• Journal of Nutrition and Health
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• v.36 no.9
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• pp.918-923
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• 2003

L-theanine Is an amino acid in green tea and has been known to decrease serotonin and increase norepinephrine in rat brains, and also reported to produce mental relaxation, lower blood pressure and improve learning ability in human beings. But, few studies on these effects for human beings have been conducted so far. This study was conducted to evaluate the effect of L-theanine on the release of brain alpha waves known to be related with mental relaxation and concentration. Twenty healthy male volunteers aged 18 to 30 years without any Physical and Psychological diseases were recruited through written advertisement. Alpha power values of EEG as a surrogate marker of mental relaxation and concentration were measured in frontal and occipital regions for 40 minutes after administration of four placebo or test tablets and 20 minute resting period. The same procedure crossed over at 7-day intervals. We analyzed average alpha power values in frontal and occipital regions at 10 minute intervals. Repeated ANOVA revealed that there were significant differences of occipital alpha power values between placebo and test groups with high anxiety (p < 0.05). The mean values at 20,30,40,50 and 60 minute intervals were 0.23, 024, 0.28, 0.25 and 0.34 in placebo, respectively and 0.23, 0.29, 0.40, 0.34, and 0.45 in test, respectively. But there were no significant differences of frontal and occipital alpha power values between placebo and test groups with low anxiety (p > 0.05) . The results of this study suggest that L-theanine containing tablets promote the release of alpha waves related to mental relaxation and concentration in young adult males.

• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.4
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• pp.49-56
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• 2003

This study is to find physiological effects of acoustic information on landscape preference. Both the volume and the rate of $\alpha$-waves and $\beta$-waves were used to measure the effects in the study. The result of this study are summarized as follows: The outputting amount of $\alpha$-waves are sorted by different types of visual and acoustic factors. The results show that acoustic factors interacted with visual factors. That is, although visual factors are positive, the volume of $\alpha$-waves depends upon the character of acoustic factors; positive acoustic factors produce more $\alpha$-waves than negative or neutral(soundless) acoustic factors. Also the volume of $\alpha$-waves increase in the case of positive acoustic factors even if there is the same negative visual information. The results show that the volume of $\alpha$-waves increase without connecting with the types of visual factors. The volume of $\beta$-waves are largely reduced when visual stimulus is positive and soundless stimulus is provided. On the other hand, they generally increase when both visual and acoustic stimuli are negative, which fosters extremely unstable, tense and upset stress. The rate of $\alpha$-waves increase according to supplying positive acoustic factors in the opposed visual factors. The rate of wave(shouldn't be $\alpha$-waves\ulcorner) is high if both visual and acoustic factors are positive, so it is the most comfortable and causes no stress. Preference is the lowest if visual and acoustic factors are negative, but a -waves are conspicuously low in positive visual and negative acoustic factors.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.2
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• pp.103-109
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• 2013

In this study, the three sounds effects on subjects due to EEG type, and it researched to find optimal sound to increase their amenity and productivity. EEG and HRV were compared and analyzed in the environmental test room by classifying subjects into two type: A and B. The condition of the environmental test room was in temperature $31[^{\circ}C]$, relative humidity 50[RH%], air current speed 0.02[m/s] and illuminance 1000[lux] with setting up three different sounds which are U type sound, V type sound and Z type sound. The result of this study, at U type sound for A and B type, relative $M{\alpha}$ wave, relative $M{\beta}$ wave and SEF50 were revitalized. Also at Z type sound for A and B type, stress index, fatigue degree and HRT were decreased and SDNN was revitalized. Therefore U type sound is very effective to increase amenity, productivity and concentration, and Z type sound is very effective to decrease stress and fatigue degree.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.479-482
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• 2001

This paper proposes a modified $\alpha$ conduction mode for controlling the output voltage magnitude of three-phase square-wave VSIs with an R-L load. From the viewpoint of both power capacity and switching losses, three-phase square-wave inverters are now used in most high power systems. When the square-wave VSI is driven with $\alpha$ conduction mode to control the magnitude of output voltages, interval over than half period is operated with $180^{\circ}$ conduction mode and the other interval with $120^{\circ}$ conduction mode. In $120^{\circ}$ conduction mode operation, two output terminals are connected to DC supply and the third one remains open. The potential of this open terminal will depend on the load characteristics and is unpredictable except the case of pure resistive loads. To cope this problem, we propose the modified α conduction mode.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.316-318
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• 2004

