• Macromolecular Research
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• v.8 no.3
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• pp.103-115
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• 2000

The structural changes viewed from the molecular level have been investigated for the isothermal crystallization phenomena of polyethylene (PE) and the solvent-induced crystallization phenomenon of syndiotactic polystyrene (sPS) glassy sample. The data, which were collected by the time-resolved measurements of Fourier-transform infrared spectra, Raman spectra, synchrotron-sourced small-angle X-ray scattering, wide-angle X-ray scattering, and so on, were combined together to extract the detailed structural information in these phase transition phenomena. In the case of PE, the isothermal crystallization from the melt to the orthorhombic form was found to occur via the conformationally-disordered trans chain form, followed by the formation of the lamellar stacking structure of regular orthorhombic-type crystals. In the case of sPS, the amorphous chains in the glassy sample were found to enhance the mobility through the interaction with the injected solvent molecules, which act as a trigger to cause the conformational ordering from the random coil to the regular T$_2$G$_2$-type helical form. The thus created short helical segments were found to grow into longer helices, which gathered together to form the crystallites, as revealed by the organized coupling of the infrared, Raman and X-ray scattering data.

• Journal of the Korean Applied Science and Technology
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• v.12 no.2
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• pp.157-163
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• 1995

The ultraviolet blocking agents used to skincare are largely classified ultraviolet scattering agent and ultraviolet absorbent agents. There are UVC, UVB, and UBA in ultraviolet ray(UV) showing shorter wavelength than visible light. Both visible light and UVA give rise to 1st dark-skinned phenomena. On exposure of the skin to UV, phenomena of skin variation are termed sunburn or suntan. There are chronic and acute adverse reactions in skin response to UV. The latter is caused by UVB, which has mainly effects on the skin. But lately due to destruction of ozone layer, UVA has more serious irritation on the skin than UVB. In this paper spectrometric properties of UV absorbent agents such as PABA, octyl-PABA, Urocanic acid, and 2-hydroxy-4-methoxy benzophenone in vitro have been investigate. As results, it was found that the three fomer were more suitable than the last. UV scattering measurements on the sample used inorganic pigments showed that pigments containing titanium dioxide had a better scattering effects than the inorganic pigments such as $Fe_2O_3$, $Al_2O_3$, etc.

• Journal of the Korean Vacuum Society
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• v.8 no.1
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• pp.55-62
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• 1999

Monte Carlo ion scattering program is improved with the single scattering methods where the total cross section and the mean free path are calculated as a function of atomic density during ion scattering in matter. The relations among the parameters of incident ions and substrate materials are investigated to the sputtering phenomena. The sputtering yield has been analyzed with the dependence on the incident ion species and energy, incident angle, and surface binding energy. The energy distribution of sputtered particles is discussed.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.6
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• pp.375-381
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• 2021

This paper investigated sound characteristics by the delamination of an acoustic window. In detail, acoustic scattering and transmission characteristics on the delaminated acoustic window were estimated using an experimental and numerical approach. The experiment results showed that acoustic wave could lose its amplitude and take phase delay when it propagates the delaminated acoustic window. The numerical results showed that scattering phenomena occur on the delamination surface. The scattering characteristics presented differently according to the delamination size in the acoustic window. It also showed that transmitted sound distortion due to delamination could cause a direction detection error of SONAR by changing the position of the main lobe and the magnitude of the side lobe. In conclusion, the delamination has to be managed during the manufacturing process of acoustic windows.

• The KIPS Transactions:PartA
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• v.16A no.5
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• pp.307-318
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• 2009

Modeling and rendering of atmospheric phenomena such as clouds is one of most difficult research themes in the field of computer graphics, mainly due to its complexity, huge volume, ubiquitousness, etc. In this paper, we represent a system for real-time modeling and rendering of clouds, mainly aiming at the computer games and flight simulation applications. Our implementation generates various kinds of clouds including cirrus, stratus, and cumulus, through intuitive real-timeuser interactions. Then, additional details are automatically attached to them, using our own methods based on meta-balls or hierarchical spherical particles. After processing multiple scattering and anisotropic scattering, resulting particles are rendered into billboards, to finally achieve real-time processing.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.286-287
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• 2003

Polarization-sensitive optical coherence tomography (PS-OCT) was developed to image highly scattering tissues with accounting for polarization effects in the sample. These polarization-sensitive images can provide additional information on the structure of the tissue because of a polarization state of the light is changed at its interaction with biological tissues. The scattering and birefringence are two phenomena, which change the polarization state of light passing through medium. (omitted)

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.401-406
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• 2002

A numerical model is introduced to simulate propagation, reflection, and scattering of elastic waves in solids. The model consists of mass points and linear springs, interconnected with in a lattice structure; hence, its name, the mass-spring lattice model (MSLM). The MSLM has successfully been applied to the numerical simulation and visualization of various elastic wave phenomena involved in ultrasonic nondestructive testing (NDT). This method is useful to simulate, design, or analyze actual testing. Some representative examples of numerical simulation using the MSLM are presented, and future work necessary for its further development Is addressed.

• 한국연소학회:학술대회논문집
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• 2000.05a
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• pp.16-25
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• 2000

The differential diffusion of two species in jet is considered. The direct photo images of $H_{2}/SF_{6}$ flame are taken and the non-react jets of $H_{2}/SF_{6}$ mixture are visualized with Rayleigh scattering method. The structures of Dual flame are found in the photography. As the volume fraction of $H_2$ in mixture is increased, the flame at side is long and as the volume fraction of $SF_{6}$ in mixture is increased, the flame at center is long. This phenomena are deduced from the non-react mixture using Rayleigh scattering method. Result show that the volume fraction in the mixture is important in differential diffusion.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.6
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• pp.616-623
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• 1990

This paper includes the analysis and formulation of a new model for studying scattering from wire meshes that is more efficient and simpler to apply than the previous methods. In the new method, the conjugate gradient method is employed to improve each previous iterative and the fast Fourier transform (FFT) technique is utilized. A numerical computation of mesh scattering algorithm has been carried out in the Spectral Domain. A study on the electromagnetic properties such as reflection coefficients, induced currents and aperture fields has been presented and compared with data calculated by other methods to support the validity of the algorithm.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.162-167
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• 2000

Soot formation and oxidation is closely related to the combustion phenomena inside a diesel engine. Laser-based diagnostics provide a means for improving our understanding of diesel combustion, because they have highly temporal and spatial ability. To understand the soot behavior we did preliminary study by taking flame luminosity photographs and 2-D imaging soot distribution using Laser Elastic Scattering(LIS) and Laser-Induced Incandescence(LII). From the data we found that soot concentration was high in the bowl and disappeared from the central region in the late combustion stage.