We report highly effective hydrogen gas detection based on the metal–insulator transition (MIT) by the electrothermally induced Pd-nanoparticles-decorated vanadium oxide (VO2) nanowire prepared by the efficient and size-controllable growth method originating from V2O5 thin film driven by supercooled liquid nanodroplets. By irradiating a well-defined electron beam into the nanowires, we could significantly increase the conductivity up to four times with only a modest change in the semiconductor-to-metal transition temperature (<2 °C). When exposed to trace amounts of hydrogen gas in a single nanowire configuration, the enhanced conductivity gave rise to about a two times as fast transition to metallic phase even near room temperature (∼35 °C), by reaching much faster (∼3×) a critical current density at which the self-heating initiates. Consequently, we achieved the greatly shorter response time as well as lower operating temperature and voltage for the detection of hydrogen gas in a single VO2 nanowire device, which can be attributed to the self-heating effect accelerated by the increase in the conductivity. The single nanowire sensor also shows the capability of detecting selectively hydrogen of different three gases (O2, CO, and ethylene).

We review the history of space missions in Korea focusing on the field of astronomy and astrophysics. For each mission, scientific motivation and achievement are reviewed together with some technical details of the program, including mission schedule. This review includes ongoing and currently approved missions, as well as some planned ones. Within the admitted limitations of the authors' perspectives, some comments on the future direction of the space program for astronomy and astrophysics in Korea are made at the end of this review.

Testing and Performance of UFFO Burst Alert & Trigger Telescope JakubŘípa Figure 1: Left: A photo shows the assembled UFFO-p with its two scientific instruments: UBAT and SMT. Right: A schematic view of UBAT is drawn. It consists of a coded mask, hopper, detector and readout electronics.