• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.556-559
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• 1999

In order to investigate the influence on dielectric characteristic due to physical structural change of specimens, we investigated the frequency and temperature dependency of tan $\delta$ for virgin specimen and mixtured specimens in the temperature range of 25[$^{\circ}C$] ~ 120[$^{\circ}C$], frequency range of 300(mv) ~ 1500[mV] An experimenatal specimen is selected as Low Liner Density Polyethylene (LLDPE) and Ethylene Vinyl Acetate(EVA) (thickness 200[$\mu$m]) produced by mixture ratio of 50:50, 60:40, 70:30 and 80:20. From the results of XRD it can be confirmed that the peak of LLDPE and EVA made by mixture ratio of 70:30 at 2$\theta$= 21.4$^{\circ}$is higher and the peak made by amorphous contribution at 2$\theta$= 19.5[$^{\circ}$] is almostly constant without no concern.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.342-347
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• 2011

Nanocrystalline TiN films were deposited on Si(100) substrate using asymmetric pulsed DC reactive magnetron sputtering. We investigated the growing behavior and the structural properties of TiN films with change of duty cycle and pulsed frequency. Grain size of TiN films were decreased from 87.2 nm to 9.8 nm with decrease of duty cycle. The $2{\theta}$ values for (111) and (200) crystallographic planes of the TiN films were also decreased with decrease of duty cycle. This shift in $2{\theta}$ could be attributed to compressive stress in the TiN coatings. Thus, the change of plasma parameter has a strong influence not only on the microstructure but also on the residual stresses of TiN films.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.224-227
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• 2006

We have chained 459nm blue laser radiation generated by intracavity sum frequency generation( SFG ) due to the mixing of the 1064 nm laser output of a Nd:YVO4 pumped by diode and the 809nm radiation from higg-power semiconductor laser(500mW). The maximum blue output power of 0.95 mW was obtained using 400 mW input power of semiconductor laser at the type II phase matching condition (${\psi}=90^{\circ}\;{\theta}=90^{\circ}$). The threshold input power of blue laser generation was 120 mW.

• Korean Journal of Acupuncture
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• v.27 no.2
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• pp.141-157
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• 2010

Objectives : The aim of this study is to examine the effects of acupuncture at PC7(Daereung) on normal human EEG using power spectral analysis. Methods : EEG power spectrum exhibits site-specific and state-related differences in specific frequency bands. In this study, power spectrum was used as a measure of complexity. 30 subjects (16 males and 14 females; averaged age = 23.4 years) were engaged with thirty channel EEG study. Results : In $\alpha$(alpha) band, the power values at Fp1, Fp2, F7, F8 channels(p<0.05) during PC7 treatment were significantly decreased. But, the power values at Fz channel(p<0.05) during non-acupoint treatment was significantly decreased. In $\beta$(beta) band, the power values at Fp1, Fp2 channels(p<0.05) during PC7 treatment were significantly decreased. But, the power values at Fz channel(p<0.05) during non-acupoint treatment was significantly decreased and at F8, TCP2 channels(p<0.05) during non-acupoint treatment were increased. In $\theta$(theta) band, the power values at Fp1, Fp2, F7, F8 channels(p<0.05) during PC7 treatment were significantly decreased. But, the power values at Fz channel(p<0.05) during non-acupoint treatment was significantly decreased. In $\delta$(delta) band, the power values at Fp1, Fp2, F7, Fz, F8 channels (p<0.05) during PC7 treatment were significantly decreased. But, the power values at Fz channel (p<0.05) during non-acupoint treatment was significantly decreased. $\alpha/\beta$ values during PC7 treatment were decreased. $\beta/\theta$ values during PC7 treatment were decreased. Conclusion : These results suggest that acupuncture at PC7 induce the change on $\alpha$(alpha), $\beta$(beta), $\theta$ (theta), $\delta$(delta) wave values being decreased and and bothe $\alpha/\beta$ and $\beta/\theta$ values being decreased respectively. This is considered that acupuncture at PC7 affects the activity of cerebral cortex and endocrine system.

