• Biomedical Science Letters
• /
• v.18 no.4
• /
• pp.428-434
• /
• 2012

Epilepsy is a chronic neurological disease showing a symptom of repeated seizures without any other physical disorders. Among the diagnostic examination for epilepsy, the electroencephalogram (EEG) has been known as an important test. This study aimed to investigate the EEG with photic stimulation in the pediatric epilepsy patients. They underwent digital sleep and waking EEGs or waking EEGs with photic stimulation. Epilepsy type, seizure history, and season of occurring seizure were analyzed. Epilepsy patients showed more response during the period of photic-on and eye close at the frequency of 10~20 Hz during the EEG activation procedure. Photoparoxysmal response (PPR) was shown in 206 patients out of total 1,551 epilepsy patients. PPR was appeared more frequently during summer and winter seasons, and especially in the patients who had a history of seizure. During the PPR, EEG pattern showed spike (77.18%), theta (9.71%), and spike + theta (13.11%). On the other hand, beta and theta waves were not significantly changed by photic stimulation. However, alpha wave was decreased and delta wave was increased by photic stimulation (P<0.05). These changes may be due to temporarily altered electrophysiological function of the epileptic patient's brain by the photic stimulation. There was no difference in the EEG pattern between the left and right side in the brain. In conclusion, condition of photic-on with closed eyes and frequency of 10~20 Hz during the procedure of EEG activation could be appropriate for obtaining a definite photoparoxysmal response in the electroencephalogram of the pediatric epilepsy patients.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.11
• /
• pp.1914-1922
• /
• 2008

In this paper, examined characteristics of EEG(electroencephalogram) variation when the stimulation was given to lung-wan(CV12), Shin-gwol(CV8) and Gwan-won(CV4) which were some of the acupuncture point, through indirect moxibustion and No stimulation. The EEG signals were measured before the stimulation, during the stimulation, and 1 hour after the stimulation. The measured time domain data were converted to the frequency domain data FFT(Fast Fourier Transform) and frequency power spectrum. Then the $\alpha,\beta,\delta$, and $\theta$ waves were analyzed for variation to the amplitude of vibration according to the stages of stimulation.

• Archives of Pharmacal Research
• /
• v.27 no.1
• /
• pp.31-34
• /
• 2004

The electrochemical behavior of doxorubicin hydrochloride was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV). From CV and SWV studies of doxorubicin hydrochloride in the acetate buffers of various pH values, it was found that protons were involved in the reduction of the antibiotic at the $H^+/e^$- ratio at one ( $\DeltaEp/pH =-53 ∼ -61 mV at 23^{\circ}C$), proposing the electrochemical reduction of the quinone moiety in its anthraquinone aglycone. Its electrochemical behavior was pseudo-reversible in the acetate buffer of pH 3.5 by exhibiting the well-defined single cathodic and anodic waves and the ratio of $lp^a/lp^c$ at approximately one over the scan rates of 10∼100 mV/s. Fast and sensitive SWV showing a single peak of doxorubicin has been applied for its quantitative analysis using an acetate buffer of pH 3.5. A linearity was obtained when the peak currents (lp) were plotted against concentrations of doxorubicin in the range of $5.0\times10^{-7} M∼1.0\times10^{-5}$M with a detection limit of $1.0\times10^{-7}$ M.

• Journal of Wetlands Research
• /
• v.14 no.4
• /
• pp.439-455
• /
• 2012

Coupled wave induced current modeling system(WIC) was developed from combining with the nearshore spectral wave model, SWAN, the wave induced force model, WIF, and the flow model, EFDC. The reasonable results were obtained from WIC modeling system. The ratio of the wave height calculated with respect to refraction and diffraction effects over submerged spherical shoal was occurred approximately 1~5 % errors compared to Goda(2000)'s result. The radiation stress suggested by Longuet-Higgins and Stewart(1960), the stresses due to rollers in breaking waves proposed by Dally and Osiecki(1994), and Kim(2004)'s new spreading approach instead of the previous lateral mixing approach were added to calculate wave induced force. The results of the WIC modeling system show good agreement with Nishimura et al.(1985)'s laboratory measurements and better than Kim(2004)'s 2 dimensional depth averaged numerical computations for a plane beach with detached breakwater. The present flow field computed agrees reasonably well with the measured flow field. The relative merit of WIF model in WIC modeling system is unconditional stable for time increment.

