• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.4
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• pp.62-68
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• 2015

Subsynchronous Resonance is a condition where the electrical power systems composed of generator and transmission line exchange energy with mechanical turbine-generator system at the frequency of the combined below the subsynchronous frequency. Therefore, the frequency of power systems should be associated with the subsynchronous resonance. This paper describes subsynchronous resonance by flexible frequency operation. It focuses on the characteristics and behavior of subsynchronous resonance. The subsynchronous resonance is being conducted by real-time digital simulator and the IEEE benchmark model for subsynchronous resonance have been utilized for the test systems.

• Nuclear Engineering and Technology
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• v.33 no.1
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• pp.46-61
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• 2001

The neutron cross sections of $^{160}$ Dy, $^{161}$ Dy, $^{162}$ Dy, $^{l63}$Dy, and $^{164}$ Dy have been evaluated in the resonance region of which upper energy is set to several tens of keV. The cross sections are formulated with resonance parameters in the energy region under consideration. In the resolved resonance region, the positive-energy resonance parameters were adopted from the BNL compilation published in 1984 with slight, if any, modifications. A bound level resonance for each isotope except $^{162}$ Dy was invoked to reproduce the reference 2200 m/s cross sections and the bound coherent scattering length. Subsequently, the statistical behavior of the resolved resonance parameters was analyzed, and thus obtained s-wave average parameters were adopted in the unresolved resonance region. In addition, recent measurements of the capture cross sections in the unresolved region were taken into account in adjusting the average resonance parameters for high orbital angular momentum resonances. The present evaluation resulted in large improvements in the cross sections over the ENDF/B-Vl release 6.6.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3202-3218
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• 1994

Mode shapes and natural frequencies of vibrating laminated composite plates are taken using real-time and time-average holographic interferometry. Debonds and delamination in the laminated plates are measured nondestructively. During holographic testing of composite plates, it has been found that the conditions for the local resonance in debonds are strongly dependent on the frequency of excitation. A membrane resonance model was proposed to describe this behavior. Relations between characteristic length according to the size, shape of debonds and membrane resonance frequency are presented. Several experiments were performed to verify the membrane resonance model. The agreements between the predicted excitation frequency and the observed resonance frequency are good. The experimental results show that higher stresses and strains due to local resonance lead to the debond detection.

• Journal of Magnetics
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• v.17 no.4
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• pp.255-260
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• 2012

In this study, we determine that the electron paramagnetic resonance line-width (EPRLW) is axially symmetric about the c-axis and analyze the spin Hamiltonian with an isotopic g-factor of 1.9920 at a frequency of 9.5 GHz. It should be noted that the electron paramagnetic resonance signals are Lorentzian. Our findings show that the EPRLW decreases exponentially with an increase in the temperature; i.e., its temperature dependence in the range 300-400 K obeys Arrhenius behavior, this kind of temperature dependence indicates an off-center a motional narrowing of the spectrum when $Mn^{2+}$ impurity ions substitute for $Nb^{5+}$ ions. The specific heats follow a linear dependence suggesting a simple Debye $T^3$ behavior.

• Steel and Composite Structures
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• v.36 no.2
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• pp.179-186
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• 2020

In this paper, the forced resonance vibration of porous functionally graded (FG) curved nanobeam is examined. In order to capture the hardening and softening mechanisms of nanostructure, the nonlocal strain gradient theory is employed to build the size-dependent model. Using the Timoshenko beam theory together with the Hamilton principle, the equations of motion for the curved nanobeam are derived. Then, Navier series are used in order to obtain the dynamical deflections of the porous FG curved nanobeam with simply-supported ends. It is found that the resonance position of the nanobeam is very sensitive to the nonlocal and strain gradient parameters, material variation, porosity coefficient, as well as geometrical conditions. The results indicate that the resonance position is postponed by increasing the strain gradient parameter, while the nonlocal parameter has the opposite effect on the results. Furthermore, increasing the opening angle or length-to-thickness ratio will result in resonance position moves to lower-load frequency.

• Structural Engineering and Mechanics
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• v.86 no.3
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• pp.361-371
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• 2023

Boundary condition is an important factor affecting the vibration characteristics of structures, under different boundary conditions, structures will exhibit different vibration behaviors. On the basis of the previous work, this paper extends to the nonlinear resonance behavior of axially moving graphene platelets reinforced metal foams (GPLRMF) plates with geometric imperfection under different boundary conditions. Based on nonlinear Kirchhoff plate theory, the motion equations are derived. Considering three boundary conditions, including four edges simply supported (SSSS), four edges clamped (CCCC), clamped-clamped-simply-simply (CCSS), the nonlinear ordinary differential equation system is obtained by Galerkin method, and then the equation system is solved to obtain the nonlinear ordinary differential control equation which only including transverse displacement. Subsequently, the resonance response of GPLRMF plates is obtained by perturbation method. Finally, the effects of different boundary conditions, material properties (including the GPLs patterns, foams distribution, porosity coefficient and GPLs weight fraction), geometric imperfection, and axial velocity on the resonance of GPLRMF plates are investigated.

• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.121-127
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• 2007

Muscle force produced by muscle fibers is transmitted to bones via tendinous structures(aponeuroses and tendon), resulting in joint(s) movement. As force-transmitting elements, mechanical behavior of aponeuroses and tendon are closely related with the function of muscle-tendon complex. The purpose of this study was to determine strain characteristics of aponeuroses for in-vivo human soleus muscle during submaximal voluntary contractions using an advanced medical imaging technique, velocity-encoded phase-contrast magnetic resonance imaging (VE-PC MRI). VE-PC MRI of the soleus muscle-tendon complex was acquired during submaximal isometric plantarflexion contraction-relaxation cycle (n = 7), using 3.0T Trio MRI scanner(Siemens AG, Malvern, MA). From the VE-PC MRI containing the tissue velocity in superior-inferior direction, twenty regions of interest(20 ROI; 10 on the anterior aponeurosis and 10 on the posterior aponeurosis) were tracked. During the isometric plantarflexion contraction-relaxation cycle, velocity and displacement profiles were different between the anterior and posterior aponeuroses, indicating heterogeneous strain behavior along the length of the leg. The anterior aponeurosis elongated while the posterior aponeurosis shortened during the initial phase of the contraction. Moreover, strain behavior of the posterior aponeurosis was different from that of the Achilles tendon. Possible explanation for the observed variations in strain behavior of aponeuroses was investigated with morphological assessment of the soleus muscle and it was found that the intramuscular tendinous structures significantly vary among subjects. In conclusion, the heterogeneous mechanical behavior of the soleus aponeuroses and the Achilles tendon suggests that the complexity of skeletal muscle-tendon complex should be taken into consideration when modeling the complex for better understanding of its functions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.833-838
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• 2003

The problem of elastic wave resonance scattering from elastic targets is studied in this paper. A new resonance formalism to extract the elastic resonance information of the target from scattered elastic waves is introduced. The proposed resonance formalism is an extension of the works developed for acoustic wave scattering problems by the author. The classical resonance scattering theory computes reasonable magnitude information of the resonances in each partial wave, but the phase behaves in somewhat irregular way, therefore, is not clearly explainable. The proposed method is developed to obtain physically meaningful magnitude and phase of the resonances. As an example problem, elastic wave scattering from an infinitely-long elastic cylinder was analyzed by the proposed method and compared to the results by RST. In case of no mode conversion, both methods generate identical magnitude. However, the new method computes exact $\pi$ radian phase shills through resonances and anti-resonances while RST produces physically unexplainable phases. In case of mode conversion, in addition to the phase even magnitudes are different. The phase shifts through resonances and antiresonances obtained by the proposed method are not exactly $\pi$ radians due to energy leak by mode conversion. But, the phases by the proposed method show reasonable and intuitively correct behavior compared to those by RST.

• Earthquakes and Structures
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• v.22 no.4
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• pp.373-386
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• 2022

The development of performance-based design methodologies requires a reasonable definition of a displacement-response spectrum. Although ground motions are known to be significantly affected by the resonant-like amplification behavior caused by multiple wave reflections within the surface soil, such a soil-resonance effect is seldom explicitly considered in current-displacement spectral models. In this study, an analytical approach is developed for the construction of displacement-response spectra by considering the soil-resonance effect. For this purpose, a simple and rational equation is proposed for the response spectral ratio at the site fundamental period (SRTg) to represent the soil-resonance effect based on wave multiple reflection theory. In addition, a bilinear model is adopted to construct the soil displacement-response spectra. The proposed model is verified by comparing its results with those obtained from actual observations and SHAKE analyses. The results show that the proposed model can lead to very good estimations of SRTg for harmonic incident seismic waves and lead to reasonable estimations of SRTg and soil displacement-response spectra for earthquakes with a relatively large magnitude, which are generally considered for seismic design, particularly in high-seismicity regions.

• Journal of Magnetics
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• v.13 no.1
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• pp.23-29
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• 2008

The magnetic and other physical characteristics of $Mn_xSi_{1-x}Te$ have been investigated by electron magnetic resonance (EMR), X-ray diffraction (XRD) and other experiments. $Mn_xSi_{1-x}Te$ is found to have corundum structure for manganese contents up to 10% and also to be ferromagnetic for temperatures below 80 K. While ferromagnetic resonance signal coexists with the usual paramagnetic resonance signal, invariance of the g-factor inferred from the electron paramagnetic resonance signals throughout all temperature ranges clearly confirms that the manganese ions are in the electronic 3d5 state. The temperature dependence of EMR line-width is the same as other diluted magnetic semiconductors. From the EMR signals relaxation times $T_2$ and $T_1$ of $Mn_xSi_{1-x}Te$ compounds are estimated to be about $4.4{\times}10^{-10}s$ and $9.3{\times}10^{-8}s$ respectively and are found to vary slightly with temperature or composition change. Exchange narrowing of the EMR line-width becomes dominant for the sample in which the substitution ratio, x = 30%. For one sample, in which x = 0.5%, spin glass-like behavior is indicated by EMR signals for temperatures lower than 60 K. This behavior may authentic for samples within a certain range of x.