• Science of Emotion and Sensibility
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• v.14 no.2
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• pp.269-278
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• 2011

This paper illustrates the inter-relationship between the theta/alpha ratio of the EEG signal and multiple HRV related parameters associated with the cardiovascular system response during event-related stimuli. Both EEG and PPG signals were simultaneously recorded in 21 healthy subjects. All subjects had their attention focused on the CNT program for nine minutes. Time-frequency analysis was applied to the EEG and PPG signals. The theta/alpha ratio was extracted from the EEG results, and the HRV features, including beat interval(1), SDNN(2), RMSSD(3), NN50(4), LF(5), HF(6), and LFIHF(7), were extracted from the PPG. Through multiple linear regression, the relationship ($R^2$) between the multiple combined features and the theta/alpha rhythm was identified. As a result, the combinations of $R^2$($R^2=0.253$; seven dimensions) and the theta/alpha ratio indicated a higher inter-relationship value than those of other combinations. The combinations of features that were greater than three dimensions, based on {SDNN(2), HF(6)}, generally showed higher $R^2$ value. We demonstrate that the high dimensional combinations had a higher correlation than did the low dimensional combinations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.4 s.247
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• pp.298-305
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• 2006

The flow around a circular cylinder which oscillates rotationally with a relatively high forcing frequency has been investigated experimentally using flow visualization and hot-wire measurements. Dominant parameters are Reynolds number (Re), oscillation amplitude $({\theta}_A)$, and frequency ratio $F_R=f_f/f_n$, where $f_f$ is the forcing frequency and $f_n$ is the natural frequency of vortex shedding. Experiments were carried out under the conditions of $Re=4.14{\times}10^3,\;{\theta}_A={\pi}/6$, and $0{\leq}F_R{\leq}2$. The effect of frequency ratio $F_R$ on the flow structure of wake was evaluated by measuring wake velocity profile and spectral analysis of hot-wire signal. Depending on the frequency ratio $F_R$, the cylinder wake has 5 different flow regimes. The vortex formation length and vortex shedding frequency are changed significantly before and after the lock-on regime. The drag coefficient was reduced under the condition of $F_R<1.0$ and the maximum drag reduction is about 33% at $F_R=0.8$. However, the drag is increased as $F_R$ increases beyond $F_R=1.0$. This active flow control method can be effective in aerodynamic applications, if the forcing parameters are selected optimally.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.04a
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• pp.15-25
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• 2000

Cardiac, respiratory, electrodermal and frontal (F3, F4) EEG responses were analyzed and compared during to slides of International Affective Picture System (IAPS) in the study on 42 students. Physiological responses during 20s of exposure to slides intended to elicit happiness (nurturant and erotic), sadness, disgust, surprise, fear or anger emotions were quite similar and were expressed in heart rate (HR) deceleration, decreased HR variability (HRV), specific SCR, increased non-specific SCR frequency (N-SCR), and EEG changes exhibited in theta increase, alpha-blocking and increased beta activity, and frontal asymmetry. However, some emotions demonstrated variations of the response magnitudes, enabling to differentiate some paris of emotions by several physiological parameters. The profiles showed higher magnitudes of HRV and EEG responses in exciting (i.e., erotic) and higher cardiac and respiratory responses in surprise. The most different pairs were exciting-surprise (by HR, HRV, theta, and alpha asymmetry), exciting-sadness (by theta, alpha, and alpha asymmetry), and exciting-fear (by HRV, theta, F3 alpha, and alpha asymmetry). Nurturant happiness yielded the least differentiation. Differences were found as well within negative emotions, e.g., anger-sadness were differentiated by HRV and theta asymmetry, while disgust-fear by N-SCR and beta asymmetry. Obtained results suggest that magnitudes of profiles of physiological variables differentiate emotions evoked by affective pictures, despite that the patterns of most responses were featured by qualitative similarity in given passive viewing context.

