Jeong-kuk Shon

Characterization of a thin, uniform coating on P2-type Na2/3Fe1/2Mn1/2O2 cathode material for sodium-ion batteries

A thin, uniform carbon coating on Na2/3Fe1/2Mn1/2O2 (NFMO) using 2,3-dihydroxynaphthalene (DN) was prepared. Pristine and DN-coated samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). An amorphous nanolayer coating of carbon is obtained on the surface of the layered pristine material. The 0.2 wt% DN-coated NFMO exhibits excellent electrochemical performance. An initial discharge capacity of 178 mA h g−1 was obtained at a C-rate of 0.1 C; this capacity is 20% higher than bare NFMO. Capacity retention (77.8% at the 50th cycle) is also maintained comparable to bare NFMO (77.7% at the 50th cycle). The thin and uniform carbon layer leads to improvement of charging and discharging kinetics and protects against direct contact between cathode and electrolyte.

Reduction of Noise in Strapped Magnetron by Electric Priming using Anode Shape Modification

Noise reduction in a 2.45 GHz strapped magnetron oscillator is experimentally demonstrated by electric priming using anode shape modification. The sideband noise are reduced by about 15 dB at the nominal operating current and 28 dB at the start-oscillation current due to electron prebunching into the pi-mode resulted from the modulation of the drift velocity of the electron using the azimuthally periodic electric field. In this experiment, a 4.3kV and 330mA half-wave rectified input power is employed

Nonstationary behavior in 10-vane strapped magnetron oscillator

In this paper, the study on the noise is investigated from the nonstationary behavior. The transition from the stationary state to the nonstationary state of the 10-vane strapped magnetron oscillator is observed as the normalized cathode current is increased using the three-dimensional particle-in-cell code, MAGIC3D.

Three-dimensional simulation of 10-vane strapped magnetron

This paper deals about three dimensional simulation of 10-vane strapped magnetron. A 10-vane strapped magnetron operating at 2.465 GHz for the microwave oven is modeled using three-dimensional particle-in-cell simulation code, called as MAGIC3D. The intention of this study to understand the origin of the leaked radiation from the microwave oven using 3D simulation.