Junho Hyun

• PhD Student at Yonsei University

Increasing public concern regarding air quality has led to the development of efficient aerosol-monitoring techniques. Among the various aerosol measurement instruments based on electrical methods, in this study, an electrical cascade impactor (ECI) was designed and fabricated in our laboratory and was used to measure the real-time size distributio...

Airborne particulate matter is an important factor in the quality of an indoor environment. In this study, a miniaturized particle sensor was developed to detect submicron-sized aerosols based on number counting. This particle number (PN) sensor was designed and fabricated for real-time measurement of total aerosol number concentration and geometri...

The effect of corona discharge-generated air ions on the filtration of aerosolized bacteriophage MS2 was studied. A carbon-fiber ionizer was installed upstream of a medium-efficiency air filter to generate air ions, which were used to charge the virus aerosols and increase their filtration efficiency. After the virus aerosols were captured by the f...

To assess indoor bioaerosols, a virtual impactor having 1 µm cutoff diameter was designed, fabricated, and evaluated with computational fluid dynamics simulation and also with laboratory test using polystyrene latex particles. Two other cutoff diameters of 635 nm and 1.5 µm were obtained by changing the inlet flow rate and the ratio of minor channe...

A serial method is described for estimating the particle effective density and dynamic shape factor of particles, i.e., diesel exhaust particles (DEPs). For this purpose, we designed a single stage low-pressure impactor with a cutoff diameter of 130 nm. The collection efficiency curve of the impactor was obtained using mobility-classified sodium ch...

Since airborne bacteria have been known to aggravate indoor air quality, studies on reducing bacteria particles increase recently. In this study, a chamber(0.8m x 0.8m x 1.56m) system was built in order to simulate real conditions for reducing airborne bacteria, and evaluated by a simple aerosol reduction test. A method utilizing CFD(Computational...

While heating, ventilating, and air-conditioning (HVAC) systems can provide healthy and comfortable indoor environments, virtually any part of an HVAC system can support active microbial growth if sufficient nutrients are present. In this study, we introduced a methodology to enhance the one-pass antibacterial performance of air ions against aeroso...

We theoretically investigated the momentum transfer and energy conversion process of ion-neutral and ensuing neutral-neutral collisions in the ion drift region of electrohydrodynamic flow. Our results are presented in explicit equations with physical interpretations of the phenomena. The unit conversion process was estimated to sustain for 1.0 nano...

Characterization of particulate matter (PM) emitted from diesel vehicle exhaust requires a real-time measurement sensor to record particle concentrations under transient tests. Recently, a micro-machined unipolar charger (MUC) based on a micro-electromechanical system (MEMS) was introduced and evaluated to test aerosol particles on a laboratory sca...