• Journal of the Korea Concrete Institute
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• v.16 no.5 s.83
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• pp.581-589
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• 2004

This paper compares the fatigue behaviors of concretes subjected to flexural and split-tensional loadings, and proposes the fatigue reliability models based on experimental results and reliability analysis. The fatigue tests were performed for the specimens of $150 mm{\times}75 mm$ split tensional cylinders and $150 mm{\times}150 mm{\times}550 mm$ flexural beams under constant loadings at three levels (70, 80 and $90\%$) with 0.1 stress ratio, 20 Hz loading speed and sine wave. The reliability analysis on fatigue data was based on Weibull distribution of two-parameters. From fatigue test results, two criteria were proposed to reject the experimental fatigue data because of statistical variation of concrete fatigue data. Two parameters ($\alpha$and u) of Weibull distribution were obtained using graphical method, moment method and maximum likelihood method. The probability density function(P.D.F) and cumulative distribution function(C.D.F) of the Weibull distribution for fatigue life of pavement concrete were derived for various stress levels using parameters, $\alpha$ and u. The goodness-of-fit test by Kolmogorov-Smirnov test was acceptable at $5\%$ level of significance. Based on reliability analysis, a fatigue model for pavement concrete was proposed and compared from existing models.

• Journal of the Korean Magnetics Society
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• v.7 no.3
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• pp.140-145
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• 1997

The amorphous state of $NdFe_{10.7}TiB_{0.3}$ and its nanocrystallization have been studied by X-ray diffraction, 모스바우어 spectroscopy, and a vibrating sample magnetometer (VSM), $NdFe_{10.7}TiB_{0.3}$ amorphous ribbons were fabricated by a sigle-roll melt-spinning method. The average hyperfine field $H_{hf}$(T) of the amorphous state shows a temperature dependence of $[H_{hf}(T)-H_{hf}(0)]/H_{hf}(0)=-0.46(T/T_c)^{3/2}-0.34(T/T_c)^{5/2}$ for $T/T_c<0.7$ indicative of spin wave excitation. The quadrupole splitting just above the Curie temperature $T_c$ is 0.46 mm/s, whereas the average quadrupole shift below $T_c$ is zero. The Curie and crystallization temperatures are determined to be $T_c$=380K and $T_x=490K$, respectively, for a heating rate of 5 K/min. The occupied area of nanocrystalline phase at around 770K is about 65%. Above the Curie temperature, VSM data show magnetic moments increases again. The formation of $\alpha$-Fe is the main reason for the increasing moment as conformed with the 모스바우어 measurements.

• Journal of Oriental Neuropsychiatry
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• v.21 no.3
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• pp.45-64
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• 2010

Objectives : The purpose of this study was to examine the effects of auricular acupuncture at the Shinmun on patients with dementia by using power spectrum analysis. Electroencephalogram(EEG) power spectrum show site-specific and state-related differences in various frequency bands. Methods : Study was carried out in 38 subjects.(31 patients with dementia and 7 normal people, 27 females and 11 males ; mean age=75.9 years old). To know the effect of auricular acupuncture at the Shinmun in patients with dementia, we measured electroencephalogram(EEG) of normal people and patients with dementia about 'before', 'after' and 'after 15 minutes' giving auricular acupuncture at the Shinmun, and compared the brain wave($\alpha$, $\beta$, $\delta$, $\theta$) of EEG 30 channels. Results : In the case of patients with dementia, in the power values of $\alpha$(alpha) band at F4, FP2, FCZ, F8, FC4 channels (p<0.05) during the Shinmun-auricular acupuncture treatment increased significantly. In $\beta$(beta) band, the power values at T8 channel(p<0.05) during the Shinmun-auricular acupuncture treatment increased significantly. In $\delta$(delta) band, the power values at F7, FP1, FZ, FP2, FCZ, C4, FC4, CP4, T8, P7, P3, O1, OZ, O2, P4, P8 channels(p<0.05) during the Shinmun-auricular acupuncture treatment decreased significantly. In $\Theta$(theta) band, the power values at O1, OZ, O2channel(p<0.05) during the Shinmun-auricular acupuncture treatment decreased significantly. Conclusions : Through these results, we concluded that auricular acupuncture at the Shinmun on patients with dementia could have effect the functional mechanism of the cerebral cortex.

• Journal of the Mineralogical Society of Korea
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• v.23 no.4
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• pp.403-411
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• 2010

Essentials of understanding the geochemical evolution and geophysical processes in Earth's system are macroscopic properties and atomistic (and electronic) structures of Earth materials. Recent advances in quantum calculations based on the density functional theory allow us to unveil the previously unknown details of local atomic structures in diverse silicates in Earth's interior. Here, we report the O K-edge ELNES (energy-loss near-edge structure; ELNES) spectra and PLDOS (partial local density of states) for oxygen atoms in ${\alpha}$-quartz and stishovite using the quantum calculations based on FP-LAPW (full potential linearized augmented plane wave). The calculated O K-edge ELNES spectrum of ${\alpha}$-quartz shows a strong peak at ~538 eV due to comer-sharing oxygen linking two $SiO_4$ tetrahedra and that for stishovite shows two distinct peaks at ~537 and ~543 eV corresponding to edge-sharing oxygen linking $SiO_6$ octahedra. The significant differences in spectral features of O K-edge ELNES spectra suggest that the O K-edge features can be useful indicator to distinguish various oxygen sites in diverse crystal and amorphous silicates in the Earth's interior.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.11
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• pp.596-602
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• 2015

