• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.6
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• pp.591-597
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• 1990

As a means of controlling a plant whose dynamics is not fully known, an iterative learning control method is proposed in this paper. The proposed method employs the structure of the

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.921-923
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• 1999

In adaptive fuzzy control, fuzzy systems are used to approximate the unknown plant nonlinearities. However, because of the approximating error introduced into the feedback loop, it is difficult to guarantee the stability of the adaptive control algorithm. This paper presents a robust control algorithm against the reconstruction error and uniform boundedness of the all signals is estabilished in the Lyapunov sense.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.284-284
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• 2000

In adaptive fuzzy control systems. fuzzy systems are used to approximate the unknown plant nonlinearities. Until now. most of the papers in the field of controller design for nonlinear system using fuzzy systems considers the affine system with fixed grid-rule structure based on system state availability. This paper considers observer-based nonlinear controller and dynamic fuzzy rule structure. Adaptive laws for fuzzy parameters for state observer and fuzzy rule structure are established so that the whole system is stable in the sense of Lyapunov.

• Nuclear Engineering and Technology
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• v.44 no.3
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• pp.343-354
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• 2012

Primary water stress corrosion cracking (PWSCC) is a major safety concern in the nuclear power industry worldwide. PWSCC is known to initiate only in the condition in which sufficiently high tensile stress is applied to alloy 600 tube material or alloy 82/182 weld material in pressurized water reactor operating environments. However, it is still uncertain how much tensile stress is re-quired to generate PWSCC or what causes such high tensile stress. This study was performed to pre-dict the magnitude of weld residual stress and operating stress and compare it with previous experi-mental results for PWSCC initiation. For the study, a pressurizer safety nozzle was selected because it is reported to be vulnerable to PWSCC in overseas plants. The assessment was conducted by nu-merical analysis. Before performing stress analysis for plant conditions, a preliminary mock-up ana-lysis was done. The result of the preliminary analysis was validated by residual stress measurement in the mock-up. After verification of the analysis methodology, an analysis under plant conditions was conducted. The analysis results show that the stress level is not high enough to initiate PWSCC. If a plant is properly welded and operated, PWSCC is not likely to occur in the pressurizer safety nozzle.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.396-401
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• 2002

A practical method for evaluating the possibility of the occurrence of cracking in actual thick-plate T-joint weldments is presented in this study. Systematic experiments based on the method of the design of experiment are conducted in order to investigate the crack tendency in relation to typical welding parameters such as diffusible hydrogen, restraint intensity, preheating temperature and so on. The elastic analysis using the [mite element techniques is employed to quantify the restraint intensities of the specimens. The defined restraint intensities are treated in numerical way for the sake of considering the most uncertain factor among some major factors that govern the cracking phenomena due to welding. The critical plane for judgment of the crack occurrence or crack density is presented as a function of typical welding parameters including determined restraint intensities. The results of numerical estimation by the proposed method for the experimental specimens show the usefulness as a practical tool in welding induced crack problem having extensive uncertainties.

• Journal of the Korean Institute of Intelligent Systems
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• v.7 no.2
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• pp.43-50
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• 1997

Refuse incineration plant operations involve many kinds of uncertain factors, such as the variable physical properties of refuse as fuel and the complexity of the burning phenomenon. This makes it very dificult to apply conventional control methods to the combustion control of the refuse. So most of the refuse incineration plant are operated by operators. In this paper, an multi-variable fuzzy model predictive controller is proposed for the combustion control of the re:fuse. Adaptive network based fuzzy inference system is used for modeling of the refuse incineration plant and multi-variable fuzzy model predictive controller is designed based on the identified fuzzy model. And computer simulation was carried out to evaluate performance of the proposed controller.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2003.10b
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• pp.19-19
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• 2003

