• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.1
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• pp.31-38
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• 2004

PMN-PT, a piezoelectric single crystal, has many useful applications such as sensors and actuators. In this paper, all the elastic, piezoelectric, and dielectric constants of the PMN-32％PT single crystals were measured by the resonance method. For the rhombohedral symmetry, a total of twelve independent material constants were measured such as six elastic compliance constants at constant electric field, two dielectric constants at constant stress, and four piezoelectric constants d. Seven sets of crystal samples of each different geometry were prepared for the measurement of length-thickness extensional, thickness extensional, radial, length extensional and thickness shear modes of vibration, respectively. In order to check the validity of the measurement, experimental impedance spectrum of the PMN-PT crystal was compared with numerical data spectrum calculated with the measured material constants. The good agreement between the two spectra confirmed validity of the results in this paper.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.3
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• pp.266-281
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• 2017

Hydroelastic interactions of a deformable floating body with random waves are investigated in time domain. Both hydroelastic motion and structural dynamics are solved by expansion of elastic modes and Fourier transform for the random waves. A direct and efficient structural analysis in time domain is developed. In particular, an efficient way of obtaining distributive loads for the hydrodynamic integral terms including convolution integral by using Fubini theory is explained. After confirming correctness of respective loading components, calculations of full distributions of loads in random waves are expedited by reformulating all the body loading terms into distributed forms. The method is validated by extensive convergence tests and comparisons against the counterparts of the frequency-domain analysis. Characteristics of motion/deformation responses and stress resultants are investigated through a parametric study with varying bending rigidity and types of random waves. Relative contributions of componential loads are identified. The consequence of elastic-mode resonance is underscored.

• Journal of KSNVE
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• v.10 no.4
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• pp.662-668
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• 2000

Sound transmission characteristics are investigated on the aluminium extruded panels used for railway vehicles. An equivalent orthotropic plate model and mass law are applied to predict the sound transmission loss. An extruded panel specimen used in the floor of railway vehicles is manufactured and is tested to measure sound transmission loss by two reverberant chamber method. Predicted transmission loss I compared with measured values and the effect of local resonance on the transmission characteristics is identified. The results are applied to design the extruded panel having better sound insulation performance.

• Journal of the Korean Magnetic Resonance Society
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• v.2 no.1
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• pp.50-58
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• 1998

The systematic chirality investigations were made on the basic of the fact that zinc-binding tallysomycin (ZnTLMA) could have chiral centers (Zn, NC3, C6) at possible 4-, 5-, and 6-coordination models. Although our NMR data exhibit that the ligation sites are ${\beta}$-aminoalanine, ${\beta}$-hydroxyhistidine, and pyrimidine moiety, all possible coordination modes were tested out to see what kind of chiralities on NC3-C6 are favorable to each coordination mode. Tests were also made that take into account the specific configuration of functional groups, including ${\beta}$-aminoalanine, sugar ring, and ${\beta}$-hydroxyhistidine. Tests were finally extended to zinc-water binding and specific conformational studies by introducing various hydrogen bonding networks associated with the propionamide side chain and the carbamide group of mannose. Results of systematic chirality investigations exhibit that the S-S configuration of NC3-C6 is favorable to all of coordination models, but the R-S configuration, if exists at all, should have internal strain on C6 chiral center.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1096-1103
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• 1990

A finite element method is used for analyzing the resonant characteristics of three- dimensional wind tunnel with circular cross section. The resonant frequencies of wind tunnel is nearly constant in Mach number range of 0.0-0.2. The resonant frequencies and modes of three-dimensional low speed wind tunnel have been calculated. The 20-node isoparametric element gives accurate results compared with the experimental results.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.3
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• pp.136-141
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• 2000

This paper presents the design of an H$\infty$ based robust Static Synchronous Compensator (STATCOM) supplementary controller to suppress the subsynchronous resonance (SSR) in the series-compensated system. The IEEE second benchmark, System-l model is employed for this study. In order to design the effective controller, the modal controllability and observability indices to the oscillation modes are considered. Comprehensive time domain simulations using a nonlinear system model that the proposed STATCOM supplementary controller can suppress the SSR efficiently in spite of the variations of power system operating conditions.

