수면파형의 독립성분분석

이일근,Lee, Il-Keun 대한수면의학회 2001 수면·정신생리 Vol.8 No.1

Independent Component Analysis (ICA) is a blind source separation method using unsupervised learning and mutual information theory created in the late eighties and developed in the nineties. It has already succeeded in separating eye movement artifacts from human scalp EEG recording. Several characteristic sleep waves such as sleep spindle, K-complex, and positive occipital sharp transient of sleep (POSTS) can be recorded during sleep EEG recording. They are used as stage determining factors of sleep staging and might be reflections of unknown neural sources during sleep. We applied the ICA method to sleep EEG for sleep waves separation. Eighteen channel scalp longitudinal bipolar montage was used for the EEG recording. With the sampling rate of 256Hz, digital EEG data were converted into 18 by n matrix which was used as a original data matrix X. Independent source matrix U (18 by n) was obtained by independent component analysis method ($U=W{\timex}X$, where W is an 18 by 18 matrix obtained by ICA procedures). ICA was applied to the original EEG containing sleep spindle, K-complex, and POSTS. Among the 18 independent components, those containing characteristic shape of sleep waves could be identified. Each independent component was reconstructed into original montage by the product of inverse matrix of W (inv(W)) and U. The reconstructed EEG might be a separation of sleep waves without other components of original EEG matrix X. This result (might) demonstrates that characteristic sleep waves may be separated from original EEG of unknown mixed neural origins by the Independent Component Analysis (ICA) method.

횡풍에 의한 주행 차량 위험도 해석

이일근,조병완 한국도로학회 2011 한국도로학회논문집 Vol.13 No.3

Travelling vehicles on roads may slip or overturn due to strong cross wind. This paper presents the path deviation equation and the overturning equation of vehicle, and the process of evaluating the cross wind risk. Case studies for cars and trucks are carried out. It explains the mechanism why the deviation occurs according to the types of vehicles. It shall help to prepare the measures for reducing the risk of travelling vehicles in high wind speeds. 도로를 주행하는 차량이 강풍구간을 지날 때 바람에 의한 횡력으로 경로를 벗어나 추돌사고를 일으킬 수 있다. 또한 높은풍속에서는 차량이 전도하면서 대형 사고를 유발할 수 있다. 본 연구에서는 우선 횡풍에 의한 차량의 경로이탈과 전도에 대한해석 매카니즘을 고찰하였다. 그리고 차량의 횡풍 위험도를 파악하기 위해 승용차와 트럭 등 10종의 대표 차량에 대한 위험도해석을 실시하였다. 또한 횡풍 위험도가 차량의 주행속도와 특성 등에 따라 많은 편차가 있으며, 편차 발생 원인을 분석하였다. 본 연구 결과는 강풍이 잦은 도로환경에서 주행안전성 확보 방안을 마련하기 위한 기초자료로 활용 가능할 것이다.

수면장애의 경제적 비용

이일근 대한수면연구학회 2012 Journal of sleep medicine Vol.9 No.1

The significance of sleep disorders is underestimated in our society. The number of sleep disorders is over 80 in recent classifications of sleep disorders. And the incidence and prevalence of sleep disorders are very high compared to other medical illnesses. The consequences of sleep disorders such as medical illness, surgical illness, and accident may cause serious burden not only to our individual health but also to our society both medically and socioeconomically. By reviewing economical cost of sleep disorders, we can see the seriousness of this condition and can find out what to do for the improvement to better condition.

뇌질환 증상 및 예방

이일근 국제뇌교육협회 2008 100세 시대 두뇌건강과 뇌교육 Vol.2008 No.4

콘크리트 구조물 단면복구공사 보수재료 품질기준개선

이일근,김기환,김홍삼,윤성환,김우석 대한토목학회 2023 대한토목학회논문집 Vol.43 No.1

For highway concrete structures, the deterioration of the structure is accelerated due to the increase in the use of deicing materials, andsectional repair work is being frequently carried out to restore performance. However, after the repair work, re-damage such as cracks,delamination, and poor bond performance is exhibited in the repaired sectional area. In this study, overseas repair materialrequirements were first analyzed, and present domestic requirements were improved repair material performance through field surveysof common concrete structures, laboratory experiments, and test construction on a disused concrete bridge. In addition, performance-based quality requirements were presented so that all materials that meet the required performance can be applied, and different testmethods for each material were unified into concrete test methods for consistent test results analysis. The considered performancerequirements were compression strength, bending strength, and bond strength for structural properties, and length change rate, crackresistance, thermal expansion coefficient, and elasticity coefficient were for dimensional behavior. For resistance to chloride penetrationresistance and freeze-thaw resistance were presented as durability. The proposed requirements for concrete repair materials areexpected to contribute to the improvement of the quality of concrete sectional repair work in Korea. 고속도로 콘크리트 구조물은 제설제 사용량 증가로 구조물의 열화가 가속되고 있어 성능회복을 위해 단면복구공사를 실시하고 있다. 하지만, 보수공사 이후 보수부위에 균열, 들뜸 및 부착성능 저하 등의 재손상이 나타나고 있다. 본 연구에서는 먼저 해외 기준을 분석하였고, 공용 중인 콘크리트 구조물의 현장조사, 실내실험, 폐교량에 대한 시험시공을 통해 균열 방지 및 부착성능향상을 위해 강화된 기준을 제시하였다. 요구성능이 충족되는 재료는 모두 적용이 가능하도록 성능기반의 품질기준을 제시하였고, 재료별 상이한 시험방법도 일관성 있는 시험결과 분석을 위해콘크리트 시험법으로 통일하여 제시하였다. 고려된 품질기준은 하중 저항을 위해 역학특성 분야로는 압축강도, 휨강도, 부착강도 기준을 마련하였고, 체적안정성을 위해 길이변화율, 균열저항성, 열팽창계수, 탄성계수를 기준을 마련하였다. 제설염해에 대한 저항성을 위해 내구성능 분야로는 염분침투저항성과 동결융해저항성 기준을 제시하였다. 본 연구에 의해 제시된 콘크리트 보수재료의 기준은 국내의 단면복구공사 품질향상에 기여할 것으로 기대된다.

