Browsing by Author "Choi, Changsoon"
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item Enhancement of Electromagnetic Interference Shielding Effectiveness with Alignment of Spinnable Multiwalled Carbon Nanotubes(Pergamon-Elsevier Science Ltd, 2018-10-23) Lee, Duck Weon; Park, Jongwoo; Kim, Bum Joon; Kim, Hyunsoo; Choi, Changsoon; Baughman, Ray H.; Kim, Seon Jeong; Kim, Youn Tae; 0000-0001-5845-5137 (Baughman, RH); Baughman, Ray H.This research develops a unique material to attenuate electromagnetic interference (EMI) by using spinnable multiwalled carbon nanotubes (MWNTs) combined with bio-polydimethylsiloxane (PDMS) that contains BaTiO₃ (MBPBT). In particular, a plaid pattern, formed by the spinnable MWNTs, is very effective in attenuating the propagation of EM waves, which achieves over 20 dB at 8.2-12.4 GHz (X-band frequency range). This means that a filter type of the spinnable MWNTs is actively able to handle the directionality and movement of EMI propagation. In addition, the MBPBT is characterized by its strong mechanical advantage (bending radius 180 degrees).Item Harvesting Temperature Fluctuations as Electrical Energy Using Torsional and Tensile Polymer Muscles(Royal Soc Chemistry, 2015-09-28) Kim, Shi Hyeong; Lima, M©rcio D.; Kozlov, Mikhail E.; Haines, Carter S.; Spinks, Geoffrey M.; Aziz, Shazed; Choi, Changsoon; Sim, Hyeon Jun; Wang, Xuemin; Lu, Hongbing; Qian, Dong; Madden, John D. W.; Baughman, Ray H.; Kim, Seon Jeong; 0000 0003 5232 4253 (Baughman, RH); Lima, M©rcio D.; Kozlov, Mikhail E.; Wang, Xuemin; Lu, Hongbing; Qian, Dong; Baughman, Ray H.Diverse means have been deployed for harvesting electrical energy from mechanical actuation produced by low-grade waste heat, but cycle rate, energy-per-cycle, device size and weight, or cost have limited applications. We report the electromagnetic harvesting of thermal energy as electrical energy using thermally powered torsional and tensile artificial muscles made from inexpensive polymer fibers used for fishing line and sewing thread. We show that a coiled 27 μm-diameter nylon muscle fiber can be driven by 16.7 ⁰C air temperature fluctuations to spin a magnetic rotor to a peak torsional rotation speed of 70000 rpm for over 300000 heating-cooling cycles without performance degradation. By employing resonant fluctuations in air temperature of 19.6 ⁰C, an average output electrical power of 124 W per kg of muscle was realized. Using tensile actuation of polyethylene-based coiled muscles and alternating flows of hot and cold water, up to 1.4 J of electrical energy was produced per cycle. The corresponding per cycle electric energy and peak power output, per muscle weight, were 77 J kg⁻¹ and 28 W kg⁻¹, respectively.