• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2007.12a
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• pp.307-308
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• 2007

In general, most physical systems are complex, highly non-linearity, affected by disturbance, incomplete knowledge, and even interactive change with the operating points. To solve this problem, the research of modem control theory and controller is proceeding. Before appling the proposed controller to the real system, however, it needs an apparatus which can verify the proposed controller for being not damaged the plant. In this paper, therefore, a RCGA-based PI-type state feedback controller using reduced-order observer is implemented and applied to the seesaw system and a series of simulation are carried out to verify the effectiveness of the control system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.7
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• pp.601-608
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• 2015

The static aeroelastic analysis and optimization of flexible wings are conducted for steady state conditions while both aerodynamic and structural parameters can be used as optimization variables. The system of multidisciplinary design optimization as a robust methodology to couple commercial codes for a static aeroelastic optimization purpose to yield a convenient adaptation to engineering applications is developed. Aspect ratio, taper ratio, sweepback angle are chosen as optimization variables and the skin thickness of the wing. The real-coded adaptive range multi-objective genetic algorithm code, which represents the global multi-objective optimization algorithm, was used to control the optimization process. The support vector regression(SVR) is applied for optimization, in order to reduce the time of computation. For this multi-objective design optimization problem, numerical results show that several useful Pareto optimal designs exist for the flexible wing.

• Journal of the Korean Geotechnical Society
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• v.20 no.6
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• pp.85-94
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• 2004

In the companion paper, a constitutive model was proposed in order to represent brittleness and dilatancy for cohesionless soils. An optimized design methodology was proposed on the basis of real-coded genetic algorithm in order to determine parameters fir the proposed model systematically. The material parameters were then determined by that algorithm. In order to verify the proposed model, triaxial tests were peformed under $K_0$ conditions for weathered soils. In addition, the results of istropic compressed triaxial tests for granular materials verified the proposed model. For those results the brittle stress-strain relationship and the dilatancy could be modeled reasonably by the proposed model. As a result it was found that the proposed model can appropriately represent the behavior on weathered soil and granular soil.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.1
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• pp.33-38
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• 2002

In this paper, a Two-Degree-of-Freedom-Controller(TDFC) for DC motors based on inverse dynamics and the fuzzy technique is presented. The proposed controller includes the inverse dynamic model of a DC motor system, a prefilter and a fuzzy compensator. The model of the system is characterized by a nonlinear equation with coulomb friction. The prefilter eliminates high frequency effects occurring when the inverse dynamic model is implemented. The fuzzy compensator is designed for tracking the change of the reference input and simultaneously regulating the error between the reference input and the system output which can be caused by disturbances. The optimal parameters of both the model and the compensator are identified by a real-coded genetic algorithm. An experimental work on a DC motor system is carried out to verify the performance of the proposed controller.

• Journal of Korea Water Resources Association
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• v.39 no.1 s.162
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• pp.47-57
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• 2006

This study derives an event-based tank model with a conceptual rainfall-infiltration process, modifying conventional tank models. The model comprises two serial tanks, one parallel tank and an infiltration regulating element. The infiltration process within the element is not represented as a function of only time, but as a function of soil moisture content for three possible cases owing to the relationship between rainfall intensity and infiltration capacity. This study considers the previous soil moisture condition of a watershed by using antecedent precipitation index. Six parameters of the model are identified by using the real coded genetic algorithm. The applicability and validity of the proposed model are assessed for the observed stormwater data from the research basin of the International Hydrological Program, the Pyeongchanggang River basin, Republic of Korea. The results computed streamflows show relatively good agreement with observed ones.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.749-754
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• 2005

