• The Transactions of the Korean Institute of Power Electronics
• /
• v.16 no.6
• /
• pp.627-637
• /
• 2011

To cope with the high power density and low cost in switching power supply, this paper presents a novel planar transformer, which can regulate the leakage inductance of planar transformer used for LLC resonant converter. Modeling and analysis of a novel planar transformer are discussed in detail and a prototype 200W LLC resonant converter is tested to verify.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.181-186
• /
• 2002

Lately, as going on increasing in the demand of high power density(power/weight), it is necessary for hydraulic axial piston pump/motor to operate more high pressure and speed. But in these condition, there are some trouble like as friction loss. To reduce this friction loss, hydrostatic bearing is used far axial piston pump/motor frequently. In general, it is difficult to measure accurate friction torque of spherical hydrostatic bearing in the use of the existing devices. So, we have developed the measurement device using the reaction torque sensor to obtain the pure friction torque, fitted in the casing. In this report, we intend to make an introduction about this measurement device for friction torque of the spherical wear part and clarify the effect of friction characteristics on supply pressure and rotational speed with three types of pocket size by using this measurement device.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.11a
• /
• pp.1023-1027
• /
• 1996

In this paper, the new technology and R&D status is presented, which accelerates the projectile using the electrical energy to overcome the limit of the conventional gun. The ETC (electro_thermal_chemical) gun, one kind of electric guns, seems to be the highly probable candidate as the next generation gun. The high density power supply and the forming and control of the current pulse are required to develop the ETC gun. And, the interior ballistics considered the mechanism of ETC gun must to be studied.

• Progress in Superconductivity and Cryogenics
• /
• v.26 no.1
• /
• pp.1-4
• /
• 2024

This study explores the use of a bulk type high-temperature superconductors (HTS) as trapped field magnets in synchronous motors. A HTS bulk is examined for its ability to generate powerful magnetic fields over a permanent magnet and to eliminate the need for a direct power supply connection compared to a tape form of HTS. A 150 kW interior-mounted bulk-type superconducting synchronous motor is designed and analyzed. The A-H formulation is used to numerical analysis. The results show superior electrical performance and weight reduction when comparing the designed model with the conventional permanent magnet synchronous motor of the same topology. This study presents HTS bulk synchronous motor's overall design process and highlights its potential in achieving relatively high power density than conventional permanent magnet synchronous motor.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.31 no.11
• /
• pp.942-948
• /
• 2007

Popular techniques for producing hydrogen by converting methane include steam reforming and catalyst reforming. However, these are high temperature and high pressure processes limited by equipment, cost and difficulty of operation. Low temperature plasma is projected to be a technique that can be used to produce high concentration hydrogen from methane. It is suitable for miniaturization and fur application in other technologies. In this research, the effect of changing each of the following variables was studied using an AC GlidArc system that was conceived by the research team: the gas components ratio, the gas flow rate, the catalyst reactor temperature and voltage. Results were obtained for methane and hydrogen yields and intermediate products. The system used in this research consisted of 3 electrodes and an AC power source. In this study, air was added fur the partial oxidation reaction of methane. The result showed that as the gas flow rate, the catalyst reactor temperature and the electric power increased, the methane conversion rate and the hydrogen concentration also increased. With $O_2/C$ ratio of 0.45, input flow rate of 4.9 l/min and power supply of 1 kW as the reference condition, the methane conversion rate, the high hydrogen selectivity and the reformer energy density were 69.2%, 32.6% and 35.2% respectively.

