• The Mathematical Education
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• v.55 no.3
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• pp.383-396
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• 2016

This study investigated highschool students' brain waves on functional tasks such as a transition(F task) from equation to graph and the other transition(G task) vice versa. A total of 39 students participated in the study who attended a high school located in Gyunggi province. These students were divided into two groups, HMA and LMA by MASS test revised by Ko, & Yi (2012). The functional tasks for the stroop task to measure EEG were provided from a previous study, Seok(2015). The results indicated two groups on G tasks showed deeper and wider brain waves which demonstrated G tasks were more difficult than F tasks. However, HMA group had an effect of the non-psychological program which had given more chances on G tasks rather than F tasks within Students' Zone of Proximal Development. Also, HMA group's brain waves had more ranges in amplitude and width of waves. These results imply that the characteristics of students' brain waves with math anxiety are consistent to the previous studies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.290-298
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• 2017

This study compared the median nerve, ulnar never, and F waves of patients diagnosed with early Carpal Tunnel Syndrome to a control group to determine whether F waves could be a useful indicator in the diagnosis of early CTS. The terminal motor latency (TML), terminal motor amplitude and sensory nerve conduction velocity (SNCV) of the section from the palms to the wrists, which are the key indicators to use in a nerve conduction study, and F waves were compared with the control group using the t-test. A correlation analysis was performed to analyze the correlation between the main indicators. The comparison between the median nerve's TML of the early CTS patients and that of the control group shows that there are 2 sections which have high significance (p<0.001). In the comparison of the SNCV of the median nerve between the control group and early CTS patients, high significance was observed (p<0.001). In the analysis of the F waves, there was high significance (p<0.001) between the control group and early CTS patients for the median nerve, but not for the ulnar nerve. The correlation analysis revealed that both the SNCV-TML and F wave-TML had significance. These results suggested that, along with TML and SNCV, F waves can be a useful indicator to diagnose CTS.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.1
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• pp.1-10
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• 2011

Nonlinear harmonic waves generated at cracked interfaces are investigated both experimentally and theoretically. A compact tension specimen is fabricated and the amplitude of transmitted wave is analyzed as a function of position along the fatigued crack surface. In order to measure as many nonlinear harmonic components as possible a broadband Lithium Niobate ($LiNbO_3$) transducers are employed together with a calibration technique for making absolute amplitude measurements with fluid-coupled receiving transducers. Cracked interfaces are shown to generate high acoustic nonlinearities which are manifested as harmonies in the power spectrum of the received signal. The first subharmonic (f/2) and the second harmonic (2f) waves are found to be dominant nonlinear components for an incident toneburst signal of frequency f. To explain the observed nonlinear behavior a partially closed crack is modeled by planar half interfaces that can account for crack parameters such as crack opening displacement and crack surface conditions. The simulation results show reasonable agreements with the experimental results.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.6
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• pp.832-837
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• 2007

Many researchers are studying brain activity to using functional Magnetic Resonance Imaging (fMRI), Time Resolved Spectroscopy(TRS), Electroencephalography(EEG), and etc. They are used detection of seizures or epilepsy and deception detection in the main. In this paper, we focus on emotion recognition by recording brain waves. We specially use fMRI, TRS, and EEG for measuring brain activity Researchers are experimenting brain waves to get only a measuring apparatus or to use both fMRI and EEG. This paper is measured that we take images of fMRI and TRS about brain activity as human emotions and then we take data of EEG signals. Especially, we focus on EEG signals analysis. We analyze not only original features in brain waves but also transferred features to classify into five sections as frequency. And we eliminate low frequency from 0.2 to 4Hz for EEG artifacts elimination.

• Science of Emotion and Sensibility
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• v.26 no.4
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• pp.125-132
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• 2023

This study investigated the effects of continuous Singing Bowl healing on brainwaves and autonomic nervous system responses. The variations in brainwaves were measured during 45-minute sessions in eight participants, before and after Singing Bowl healing sessions to assess the changes in brainwaves before and after five weeks of Singing Bowl healing treatment. BioBrain BIOS-S8 was used to obtain brainwave measurements. Electrodes were placed on six channels: F3, F4, T3, T4, P3, and P4. A standard limb lead I with electrodes was used for electrocardiogram (ECG) measurements. Using the collected brainwave data, changes in brain waves were observed before and after five weeks of Singing Bowl healing. Beta waves, alpha waves, and sensorimotor rhythm were found to have reduced, while theta waves, delta waves, and the standard deviation of normal-to-normal intervals in heart rate variability had increased. These results indicate that continuous Singing Bowl healing over five weeks can stabilize brainwaves, activate the autonomic nervous system, and increase the relaxation-inducing effects of the parasympathetic nervous system.

