• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.2050-2051
• /
• 2007

As a fundamental investigation to develop a sensor which is able to detect shorted turn phenomenon of generator rotor, we have experimented with self-made sensor using flux generator and high-resolution oscilloscope. We have recorded sensor-induced voltage according to the different condition, such as variations of turn, diameter and length of sensor. Based on the acquired data, we analyzed and simulated under similar circumstances of actual spot to maximize reliability. We have a plan to invest more resources to supply power plants with the developed sensor for ourselves.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.11a
• /
• pp.129-131
• /
• 1999

Driving generator of USMs(ultrasonic motors) with low noise, high efficiency was designed and fabricated. It was focused on merits such as size-reduction, thermal resistance, To control revolution speed, input frequency was varied. Output of generator had frequency range of 39.1 ∼ 43.5 MHz and voltage of 120 V. USM with resonant frequency 40.3 kHz exhibited a maximum torque of 2.5 kg $.$ cm and a maximum revolution speed of about 130 rpm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2007.10a
• /
• pp.776-780
• /
• 2007

In this paper, the charge pump circuit of a VPP generator for a low voltage DRAM is newly proposed. The proposed charge pump is a 2-stage cross coupled charge pump circuit. The charge transfer efficiency is improved, and Distributed Clock Inverter is located in each charge pump stage to reduce clock period so that the pumping current is increased. In addition, the precharge circuit is located at Gate node of charge transfer transistor to solve the problem which is that the Gate node is maintained high voltage because the boosted charge can't discharge, so device reliability is decreased. The simulation result is that pumping current, pumping efficiency and power efficiency is improved. The layout of the proposed VPP generator is designed using $0.18{\mu}m$ Triple-Well process.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.6
• /
• pp.558-566
• /
• 2017

In this study, we developed an electron-emission OH radical generator for waste water treatment. The stability of the circuitry was ensured by implementing stable pulse waves with a MOSFET and reducing the momentary current rise. The OH radical generator uses a high-voltage and low-current discharger. The performance of the device was evaluated experimentally, which showed that it is possible to produce a stable and uniform pulse waveform for the drain current of the power MOSFET, which is connected to the input side of an AC multiplying converter through negative feedback circuitry with CR-snubber architecture. It was also possible to reduce the excitation current of the converter and improve the stability of the oscillation circuit. In addition, the generator can generate hydroxyl radicals stably. The bactericidal activities were also evaluated, and the germicidal power for E. coli, S. aureus, and S. flexneriwas improved by 99.9% or more after 60 minutes.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.53 no.11
• /
• pp.647-657
• /
• 2004

Helical magneto-cumulative generator(HMCG)s are very useful devices in suppling pulsed high current to inductance loads. To apply fast high voltage pulses to high impedance loads, high current outputs of HMCGs are required to be conditioned to higher voltages by using various pulse components such as opening/closing switches and pulse transformer. In this paper, stepping with the trends of requirements for ever-increasing energy in pulsed power applications coupling methods is investigated to obtain higher output energy by connecting several HMCGs in series or parallel way. The coil dimension of HMCGs used in series or parallel connections was 50 mm in diameter and 150 mm in length. The coil was fabricated by using enamel-coated copper wire of 1 mm in diameter. The highest energy amplification ratio and peak voltage of load were achieved from the serially connected four-barrel HMCG system. They were 68 and 34 kV, respectively, when the initial energy of 0.36 kJ was supplied into that system with the load of 0.4 μH. Within the tested range of inductance ratio, energy amplification ratio was found to be highly dependent on the inductance ratio of serial- and parallel-connected HMCG systems to load, which to be optimal around 500 was turned out. The experimental results showed that the output energy and voltage of load are controlled by connecting HMCGs in series or parallel.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.22 no.6
• /
• pp.516-521
• /
• 2009

X-ray system which is usefully used in diagnosis of the patient, being bombed of radioactivity is a big weak point when irradiates a X-ray to the human body so that ICRP restricted the radiation exposure tolerance of the human body. In order to reduce being bombed, the many research and development is now advanced. A lots of diagnostic X-ray machines have currently used due to the increase of occurrence efficiency of X-ray and precisely the output control by using the inverter which is a high speed switching semiconductors. For getting the confidence of the X-ray machine, the same radiation occurrence, same evaluation, and same irradiation condition are necessary when evaluates X-ray irradiation. It is the most important part for the accuracy of the test result and the patient safety. This research has produced the high voltage occurrence system of full-wave rectification method by using the LC resonance inverter, and evaluated the irradiation reproducibility in order to use it in diagnosis of the patient.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.38 no.8
• /
• pp.650-657
• /
• 1989

The conversion efficiency of an ozone generator can be significantly improved by modifying the discharge electrode of a helical strip line rod-to-cylinder type ozone generator to a pyramid-project-embossed rod, and by using a pulse corona discharge. Parametric studies have been carried out to obtain optimum values of peak pulse voltage, pulse forming capacitance, feeder cable and ozone generator capacitance, interelectrode spacing and corona tip density of ozone generator, and feed air flow rate and temperature. The generated ozone concentration was very dependent upon the value of pulse forming capacitance, feeder cable and ozone generator capacitance, and corona tip density. Maximum conversion efficiency was obtained with a pulse forming capacitance of about 500pF, 75pF matched feeder cable and ozone generator, and a corona tip density of 16mm. When operated at optimum values, ozone yield of 79, 99, 80 g/KWh for the different interelectrode type ozone generators tested were obtained, which are approximately 30% higher than that of an industrial ozone generator.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.11a
• /
• pp.468-471
• /
• 2002

A strong need to improve the quality of electric power is increased because of increasing use of the sensitive and small-sized electronic devices. The surges on the low-voltage ac power lines are induced by nearby lightning return strokes, and the facilities for HA, OA, FA, ME as well as computer are easily damaged by high-voltage transients. The behaviors of lightning surge characteristics transferred from the primary winding to the secondary winding in distribution transformers using a Marx generator were experimentally investigated. The transfer characteristics of lightning surge associated with a custom service ground of secondary side were also examined.

• Journal of Power Electronics
• /
• v.16 no.6
• /
• pp.2221-2230
• /
• 2016

Voltage and frequency stability issues occur in existing centralized power system due to the high penetration of renewable energy sources, which decrease grid absorptive capacity of them. The grid-connected inverter that mimics synchronous generator characteristics with inertia characteristic is beneficial to electric power system stability. This paper proposed a novel three-phase four-wire grid-connected inverter with an independent neutral line module that mimics synchronous generators. A mathematical model of the synchronous generator and operation principles of the synchronverter are introduced. The main circuit and control parameters design procedures are also provided in detail. A 10 kW prototype is built and tested for further verification. The primary frequency modulation and primary voltage regulation characteristics of the synchronous generator are emulated and automatically adjusted by the proposed circuit, which helps to supports the grid.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.17 no.3
• /
• pp.32-39
• /
• 2003

The output voltage of synchronous generator is regulated constantly by field current control in excitation system High frequency PWM converter (current control mode buck converter) type excitation systam fer synchronous generator is able to control exciter current when the load change happened. This paper deals with the design and evaluation of the excitation system for a synchronous generator to improve the steady state and transient stability. The simulation and experimental results show that the proposed excitation system is able to improve the response time by the DVR(digital voltage regulator) of 50[kW] synchronous generator.