• Journal of Korea Game Society
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• v.10 no.6
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• pp.169-178
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• 2010

An effective method to render realistic metallic surface in realtime application is proposed. The proposed method perturbs the normal vectors on the metallic surface to represent small scratches. In general, bump map or normal map method is used to gnerate normal vector perturbation. However, those methods do not show plausible light scattering when applied to anisotropic reflection surface. In order to express metallic surface reflectance, MDF-based BRDF is generally employed. Therefore, the simple normal perturbation does not produce satisfactory metal rendering results. The proposed method employs not only normal perturbation but also deformation of the microfacet distribution function(MDF) that determines the reflectance properties on the surface. The MDF deformation increases the realism of metal rendering. The proposed method can be easily implemented with GPU programs, and works well in realtime environments.

• Journal of Fashion Business
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• v.15 no.3
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• pp.97-111
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• 2011

This study aims to apply 3D virtual fabric parameters - as obtained from previous research experiments - to 3D virtual clothing simulation in comparing its similarity with actual clothing as worn, with a view to verifying the objectivity and validity of the 3D virtual fabric simulation method devised by the drape image analysis method. In addition, the result is intended to be used as the basic data for new 3D virtual clothing simulation methods. As the results, 3D virtual fabric parameters designed to simulate 3D drape to be similar to actual fabrics were found to be Bending Strength, Buckling Point, Density, Particle Distance, and Shear. They were also found to be important measurements when evaluating visual similarity between drape shadow images and number of nodes. 3D virtual fabric simulation method devised by the drape image analysis method was appropriate in extracting 3D fabric parameters with the reflection of actual fabrics' physical and dynamic characteristics, in connection with 3D virtual fabric simulation. 3D virtual fabric parameters with the reflection of actual fabrics' physical and dynamic characteristics using the proposed 3D virtual fabric simulation method are accumulated and provided as a standard, this will facilitate the introduction 3D virtual fabric simulation technology.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.12
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• pp.1283-1291
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• 2003

Nonuniform transmission lines(NTLs) with the desired frequency response can be realized by synthesizing the potential from the coupled mode Zakharov-Shabat(ZS) equation in the one-dimensional inverse scattering problem. In this study, an efficient synthesis method using the ZS equations is presented for NTLs with arbitrarily specified reflection coefficients which take the restricted potential. This method lessens the line length which plague conventional design schemes using specific windows for reflection coefficients. Furthermore solving the ZS inverse transform problem is simplified by adopting the successive approach instead of the conventional iterative method. The proposed method is compared with the conventional method using specific windows by applying to design of dispersive NTL filters, and verified by two-port analysis through the chain matrix.

• Geophysics and Geophysical Exploration
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• v.16 no.1
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• pp.6-17
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• 2013

Multicomponent seismic data including both P- and PS-waves have advantages in discriminating the type of pore fluid, characterizing the lithologic attributes and producing the high resolution image. However, multicomponent seismic data recorded at the vertical and horizontal component receivers contain both P- and PS-waves which have different features, simultaneously. Therefore, the wavefield separation of P- and PS-waves as a preprocessing is inevitable in order to use the multicomponent seismic data successfully. In this study, we analyzed the previous study of the wavefield separation method suggested by Jeong and Byun in 2011, where the approximated reflection angle calculated only from one refernce depth is used in rotation transform, and showed its limitation for seismic data containing various reflected events from the multi-layered structure. In order to overcome its limitation, we suggested a new effective wavefield separation method of P- and PS-waves. In new method, we calculate the reflection angles with various reference depths and apply rotation transforms to the data with those reflection angles. Then we stack all results to obtain the final separated data. To verify our new method, we applied it to the synthetic data sets from a multi-layered model, a fault model, and the Marmousi-2 model. The results showed that the proposed method separated successfully P- and PS-reflection events from the multicomponent data from mild dipping layered model as long as the dip is not too steep.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.370.1-370
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• 2002

A method using beamforming has been developed to measure absorption coefncient of oblique incidence. MUSIC(Multiple Signal Classification) method detects the angle of incidence and reflection. And beamforming method separates the incident and reflected wave. And spatial smoothing technique is used to reduce the coherence between the incident and reflected wave. The test material were modeled as a locally reacting surface. Numerical and experiment results are performed to verify the performance of proposed method.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.5
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• pp.398-408
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• 2007

