Annie Hyojeong Jeong, Violin

Sonata for Violin and Piano No. 2 in A major, Op. 100 / Johannes Brahms; Havanaise, Op. 83 / Camille Saint-Saëns; Sonata for Violin and Piano No. 3 in C minor, Op. 45 / Edvard Grie

Foreword by guest editors for the Special Issue on the 2013 ICUFN Conferencs

Jeong, S.; Rodrigues, JJPC.; Cano Escribá, JC. (2014). Foreword by guest editors for the Special Issue on the 2013 ICUFN Conferencs. Wireless Personal Communications. 78(4):1827-1831. doi:10.1007/s11277-014-2046-yS1827183178

4.5-/4.9-GHz-Band Selective High-Efficiency GaN HEMT Power Amplifier by Characteristic Impedance Switching

A 4.5-/4.9-GHz band-selective GaN HEMT high-efficiency power amplifier has been designed and evaluated for next-generation wireless communication systems. An optimum termination impedance for each high-efficiency operation band was changed by using PIN diodes inserted into a harmonic treatment circuit at the output side. In order to minimize the influence of the insertion loss of the PIN diodes, an additional line is arranged in parallel with the open-ended stub used for second harmonic treatment, and the line and stub are connected with the PIN diodes to change the effective characteristic impedance. The fabricated GaN HEMT amplifier achieved a maximum power-added efficiency of 57% and 66% and a maximum drain efficiency of 62% and 70% at 4.6 and 5.0GHz, respectively, with a saturated output power of 38dBm, for each switched condition

A master\u27s recital in piano

On March 14, 2014, Min Jeong Kim presented a recital in completion of her Master’s degree in Piano Performance. The recital was held at 6 p.m. in Davis Hall at the University of Northern Iowa School of Music. Pieces on the program included: Prelude and Fugue in C minor, BWV 871 by Johann Sebastian Bach, Klavierstücke, Op. 118 by Johannes Brahms, Rain Tree Sketch II by Toru Takemitsu, and Sonata in E-flat Major, Op. 81a by Ludwig van Beethoven

Production and Characterization of Zeolite Membrane

The use of bioethanol as an alternative fuel with a purity of more than 99.5% wt has prompted research on bioethanol purification. One of the promising methods used for bioethanol purification is pervaporation membrane. This research is aimed to prepare and characterize zeolite membranes for pervaporation membrane. The membrane preparation consisted of two stages, namely support preparation and zeolite deposition on the support. In support preparation, α alumina and kaolin with spesific composition (50:30; 40:40; 50:30) was mixed with additives and water. After pugging and aging process, the mixture became paste and extruded into tubular shape. The tube was then calcined at temperature of 1250 °C for 3 hours. After that, zeolite 4A is deposited on the tubes using clear solution made of 10 %wt zeolite and 90 %wt water and heated at temperature of 80 °C for 3 hours. Furthermore, the resulting zeolite membranes was washed with deionized water for 5 minutes and dried in oven at temperature of 100 °C for 24 hours. Characterization of zeolite membranes included mechanical strength test, XRD, and SEM. In the mechanical strength test, the membrane sample with alumina:kaolin = 50:30 (#membrane A#) has the highest mechanical strength of 46.65 N/mm2. Result of XRD analysis for the membran A indicated that mullite and corundum phases were formed, which mullite phase was more dominant. Meanwhile the result of SEM analysis shows that zeolite crystals have been formed and covered the pores support, but the deposition of zeolite has not been optimal yet. The performance examination for bioethanol purification showed that the membrane could increase the purty of bioethanol from 95% to 98% wt