• Journal of IKEEE
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• v.22 no.4
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• pp.1109-1114
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• 2018

Electroencephalogram (EEG) is a tool used to study brain activity caused by external stimuli. In this process, artifacts are mixed and it is easy to distort the signal, so post-processing is necessary to remove it. Independent Component Analysis (ICA) is a widely used method for removing artifact. This method has a disadvantage in that it has excellent performance but some loss of brain wave information. In this paper, we propose a method to reduce EEG information loss by restricting the filter coverage using eye blink information obtained from Eyetracker. We then compared the results of the proposed method with the conventional method using quantization methods such as Signal to Noise Ratio (SNR) and Spectral Coherence (SC).

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.2
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• pp.112-124
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• 2010

Studies that can find resolutions to problems of subjective psychiatric analysis must be performed and indeed they are in the process. However there still lies many problems in researches of mentality examination, which should be the foundation of finding potential resolutions. One of the biggest problems in the conventional system is that there are many different opinions by psychiatrists depending on their educations and experiences. There is no objective standard on the subjects and there is no effective psychiatric analysis method. Also, the characteristic of such examinations is that it cannot be applied to disabilities, foreigners and infants alyce the examination is ch examinconversation. The objective of this atudy is to standardize TAT(Thematic Apperception Test)analysiBallken index method so that subjective data from the examination can be excluded and the examination thus maklysithe examination objectified. Furthermore, objective result and patients' brain wave pattern is read with BCI(Brain Computer Interface) ch exaTherenvironment to Alsare it to brain wave characteristics vectors to reate brain-wave characteristics vector DB. Therefore, such DB can be utilize durlysithe examination and diagnosis to reate objective examination method and standardized diagnosis system. Thus, mentality examination can be performed only with brain-wave scans with BCI based TAT system.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1997.11a
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• pp.199-204
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• 1997

뇌전위에서 개인차가 없는 일반적인 규칙을 지닌 두 개의 정보 변수, 즉 ILF와 LHF 를 발견하였다. 이러한 일반성을 지닌 정보 변수가 청각, 후각, 촉각 자극에 의해 유발된 쾌하거나 불쾌한 감성 상태를 구분할 수 있으며 전두엽에서 그 경향이 두드러짐을 확인하였다. 전두엽의 뇌전위에서 감성 자극이 주어지기전과 자극이 주어지는 동안의 ILF, IHF값을 정규화함으로써 새로운 변수, Relative Quantified Emotional State(RQES)을 구현하였다. RQES는 쾌, 중립, 불쾌한감성의 정도를 선형적으로 정량화하였다. 따라서 하나의 전극으로 측정한 전두엽부분의 뇌전위로부터RQES 값을 계산하면 인간의 쾌, 불쾌 감성을 신뢰도있게 정량화 할 수 있다.

• Korean Journal of Biological Psychiatry
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• v.4 no.1
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• pp.67-73
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• 1997

The changes of electroencephalogram(EEG) in patients with dementia are most commonly studied by analyzing power or magnitude in certain traditionally defined frequency bands. However because of the absence of an identified metric which quantifies the complex amount of information, there are many limitations in using such a linear method. According to chaos theory, irregular signals of EEG can also result from low dimensional deterministic chaos. Chaotic nonlinear dynamics in the EEG can be studied by calculating the correlation dimension. The authors have analyzed EEG epochs from three patients with dementia of Alzheimer type and three matched control subjects. The multichannel correlation dimension is calculated from EEG epochs consisting of 15 channels with 16,384 data points per channel. The results showed that patients with dementia of Alzheimer type had significantly lower correlation dimension than non-demented controls on 12 channels. Topographic analysis showed that the correlation dimensions were significantly lower in patients with Alzheimer's disease on frontal, temporal, central, and occipital head regions. These results show that brains of patients with dementia of Alzheimer type have a decreased complexity of electrophysiological behavior. We conclude that the nonlinear analysis such as calculating correlation dimension can be a promising tool for detecting relative changes in the complexity of brain dynamics.

• Korean Journal of Biological Psychiatry
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• v.5 no.1
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• pp.95-101
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• 1998

The changes of electroencephalogram(EEG) in patients with dementia of Alzheimer's type are most commonly studied by analyzing power or magnitude in traditionally defined frequency bands. However because of the absence of an identified metric which quantifies the complex amount of information, there are many limitations in using such a linear method. According to the chaos theory, irregular signals of EEG can be also resulted from low dimensional deterministic chaos. Chaotic nonlinear dynamics in the EEG can be studied by calculating the largest Lyapunov exponent($L_1$). The authors have analyzed EEG epochs from three patients with dementia of Alzheimer's type and three matched control subjects. The largest $L_1$ is calculated from EEG epochs consisting of 16,384 data points per channel in 15 channels. The results showed that patients with dementia of Alzheimer's type had significantly lower $L_1$ than non-demented controls on 8 channels. Topographic analysis showed that the $L_1$ were significantly lower in patients with Alzheimer's disease on all the frontal, temporal, central, and occipital head regions. These results show that brains of patients with dementia of Alzheimer's type have a decreased chaotic quality of electrophysiological behavior. We conclude that the nonlinear analysis such as calculating the $L_1$ can be a promising tool for detecting relative changes in the complexity of brain dynamics.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2177-2178
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• 2006

