• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.2
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• pp.59-61
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• 2006

In our country most of transmission lines are double-circuit lines. In these lines, the combining method of increasing conductor height and installation of passive shield-loop to mitigate magnetic field near a transmission line, is a good and feasible method. The basic principle of passive shield loop is that the field from the current induced in the shield loop conductors counteracts the field from the phase conductors. This method applied to domestic transmission lines to meet the magnetic field level, 100, 30, 10 and 4 mG, respectively. In each magnetic field level, the minimum conductor height and passive loop height are presented for the implementation of the practical design.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.559-564
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• 2004

This paper deals with the device for measuring the time-varying magnetic fields and induced voltages caused by lightning discharges. The two magnetic field measuring systems were designed and made. One consists of the loop-type magnetic field sensor with the active integrator operated by a differential amplifier. The other consists of the loop-type magnetic field sensor and Labview software. The loop-type magnetic field sensor detects the time derivative of the magnetic field being measured, and the signal detected is integrated by the Labview software. As a consequence, from the calibration experiments, the frequency bandwidth of the full measuring system ranges from 400 [Hz] to 1 (MHz) and the response sensitivity are 0.98 (mV/nT) and 22 (mV/nT) for the magnetic field sensor of 2 turns and 6 turns, respectively. Also, the results obtained by the two measuring devices well agreed with each other.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.2
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• pp.78-84
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• 2016

This paper is focused on the measurement and analysis of an atmospheric electric field which is caused by thunderclouds. The electric field due to thunderclouds changes very slowly. For this reason, the extremely low frequency E-field sensor needs to be used for measuring the atmospheric electric field strength. The balloon-carried E-field sensor system with the time constant of 1sec was designed and fabricated. The electric field sensor consists of $100mm{\times}100mm$ copper plate, active integrator, high pass and low pass filters and batteries. The measurements of atmospheric electric fields were made by the balloon-carried E-field sensor and radiosonde, which sends the data back to ground in real time. From the calibration experiments, the response sensitivity of the E-field sensor was 0.154mV/kV/m in the frequency range of less than 1kHz. As a result from the actual experiment of the atmospheric electric field, the electric field signals were observed from the altitude of about 2.5km. Also, as the altitude was increased, the detected electric field wave oscillated with the fluctuation of sensing plate. The proposed method seems suitable for measurements of atmospheric electric fields, because it is inexpensive, simple to use and launch.

• Journal of the Korean Geosynthetics Society
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• v.6 no.4
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• pp.29-37
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• 2007

Reduction Factor for Installation Damage required for calculation of design strength of geogrid used in MSEW(mechanically stabilized earth wall) design is usually obtained in the field test simulating real construction condition. However, damages occurred in geogrid during backfill work are influenced by many factors such as polymer types, unit weight per area, backfill construction method and gradation of backfill material and field test considering these factors demands lots of time and costs. In this study, factors affecting installation damage are analyzed and empirical method for evaluating reduction factor for installation damage using maximum particle size in backfill material is suggested.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.5
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• pp.234-241
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• 2005

The performance of passive conductor loop (hereinafter 'loop') method which is used to mitigate the magnetic field around overhead power transmission line is dependent on its configuration and installed location, which are affected by installation conditions of the loops such as objective areas and levels of magnetic field mitigation. Thus, because the design problem of loops is difficult and cumbersome by variety of their configuration and complexity of magnetic coupling mechanism, it is need to be formulated as a computer-based optimum problem to determine the most effective and reasonable loop model satisfying the installation conditions. In this paper, the optimum locations of the multi-wired multiple loops including series reactance compensations are searched by using the genetic algorithm (GA) to mitigate effectively the magnetic fields of relatively near points or far points from transmission line at Am height, and the magnetic fields mitigation characteristics of each loop are analyzed in the view of magnitude, direction and phase of cancellation fields by polarized vector concept to identify their adequacy and rationality for the installation objectives.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1768-1770
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• 2001

EHV power cables can take any damage during shipping, transportation, handling, storage and installation. As the damage influences a reliability of the power cable system in the short and long periods, field tests have been required, for installers, to confirm the reliability of an installed system and, for utilities, to make sure the compatibility of an installed system. Of field tests, a HV withstand test for the cable insulation has been performed to check the soundness of the insulation. For EHV XLPE power cables, the test has been done by applying a specified d.c voltage till lately. But as some problems with the d.c test is emphasized and the equipment for the a.c test is improved, the a.c test is considered positively as an after-installation test. This paper describes the recent trends of the a and its recent application in the field.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.2
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• pp.39-45
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• 1999

In case of field weakening region, torque is directly affected by flux. In this region, the flux reference is cIecreased inversely proportional to the rotor speed. As the flux is decreased, the magnetizing inductance is nonnally increased The increased magnetizing inductance limited voltage for controlling current In this paper, rreasuring q axis voltage in field weakening region, magnetizing inductance in flux calculating can be readjusted. Computer simulation and experiment results demostrate the efficacy of the prqx>sed rrethod. Proposed algorithm is expected to the application of the adjustable drive system in the spinning and weaving field. field.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.171-176
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• 2010

This paper presents the electric field for 22.9[kV]/380[V], 2[MVA] mold transformer are analysed using FEM(finite element method). The electric field was calculated for the voltage applied to the transformer. Then, it is analysed that the maximum electric field occurred between high voltage turns. Capacitance is calculated with energy method. Surge impulse test simulation is studied by modeling circuit with capacitance and inductance. This paper obtain the result that is about influence of electric field in distribution mold transformer adopted.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.512-519
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• 2000

The discharge capacity of vertical drains installed in the field is reduced with time elapsed after installation due to deformation of drains and clogging effect. Discharge capacity of two types of vertical drains was analysed about three years after installation in the subsoil. Discharge capacity of two types of vertical drains were measured by small, middle, and large scale test apparatus. The results indicate that the discharge capacity of vertical drains after three years operation dramatically decreased compare to the initial discharge capacity.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.3
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• pp.51-56
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• 2001

In this paper, the effect of magnetic field on corona discharge phenomena was experimentally investigated in the needle-plate electrode geometry. Needle-plate geometry discharge system with magnetic field at a right angle to the electric field was made. The corona discharge characteristics with magnetic field were investigated and compared with the corona characteristics without magnetic field in atmospheric pressure. As a result, in case of positive DC corona discharge with magnetic field, corona discharge zone was significantly wider, corona current was lower, and breakdown voltage was higher than those without magnetic field. However, in case of negative DC corona discharge with magnetic field, corona current was slightly higher and breakdown voltage was lower than those without magnetic field. It is thought that this result is due to cyclotron motion of charged particles such as electron and ion by magnetic field.