• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.198-203
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• 2001

In this paper, a new predictive control algorithm considering the parameters of series active filter has been proposed to improve the performance. By using the proposed control scheme, the current ripple drastically reduced and an improved steady state performance can be obtained. The proposed method has another advantage in the size. and cost by excluding additional passive fitters. The validity of the proposed method will be proved by the computer simulation.

• International Journal of Aeronautical and Space Sciences
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• v.12 no.1
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• pp.16-23
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• 2011

In this paper, nonlinear model predictive control (NMPC) is addressed to develop formation guidance for multiple unmanned aerial vehicles. An NMPC algorithm predicts the behavior of a system over a receding time horizon, and the NMPC generates the optimal control commands for the horizon. The first input command is, then, applied to the system and this procedure repeats at each time step. The input constraint and state constraint for formation flight and inter-collision avoidance are considered in the proposed NMPC framework. The performance of NMPC for formation guidance critically degrades when there exists a communication failure. In order to address this problem, the modified optimal guidance law using only line-of-sight, relative distance, and own motion information is presented. If this information can be measured or estimated, the proposed formation guidance is sustainable with the communication failure. The performance of this approach is validated by numerical simulations.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.4
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• pp.757-766
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• 2017

For implementing the proportional navigation guidance law on passive homing missiles equipped with strapdown imaging infrared seekers, the line-of-sight angles and rates with respect to the inertial frame should be estimated by carefully handling the parasitic instability effect due to the seeker's latency. By introducing a new state vector representation along with the Pade approximation for compensating the time-delay of the seeker, this paper proposes a new guidance filter structure, stochastic dynamic models and measurement equations, in three-dimensional homing problem. Then, it derives the line-of-sight angle and rate estimator in general two-dimensional engagement by applying the extended Kalman filter to the proposed structure. The estimation performance and the characteristics of the proposed filter were evaluated via a series of numerical experiments.

• Journal of information and communication convergence engineering
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• v.15 no.1
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• pp.14-20
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• 2017

In this paper, we discuss physical layer security techniques in downlink networks, including eavesdroppers. The main objective of using physical layer security is delivering a perfectly secure message from a transmitter to an intended receiver in the presence of passive or active eavesdroppers who are trying to wiretap the information or disturb the network stability. In downlink networks, based on the random feature of channels to terminals, opportunistic user scheduling can be exploited as an additional tool for enhancing physical layer security. We introduce user scheduling strategies and discuss the corresponding performances according to different levels of channel state information (CSI) at the base station (BS). We show that the availability of CSI of eavesdroppers significantly affects not only the beamforming strategy but also the user scheduling. Eventually, we provide intuitive information on the effect of CSI on the secrecy performance by considering three scenarios: perfect, imperfect, and absence of eavesdropper's CSI at the BS.

• Journal of Power Electronics
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• v.14 no.6
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• pp.1189-1196
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• 2014

A modular multilevel-clamped composited multilevel converter ($M-MC^2$) is proposed. $M-MC^2$ enables topology reconfiguration, power device reuse, and composited clamping. An advanced five-level converter ($5L-M-MC^2$) is derived from the concept of $M-MC^2$. $5L-M-MC^2$ integrates dual three-level T-type modules and one three-level neutral point clamped module. This converter can also integrate dual three-level T-type modules and one passive diode module by utilizing the device reuse scheme. The operation principle and SPWM modulation are discussed to highlight converter performance. The proposed $M-MC^2$ is comprehensively compared with state-of-the-art five-level converters. Finally, simulations and experimental results are presented to validate the effectiveness of the main contributions of this study.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.871-875
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• 1996

The Output feedback linear quadratic regulator control is applied to the design of active suspension system using 7 DOF full car model. The performance index reflects the vehicle vertical movement, pitch and roll motion, and minimization of suspension stroke displacements in the rattle space. The elements of gain matrix are approximately decoupled so that each suspension requires only local information to generate the control force. The simulation results indicates that the output feedback LQ controller is more effective than purely passive or full state feedback active LQ controllers in following the road profile at the low frequency range and suppressing the road disturbance at the high frequency ranges.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2687-2689
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• 2004

LMI(Linear Matrix Inequalities) technique is implemented to control hybrid bio system with electric element Biological materials such as muscle and tissue are modeled as electrically passive element in the system. State feedback controller for the hybrid system is designed with constrained control input. The hybrid bio electrical system is characterized in terms of the time and frequency.

• Journal of Ocean Engineering and Technology
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• v.7 no.2
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• pp.37-43
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• 1993

The simplest vibrtion absorber is the impact damper which consists of a small mass allowed to impact between two gaps sp that energy is dissipated by conversion into noise and heat. Impact damping is a passive vibration control technique to attenuate the vibrations of lightly damped. It has been investigated to reduce the excessive vibrations of turbin blades, radar antennas, machine tools and tall light poles. In this paper, the efficiency of impact vibration absorber was investigated. A steady state vibration of two equispaced impacts per cycle was assumed. The analysis based on the assumption has been considered and the theory is examined experimentally.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.7
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• pp.524-531
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• 2003

This paper presents an active vibration control of a flexible beam structure using a hybrid mount which consists of elastic rubber and Piezoelectric material. After identifying stiffness and damping properties of the rubber and piezoelectric elements, a mechanical model of the hybrid mount is established. The mount model is then Incorporated into the beam structure, and the governing equation of motion is obtained in a state space. A sliding mode controller is designed in order to actively attenuate the vibration of the beam structure subjected to high frequency and small magnitude excitations. The controller is experimentally realized and control responses such as acceleration of the beam structure and force transmission through the hybrid mount are evaluated. In addition. a comparative work is done between the passive and hybrid mount systems.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.330-333
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• 2002

The design of high power electronic circuits and the verification of the design by practical experiments are time and cost consuming. Recently power circuit simulation technique is developing to do it easily. However, most of the simulation has used the ideal switch model consists of passive component that can not describe the physical characteristics of semiconductor devices and cannot describe the switching transient state. For the design of such power electronic circuits by the simulation, the switching transients are very important. Therefore the simulation models must describe the switching transient and the stationary behavior as precisely as possible on the hand and as fast as possible the other hand. This paper introduces the application of the physical models of power devices that are developed by TUM(Technical University of Munich, Germany) for the power electronic circuit analysis.