• 한국정밀공학회지
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• 제15권4호
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• pp.83-90
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• 1998

In this paper, we present neural network for control of Left Ventricular Assist Device(LVAD) system with a pneumatically driven mock circulation system. Beat rate(BR), Systole-Diastole Rate(SDR) and flow rate are collected as the main variables of the LVAD system. System modeling is completed using the neural network with input variables(BR, SBR, their derivatives, actual flow) and output variable(actual flow). It is necessary to apply high perfomance control techniques, since the LVAD system represent nonlinear and time-varing characteristics. Fortunately. the neural network can be applied to control of a nonlinear dynamic system by learning capability In this study, we identify the LVAD system with neural network and control the LVAD system by PID controller and neural network feedforward controller. The ability and effectiveness of controlling the LVAD system using the proposed algorithm will be demonstrated by experiment.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권10호
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• pp.579-586
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• 1999

This paper describes a simulation model and a scaled hardware model to analyze the dynamic performance of Unified Power Flow Controller, which can flexibly adjust the active power flow through the ac transmission line. The design of control system for UPFC was developed using vector control method. The results of simulation and scaled hardware test show that the developed control system works accurately. Both models would be very effective for analyzing the dynamic performance of the Unified Power Flow Controller.

• ETRI Journal
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• 제45권4호
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• pp.615-626
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• 2023

Under limited transmission conditions, many factors affect the efficiency of video transmission. During the flight of an unmanned aerial vehicle (UAV), frequent network switching often occurs, and the channel transmission condition changes rapidly, resulting in low-video transmission efficiency. This paper presents an efficient video coding flow for UAVs working in the 5G nonstandalone network and proposes two bit controllers, including time and spatial bit controllers, in the flow. When the environment fluctuates significantly, the time bit controller adjusts the depth of the recursive codec to reduce the error propagation caused by excessive network inference. The spatial bit controller combines the spatial bit mask with the channel quality multiplier to adjust the bit allocation in space to allocate resources better and improve the efficiency of information carrying. In the spatial bit controller, a flexible mini graph is proposed to compute the channel quality multiplier. In this study, two bit controllers with end-to-end codec were combined, thereby constructing an efficient video coding flow. Many experiments have been performed in various environments. Concerning the multi-scale structural similarity index and peak signal-to-noise ratio, the performance of the coding flow is close to that of H.265 in the low bits per pixel area. With an increase in bits per pixel, the saturation bottleneck of the coding flow is at the same level as that of H.264.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권1호
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• pp.1-17
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• 2016

The separated management and operation of commercial IP/optical multilayer networks makes network operators look for a unified control plane (UCP) to reduce their capital and operational expenditure. Software-defined networking (SDN) provides a central control plane with a programmable mechanism, regarded as a promising UCP for future optical networks. The general control and scheduling mechanism in SDN-based optical burst switching (OBS) networks is insufficient so the controller has to process a large number of messages per second, resulting in low network resource utilization. In view of this, this paper presents the burst-flow scheduling mechanism (BFSM) with a proposed scheduling algorithm considering channel usage. The simulation results show that, compared with the general control and scheduling mechanism, BFSM provides higher resource utilization and controller performance for the SDN-based OBS network in terms of burst loss rate, the number of messages to which the controller responds, and the average latency of the controller to process a message.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.1124-1126
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• 1997

The Unified Power Flow Controller(UPFC) with a series inverter and a shunt inverter ia able to control all three line Parameters(voltage, impedance and phase angle) and so UPFC technology has the potential to enhance the implementation and broad application of the FACTS concept with improved Performance. In this Paper, the UPFC is applied in order to improve the power flow oscillation damping. The modal performance measure is minimized in order to determine the optimal parameters of UPFC controller for damping Power flow oscillations. The dynamics of the injected voltage of UPFC is represented as a first order delay element. The UPFC controller used here is of the PIO type and the input signal to the controller is the active power flow through the UPFC. The effect of UPFC application to the Power system are analyzed from the stand point of power system oscillation damping.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1007-1011
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• 2003