• Journal of The Korean Astronomical Society
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• v.24 no.2
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• pp.129-149
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• 1991

An attempt has been made to examine the characteristics of acoustic and MHD waves generated in stellar convection zones($4000\;K\;{\leq}\;T_{eff}\;{\leq}\;7000\;K$, $3\;{\leq}\;\log\;g\;{\leq}\;4.5$). With the use of wave generation theories formulated for acoustic waves by Stein (1967), for MHD body waves by Musielak and Rosner (1987, 1988) and for MHD tube waves by Musielak et al.(l989a, 1989b), the energy fluxes are calculated and their dependence on effective temperature, surface gravity and megnetic field strength are analyzed by optimization techniques. In computing magneto-convection models, the effect of magnetic fields on the efficiency of convection has been taking into account by extrapolating it from Yun's sunspot models(1968; 1970). Our study shows that acoustic wave fluxes are dominant in F and G stars, while the MHD waves dominant in K and M stars, and that the MHD wave fluxes vary as $T_{eff}^4{\sim}T_{eff}^7$ in contrast to the acoustic fluxes, as $T_{eff}^{10}$. The gravity dependence, on the other hand, is found to be relatively weak; the acoustic wave fluxes ${\varpropto}\;g^{-0.5}$, the longitudinal tube wave fluxes ${\varpropto}\;g^{0.3}$ and the transverse tube wave fluxes ${\varpropto}\;g^{0.3}$. In the case of the MHD body waves their gravity dependence is found to be nearly negligible. Finally we assesed the computed energy fluxes by comparing them with the observed fluxes $F_{ob}$ of CIV(${\lambda}1549$) lines and soft X-rays for selected main sequence stars. When we scaled the corrected wave fluxes down to $F_{ob}$, it is found that these slopes are almost in line with each other.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.205-210
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• 2006

The impact forces of the highly nonlinear waves are one of the important factors in designing the ocean structures. The impact forces are very difficult to analyze numerically and experimentally because they are impulsive in magnitude and occur instantaneously. In this study the numerical program based on N.S. equations are used to investigate the impact forces of steep waves where the waves are gene rated by the wave maker in the numerical wave basin. The arbitrary steep waves are generated by the superposition of waves of single frequency and the impact forces on vertical cylinder are simulated on the multiblock grids. V.O.F. and the local height function methods are used to track the free surfaces. To validate the numerical analysis the numerical results are compared with the experimental ones and the acceptable agreements are found. It is thought that more studies on the simulations of the incoming breaking waves and the impact forces on the vertical cylinder should be made to obtain the useful results to be applied in the offshore design.

• Journal of Biomedical Engineering Research
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• v.7 no.2
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• pp.117-118
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• 1986

It is well known that nonlinear propagation characteristics of the wave in the tissue may give very useful information for the medical diagnoisis. In this paper, a new method to detect nonlinear propagation characteristics of the internal vibration in the tissue for the low frequency mechanical vibration by using bispectral analysis is proposed. In the method, low frequency vibration of f0( = 100Hz) is applied on the surface of the object, and the waveform of the internal vibration x (t) is measured from Doppler frequency modulation of silmultaneously transmitted probing ultrasonic waves. Then, the bispectra of the signal x (t) at the frequencies (f0, f0) and (f0, 2f0) are calculated to estimate the nonlinear propagation characteristics as their magnitude ratio, w here since bispectrum is free from the gaussian additive noise we can get the value with high S/N. Basic experimental system is constructed by using 3.0 MHz probing ultrasonic waves and the several experiments are carried out for some phantoms. Results show the superiority of the proposed method to the conventional method using power spectrum and also its usefulness for the tissue characterization.

• Journal of Astronomy and Space Sciences
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• v.39 no.1
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• pp.11-22
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• 2022

It is suggested that magnetosonic waves (also known as equatorial noise) can scatter radiation belt electrons in the Earth's magnetosphere. Therefore, it is important to understand the global distribution of these waves between the proton cyclotron frequency and the lower hybrid resonance frequency. In this study, we developed an empirical model for estimating the global distribution of magnetosonic wave amplitudes and wave normal angles. The model is based on the entire mission period (approximately 2012-2019) of observations of Van Allen Probes A and B as a function of the distance from the Earth (denoted by L^*), magnetic local time (MLT), magnetic latitude (λ), and geomagnetic activity (denoted by the Kp index). In previous studies the wave distribution inside and outside the plasmasphere were separately investigated and modeled. Our model, on the other hand, identifies the wave distribution along with the ambient plasma environment-defined by the ratio of the plasma frequency (f_pe) to the electron cyclotron frequency (f_ce)-without separately determining the wave distribution according to the plasmapause location. The model results show that, as Kp increases, the dayside wave amplitude in the equatorial region intensifies. It thereby propagates the intense region towards the wider MLT and inward to L^* < 4. In contrast, the f_pe/f_ce ratio decreases with increasing Kp for all regions. Nevertheless, the decreasing aspect differs between regions above and below L^* = 4. This finding implies that the particle energy and pitch angle that magnetosonic waves can effectively scatter vary depending on the locations and geomagnetic activity. Our model agrees with the statistically observed wave distribution and ambient plasma environment with a coefficient of determination of > 0.9. The model is valid in all MLTs, 2 ≤ L^* < 6, |λ| < 20°, and Kp ≤ 6.

• Structural Engineering and Mechanics
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• v.53 no.2
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• pp.277-296
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• 2015

The objective of this paper is to investigate the surface waves in fibre-reinforced anisotropic thermoelastic medium subjected to gravity field. The theory of generalized surface waves has firstly developed and then it has been employed to investigate particular cases of waves, viz., Stoneley waves, Rayleigh waves and Love waves. The analytical expressions for displacement components, force stress and temperature distribution are obtained in the physical domain by using the harmonic vibrations. The wave velocity equations have been obtained in different cases. The numerical results are given and presented graphically in Green-Lindsay and Lord-Shulman theory of thermoelasticity. Comparison was made with the results obtained in the presence and absence of gravity, anisotropy, relaxation times and parameters for fibrereinforced of the material medium. The results indicate that the effect of gravity, anisotropy, relaxation times and parameters for fibre-reinforced of the material medium are very pronounced.