• Journal of Power Electronics
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• v.15 no.3
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• pp.796-805
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• 2015

New direct and indirect current control methods for a fault-tolerant active power filter topology are presented in this paper. Since a three-phase four-switch topology has a phase bridge current which cannot be directly controlled, a hysteresis control method in the α-β plane which controls the three-phase current in the two-phase stationary coordinate system is proposed. The improved SVPWM algorithm is able to eliminate the operation of the trigonometric functions in the traditional algorithm by rotating the α-β coordinates and alternating the sequence of the output vectors, which in turn simplifies the algorithm and reduces the switching frequency. The selection of the DC-side reference voltage and DC-side capacitor equalization strategy are also discussed. Simulation and experiments demonstrate that the proposed control method is correct and feasible.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.40 no.6
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• pp.1-8
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• 2003

A novel CORDIC circuit is presented based on a redundant number system eliminating global carry Propagation. The number format employs a new recoding scheme similar to the Booth receding resolving carry problems in addition. A pipelined architecture is introduced having a constant scale factor in its computation of trigonometric functions. The operational time of the circuit is constant independent of the number of operand digits.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.589-592
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• 2004

The CORDIC algorithm can be implemented very simple H/W, but needs a lot of latency to compute trigonometric function. The RA(Redundant Arithmetic) resolves this problem, but also has difficulty to determine the directions of micro-rotations. The pre-computed direction of micro-rotation algorithm relieves the RA of this matter. In this paper, we proposed the modified the pre-computed algorithm adopted with a table-lookup. Instead of reducing H/W complexity, its performance and calculation errors are improved.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.4
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• pp.473-481
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• 2012

For a mesa-isolated small geometry SOI MOSFET, the potentials in the silicon film, front, back, and side-wall oxide layers can be derived three-dimensionally. Using Taylor's series expansions of the trigonometric functions, the derived potentials are written in terms of the natural length that can be determined by using the derived formula. From the derived 3-D potentials, the minimum values of the front and the back surface potentials are derived and used to obtain the closed-form expressions for the front and back gate threshold voltages as functions of various device parameters and applied bias voltages. Obtained results can be found to explain the drain-induced threshold voltage roll-off and the narrow width effect of a fully depleted small geometry SOI MOSFET in a unified manner.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.85-88
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• 1999

Adapted Local Trigonometric Transforms은 매우 높은 energy compaction을 가지므로 음성 및 영상신호에 이용하려는 시도가 이루어지고 있다. [1] 그러나 이 경우 복원 된 신호에는 시간 영역에서 불연속점이 발생하여 일종의 tick noise가 발생한다. 또한 phase성분을 잃게 되어 금속성 잡음도 추가하여 나타난다. 본 논문에서는 이러한 문제점을 해결하기 위한 Polynomial fitting 방식과 Wavelet Packet Transforms 방식을 제안한다. Polynomial fitting 방식으로는 시간축상에서 발생하는 문제를 해결하고 Wavelet Packet Transforms으로 Phase 문제를 해결한다. [2,3] 실험결과, 압축이전의 신호와 비교할 때 SNR에 있어서 개선을 보이며 tick noise와 금속성 잡음이 제거된 개선된 신호음을 확인 할 수 있었다.

• Steel and Composite Structures
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• v.27 no.1
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• pp.1-12
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• 2018

This paper presents a semi-analytical solution of simply supported horizontally composite curved I-beam by trigonometric series. The flexibility of the interlayer connectors between layers both in the tangential direction and in the radial direction is taken into account in the proposed formulation. The governing differential equations and the boundary conditions are established by applying the variational approach, which are solved by applying the Fourier series expansion method. The accuracy and efficiency of the proposed formulation are validated by comparing its results with both experimental results reported in the literature and FEM results.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.412-417
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• 1998

This paper provides accurate flexural vibration solutions for thick (Mindlin) sectorial plates. A Ritz method is employed which incorporates a complete set of admissible algebraic-trigonometric polynomials in conjunction with an admissible set of Mindlin “corner functions". These corner functions model the singular vibratory moments and shear forces, which simultaneously exist at the vertex of corner angle exceeding 180$^{\circ}$. The first set guarantees convergence to the exact frequencies as sufficient terms are taken. The second set represents the corner singularities, and accelerates convergence substantially. Numerical results are obtained for completely free sectorial plates. Accurate frequencies are presented for a wide spectrum of vertex angles (90$^{\circ}$, 180$^{\circ}$, 270$^{\circ}$, 300$^{\circ}$, 330$^{\circ}$, 350$^{\circ}$, 35 5$^{\circ}$,and 359$^{\circ}$)and thickness ratios.tios.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.1
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• pp.145-149
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• 2015

A reconfigurable lighting engine for widely used lighting models is proposed for low-power GPU shaders. Conventionally, lighting operations that involve many complex arithmetic operations were calculated by the shader programs on the GPU, which led to a significant energy overhead. In this letter, we propose a lighting engine to improve the energy-efficiency by supporting the widely used advanced lighting models in hardware. It supports the Blinn-Phong, Oren-Nayar, and Cook-Torrance models, by exploiting the logarithmic arithmetic and optimizing the trigonometric function evaluations for the energy-efficiency. Experimental results demonstrate 12.7%, 42.5%, and 35.5% reductions in terms of power-delay product from the shader program implementations for each lighting model. Moreover, our work shows 10.1% higher energy-efficiency for the Blinn-Phong model compared to the prior art.

• Journal of applied mathematics & informatics
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• v.26 no.1_2
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• pp.317-324
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• 2008

This paper shows the degree of simultaneous neural network approximation for a target function in $C^r$[-1, 1] and its first derivative. We use the Jackson's theorem for differentiable functions to get a degree of approximation to a target function by algebraic polynomials and trigonometric polynomials. We also make use of the de La Vall$\grave{e}$e Poussin sum to get an approximation order by algebraic polynomials to the derivative of a target function. By showing that the divided difference with a generalized translation network can be arbitrarily closed to algebraic polynomials on [-1, 1], we obtain the degree of simultaneous approximation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.4
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• pp.336-343
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• 2004

This paper reports the first known free vibration data for thin rectangular plates with V-notches. The classical Ritz method is employed with two sets of admissible functions assumed for the transverse vibratory displacements. These sets include (1) mathematically complete algebraic-trigonometric polynomials which guarantee convergence to exact frequencies as sufficient terms are retained, and (2) corner functions which account for the bending moment singularities at the sharp reentrant corner of the Y-notch. Extensive convergence studies summarized herein confirm that the corner functions substantially enhance the convergence and accuracy of nondirectional frequencies for rectangular plates having the V-notch. In this paper, accurate frequencies and normalized contours of vibratory transverse displacement are presented for various notched plates, so that the effect of corner stress singularities may be understood.