• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.835-840
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• 2011

In this study, a disk-type piezoelectric transformer was fabricated. Its diameter was 50 mm and thickness was 4.5 mm. The driving and generating electrode with their gap of 1mm were fabricated on the top surface. But the common electrode was fabricated on the whole bottom surface. The electrode surface of driving and generating part on the top surface was divided into 2, 4 and 8 pieces. The electrical characteristics with its electrode variation was measured in the range of load resistance of $100{\Omega}{\sim}10_{K\Omega}$. We investigated quantitively the influence of the set-up voltage ratio.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.6 no.6
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• pp.32-41
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• 1992

In this paper, an advanced Pulse Width Modulation Inverter strategy for driving a variable-speed induction motor is introduced. A switching pattern making use of the near-proportionality of voltage and frequency in AC machines operating with constant flux was computed. At low magnitudes and ow frequencies of the fundamental, many more harmonics are eliminated than at high magnitudes and frequencies. In order to keep the inverter switching frequency constant over the output frequency range, the chopping frequency is diminished as the frequency of the fundamental increases. Using these modulation strategy, the harmonics components of PWM inverter are efficiently eliminated.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.731-735
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• 1993

When induction motor is driven with a load commutated inverter, the output part of the inverter must be capacitive. But, in order to be a good load commutation at the low speed range, very large capacitor or force commutated circuit must be used regarding the capacity of motor. This paper proposed the force commutated circuit for driving the motor in case of the installation of capacitor which can be capable of load commutation at the rating speed. The force commutated circuit is operated by the LC resonant circuit, auxiliary source and SCR, and also composed of the commutation circuit which control the interval of the inverse voltage across the inverter.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.179-181
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• 1998

In this paper, one chip PWM pattern generator which eliminates time delay of computations and improves utilization factor of voltage is proposed. Both amplitude of sinusoidal signal and triangular signal are directly controlled. Thus, time delay of computations can be eliminated, and it is possible to track accurately instantaneous current for a sudden change of load with microprocessor 80C196KC. In addition, setting dead-time is also possible for wide range. From experimental work with inverter system for driving induction motor, the validity of proposed one chip PWM pattern generator is verified.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.3 s.96
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• pp.128-135
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• 1999

A driving simulators of aircraft and vehicle may consist of hydraulic power systems with many single-rod cylinders. The single-rod hydraulic systems are convenient but need more robust control scheme in order to achieve a reliable performance against the wide range of operating disturbances and the inherent model uncertainties. $H_{\infty}$ control scheme was implemented to the 2 degree-of-freedom hydraulic device similar to the simple driving simulator. With the reasonable disturbances from sensor, base and pump and also with the linearization of model, the simulation and experimental results showed good agreements.

• IEMEK Journal of Embedded Systems and Applications
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• v.17 no.2
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• pp.109-114
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• 2022

This paper proposes a 2D joystick and LoRa-based teleoperation system for the Ackermman steering mobile robot. The proposed joystick mapping algorithm reduces the linear speed of the robot when the joystick is steered in the direction of the maximum steering angle in the high-speed driving state of a mobile robot to reduce the risk of rollover. The LoRa-based remote operation system is designed for remote operation of mobile robots that require long range communication with relatively little data transmission and low power. The proposed system is implemented and the experimental results demonstrate the effectiveness of the teleoperation system with respect to the stability of communication strength and the robot motion.

• Progress in Superconductivity and Cryogenics
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• v.11 no.2
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• pp.20-24
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• 2009

In order to explain the operating characteristics of LTMFP in a wide range of driving frequency, an analytical equation that takes into account the detailed behavior of the normal spot is necessary. In this paper, based on the phenomenon of magnetic diffusion of the superconductor we modified the theoretical equations for pumping action in LTMFP. The modified equations explained well the pumping actions under the different load magnets. These results are important to explain the pumping tendency of the LTMFP according to driving frequency.

• Journal of Auto-vehicle Safety Association
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• v.15 no.4
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• pp.23-31
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• 2023

In recent years, the technology for autonomous driving has been advancing rapidly, ADAS (Advanced Driver Assistance System) functions, which improve driver convenience and safety performance, are mostly equipped in recently released vehicles and range from level 0 to level 2 in autonomous driving technology. Among the various functions of ADAS, AEBS (Autonomous Emergency Braking System), which analyzes traffic accidents, is the most closely related to the vehicle's braking. This study developed a simulation technique for reproducing accidents related to AEBS based on real vehicle experimental data, and it was applied to the analysis of actual ADAS vehicle accidents to identify the causes of accidents.

• Journal of Power Electronics
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• v.15 no.5
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• pp.1402-1408
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• 2015

A MOSFET's gate driver based on magnetic coupling is investigated. The gate driver can meet the demands in applications for wide range of duty cycles and high frequency. Fully galvanic isolation can be realized, and no auxiliary supply is needed. The driver is insensitive to the leakage inductor of the isolated transformer. No gate resistor is needed to damp the oscillation, and thus the peak output current of the gate driver can be improved. Design of the driving transformer can also be made more flexible, which helps to improve the isolation voltage between the power stage and the control electronics, and aids to enhance the electromagnetic compatibility. The driver's operation principle is analyzed, and the design method for its key parameters is presented. The performance analysis is validated via experiment. The disadvantages of the traditional magnetic coupling and optical coupling have been conquered through the investigated circuit.

• Current Optics and Photonics
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• v.5 no.4
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• pp.466-476
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• 2021

Frequency-multiplication technology based on microwave photonic principles can be used to generate microwave and millimeter wave signals with a wide frequency tuning range. However, the existing cascaded external modulation frequency-tupling scheme needs to ensure the phase coherence of the modulated Radio Frequency (RF) signal, while the phase modulation directly limits the frequency tuning range of the external modulation frequency multiplication. In this paper, a novel approach for generating an incoherent frequency 12-tupling signal with cascade modulation is proposed. The structure of cascaded dual-parallel Mach-Zehnder modulators can generate a frequency 12-tupling signal. The proposed structure uses no filter or phase control of the RF driving signal. Microwave photonic frequency-tupling was realized under incoherent conditions. Software simulations and experiments validated the proposed structure and proved that it can generate frequency 12-tupling microwave signals under incoherent conditions. Both the frequency range and reliability of the frequency-tupling system has been improved by the proposed structure.