• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.8
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• pp.805-815
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• 1992

In this paper, robust decoupling control scheme of miftivarlable systems Is studied. Design methods for Input-Output decoupling systems with robustness against signal failure In arbitrary feedback loop or actuator loop Is suggested based on the Riccati type matrix equation and state feedback, and is simulated In Turbo-Generator systems with B-Input, 2 output. The results of simulation represents the decoupled and stable response against the failure of signal In sensor or actuator loop. However, the system designed by conventional ,it ate feedback shows the unstable response. This method Is applied for robust decoupling control of the complicated multivariable systems.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.6
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• pp.719-726
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• 1999

본 논문은 교통 신호 제어 알고리즘들의 성능을 비교하기 위한 복합교차로 시뮬레이터를 구현하였다. 기존의 교통 시뮬레이터들은 단일교차로를 대상으로 하거나 텍스트 모드로 동작하는 경우가 많았다. 논문의 시뮬레이터는 Visual C++의 MFC 라이브러리를 사용하여 n $\times$ n 형태를 갖는 복합교차로에 적합하도록 객체지향적으로 구현되었으며, 성능 비교를 위하여 제어 알고리즘들을 별개의 윈도우에서 처리하기 쉽도록 MDI 방식을 사용하였다. 개발한 시뮬레이터는 그래프 윈도우와 맵 윈도우의 편리한 사용자 인터페이스, 논리시간 설정을 통한 다목적 시뮬레이션, 다양한 성능평가 출력 등의 특징을 갖는다. Abstract In this paper, we implemented a multiple crossroad simulator to evaluate the performance of the traffic signal control algorithms. Most of existing traffic simulators were operated in text-mode or at a single intersection. We developed the object-oriented simulator suitable for multiple crossroads with n $\times$ n intersections by using MFC (Microsoft Foundation Class) library in Visual C++. The simulator was implemented by using MDI (Multiple Document Interface) scheme in order to process both control algorithms in separate windows respectively. Our simulator has the following features: user friendly interface with graph window and map window, multi-purpose simulations by setting logical time, and various forms of performance evaluation.

• The Transactions of the Korea Information Processing Society
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• v.7 no.4
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• pp.1236-1245
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• 2000

This paper propose a novel scheme, called Mobiel Terminal Initiated Scheme(MTIS), in which mobile terminal initiates the backward handover by sending handover request message with the list of target radio ports. In this scheme, the old ATM switch suporting end-user mobility, denoted by EMAS\ulcorner, checks whether each EMAS\ulcorner, managing the target radio port, has its available resources. If it has, the EMAS\ulcorner performs the path rerouting between CrossOver Switch (COS) and itself after deciding the most suitable target radio port. Therefore, the MT initiates the handover after deciding the most suitable target radio port through the beacon signal of Wireless Access Point (WAP). The EMAS\ulcorner have only to check the resource availability of the target radio port. It is no need to waste time to decide the suitable target radio port. Also, once receiving the request of the resource availability, the EMAS\ulcorner can reduce the rerouting delay time due to perform the path rerouting to the COS. In comparison with that of the ATM-Forum procedure, our proposed MTIS handover delay time reduced 14~21%, and end-to-end transfer delay time reduced 2~9%, as a result of the simulation.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.5
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• pp.423-430
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• 2012

An adaptive maximum power point tracking (MPPT) scheme employing a variable scaling factor is presented. A MPPT control loop was constructed analytically and the magnitude variation in the MPPT loop gain according to the operating point of the PV array was identified due to the nonlinear characteristics of the PV array output. To make the crossover frequency of the MPPT loop gain consistent, the variable scaling factor was determined using an approximate curve-fitted polynomial equation about linear expression of the error. Therefore, a desirable dynamic response and the stability of the MPPT scheme were maintained across the entire MPPT voltage range. The simulation and experimental results obtained from a 3 KW rated prototype demonstrated the effectiveness of the proposed MPPT scheme.