본 연구에서는 한 개의 침투 조절 요소, 두 개의 직렬탱크 및 한 개의 병렬 탱크로 구성된 개선된 형태의 TANK 모형을 제시하였다. 침투는 강우의 형태로 유역에 공급되는 물의 분배를 결정하는 과정으로서, 이를 적절히 고려할 수 있는지의 여부가 강우-유출 모형의 유효성을 판단하는 기준이 된다고 해도 과언이 아니다. 따라서 본 연구에서는 구조가 비교적 단순하고 사용이 간편하여 기존에 널리 사용되어 오던 개념적 모형인 TANK 모형에 침투 조절 요소를 도입하여 보다 합리적으로 강우-침투-유출 과정을 모의하고 해석하고자 노력하였다. 이를 통해 단순히 시간의 함수가 아닌 토양 함수량의 함수로서 침투능의 변화를 고려할 수 있으며, 유역 유출의 각 성분(지표면 유출, 중간 유출, 지하수 유출)에 영향을 미치는 모형의 매개변수에 물리적 의미를 더욱 부여할 수 있다. 또한 침투 조절 요소의 매개변수 산정을 위해 선행 강우 지수(Antecedent Precipitation Index)를 이용하였으며, 이를 통해 토양 선행 함수 상태의 고려가 가능하다. 또한 본 연구에서는 모형의 매개변수 최적화를 위해 실수 코딩 유전 알고리즘(Real Coded Genetic Algorithm)을 사용하였으며, 모형의 적용성과 유효성 검증을 위해 IHP 연구 유역인 평창강 방림 유역을 대상유역으로 하여 이 유역의 실측 호우 사상을 사용하였다. 결과적으로 계산된 수문곡선은 관측치에 비교적 잘 일치하며, 단일 호우와 복합 호우 사상 모두에 대해 비교적 양호한 결과를 나타내었다.

• Journal of Electrical Engineering and Technology
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• v.8 no.3
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• pp.402-410
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• 2013

In this paper, a novel and robust Power System Stabilizer (PSS) is proposed as an effective approach to improve stability in electric power systems. The dynamic performance of proposed PSS has been thoroughly compared with Conventional PSS (CPSS). Both the Real Coded Genetic Algorithm (RCGA) and Particle Swarm Optimization (PSO) techniques are applied to optimum tune the parameter of both the proposed PSS and CPSS in order to damp-out power system oscillations. Due to the high sufficiency of both the RCGA and PSO techniques to solve the very non-linear objective, they have been employed for solution of the optimization problem. In order to verify the dynamic performance of these devices, different conditions of disturbance are taken into account in Single Machine Infinite Bus (SMIB) power system. Moreover, to ensure the robustness of proposed PSS in damping the power system multi-mode oscillations, a Multi Machine (MM) power system under various disturbances are considered as a test system. The results of nonlinear simulation strongly suggest that the proposed PSS significantly enhances the power system dynamic stability in both of the SMIB and MM power system as compared to CPSS.

• Journal of Navigation and Port Research
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• v.34 no.2
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• pp.117-122
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• 2010

Since fuzzy controllers are nonlinear, it is more difficult to set the controller gains and to analyse the stability compared to conventional PID controllers. This paper proposes a fuzzy PD+I controller for tracking control which uses a linear fuzzy inference(product-sum-gravity) method based on a conventional linear PID controller. In this scheme the fuzzy PD+I controller works similar to the control performance as the linear PD plus I(PD+I) controller. Thus it is possible to analyse and design an fuzzy PD+I controller for given systems based on a linear fuzzy PD controller. The scaling factors tuning scheme, another topic of fuzzy controller design procedure, is also introduced in order to fine performance of the fuzzy PD+I controller. The scaling factors are adjusted by a real-coded genetic algorithm(RCGA) in off-line. The simulation results show the effectiveness of the proposed fuzzy PD+I controller for tracking control problems by comparing with the conventional PID controllers.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.181-189
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• 2013

In this paper, we introduce the fuzzy neural network based on the individual input space to design the pattern recognizer. The proposed networks configure the network by individually dividing each input space. The premise part of the networks is independently composed of the fuzzy partition of individual input spaces and the consequence part of the networks is represented by polynomial functions. The learning of fuzzy neural networks is realized by adjusting connection weights of the neurons in the consequent part of the fuzzy rules and it follows a back-propagation algorithm. In addition, in order to optimize the parameters of the proposed network, we use real-coded genetic algorithms. Finally, we design the optimized pattern recognizer using the experimental data for pattern recognition.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.9
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• pp.717-722
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• 2001

This paper presents a methodology on the backward path tracking control of a trailer type robot which consists of two parts: a tractor and a trailer. It is difficult to control the motion of a trailer vehicle since its dynamics is non-holonomic. Therefore, in this paper, the modeling and parameter estimation of the system using a real-coded genetic algorithm(RCGA) is proposed and a backward path tracking control algorithm is then obtained based on the linearized model. Experimental results verify the effectiveness of the proposed method.