• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.161-162
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• 2008

The steady state performance test for the digital protective relay using general relay test equipment has been main test methods. Because of the development of advanced power system testing equipments, dynamic performance test has been carried out additionally using a digital simulator such as RTDS(Real Time Digital Simulator). For the case of newly adopted digital protective relay with IEC 61850 and network, performance testing items need supplementing. This report displays testing items change according to newly protective relay.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.854-855
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• 2008

This paper deals with the computation error produced in the time step analysis for a electric machine with eddy current. To investigate the error in quantity, the analytic equations representing the steady state results of time-step analysis are deduced. Using the equations, the characteristics of errors are calculated for a general electric circuit, with variation of the circuit parameters and step size.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1271-1273
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• 1994

In the field of the optics, precise machine, semiconducting processing, the micro-positioning actuators are required for the control of position in the submicron range. In this study, PNN-PZN-PZT ceramics were fabricated by solid state reaction. The structural, dielectric and electric properties were investigated for sintering condition. The specimen sintered for 1hr at 1,150($^{\circ}C$), had the highest density and dielectric contant.

• Journal of Sensor Science and Technology
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• v.8 no.3
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• pp.211-218
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• 1999

This paper describes the application of a coupled finite element-boundary element method (FE-BEM) to obtain the steady-state response of a piezoelectric transducer. The particular structure considered is a PZT4 disc-typed projector. The projector is three-dimensionally simulated to transduce applied electric charge on axial surfaces of the piezoelectric disc to acoustic pressure in air or in water. The directivity pattern of the acoustic field formed from the projected sound pressure is also simulated. And the displacement of the disc caused by the externally applied electric charge is shown in temporal motion. The coupled FE-BE method is described in detail.

• Journal of Electrical Engineering and Technology
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• v.11 no.5
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• pp.1242-1252
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• 2016

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.99-102
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• 2006

We developed the electronic ballast for the street HID lames with the leakage current detection and circuit breaker function. By detecting the leakage current and breaking the system we are protected from the electric shock and the ballast is safe from the electric damage at the time of the continuous reignition state.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1786-1795
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• 2015

It is common practice to identify the insulation faults of GIS through monitor the contents of SF₆ decomposed components. Partial discharges (PD) could lead to the decomposition of SF₆ dielectric, so new reactions usually occur in the mixture of the newly decomposed components including traces of H₂O and O₂. The new reactions also cause the decomposed components to differ due to the different amounts of H₂O and O₂ even under the same strength of PD. Thus, the accuracy of assessing the insulation faults is definitely influenced when using the concentration and corresponding change of decomposed components. In the present research, a needle-plate electrode was employed to simulate the PD event of a metal protrusion insulation fault for two main characteristic components SO₂F₂ and SOF₂, and to carry out influence analysis of trace H₂O and O₂ on the characteristic components. The research shows that trace H₂O has the capability of catching an F atom, which inhibits low-sulfide SF_x from recombining into high-sulfide SF₆. Thus, the amount of SOF₂ strongly correlates to the amount of trace H₂O, whereas the amount of SO₂F₂ is weakly related to trace H₂O. Furthermore, the dilution effect of trace O₂ on SOF₂ obviously exceeds that of SO₂F₂.

• Journal of Biomedical Engineering Research
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• v.23 no.5
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• pp.405-412
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• 2002

The principle of Acupuncture effect on meridians is what physical stimulation does on general physiology so that is gets into new equilibrium from the fallen function state of human body. However, in western medicine, it is generally accepted that the action passageway of various kinds stimulation has been regarded as nerve-endocrine-immune system. Acupuncture effect has been regarded any action for all meridians as a respones by the stimulation. Western medicine doesn's accept treatment for transmission of the bio-energy. In this paper, we compared change of electric potential when an acupuncturist's bio-energy is passed on and when is not. As a result of clinics, the acupuncture effect is different as acupuncture method, when an acupuncturist's bio-energy is passed on the meridian and it isn's. It implies that acupuncture effect can complicately respond by simple acupuncture stimulus and transmission of bio-energy, on same meridian. We could confirm the relationship between an acupuncturist's energy transmission and acupuncture effect. Therefore, we could diagnosis the state of meridian using change of electric potential on the same meridian.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.1917-1926
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• 2018

In view of the current state of the reserves of electric energy generated resources and the share of electric motors in electricity consumption, many researches and studies related to efficiency in electric motors are being made. The presented work is related to the Axial Flux Permanent Magnet Synchronous Motor (AF-PMSM), which has recently undergone significant work based on the development of magnet and motor technology. In this study, a novel AF-PMSM was designed analytically through Finite Element Method (FEM) which can be started by connecting to a line such as an asynchronous motor in a transient state and can operate with high efficiency and power factor after synchronization in steady state without the need for an expensive motor drive. According to the obtained FEM results, a design with an efficiency class of IE4 of 5.5 kW shaft power, a 4 poles motor was obtained. As a result, economic calculations indicate that the extra cost of the designed Line start AF-PMSM with respect to the asynchronous motor is rapidly compensated by energy saving due to a more efficient operation, especially constant speed operations. As a result of the analysis obtained, the targeted values are reached. For induction motors and radial flux permanent magnet synchronous motors, a good alternative motor that can operate with high efficiency and power factor has been obtained.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1682-1691
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• 2018

Natural ester is a suitable substitute for mineral oil and has been widely used in AC transformer in many countries. In order to further application of natural ester in direct current (DC) equipment, it is needed to investigate its long term insulation property under DC condition. In this paper, a thermal ageing experiment was conducted for both mineral oil-paper and natural ester-paper insulation. The DC breakdown and space charge characteristics of insulation paper impregnated with natural ester and mineral oil was compared. Results show that the resistivity of the paper immersed in natural ester and mineral oil both increase as the ageing goes on. While insulation paper impregnated with natural ester has higher resistivity and DC breakdown voltage than the paper impregnated with mineral oil. The DC breakdown voltage for the oil impregnated insulation paper being DC pre-stressing is higher than that without pre-stressing. The average DC breakdown field strength difference between the test with pre-stressing and without pre-stressing clearly shows that there is an apparent enhancement effect for the homo-charge injection on the DC breakdown.