In this study, experiments using bioelectronic signals and questionnaire surveys were carried out in learning conditions when temperatures changed from low- and high-uncomfortable to comfortable. As a result, the stress factor Photoplethysmography (PPG) decreased, while the Root Mean Square of Standard Deviation (RMSSD) of PPG increased when the indoor temperature was changed from low- or high-uncomfortable to comfortable. Additionally, the absolute power of the ${\alpha}$-wave in the brain increased. According to the analysis of the association between the questionnaire and bioelectronic signals, the standard deviation of the stress factor as measured by pulse was closely related to the result of the thermal sensation questionnaire. In addition, it was found that the concentration on studying improved under comfortable temperatures when compared to uncomfortable temperatures.

• Journal of Biomedical Engineering Research
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• v.25 no.3
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• pp.227-233
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• 2004

In this paper, it is proposed that the four channel electrode arrangement at a frontal lobe and the noise reduction method using a JADE for the EEG biofeedback system. The proposed electrode arrangement is based on the retina-cornea dipole model. Using JADE and signals which are acquired by the proposed arrangement, four independent components are separated. To estimate a pure EEG component among four components, it is measured that a ratio of alpha wave to the whole signal and then the component that has a maximum value is considered as a pure EEG which the noise is eliminated. As a result of experiments, the proposed methods are effective in reduction of noises during acquisition of the EEG.

• Journal of Biomedical Engineering Research
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• v.25 no.3
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• pp.217-225
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• 2004

In this paper, a new automatic classification method for the normal EEC and schizophrenia EEC using hidden Markov model(HMM) is proposed. We used the feature parameters which are the variance for statistical stationary interval of the EEC and power spectrum ratio of the alpha, beta, and theta wave. The results were shown that high classification accuracy of 90.9％ in the case of normal person, and 90.5％ in the case of schizophrenia patient. It seems that proposed classification system is more efficient than the system using complicate signal processing process. Hence, the proposed method can be used at analysis and classification for complicated biosignal such as EEC and is expected to give considerable assistance to clinical diagnosis.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.88.2-88.2
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• 2013

Exploration of the wave-mode identification and its propagating property in the solar pore is desirable to study the energy transfer in the solar atmosphere. The Fast Imaging Solar Spectrograph (FISS) installed at the New Solar Telescope (NST) is a unique system that can do imaging of H-alpha and Ca II 8542 band simultaneously, which is quite suitable for studying of dynamics of chromosphere. In this study, we inspect a relationship between the cross-sectional area and intensity of the pore at continuum (-0.4 nm) near the Ca II line. We find coherent oscillations of the area and intensity. They shows out-of-phase (~ 180 degree difference) in photosphere, which implies that the oscillation is fast sausage mode. We also investigate a relationship between LOS velocities above the pore obtained from the Ca II and the Ha line cores, and find no significant difference of the phase (~10 degree) between the formation heights of the lines in chromosphere.

• Journal of radiological science and technology
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• v.41 no.3
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• pp.231-240
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• 2018

Automated breast ultrasound (ABUS) equipment is a new innovative technique for 3D automatic breast scanning, but limited for the examination in the concave axillary region. The purpose of this study was to determine feasible candidate materials for the ultrasonic wave propagation media in ABUS, enabling the evaluation of the axillary region. Ultrasonography was performed using an ABUS system ($Invenia^{TM}ABUS$, GE, USA) on the ultrasound-specific phantom (UC-551M-0.5, ATS Laboratories, USA) covered by different candidate materials. The validity of feasible candidate materials was evaluated by image quality. Three independent radiological technologists, with more than 10 years of experience, visually assessed on the images. The inter-observer agreements according to the candidate materials were tested using Cronbach's alpha. Unenveloped solidified carrageenan can be a feasible material for the use of ABUS with excellent test reliability. Therefore, the coverage of the axillary region with carrageenan may be effective for ABUS which was originally developed for the convex anatomic structure as female breast.

• 한국전산유체공학회:학술대회논문집
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• 2004.03a
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• pp.113-118
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• 2004

This paper presents a two-dimensional edge tone to predict the frequency characteristics of the discrete oscillations of a jet-edge feedback cycle by the finite difference lattice Boltzmann method (FDLBM). We use a new lattice BGK compressible fluid model that has an additional term and allow larger time increment comparing the conventional FDLBM, and also use a boundary fitted coordinates. The jet is chosen long enough in order to guarantee the parabolic velocity profile of the jet at the outlet, and the edge consists of a wedge with an angle of $\alpha=23^0$. At a stand-off distance $\omega$, the edge is inserted along the centreline of the jet, and a sinuous instability wave with real frequency f is assumed to be created in the vicinity of the nozzle and th propagate towards the downstream. We have succeeded in capturing very small pressure fluctuations result from periodically oscillation of jet around the edge. That pressure fluctuations propagate with the sound speed. Its interaction with the wedge produces an irrotational feedback field which, near the nozzle exit, is a periodic transverse flow producing the singularities at the nozzle lips. The lattice BGK model for compressible fluids is shown to be one of powerful tool for computing sound generation and propagation for a wide range of flows.