• Proceedings of the KIPE Conference
• /
• 2001.10a
• /
• pp.727-730
• /
• 2001

Electrical wire explosion (EWE) is characterized by great current density and rapid metal heating, which make itself an ideal tool for nano-materials manufacturing technology. The EWE requires a high voltage electric-energy source. In the current experimental set-up a high voltage capacitor is used for the purpose. Hence, a power supply that is capable of charging the capacitor to a target voltage is required. One of the special requirements is the precise controllability of the stored energy level in the capacitor. Through this study a high voltage capacitor charger using a series resonant converter technology has been developed for the production of nanosize powder. A load capacitor of $32{\mu}F$ can be charged up to 20kV by the developed capacitor charger and discharged through a gap switch and a copper wire.

• Proceedings of the KIEE Conference
• /
• 1999.07e
• /
• pp.2204-2206
• /
• 1999

Pulsed Nd:YAC laser is used widely for materials processing and instrumentation. It is very important to control the laser energy density in materials processing by a pulsed Nd:YAG laser. A pulse repetition rate and a pulse width are regarded as the most dominant factors to control the energy density of laser beam. In this study, the alternating charge-discharge system was designed to adjust a pulse repetition rate. This system is controlled by one chip microprocessor and allows to replace an expensive condenser for high frequency to a cheap condenser for low frequency. In addition. we have investigated the current pulse shape of flashlamp and the operating characteristics of a pulsed Nd:YAG laser. As a result, it is found that the laser output of the power supply using the alternating charge-discharge system is not less than that of typical power supply. As the pulse repetition rate rises from 30pps to 120pps by the step of 30pps at 1200V, it is found that the laser efficiency decreases but the laser output power increases about 6W at each step.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.6
• /
• pp.2561-2567
• /
• 2018

The extension of DC battery backup time in the DC power supply system of nuclear power plants (NPPs) remains a challenge. The lead-acid battery is the most popular at present. And it is generally the most popular energy storage device. However, extension of backup time requires too much space. The lithium-ion battery has high energy density and advanced gravimetric and volumetric properties. The aim of this paper is development of the sizing formula of stationary lithium-ion batteries. The ongoing research activities and related industrial standards for stationary lithium-ion batteries are reviewed. Then, the lithium-ion battery sizing calculation formular is proposed for the establishment of industrial design standard which is essential for the design of stationary batteries of nuclear power plants. An example of calculating the lithium-ion battery capacity for a medium voltage UPS is presented.

• Proceedings of the KIPE Conference
• /
• 2006.06a
• /
• pp.206-209
• /
• 2006

At present, the cold cathode fluorescent lamp (CCFL) using mercury lamp has been generally used far liquid crystal backlight source of personal computer and car navigation and so on. This kind of lamp is more excellent on luminance performance and cost. However, the requirements of liquid crystal backlight due to a light source without mercury have been strongly increased from a viewpoint of the actual influence on environmental preservation and environmental recycling. As fluorescent lamp without mercury, Dielectric Barrier Discharge based rare gas fluorescent lamp (DBD-FL) using xenon (Xe) gas has been studied so far. This DBD lamp has no influence on the human body and environmental recycle. Its operating life is long because electrode is out. In this paper, the simulation and experimental results of soft switching high frequency inverter with reverse blocking single switch as a high frequency power supply circuit for DBD-FL using Xe gas are comparatively evaluated and discussed from a practical point of view.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.2152-2153
• /
• 2011

According to a sharp increase in demand for electricity supply secure, and $CO_2$ regulation in accordance with global environmental problems and to solve problems, etc. These factor less pollution, higher energy conversion hyoyulin way that the new electrical equipment, nano-composites The rapid degeneration of the unit study utilizing the power that is required is Free. Accordingly, cables, transformers and switchgear (GIS)-capacity of power equipment, such as, high-voltage high-density along with the miniaturization of equipment have made angry the reliability of these devices is becoming a very important issue. Insulation materials used in electrical equipment for high voltage withstand, power equipment, power equipment due to aging and overloading caused by a weakening of the insulation failure and replacement in accordance with the age due to increased costs because of the reliability of electrical equipment should be secured should. Therefore, improved performance and longevity of insulation material is recognized as an important challenge. In this study, power isolation and degeneration of the unit for use in various parts of the molding epoxy resin to improve the insulation performance of the epoxy resin by varying the added amount of nano-SiO2 nanocomposites made epoxy/SiO2 analysis and breakdown properties of the experiment want to improve the electrical properties through the geometry.

