• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.867-869
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• 2008

We have investigated the effects of hydrogen plasma treatment by PECVD (Plasma Enhanced Chemical Vapor Deposition) in the back channel region, the method for reducing the off state leakage current which increases with the short channel length of a-Si:H TFTs. To improve the off current characteristics, we analyzed the hydrogen plasma treatment with various RF power and plasma treatment times of PECVD. As the result of hydrogen plasma treatment in the back channel region it was remarkably reduced the off current level of 2um channel length TFT.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.149-150
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• 2009

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2013.11a
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• pp.92-96
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• 2013

• Proceedings of the Korean Society of Medical Physics Conference
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• 1999.11a
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• pp.412-413
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• 1999

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.4
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• pp.469-476
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• 2023

Soil plasticity models for cyclic and dynamic loads are essential in non-linear numerical analysis of geotechnical structures. While a single yield surface model shows a linear behavior for cyclic loads, J₂-bounding surface plasticity model with zero elastic region can effectively simulate a nonlinearity of the ground response with the same material properties. The radius of the yield surface inside the boundary surface converged to 0 to make the elastic region disappear, and plastic hardening modulus and dilatancy define plastic strain increment. This paper presents the stress-strain incremental equation of the developed model, and derives plastic hardening modulus for the hyperbolic model. The comparative analyses of the triaxial compression test and the shallow foundation under the cyclic load can show stable numerical convergence, consistency with the theoretical solution, and hysteresis behavior. In addition, plastic hardening modulus for the modified hyperbolic function is presented, and a methodology to estimate model variables conforming 1D equivalent linear model is proposed for numerical modeling of the multi-dimensional behavior of the ground.

• Journal of Korea Multimedia Society
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• v.8 no.3
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• pp.336-344
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• 2005

In this paper, we extracted the contour of lung parenchyma on EBT images with the improved active contour model. The objects boundary in conventional active contour model can be extracted by controlling internal energy and external energy as energy minimizing form. However, there are a number of problems such as initialization and the poor convergence about concave part. Expecially, contour can not enter the concave region by discouraging characteristic about stretching and bending in internal energy. We controlled internal energy by moving local perpendicular bisector point of each control point in the contour and implemented the object boundary by minimizing energy with external energy The convergence of concave part could be efficiently implemented toward lung parenchyma region by this internal energy and both lung images for initial contour could also be detected by multi-detection method. We were sure this method could be applied detection of lung parenchyma region in medical image.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.147-147
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• 2012

Cutoff probe has been used for measuring a plasma density using the cutoff peak which is located at the plasma frequency in the low pressure plasma. However, research on analysis of low frequency region of transmission microwave frequency (TMF) spectrum does not performed even though important plasma parameters are located in the low frequency region, i.e., ion plasma frequency and collision frequency. In this research, we analyzed the low frequency region of the TMF spectrum. Experimental results reveal the effect of plasma parameters on the low frequency region on the TMF spectrum. Based on the response of TMF spectrum from changing of plasma parameters, deduction of the plasma parameters was tried. This comprehensive analysis of TMF spectrum expands applicable area of cutoff probe.

• Bulletin of the Korean Space Science Society
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• 2007.04a
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• pp.73-73
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• 2007

• Transactions of Materials Processing
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• v.27 no.5
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• pp.281-288
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• 2018

This study deals with the microstructure and tensile properties of 600 and 700 MPa-grade high-strength seismic reinforced steel bars. High-strength seismic resistant reinforced steel bars (SD 600S and SD 700S) were fabricated by TempCore process, especially the SD 700S specimen was more rapid cooled than the SD 600S specimen during the TempCore process. Although two specimens had microstructure of tempered martensite in the surface region, the SD 600S specimen had ferrite-degenerated pearlite in the center region, whereas the SD 700S specimen had bainite-ferrite-degenerated pearlite in the center region. Therefore, their hardness was highest in the surface region and revealed a tendency to decrease from the surface region to the center region because tempered martensite has higher hardness than ferrite-degenerated pearlite or bainite. The SD 700S specimen revealed higher hardness in the center region than SD 600S specimen because it contained a larger amount of bainite as well as ferrite-degenerated pearlite. On the other hand, tensile test results indicated the SD 600S and SD 700S specimens revealed continuous yielding behavior because of formation of degenerated pearlite or bainite in the center region. The SD 600S specimen had a little higher tensile-to-yield ratio because the presence of ferrite and degenerated pearlite in the center region and the lower fraction of tempered martensite enhance work hardening.

• Journal of computational fluids engineering
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• v.21 no.1
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• pp.30-35
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• 2016

In order to investigate effects of grid resolution on large-eddy simulation of flow over a heavy vehicle, large-eddy simulations over the vehicle with coarse grid and fine grid are conducted. In addition, comparison of drag coefficients with the experimental data obtained by a wind tunnel experiment is conducted. Both of the drag coefficients of coarse grid and fine grid large-eddy simulation show good agreement with the experimental data. Flow fields obtained by the coarse and the fine grid large-eddy simulation are compared in the vehicle frontal-face region, the vehicle rear wheel region, and the vehicle base region. Coarse grid large-eddy simulation shows good agreement with the fine grid large-eddy simulation in the vehicle front face region and the vehicle rear wheel region, since the flow over the present vehicle is dominated by flow separation which is geometrically pre-determined, not by the skin friction which is known to be sensitive to grid resolution.