Performance Analysis of Highly Effective Proposed Direction Finding Method

이일근,Rhee, Ill-Keun The Acoustical Society of Korea 1995 韓國音響學會誌 Vol.14 No.e1

The main purpose of this paper is to show the realizaability of the proposed highly effective direction finiding method which performs extremely well under the circumstances like low signal-to-noise ratio (S/N), very closely located signal sources, and so on. In order to achieve the purpose, the degree to which the proposed method is superior to the MUSIC(multiple signal classification) with respect to the S/N is discussed, and the result is analyzed in terms of the S/N and the number of sample data. 본 논문의 주된 목적은 주위 환경의 영향등으로 인하여 신호대잡음비(S/N)가 저하된 상황, 다중신호원들이 근접하여 위치한 상황등의 특수한 상황들에서도 고해상도를 지니는 도래방향각 예측방법의 개념적 S/N의 향상도를 이론적으로 증명하고 기존의 도래방향각 예측방법과 비교하므로서 제안된 방법의 실용화를 위한 이론적 타당성을 입증하는데 있다.

Direction Finding Problem에서의 신호원 갯수 추정 신뢰도에 관한 AIC와 MDL의 비교

이일근 한국통신학회 1990 韓國通信學會論文誌 Vol.15 No.10

본 논문에서는 array processing에서, sensor array를 통해 들어오는 source signal들의 개수를 결정하는 방법들을 판정의 정확도의 관점에서 연구 고찰한다. 첫번째 방법은 Akaike의 Akaike's Information Criterion(AIC)이고, 다른 하나는 Schwartz와 Rissanen의 Minimum Description Length(MDL)이다. 실용적인 측면에서 볼 때, 신호대잡음비 (S/N)가 매우 낮은 상태에서 얻어진 한정된 양의 data를 이용하여 제한된 갯수의 sensor들로 이루어진 array로 부터, 매우 근접해 있는 source signal들의 갯수를 예측해 내는 것은 대단히 중요한 일이다. 본 논문은 simulation 결과를 통하여, source signal들이 근접해 있을수록, array의 sensor 갯수가 줄어들수록, 이용할 data의 양이 한정될수록 또 S/N가 낮아질수록, AIC이 MDL에 비해서 높은 신뢰도를 가짐을 보여준다. In this paper, a couple of well-known methods for determination of the number of source signals impinging on sersor array in array processing are introduced and compared in terms of estimation accuracy. The one is the procedure issued by Akaike(Akaike's Information Criterion : AIC) and the other one by Schwartz and Rissanen(Minimum Description Length:MDL). This paper demonstrates, through computer simulation, that the AIC is more reliable than the MDL in such troublesome cases as very closely spaced source signlas, very limited number of sensors in the array, finite data sequences and/or low Signal-to-Noise ratio(S/N).

뇌파 전산 분석 및 비선형분석 소개

이일근 대한임상신경생리학회 2002 Annals of Clinical Neurophysiology Vol.4 No.2

Most of EEG information in clinical practice has been obtained from EEG waveform analysis by visual inspection. As digital EEG recording becomes popular in many hospital, computational analysis of EEG has been a new method for the analysis of clinical EEG. Among many computational tools for the manipulation of recorded EEG time series, linear methods such as frequency analysis, power spectral analysis, and other statistical analysis were applied at first. However, after the realization of the non-linear nature of biological signals, some researchers started to apply non-linear dynamics for the analysis of digital EEG data. Basic concept of non-linearity and chaos theory were reviewed in this article. And approach to chaotic system through several non-linear chaos parameters such as correlation dimension and largest Lyapunov exponent were followed; basic principles of chaos parameters, clinical application examples of the chaos parameters.

수면-각성 상태의 뇌파 비선형 지수 변화

이일근,강사윤,하충건 대한신경과학회 2000 대한신경과학회지 Vol.18 No.1

Q3. 수면제나 수면마취제를 사용했을 때의 뇌파는 자연 수면 시의 뇌파와 같을까?

이일근 한국뇌과학연구원 2021 브레인 Vol.87 No.-