• Journal of Institute of Control, Robotics and Systems
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• v.6 no.10
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• pp.845-853
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• 2000

In this paper, we introduce a relationship between the sensitivity and the robustness of a system, and we propose a robust eigenstructure assignment scheme using a novel performance index which can consider the performance and the robustness of the system simultaneously. We also propose an assignment accuracy measure and a robustness measure which are used for the performance examination of the proposed robust eigenstructure assignment scheme. The usefulness of the proposed algorithm and the measures are verified by applying to controller design of a simple numerical example and the EMRAAT missile.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.7
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• pp.794-799
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• 1999

This study deals with robustness bounds estimation for uncertain linear systems with structured perturbations where the eigenvalues of the perturbed systems are guaranteed to stay in a prescribed region. Based upon the Lyapunov approach, new theorems to estimate allowable perturbation parameter bounds are derived. The theorems are referred to as the zero-order or first-order asymmetric robustness measure depending on the order of the P matrix in the sense of Taylor series expansion of perturbed Lyapunov equation. It is proven that Gao's theorem for the estimation of stability robustness bounds is a special case of proposed zero-order asymmetric robustness measure for eigenvalue assignment. Robustness bounds of perturbed parameters measured by the proposed techniques are asymmetric around the origin and less conservative than those of conventional methods. Numerical examples are given to illustrate proposed methods.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.455-460
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• 1998

We propose robust MILP model for scheduling and design of multiproduct batch processes in this paper. Recent stochastic modeling approaches considering uncertainty have mainly focused on maximization of expected NPV. Robust model concept is applied to generate solution spectrum in which we can select the best solution based on tradeoff between robustness measure and expected NPV. Robustness measure is represented as penalty term in the objective function, which is Upper Partial Mean of NPV. We can quantify solution robustness by this penalty term and maintain model as MILP form to be computationally efficient. An example illustrates the effectiveness of the proposed model. In many cases sufficient robustness can be guaranteed through a little reduction of expected NPV.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.303-306
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• 1996

We propose a robust tuning method of the quadratic criterion based iterative learning control(Q-ILC) algorithm for discrete-time linear batch system. First, we establish the frequency domain representation for batch systems. Next, a robust convergence condition is derived in the frequency domain. Based on this condition, we propose to optimize the weighting matrices such that the upper bound of the robustness measure is minimized. Through numerical simulation, it is shown that the designed learning filter restores robustness under significant model uncertainty.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.48.6-48
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• 2002

in this paper, each methodology, e.g. normal single PID controller, direct synthesis method and inverse response compensator, will be compared to determine the best inverse response plant control method, by based on the appearance of the control performance and robustness from the simulation results. The flexibility of being able to maintain the system stability during the presence of plant model mismatch is one of the criteria to measure the robustness of overall control system. Once, plant has changed the condition, the model will need to be updated. Hence, the designed controller will not work properly. The caused of plant model mismatch is stayed by definition unknown but the most possib...

• Proceedings of the KSPS conference
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• 2002.11a
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• pp.205-208
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• 2002

Bimodal speech recognition based on lip reading has been studied as a representative method of speech recognition under noisy environments. There are three integration methods of speech and lip modalities as like direct identification, separate identification and dominant recording. In this paper we evaluate the robustness of lip reading methods under the assumption that lip parameters are estimated with errors. We show that the dominant recording approach is more robust than other methods with lip reading experiments. Also, a measure of lip parameter degradation is proposed. This measure can be used in the determination of weighting values of video information.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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• pp.1621-1628
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• 2004

This paper proposes a design methodology for the robust observer using the eigenstructure assignment in multi-output systems so that the observer is less sensitive to the ill-conditioning factors such as unknown initial estimation error, modeling error and measurement bias in transient and steady-state observer performance. The robustness of the observer can be achieved by selecting the desired eigenvector matrix to have a small condition number that guarantees the small upper bound of the estimation error. So the left singular vectors of the unitary matrix spanned by space of the achievable eigenvectors are selected as a desired eigenvectors. Also, this paper proposes how to select the desired eigenvector based on the measure of observability and designs the observer with small gain. An example of a spindle drive system is simulated to validate the robustness to the ill-conditioning factors in the observer performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.5
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• pp.1333-1353
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• 2012

The robustness of a network is usually measured by error tolerance and attack vulnerability. Significant research effort has been devoted to determining the network design with optimal robustness. However, little attention has been paid to the problem of how to improve the robustness of existing networks. In this paper, we investigate how to optimize attack tolerance and communication efficiency of an existing network under the limited link addition. A survival fitness metric is defined to measure both the attack tolerance and the communication efficiency of the network. We show that network topology reconfiguration optimization with limited link addition (NTRLA) problem is NP-hard. Two approximate solution methods are developed. First, we present a degree-fitness parameter to guide degree-based link addition method. Second, a preferential configuration node-protecting cycle (PCNC) method is developed to do trade-off between network robustness and efficiency. The performance of PCNC method is demonstrated by numerical experiments.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.6
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• pp.231-243
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• 2022

The objective of this study is to analyze the impact of conservative financial reporting on investment during uncertainty. It was assumed that during uncertainty conservative financial reporting can play an important role to improve investment decision-making. For our analysis, data sets from 2005-2020 of nonfinancial companies are used. To measure the impact of conservative financial reporting in the non-financial sector of Pakistan, Khan and Watts' (2009) model is applied. "Prospector" and "Defender" Business strategy is applied for measuring firm-level uncertainty. Investment is measured by adding the change in fixed assets (property, plant, and equipment). To check the robustness of conservative financial reporting, Givoly and Hayn's (2000) Negative Accruals measure is applied. To measure the robustness of uncertainty, environmental scanning and alertness technique is applied. According to environmental scanning and alertness technique, companies are divided into two groups named 'inert' and 'alert'. 'Inert' are those firms that are not scanning their environment, and 'alert' are those firms who continuously analyze their environment. The empirical estimations support our hypothesis. The empirical findings provide the proof that in the wake of uncertainty conservative financial reporting may facilitate to take optimal investment decisions in the developing economy of Pakistan. Our results provide critical and practical implications for investors, researchers, and standard setters.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.2
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• pp.122-139
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• 2008

With the proliferation of in-process measurement technology, autocorrelated data are increasingly common in industrial SPC applications. A number of high performance control charting techniques that take into account the specific characteristics of the autocorrelation through time series modeling have been proposed over the past decade. We present a survey of such methods and analyze and compare their performances for a range of typical autocorrelated process models. One practical concern with these methods is that their performances are often strongly affected by errors in the time series models used to represent the autocorrelation. We also provide some analytical results comparing the robustness of the various methods with respect to time series modeling errors.