• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.211-212
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• 1998

In this experiment, we developed a mind switching device which uses $\alpha$-wave with its amplitude varying between the eye-open and closed states. If the subject closes eyes, the switch toggles with a small delay. The circuit consists of an amplifier, a filter and a switch. An instrument amplifier is used fur high CMRR and for high input impedance. An 8th order Butterworth filter was able to reduce noise satisfactorily. The signal is then converted to a DC level, and finally a Schmitt trigger was used to generate a switching pulse.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.2
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• pp.167-172
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• 2007

In this paper, we analyzed the molecular behavior of IPS-LCDs and VA-LCDs by using numerical simulation. The numerical simulation was performed on the basis of Ericksen-Leslie continuum theory. To improve the accuracy of the calculation, we considered fluid balance equation and director balance equation at the same time. thus, we calculated the flow effect for both switching on and off states. As the results of simulation, we confirmed abnormal twist in IPS-LCDs and fast molecular behavior in VA-LCDs which could influence response time.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.6
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• pp.509-516
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• 2015

The overmodulation characteristics of a carrier-based medium vector pulse width modulation (CBMVPWM) are examined in this study. CBMVPWM can completely eliminate leakage currents in a three-phase, three-level inverter using only the switching states with the same common mode voltage even in an overmodulation operation. The analytic equations for the magnitude of the output voltage and the switching frequency are derived for overmodulation operation, and the effect of dead time on the leakage current is demonstrated. This study presents the operating principle of CBMVPWM, basic overmodulation features, and simulations and experiments for operating verification.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.600-603
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• 2009

The liquid crystal device with switchable dynamic mode and memory mode has been investigated and developed. The proposed device reveals splay, ${\pi}$ twist and bend states by selective switching among them. In the dynamic mode, this device is operated in the bend state which exhibits the wide view angle and fast response time properties due to the self-compensated bend structure and flow accelerated fast response time. In the memory mode, the permanent memory characteristics in the splay and ${\pi}$ twist sates are obtained, respectively. The switching mechanisms of the tristate device are also proposed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.205-209
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• 1999

This paper proposes a variable structure position controller for an induction motor(IM) which uses a reaching law and an integral compensating nonlinear switching function. With the reaching law, reaching mode can be established quantitatively during transient state so that dynamic control performance is improved. With the integral compensating nonlinear switching function, both very low overshoot and high steady state control accuracy can be obtained by compensating the states chattering problem due to the unmodelled dynamics of inverter and feedback sensors. For experiment a digital servo driver which consists of a DSP and an IPM inverter was developed. With the various experimental results, IM position control performance was verified.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.1
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• pp.89-97
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• 2003

High frequency common mode voltage produced by PWM inverter fed Induction motor is a major cause of conducted EMI, creation motor ground currents, bearing currents and other harmful products. The zero switching states of inverter control invoke large in comparison with the non-zero switching state of Inverter control. We proposed a common mode voltage reduction method based on sinusoidal PWM technique. PWM signal are generated by comparing respective sinusoidal reference signal with three triangular carrier wave displaced of 120$^{\circ}$. Simulation and experimenta1 result show that common mode voltages in the proposed PWM technique are reduced by approximate 66% more than conventional FWM technique.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.8 s.179
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• pp.1899-1909
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• 2000

This paper proposes a new $H_{\infty}$ yaw moment control scheme using brake torque switching for improving vehicle performance and stability especially in high speed driving. In the scheme, one wheel is selected, depending on the vehicle states, at which a brake torque for control is applied. Steering angles are modeled as a disturbance to the system and the $H_{\infty}$ controller is designed to minimize the difference between the performance of the vehicle and that of the desired model. Its performance robustness as well as stability robustness to system parameter variations is assured through ${\mu}$-analysis. Various simulations with a nonlinear 8-DOF vehicle model show that proposed controller enhances the vehicle performance and stability under disturbances and parameter variations as well as under the normal driving condition.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.9
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• pp.643-651
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• 2001

Fused vertical directional coupler switches (FVCSs) with switching operation induced section (SOIS) and extinction ratio enhanced section (ERES) are proposed. In these FVCSs, switching operation is achieved by changing the refractive indices of both cores in SOIS and improvement of extinction ratios larger than 30dB for both cross and bar states is achieved by controlling the asymmetry of refractive indices between both cores in ERES. In addition, the design guidelines to have high extinction ratios larger than 30dB with large tolerances of the refractive index of cores are presented.

• Journal of Power Electronics
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• v.15 no.4
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• pp.1006-1017
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• 2015

This paper presents a finite control set model predictive control (FCS-MPC) strategy for the AC/DC matrix converter used in grid-connected battery energy storage system (BESS). First, to control the grid current properly, the DC current is also included in the cost function because of input and output direct coupling. The DC current reference is generated based on the dynamic relationship of the two currents, so the grid current gains improved transient state performance. Furthermore, the steady state error is reduced by adding a closed-loop. Second, a Luenberger observer is adopted to detect the AC input voltage instead of sensors, so the cost is reduced and the reliability can be enhanced. Third, a switching state pre-selection method that only needs to evaluate half of the active switching states is presented, with the advantages of shorter calculation time, no high dv/dt at the DC terminal, and less switching loss. The robustness under grid voltage distortion and parameter sensibility are discussed as well. Simulation and experimental results confirm the good performance of the proposed scheme for battery charging and discharging control.

• Journal of Power Electronics
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• v.18 no.6
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• pp.1819-1829
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• 2018

A three-phase, three-switch, and three-level boost-type PWM rectifier (Vienna rectifier) is proposed as an active front-end power factor correction (PFC) rectifier for telecom loads. The proposed active front-end PFC rectifier system is modeled by the switching cycle average model. The relation between duty ratios and DC link capacitor voltages is derived in terms of the system input currents. Furthermore, the feasible switching states are identified and applied to the proposed system to reduce the switching stress and DC ripples. A detailed equivalent circuit analysis of the proposed front-end PFC rectifier is conducted, and its performance is verified through simulations in MATLAB. Simulation results are verified using an experimental setup of an active front-end PFC rectifier that was developed in the laboratory. Simulation and experimental results demonstrate the improved power quality parameters that are in accordance with the IEEE and IEC standards.