• Journal of Nutrition and Health
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• 제36권9호
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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.

• 한국조경학회지
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• 제31권4호
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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.

• 전기학회논문지P
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• 제62권2호
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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.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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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.

• 디지털융복합연구
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• 제12권1호
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• pp.467-473
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• 2014

본 연구의 목적은 점진적 이완기법을 대학 양궁선수들에게 적용한 후 뇌파측정과 혈압, 심박수 등의 생리적인 변인의 측정을 통하여, 호흡을 통한 점진적 이완의 효과성을 검증하고 궁극적으로 양궁의 경기수행력을 향상시키는데 목적이 있다. 본 연구의 대상자들은 여자 양궁선수 13명을 대상자로 선정하였고, 12주간 Jacobson의 점진적 이완기법을 적용하여 1주일에 3일, 1회 약 15~20분 동안 훈련 후, 동일 대상자 13명의 뇌파와 혈압, 심박수를 측정하였다. 본 연구의 자료처리는 SPSS18.0프로그램을 이용하여 실험 대상자의 일반적인 특정을 알아보기 위하여 기술분석을 실시하였고 단일 집단의 뇌파, 혈압, 심박수의 사전 사후의 변화를 알아보기 위하여 대응 t-test(paired t-test)를 실시하였다. 모든 통계적 유의 수준은 ${\alpha}=0.5$로 하였고, 다음과 같은 결과를 얻었다. 첫째, 12주간 처치 후 상대 ${\alpha}$파, 상대 ${\beta}$ 중에서 상대${\alpha}$파가 통계적으로 유의한 수준으로 증가하였고, 상대 ${\beta}$파의 변화는 나타내지 않았다. 둘째, 12주간 처치 후 혈압의 변화로는 수축기압의 변화는 나타내지 않았고, 이완기 혈압의 변화가 통계적으로 유의한 수준으로 나타났다. 셋째, 심박수의 변화는 통계적으로 유의하게 나타나지 않았다. 이상의 결과를 종합하여 볼 때 호흡을 통한 점진적 이완기법은 대학 양궁선수들에게 긍정적인 영향을 미치는 것으로 나타났다.

• 대한기계학회논문집B
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• 제38권12호
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• pp.1009-1015
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• 2014

본 연구는 NACA0012 천음속 에어포일 유동에 있어서 비평형 응축이 Force 계수(압력, 양력 및 항력계수)에 미치는 영향을 TVD 수치해석을 통하여 연구하였다. 정체점 온도 298 K, 받음각 ${\alpha}=3^{\circ}$인 경우, 주류 마하수 0.78~0.81에서는 정체점 상대습도의 증가함에 따라 양력은 단순 감소한다. 반면 Lift force break 마하수 영역의 주류 마하수에서는 정체점 상대습도의 증가에 따라 양력은 오히려 증가한다. 받음 각 ${\alpha}=3^{\circ}$, 정체점 상대습도가 0%인 경우, 주류 마하수의 증가에 따라 항력은 급격하게 증가하지만, 응축의 영향이 큰 60%인 경우에는 주류 마하수의 증가에 조금 증가할 뿐이다. 동일한 주류 마하수인 경우 비평형 응축에 따른 전 항력의 감소는 받음각과 정체점 상대습도가 증가할수록 크게 된다. 응축이 없는 ${\Phi}_0=0%$인 경우는 주류 마하수가 크고 받음각이 클수록 Wave drag은 크게 되나 응축의 영향이 비교적 큰 ${\Phi}_0=50%$ 이상인 경우는 오히려 Wave drag이 작아지는 것으로 나타났다. 한편, 정체점 상대습도가 낮고, 주류 마하수가 클수록 충격파 직전의 최대 마하수는 커지는 것으로 나타났다.

• 대한인간공학회지
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• 제17권1호
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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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• 제1권4호
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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.