• Journal of Biomedical Engineering Research
• /
• v.19 no.1
• /
• pp.81-90
• /
• 1998

Electromagnetic waves may induce various effects on nervous tissues either by thermal or non-thermal mechanisms. This paper intoduces a method to evalute the non-thermal effect to central nervous system by measuring the EEGs of the rabbits treated by nimodipine before exposed to weak microwave field. 20 rabbits were divided into 2 groups and their EEGs were measured after their head section were exposed to 2,450 MHz microwave with the power density of 10 dBm and 20 dBm respectively for 10 minutes and compared with those of the 3rd group of 10 rabbits which were not exposed. The 4th group of 10 rabbits were intravenously given with nimodipine before exposed to 20 dBm field to determine whether this drug would reverse the EEGs changes induced by weak microwave irradiation. As field poser exceeded 20 dBm although no significant physiological changes were observed, total induced EEGs power was remarkably decreased suggesting the presence of CNS activation. Using Fourier analysis on the EEGs signal it was found that remarkable decrease in delta band and increase in the alpha and beta bands in a significant manner(P<0.05) compared to control group. The changes were, however, not reversed by nimodipine-treatment. The effects may be pure thermal in nature because no significant change has been observed in nimodipine treated rabbits.

• Science of Emotion and Sensibility
• /
• v.22 no.3
• /
• pp.3-20
• /
• 2019

With advancements in technology of virtual reality, it is used for various purposes in many fields such as medical care and healthcare, but as the same time there are also increasing reports of nausea, eye fatigue, dizziness, and headache from users. These symptoms of motion sickness are referred to as cybersickness, and various researches are under way to solve the cybersickness problem because it can cause inconvenience to the user and cause adverse effects such as discomfort or stress. However, there is no official standard for the causes and solutions of cybersickness at present. This is also related to the absence of tools to quantitatively measure the cybersickness. In order to overcome these limitations, this study proposed quantitative and objective cybersickness evaluation method. We measured 128-channel EEG waves from ten participants experiencing visually stimulated virtual reality. We calculated the relative power of delta and alpha in 11 regions (left, middle, right frontal, parietal, occipital and left, right temporal lobe). Multiple regression models were obtained in a stepwise manner with the motion sickness susceptibility questionnaire (MSSQ) scores indicating the susceptibility of the subject to the motion sickness. A multiple regression model with the highest under the area ROC curve (AUC) was derived. In the multiple regression model derived from this study, it was possible to distinguish cybersickness by accuracy of 95.1% with 11 explanatory variables (P_D.MF, P_D.LP, P_D.MP, P_D.RP, P_D.MO, P_A.LF, P_A.MF, P_A.RF, P_A.LP, P_A.RP, P_A.MO). In summary, in this study, objective response to cybersickness was confirmed through 128 channels of EEG. The analysis results showed that there was a clearly distinguished reaction at a specific part of the brain. Using the results and analytical methods of this study, it is expected that it will be useful for the future studies related to the cybersickness.

• Journal of Korean Ophthalmic Optics Society
• /
• v.5 no.1
• /
• pp.101-105
• /
• 2000

This study was to investigate the effect of EEG wave type on visual cortex of visual target according to position of fixation point on the Korean. Visual evoked potential system used the BIO-Pag and recorded to 586 computer. The illumination was 500 lux and the visual target was red light dot of 3 cm size. The results of the convergence and divergence as follows: The visual stimulation waves on the visual cortex have about 70% of delta wave, about 10% of beta wave, about 9% of theta wave and about 7% of alpha wave respectively. The convergence state was much more appeared the fast wave on the comparative of the divergence. Therefore, the convergence state was much more producted the beta and alpha wave on the comparative of the divergence. On the other hand, on the convergence and divergence, the histogram amplitude of EEG wave appeared almost the non-Gaussian shape. According to the phase analysis of amplitude of EEG wave almost all type was linear shape.