For better evaluation of material thickness by using the reflection type pulsed eddy current method, various probe models are designed and their response signals, characteristics, and sensitivities to thickness variation are investigated by a numerical analysis method. Since the sensor needs to detect magnetic fields from eddy currents induced in a test material, not from the exciter coil, two types of models that are shielded by the combination of copper and ferrite and only by ferrite are considered. By studying response signals from these shielded probe models, the peak value and the zero crossing time are selected as useful signal features for the evaluation of material thickness. Investigation of sensitivities of these two features shows that the sensitivity of peak value is more useful than that of zero crossing time and that the probe shielded only by ferrite gives much better sensitivity to thickness variation.

• The Journal of the Acoustical Society of Korea
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• v.20 no.4
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• pp.5-11
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• 2001

Acoustic characteristics of the wedge-shaped anechoic tiles, used as absorbing lining materials for an anechoic water tank, were investigated for different wedge-apex angles. The anechoic tile base has the dimensions of 400mm x 385mm x 15.5mm. In order to investigate anechoic effect, the wedge-apex angles 30° and 60° were selected by using a ray-tracing method. The reflection loss of the anechoic tiles with and without wedges were experimentally studied at normal incident sound waves in water. In this experiment, the reflection loss of wedge-shaped anechoic tiles with the optimum wedge-apex angle 30° is larger than one with the angle 60° and one without wedges. The experimental results show that the wedge-shaped anechoic tiles with the wedge-apex angle 30°, optimized by using ray-tracing method, turn out better absorbing lining materials of an anechoic water tank.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6114-6118
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• 2013

This study examined the ultrasonic pulse reflection method(UPRM) for testing each ultrasonic pulse waveform model(UPWM) based on weld defects. The sharp crack of a clear signal was generated. The echo height of the defective probes changed according to the location. In a long crack in a circle around the defective probes, the Swivel scanning echo height when using the particle was reduced drastically. The peaks in the echo were thin because the needle was pointed. The porosity defects arising from a single echo was sharp and crisp, but a number of pores of the collective reflection overlapped and ajagged echo was observed. Slag, slag inclusions, cracks, and defects at the Swivel scan of each particle using the echo shape showed difference in the degree. Cracks were revealed as sudden changes in the echo height of the slag inclusions: increase ${\rightarrow}$ decrease ${\rightarrow}$ increase ${\rightarrow}$ decrease. In addition, the location of a number of defects in the dense pore geometry, such as a typical echo sundry, revealed the shape in the slag. Poor penetration of the defect echo, revealed the cracks to have a sharp-edged, crack-like shape with an echo.

• 한국지구물리탐사학회:학술대회논문집
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• 2009.10a
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• pp.28-33
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• 2009

Methane hydrates are considered important in terms of their effect on global warming and as potential energy resources. Now, mainly the presence of a BSR and seismic velocity are used for estimation of methane hydrate concentration in the seismic reflection survey. But recent studies on seismic attenuation show that it can be used also to estimate methane hydrates concentration. In this study, we tried to estimate attenuation from 2D seismic reflection data acquired at Nankai Trough in Japan and analyzed attenuation properties in methane hydrate bearing sediments. Seismic attenuation estimated by QVO method in an offset range $125{\sim}1,575m$. We observed high attenuation in methane hydrate bearing sediments over BSR in a frequency range of 30-70Hz. Thus, this result demonstrates that seismic reflection wave within this frequency range are affected significantly by the existence of methane hydrate concentration zone.

• Journal of the Korea Society of Computer and Information
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• v.15 no.3
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• pp.11-18
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• 2010

In this study, the pulse of radial artery and oxygen saturation are detected using photoelectric plethysmograph method. Using our device designed reflection type, we can detect the reflected light by radial artery and by switching circuit, we can also separate to 625nm band signal and 940nm band signals. The separated signals are converted as a pulse data by the pulse signal processing circuit. In this study, the reflection type of oxygen saturation calculation method is applied instead of the transmission type because of the reflection type sensor is used to measure the radial artery. As a result, we can detect about 97% accuracy of the oxygen saturation compare with the conventional method. For the accurate signals, the wrist band with sensor was designed and fixed on the radial artery. As a result, this wrist band type sensor was applicable to prevent position errors from motion artifact and could increase the accuracy during the measuring.