• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.52 no.8
• /
• pp.481-485
• /
• 2003

In electric railway system, potential of rail has been risen, for return-current flows through rail. The magnitude of rising voltage is different to railway feed system, ground admittance of rail and the load current. If rising voltage of rail is large, electric shock can be occurred to passengers and maintenance- worker, In this paper, we estimate the rising voltage of rail in high speed railway system and check the safety to human beings.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.10
• /
• pp.1451-1457
• /
• 2002

When an aqueous liquid such as water having high electric conductivity and high surface tension is discharged from a nozzle under a strong DC electric field, fine drops ranging from 30 to 450 microns can be obtained only through the spindle mode. In the present study, effects of the electric conductivity and the surface wettability of nozzle materials on formation of drops with this mode were investigated. For that, three nozzles with the same size but with different materials were prepared and tested; a stainless steel needle, and a plain and a metal (gold)-coated (except for the tip portion) silica needles. Uniform drops were obtained with the gold-coated silica nozzle over the wider range of the DC voltage input. That is, formation of the liquid cone and detachment of the liquid spindle (ligament) can be more stabilized and frequent with the needles having high electric conductivity but with low surface wettability at their tips.

• Proceedings of the KIEE Conference
• /
• 2001.11c
• /
• pp.280-283
• /
• 2001

Recently Many technologies of the Powerline communication are proposed these technologies used high carrier frequency for high speed and stability, but high carrier frequency is restricted by the low of electric wave. So we will propose electric monitoring system that used the commercial powerline communication modem, isn't restricted by the low. Our objects are, first, we compared the low in korea, EU(CENELEC), and USA(FCC). second, proposed a spec of the powerline communication modem. third, design that the electric monitoring system using commercial A/D converter control and manage the electric equipment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.369-370
• /
• 2008

This paper describes the electric field distribution of high voltage polymer bushing with inner field shaper designs. The field control can be achieved by means of the designs of such internal field shaper. But high electric stress occurred between field shaper and central conductor by the closely space. In accordance, the floating and ring shield designs was importance for electric stress grading at critical parts of the bushing. The bushing has a central conductor, and internal ring shield or floating shield, gaps are formed between field shaper and ring shield. Accordance equipotential lines extend through gaps. Maxwell 2D simulator based on the boundary element method was also introduced in order to verify the reliability of the polymer bushing.

• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.1841-1843
• /
• 1996

To meet recent increasing demand for electric power in large cities in Korea, and to improve reliability of the power supply. Especially, demand for electric power apparatus places great emphasis on not only function but also environmental factors. In this paper, environpolitics describes according to large capacity demand for extra high voltage underground transmission lines and high reliability of the power supply.

• Proceedings of the KSR Conference
• /
• 2004.10a
• /
• pp.1303-1308
• /
• 2004

This paper proposes a reduction method for the mis-operation analysis of the DC High Speed Circuit Breaker(HSCB) in electric railway substation system. The analysis method is based on present condition of operation which is a method for accuracy level up. There is reason to operation of HSCB that it is mis-operation of fault detection relay(50F), operation of ground fault relay(64P), and trouble of electric car. A countermeasure is relay resetting through field test, induction of GTOCB(Gate Turn Off Thyristor Circuit Breaker), HSVCB(High Speed Vacuum Circuit Breaker), coordination with electric car. The results presented in the paper can be used as a reference for maintenance free in electric railway substation system.

• Proceedings of the KIEE Conference
• /
• 2003.07c
• /
• pp.1716-1718
• /
• 2003

In order to realize the PDP that is better than CRT TV, high luminance and high efficient PDP panel should be fabricated. In order to meet these conditions it is inevitable trend to use high Xe% gas working gas. In this paper, we studied the relationships between the static margin, the discharge delay and jitter of PDP and Xe% in Ne gas.

• Proceedings of the KIEE Conference
• /
• 1995.07a
• /
• pp.420-423
• /
• 1995

The electric arc welding machine with high-frequency inverter is studied in this paper which could make more saving in energy than conventional ones with inherent low efficiency. The inverter circuit has been already adopted to special welding machines such as MIG and TIG for improving operating performances so much. But this adoption has not be applied to conventional ac arc welding machine until now. The proposed technology for higher efficiency is to apply the high frequency inverter, together with noise-cut transformer. Overall output characteristics are investigated in aspect of cost and circuit performance. The proposed system is conducted practical experiments using PWM controller.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.10
• /
• pp.1454-1460
• /
• 2012

In order to develop an new electric insulation material for heavy electric equipments, epoxy/micro/nano composite (EMNC) was prepared by mixing micro-silica with nano layered silicate, where the nano layered silicate was synthesized by our electric field dispersion method, EMNSC was prepared by treating the EMNC with a silane coupling agent. Thermal properties such as glass transition temperature (Tg) and thermal expansion coefficient, and DMA characteristics were studied, and mechanicla properties such as tensile and flexural tests were performed. AC electrical insulation strength was also tested. All properties of EMNSC were modified by treating EMNC with silane coupling agent and it was confirmed that our new developed composites could be used in the heavy electric equipments.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.58 no.3
• /
• pp.351-356
• /
• 2009

In this study, we analyzed and experimented about electric continuity for human body safety from green cars. And we compared power systems of HEV and examined about human body effect of current and time. We investigated internal and external standards and regulations for human body safety from high voltage electrical equipments. Indirect contact refers to contact between the human body and exposed conductive parts. According to UNECE R100, ISO 23273-3, ISO 6469-3 and Japanese Regulation Attachment 101, electric continuity between any two exposed conductive parts shall not exceed $0.1{\Omega}$. The value of electric continuity was measured below $0.1{\Omega}$ at the actual condition of green car. We expected that the results of these experiments can utilize to data for electrical safety of green car.