• Journal of Biomedical Engineering Research
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• v.12 no.2
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• pp.79-88
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• 1991

Semi-transparent volume rendering technique can provide 3-D visualization well by voxel level Processing and alleviate segmentation arf, ifacts compared wish the surface rendering technique. In this Paper, we consider several new schemes which can improve she Perform ance of volume rendering. A directional interpolation method is proposed to reduce the artifact due to the anisotrophic resolution in X-ray CT data. The computation time for rendering is shortened by using the depth information of the 3-D object. And also, we reduce the quantization artifacts in the rendering by introducing the opacity-dependent sampling interval to sampling in ray-tracing.

• Journal of Astronomy and Space Sciences
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• v.5 no.2
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• pp.81-96
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• 1988

We have made new models for mass-losing OH/IR stars to explain the properties of the dust shells around them using more accurate information about the material in the shell and the physical precesses including pulsations. We have applied our dust opacity which has been deduced from observations and experimental data to various density distributions, calculated the model emergent spectra, and compared with observations. Contrary to previous suggestions, we could fit observations fairly well using density distribution $\rho\propto r^{-2}$, which is physically plausible, with proper choice of opacities. The time scales for dust formation, growth, and movement are calculated to be compared with pulsation periods. The change of the emergent spectrum depending on the phase of pulsation can be explained fairly well by changing dust condensation radius(for fixed dust condensation temperature) in step with the change in stellar luminosity. The effects of stellar wind models and pulsation models on dust shells with attention to emergent spectra are discussed.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.24.4-25
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• 2009

We have investigated the radiational fields through a hydrodynamical stellar model atmosphere. Stellar convection zone is the extremely turbulent region composed of partly ionized compressible gases in high temperature. Moreover, super-adiabatic layers are the transition region in energy transport from convection to radiation. Therefore, opacities and thermodynamic properties due to interaction of matter and radiational fields vary significantly with depth. In order to describe radiational fields accurately, the Opacity Distribution Function (ODF) and the Accelerated Lambda Iteration (ALI) have been applied to hydrodynamic medium. As the first result of our radiative transfer, we present time-dependant variation of radiational fields and thermodynamic structures. Our non-gray transfer model has been compared with the conventional Eddington Approximation. Detailed information of radiational fields and thermodynamic properties will provide deeper insight of physical processes inside stellar atmospheres.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.5
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• pp.1102-1110
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• 2005

In this paper, we proposed a advanced approach to resolve the trade-off problem for the threshold value determining the photo-consistency in the previous algorithms. The threshold value for the surface voxel is substituted the photo-consistency value of the inside voxel. As iterating the voxel coloring process, the threshold is approached to the optimal value for the individual surface voxel. we present an energy minimization formulation of the binary labeling problem that surface voxels classify into opacity or transparency. The energy formula consists of the data term and the smoothness term. As considering neighboring voxels in the labeling problem, the unevenness of reconstructed surface is reduced. The labeling whose energy is the global minimum can be computed using a graph cut.

• Journal of Preventive Medicine and Public Health
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• v.29 no.3 s.54
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• pp.471-482
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• 1996

Early recognition of coalescence in pneumoconiotic lesions is important because such coalescence is associated with the respiratory symptoms and deterioration of lung function. This complicated form of pneumoconiosis also has worse prognosis than does simple pneumoconiosis. High resolution computerized tomography(HRCT) provides significant additional information on the stage of the pneumoconiosis because it easily detects coalescence of nodules and emphysema that may not be apparent on the simple radiograph. The purpose of this study is to clarify the role of HRCT in detection of large opacity and the relationship of change between the coalescence of nodules or emphysema and lung function in dust exposed workers. 1. There was good correlation between the HRCT grade of pneumoconiosis and ILO category of profusion. 5(9.09%) in 55 study population had confluent nodule extending eve, two o, more cuts on HRCT. HRCT could identify the pneumoconiotic nodules which was not found by simple radiogrphy in 6 workers with category 0/0. 2. No significant difference was observed coalescence of nodules and emphysema by dust type. 3. There was no significant difference in pulmonary function according to ILO and HRCT classification. 4. HRCT could detect the significant reduction in $FEV_1,\;FEV_1/FVC$, PEFR, $FEF_{25},\;FEF_{50},\;and\;FEF_{75}$ and remarkable increase in RV and TLC in study persons with emphysema compared with non-emphysema group. 5. Emphysema was found more often in nodules-coalescence group than small opacity group by HRCT. We found that HRCT could easily detect areas of coalescence and complicated emphysema compared to plain chest X-ray. Also our data suggest that it is primarily the degree of emphysema rather than the degree of pneumoconiosis that determines the level of pulmonary function.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.36 no.4 s.107
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• pp.33-40
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• 2004

A white light interferometery (WLI) method for investigating surface microstructure was introduced. Brief description of the principle of this method was provided. The surface structure of various samples, for example, a liner board paper, a pigment coated paper, a intaglio printed paper and a polymer laminated paper were tested and characterized with the WLI method. The data showed the WLI method provided very detailed information about surface topography, which were little affected by the surface condition such as color, opacity, roughness, etc. The data stitching mode of the WLI method could provide high spatial resolution over a large field-of-view, which made it possible to obtain the statistically valid results. Fast and high repeatability also made this method a promising way for investigating the surface micro-structure of paper products and prints.

