• 대한수학회보
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• 제48권6호
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• pp.1303-1314
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• 2011

We consider meromorphic solutions of q-difference equations of the form $$\sum_{j=o}^{n}a_j(z)f(q^jz)=a_{n+1}(z),$$ where $a_0(z)$, ${\ldots}$, $a_{n+1}(z)$ are meromorphic functions, $a_0(z)a_n(z)$ ≢ 0 and $q{\in}\mathbb{C}$ such that 0 < |q| ${\leq}$ 1. We give a new estimate on the upper bound for the length of the gap in the power series of entire solutions for the case 0 < |q| < 1 and n = 2. Some growth estimates for meromorphic solutions are also given in the cases 0 < |q| < 1. Moreover, we investigate zeros and poles of meromorphic solutions for the case |q| = 1.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.664-669
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• 2005

In this note, we present a different asymptotes from the standard approximate lines of the Bode magnitude plot. Wherein the pseudo break frequency is defined in terms of coefficients of denominator and numerator polynomials of the transfer function instead of its poles and zeros. Several comparative examples are given. This result can be used for the characteristic ratio assignment(CRA) [1], [2] with frequency response requirements, which is a method of designing linear controller in parameter space.

• 제어로봇시스템학회논문지
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• 제16권3호
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• pp.222-226
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• 2010

In this paper we study the consensus problem of SISO (Single-Input Single-Output) linear multi-agent systems under a fixed weighted undirected network communication. The dynamics of each agent can be of any order, while it is constrained to be neutrally stable. Based on a simple root locus argument, we show that the problem at hand is always solvable if the gain and zeros of the dynamic compensator, of which dimension is the same as the number of plant poles on the imaginary axis, are chosen suitably, finally the result is successfully verified by an example.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(I)
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• pp.185-189
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• 1987

An analysis and design of large-scale linear multivariable systems often requires to be block triangularized form for good sensitivity of the systems when their poles and zeros are varied. But the decomposition algorithms presented up to now need a procedure of permutation, rescaling and a solution of nonlinear algebraic equations, which are usually burden. To avoid these problem, in this paper we develop a newly alternative block triangular decomposition algorithm which used the generalized matrix sign function on the Z-plane. Also, the decomposition algorithm demonstrated using the fifth order linear model of a distillation tower system.

• 대한전자공학회논문지
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• 제24권1호
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• pp.52-59
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• 1987

A new on-line estimation algorithm for a time varying time delay is proposed. This algorithm is based on the concept of minimization of prediction error. As only the parameters directly related to the poles and zeros of the process are estimated in the algorithm, persistently exciting condition for the convergence of parameters can be less restrictive. Under some assumptions which is necessary in adaptive control, it is shown that this algorithm estimates time varying time delay accurately. In view of computational burden, this algorithm needs far less amount of calculations than other methods. The larger the time delay is, the more effective this algorithm is . Computer simulation shows good properties of the algorithm. This algorithm can be used effectively in adaptive control of large dead time processes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.1012-1014
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• 2001

The AT Forward MRC is studied on the stability. The compensator is composed of the error amp with 3 poles and 2 zeros. This is optimized through the experiment. The converter loop gain is measured using HP4194A. We are initiated by the thinking of how to make the stabilization from the experimental results of loop gam curves. The loop gain, low frequency gain and gain margin are more improved through the experimental considerations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1978-1982
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• 2005

In this paper, a linear controller is designed for the longitudinal model of X-33 in TAEM (The Terminal Area Energy Management) phase. The CRA (Characteristic Ratio Assignment) is used as the continuous time design method such that the output response of X-33 control system tracks the reference command. The performance of the proposed controller is evaluated through the step response. Also simulation results show that the initial state of the plant is dominantly affected by the poles and zeros of the plant.

• 한국음향학회지
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• 제29권5호
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• pp.339-346
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• 2010

음향 간섭제거기는 머리전달함수 (head-related impulse response; HRIR)의 길이에 큰 영향을 받게 되어, 일반적으로 큰 차수의 필터를 필요로 한다. 간섭제거필터의 길이를 줄이기 위한 방법으로 주파수 워핑, 공통 극점과 영점 (common acoustical pole and zero; CAPZ) 모델링 등의 방법들이 제안되었는데, 본 논문에서는 이 두 가지 방법을 결합한 방법을 제안한다. 이를 위해, 주파수 워핑 영역에서 공통 극점과 영점 모델링을 통해 필터를 설계하며, 디워핑 과정을 통해 종래의 선형 영역에서 안정된 필터를 구현한다. 제안된 방법은 주파수 워핑을 통한 간섭제거 성능 향상과 공통 극점 모델링을 통한 필터 계수 감소를 함께 제공할 수 있다. 이러한 성능을 검증하기 위해 다양한 컴퓨터 모의 실험을 진행하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.428-432
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• 2003

Quantitative Feedback Theory (QFT) is one of most effective methods of robust controller design and can be considered as a suitable method for systems with parametric uncertainties. Particularly it allows us to obtain controllers less conservative than other methods like $H_{\infty}$ and ${\mu}$-synthesis. In QFT method, we transform all the uncertainties and desired specifications to some boundaries in Nichols chart and then we have to find the nominal loop transfer function such that satisfies the boundaries and has the minimum high frequency gain. The major drawback of the QFT method is that there is no effective and useful method for finding this nominal loop transfer function. The usual approach to this problem involves loop-shaping in the Nichols chart by manipulating the poles and zeros of the nominal loop transfer function. This process now aided by recently developed computer aided design tools proceeds by trial and error and its success often depends heavily on the experience of the loop-shaper. Thus for the novice and First time QFT user, there is a genuine need for an automatic loop-shaping tool to generate a first-cut solution. In this paper, we approach the automatic QFT loop-shaping problem by using an algorithm involving Linear Programming (LP) techniques and Genetic Algorithm (GA).

• Journal of electromagnetic engineering and science
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• 제9권3호
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• pp.164-173
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• 2009

In this paper, two new circuit structures for European and U.S. ultra-wide band(UWB) bandpass filters(BPFs) with sharp roll-off characteristics are introduced. We show first that the ultra-wide bandpass property is obtained from a $\lambda$/4 open T resonator with a capacitively coupled $\lambda$/4 short-circuited line, which provides two attenuation poles at lower and upper cutoff frequencies. Then, two identical capacitively coupled input/output lines, which can be $\lambda$/4-length open ends or $\lambda$/2-length short ends, with the T-resonator, are adopted to suppress lower and higher frequency components outside of the pass band. There is coupling between the input and output lines providing two additional transmission zeros in the lower and upper transition bands of the filter. Since the coupling between the T-resonator with the $\lambda$/4 short-circuited line and the input/output lines limits the bandwidth of the filter to the European UWB band, both the $\lambda$/4 short-circuited line and the input/output lines are inserted between the two stacked T-resonators for the U.S. UWB band. The filter structures are simulated with ADS and HFSS and realized with low-temperature co-fired ceramic(LTCC) green tape which has the dielectric constant of 7.8. Measurement results agree well with HFSS simulation results.