• Annals of Clinical Neurophysiology
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• 제4권1호
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• pp.28-33
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• 2002

Backgrounds and objective : EEG reflect dynamic changes of continuous neuronal activities by internal and external stimuli. The aim of this study is to quantify nonlinearly the local dynamic differences among EEG data corresponding to different states of brain. Methods : EEG was recorded from twelve healthy normal subjects(mean age, 29.7 years; 8 men and 4 women) using digital EEG machine. 18-channel EEG data were selected during eyes closed(EC), eyes open(EO), and mental arithmetic(MA) in each subject. Correlation dimension(D2) and largest Lyapunov exponent(LLE) were calculated from three states and average value was mapped 2 dimensionally and compared with each other. Results : The distribution of D2 was relatively symmetric and its value was higher in frontal than in parieto-occipital region during EC. These findings were reversed during EO. Bilateral centro-temporo-parietal region showed high D2 value in MA compared with those in EC, which was more prominent in left side. LLE was larger than zero in all state and showed significant differences among EC, EO and MA(p=0.000). Conclusion : These results suggest that nonlinear analysis of EEG can quantify dynamic state of brain.

• 대한수학회지
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• 제55권6호
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• pp.1359-1380
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• 2018

In this paper, we prove that if a metric measure space satisfies the volume doubling condition and the Hardy type inequality with the same exponent n ($n{\geq}3$), then it has exactly the n-dimensional volume growth. Besides, three interesting applications of this fact have also been given. The first one is that we prove that complete noncompact smooth metric measure space with non-negative weighted Ricci curvature on which the Hardy type inequality holds with the best constant are isometric to the Euclidean space with the same dimension. The second one is that we show that if a complete n-dimensional Finsler manifold of nonnegative n-Ricci curvature satisfies the Hardy type inequality with the best constant, then its flag curvature is identically zero. The last one is an interesting rigidity result, that is, we prove that if a complete n-dimensional Berwald space of non-negative n-Ricci curvature satisfies the Hardy type inequality with the best constant, then it is isometric to the Minkowski space of dimension n.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제25회 KOSCI SYMPOSIUM 논문집
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• pp.1-9
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• 2002

Simultaneous PIV and OH PLIF measurements are used for shear strain rates and flame locations, respectively. It is believed that the shear strain rates represent flow characteristics such as turbulence intensity and the OH intensity indicates the flame characteristics such as burning velocities. However, these are still lack of geometric information, which may be very important to flame quenching Hence, fractal dimensions 'Df) of the OH images are adopted as an additional information. Finally, the flame structure diagram proposed in this research has three parameters, which consist of strain rates, OH intensities and fractal dimensions. The results show that this diagram classifies turbulent premixed flames more effectively based on flame structures. The regime of weak turbulence is limited to narrow strain ranges and has the fractal dimension of about 2 In the regime of moderate turbulence, OH intensities increase as strain rates increase and the values of fractal dimensions are 1.8 Df 1.95. The regimes of thickened reaction and flame extinction (quenching) show bell-shaped and their values of fractal dimensions are 1.5 Df 1.7 and 0.9 Df 0.6, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.315-318
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• 1988

PHOTO-RESIST 자체문제로인해 감소되는 최소해상력, 촛집심도여유 및 CRITICAL DIMENSION (C.D.) 조정여유도등을 연구하였다. 기존에 사용중인 PHOTO-RESIST(큰 분자량)와 PHOTO-RESIST자체내에 CONTRAST 촉진 물질(CEM)이 첨가된것(INNER CEM TYPE) 및 PHOTO-RESIST구성성분중 작은 분자량/좁은 분자량 산포가 형성된 RESIN 의 PHOTO-RESIST(LOW MOLECULAR WEIGHT CONTROL TYPE)등 세가지 PHOTO-RESIST를 사용 하여 상기의 항목을 분석하였다. INNER CEM TYPE 및 LOW MOLECULAR WEIGHT CONTROL TYPE의 PHOTO-RESIST는 기존에 사용중인 RESIST보다, 최소 RESOLUTION은 약 0.2 - 0.3 um, DEPOCUS MARGIN은 약 0.8 - 1.2 um 및 C.D. CONTROL LATITUDE 향상된 것 등이 우수하였다.

• 한국포장학회지
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• 제15권1호
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• pp.7-16
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• 2009

The purpose of this study was to evaluate current packaging modules and design the most acceptable packaging module for domestic and international distribution systems. An optimum packaging module can reduce package costs as well as total distribution costs such as transport, materials handling and warehouse costs. Three different sizes of packaging modules, namely U-type($600{\times}500\;mm$), K -ype($550{\times}366\;mm$) and I-type($600{\times}400\;mm$), were evaluated in terms of the area efficiency and MOEs(measures of effectiveness) for the T-11($1100{\times}1100mm$) and T-12($1,200{\times}1,000\;mm$) pallets. The results showed that the U-type module could fit very well for both pallets and the area efficiency of each module was more than 99 percents. Area efficiency of K-and I-type modules was greatly affected by the pallet footprint dimensions. U-type module also performed better result from MOEs evaluation. Twenty sub-multiple sizes derived from the U-type module were suggested for the future development of the Korean and ISO standards on dimension of transport packages.

