• Bulletin of the Korean Space Science Society
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• 1995.10a
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• pp.30-30
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• 1995

We present the results of analysis on the X-ray observations of the binary X-ray pulsar Her X-I. made with ASCA/SIS on August 13-14. 1993. An eclipse transition from ingress to egress was fully covered by the observations. The main findings are as follows; (1) a model of power-law plus black-body is required to interpret the entire eclipse spectrum. and the black-body component appears at < 0.7 keV. (2) the power-law continuum which has photon index ${\alpha}\;=\;{0.84^{\;+0.14}}_{\;-0.19}$ is very similar to that of detected by Ginga/LAC (${\alpha}\;=\;0.80\;{\pm}\;0.04$), (3) the calculated eclipse flux of $2^{-10}\;keV.{\;}~{\;}1.8{\pm}10^{-11}{\;}ergs{\;}cm^{-2}s^{-1}$, is consistent with the Ginga observation carried out in the high intensity state ~2.0{\pm}10^{-11}{\;}ergs{\;}cm^{-2}s^{-1}$, (4) there is no significant absorption feature. and an upper limit of the aborption column $NH{\;}\leq{\;}3{\pm}10^{20}\;cm^{-2}$ is determined at the 90% confidence limit. Based on these results, we suggest that extended matter surrounding the binary system should be existed persistently with stable conditions, and scattering of the source continuum by the matter is responsible for the eclipse emission.ission.

• Korean Journal of Optics and Photonics
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• v.18 no.3
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• pp.221-225
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• 2007

The possibility of improving amplification characteristics and lowering the melting point of bismuth-doped aluminosilicate glass as a new amplification material, which has broadband near-infrared emission at 1300 nm regions, was investigated. Spectroscopic analysis of bismuth-doped aluminosilicate glass shows that the addition of an alkali metal oxide, $Li_{2}O$ increases FWHM of fluorescence spectrum but decreases fluorescence intensity, while $GeO_{2}$ composition increases both FWHM of fluorescence spectrum and fluorescence intensity. Also, excellent optical amplification gain characteristics in a $GeO_{2}$-added sample were observed.

• Journal of Sensor Science and Technology
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• v.30 no.1
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• pp.47-50
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• 2021

Human hearing sensitivity is frequency-dependent. The sensitivity is low at both ends of the audible frequency, and the sensitivity is the highest in the middle band at 3000 Hz. The heart sound of a healthy person is concentrated at a low frequency of 200 Hz or less, and despite using a stethoscope, the hearing sensitivity of the human body is low, and the stethoscope sound is low. Amplifying the sound of the stethoscope is not effective in distinguishing heart sounds in noisy environments because it maintains the same signal-to-noise ratio. In this study, a method of enhancing auditory stimulation was developed by applying a method of moving the spectrum of auscultation sounds into a high-frequency region where the human body is highly sensitive to hearing. The spectrum of the auscultation sound was moved up by 500 Hz in the frequency domain, and an inverse fast Fourier transform (FFT) was performed to reconstruct the auscultation sound. The heart sounds reconstructed by moving the spectra were divided into the first heart and second heart sound components, as in the original heart sound, and it was confirmed that the intensity was large in the cochleagram representing auditory stimulation. Therefore, this study suggested that spectral shift is a method to enhance auditory stimulation during auscultation without increasing the intensity of the auscultation sound.

• Journal of the Earthquake Engineering Society of Korea
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• v.26 no.2
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• pp.95-103
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• 2022

In order to evaluate the earthquake safety of equipment in structures, it is essential to analyze the In-Structure Response Spectrum (ISRS). The ISRS has a peak value at the frequency corresponding to the structural vibration mode, but the frequency and amplitude at the peak can vary because of many uncertain parameters. There are several seismic design criteria for ISRS peak-broadening for fixed base structures. However, there are no suggested criteria for constructing the design ISRS of seismically isolated structures. The ISRS of isolated structures may change due to the major uncertainty parameter of the isolator, which is the shear stiffness of the isolator and the several uncertainty parameters caused by the nonlinear behavior of isolators. This study evaluated the effects on the ISRS due to the initial stiffness of the bi-linear curve of isolators and the variation of effective stiffness by the input ground motion intensity and intense motion duration. Analyzing a simplified structural model for isolated base structure confirmed that the ISRS at the frequency of structural mode was amplified and shifted. It was found that the uncertainty of the initial stiffness of isolators significantly affects the shape of ISRS. The variation caused by the intensity and duration of input ground motions was also evaluated. These results suggested several considerations for generating ISRS for seismically isolated structures.

• Journal of Broadcast Engineering
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• v.16 no.1
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• pp.14-22
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• 2011

The conventional satellite image fusion methods usually add the same amount of higher frequency components extracted from the panchromatic image to all the multispectral images. However, it is noted that each of multispectral images has different amount of overlap with the panchromatic image in terms of its spectrum, and also has different intensities. Thus giving the same amount of high frequency contents to all the spectral bands does not match with this observation, which causes color distortion in the fused image. In this paper, we propose a new wavelet-domain satellite image fusion algorithm that can compensate for these differences in intensity and spectrum overlap. For the compensation of intensity differences, we first estimate the high resolution multispectral images from P, considering the relative intensity ratios. For the compensation of the amount of spectral overlap, their wavelet coefficients are appended to the conventional wavelet-domain method where the coefficients for the addition is determined by the amount of spectrum overlap. Experiments are conducted for the IKONOS satellite images whose spectrums are well known, and the results show that the proposed algorithm gives higher PSNR and correlation coefficients compared to the conventional methods.

