계수 모델을 사용하여 자기이상의 방향성분과 구배성분을 유도하고 이를 스레피안 구면 조화함수에 적용하여 관심지역인 남극지역의 방향 성분과 구배 성분을 표현하고 이에 대한 결과를 토의 하고자 한다.

• Smart Structures and Systems
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• 제3권2호
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• pp.173-188
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• 2007

The general solution for two-dimensional magneto-electro-elastic media in terms of four harmonic displacement functions is proposed analytically. The expressions of specific solutions of magneto-electro-elastic plane problems with specific body forces are derived. Finally, based on the general solution in the case of distinct eigenvalues and the specific solution for density functionally gradient media, two kinds of beam problems with body forces depending only on the z or x coordinate are solved by the trial-and-error method.