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.531-537
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• 2014

Through-silicon vias (TSVs) are fine, deep holes fabricated for connecting vertically stacked wafers during three-dimensional packaging of semiconductors. Measurement of the TSV geometry is very important because TSVs that are not manufactured as designed can cause many problems, and measuring the critical dimension (CD) of TSVs becomes more and more important, along with depth measurement. Applying white-light scanning interferometry to TSV measurement, especially the bottom CD measurement, is difficult due to the attenuation of light around the edge of the bottom of the hole when using a low numerical aperture. In this paper we propose and demonstrate four bottom CD measurement methods for TSVs: the cross section method, profile analysis method, tomographic image analysis method, and the two-dimensional Gaussian fitting method. To verify and demonstrate these methods, a practical TSV sample with a high aspect ratio of 11.2 is prepared and tested. The results from the proposed measurement methods using white-light scanning interferometry are compared to results from scanning electron microscope (SEM) measurements. The accuracy is highest for the cross section method, with an error of 3.5%, while a relative repeatability of 3.2% is achieved by the two-dimensional Gaussian fitting method.

• The Journal of Asian Finance, Economics and Business
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• 제7권2호
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• pp.131-141
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• 2020

This study examines the poverty indicators in Northeast region of Thailand by adopting the global Multidimensional Poverty Index (MPI) methodology and the national survey of Minimum Basic Needs (MBN) of Thailand. Data are collected from three different districts in Khon Kaen province namely: Khok Po Chai, Sam Sung, and Nam Pong. The sample size is 187 households. Data analysis uses Ordinary Least Square (OLS) regression approach and includes 7 dimensions of poverty (health, environment, education, economy, Thai value, asset? empowerment, and digital literacy) with a total of 41 indicators. This study has found that poverty indicators in Khon Kaen province remains centered around the aspects of health and employment dimensions. While a change of family structure in the Thai society since 1960s reduces the family size, household saving substantially increases over the years. The effects of health dimension in poverty, on the other hand, appears on the other poverty dimension of Thai value, which include (1) a bad living habit of head of household (smoke or alcohol consumption) that links with illness and disease, (2) religious practice, and (3) chronic illness. Lastly, there are income gaps of different careers in the area, which suggests the issue of income inequality.

• Wind and Structures
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• 제22권5호
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• pp.573-594
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• 2016

Simultaneous pressure measurements on 2D square prisms with various corner modifications were performed in uniform flow with low turbulence level, and the testing Reynolds numbers varied from $1.0{\times}10^5$ to $4.8{\times}10^5$. Experimental models were a square prism, three chamfered-corner square prisms (B/D=5%, 10%, and 15%, where B is the chamfered corner dimension and D is the cross-sectional dimension), and six rounded-corner square prisms (R/D =5%, 10%, 15%, 20%, 30%, and 40%, where R is the corner radius). Experimental results of drag coefficients, wind pressure distributions, power spectra of aerodynamic force coefficients, and Strouhal numbers are presented. Ten models are divided into various categories according to the variations of mean drag coefficients with Reynolds number. The mean drag coefficients of models with $B/D{\leq}15%$ and $R/D{\leq}15%$ are unaffected by the Reynolds number. On the contrary, the mean drag coefficients of models with R/D=20%, 30%, and 40% are obviously dependent on Reynolds number. Wind pressure distributions around each model are analyzed according to the categorized results.The influence mechanisms of corner modifications on the aerodynamic characteristics of the square prism are revealed from the perspective of flow around the model, which can be obtained by analyzing the local pressures acting on the model surface.

• 대한화학회지
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• 제40권6호
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• pp.401-408
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• 1996

일반적으로 고온 초전도체들은 2차원적인 구조를 가지고 있으며, 2차원적인 구조가 초전도 물성과 어떠한 관계를 갖는가를 이해하는 것은 매우 중요하다. 본 논문에서는 초전도체 속의 전자기체를 기체분자운동론을 사용하여 각 차원에서의 상태 방정식을 유도하였으며, 그 기체가 액화될 때의 온도, 임계온도를 구하였다. 그 결과 전자의 자유도를 제한시킴에 따라 임계온도가 상승함을 알 수 있었다. 이것은 2차원적인 구조물질에 1차원적인 전자유통 경로가 있을 경우 여러가지의 임계온도를 가질 수 있음을 의미한다.

• Structural Engineering and Mechanics
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• 제23권2호
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• pp.147-161
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• 2006

Recent developments in fractal theory suggest that fractal may provide a more realistic representation of characteristics of cementitious materials. In this paper, the roughness of fracture surfaces in cementitious material has been characterized by fractal theory. A systematic experimental investigation was carried out to examine the dependency of fracture parameters on the aggregate sizes as well as the loading rates. Three maximum aggregate sizes (4.76 mm, 12.7 mm, and 19.1 mm) and two loading rates (slow and fast loading rate) were used. A total of 25 compression tests and 25 tension tests were performed. All fracture parameters exhibited an increase, to varying degrees, when aggregates were added to the mortar matrix. The fracture surfaces of the specimens were digitized and analyzed. Results of the fractal analysis suggested that concrete fracture surfaces exhibit fractal characteristics, and the fractal geometry provide a useful tool for characterizing nonlinear fracture behavior of concrete. Fractal dimension D was monotonically increased as maximum aggregate sizes increase. A new fractal fracture model was developed which considers the size and shape of aggregate, and the crack paths in the constituent phases. Detailed analyses were given for four different types of fracture paths. The fractal fracture model can estimate fractal dimension for multiphase composites.