• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.11B no.3
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• pp.59-63
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• 2001

This paper presents a new modeling of the two dimensional magnetic property in soft magnetic materials for the magnetic field computations. In this modeling an approximate treatment is introduced to expand the applicable exciting frequency range. The result shows that the new modeling presented here is very useful in simplicity of magnetic field analysis.

• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2262-2267
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• 2017

A new force expression on dielectrics subjected to electric field is proposed in this paper. It is the electric version of the equivalent magnetizing current method in magnetic field. From the idea of electromagnetic duality, virtual equivalent electrifying magnetic current method is conjectured in the field of dielectric force problem. Numerical results show that the proposed method has good agreements with the conventional methods. The merits and demerits of the proposed method are also discussed.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.2001-2006
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• 2017

This paper explains the effects of the weak signal of a rotating-type electric field mill sensor fabricated for measuring the intensity of the electric field generated by high-voltage direct current (HVDC) power transmission lines. The fabricated field mill consists of two isolated electrode vanes, a motor driver, and a ground part. The sensor plate is exposed to and shielded from the electric field by means of a rotary shutter consisting of a motor-driven mechanically complementary rotor/stator pair. When the uncharged sensor plate is exposed to an electric field, it becomes charged. The rotating electrode consists of several conductive vanes and is connected to the ground part, so that it is shielded. Determining the appropriate design variables such as the speed of the vane, its shape, and the distance between the two electrodes, is essential for ensuring optimal performance. By varying the speed, the weak signal characteristics which is used to signal processing and calibration experiment are quite different. Each weak signal pattern was analyzed along with the output voltage characteristics, in order to be able to determine the intensity of the electric field generated by HVDC power transmission lines with accuracy.

• Progress in Superconductivity and Cryogenics
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• v.16 no.1
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• pp.27-31
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• 2014

2G HTS tapes are widely used for various electric machines. In addition, stacked or parallel connected HTS tapes are essentially used to raise transport current level for large capacity electric machines. Therefore, critical current characteristic of stacked tapes need to be studied. Recently developed 2G HTS tapes are fabricated with various defects doping so that tapes possess pinning center to improve the critical current characteristic. During this process, the critical current is determined minimum value in not perpendicular magnetic field but a specific magnetic field angle according to the reported research. However, the effects of magnetic field angle to critical current of multi-stacked 2G HTS tapes have not been examined. In this paper, field coil which is a race-track coil wound by using an HTS tape with iron-core was fabricated to apply angle adjustable magnetic field to the 2G HTS tape samples. We measured critical current of single and multi-stacked two tapes that have different characteristic depending on various magnetic field angle and magnitude in liquid nitrogen environment. Furthermore, results of single and multi-stacked tapes were compared and analyzed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1673-1678
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• 2015

This paper describes magnetic field on power cable in underground transmission systems. Based on specification which is being used in domestic power utility, magnetic field was analyzed in accordance with line arrangement, line burial depth and phase spacing. Magnetic field magnitude and its trend were understood in each circuit type such as double circuits, triple circuits and quadruple circuits of underground transmission systems. In addition, magnetic field was analyzed according to phase arrangement changing in each circuit. Finally, the proper phase arrangement configuration type was suggested by the evaluation of analysis result. Magnetic field was calculated by using Biot-Savart's law. According to the evaluated magnetic fields based on phase layout configuration in each circuit, it figured out that each of magnetic fields was different. As a result, this paper proposes a proper phase layout configuration for generating minimum magnetic field. It is evaluated that the phase layout configuration in each circuit proposed in this paper can be used at actual underground transmission systems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1171-1174
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• 2004

Leakage current of the polymer arrester(42kV, 10kA, Class3) for railroad line applied actually field was observed and electrical characteristics of arrester before and after applied actually field were investigated. During applied actually field, leakage current of arresters were $610{\sim}647{\mu}A$ in AN SAN line and $500{\mu}A$ in YUNG DONG line. After applied actually field, electrical characteristics of arrester, such as insulation test, reference voltage test, leakage current test and partial discharge current test, wasn't variation as before applied actually field.

• Carbon letters
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• v.15 no.3
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• pp.214-217
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• 2014

A filtration-taping method was demonstrated to fabricate carbon nanotube (CNT) emitters. This method shows many good features, including high mechanical adhesion, good electrical contact, low temperature, organic-free, low cost, large size, and suitability for various CNT materials and substrates. These good features promise an advanced field emission performance with a turn-on field of $0.88V/{\mu}m$ at a current density of $0.1{\mu}A/cm^2$, a threshold field of $1.98V/{\mu}m$ at a current density of $1mA/cm^2$, and a good stability of over 20 h. The filtration-taping technique is an effective way to realize low-cost, large-size, and high-performance CNT emitters.

• Korean Journal of Veterinary Research
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• v.33 no.2
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• pp.211-216
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• 1993

To elucidate the action of the cholinergic and ${\alpha}_2$-adrenergic nerve on the isolated ileal smooth muscle of the dog, effect a of electrical field stimulation were investigated on the pretreatment of the physostigmine; cholinestrase inhibitor, yohimbine; ${\alpha}_2$-adrenoceptor blocker, atropine ; cholinergic receptor blocker and phentolamine; non-selective $\alpha$-adrenoceptor blocker from physiograph. 1. The contractile response induced by electrical field stimulation was the frequency (2-40 Hz)-dependent manner. 2. The contractile response induced by electrical field stimulation was markedly increased by the pretreatment of physostigmine$(1{\mu}M)$; cholinestrase inhibitor. 3. The contractile response induced by electrical field stimulation was increased by the pretreatment of yohimbine$(1{\mu}M)$; ${\alpha}_2$-adrenoceptor blocker. These finding suggest that it was powerful excitatory action by cholinergic nerve and inhibitory action by ${\alpha}_2$-adrenergic nerve on ileal smooth muscle of the dog.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.3
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• pp.376-379
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• 2013

Multi-walled carbon nanotubes (MWCNTs) were synthesized using catalytic chemical vapor deposition (CVD) method. Oxygen plasma treatment was applied to modify surface state of the CNTs synthesized for improvement of field emission performance. Surface state of the plasma treated CNTs was studied by X-ray photoelectron spectroscopy (XPS). The surface states of the CNTs were changed as a function of plasma treatment time. The oxygen related carbon shift was moved toward higher binding energy with the plasma treatment time. This result implies that the oxygen plasma treatment changes the surface state effectively. While any shift in carbon 1s peak was not detected for the as grown CNTs, oxygen related carbon shift was detected for the plasma treated CNTs. Carbon shift implies that closed CNT tips were opened by the oxygen plasma and reacted with oxygen species. Since the field emission occurs at pentagons or dangling bonds of the CNT tips, the increase of carbon-oxygen bonds plays an important role in field emission behavior by increasing the number of electron emission sites resulting in improvement of the field emission performance.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.3
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• pp.138-145
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• 2006

It is well known that the accurate calculation of the field distribution is essential for the design of electrical machines. The analytical techniques for electromagnetic field can quickly and exactly determine airgap magnetic field distribution in electrical machines. Many analytical techniques have been investigated to predict the magnetic field distribution in PM machines equipped with permanent magnets. Using the analytical technique by transfer relations, D. L. Trumper and K. R. Davey already presented the design and analysis of linear permanent-magnet machines and induction machines, respectively. Using the transfer relations (Melcher's general methodology) to describe electromagnetic phenomena, this paper deals with the analysis on the magnetic field distribution due to PM and winding current, the induced voltage and the static torque characteristics in surface-mounted slotless type permanent magnet machine. The validity of the analysis results is confirmed by finite element (FE) analysis.