• Transactions of the Korean hydrogen and new energy society
• /
• v.12 no.3
• /
• pp.211-217
• /
• 2001

From wood to coal and petroleum, mankind has used various fuel. Since using such fuel, mankind has developed power source of mechanism. We obtain numerous power from caloric force. Present energy supply is based on the fossil fuel. Fossil fuel has high energy density and is convenient for transportation and storage. Human being prepared countermeasure of energy economy, high energy efficiency and substitution energy for limits of fossil fuel. High energy efficiency among them is very important. This research will improve total output by physical exergy recovery of $LH_2$-fuel cell system.

• Journal of IKEEE
• /
• v.25 no.3
• /
• pp.528-533
• /
• 2021

This paper presents the PCB heat dissipation characteristics of high density DC-DC converter for electric vehicles. This paper also analyzes the heat dissipation structure of the high density DC-DC converter and optimizes the PCB heat dissipation design of the high density power system through thermal analysis simulation. Based on heat transfer theory, the thermal path of general electronic devices is analyzed and the thermal resistance equivalent circuit is modeled in this paper. Additionally, the thermal resistance equivalent circuit of the 500W synchronous buck converter, which is addressed in this paper, is modeled to present a structural heat dissipation path for better thermal performance. The validity of the proposed scheme is verified through the thermal analysis simulation results and experiments applying multi-surface heat dissipation structure to a 500[W](12[V], 41.67[A]) synchronous buck converter prototype with an input voltage 72[V].

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.15 no.10
• /
• pp.831-837
• /
• 2002

Scaled SONOS transistors have been fabricated by 0.35$\mu\textrm{m}$ CMOS standard logic process. The thickness of stacked ONO(blocking oxide, memory nitride, tunnel oxide) gate insulators measured by TEM are 2.5 nm, 4.0 nm and 2.4 nm, respectively. The SONOS memories have shown low programming voltages of ${\pm}$8.5 V and long-term retention of 10-year Even after 2 ${\times}$ 10$\^$5/ program/erase cycles, the leakage current of unselected transistor in the erased state was low enough that there was no error in read operation and we could distinguish the programmed state from the erased states precisely The tight distribution of the threshold voltages in the programmed and the erased states could remove complex verifying process caused by over-erase in floating gate flash memory, which is one of the main advantages of the charge-trap type devices. A single power supply operation of 3 V and a high endurance of 1${\times}$10$\^$6/ cycles can be realized by the programming method for a flash-erased type EEPROM.

• Journal of Power Electronics
• /
• v.19 no.4
• /
• pp.980-988
• /
• 2019

When compared with traditional power frequency generators, the frequency of a super high-speed permanent magnet generator (SHSPMG) is a lot higher. In order to study the influence of frequency on the electromagnetic field of SHSPMGs, a 60000rpm, 117kW SHSPMG was taken as a research object. The two-dimensional finite element model of the generator was established, and the two-dimensional transient field of the generator was simulated. In addition, a test platform of the generator was set up and tested. The reliability of the simulation was verified by comparing the experiment data with that of the simulation. Then the generator electromagnetic field under different frequencies was studied, and the influence mechanism of frequency on the generator electromagnetic field was revealed. The generator loss, voltage regulation rate, torque and torque ripple were analyzed under the rated active power load and different frequencies. The influences of frequency on the eddy current density, loss, voltage regulation rate and torque ripple of the generator were obtained. These conclusions can provide some reference for the design and optimization of SHSPMGs.

• Proceedings of the KIEE Conference
• /
• 2003.07a
• /
• pp.555-557
• /
• 2003

As electric power transmission systems grow to supply the increasing electric power demand, transmission capacity is larger. but that's really difficult to secure the location for power transmission and distribution to user. The high temperature superconducting(HTS) cable is a method to solve this problem. But for applying to real systems, it needs to investigate the effect of HTS cable. The most important things is the investigation of fault condition. the fault on HTS cable include the quench state. When a fault occur in a circuit, three critical parameters(temperature, current density, magnetic field) exist. when one of these parameters exceeds the critical value, the superconducting becomes normal-conducting. f the cooling power is insufficient to recover the superconducting state, the normal-conducting zone expands. In order to solve these problem, this paper present simulate the quench state considering the over-current and over-voltage in the informal circuit and analyze the quench state.