• Journal of Power Electronics
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• v.11 no.3
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• pp.271-278
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• 2011

This paper presents a LLC resonant controller IC for secondary side control without external active devices to achieve low profile and low cost LED back light units. A gate driving transformer is adopted to isolate the primary side and the secondary side instead of an opto-coupler. A new integrated dimming circuitry is proposed to improve the dynamic current control characteristic and the current density of a LED for the brightness modulation of a large screen LCD. A dual-slope clock generator is proposed to overcome the frequency error due to the under shoot in conventional approaches. This chip is fabricated using 0.35 ${\mu}m$ BCD technology and the die size is $2{\times}2\;mm^2$. The frequency range of the clock generator is from 50 kHz to 500 kHz and the range of the dead time is from 50 ns to 2.2 ${\mu}s$. The efficiency of the LED driving circuit is 97 % and the current consumption is 40 mA for a 100 kHz operation frequency from a 15 V supply voltage.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.1
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• pp.9-16
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• 1997

The method of designing robust two degree of freedom(2 DOF) controllers for linear systems with parameter uncertainties and unmodeled dynamics is presented in this paper. Robust performance condition that accounts for robust model matching of closed loop system and disturbance rejection is derived. Using the robust performance condition, the feedback controller is designed to meet robust stability and disturbance rejection specifications, while prefilter is used to improve the robust model matching properties. The $H^{\infty}$ and $\mu$ controller for six degree of freedom vehicle with parameter variations are designed and compared. Simulations for hydrodynamic parameter variations and disturbance are presented to demonstrate the achievement of good robust performance.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.884-886
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• 1998

This paper presents an LQG based robust TCSC supplementary controller design to suppress the SSR in the FACTS. This controller is designed to have the robust stability against the plant model uncertainty. The robust stability is guaranteed using the $\mu$ analysis. Time domain simulations using a nonlinear system model show that the proposed TCSC supplementary controller can suppress the SSR efficiently against the plant model uncertainty.

• Journal of Power Electronics
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• v.14 no.4
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• pp.796-805
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• 2014

A digital controller with a low-power approach for point-of-load synchronous buck converters is discussed and compared with its analog counterpart to confirm its feasibility for system integration. The tri-mode digital controller IC in $0.35{\mu}m$ CMOS process is presented to demonstrate solutions that include a PID, quarter PID, and robust RST compensators. These compensators address the steady-state, stand-by, and transient modes according to the system operating point. An idle-tone free condition for ${\Sigma}-{\Delta}$ DPWM reduces the inherent tone noise under DC-excitation. Compared with that of the traditional approach, this condition generates a quasi-pure modulation signal. Experimental results verify the closed-loop performances and confirm the power-saving mechanism of the proposed controller.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.441-444
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• 1997

This paper describes the bending traveling-wave type ultrasonic motor which generates the traveling wave by combining two standing waves with phase difference time and space. In +2$0^{\circ}C$~3$0^{\circ}C$, the operation characteristic of USM has represented normal condition. But in the other temperature, the operation characteristic of USM has abnormal condition, that is driving frequency, drive current and r.p.m are down. The recent USM has controller without temperature compensation. This study aimed at fuzzy controller which must follow the frequency at operation temperature and then r.p.m and torque increased.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.8
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• pp.2958-2962
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• 2010

We developed a Microcurrent acupuncture point treatment equipment using micro-controller AVR. This equipment can generate a sine wave, triangle wave, square wave and DC. The frequency range of waves like the sine wave and the triangle wave is 1 - 320 Hz and the output range of DC is $40-200\;{\mu}A$. The duration is controllable between a minute to 30 minutes.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1839-1844
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• 2010

A power management controller circuit with switched capacitor mode down regulator and battery charger block for semi-active RFID tags was proposed and fabricated. The main purposes of the proposed switched capacitor mode down regulator and battery charger block are to reduce standby current and to provide a self-controlled thin film battery charger by detecting the received RF power, respectively. Fabricated chip area is $360,000{\mu}m^2$ and measured standby current was about $1.3{\mu}A$. To further reduction of standby current, a wake-up circuit has to be included in the power management controller.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.95.3-95
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• 2001

This paper investigates the simultaneous use of mixed H2/H_inf and mu-synthesis design methodology to design a robust controller for flexible link. We adopt four steps to design control system as follows: Step 1 : Generally, there are differences between the nominal and real model, so we consider the plant as a combination of parametric model uncertainty and unstructured uncertainty represents real structural uncertainties associated with the damping ratios of the flexible modes retained in the nominal model without payload. denotes the uncertainty which is due to the payload added at the tip. Step 2 : We adopt the mixed H2/H_inf theory to design a feedback controller K(s) by using the model uncertainty ...

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.6
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• pp.41-48
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• 2002

This study is on the structural control experiment for a small scale three-story building structure employing on active mass damper subjected to earthquake loading. $\mu$-synthesis controllers, which belong to robust control strategies, were designed and their performance were experimentally verified. Frequency-dependent weighting functions corresponding to disturbance input and controlled output were defined and combined to produce optimal $\mu$-synthesis controllers. The experiment result shows 60-70% reduction in RMS responses under the band-limited white noise excitation and 30-45% reduction in peak responses under the scaled earthquake excitations. Good agreement was obtained between the simulations based on the identified mathematical model and experimental results. And the simulations for the system with uncertainties show that the designed controllers are robust within a specified range of uncertainties.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.535-536
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• 2008

By reducing size of operation code, an improved MCU(micro controller unit) is implemented in this paper. The proposed MCU is developed for 32Bit Embedded System. The MCU has a general 32Bit MCU operations. The MCU supports to an ICE device.