• Journal of electromagnetic engineering and science
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• v.2 no.2
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• pp.124-127
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• 2002

A RF tunable bandpass filter using dielectric resonators and varactor diodes is redesigned to improve the passband flatness. Since the tunable liters are generally of narrow bandwidth and the Q value of the varactor diode is usually very low, the passband flatness is strongly deteriorated by sizeable distortion loss. To remedy this problem, we construct modified Chebyshev type filter by use of network synthesis techniques. The key of modified Chebyshev type filter is the rearrangement of the passband poles to improve the passband flatness. To maintain the constant passband bandwidth, design techniques of input/output stage and coupling windows are also applied. Experimental results show that the passband flatness can be improved by purposed method without any additional RF amplitude equalizer.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.772-774
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• 1997

Small-signal stability analysis of large power systems needs the calculation of eigenvalues. But we use the partial eigenanalysis to calculate rightmost eigenvalues, since system matrix is very large. This paper proposes the Arnoldi-Chebyshev method identifying rightmost eigenvalues. This method constructs an optimal ellipse containing unwanted eigenvalues and use the Chebyshev iteration to get approximate eigenvetors corresponding to wanted eigenvalues, and then applies the modified Arnoldi method to calculate wanted eigenvalues.

• ETRI Journal
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• v.29 no.5
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• pp.670-672
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• 2007

An ultra-wideband low-noise amplifier is proposed with operation up to 8.2 GHz. The amplifier is fabricated with a 0.18-${\mu}m$ CMOS process and adopts a two-stage cascode architecture and a simplified Chebyshev filter for high gain, wide band, input-impedance matching, and low noise. The gain of 19.2 dB and minimum noise figure of 3.3 dB are measured over 3.4 to 8.2 GHz while consuming 17.3 mW of power. The Proposed UWB LNA achieves a measured power-gain bandwidth product of 399.4 GHz.

• Bulletin of the Korean Mathematical Society
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• v.53 no.2
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• pp.423-440
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• 2016

The bubble stabilization technique of Chebyshev-Legendre high-order element methods for one dimensional advection-diffusion equation is analyzed for the proposed scheme by Canuto and Puppo in [8]. We also analyze the finite element lower-order preconditioner for the proposed stabilized linear system. Further, the numerical results are provided to support the developed theories for the convergence and preconditioning.

• Bulletin of the Korean Mathematical Society
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• v.48 no.3
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• pp.469-474
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• 2011

The Kauffman bracket skein module $K_t$(M) of a 3-manifold M becomes an algebra for t = -1. We prove that this algebra has no non-trivial nilpotent elements for M being the exterior of the twist knot in 3-sphere and, therefore, it is isomorphic to the $SL_2(\mathbb{C})$-character ring of the fundamental group of M. Our proof is based on some properties of Chebyshev polynomials.

• Management Science and Financial Engineering
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• v.21 no.2
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• pp.25-30
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• 2015

This short article compares different solution methods for a basic RBC model (Hansen, 1985). We solve and simulate the model using two main algorithms: the methods of perturbation and projection, respectively. One novelty is that we offer a type of the hybrid method: we compute easily a second-order approximation to decision rules and use that approximation as an initial guess for finding Chebyshev polynomials. We also find that the second-order perturbation method is most competitive in terms of accuracy for standard RBC model.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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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 Mechanical Science and Technology
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• v.19 no.9
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• pp.1753-1760
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• 2005

The pseudo spectral method is applied to the free vibration analysis of double-span Timoshenko beams. The analysis is based on the Chebyshev polynomials. Each section of the double-span beam has its own basis functions, and the continuity conditions at the intermediate support as well as the boundary conditions are treated separately as the constraints of the basis functions. Natural frequencies are provided for different thickness-to-length ratios and for different span ratios, which agree with those of Euler-Bernoulli beams when the thickness-to-length ratio is small but deviate considerably as the thickness-to-length ratio grows larger.

• Communications of the Korean Mathematical Society
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• v.16 no.1
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• pp.153-161
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• 2001

In the course of working on the preconditioning $C^1$ polynomial spline collocation method, one has to deal with the exponential decay of $C^1$ Lagrange polynomial splines. In this paper we show the exponential decay of $C^1$ Lagrange polynomial splines using the Chebyshev-Gauss points as the local data points.

• Kyungpook Mathematical Journal
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• v.52 no.3
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• pp.347-357
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• 2012

When Newton's method, or Halley's method is used to approximate the pth root of 1-z, a sequence of rational functions is obtained. In this paper, a beautiful formula for these rational functions is proved in the square root case, using an interesting link to Chebyshev's polynomials. It allows the determination of the sign of the coefficients of the power series expansion of these rational functions. This answers positively the square root case of a proposed conjecture by Guo(2010).