In this study, the influence of electromagnetic wave effected on human body of light sensing was classified. Subjects of the eye was stimulated by the rays of LED and the measured electrical signals(EEG, EOG and ERG) in human body were compared and analyzed in the case of exposed at electromagnetic wave or not. The result show that when the subjects were not exposed at electromagnetic wave, the ratio of a wave has a large percentage in the EEG signal and the ratio of $\beta$ wave has come to good.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2724-2726
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• 2002

The effect which electromagnetic wave has influence on visual activity of human, was investigated in this study. The EEG and the EOG generated by the rays of LED were measured in shield room when the subject were exposed at electromagnetic wave(820MHz, 2mV) or not exposed. Each component of the EEG was compared and evaluated on being exposed at electromagnetic wave or not. As a result was $\alpha$ wave was represented relatively low level in the case of exposed at electromagnetic wave and $\beta$ wave was represented relatively low level in the case of not exposed.

• Journal of Digital Convergence
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• v.12 no.1
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• pp.467-473
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• 2014

The purpose of this study is to monitor the physiological changes by measuring EEG, blood pressure, heart rate, etc after applying progressive relaxation technique to university archery players in order to verify the effect of progressive relaxation through respiration, and, ultimately, improve an athlete's archery performance. This study chose 13 female archery athletes. The EEG, blood pressure, and heart rate of the athletes were measured before applying Jacobson's progressive relaxation technique for 12 weeks, during which the EEG, blood pressure, and heart rate were measured 3 times a week after 15 to 20 minutes of training before every measurement. We used the SPSS18.0 program for technical analysis to check the general features of the athletes and carried out the paired t-test to examine the changes made to the EEG, blood pressure, and heart rate of a single test group before and after the experiment. All statistical level of significance was maintained at ${\alpha}=0.5$. The results are as follows. First, after 12 weeks of appliance, between the targets' relative ${\alpha}$ wave and ${\beta}$ wave, the relative ${\alpha}$ wave showed a statistically significant increase while the relative ${\beta}$ wave showed no changes. Second, after 12 weeks of appliance, in terms of blood pressure, the systolic pressure showed no changes while the diastolic pressure showed a statistically significant change. Third, there was no statistically significant change to the heart rate. In conclusion, progressive relaxation through breathing has a positive effect on the archery athletes.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.12
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• pp.1009-1015
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• 2014

The present study investigated the effects of non-equilibrium condensation with the angle of attack on the coefficients of pressure, lift, and drag in the transonic 2-D flow of NACA0012 by numerical analysis of the total variation diminishing (TVD) scheme. At $T_0=298k$ and ${\alpha}=3^{\circ}$, the lift coefficients for $M_{\infty}=0.78$ and 0.81 decreased monotonically with increasing ${\Phi}_0$. In contrast, for $M_{\infty}$ corresponding to the Mach number of the force break, $C_L$ increased with ${\Phi}_0$. For ${\alpha}=3^{\circ}$ and ${\Phi}_0=0%$, $C_D$ increased markedly as $M_{\infty}$ increased. However, at ${\Phi}_0=60%$ and ${\alpha}=3^{\circ}$, which corresponded to the case of the condensation having a large influence, $C_D$ increased slightly as $M_{\infty}$ increased. The decrease in profile drag by non-equilibrium condensation grew as the angle of attack and stagnation relative humidity increased for the same free stream transonic Mach number. At ${\Phi}_0=0%$, the coefficient of the wave drag increased with the attack angle and free stream Mach number. When ${\Phi}_0$ > 50%, the coefficient of the wave drag decreased as ${\alpha}$ and $M_{\infty}$ increased. Lowering ${\Phi}_0$ and increasing $M_{\infty}$ increased the maximum Mach number.

• Journal of the Ergonomics Society of Korea
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• v.17 no.1
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• pp.1-9
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• 1998

The sensitivity of the emotion evoked visually by IAPS was attempted to be defined using EEG(electroencephalogram). Twenty university students were participated in this study. Their EEG was measured and analyzed in terms of frequency range such as delta, theta, alpha and beta wave. The results showed that alpha increased, but delta and beta decreased with positive emotional progress. Inter-variation between alpha and delta in F4 and beta variation in P3 were indicative of the evaluation sensitivity of human emotion.

• Water Engineering Research
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• v.1 no.4
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• pp.293-298
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• 2000

Optimal values of $\alpha$ characterizing the linear dispersion property in the modified Boussinesq equations are determined by minimizing the combined relative errors of the phase and group velocities. The value of $\alpha$ is fixed in previous studies, whereas it is varying in the present study. The phase and group velocities are calculated by using variable $\alpha$ and compared to those of the linear Stokes wave theory and previous studies. It is found that the present study produces the best match to the linear Stokes theory.