• Proceedings of the KIEE Conference
• /
• 2004.07c
• /
• pp.1658-1660
• /
• 2004

Use of higher voltage and higher capacity of power systems and their equipment is leading to an increase in the size of the entire system. In order to reduce the cost of constructing a substation, it is necessary to reduce the size of equipment. So, this paper described optical sensor, which exploited the electric and magnetic potentiometer to sense the measured voltage and current of medium voltage GIS. It can be used both in measurement and in protection relays as its well linearity, rapid response, broad dynamic range, wide frequency band, no magnetic saturation, small in volume, light weight, and saft in insulation.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.78-81
• /
• 2011

Generally, vehicle is insulated from the earth by rubber tire which is intrinsically the insulation material. The electrical ground of vehicle was floated in the sense of electric potential over the electric power sources. First of all, the floated electrical ground of vehicle should be equipotentially connected with the (-) line of electrical equipment. Bimodal tram has the different kinds of electric system. They must be kept insulated to each other electrically. When there is some unbalanced event or connection between them, it will invoke some errors or breakdown to electrical devices including sensors and actuators. This paper has investigated the floating ground effect of bimodal tram built with composite body and shown the effect according to the unbalanced ground of vehicle and the connection between different electric systems.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.2043-2048
• /
• 2011

According to the statistical report from National Emergency Management Agency (NEMA) in Korea, the accident rate of closed switchboards in power systems occupies over 40%. In this paper, an integrated sensor module for monitoring the condition of closed switchboards is described. The sensor module monitors electro-magnetic (EM) wave, ultra-violet (UV) ray, heat and smoke generated by electrical discharges or insulation breakdown. The effective detection ranges were decided from experiment results; 100 kHz~10 MHz for EM wave, 220 nm~395 nm for UV ray and 0~$150^{\circ}C$ for heat, respectively. The prototype sensor module includes all functions above-mentioned in one device.

• Tribology and Lubricants
• /
• v.29 no.5
• /
• pp.318-323
• /
• 2013

Overheating in electrical motors results in detrimental effects such as degradation of the insulation materials, demagnetization of magnets, increases in Joule losses, and decreases in motor efficiency and lifetime. Thus, it is important to find ways to dissipate heat from the motor and to keep the motor operating at its most efficient temperature. In this study, a new design to guide air flow through a given brushless direct current (BLDC) motor is developed and the design is analyzed, specifically by using computational fluid dynamics (CFD) simulations. The results showed that the temperature distribution in the three proposed models is lower than that in the original model, although the speed of the cooling fan in the original model reaches a very high value of $15{\times}10^3$ rpm. The results also showed that CFD can be effectively used to simulate the heat transfer of BLDC motors.

• Proceedings of the KIEE Conference
• /
• 1991.11a
• /
• pp.415-418
• /
• 1991

This paper described an instrument for the detection and geometric location of partial discharge(PD) sources in oil transformer. This instrument measures electric current pulse and ultrasonic pulse simultaneously in order to determine the geometric location of PD in transformer. Laboratory experiment systems are made for detection and location of PD in oil transformer. It was observed that there are effects of the barrier, such as insulation papers, silicon steel plate and actual transformer with location and detection of PD in model transformer. Through the laboratory actual test, it was clarified that this measurement device could be used satisfactorily for location of pd in oil transformer.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.824-828
• /
• 2007

In this paper Statistical Energy Analysis has been considered to predict middle, high frequency air borne interior noise. PIM method is used for verification. Damping loss factor and coupling loss factor have been derived from the response(SPL) of sub systems when the power is applied. The airborne SEA model of vehicle is modeled through AutoSea2. Insulation material's absorption coefficient and transmission loss are acquired from closed form solution and experiment.

• Transactions on Electrical and Electronic Materials
• /
• v.14 no.1
• /
• pp.43-46
• /
• 2013

In order to develop electrical insulation material, organically modified layered silicate was incorporated into an epoxy matrix to prepare nanocomposite. Transmission electron microscopy (TEM) observation showed that organophillic clay was in an exfoliated state, while hydrophilic clay was not dispersed into nanolayers within the epoxy matrix. Epoxy/organophilic clay (2.8 wt%) nanocomposite was mixed and cured at $150^{\circ}C$ for 4.5 hr. I-V characteristics, volume resistance and dielectric properties for the cured nanocomposite were estimated. Current density increased with increasing temperature, and volume resistance decreased with increasing temperature, in neat epoxy and epoxy/organophilic clay (2.8 wt%) nanocomposite. As frequency increased, the dielectric loss value decreased in the two systems.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.58 no.2
• /
• pp.184-189
• /
• 2009

Lightning has been identified as one of the leading causes of outages on transmission and distribution systems. As sensitive loads and reliance on electric power increase year by year, it is getting more focus on stable and high quality of power supply. To protect the transmission and distribution line from lightning, the transmission lightning arrester can be the effective facility on the power system. This paper discusses Gapped type Arresters application results by analysing effects of lightning arresters on transmission and distribution line.

• Proceedings of the KIEE Conference
• /
• 2008.10a
• /
• pp.103-104
• /
• 2008

this paper describes the electric field distribution analysis along a shield gap inner vacuum interrupter(VI). The equipotential line and electric field and field vector in a VI are analysed by a finite element method and experiment at shield gap. in result, The equipotential line and electric field distribution was affected to VI shield gap. The reason is as it gets distortion of equipotential line done. finally, this paper recognized whether or not affected, and proposed gap with the most suitable shield length and an external insulation.

• The Korean Journal of Pain
• /
• v.23 no.1
• /
• pp.78-81
• /
• 2010

Spinal cord stimulation (SCS) has become an established clinical option for treatment of refractory chronic pain. Current hardware and implantation techniques for SCS are already highly developed and continuously improving; however, equipment failures over the course of long-term treatment are still encountered in a relatively high proportion of the cases treated with it. Percutaneous SCS leads seem to be particularly prone to dislocation and insulation failures. We describe our experience of lead breakage in the inserted spinal cord stimulator to a complex regional pain syndrome patient who obtained satisfactory pain relief after the revision of SCS.