• 한국정밀공학회지
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• 제23권6호
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• pp.160-165
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• 2006

We have designed a high-transmission nano aperture in a perfect electric conductor film with the incident beam of 532 nm wavelength. The aperture basically has a C-shape and is known to produce a bright spot nearby the aperture in small size less than diffraction limit. The bright spot is strongly coupled with the local plasmon excited through the aperture hole. The characteristics of transmission and peak power of the aperture output were calculated using finite differential time domain (FDTD) technique, and the geometry of the aperture was determined to get a maximum transmission and peak power. To find the effect of the surface plasmon induced near by the aperture, we calculated the variations of the transmittance and the beam sizes by changing the size of the input beam irradiated on the aperture.

• 한국전기전자재료학회논문지
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• 제23권6호
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• pp.491-496
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• 2010

The relaxation behavior of aligned electric dipoles in a mixed polymer of P2ANS with P(VDF-TrFE) is studied with optical second harmonic generation (SHG). In this work, a macroscopic noncentrosymmetry of the spin coated film was achieved by an electrical poling. The relaxation of induced polar order of nonlinear optic(NLO) chromophores after poling leads to an insufficient long-term stability of NLO properties. In this work, we develop a new technique to suppress such kind of dipole relaxation in a poled polymer. We found that the poled dipoles in a NLO polymer were effectively immobilized by the internal electric field created by a thermally annealed ferroelectric polymer. The long-term stability in a mixed system of NLO polymer/ferroelectric polymer was successively accomplished by a series of thermal treatments applied to the mixed polymer system at a temperature of $140^{\circ}C$ for at least 1hour after poling.

• Advanced Composite Materials
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• 제16권1호
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• pp.63-81
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• 2007

Based on the Kirchhoff hypothesis of normal-remain-normal, the present work analyses piezoelectric laminated plates, wherein poled piezoelectric laminae are transversely isotropic and function as actuators. A quadric electric field is induced inside a piezoelectric lamina under a given applied voltage and mechanical bending. The governing equations for the piezoelectric laminated plate derived from the principle of virtual work in terms of the electric enthalpy have the same forms as those for a conventional composite laminated plate. We use rectangular sandwich plates of Al/PZT/Al and PZT/Al/PZT with four simply supported edges to demonstrate the prediction of the maximum bending stress in the PZT layer. The analytic solutions are verified by three-dimensional finite element analysis.

• Journal of Magnetics
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• 제16권1호
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• pp.6-9
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• 2011

Spin-motive force has drawn attention because it contains a fundamental physical property. Spin-motive force creates effective electric and magnetic fields in moving magnetization; a vortex is a plausible system for observing the spin-motive force because of the abrupt profile of magnetization. However, the time-averaged value of a spin-motive force becomes zero when a vortex core undergoes gyroscopic motion. By means of micromagnetic simulation, we demonstrates that a non-zero time-averaged electric field induced by spin-motive force under certain conditions. We propose an experimental method of detecting spin-motive force that provides a better understanding of spin transport in ferromagnetic system.

• 센서학회지
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• 제29권1호
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• pp.59-62
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• 2020

Currently, increasing attention is being paid to relaxor-based ferroelectric single crystals in photoacoustic images, especially for high-end applications. Among the crystals are (1-x)Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃ (PMN-100xPT) single crystals located near their morphotropic phase boundary (x = 0.30-0.35) because of their ultrahigh piezoelectric and electromechanical coupling properties. The alternating current poling (ACP) treatment, rather than the conventional direct current poling treatment, has recently been spotlighted due to its effectiveness in enhancing the piezoelectric properties. So far, it has been suggested that the enhanced piezoelectricity originates from either a domain miniaturization to nanodomains or from an electric-field-induced monoclinic symmetry. In this study, we demonstrate by thermally stimulated depolarization current measurements that the effect of ACP is too complex to be explained using a single mechanism and that the proposed electric-field-induced monoclinic symmetry is unlikely to exist.

