Moon Soo Bak

During the COVID-19 pandemic, face masks have become limited in stock. Most of sterilization methods are not applicable for eliminating virus from face masks without compromising the filtration efficiency of the masks. In this study, using a human coronavirus (HCoV-229E) as a surrogate for SARS-CoV-2 contamination on KF94 face masks, we show that the virus loses its infectivity with a 4 log reduction when exposed for 10 s to 120 ppm ozone gas produced by a dielectric barrier discharge plasma gen

This paper reports on the study of repetitive nanosecond-pulsed discharge splitting of carbon dioxide (CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) for the production of CO. Gas chromatography is used to analyze the composition of the reformed gas when CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is exposed to high-voltage (15 kV) very short (10 ns) electrical discharges th

Emission measurements are carried out to study the quenching of excited electronic states of nitrogen, N2∗, in nanosecond pulsed discharges in atmospheric pressure air and nitrogen. The results reveal that ground state N2 quenches N2(C) and N2(B) at rates less than dissociative quenching by ground state O2 by a factor of 4 and 2.5, respectively. Kinetic simulations with the inferred quench rates indicate that the dissociative quenching of N2∗ by O2 is responsible for 82% of atomic oxygen product

Fast Schlieren imaging was performed to visualize the interactions between previously produced laser breakdown and a subsequent laser pulse. A pair of laser pulses was used to generate successive breakdowns in the quiescent standard air, and the interval between the pulses was varied from 50 ns to 100 μs to experimentally simulate various laser repetition rates. The incident laser energies ranged from 5 mJ to 31 mJ, and the energy absorbed by the breakdown of the second laser pulse was quantifie

Abstract Face masks are one of the currently available options for preventing the transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has caused the 2019 pandemic. However, with the increasing demand for protection, face masks are becoming limited in stock, and the concerned individuals and healthcare workers from many countries are now facing the issue of the reuse of potentially contaminated masks. Although various technologies already exist for the steriliz

This paper describes simulations of nanosecond pulse plasma formation between planer electrodes covered by dielectric barriers in air at atmospheric pressure and 340 K. The plasma formation process starts as electrons detach from negative ions of molecular oxygen that are produced from the previous discharge pulse. An ionization front is found to form close to the positively biased electrode and then strengthens and propagates towards the grounded electrode with increasing gap voltage. Charge ac

Abstract We performed non-intrusive tunable diode laser absorption spectroscopy measurements of the temperature ( T ) and water vapor concentration ( X H2O ) on a moderate or intense low-oxygen dilution combustion chamber. The combustor was operating in flameless mode by axially injecting fuel and air at high speeds through separate nozzles, thereby creating a recirculating flow of combusted gas. A pair of water vapor absorption lines near 7185.6 and 7444.36 cm −1 was used to acquire axial absor

Laser ablation has been used to study successive ignition in premixed methane/air mixtures under conditions in which the flow speed leads to flame blow-out. A range of laser pulse frequencies is experimentally mimicked by varying the time interval between two closely spaced laser pulses. Emission intensities from the laser ablation kernels are measured to qualitatively estimate laser energy coupling, and flame CH* chemiluminescence is recorded in a time-resolved manner to capture the flame evolu

The reduction of a mechanism describing plasma chemistry for dry air has been carried out for conditions of nanosecond-pulsed discharge plasmas. The discharge conditions include both diffuse glow and filamentary spark modes. A reduced set for glow discharges is found to have inelastic electron-impact reactions of N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://ww