• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.214-217
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• 2007

This paper presents a reduction method of penetrated electromagnetic fields through a narrow slot with resistive sheet in a planar conducting screen of infinite extent. When a plane wave is excited to the narrow slot, the aperture electric field is controlled by the parallel plates connected on the slot. The magnitude of penetrated electromagnetic fields through the narrow slot is controlled by the electric field distribution on the slot. The results show that the magnitude of the penetrated electromagnetic field can be effectively reduced by installing the resistive plates on the slot.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.249-251
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• 2005

A method of double-pole construction is developing to strengthen the mechanical intensity of the electric poles. Therefore the mechanical properties of the double-pole were researched in this paper. First, considering field special quality electric poles were established. In the next tensile force was applied and stress distribution and fatigue load were examined. When a base of the pole is concrete, mechanical intensity of the double-pole increased about 1.7 times compared a single pole.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.4
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• pp.826-834
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• 1994

The purpose of this study is to identify torque characteristics in capacitor type electric motors and to illustrate the effects of several design parameters on the fluctuating components of the motor torque. To do this, two revolving field theory and stationary reference frame theory were applied to derive governing equations for the torque generated by motor. For simulation studies, parameters of the motor components were measured under the conditions of no loading and locking. Based on these, effects of several design variables on the torque characteristics were analyzed and compared with the actual measurements, which were estimated indirectly by measuring the stator voltage and current. Then, some illustrative improvements in design are suggested by taking Taguchi method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.64-64
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• 2009

Atomic force microscopy (AFM) fabrication of oxide patterns is an attractive technique for nanoscale patterns and related device structures, SiC exhibits good performance in high-power, high-frequency, and high-temperature conditions that is comparable to the performance of Si. The AFM fabrication of oxide patterns on SiC is important for electronic applications. However, there has not been much reported investigations on oxidation of SiC using AFM. We achieved the local oxidation of 4H-SiC using the high loading force of ~100 nN, although the oxidation of SiC is generally difficult mainly due to the physical hardness and chemical inactivity. All the experiments were performed using atomic force microscopy (S.I.S. GmbH, Germany) with a Pt/Ir-coated Si tip at ~40% humidity and room temperature. The spring constant and resonance frequency of the tip were around ~3 N/m and ~70 kHz. We fabricated oxide patterns on n-type 4H-SiC ($\sim10^{19}/cm^3$) and n-type Si ($\sim1.9\times10^{16}/cm^3$). In summary, we demonstrated that the oxide patterns can be obtained over the electric field of ${\sim}\times10^7 V/cm$ and the high loading force using the tip as a cathode. The electric field transports the oxyanions (OH-) to the positively biased surface.

• Journal of Astronomy and Space Sciences
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• v.17 no.1
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• pp.87-98
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• 2000

We examine the relative contributions of the electric field and ionospheric conductance to the auroral electrojets. For this purpose we used magnetometer data obtained from the International Magnetospheric Study (IMS) meridian chains of observatories for March 17, 18, and 19, 1978. Based on the study by Allen & Kroehl (1975), we redefine the AU and AL indices by utilizing the magnetic disturbance data obtained from the AE stations located within limited magnetic local time (MLT) sectors; i.e., $1500\leq MLT\leq1800$ and$0000\leq MLT\leq0300$, respectively. The current densities of the eastward and westward electrojets are calculated based on the AU and AL indices thus defined. Under the assumption that the Hall conductance at the dusk sector is mainly caused by the solar EUV radiation, we estimate the electric field contributin to the AU index. Assuming further that electric field distributins at dawn and dusk sectors are comparable, it is also possible to estimate the contribution of the Hall conductance associated at the dusk sector is mainly caused by the solar EUV radiation, we estimate the electric field contribution to the AU index. Assuming further that electric field distributions at dawn and dusk sectors are comparable, it is also possible to estimate the contribution of the Hall conductance associated with auroral particle precipitation to the AL index. From this study it is noted that the electric fields and Hall conductances thus estimated show significant correlations with the AU and AL indices, respectively, suggesting that the AU and AL indices are closely associated with the directly driven and loading-unloading processes of substorms.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.5
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• pp.183-188
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• 2004