• 한국전기전자재료학회논문지
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• 제36권5호
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• pp.505-512
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• 2023

This study investigated crystal structures, microstructures, and electric-field-induced strain (EFIS) properties of Bi-based lead-free ferroelectric/relaxor composites. Bi_1/2Na_0.82K_0.18)_1/2TiO₃ (BNKT) as a ferroelectric material and 0.78Bi_1/2(Na_0.78K_0.22)_1/2TiO₃-0.02LaFeO₃ (BNKT2LF) as a relaxor material were synthesized using a conventional solid-state reaction method, and the resulting BNKT2LF powders were subjected to high-energy ball milling (HEBM) after calcination. As a result, HEBM proved a larger average grain size of sintered samples compared to conventional ball milling (CBM). In addition, the increased sintering time led to grain growth. Furthermore, HEBM treatment and sintering time demonstrated a significant effect on EFIS of BNKT/BNKT2LF composites. At 6 kV/mm, 0.35% of the maximum strain (S_max) was observed in the HEBM sample sintered for 12 h. The unipolar strain curves of CBM samples were almost linear, indicating almost no phase transitions, while HEBM samples displayed phase transitions at 5~6 kV/mm for all sintering time levels, showing the highest S_max/E_max value of 700 pm/V. These results indicated that HEBM treatment with a long sintering time might significantly enhance the electromechanical strain properties of BNT-based ceramics.

• 한국안전학회지
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• 제30권5호
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• pp.14-19
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• 2015

This study performed simulation tests to prevent induced lightning that occurs to a 22.9 kV-Y distribution line. A simulated distribution line reduced to 1/50 of an actual distribution line was installed to measure the induced voltage according to the change in grounding resistance. It was found that the induced voltage increased as the grounding resistance increased but that the range of its increase was small. This study examined the reliability of the proposed lightning preventive distribution line using the Minitab program (Minitab 17). When a grounding resistance of $300{\Omega}$ was maintained for each electric pole, the Anderson Darling (AD) was 0.410, the smallest, and the P value was analyzed to be 0.323, verifying that the reliability and stability were excellent. Therefore, these results will be utilized as a basis for the substantiation of a lightning preventive distribution line before its installation.

• 한국전기전자재료학회논문지
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• 제15권10호
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• pp.896-901
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• 2002

The polarization and strain behavior of multilayer ceramic actuators fabricated by tape casting using a PNN-PZT ceramics were investigated in association with electrode size and internal layer number. Spontaneous polarization and strain decreased with increasing electrode size. In addition, the increase of internal layer number brought reduced spontaneous polarization and increased the field-induced strain. Because the actuators structure is designed to stack ceramic layer and electrode layer alternatively, the ceramic-electrode interfaces may act as a resistance to motion of domain wall. To analyze the effect of ceramic-electrode interface, the diffraction intensity ratio of (002) to (200) planes was calculated from X-ray diffraction patterns of samples subjected to a voltage of 200 V. The diffraction intensity ratio of (002) to (200) planes was decreased with increasing electrode size and internal layer number. The diffraction intensity ratio and straining behavior analyses indicate that the Polarization and strain were affected by the amount of 90°domain decreasing with increasing electrode size and internal layer number. Consequently, the change of polarization and displacement with respect to electrode size and layer number is likely to be caused by readiness of the domain wall movement around the interface.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2011년도 한국우주과학회보 제20권1호
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• pp.29.3-29.3
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• 2011

The turbulence in the nonlinear regime of the electromagnetic ion-cyclotron (EMIC) instability are investigated via a particle-in-cell (PIC) simulation. EMIC instability arises from anisotropic ion temperature and excites the Alfven ion-cyclotron (AIC) waves. The excited AIC waves undergo inverse-cascade via the nonlinear wave interaction of two AIC and one ion density modes. Induced ion density modes are the normal and second harmonic ion-acoustic (IA) waves. They have the same group velocity, but the second harmonic IA mode only generates the longitudinal electric field.

• 한국응용과학기술학회지
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• 제19권3호
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• pp.245-249
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• 2002

A (disk-like liquid crystal (DLC) monomer/liquid crystals(LCs)/chiral dopant/dichroic dye) composite was irradiated with ultraviolet (UV) light. The (DLC network/LCs/chiral dopant/dichroic dye) was formed in the homeotropically oriented smectic A(SA) phase by the surface orientation treatment and the electric field. A focal-conic texture exhibiting strong light scattering appeared in the heat-induced chiral nematic phase(N${\ast}$) of the composite upon heating. Thermo-recording in the composite system has been realized by using a He-Ne laser. The laser irradiation was induced the phase transitions from SA phase to chiral nematic(N${\ast}$) phase in the composite system.