• Nuclear Engineering and Technology
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• v.50 no.7
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• pp.1106-1111
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• 2018

Electromagnetic waves potentially have been used to heat overdense nuclear fusion plasmas through a double mode conversion from ordinary to slow extraordinary and finally to Electron Bernstein Wave (EBW) modes, OSXB. This scheme is efficient and has not any plasma density limit of electron cyclotron resonance heating due to cut-off layer. The efficiency of conversion depends on the isotropic launching angles of the microwaves with the plasma parameters. In this article, a two-step mode conversions of OSXB power transmission efficiency affected by the fast extraordinary (FX) loses at upper hybrid frequency are studied. In addition, the kinetic (hot) dispersion relation of a overdense plasma in a full wave analysis of a OSXB in Wendelstein 7X (W7-X) stellarator plasma has been numerically simulated. The influence of plasma dependent parameters such as finite Larmor radius, electron thermal velocity and electron cyclotron frequency are represented.

• Geomechanics and Engineering
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• v.32 no.5
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• pp.541-551
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• 2023

Snap-buckling is one of the main failure modes of structures, because it will lead to the reduction of structural bearing capacity, durability loss and even structural damage. Boundary condition plays an important role in the research of engineering mechanics. Further discussion on the boundary conditions problems will help to analyze the dynamic and static behavior of structures more accurately. Therefore, in order to understand the dynamic and static behavior of curved beams more comprehensively, this paper mainly studies the nonlinear snap-through buckling and forced vibration characteristics of functionally graded graphene reinforced composites (FG-GPLRCs) curved beams with two different boundary conditions (including clamped-hinged and hinged-hinged) using Euler-Bernoulli beam theory (E-BBT). In addition, the effects of the curved beam radius, the GLPs distributions, number of GLPs layers, the mass fraction of GLPs and elastic foundation parameters on the nonlinear snap-through buckling and forced vibration behavior are discussed respectively.

• Current Optics and Photonics
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• v.4 no.2
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• pp.134-140
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• 2020

A significant enhancement of the magneto-optical Faraday rotation and extraordinary optical transmission (EOT) in the cascaded double-fishnet (CDF) structure with periodic rectangular apertures is theoretically predicted by using the extended finite difference time domain (FDTD) method. The results demonstrate that the transmittance spectrum of the CDF structure has two EOT resonant peaks in a broad spectrum spanning visible to near-infrared wavebands, one of them coinciding with the enhanced Faraday rotation and large figure of merit (FOM) at the same wavelength. It is most important that the resonant position and intensity of the transmittance, Faraday rotation and FOM can be simply tailored by adjusting the incident wavelength, the thickness of the magnetic layer, and the offset between two metallic rectangular apertures, etc. Furthermore, the intrinsic physical mechanism of the resonance characteristics of the transmittance and Faraday rotation is thoroughly studied by investigating the electromagnetic field distributions at the location of resonance. It is shown that the transmittance resonance is mainly determined by different hybrid modes of surface plasmons (SPs) and plasmonic electromagnetically induced transparency (EIT) behavior, and the enhancement of Faraday rotation is mostly governed by the plasmonic electromagnetically induced absorption (EIA) behavior and the conversion of the transverse magnetic (TM) mode and transverse electric (TE) mode in the magnetic dielectric layer.

• Journal of Sensor Science and Technology
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• v.26 no.6
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• pp.402-407
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• 2017

Characteristics of various material surface plasmon resonance (SPR) chips were investigated in angular interrogation mode and intensity interrogation mode. Among five metals, silver (Ag), gold (Au), copper (Cu), chromium (Cr) and titanium (Ti), three metals, Ag, Au and Cu were paid attention to since their characteristics can be easily analyzed in angular interrogation mode by investigating the change of their reflectance curves according to refractive index change from 1.331 to 1.335. Most of SPR chips with various configurations showed the similar property in angular interrogation mode. The application of the SPR chip made of Ag, Au and Cu or their combinations depends on their reflectance properties. In intensity interrogation mode, the operation range may be limited since the variation of the intensity was not linearly related to refractive index change ranging from 1.331 to 1.335. However, the SPR chip containing high ratio of Ag may be applicable to high sensitive detection due to their sharp reflectance curves in intensity interrogation mode.