• Proceedings of the ESK Conference
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• 1997.04a
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• pp.3-9
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• 1997

EEG(electroencephalogram) is attempted to determination of human emotion. Ten university students were participated in this study. Ten auditory stimuli were presented for a subject to evoke emotion. Data homogeneity according to brain local area and basic mechanism of relative variation for combinational delta, theta, alpha and beta waves were analyzed. As the result, the local area characterized by factor analysis and the relative variation of alpha-delta wave can be considered as the determinants of human emotion.

• Journal of Ocean Engineering and Technology
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• v.21 no.2 s.75
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• pp.22-34
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• 2007

We present basic data for developing new research topics and closely examine the existing data on the development and organization of the Nakdong River Estuary Delta by analyzing various studies of the area, including ocean engineering, coastal engineering, ocean environmental engineering, geomorphological, and geological studies. We first defined the general concepts related to the estuary and delta and reviewed the historical development of the Nakdong River Estuary Delta over the past 100 years. We then examined the origin and core elements of the estuary deposits that constitute the delta. In addition, we scrutinized the main factors affecting the development of the delta and analyzed existing research on delta development mechanisms by core researchers. The construction of an estuary barrage is one of the main factors effecting estuarine circulation and has altered the physical oceanic environment, area of deposition, atmospheric environment, and vegetation community of the delta. These factors affect the estuary circulation in turn, altering the delta. Along the Nakdong River, an unsteady-state sandy barrier appears at approximately three times the distance of the wavelength of incident offshore waves, and this terrain forms approximately 10-15 years after reclamation in the interdistributary upper stream and transforms the shoreline. It is necessary to develop a technique to predict terrain change that reproduces the erosion and accumulation of estuarine deposits. To determine the parameters and variables necessary to reproduce this system, continuous on-site monitoring is necessary. The existing research did not fully examine the terrain changes in Nakdong River Estuary or the periodic developmental characteristics. To understand the future process of estuary delta development, it is necessary to establish an integrated management system.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.3
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• pp.527-532
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• 2020

In this paper, we presented the results of analysis through EEG measurement for the purpose of checking the frequency band of EEG signals that can be used for personal authentication. The measurement status was divided into the open-eye state and the closed-eye state depending on the presence or absence of an optical task. The data measured in the EEG experiments was divided into seven frequency bands : delta waves, theta waves, alpha waves, SMR waves, mid-beta waves, beta waves and gamma waves to identify the frequency band with the smallest power fluctuation over time. In our results, there was no significant difference between the open-eye state and the closed-eye state, and the SMR waves and mid-beta waves related to human concentration had the smallest fluctuation in power over time, and were a highly reproducible frequency band.

• Biomolecules & Therapeutics
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• v.7 no.3
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• pp.242-248
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• 1999

Diazepam, a benzodiazepine (BDZ) agonist, produces sedation and flumazenil, a BDZ antagonist, blocks these actions. The aim of this study was to examine the effects of BDZs on cortical electroencephalogram (EEG) in rats. The recording electrodes were implanted over the frontal and parietal cortices bilaterally, and the reference and ground electrodes over cerebellum under ketamine anesthesia. To assess the effects of diazepam and flumazenil, rats were injected with diazepam (1 mgHg, i.p.) and/or flumazenil ( 1 mg/kg, i.p.), and the EEG was recorded before and after drugs. Normal awake had theta peak in the spectrum and low amplitude waves, while normal sleep showed large amplitude of slow waves. The powers of delta, theta and alpha bands were increased during sleep compared with during awake. Diazepam reduced the mobility of the rat and induced sleep with intermittent fast spindles and large amplitude of slow activity, and it produced broad peak over betaL band and increased the power of gamma band, which were different from EEG patterns in normal sleep. Saline injection awakened rats and abolished fast spindles for a short period about 2-5 min from EEG pattern during diazepam-induced sleep. Flumazenil blocked both diazepam-induced sleep and decreased the slow activities of delta, theta, alpha and betaL, but not of gamma activity for about 10 min or more. This study may indicate that decrease in power of betaL and betaH bands can be used as the measure of central action of benzodiazepines, and that the EEG parameters of benzodiazepines have to be measured without control over the behavioral state by experimenter.