In this paper, a design of I-PDA controller by CDM to control a flow process whose structure is first order lag plus a dead time is introduced. The factor of dead time of the process is approximated by second order Pade approximation in order to get a third order system. The simulations show that both of the transient and steady state specifications can be fulfilled. However, the transient response of the I-PDA control system still has long rise time. Then, a feedforward controller (FFC) with two adjustable parameters and one derivative time is introduced into I-PDA control system for improving the speed of the system response. It is shown, from the simulation results, that the performance of the I-PDA control system with suitable FFC has shorter rise time and no overshoot, while settling time remains almost the same. The performance comparison of the proposed control system with the PI control system with and without FFC is also made.

• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.478-489
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• 2013

The controllability and stability of power systems can be increased by Flexible AC Transmission Devices (FACTs). One of the FACTs devices is Interline Power-Flow Controller (IPFC) by which the voltage stability, dynamic stability and transient stability of power systems can be improved. In the present paper, the convenient operation and control of IPFC for transient stability improvement are considered. Considering that the system's Lyapunov energy function is a relevant tool to study the stability affair. IPFC energy function optimization has been used in order to access the maximum of transient stability margin. In order to control IPFC, a Brain Emotional Learning Based Intelligent Controller (BELBIC) and PI controller have been used. The utilization of the new controller is based on the emotion-processing mechanism in the brain and is essentially an action selection, which is based on sensory inputs and emotional cues. This intelligent control is based on the limbic system of the mammalian brain. Simulation confirms the ability of BELBIC controller compared with conventional PI controller. The designing results have been studied by the simulation of a single-machine system with infinite bus (SMIB) and another standard 9-buses system (Anderson and Fouad, 1977).

• 한국항공운항학회지
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• 제22권1호
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• pp.1-6
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• 2014

In this paper, controller propose to prevent compressor surge and improve the transient response of the fuel flow control system of turbojet engine. Turbojet engine controller is designed by applying Artificial Neural Network PID control algorithm and make an inference by applying Levenberg-Marquartdt Error Back Propagation Algorithm. Artificial Neural Network inference results are used as the fuel flow control inputs to prevent compressor surge and flame-out for turbojet engine for UAV. High Gain Observer is used to estimate to compressor rotation speed of turbojet engine. Using MATLAB to perform computer simulations verified the performance of the proposed controller. Response characteristics pursuant to the gain were analyzed by simulation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.154-161
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• 2000

As a mass flow controller is widely used in many manufacturing processes for controlling a mass flow rate of gas with accuracy of 1%, several investigators have tried to describe the heat transfer phenomena in a sensor tube of an MFC. They suggested a few analytic solutions and numerical models based on simple assumptions, which are physically unrealistic. In the present work, the heat transfer phenomena in the sensor tube of the MFC are studied by using both experimental and numerical methods. The numerical model is introduced to estimate the temperature profile in the sensor tube as well as in the gas stream. In the numerical model, the conjugate heat transfer problem comprising the tube wall and the gas stream is analyzed to fully understand the heat transfer interaction between the sensor tube and the fluid stream using a single domain approach. This numerical model is further verified by experimental investigation. In order to describe the transport of heat energy in both the flow region and the sensor tube, the Nusselt number at the interface between the tube wall and the gas stream as well as heatlines is presented from the numerical solution.

• 대한기계학회논문집B
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• 제33권8호
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• pp.573-579
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• 2009

A thermal mass air flow sensor, which consists of a micro-heater and thermal sensors on the silicon-nitride thin membrane structure, is micro-fabricated by MEMS processes. Three thermo-resistive sensors, one for the measurement of microheater temperature, the others for the measurement of membrane temperature upstream and downstream of the micro-heater respectively, are used. The micro-heater is operated under the constant temperature difference mode via a real time controller, based on inlet air temperature. Two design models for microfabricated flow sensor are compared with experimental results and confirmed their applicabilities and limitations. The thermal characteristics are measured to find the best flow indicator. It is found that two normalized temperature indicators can be adopted with some advantages in practice. The flow sensor with this control mode can be adopted for wide capability of high speed and sensitivity in the very low and medium velocity ranges.