A method of double-pole construction is developing to strengthen the mechanical intensity of the electric poles. Therefore the mechanical properties of the double-pole were researched in this paper. First, considering field special quality electric poles were established. In the next tensile force was applied and stress distribution and fatigue load were examined. When a base of the pole is concrete, mechanical intensity of the double-pole increased about 1.7 times compared a single pole. In the case of general soil base, the concrete base should be needed to expect the reinforcement effect of the double-pole.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.1
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• pp.61-65
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• 2010

A commercially available soft PZT wafer that is poled in thickness direction is subjected to longitudinal tensile stress loading in both short and open-circuit conditions. Variations of electric displacement in thickness direction and in-plane strains are measured over time during the loading. Different material responses in the two electrical boundary conditions are explained by the effects of piezoelectrically produced internal electric field on linear material moduli and domain switching mechanisms. Finally, a free energy model of normal distribution is introduced to explain the observed creep behavior, and its predictions are compared with experimental observations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.10
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• pp.831-835
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• 2008

We present a continuous electrical cell lysis chip, using a DC bias voltage to generate the focused high electric field for cell lysis as well as the electroosmotic flow for cell transport. The previous cell lysis chips apply an AC voltage between micro-gap electrodes for cell lysis and use pumps or valves for cell transport. The present DC chip generates high electrical field by reducing the width of the channel between a DC electrode pair, while the previous AC chips reducing the gap between an AC electrode pair. The present chip performs continuous cell pumping without using additional flow source, while the previous chips need additional pumps or valves for the discontinuous cell loading and unloading in the lysis chambers. The experimental study features an orifice whose width and length is 20 times narrower and 175 times shorter than the width and length of a microchannel. With an operational voltage of 50 V, the present chip generates high electric field strength of 1.2 kV/cm at the orifice to disrupt cells with 100% lysis rate of Red Blood Cells and low electric field strength of 60 V/cm at the microchannel to generate an electroosmotic flow of $30{\mu}m/s{\pm}9{\mu}m/s$. In conclusion, the present chip is capable of continuous self-pumping cell lysis at a low voltage; thus, it is suitable for a sample pretreatment component of a micro total analysis system or lab-on-a-chip.

• Smart Structures and Systems
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• v.15 no.6
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• pp.1411-1437
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• 2015

The electro-magneto- thermo-elastic behavior of a rotating functionally graded long hollow cylinder with functionally graded piezoelectric (FGPM) layers is analytically analyzed. The layers are imperfectly bonded to its inner and outer surfaces. The hybrid cylinder is placed in a constant magnetic field subjected to a thermo-electro-mechanical loading and could be rested on a Winkler-type elastic foundation. The material properties of the FGM cylinder and radially polarized FGPM layers are assumed to be graded in the radial direction according to the power law. The hybrid cylinder is rotating about its axis at a constant angular velocity. The governing equations are solved analytically and then stresses, displacement and electric potential distribution are calculated. Numerical examples are given to illustrate the effects of material in-homogeneity, magnetic field, elastic foundation, applied voltage, imperfect interface and thermo-mechanical boundary condition on the static behavior of a FG smart cylinder.

• Structural Engineering and Mechanics
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• v.60 no.2
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• pp.271-299
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• 2016

In this article, based on the higher-order shear deformation plate theory, buckling analysis of a rectangular plate made of functionally graded piezoelectric materials and its effective parameters are investigated. Assuming the transverse distribution of electric potential to be a combination of a parabolic and a linear function of thickness coordinate, the equilibrium equations for the buckling analysis of an FGP rectangular plate are established. In addition to the Maxwell equation, all boundary conditions including the conditions on the top and bottom surfaces of the plate for closed and open circuited are satisfied. Considering double sine solution (Navier solution) for displacement field and electric potential, an analytical solution is obtained for full simply supported boundary conditions. The accurate buckling load of FGP plate is presented for both open and closed circuit conditions. It is found that the critical buckling load for open circuit is more than that of closed circuit in all loading conditions. Furthermore, it is observed that the influence of dielectric constants on the critical buckling load is more than those of others.