• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1845-1847
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• 1991

In general, it is not easy to find the linearizing coordinate transformation map for a class of systems which are state equivalent to linear systems, because it is required to solve a set of partial differential equations. It is possible to construct an arbitrary nonlinear function with a backpropagation(BP) net. Utilizing this property of BP neural net, we construct a desired linearizing coordinate transformation map. That is, we implement a unknown coordinate transformation map through the training of neural weights. We have shown an example which supports this idea.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.476-481
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• 1991

This paper investigates the relationship between the two problems, supervisor reduction and observation function (projection) design, which arise in supervisory control of DEDS. It is shown through an example that a reduced supervisor of minimal size does not necessarily result in a maximal projection when a projection design method which uses the transition structure of a supervisor is applied. Also, if an L-realizable projection P is available and if a supervisor has a special structural feature, a cover C for supervisor reduction can be easily obtained. By investigating the control-compatibility of states of the reduced supervisor based on C, we can also check maximality of P in a simple manner.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.947-951
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• 1989

A Class of nonlinear distributed parameter control problems is first stated in a partial differential equation form in multi-index notion and then converted into an integral equation form. Necessary conditions for optimality in the form of maximum principle are then derived in Sobolev space W$^{l}$, p/(1 leq. p .leq. .inf.)..

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.550-554
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• 1992

In this paper the issue of convergence rate is introduced for a learning control scheme we have developed and applied for tracking of unknown linear systems. A sufficient condition under which the output trajectory converges exponentially fast is obtained using the controllability grammian of controllable linear systems. Under the same condition it is also shown that the learning control input converges exponentially with the same rate as the rate of output convergence. A numerical example with computer simulation results is presented to show the feasibility of the scheme.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.68-72
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• 1986

Upper bounds of the perturbed Co-semigroups of the infinite dimensional systems are investigated by using the algebraic Riccati equation(ARE). In the case that the solution P of the ARE is strictly positive, the perturbed semigroups are uniformly bounded. A sufficient condition for the solution P to be strictly positive is provided. The uniform boundedness plays an important role in extending approximately weak stability to weak stability on th whole space. Exponential Stability of the perturbed semigroups is studied by using the Young's inequlity. Some further discussions on the uniform boundedness of the perturbed semigroups are given.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.780-785
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• 2004

The work presented here deals with controller design by graphical method based on proportional control ramp response. The design aims at the improvement of transient response, disturbance rejection capability, steady-state error reduction with stability preservation. The first step is to generate tracking-error curve with proportional control only and decide the added error signal shape on the error curve. The effectiveness of the proposed controller is confirmed through the simulation and experiment.

• 전기의세계
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• v.20 no.1
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• pp.9-18
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• 1971

The characteristics of optimum control for the second order P.W.M. sampled-data system with linear plants are investigated, with the development of method for finding the cannonical represetations for the initial states, as well as the optimality of modulator output for the P.W.M. system, which contains the electro-mechanical components, by dividing the phase plane into several regions, in which the position of the system in the phase plane are converted into the pulse polarity and pulse width.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2152-2154
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• 2002

신경망을 이용한 적응제어는 학습능력에 따라 외란작용에 스스로 대처하고, 정밀한 제어가 가능하지만 학습파라미터가 최적화되기 전에는 불안정한 제어응답을 보인다. 퍼지논리는 전문가의 경험을 논리화한 것으로 제어특성은 좋으나, 외란에 대한 적응력이 부족하여 계속적인 오프셋이 발생할 수 있다. 따라서, 퍼지와 신경망을 시스템의 동특성에 따라 혼용한 제어방식을 제시하고, 시뮬레이션으로 시간지연이 있는 CSTH의 온도와 비선형 공정인 pH 중화공정에 적용하여 단순신경망 제어어보다 개선된 제어응답 특성을 얻었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.5
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• pp.1059-1065
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• 2005

In this study, an nutrient solution control system have been designed and implemented, which controls the density of nutrient and the nutrient supply automatically using embedded real time operating system and fuzzy control algorithm. The factors which affect the growth of crop consist of solar radiation, external temperature, and external humidity. Also, nutrient temperature, electric conductivity(ED, and pH are monitored. According to the surveyed results, a fuzzy control algorithm for nutrient control is developed in order to control the density of nutrient and the nutrient supply. The exclusive embedded controller which consists of an embedded real time operating system, a korean LCD, and a graphic is developed for common users.

• Journal of Wetlands Research
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• v.13 no.3
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• pp.489-497
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• 2011

In this study the main purpose is to reduce non-point source pollution and improve water quality of Hoeya reservoir using constructed wetlands. As part of the efforts to improve water quality of the reservoir, cattail and reed-wetland cells were constructed in front of the reservoir to remove nitrogen(N) and phosphorus(P). Also, effects of hydraulic and seasonal variation on removal efficiencies of N and P were investigated. Total P and N removal efficiencies of the wetland system were approximately 20.7% and 42.7%, respectively. Removal efficiencies of N and P during the growth season (july to august) and blooming season of cattail and reed (september to october) were higher than other seasons. These results suggest that wetland system could be an effective alternative for control of non-point source pollutnat such as N and P of reservoir.