Jungho Hwang

• Yonsei University

Nonalcoholic fatty liver disease (NAFLD) is now the leading cause of global chronic liver disease, affecting approximately 32.4% of the population in various regions and imposing healthcare and economic burdens. The gold standard for the diagnosis of NAFLD, such as liver biopsy, has numerous limitations in large-scale screening. Recent studies have...

Although the associations between a patient’s body mass index (BMI) and metabolic diseases, as well as their breath test results, have been studied, the relationship between breath hydrogen/methane levels and metabolic diseases needs to be further clarified. We aimed to investigate how the composition of exhaled breath gases relates to metabolic di...

The World Health Organization has raised concerns about the possibility of airborne transmission in enclosed and poorly ventilated areas. Therefore, rapid monitoring of airborne viruses is necessary in multi-use facilities with dense population. Accordingly, an electrostatic air sampler (250 L/min) was developed in this work to obtain indoor viral...

The COVID-19 pandemic ignited massive research into the rapid detection of bioaerosols. In particular, nanotechnology-based detection strategies are proposed as alternatives because of issues in bioaerosol enrichment and lead time for molecular diagnostics; however, the practical implementation of such techniques is still unclear due to obstacles r...

The interest in removing contagious viruses from indoor air using ventilation and filtration systems is increasing rapidly because people spend most of the day indoors. The development of an effective platform to regenerate the antiviral function of air filters during use and safe abrogation of used filters containing infectious viruses is a challe...

The assemblies of anisotropic nanomaterials have attracted considerable interest in advanced tumor therapeutics because of the extended surfaces for loading of active molecules and the extraordinary responses to external stimuli for combinatorial therapies. These nanomaterials were usually constructed through templated or seed-mediated hydrothermal...

The design of uniform graphene/noble-metal/semiconductor ternary nanocomposites without agglomeration or restacking of graphene for robust CO2 photoreduction is still challenging. This study demonstrates a strategy for fabricating reduced graphene oxide (rGO)-wrapped Ag/TiO2 nanofibers (NFs). Coaxial electrospinning with a negative electric potenti...

The unipolar saturation current limit (Isat) gives an upper limit to the corona current that can be obtained from a unipolar corona discharge. Therefore, it implies a theoretical limit to the performance of unipolar corona discharge devices. However, it has not been widely used in practice because it is difficult to deal with complex discharge conf...

There are strong demands for high biocidal and degassing performance of fibrous air filters, and the development of photocatalytic nanofiber operating under visible-light remains a challenge. We present a novel technique for the fabrication of TiO2 nanofibers (NFs) with Ag components concentrated on the fiber surface by inducing electrohydrodynamic...

Development of efficient virus aerosol monitoring and removal devices requires aerosolization of the test virus using atomizers. The number concentration and size measurements of aerosolized virus particles are required to evaluate the performance of the devices. Although diffusion dryers can remove water droplets generated using atomizers, they of...

Because of the stability of its production and cost-effectiveness, coal is expected to be a primary energy source in near future. However, SO2 and NOx emissions from the coal combustion have been considered a serious environmental issue in the last few decades; they react with water vapor and ammonia (NH3) in the atmosphere to form secondary aeroso...

Safe-by-design concepts for anticoronaviral functions are important in the production of air filters, face masks, and touch substrates because these interventions may be effective in allowing continued socioeconomic activity and alleviation of the global recession. Recent attempts to provide anticoronaviral functions have involved alternative compo...

Air purification through fiber-based filters has become a fundamental requirement for air contamination control. However, conventional filters depend on polymeric fibrous filters with adequate particulate matter removal ability but fewer degassing and biocidal effects. This study presents the photocatalytic volatile organic compound (VOC) oxidation...

We developed a reusable surface-amplified nanobiosensor for monitoring airborne viruses with a sub-PFU/mL level detection limit. Here, sandwich structures consisted of magnetic particles functionalized with antibodies, target viruses, and alkaline phosphatases (ALPs) were formed, and they were magnetically concentrated on Ni patterns near an electr...

Oil mist emitted during cooking is one of the major sources of atmospheric particulate matter in urban areas. A conventional electrostatic precipitator (ESP) is used in some large restaurants; it requires regular electrode cleaning to maintain particle collection performance. However, oil mist generated during cooking is viscous and difficult to cl...

In this study, several methods are proposed to improve the denitrification (De-NOx) performance of the selective catalytic reduction (SCR) system. To illustrate how the proposed methods can be applied, the numerical analysis for the SCR system of an industrial-scale thermal power plant is conducted. There are two important indices affecting the per...

In this study, air-blown gasification of biomass in a bubbling fluidized bed (BFB) gasifier was numerically investigated. A discrete element model coupled with computational fluid dynamics (CFD-DEM), in which gas is considered as continuum and particle is considered as discrete phase, was employed. The flow characteristics of the BFB were discussed...

