• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2006.11a
• /
• pp.223-225
• /
• 2006

In this study, the graphite/epoxy prepregs were surface-treated using oxygen plasma, and optimal treatment time was determined measuring the contact angle en the prepreg surface. Interlaminar fracture behavior of surface-treated graphite/epoxy composite was compared with that of regular (untreated) graphite/epoxy composites. The results showed that the contact angle was a minimum when treated for 30 minutes. The interlaminar fracture toughness of surface-treated specimen was improved about 15% compared with that of regular specimen.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.49 no.2
• /
• pp.82-86
• /
• 2000

Humidity sensors using $TiO_2$ thin films were fabricated on the multi-electrode device by Sol-Gel method and their wettability, surface potential decays and humidity sensing characteristics were investigated. Contact angle of thin films was $28^{\cic}\;at\; 400^{\circ}C$ and surface potential decayed rapidly at $400^{\circ}C$. The specimen showed best humidity sensing characteristics at $400^{\circ}C$. From the results, they were confirmed that humidity sensing characteristics of thin films have connection with contact angle and surface potential decays.

• Proceedings of the KIEE Conference
• /
• 1994.07b
• /
• pp.1292-1294
• /
• 1994

With the contact angle of phase epoxy resin on the inorganic filler(glass plate) surface treated with air plasma, we have studied about the interface between epoxy resin and glass plate as simple model of a glass fiber reinforced composite materials. The contact angle on the inorganic filler surface varied with surface treatment conditions. The contact angle significantly depends on plasma treating time and environment temperature of the oven.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.1619-1624
• /
• 2004

Experimental study of separated flow over a NACA0012 airfoil is conducted at $Re=2{\times}10^5$ when periodic wakes pass over the airfoil. The wakes are periodically generated by circular cylinders upstream of the airfoil. The measurement of surface pressure and surface visualization at various angles of attack are carried out without and with passing wakes. Without passing wakes, a separation bubble at the leading edge of the suction surface is formed at an angle of attack, found from a local plateau in the streamwise pressure distribution and two distinct lines in the surface flow visualization. With passing wakes, however, the bubble disappears. Owing to passing wakes, the lift increases at high angle of attack and the angle of stall also increases.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.33 no.8
• /
• pp.559-564
• /
• 2009

The variation in the shape of water droplet moving on atomistically smooth solid surface in the presence of a constant body force is simulated using molecular dynamics simulation. We investigated how the advancing and receding contact angle of the moving water droplet changes on a solid surface having various characteristic energies. From the MD simulation results, we obtained the density profile defined as the number of water molecules at a given position. Then, assuming the water droplet periphery to be a circle, we calculated the contact angles by using a nonlinear fitting of the half-density contour line. The present simulation clearly shows the different profile of the advancing and receding contact angle for these three different interaction potential between the water droplet and the solid surface.

• Journal of Information Display
• /
• v.4 no.1
• /
• pp.1-8
• /
• 2003

Recent progress in both low pretilt and high pretilt defect free C1 surface stabilized ferroelectric liquid crystal (SSFLC) devices is reviewed. First, by numerical calculation to investigate the balance between surface azimuthal anchoring energy and bulk elastic energy within the confined chevron layer geometry of C1 and C2, it is possible to achieve a zigzag free C1 state by low azimuthal anchoring alignment with a low pretilt angle. The critical azimuthal anchoring coefficient for defect free C1 state is calculated. Its relationship with elastic constant, chevron angle as well as surface topography effect are also discussed. Second, using $5^{\circ}$ oblique SiO deposition alignment method a defect free, large memory angle, high contrast ratio and bistable C1 SSFLC display, which has potential for electronic paper applications has also been developed. The electrooptical properties and bistability of this device have been investigated. Various aspects of defect control are also discussed.

• Journal of the Korean Ceramic Society
• /
• v.47 no.5
• /
• pp.365-372
• /
• 2010

This paper was to evaluate the influence of kiln process parameter(kiln angle, kiln rotating speed) of lightweight aggregate using waste glass and bottom ash with industrial by-products on thermal conductivity, density, water absorption, fracture load and porosity by response surface analysis. In the results of surface plot and contour plot, it has verified that kiln residence time of lightweight aggregate increase as kiln angle and rotating speed decreases. For this reason, pore size and quantity tend to increase by active reaction of forming agent. It seems to be that increase in pore size and quantity have caused decreasing density, fracture load and thermal conductivity, and increasing water absorption. In conclusion, optimization of kiln process parameter on thermal conductivity, density, water absorption, fracture load and porosity by response surface analysis are kiln angle 2.4646%, kiln rotating speed 40.7089 rpm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.04a
• /
• pp.18-22
• /
• 2004

We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with rubbing alignment method on polyimide surfaces using thin plastic substrates. It was found that monodomain alignment of NLC is obtained with rubbing alignment method on polyimide surfaces using thin plastic substrates. The NLC pretilt angles generated are about $3^{\circ}$ by the rubbing alignment method on thin plastic substrates, However, the pretilt angle are at about $1.7^{\circ}$ lower on the glass substrate than on thin plastic substrate. Also, EO characteristics of the TN-LCD with a rubbed PI surface based on polymer are almost the same as that of the TN-LCD with a rubbed PI surface based on glass. However, the transmittances of the TN-LCD with a rubbed PI surface based on polymer is less than that with a rubbed PI surface based on glass.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2005.11a
• /
• pp.178-178
• /
• 2005

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.31-32
• /
• 2011