Joong-Han Yoon

Design of Multiple U-Shaped Slot Microstrip Patch Antenna in 5 GHz Band WLAN

In this study, a multiple U-shaped slot microstrip patch antenna for application to the 5 GHz band is designed and fabricated. To obtain sufficient bandwidth in the operating band, foam is inserted between the substrate and ground plane, the type of form is styrofoam, the coaxial probe source is used, and the position of the probe shift is adjusted from the center to the left. The measured result (5.02-5.955 GHz) of the fabricated antenna satisfies the conditions of VSWR < 2.0 in 5 GHz band (5.15-5.35 GHz, 5.47-5.725 GHz, 5.725-5.825 GHz), gain of 3.88-9.28 dBi, and broad radiation pattern.

Rheological Study on Biodegradable Poly(3-Hydroxybutyrate) and Its Copolymer

Some aspects of rheological properties of microbial biodegradable copolymers containing 3-hydroxybutyrate and 3-hydroxyvalerate have been studied in this work, using both rotational rheometer with parallel plate geometry and capillary rheometer. Dynamic viscoelasticity as functions of time and temperature was also measured by Rheovibron.