• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.04a
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• pp.231-238
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• 1999

The longitudinal dynamic behaviors of the bridge system consisting of multiple simply supported spans under seismic excitations are examined considering pounding effects. The pounding phenomena between adjacent girders which may consequently result in the span collapses are modeled by using the multi-degree-of-freedom system, The inelastic behavior of the RC pier is also considered by adopting the hysteresis loop model and the p-$\delta$ effect. Motions of the foundation and abutment are also considered but the local damage resulting from the girder pounding assumed to be neligible. The developed model is found to give the appropriate information of the dynamic characteristics of the bridge behavior. It is observed that the pounding effect becomes significant as the peak acceleration of the seismic excitation increases. Under minor earthquakes the pounding tends to increase the relative displacements while under strong earthquakes it tends to decrease the relative displacements by restricting the longitudinal girder motions, therefore it is suggested that the pounding effects should be considered in the analysis of the relative displacements of the longitudinally adjacent girder motions.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2003.06a
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• pp.141-144
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• 2003

This paper proposes a design method of a CDBC(Continuous-time Deadbeat Controller)system that takes into account the response between the sampling instant and using second-order smoothing elements. The continuous deadbeat controller is composed of a serial integral compensator and a local feedback compensator introduced into the state feedback loop. A DC servo motor is chosen for implementing CDBC algorithm. Especially according to the variable input and disturbance, corresponding CDBC design method is suggested. A Matlab Simulink is used for simulation with the Motor parameter. By computer simulations, control inputs and system outputs are shown to have desirable property such as smoothness.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.1
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• pp.67-73
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• 2002

This paper presents a new design method of optimal continuous deadbeat controller by using second-order smoothing elements. The continuous deadbeat controller is made of a serial integral compensator and a local feedback compensator introduced into the state feedback loop. The decision method of the damping factor and the natural angular frequency of the smoothing element is described. A numerical example is given to show how well input-output characteristics are improved. Especially according to the variable input and disturbance, corresponding CDBC design method is suggested. By computer simulations, control inputs and system outputs are shown to have desirable property such as smoothness.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.215-218
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• 2015

Simultaneous laser ignition and spectroscopy is a scheme that enables rapid determination of the local equivalence ratio and condensed fuel concentration during a reaction in a two phase spray flame. We have conducted quantitative analysis of the LIBS signals according to the equivalence ratio, droplet size, droplet number density and droplet concentration as a part of novel feedback control strategy proposed for flame ignition and stabilization with simultaneous in situ combustion flow diagnostics. This is a desirable scheme since such real time information onboard an engine for instance can be constantly monitored and fed back to the control loop to enhance the mixing process and minimize emissions of unwanted species and potential combustion instability.

• Journal of Korea Society of Digital Industry and Information Management
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• v.4 no.3
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• pp.69-75
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• 2008

The objective of this paper is to increase the performance by selecting the optimal value in outputs of two algorithms that are Generlized-Lagrange and LMS(Least Mean Square). This paper presents superior performance by mixed two of conventional algorithm arbitrary. Based on the analysis from various simulation, it is observed that proposed method is better performance in terms of practical WLL(Wireless Local Loop) environment.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.806-808
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• 1993

New soft recovery drive which can alleviate the loss due to reverse recovery of diode is proposed. By using this drive, the reverse current of the diode is minimized and stabilized because there is inner local feedback loop between the turn-on current of the power MOSFET and the reverse recovery current of the diode. The loss and EMI noise can be considerably reduced in this way. Brief operational principle and experimental results are included to verify the usefulness.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06a
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• pp.836-841
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• 1994

This paper describes the global vibro-acoustic troubleshooting approach, used to identify and separate different sources of noise and vibrations on a boilerfeed pump testrig. The pump serves for rotor dynamic research of a EC-funded BRITE-Euram profect. This approach resulted in the identification of local structural flexibilities in the connections between the machinery and the base plate. The relative importance of the modes during normal operation is revealed by comparison with operational deformation shapes. The use of sound intensity mapping allowed to calculate the total sound power and to rank the equipment according to its sound power contribution. High acoustic levels were found and related to the fluid drive and to the piping system. Modification of the piping section resulted in a reduction of noise and vibration levels along the test loop and smooth operation in a wide suction pressure range.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.41.3-41
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• 2001

In this paper, we present a decentralized adaptive neural net(NN) controller for the transient stability and voltage regulation of a multimachine power system. First, an adaptively input-output linearizing controller using NN is designed to eliminate the nonlinearities and interactions between generators. Then, a robust control term which bounds terminal voltage to a neighborhood of the operating point within the desired value is introduced using only local information. In addition, we consider input saturation which exists in the SCR amplifier and prove that the stability of the overall closed-loop system is maintained regardless of the input saturation. The design procedure is tested on a two machine infinite bus power system.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.5
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• pp.334-341
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• 2019

This study proposes the control strategy for the seamless mode transfer of indirect current controlled parallel grid-connected inverters. Under the abnormal grid condition, the grid-connected inverter can convert the operation mode from grid-connected to stand-alone mode to supply power to the local load. For a seamless mode transfer, the time delay problems caused by the accumulated control variable error must be solved, and the indirect current control method has been applied as one of the solutions. In this study, the design of control parameters for the proportional-resonant-based triple-loop indirect current controller and the control strategy for the seamless mode transfer of parallel grid-connected inverters are described and analyzed. The validity of the proposed mode transfer method is verified by the PSiM simulation results.

• International journal of advanced smart convergence
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• v.10 no.2
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• pp.175-186
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• 2021

We have studied the speed regulation of the permanent magnet synchronous motor (PMSM) servo system in this paper. To optimize the PMSM servo system's speed-control performance with disturbances, a non-linear speed-control technique using a back-propagation neural network (BP-NN) algorithm forthe controller design of the PMSM speed loop is introduced. To solve the slow convergence speed and easy to fall into the local minimum problem of BP-NN, we develope an improved BP-NN control algorithm by limiting the range of neural network outputs of the proportional coefficient Kp, integral coefficient Ki of the controller, and add adaptive gain factor β, that is the internal gain correction ratio. Compared with the conventional PI control method, our improved BP-NN control algorithm makes the settling time faster without static error, overshoot or oscillation. Simulation comparisons have been made for our improved BP-NN control method and the conventional PI control method to verify the proposed method's effectiveness.