• Journal of the Korean Geosynthetics Society
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• v.2 no.3
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• pp.19-24
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• 2003

Long-term performance of smooth and textured type HDPE geomembranes which were used to the liner and slope systems of waste landfills was examined. Artificial surface defects were added to the surface of geomembranes by scratch addition apparatus specially designed. The mechanical and frictional properties, chemical and ultra violet light resistances and oxidative induction time(OIT) of geomembranes were examined for the cases of defective/non-defective surfaces. Frictional properties of textured type geomembranes showed more excellent than those of smooth type geomembranes. Finally, it was known that the long-term performance of non-defective and textured geomembranes was better than that of defective geomembranes through chemical and UV resistance and OIT tests etc.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.23-23
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• 2003

GaN-related semiconductors are of great technological importance for the fabrication of optoelectronic devices, such as blue and ultra violet light emitting diodes (LEDs), laser diodes, and photo-detectors. One of the most important applications of GaN-based LEDs is solid-state lighting, which could replace incandescent bulbs and ultimately fluorescent lamps. For solid-state lighting applications, the achievement of high extraction efficiency in LED structures is essential. For flip-chip LEDs (FCLEDS), the formation of low resistance and high reflective p-GaN contact is crucial. So far, a wide variety of different methods have been employed to improve the ohmic properties of p-type contacts to GaN. For example, surface treatments using different chemical solutions have been successfully used to produce high-quality ohmic contacts, Metallization schemes, such as Ta/Ti contacts to p-GaN, were also investigated. For these contacts, the removal of hydrogen atoms from the Mg atoms doped n the GaN was argued to be responsible for low contact resistances.