• Journal of IKEEE
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• v.24 no.3
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• pp.713-718
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• 2020

The method of measuring skin active points is a technique for obtaining a lot of biometric information because it is measured with convenience, low cost and non-invasive methods. In this paper, we used in a three electrode measure method that has the advantage of measuring the impedance of the APs under the skin. The impedance measuring method is well illustrated by a simple model of an equivalent electrical circuit that correlates well with experimental results. The characteristic frequencies of APs are about 15-30HZ higher than that of surrounding skin and the values of measured reactance are about 35-77KΩ smaller. This technology analyzed accurately and objectively the reactance and characteristic frequency of APs and the surrounding skin using a non-invasive measuring system.

• Journal of electromagnetic engineering and science
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• v.14 no.2
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• pp.54-60
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• 2014

A systematic design for asymmetric coupled-section Marchand baluns is presented. Asymmetrically coupled transmission lines in multilayer configuration are exploited for constructing Marchand baluns. Design equations for characteristic impedance and electrical length of asymmetrical coupled transmission lines are derived for establishing a systematic design procedure. Novel Marchand balun based on these design equations is composed of two identical asymmetrical coupled transmission lines. However, contrary to the general conventional design approach where ranges for characteristic impedances of coupled lines are ambiguously capitalized, values for characteristic impedance and length are explicitly expressed. Our approach is fundamentally different from the design method using coupling coefficients where solution for coupling coefficient is inherently restricted. To verify the proposed method, one design example is performed for wideband Marchand balun in multilayer configuration, and is fabricated for verifying the design procedure proposed. Maintaining the return loss more than 10 dB, the bandwidth is measured from 0.43 to 1.0 GHz, where $S_{21}$ and $S_{31}$ show better than -4 dB. The measured phase and amplitude imbalances illustrate 0.5 dB and ${\pm}5^{\circ}$, respectively.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.4
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• pp.634-639
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• 2015

In order to understand phenomenon of the electric railway power feeding system in the construction planning step, analysis of the overall system including electric characteristic of electric railway power feeding system, train running characteristic and power consumption pattern and train operation plan and gradients of railroad and curve radius is required. This paper study the feeder system by analysis of comprehensive system according to train operation plans, line impedance, running characteristic of train, electrical properties of the feeder system. In order to understand phenomenon to the feeder system of tram exactly regarding export of the field railroad preceeding actively recently.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.63-65
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• 2004

The recent advancement in the power electronic technique has increased the use of induction motor fed by inverter using high-frequency switching devices. Also the tendency is toward larger size and higher voltage. Therefore, The IGBT (Insulated-Gate Bipolar Transistor) that is high switching frequency element has been using increase. But, The switching surge voltage was occurred by high switching frequency of inverter has appeared a voltage doubling in the motor input terminal due to mismatching of cable characteristic impedance and motor characteristic impedance. Actually, The Switching surge voltage became the major cause to occur the insulation failure by serious voltage stress in the stator winding of induction motor. The short during rise time of switching surge and cable length is increased, the maximum transient voltage seen at the motor terminals increases. In this paper, Analyzed switching surge transient voltage of power cable pulling is used EMTP(Electromagnetic Transient Program) at the induction motor terminal and in cable.

• Journal of electromagnetic engineering and science
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• v.3 no.2
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• pp.104-110
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• 2003

A ring filter is proposed as a wide-banded filter. It consists of a ring and two short stubs, which are connected at 90$^{\circ}$ and 270$^{\circ}$ points of the ring. Since the termination impedance at 90$^{\circ}$ and 270$^{\circ}$ points of the ring and the characteristic impedance of the short stub have an effect on designing of it, the relation between them and bandwidths has been studied. Based on the study, two types of small-sized wideband CVT(constant VSWR-type impedance transformer)- and CCT(constant conductance-type impedance transformer)-ring filters are introduced, designed, simulated and one of two, a CCT -ring filter, is tested. The circumference of the ring can be reduced theoretically up to 60$^{\circ}$ and two of many cases having about 300$^{\circ}$ circumferences are simulated. The simulated results show more than 100 % fractional bandwidth, which can be obtained with more than 5 stages in conventional filter-design techniques. To test the designed CCT-ring filter, it has been fabricated in microstrip technology and the measured results show good agreement with the simulated ones, having more than 100 % fractional bandwidth.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.2
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• pp.80-87
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• 1999

This paper proposed a high impedance fault detection method using a neural network on distribution lines. The $\upsilon-i$ characteristic curve was obtained by high impedance fault data tested in various soil conditions. High impedance fault was simulated using EMTP. The pattern of High Impedance Fault on high density pebbles was taken as the learning model, and the neural network was evaluated on various soil conditions. The average values after analyzing fault current by FFT of even.odd harmonics and fundamental rms were used for the neural network input. Test results were verified the validity of the proposed method .ethod .

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.67-74
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• 2005

Grounding insures a reference potential point for electric devices and also provides a low resistance path for fault currents in the earth. The ground impedance as a function of frequency is necessary for determining its performance since fault currents could contain a wide range of frequencies. In this paper, the ground impedance of Magic rods which are commercially available has been measured in frequency ranging from 0[Hz] up to 100[kHz] and an equivalent circuit model, transfer function model of the ground impedance are identified from the measured values.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.46-51
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• 2005

Grounding insures a reference potential point for electric devices and also provides a low resistance path for fault currents in the earth. The ground impedance as a function of frequency is necessary for determining its performance since fault currents could contain a wide range of frequencies. A cower rod electrode is the most commonly used grounding electrode in electric distribution systems. In this paper, the ground impedance of cower rods has been measured in frequency ranging from 60[Hz] up to 100[kHz] and an equivalent circuit model, transfer function model of the ground impedance are identified from the measured values.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.11
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• pp.1582-1587
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• 2014

In this paper, we perform a modeling for the AT Feeder system in AC electric railway and we utilize the power EMTDC program to implement about AT feeder system modeling. In addition, we study the impedance characteristics of the AT feeder system and calculated fault current and impedance according to the distance due to fault accident. Based on it's result, fault current are compared between calculating the value and simulation value in EMTDC modeling. Impedance of power system is Largest at the middle point of the system and is smallest near autotransformer, and then showed that the fault current is inversely proportional to impedance characteristics.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.4
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• pp.253-260
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• 1999

In this paper, the impedance characteristic of wire-plate pulsed plasma reactor was investigated by experiment. The experiment have carried out under the several conditions of voltage, wire length and wire-plate distance. The impedance of reactor wad decreased with increasing voltage and wire length. The nature of discharge in reactor was changed from streamer corona to spark with increasing incident energy, from which we understood the critical energy density between the two discharges. Fromthis experiment, we proposed the method for the impedance matching between pulse generator and pulsed plasma reactor. Additionally, we succeeded in the analysis ofstray inductance of 0.5MW reactor using EMTP (ElectroMagnetic Transients Program). This means that EMTP is also useful for the analysis of inevitable stray inductance of forthcoming a large scale reactor.