• Transactions of the Korean hydrogen and new energy society
• /
• v.18 no.2
• /
• pp.132-139
• /
• 2007

Popular techniques for producing synthesis gas by converting methane include steam reforming and catalyst reforming. However, these are high temperature and high pressure processes limited by equipment, cost and difficulty of operation. Low temperature plasma is projected to be a technique that can be used to produce high concentration hydrogen from methane. It is suitable for miniaturization and for application in other technologies. In this research, the effect of changing each of the following variables was studied using an AC Glidarc system that was conceived by the research team: the gas components ratio, the gas flow rate, the catalyst reactor temperature and voltage. Glidarc plasma reformer was consisted of 3 electrodes and an AC power source. And air was added for the partial oxidation reaction of methane. The result showed that as the gas flow rate, the catalyst reactor temperature and the electric power increased, the methane conversion rate and the hydrogen concentration also increased. With $O_2/C$ ratio of 0.45, input flow rate of 4.9 l/min and power supply of 1 kW as the reference condition, the methane conversion rate, the high hydrogen selectivity and the reformer energy density were 69.2%, 36.2% and 35.2% respectively.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.65 no.4
• /
• pp.285-291
• /
• 2016

A light-emitting diode (LED) has been increasingly applied to various industrial fields and general lightings because of its high efficiency, low power consumption, environment-friendly characteristic and long lifetime. To drive the LED lighting, a power converter with the constant output current is needed. Among many power converters, the flyback converter is chosen by many converter designers due to high power density, structural simplicity, and miniaturization. In this converter, an electrolytic capacitor is generally chosen for the stabilization of the DC voltage because of having the large capacitance and the low price. However, the disadvantages are the short expected life time and 120Hz ripple currents on the converter output node. In this paper, a single-stage dimmable PFC DCM flyback converter without the electrolytic capacitor is proposed to prolong the lifetime of the LED driver. For the long lifetime of the converter, the polyester film capacitor with the small capacitance is substituted for the electrolytic capacitor on the output node and an LC resonant filter is added to damp 120Hz ripple current. The proposed converter is verified through the simulation and the experimental works.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.1383-1388
• /
• 2010

The latest generation of tram is low-floor design, various nations in europe and japan have developed battery driven hybrid trams that combine battery and wiring. Battery driven tram system is achieved by contactless power supply system, thus system is needed high efficiency, high power and low weight traction motor for maximization of energy efficiency. Research from abroad is still in induction motor(IM) application, and it is not meet the efficiency and the power per unit volume in IPMSM. In this paper, we design compare IM and IPMSM to apply battery driven tram, and then compare these motors. To design the motor, we estimate the loading condition at first. Loading condition includes rolling resistance, air-drag resistance, and slope resistance. Based on the loading condition by estimation, we determine the power and compute rated voltage and rated current. In this paper, voltage is limited by battery voltage level. As a result, volume about IM is 1.98 times bigger than IPMSM under same condition. Even though IPMSM is bigger than IM in power density per volume, we consider more factors for actual application because there are demagnetization of permanent magnet in IPMSM and so on by external environment conditions.

• Transactions of the Korean hydrogen and new energy society
• /
• v.9 no.1
• /
• pp.1-7
• /
• 1998

Most of today's energy supply is obtained from fossil fuels. Despite of high energy density, higher store efficiency and long mileage, fossil fuels cause environmental pollution and their reserves are limited. In this study pure hydrogen gas and oxygen gas are burned without the emission of pollution. A gas turbine is used to obtain power. Water is injected into a combustor, which prevents overheating and recovers cooling heat. Excessively supplied water is recirculated. With variation of mass flow rate and equivalence ratio, the affection of water injection rate and the temperature of injected water on efficiency and power are experimented. Injected water gets cooling heat, is expanded from liquid to vapor and raises the thermal efficiency. It is enable to determine the rate of water injection, which makes the maximum power. The increase of temperature of water injection raises the efficiency of the system.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.11
• /
• pp.2758-2764
• /
• 2015

In the field of electronic warfare applications, high voltage power supply(HVPS) for high power phased array transmitters must necessarily have an independent operating characteristics for driving mini TWTs. TWT independent operational characteristics, in order to run without interrupting the electronic warfare mission by maintaining the partial transmission function even when one of the TWT has occurred a failure, is known to be very important. In this paper, we describe the research on high-speed independent control system using a high-density HVPS, including FE modulators, hardware configuration and the FPGA in order to independently operate mini TWTs. Also, we have simulated some possible faults in phased array transmitters, and presents the test results to control a faulted TWT independently.