• Analytical Science and Technology
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• v.24 no.3
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• pp.168-172
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• 2011

The iron frame of building could be collapsed or bent at $500^{\circ}C$. Therefore the fire-resistant paint should be applied for safety. This study performed the comparative analysis to show the characteristics of fireresistant paint. And then 12 products of fire resistant paint and 6 products of paints were used as samples. And the samples were analyzed by TGA (Thermogravimetric Analyzer) as analyzer for measuring the variation of weight on temper of weight by heating. When TGA analyzer could measure the variatiature, and FT-IR was measured for analyze gas components on variation on of weight by heating on 12 products of fire resistance, the samples showed to decrease 40% of weight to $800^{\circ}C$, and because paints had 50% to 40% of loss weight, it showed to be equal with loss weight of fire resistance paint on high temperature or was lower loss weight than it of fire resistance paints. However number 6 sample of fire resistance paints could show to decrease 20% of total weight on $800^{\circ}C$. And then in the case of FT-IR, fire resistance paints could show to have the high intensity of $CO_2$ spectrum as complete combustion. However paints could show to have the lower intensity of $CO_2$ spectrum, have the higher intensity of water spectrum. Therefore the TGA graph of result could be much different until $250^{\circ}C$. When it was burned, FT-IR spectrum could show to confirm the characteristics of fire resistance paints, and the characteristic could be confirmed on inorganic paint of fire resistance by weight loss of TGA.

• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.543-546
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• 2004

The inverse Compton scattering of the cosmic microwave background (CMB) radiation with electrons in the intracluster medium which has a temperature gradient, was examined by the third-order perturbation theory of the Compton scattering. A new type of the spectrum distortion of the CMB was found and named as gradient T Sunyaev-Zel'dovich effect (gradT SZE). The spectrum has an universal shape. There is a zero distortion point, the cross over frequency, at 326GHz. When the hotter region locates closer to an observer, the intensity becomes brighter than the CMB in the frequency region lower than the cross over frequency and fainter than the CMB in the frequency region higher than the cross over frequency. When the cooler region locates closer to an observer, the distorted part of the spectrum has an opposite sign to the above case. The amplitude of the spectrum distortion does not de-pend on the electron density and depends on the heat conductivity and the total temperature variation along a line of sight. Therefore, the gradT SZE provides an unique opportunity to measure thermally nonequilibrium electron momentum distribution function in the ICM and combined with the X-ray measurements of the electron temperature distribution provides an opportunity of direct measurement of the heat conductivity in the ICM.

• Journal of Powder Materials
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• v.9 no.5
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• pp.341-345
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• 2002

Nanoparticles of $Fe_2O_3$ with a mean particle size of 4-30 nm have been prepared by a pulsed wire evaporation method, and its structural and magnetic properties were studied by SQUID magnetometer and Mossbauer spectroscopy. From the main peak intensity of XRD and absorption rate of Mossbauer spectrum, the amounts of $\gamma-Fe_2O_3$ and $\alpha-Fe_2O_3$ in as-prepared sample are about 70% and 30%, respectively. The coercivity (53 Oe) and the saturation magnetization (14 emu/g) are about 20% of those of the bulk $\gamma-Fe_2O_3$. The low value of coercivity and saturation magnetization indicate that the $\gamma-Fe_2O_3$ phase nearly shows the spin glass-like behavior. Analysis of the set of Mossbauer spectrum indicates a distribution of magnetic hyperfine fields due to the particle size distribution yielding 20 nm of average particle size. The magnetic hyperfine parameters are consistent with values reported of bulk $\gamma-Fe_2O_3$ and $alpha-Fe_2O_3$. A quadrupole line on the center of spectrum represents of superparamagnetic phase of $\gamma-Fe_2O_3$ with a mean particle size of 7 nm or below.

• Journal of the Korean Magnetics Society
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• v.21 no.1
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• pp.5-9
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• 2011

M$\ddot{o}$ssbauer and Raman spectrum studies have been carried out on the 2b-site Fe ion in the Ba-ferrite (M-type). The thermal dynamics of Fe ion was analyzed by M$\ddot{o}$ssbauer spectra at different angles between the $\gamma$-ray direction and c-axis. The vibration on the 2b-site was more active compare to other direction and had very strong intensity in the Raman spectrum.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.93.1-93.1
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• 2014

The reflection nebula NGC 7023 is a typical example of a photodissociation region (PDR), which consists of high density molecular gas that is exposed to an intense UV radiation field. The source of the UV photons in NGC 7023 is the young pre-main-sequence Be star HD 200755. We present our near-infrared high-resolution (R ~ 40,000) spectrum of NGC 7023, covering a region of $1{\times}15$ arcseconds, observed during the commissioning runs of IGRINS (Immersion GRating near-INfrared Spectrometer). The spectrum shows many strong narrow emission lines that arise from the molecular rovibrational transitions of H2. From the intensity ratios between these H2 lines, we investigate physical conditions within the PDR such as the temperature, density, and pressure. The high spectral resolution of IGRINS allows us to resolve the velocity field of the PDR. In addition, we compare the IGRINS spectrum to Cloudy PDR model.