• Proceedings of the KIPE Conference
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• 1996.06a
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• pp.85-88
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• 1996

New power factor correction(PFC) technique based on the averaged model of boost converter is proposed. Without measurement of input current, power factor correction scheme derived from the averaged model is presented. With the measurements of input voltage and output voltage, the control signal is generated to make the shape of the line current same as the input voltage. The characteristics of input line current distortion is analyzed by considering the generation of duty cycle.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.718-723
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• 1993

In this paper, we propose a neural network with fuzzy preprocessor not only for improving the classification accuracy but also for being able to classify objects whose attribute values do not have clear boundaries. The fuzzy input signal representation scheme is included as a preprocessing module. It transforms imprecise input in linguistic form and precisely stated numerical input into multidimensional numerical values. The transformed input is processed in the postprocessing module. The experimental results indicate the superiority of the backpropagation network with fuzzy preprocessor in comparison to the conventional backpropagation network.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.3
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• pp.520-526
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• 2018

In this paper, considering the superposition transmission-based wireless cooperative multicast communication system (ST-CMS) with multiple relays and destinations, we propose a relay selection scheme to improve the data rate of multicast communication. In addition, we adopt the optimal power allocation coefficient for the superposition transmission to maximize the data rate of the proposed relay selection scheme. To propose the relay selection scheme, we derive an approximate expression for the data rate of the ST-CMS, and present the relay selection scheme using only partial channel state information based on the approximate expression. Moreover, we derive an approximate average data rate of the proposed relay selection scheme. Through numerical investigation, comparing the average data rates of the proposed relay selection scheme and the optimal relay selection scheme using full channel state information, we show that the proposed scheme provides extremely similar performance to the optimal scheme in the high signal-to-noise power ratio region.

• The Journal of the Acoustical Society of Korea
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• v.27 no.7
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• pp.386-393
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• 2008

This paper proposes a new approach for speech enhancement in highly nonstationary noisy environments. The spectral subtraction (SS) is a well known technique for speech enhancement in stationary noisy environments. However, in real world, noise is mostly nonstationary. The proposed method uses an auto control parameter for an adaptive threshold to work well in highly nonstationary noisy environments. Especially, the auto control parameter is affected by a linear function associated with an a posteriori signal to noise ratio (SNR) according to the increase or the decrease of the noise level. The proposed algorithm is combined with spectral subtraction (SS) using a hangover scheme (HO) for speech enhancement. The performances of the proposed method are evaluated ITU-T P.835 signal distortion (SIG) and the segment signal to-noise ratio (SNR) in various and highly nonstationary noisy environments and is superior to that of conventional spectral subtraction (SS) using a hangover (HO) and SS using a minimum statistics (MS) methods.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.1104-1110
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• 1999

When a FM-CW radar is used to measure the target distance, the nonlinearity relationship between the VCO control voltage and the output frequency makes an adverse effect on the measurement accuracy. Recently, many nonlinearity correction schemes using signal processing techniques and dedicated hardwares have been studied. This paper presents a signal processing technique to compensate for the VCO nonlinearity using a reference signal. To demonstrate the validity of the presented technique, several experiments were conducted and the results show reduction of the distortion in the range profile and the resolution improvement.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.2
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• pp.88-95
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• 1996

It is inevitable for local systems to have deviations which represent interactions and modeling errors originated from the decomposition process of a large scale system. This paper presents a decentralized control scheme for interconnected systems using local linear models and a neuro-coordinator. In the proposed method, the local system is composed of a linear model and unknown deviations caused by linearizing the subsystems around operating points or by estimating parameters of the subsystems. Because the local system has unmeasurable deviations we define a local reference model which consists of a local linear model and a neural network to estimate the deviations indirectly. The reference model is reformed into a linear model which has no deviations through a transformation of input variables and we obtain an optimum feedback control law which minimizes a local performance index. Finally, we derive a decentralized feedback control law which consists of local linear states and neural network outputs. In the decentralized control, the neuro-coordinator generates a corrective control signal to cancel the effect of deviations through backpropagation learning with the errors obtained from the differences of the local system outputs and reference model outputs. Also, the stability of local system is proved by the degree of learning of the neural network under an assumption on a neural network learning index. It is shown by computer simulations that the proposed control scheme can be applied successfully to the control of a biased two-link planar robot manipulator.