The Xylariaceae Tul. & C. Tul is a family of sphaeriaceous genera with obscure but apparently common ancestry (Rogers, 1979), A central core of genera - Xylaria, Hypoxylon, Rosellinia, Poronia, Podosordaria, Hypocopra, Daldinia, Biscogniauxia, Kretzschmaria, Camillea, Penzigia - are obviously related, regardless of the fact that the generic limits are arguable (Rogers, 1979; Barr, 1990; Eriksson & Hawksworth, 1991; Laessoe, 1994). In general, the family Xylariaceae is primarily defined as a group of stromatic pyrenomycetes with unitunicate asci characterized by a typical apical apparatus and pigmented ascospores having a germ slit (Rogers, 1979). Since Winter (1887) circumscribed the family to include Pyrenomycetes with predominately a dark stroma, dark unveiled spores containing 5 genera: Nummularia Tul. & C. Tul., Hypoxylon Bull., Ustulina Tul. & C.Tul., Poronia Willd. and XylariaHill ex Schrank, many more genera has been added to the family (Dennis, 1961; Eriksson & Hawksworth, 1993; Whalley, 1996). In the absence of a clear circumscription of the family (Rogers, 1994) the agreed number of accepted genera is governed by individual views and there are therefore difference between the proposals for the ascomycetes recognized 35 genera and indicated a further 3 which might belong there. Laessoe reviewed the family and included 37 genera but a few of these were listed as uncertain (Laessoe, 1994). In the most recent accounts Whalley (1996) listed 41 genera but again a number of these were considered uncertain and Ju and Rogers (1996) accepted 39 genera in their interpretation of the family. Since Laessoe (1994) merged Daldinia and Versiomyces with Hypoxylonand Ju and Rogers (1996) combined Astrocystis with Rosellinia and Helicogermslita, which can be argued strongly against, it is likely that a realistic number of genera will be close to 40 (Whalley, 1996; Table 1).

• Proceedings of the Plant Resources Society of Korea Conference
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• 2003.10a
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• pp.43-49
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• 2003

The Xylariaceae Tul. & C. Tul is a family of sphaeriaceous genera with obscure but apparently common ancestry (Rogers, 1979). A central core of genera - Xylaria, Hypoxylon, Rosellinia, Poronia, Podosordaria, Hypocopra, Daldinia, Biscogniauxia, Kretzschmaria, Camillea, Penzigia - are obviously related, regardless of the fact that the generic limits are arguable (Rogers, 1979; Barr, 1990; Eriksson & Hawksworth, 1991; Laessoe, 1994). In general, the family Xylariaceae is primarily defined as a group of stromatic pyrenomycetes with unitunicate asci characterized by a typical apical apparatus and pigmented ascospores having a germ slit (Rogers, 1979). Since Winter (1887) circumscribed the family to include Pyrenomycetes with predominately a dark stroma, dark unveiled spores containing 5 geners: Nummularia Tul, & C. Tul., Hypoxylon Bull., ustulina Tul. & C.Tul., Poronia Willd. and XylariaHill ex Schrank, many more genera has been added to the family (Dennis, 1961; Eriksson & Hawksworth, 1993; Whalley, 1996). In the absence of the clear circumscription of the family (Rogers, 1994) the agreed number of accepted genera is governed by individual views and there are therefore difference between the proposals for the ascomycetes recognized 35 genera and indicated a further 3 which might belong there. Laessore reviewed the family and included 37 genera but a few of these were listed as uncertain (Laessoe, 1994). In the most recent accounts Whalley (1996) listed 41 genera but again a number of these were considered uncertain and Ju and Rogers (1996) accepted 39 genera in their interpretation of the family. Since Laessoe (1994) merged Daldinia and Versiomyces with Hypoxylonand Ju and Rogers (1996) combined Astrocystis with Resellinia and Helicogermslita, which can be argued strongly against, it is likely that a realistic number of genera will be close to 40(Whalley, 1996; table 1).

• Journal of Mechanical Science and Technology
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• v.17 no.4
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• pp.484-491
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• 2003

For most of linear time-varying (LTV) systems, it is difficult to design time-varying controllers in analytic way. Accordingly, by approximating LTV systems as uncertain linear time-invariant, control design approaches such as robust control have been applied to the resulting uncertain LTI systems. In particular, a robust control method such as quantitative feedback theory (QFT) has an advantage of guaranteeing the frozen-time stability and the performance specification against plant parameter uncertainties. However, if these methods are applied to the approximated linear. time-invariant (LTI) plants with large uncertainty, the resulting control law becomes complicated and also may not become ineffective with faster dynamic behavior. In this paper, as a method to enhance the fast dynamic performance of LTV systems with bounded time-varying parameters, the approximated uncertainty of time-varying parameters are reduced by the proposed QFT parameter-scheduling control design based on radial basis function (RBF) networks.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.479-481
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• 1999

In this paper, We design low-order controller to achieve maximized controller stability margin and controller' Performance. FOPA(Fixed Order Pole Assignment) method is one of the approach to design controller in the parametric uncertain system. But the method to define a Target Polynomial is not explicit1y Known. In this paper, our goal is to find a controller Coefficient, such that performance and $l_2$ stability margin are maximized in the parametric uncertain system. Using Lipatove theorem and CDM(Coefficient Diagram Method), we set target polynomial constraints and design a controller which maximizes $l_2$ stability margin. we show effectiveness of the proposed controller design method by comparing $l_2$ stability many of the desired controller with that of the conventional robust controller.