• Science of Emotion and Sensibility
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• v.6 no.1
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• pp.47-53
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• 2003

This study is an experimental study about the relationship between EEG and personality dimensions. Subjects were 70 healthy undergraduate students (32 males, 38 females) The Korean version of Eysencks Personality Questionnaire-Revised (EPQ-R) were used. EEGs were recorded in two different conditions (eyes open and eyes closed). To obtain more tellable data, EEG recordings of subjects were replicated 6 weeks later. The analytical methods used in the present study rendered two coincident tendencies: Theta with neuroticism relationship in eyes closed condition, and alpha-delta with psychoticism relationship in eyes closed condition. These results generally support the theory of Robinson (2001) that delta, theta, and alpha waves are associated with activity of brainstem, limbic system, and thalamo-cortical arousal system, and that thalamo-cortical alpha system has inhibitory effects on brainstem delta system.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.6
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• pp.526-534
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• 2022

The modular multilevel converter (MMC) has been widely applied to various industrial areas because of its various advantages and structural characteristics. Therefore, many methods for synthesizing the output voltage of MMC have been studied. Among these methods, phase-shifted pulse width modulation (PSPWM) is frequently used in MMC systems because it has diverse merits, such as excellent output qualities even with a small number of cells and uniform power distribution among cells. In this study, the total harmonic distortion (THD) of the output voltage is analyzed in accordance with the number of cells in one arm of a single-delta bridge cell MMC in order to compare PSPWM methods in terms of the THD of the output voltage. The physical characteristics of the triangle and sawtooth carrier waves used for the PSPWM and the mathematical modeling of output voltage are introduced. Then, the obtained results are verified through real-time simulation of a 1 MW single-delta bridge cell MMC system.

• Proceedings of the Korean Society of Food Science and Nutrition Conference
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• 2001.12a
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• pp.38-47
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• 2001

L-theanine is a unique amino acid, found almost solely in tea plants. It is the main component responsible for the exotic taste of green tea. In our studies of L-theanine, we have found a variety of biological activities including relaxation and the alleviation of PMS. In general, animals generate very weak electric pulses on the surface of the brain, called brain waves. Brain waves are classified into four types, namely $\alpha$, $\beta$, $\delta$ and $\theta$-waves, based on their frequency. Brain waves correlate with individual mental conditions. For example, generation of $\alpha$-waves is considered an index of relaxation. In human volunteers, $\alpha$-waves were generated on the occipital and parietal regions of the brain surface within 40 minutes after the oral administration of 50 or 200 mg Suntheanine$^{TM}$ without causing drowsiness. Premenstrual Syndrome (PMS) is a symptom unique to women which appears in the luteal phase from the ovulation period through the first day of menstruation. It possesses characteristics of having a peak just prior to menstruation and disappearing 1 - 2 days following the start of menstruation. Symptoms of PMS are generally categorized as mental, physical and social symptoms. When comparing the reported Symptoms of PMS by the methods of MDQ score, the Suntheanine$^{TM}$ group was found to have a lower incidence of PMS symptoms, including physical, mental and social symptoms. Overall, a significant alleviation of PMS symptoms by the administration of 200 mg Suntheanine$^{TM}$ was observed. With the successful industrial production of L-theanine, we are now able to supply Suntheanine$^{TM}$, offering a tremendous opportunity for designing functional foods targeting relaxation and the alleviation of PMS.