학습 행동에서의 뇌파 측정은 실시간으로 두뇌 기능 상태를 연구하는데 유용한 연구 방법이며 대뇌의 부위 중 전두엽은 새로움에 대한 지향 반응과 사고 활동에 중요한 역할을 한다. 본 연구에서는 중학교 2학년 학생에게 새로운 시청각 학습 자료를 제시하고 5회의 반복학습이 이루어지는 과정에서의 전두부($Fp_2,Fp_2$)의 뇌파를 측정하고 Fourier, Wavelet 변환을 하여 정량적으로 분석하였다. 주의 집중, 정서 등 인지와 관련지어 특정파의 조절 능력 및 파의 특성을 이용한 여러 연구들을 종합해보면, 기억력, 주의지속과 연관되어 알파파, 베타파와 세타파가 발생되는 것을 볼 수 있다. 이 중 알파파는 기존의 뇌 상태를 동기화시키고 주의나 기억의 과정에 영향을 미칠 수 있는 것으로 증명되었다. 본 논문에서는 신호 처리에 높은 효율을 보이는 Wavelet 변환을 이용하여, 학습이 됨에 따라 변화하는 EEG 신호 가운데 알파파의 패턴과 활성도를 분석하고자 한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.536-547
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• 2020

This study analyzed the correlation between adolescents' smartphone addiction as well as depression, self-esteem, and self-regulation based on QEEG (Quantitative Electroencephalogram) analysis. The study period was from March 19 to July 12, 2019, and the subjects were 76 students at P Middle School in Gyeonggi-do (normal group 47, risk group 29) who filled out a questionnaire and were subjected to quantitative EEG. The data analysis was performed via frequency analysis, independent t-test, correlation analysis, and path analysis of the IBM SPSS Statics 21.0 program. First, smartphone addiction had a positive correlation with depression. Second, smartphone addiction showed a negative correlation with self-esteem and α wave. Third, depression showed a negative correlation with self-esteem, which did not show a significant correlation with self-regulation. Fourth, depression was higher in the risk group than the normal group. For self-esteem, the normal group scored higher than the risk group. Self-regulation showed higher significant differences with the normal group than the risk group. Fifth, for α wave and SMR, the normal group scored higher than the risk group. Sixth, α waves had a negative effect on smartphone addiction. This study is meaningful in that it applied a brain science approach using quantitative analysis for objective evaluation of smartphone addiction.

• The Korean Journal of Pharmacology
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• v.32 no.3
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• pp.293-300
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• 1996

During the development of hepatic encephalopathy after thioacetamide (TAA) injection to rat, EEG was recorded at two different states: without or with tactile stimulation of tail at regular intervals. Calculations based on the spectral and band analysis were used. The changes in the power spectra and bands were examined in 3 different behavioral stages: normal, mild ataxia and severe ataxia. In normal rats, the stimulation produced the increase in the power of the theta $(3.5{\sim}8\;Hz)$ and the gamma $(30{\sim}50\;Hz)$ bands. These changes could not be produced in rats with the mild and severe ataxia. The changes in the power of the theta band occurred earlier than those of the beta3 and the gamma bands in the stimulated state. Gradual decreases in the spectral power of the beta3 $(21{\sim}30\;Hz)$ and the gamma bands were correlated with the progress of the stages from normal condition to mild to severe ataxia in both unstimulated and stimulated states. The results indicate that the spectral and band analysis used in this study can quantify the severity of the neurological malfunction during HE.

• The Journal of the Korea Contents Association
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• v.12 no.7
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• pp.261-272
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• 2012

This study was conducted so as to examine which change tDCS (Transcranial Direct Current Stimulation) for improving working memory can make on the EEC of stroke patients. Among the patients who suffered for more than 6 months by hemiparalysis caused by stroke, 20 patients selected by MMSE and DST were randomly divided into I group (10 patients) fulfilled by only CCT and II group (10 patients) fulfilled by both tDCS and CCT for total 4 weeks, 30 minutes per a day, three times per a week. For examining EEC variation, the absolute spectrum power was calculated by three bands (${\theta}$; 4~8 Hz, lower ${\alpha}$; 8~10.5 Hz, upper ${\alpha}$;10.5~13 Hz) during the task of words, photos and mental calculation with EEC test, before the arbitration, after 2 weeks and after 4 weeks, so the rate of increase and decrease (%) for the reference EEC was obtained. As the results, the first, particular aspects different one another in three bands were detected according to the measuring period and task. The second, in the forth week, there was only a significant difference in lower ${\alpha}$-power of all tasks. Therefore, through the procedure measuring EEC of this study, the degree of working memory's damage can be expressed by numerical value and tDCS should be additionally helpful for brain damaged patients' perception rehabilitation.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.11a
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• pp.236-241
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• 2000

가상환경 하에서의 임장감을 객관적으로 계측하기 위한 방법으로 생체신호를 이용한 감성의 계측을 시도하였다. 여러 가지 가상환경 하에서 뇌파, 심전도, 호흡 등 다 채널의 생체신호를 계측하고 이때 피실험자가 느끼는 객관화된 임장감 지표들을 동시에 평가하여 이를 신경 회로망을 이용하여 분석하였다. 계측된 생체 신호를 사전 처리하여 일차적인 생체분석 지표들을 도출하고 이를 신경회로망의 입력으로 활용하였다. 임장감을 분석할 수 있도록 신경회로망을 학습시키고, 이를 이용하여서 가상환경 하에서 계측된 생체신호를 분석하여 임장감을 정량화하여 평가하였다.