• Journal of The Korean Astronomical Society
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• v.36 no.spc1
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• pp.55-61
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• 2003

There are at least three effects of the non-thermal particle bombardment on the solar atmosphere: (1) non-thermal ionization and excitation; (2) proton-hydrogen charge exchange; (3) impact line polarization. Due to the non-thermal ionization and excitation effects of electron bombardments in flares, H$\alpha$ line is widely broadened and shows a strong central reversal. Significant enhancements at the line wings of Ly$\alpha$ and Ly$\beta$ are also predicted. In the case of proton bombardment, less strong broadening and no large central reversal are expected. However, due to proton-hydrogen charge exchange, the enhancements at the red wings of Ly$\alpha$ and especially of Ly$\beta$ lines at the early impulsive phase of flares are significant. Electron beam can also in some cases generates visible and UV continuum emission in white-light flares. However, at the onset phase, a negative 'black' flare may appear in several seconds, due to the increase of the $H^-$ opacity. The impact polarization of atomic lines can provide complementary information on the energetic particles, the energy transport and deposit in the solar chromosphere. New results of spectropolarimetric analysis for the major flare on July 23, 2002 are also given in the paper.

• Tuberculosis and Respiratory Diseases
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• v.45 no.3
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• pp.654-660
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• 1998

Pulmonary embolism is one of the moot common acute pulmonary disease in the adult general hospital population However, the disease is still frequently unsuspected and underdiagnosed due to the nonspecificity of both clinical findings and laboratory tests. The chest radiography in a patient suspected acute pulmonary embolism do not provide adequate information to establish or exclude the diagnosis of pulmonary embolism. Even in the case of infarction, there is no pathognomonic clues on the chest film. Rarely infarction presents unusual roentgenologic manifestation such as lobar consolidation, coin lesion, multinodular opacity, or massive pleural effusion Especially, lobar consolidation in pulmonary embolism might mislead into the diagnosis of pneumonia. We experienced a case of pulmonary embolism presenting lobar consolidation in a 62 years old woman, originated from deep vein thrombosis. She took a compression stocking and underwent anticoagulant therapy with excellent outcome.

• Journal of Astronomy and Space Sciences
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• v.24 no.1
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• pp.31-38
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• 2007

We have investigated the evolutionary status of 85 Peg within the framework of standard evolutionary theory. 85 Peg has been known to be a visual and spectroscopic binary system in the solar neighborhood. In spite of the accurate information of the total mass (${\sim}1.5M_{\odot}$) and the distance (${\sim}12pc$) from the HIPPARCOS parallax, it has been undetermined an individual mass, therefore the evolved status of the system. Moreover, the coupled uncertainties of chemical composition and age, make matters worse in predicting an evolutionary status of the system. Nevertheless, we computed the various possible models for 85 Peg, and then calibrated stellar parameters by adjusting to the recent observational data. Our modelling computation has included recently updated input physics and stellar theory such as opacity, equation of state, and chemical diffusion. Through a statistical assessment, we have derived a confident parameter set as the best solution which minimized $X^{2}$ within the observational error domain. Most of all, we found that 85 Peg is not a binary system but a triple system with an unseen companion 85 Peg $B_{b}\;{\sim}0.16M_{\odot}$. The aim of the present paper is (1) to provide a complete modelling of the stellar system based on the evolutionary theory, and (2) to constrain the physical dimensions such as mass, metallicity and age.

• Geophysics and Geophysical Exploration
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• v.6 no.1
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• pp.35-39
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• 2003

A software to visualize and analyse 3-D seismic data is developed using OpenGL, one of the most popular 3-D graphic library, under the PC and Windows platform. The software can visualize the data as volume and slices, whose color distribution is specified by a special dialog box that can pick a color in RGB or HSV format. The dialog box can also designate opacity values so that several 3-D objects can be displayed superimposed each other. Horizon picking is implemented very easily with this software thanks to the guided picking method. The picked points from a horizon will compose a set of points, mesh, and a surface, which can be viewed and analysed in three dimensions.