• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.380-383
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• 2003

This paper proposes a new and simple input prediction method for robust servo system. This servo system uses robust tracking control system based on both Coprime Factorization(CF) and Zero Phase Error Tracking control system. The CF control system can be designed simply and systematically. Moreover, this system has not only stability but also robustness and disturbance rejection ability The optical disk tracking servo system can detect only the tracking error. So the new and simple input prediction system proposed in this paper estimates the reference input signal from the tracking error. Numerical simulation results show that the proposed method is effective.

• Korean Journal of Mathematics
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• v.6 no.2
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• pp.319-322
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• 1998

For an M-group G, it is shown that a normal subgroup of G whose order is coprime to its index is an M-group.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.24-27
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• 1994

This paper develops a representation theory of linear systems by means of doubly coprime factorizations, and applies the theory to the simultaneous stabilization problem for a given set of linear systems.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.203-206
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• 1995

We investigate the applicability of the theory of robust stabilization with respect to additive, stable perturbations of a normalized left-coprime factorization to controller design of a flexible arm with uncertain parameters.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.5
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• pp.65-72
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• 1994

We resolve the suboptimal $\infty$ control problem using (J,J')-lossless coprime factorization by transforming the linear fractional transformation (LFT) into chain scattering description (CSD) in discrete-time systems. The condition transformed LFT into CSD is that the inverse matrix of $P_{21}$ of standard plant exists. But, this paper presents the method of transforming LFT into CSD for 4-block problem in case that the inverse matrix of $P_{21}$ of standard plant does not exist and parameterization of the all suboptimal $\infty$T controllers using (J,J')-lossless coprime factorization. It is shown that this method can resolve the suboptimal $\infty$ control problem solving only two Riccati equations in discrete-time systems.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.372-375
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• 1996

In this paper, a designing method of model following control system for linear descriptor system with disturbances is proposed. The features of this method are:1) both the physical structure of the system and the physical system variables properties can be preserved because there is no necessary to make transformation of this system. 2) boundedness of internal states are proved by means of coprime factorization of descriptor system.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.428-433
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• 1993

First, we propose a transparent and efficient design of discrete-time integral controllers accounting sampling skew. Based on the proposed controller, we derive a state-space representation of doubly coprime factorization including integral action. The representation is then used to obtain a convenient state-space parametrization of discrete-time two-degree-of-freedom integral controllers acconting sampling skew.

• Communications of the Korean Mathematical Society
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• v.35 no.2
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• pp.481-486
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• 2020

Let K be a number field. Here we give an explicit description of the group (O_K/I)* for most ideals I. In particular, we give a complete characterization of such group for those ideals I that are coprime to the different ideal 𝒟_K.

• Journal of the Korean Mathematical Society
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• v.46 no.3
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• pp.493-511
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• 2009

Let $q\;{\geq}\;3$ be an odd integer and a be an integer coprime to q. Denote by N(a, q) the number of pairs of integers b, c with $bc\;{\equiv}\;a$ (mod q), $1\;{\leq}\;b$, $c\;{\leq}\;{\frac{q-1}{2}}$ and with b, c having different parity. The main purpose of this paper is to study the sum ${\sum}^{'q}_{a=1}\;\(N(a,\;q)\;-\;\frac{{\phi}(q)}{8}\)^2$ and obtain a sharp asymptotic formula.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1304-1307
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• 1996

In this paper, we present a robust Two Degree of Freedom (TDF) $H_{\infty}$ controllers for a missile system. The feedback controller is designed to meet robust stability and disturbance rejection specifications while the prefilter is used to improve the robust model matching properties of the closed loop system. As the perturbed model, we use the normalized coprim factor perturbations. These controllers are designed using $H_{\infty}$ optimization procedures, and applied to a missile model via simulation.