• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.683-684
• /
• 2007

설계기준상 지지물의 적용길이는 과거에는 직선주, 분기주, 변대주 등 장주와 적용지역에 따른 최소길이를 규정하여 운영하였으나 변압기, 개폐기 등 기기설치로 인한 빈번한 전주교체를 예방하고 CATV선 첨가 및 부하증가에 대비하고자 지역별 전주의 표준길이로 1995년에 기준을 변경하여 운영하였다. 그러나 배전설비 운전여건은 배전 공가사업의 확대에 따른 지상고 기준 제정, 토질등급 세분화에 따른 전주의 근입 확대, 태풍대비 배전설비 운영기중 강화 등 변화하고 있고, 설계기준의 엄격성으로 인하여 적용기준을 세부화 할 필요성이 있음.

• Proceedings of the KIEE Conference
• /
• 2006.07e
• /
• pp.59-60
• /
• 2006

A shorted-turn test was performed at the Pyungtaek combined cycle power plant on gas turbine generators. The test was conducted using a permanent flux probe and on-line shorted-turn diagnosis system. The permanent flux probe installed in the generator air gap senses the field winding slot leakage flux and produces a voltage proportional to the rate of change signature unique to each field winding. We have also applied a voltage waveform analysis technique that can identify the pole location, slot number and number of shorted-turn with each slot.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.12
• /
• pp.3567-3573
• /
• 2009

This research proposed a dashpot type mount design using MR fluids, and investigated experimentally the influence of the design parameters of the dashpot MR fluid mount, which affect the damping forces of the dashpot MR fluid mount. In order to observe the influence, the dashpot MR fluid mount which have the different effective length and the core structure is manufactured. The variations of the resistance forces according to different effective lengths of the magnetic pole of MR fluid mount, along which magnetic field is defined, was investigated. It was founded that the resistance forces from the MR mount decreased with increased input frequencies, while increased with increased applied electric current intensities. Nevertheless, there is no appreciable change in the resistance forces with respect to the effective length variations of the magnetic pole of MR fluid mount.

• Journal of Electrical Engineering and Technology
• /
• v.8 no.6
• /
• pp.1424-1430
• /
• 2013

This paper presents design procedure of the magnetic bearings used for high-speed electric machines and flywheel energy storage systems. Magnetic bearing can be categorized by inner-rotor type and outer-rotor type according to the position of the rotary disc. These two types are applicable based on application environments such as application space, required attraction force, and controllability. Magnetic bearing is generally designed based on the ratio (geometrical coefficient or geometrical efficiency) of pole width to rotor journal radius but proper ratio is only decided by the analysis. This is the difficulty of the magnetic bearing design. In this paper, proper design technology of the inner-rotor type and outer-rotor-type eight pole magnetic bearings is introduced and compared with the FEM analysis results, which verifies the proposed design procedure is suitable to be applied to the design of the magnetic bearings for the industrial applications and flywheel energy storage system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.7
• /
• pp.84-93
• /
• 2007

The pole transformer is one of the most important facility to insure the stability of electric power supply. which distributes electricity to customers directly. However there are a lot of defects which are caused by manufacturing fails(in 3 years) or deterioration (in 13 years), so we need a more improved transformer which insures quality. This thesis talks about the development of the new-type transformer using the hybrid insulation that is durable thermally, mechanically, and electrically. It would show how to lay out and produce the transformer using the hybrid insulation. And finally we are sure that we could increase the utilization rate of a transformer by 160% as compared with its own capacity through the overload test. Also, we carried out the examination about the short-circuit and insulation with a 100[kVA] model transformer, so that we expound the analysis of magnetic-mechanical forces intensity and the measure for improving short-circuit efficiency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.12
• /
• pp.1050-1057
• /
• 2015

This paper presents the characteristics of broadband double-cone antennas. The antenna is used to measure electromagnetic fields(2~5 GHz) radiated from a primary or a secondary electrode of a pole-transformer when partial discharge occurs inside the pole-transformer. The theoretical analysis is conducted using commercial software based on a finite difference time domain(FDTD) method. The parameters are a radius, and a height of the broadband double-cone antennas, and the number of posts on a ground plane. This paper examines influences of structural parameters of the broadband double-cone antennas on return loss. The results show that a condition for an optimum structure of broadband double-cone antennas exists. It also shows that the broadband double-cone antennas have radiation patterns similar to those of a dipole antenna. Therefore the broadband double-cone antennas are appropriate for the measurement of radiated electromagnetic fields from the pole-transformer. To verify the theoretical analysis, computed results are compared to experimental results.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.10
• /
• pp.48-57
• /
• 2008

MR Fluid, one of functional fluids, is developed for the application to automobile products. MR CDC damper using MR fluid has following principles. When ar electric current is applied to the solenoid, apparent viscosity of MR fluid passing through the annular gap which acts as magnetic circuits varies directly as the intensity of the current. These devices have a simple structure and excellent lime response characteristics, emerging as the alternatives of the conventional semi-active suspension systems. In this study, a design procedure of the magnetic circuit through the solenoid fore and the flux ring functioning as a magnetic path is investigated so as to optimize the design and performance of MR CDC dampers for the vehicles. In addition, an operating point on the B-H curve, the magnetization according to the variation in the annular gap, the pole piece width and the density of MR fluid are studied to design the optimal piston head within the restrained dimension range.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.67 no.1
• /
• pp.142-147
• /
• 2018

Private electrical facilities are judged whether it is suitable for the insulation aging condition of their incoming underground cables using DC leakage current test method. In the case where the service point of utility is the secondary side of cut out switch installed in the electric pole, there is a problem that it is difficult to separate the lightning arresters(LA) because of their high position of the pole. Therefore, the field test voltage is applied at value lower than DC 30 kV, which are stated in the inspection guideline. However, this test could reduced the insulation performance of the LA by accelerating the electrical stress of the metal oxide varistor element in the pre-breakdown region. In this study, we analyzed the relationship between the DC test voltage and the leakage current using the non-destructive DC high voltage equipment with leakage current measurement function. The results show that the leakage current increases sharply above the specified test voltage. As a consequence, it could be contributed to improve insulation aging inspection method by selecting the possible test area on the VI characteristic curve of the pre-breakdown area of the LA.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.13 no.5
• /
• pp.371-383
• /
• 2011

It is important to secure illumination for the driver's safety because the tunnel is a space for changing brightness quickly, and lighting fixtures of the tunnel have consumed a lot of electric lighting energy for operating in both the daytime and at night. This study aims to evaluate daylighting performance of Mirror Reflector System for luminous environment improvement of tunnel space by using RADIANCE simulation program. The results of simulation show that illuminance of bar type is higher than illuminance of pole type at 20 m from the tunnel entrance.

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.497-499
• /
• 2004

Due to a typhoon named MAEMI on Sep12, 2004, 7 transmission towers collapsed and 3 were damaged in the Gyeongnam and Busan areas. These caused long-term black-outs in Goeje-do. When a transmission tower collapses or is damaged, Construction will take more than 2 months and this will be accompanied by long-term black-outs. Therefore a temporary iron pole is used in such emergencies. Current temporary rehabilitation angle steel iron Pole consistes of around 800 members, 2,800 bolts and it takes about 5 days to construct a temporary transmission line. Consiquently wide black-outs occur during the construction of the temporary transmission line. To reduce black-out time, the construction period must be reduced as much as possible. This paper presents new methods to reduce temporary transmission line construction time to within 48 hours by applying a self-reliance assembling method instead of the current man power assembling method and by modulizing each angle steel with duralumin.