• The Bulletin of The Korean Astronomical Society
• /
• v.36 no.2
• /
• pp.141.1-141.1
• /
• 2011

New CCD BVR light curves of BD And are presented. Our light curves with nearly equal depths for both primary and secondary eclipses show well-defined photometric waves outside eclipse for all of BVR bandpasses. The orbital period is greatly revised as $0.^d92580519$ which is twice longer than that known previously. Sixteen timings from our observations and thirteen ones from the SuperWASP measurements were calculated. All available timings over 76 years, including ours, were analyzed to figure out the dynamical behavior of the system. It was found that the recent CCD O-C residuals varied in a cyclical way with a period of $9.^y18$ and a semi-amplitude of $0.^d0046$. The secondary period of $9.^y18$ is the most shortest one among those which have been ever found in the short period RS CVn binary stars. The periodic variation most likely arises from the light-travel time effect due to a low-mass ($m_3{\sim}0.88\;M_{\odot}$) tertiary companion moving in an orbit with an large eccentricity ($e_3$=0.70) and a low inclination ($i_3{\sim}28^{\circ}$). The Applegate mechanism could not operate properly in both components because the model parameters require too much large luminosity changes of ${\Delta}L/L_{p,s}$ > 10. The new light curves were synthesized using the 2003 version of Wilson-Divinney code. It was found useful to model two huge spots on the surface of the hotter star and a third-light in order to minimize the residuals from the observations. Astronomical basic parameters were deduced from our photometric solution.

• Sleep Medicine and Psychophysiology
• /
• v.17 no.2
• /
• pp.75-84
• /
• 2010

The cyclic alternating pattern (CAP) is a periodic EEG activity in NREM sleep, characterized by sequences of transient electrocortical events that are distinct from background EEG activities. A CAP cycle consists of two periodic EEG features, phase A and subsequent phase B whose durations are 2-60 s. At least two consecutive CAP cycles are required to define a CAP sequence. The CAP phase A is a phasic EEG event, such as delta bursts, vertex sharp transients, K-complex sequences, polyphasic bursts, K-alpha, intermittent alpha, and arousals. Phase B is repetitive periods of background EEG activity. The absence of CAP more than 60 seconds or an isolated phase A is classified as non-CAP. Phase A activities can be classified into three subtypes (A1, A2, and A3), based on the amounts of high-voltage slow waves (EEG synchrony) and low-amplitude fast rhythms (EEG desynchrony). CAP rate, the percentage of CAP durations in NREM sleep is considered to be a physiologic marker of the NREM sleep instability. In insomnia, the frequent discrepancy between self-reports and polysomnographic findings could be attributed to subtle abnormalities in the sleep tracing, which are overlooked by the conventional scoring methods. The conventional scoring scheme has superiority in analysis of macrostructure of sleep but shows limited power in finding arousals and transient EEG events that are major component of microstructure of sleep. But, it has recently been found that a significant correlation exists between CAP rate and the subjective estimates of the sleep quality in insomniacs and sleep-improving treatments often reduce the amount of CAP. Thus, the extension of conventional sleep measures with the new CAP variables, which appear to be the more sensitive to sleep disturbance, may improve our knowledge on the diagnosis and management of insomnia.

• Journal of Korean Academy of Nursing
• /
• v.53 no.4
• /
• pp.453-467
• /
• 2023

Purpose: This study investigated the cumulative effects of depressive symptoms on cognitive function over time in community-dwelling older adults. Methods: Data were investigated from 2,533 community-dwelling older adults who participated in the Korean Longitudinal Study of Aging (KLoSA) from the 5th (2014) to the 8th wave (2020). The association between cumulative depressive symptoms and cognitive function was identified through multiple regression analysis. Results: When the multiple regression analysis was conducted from each wave, the current depressive symptoms scores and cognitive function scores were negatively associated, regardless of the waves (B5th = - 0.26, B6th = - 0.26, B7th = - 0.26, and B8th = - 0.27; all p < .001). Further, when all the previous depressive symptoms scores were added as explanatory variables in the 8th wave, the current one (B8th = - 0.09, p < .001) and the previous ones (B5th = - 0.11, B6th = - 0.09, and B7th = - 0.13; all p < .001) were also negatively associated with the cognitive function score. The delta R², which indicates the difference between the model's R² with and without the depressive symptoms scores, was greater in the model with all the previous and current depressive symptoms scores (6.4%) than in the model with only the current depressive symptoms score (3.6%). Conclusion: Depressive symptoms in older adults have a long-term impact. This results in an accumulated adverse effect on the cognitive function. Therefore, to prevent cognitive decline in older adults, we suggest detecting their depressive symptoms early and providing continuous intervention to reduce exposure to long-term depressive symptoms.