• Journal of the Korean Geophysical Society
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• v.2 no.3
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• pp.191-200
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• 1999

Analysis of chirp high-resolution seismic profiles from the central Yellow Sea reveals that depositional environments in this area can be divided into three distinctive zones from west to east: (1) subaqueous delta system near the Shandong Peninsula, (2) erosional zone in the central Yellow Sea, and (3) tidal sand ridges and sand waves near the Korean Peninsula. The Shandong subaqueous delta, extending southward from the Shandong Peninsula, changes gradually into prodelta southeastward. The sediments originated from the Yellow River are transported southward along the Chinese coastal area. The erosional zone in the central Yellow Sea contains numerous paleochannels and shows linear erosional features trending northwest-southeast. The erosional zone would be dominated by non-depositional or erosional processes during the Holocene. Tidal sand ridges and sand waves are well developed along the western coast of Korea. The residual sands, which were originally fluvial sediments at the sea-level lowstand, are interpreted as the result of winnowing process during the sea-level rise. Modern sand ridges generally migrates in a northeast-southwestern direction, which coincide with dominant tidal current direction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.482-492
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• 2019

This study began with the assumption that the phonetics-centered interpretation of 100 Chinese characters would enhance thinking ability and comprehension. For this purpose, two experimental groups and a comparative group were recruited from the graduate students from June 3, 2017 to February 22, 2018. The experimental group participated in the phonetics-centered Chinese character lecture for 4 hours per week for 6 weeks for a total of 24 hours. QEEG were measured before and after the phonetics-centered Chinese character lecture. A total of 18 subjects ( nine subjects in the experimental group and nine comparative subjects) were included in the study, and the difference between before and after the QEEG of the experimental and comparative groups was analyzed, respectively. The conclusions drawn from this study are as follows. First, the Chinese character lecture changed brain waves. Second, the LORETA analysis before and after the lecture in the experimental group significantly decreased the delta wave in the brain region (Broadmann 40) associated with the meaning of language and phonology. This study result is meaningful because it shows the significant changes of EEG via the lecture.

• Korean Journal of Acupuncture
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• v.26 no.2
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• pp.15-25
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• 2009

Objective: This paper aimed to understand influences on EEG conducting acupuncture stimulation, by comparing the changes in the acupoints on the body before and after normal people are treated with acupuncture at PC9 and TE3, which are referred to as Wood points(木穴), and PC5 and TE1, which are referred to as the Metal points(金穴) among the five shu points of Yin pericardium Meridian and Yang Triple Energizer Meridian. Methods: The study was performed on 30 healthy female volunteers in their 20's. EEG was measured for 5 minutes before acupuncture stimulation was conducted on PC9, TE3, PC5 and TE1. During 20 minutes of acupuncture treatment, the same items were continuously measured to find out whether there were any changes in them, and they were measured for 5 minutes after removing the acupuncture needles in order to implement a comparative analysis. Results: Comparision of EEG data before and after the treatment at PC9 shows no significant differences in all wave. Compared with the pre-acupuncture period at TE3, $\delta-\theta$ wave decreased significantly (P<0.05) during the acupuncture stimulation periods. Compared with the pre-acupuncture period at PC5, $\delta-\theta$ wave and high $\alpha$ wave increased significantly (P<0.05) during the acupuncture stimulation periods. And Mid $\beta$ wave and high $\beta$ wave decreased significantly (P<0.05) during the acupuncture periods and the post acupuncture periods. Compared with the Pre-acupuncture period at TE1, $\delta-\theta$ wave, $\theta$ wave and high $\alpha$ wave increased significantly (P<0.05) during the acupuncture stimulation periods. And Low $\beta$ wave decreased significantly (P<0.05) during the acupuncture periods. Conclusion: When acupuncture stimulation was performed on PC9 and TE3, referred to as the "Wood points", brain waves were stabled, while when acupuncture was performed on PC5 and TE1, called the "Metal points", a brain was waked. From the findings of this study, we hypothesize that the wood properties, from which growing starts in all things, are related with fast waves of EEG, and the metal properties, which stabilize and converge in all things, are related with slow waves of EEG.