• Transactions on Control, Automation and Systems Engineering
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• 제3권2호
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• pp.95-105
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• 2001

In this paper, in order to control uncertain chaotic system, an adaptive fuzzy control(AFC) scheme is developed for the multi-input/multi-output plants represented by the Takagi-Sugeno(T-S) fuzzy models. The proposed AFC scheme provides robust tracking of a desired signal for the T-S fuzzy systems with uncertain parameters. The developed control law and adaptive law guarantee the boundedness of all signals in the closed-loop system. In addition, the chaotic state tracks the state of the stable reference model(SRM) asymptotically with time for any bounded reference input signal. The suggested AFC design technique is applied for the control of an uncertain Lorenz system based on T-S fuzzy model such as stabilization, synchronization and chaotic model following control(CMFC).

• Journal of information and communication convergence engineering
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• 제12권2호
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• pp.67-74
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• 2014

In multi-hop communication systems, two-way relaying is one of the solutions to mitigate the spectral efficiency loss caused by a half-duplex transmission. In this paper, a simple two-way relaying scheme is proposed for two-hop two-user multiple input multiple output (MIMO) systems. In the proposed system, a base station and a relay station (RS), both equipped with two antennas, form a point-to-point MIMO channel, while the RS and two single-antenna mobile users form a point-to-multipoint multiuser (MU)-MIMO channel. Numerical examples show that the proposed system achieves a significant sum rate gain as compared to a one-way relaying system as the distance between a relay and the two users decreases. We also show that although we can expand the proposed scheme to more than two users, its performance gain as compared to that of one-way relaying decreases with an increase in the number of users.

• 컴퓨터교육학회논문지
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• 제11권6호
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• pp.95-102
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• 2008

본 연구에서 SDG를 사용한 교육 퍼즐구현을 통하여 협동학습을 컴퓨터교육에 적용하였다. SDG란 하나의 컴퓨터 디스플레이에 다중 입력장치로 협동적인 작업을 할 수 있는 시스템을 말한다. SDG 기반의 협동학습을 통해 학습자들은 협동 학습을 수행하게 된다. SDG를 이용한 협동학습이 단일 디바이스를 이용한 개별 학습보다 우월하다는 기존의 연구가 있다. 이를 바탕으로 협동학습을 이용한 퍼즐게임을 구현하였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권3호
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• pp.127-133
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• 2005

Korean multi-propulsion system consists of a synchronous alternator driven by a gas turbine driving synchronous alternator coupled to a rectifier - DC link - DC/DC converter and traction system based on modification of the G7 high-speed train. The simulation modules include turbine engine system, alternator, rectifier, DC/DC converter and power management module. Simulation for the multi-propulsion system such as a modular is presented in order to confirm the system stability for loads with uncertain input impedances and control loop speeds. This paper deals with various simulation modules with a specific control loop to help the development of the real lame-scaled system.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2000년도 춘계학술대회 학술발표 논문집
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• pp.47-50
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• 2000

In this paper, an optimal identification method using Multi-FNN(Fuzzy-Neural Network) is proposed for model ins of nonlinear complex system. In order to control of nonlinear process with complexity and uncertainty of data, proposed model use a HCM clustering algorithm which carry out the input-output data preprocessing function and Genetic Algorithm which carry out optimization of model. The proposed Multi-FNN is based on Yamakawa's FNN and it uses simplified inference as fuzzy inference method and Error Back Propagation Algorithm as learning rules. HCM clustering method which carry out the data preprocessing function for system modeling, is utilized to determine the structure of Multi-FNN by means of the divisions of input-output space. Also, the parameters of Multi-FNN model such as apexes of membership function, learning rates and momentum coefficients are adjusted using genetic algorithms. Also, a performance index with a weighting factor is presented to achieve a sound balance between approximation and generalization abilities of the model, To evaluate the performance of the proposed model, we use the time series data for gas furnace and the numerical data of nonlinear function.

• 대한전자공학회논문지TC
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• 제45권6호
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• pp.13-19
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• 2008

이 논문에서는MIMO(Multi-Input Multi-Out)-OFDM(Orthogonal Frequency Division Multiplexing) 시스템에 다중 안테나를 가진 relay를 적용 할 경우, cooperation 통신을 하기 위한 기법을 제안하고 성능을 분석한다. 이동국과 relay간 뿐만 아니라 relay와 기지국간에도 STC(space time coding)에 의해 MIMO채널이 형성되어 cooperative diversity와 MIMO에 의한 diversity 이득을 함께 얻을 수 있어 시스템의 성능이 크게 향상된다. 또한 이동국과 relay에서 송신전력을 위한 간략화 된 전력할당 기법을 제안하여 이에 따른 시스템의 성능이 향상됨을 분석한다.

• 설비공학논문집
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• 제26권12호
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• pp.579-587
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• 2014

This paper deals with precise analytical state equation modeling of a variable speed refrigeration system (VSRS) for optimum control in state space. The VSRS is described as multi-input and multi-output (MIMO) system, which has two controlled variables and two control inputs. First, the Navier-Stokes equation and mass flow rate were applied to each component of the basic refrigeration cycle to build a dynamic model. The dynamic model, represented by a differential equation, was transformed into the state equation formula. Next, a full-order state observer was built to estimate all of the state variables to compose an optimum control system. Then, an optimum controller was designed to minimize an evaluation function that has input energy and control error. Finally, simulations and experiments were conducted to verify the validity of the proposed modeling and designed optimum controller to regulate target temperature and superheat in a 1RT oil cooler system. The results show that the proposed method, state equation modeling and optimum control, is efficient to ensure optimal control performance of the VSRS.

• 한국조명전기설비학회지:조명전기설비
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• 제9권4호
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• pp.78-85
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• 1995

This paper covers stability and stabilization of Multi-Excited Induction Motor used in numberous electric equipment system of industrial field. The induction motor with multi-excitation has tow sets of three-phase system : One is connected to the AC source to supply most power required at the load, and the other is to the inverter for variable frequency and/or magnitude of voltage. The conventional induction motor is operated under single excitation mode only, that is called induction mode. But in multi-excited induction motor both the induction mode and the synchronous mode are possible, and the proposed multi-excited induction motor can be driven as a synchronous motor by the extra three-phase input. At the synchronous mode the efficiency is improved so higher than that at induction mode or conventional induction motor. The rating of the inverter used for speed control of numberous electric equipment system can be reduced upto one-tenth of that for conventional induction motor. Also the cost and maintenance fee of multi-excited induction motor can be reduced compared to any other motor.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.529-531
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• 2008

Generation system using regenerative energy like photovoltaic, fuelcell is increased, PCS technology coming into the spotlight. The efficiency of DC-DC converter as part of the PCS is very important, multi-phase boost converter has more advantage than other topology. Input current of the multi-phase boost converter is divided into two inductor current because of parallel structure of the boost converters, thus it has features of decreasing input current ripple and output voltage ripple. Also multi-phase boost converter with soft switching can decrease switching loss using ZCS and ZVS. In this paper, simulation and experiment are performed to verify operation of the proposed converter, and efficiencies of the conventional and proposed converter are compared.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.87-87
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• 2000

In this paper, an integrated design of fault detection, diagnosis and reconfigurable control tot multi-input and multi-output system is proposed. It is based on the interacting multiple model estimation algorithm, which is one of the most cost-effective adaptive estimation techniques for systems involving structural and/or parametric changes. This research focuses on the method to recover the performance of a system with failed actuators by switching plant models and controllers appropriately. The proposed scheme is applied to a fault tolerant control design for flight control system.