• Journal of the Korean Electrochemical Society
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• v.3 no.2
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• pp.109-114
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• 2000

The relation between the phase-shift profile fur the intermediate frequencies and the Langmuir adsorption isotherm at the poly-Ir/0.1 M $H_2SO_4$ aqueous electrolyte interface has been studied using ac impedance measurements, i.e., the phase-shift methods. The simplified interfacial equivalent circuit consists of the serial connection of the electrolyte resistance $(R_s)$, the faradaic resistance $(R_F)$, and the equivalent circuit element $(C_P)$ of the adsorption pseudoca-pacitance $(C_\phi)$. The comparison of the change rates of the $\Delta(-\phi)/{\Delta}E\;and\;\Delta{\theta}/{\Delta}E$ are represented. The delayed phase shift $(\phi)$ depends on both the cathode potential (E) and frequency (f), and is given by $\phi=tan^{-1}[1/2{\pi}f(R_s+R_F)C_P]$. The phase-shift profile $(-\phi\;vs.\;E)$ for the intermediate frequency (ca. 1 Hz) can be used as an experimental method to determine the Langmuir adsorption isotherm $(\theta\;vs.\;E)$. The equilibrium constant (K) for H adsorption and the standard free energy $({\Delta}G_{ads})$ of H adsorption at the poly-Ir/0.1 M $H_2SO_4$ electrolyte interface are $2.0\times10^{-4}$ and 21.1kJ/mol, respectively. The H adsorption is attributed to the over-potentially deposited hydrogen (OPD H).

• Korean Journal of Biological Psychiatry
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• v.20 no.4
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• pp.166-178
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• 2013

Objectives Alteration of epigenetic effects of testosterone during early development was suggested as an ancillary mechanism for the genesis of schizophrenia. EEG coherence was thought to be a marker for cerebral laterality of which important determinant was testosterone during early development. We studied sex-related differences of EEG coherences between patients with schizophrenia and controls to examine the sex effects in the genesis of schizophrenia. Methods EEG was recorded in 35 patients with schizophrenia and 46 healthy controls in the eyes closed resting state. Pair-wise EEG coherences were calculated over delta, theta, alpha, beta and gamma frequency bands. To examine the differences of EEG coherence according to sex in each group, ANCOVA was performed using Statistical Analysis system (SAS, Ver 9.3) and R (Ver 2.15.2). Results Healthy control males showed more increased right intrahemispheric coherences than healthy control females in delta, theta, alpha and beta frequency bands. In patients with schizophrenia, this male dominant pattern in right intrahemispheric coherences was attenuated especially in alpha and beta bands. Healthy control females showed more increased interhemispheric coherences than healthy control males in delta, theta, beta and gamma frequency bands. In patients with schizophrenia, these female dominant patterns in interhemispheric coherences were attenuated especially in delta, theta, and beta bands, which were commonly observed in frontal to central areas. Conclusion Sex differences in resting EEG coherences were attenuated in schizophrenia patients. These results imply that sex-related aberrant cerebral lateralization might exist in patients with schizophrenia, which are partly due to sex hormones via epigenetic mechanisms.

• Sleep Medicine and Psychophysiology
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• v.2 no.2
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• pp.133-137
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• 1995

The author reviews current knowledge about what REM sleep is and where and how it is generated. REM sleep is the state in which our most vivid dreams occur. REM sleep is identified by the simultaneous presence of a desynchronized cortical EEG, an absence of activity in the antigravity muscles(atonia), and periodic bursts of rapid eye movements. Another characteristic phenomena of REM sleep are the highly synchronized hippocampal EEG of theta frequency and the ponto-geniculo-occipital(PGO) spike. All these phenomena can be explained in terms of changes in neuronal activity. Transection studies have determined that the pons is sufficient for generating REM sleep. Lesion studies have identified a small region in the lateral pontine tegmentum corresponding to lateral portions of the nucleus reticularis pontis oralis(RPO) and the region immediately ventral to the locus coeruleus, which is required for REM sleep. Unit recording studies have found a population of cells within this region that is selectively active in REM sleep. Cholinergic neurons of the giant cell field of pontine tegmentum(ETG), which is 'REM a sleep-on cells', has shown to be critically involved in the generation of REM sleep. Noradrenergic neurons of the locus coeruleus and serotonergic neurons of the dorsal raphe, which are called 'REM sleep-off cells', appear to act in a reciprocal manner to the cholinergic neurons. It is proposed that the periodic cessations of discharge of 'REM sleep-off cells' during REM sleep might be significant for the prevention of the desensitization of receptors of these neurons.