Airborne virus susceptibility is an underlying cause of severe respiratory diseases, raising pandemic alerts worldwide. Following the first reports of the novel severe acute respiratory syndrome coronavirus-2 in 2019 and its rapid spread worldwide and the outbreak of a new highly variable strain of influenza A virus (H1N1) in 2009, developing quick...

Capturing virus aerosols in a small volume of liquid is essential when monitoring airborne viruses. As such, aerosol-to-hydrosol enrichment is required to produce a detectable viral sample for real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) assays. To meet this requirement, the efficient and non-destructive collecti...

To increase the hydrogen (H2) concentration in bio‐syngas containing carbon dioxide(CO2), water‐gas shift reaction (WGSR) is widely used. In this study, the effects of CO2 concentration on the WGSR and unwanted side reactions were investigated by varying the operating parameters, such as the steam/carbon monoxide (CO) ratio, reaction temperature, a...

Electrostatic separation of particles from air onto a liquid surface has attracted increasing attention for various applications such as wet electrostatic precipitators and bioaerosol samplers. In this study, the electrostatic separation of particles onto the liquid surface is numerically modeled in a simplified manner. The simulated separation eff...

Rapid monitoring of biological particulate matter (Bio-PM, bioaerosols) requires an enrichment technique for concentrating the Bio-PM dispersed in air into a small volume of liquid. In this study, an electrostatic air sampler is employed to capture aerosolized test bacteria in a carrier liquid (aerosol-to-hydrosol (ATH) enrichment). Simultaneously,...

An electret filter composed of electrically charged fibers exhibits high efficiency, while maintaining a low pressure drop. Therefore, the electret filter is used in heating, ventilation, and air-conditioning (HVAC) systems. However, charges on the fiber can be shielded or neutralized by collected dust particles, degrading the collection efficiency...

Gaseous potassium chloride (KCl) that constitutes a relatively large portion of the combustion gas of municipal solid waste can condense on the surface of boiler heat exchanger tubes, causing severe corrosion attacks. To reduce the chlorine-induced high-temperature corrosion, sulfate-based additives have been used. In this study, a two-step numeric...

Recently, various studies have reported the prevention and treatment of respiratory infection outbreaks caused by lethal viruses. Consequently, a variety of air filters coated with antimicrobial agents have been developed to capture and inactivate virus particles in continuous airflow conditions. However, since aerosolized infectious viral-testing...

Because of enhanced efficacy and lower side effects, cancer immunotherapies have recently been extensively investigated in clinical trials to overcome the limitations of conventional cancer monotherapies. Although engineering attempts have been made to build nanosystems even including stimulus nanomaterials for the efficient delivery of antigens, a...

Cyclone separators are key components of circulating fluidized bed (CFB) boilers. The factors that can affect the cyclone performance include body diameter, total height of the cyclone, and diameter and length of the vortex finder (VF). In this study, the effect of the VF length on the cyclone performance in a 340‐MWe CFB boiler operated by Korea S...

We present a portable, inexpensive, and accurate microelectromechanical-system-based (MEMS-based) condensation particle counter (CPC) for sensitive and precise monitoring of airborne ultrafine particles (UFPs) at a point of interest. A MEMS-based CPC consists of two main parts: a MEMS-based condensation chip that grows UFPs to micro-sized droplets...

Human exposure to airborne pathogens is a major cause of health concerns; therefore, it is imperative to monitor, sample, and detect airborne bio-particles. Among various bio-aerosol sampling methods, electrostatic precipitation (EP) is an efficient technique for capturing bio-aerosols as hydrosols due to a lower pressure drop and less damage to se...

In this study, the dense flow characteristics in a Lapple cyclone were investigated using numerical simulations. At a high solid volume fraction, four-way coupling must be applied to account for solid volume fraction in Navier-Stokes equations and particle-particle collisions, which are not considered in one- and two-way couplings approaches. A fou...

In conventional coal-fired power plants, selective catalytic reduction (SCR) is used for NOx removal and wet scrubbing is used for SO2 removal. Because of the high operational cost of SCR, researchers have applied wet scrubbing for De-NOX, without SCR. Herein, NO was injected in a lab-scale reactor and oxidized to NO2 by reacting with ozone. Subseq...

Control of the particle size distribution of fabricated alumina nanoparticles from general alumina powder with a large geometric standard deviation (GSD) was studied. A thermophoretic separator was used to control the GSD of the nanoparticles, and unevaporated and primary particles were separated to yield a small GSD. The fabricated nanoparticles w...

Safe-by-design principles, such as optimum balances of material function and safety have received much recent attention. On-demand production is also receiving great interest in the realization of nanotechnologies that meet unpredictable demands of reconfiguration and modification to maximize the efficacy of materials processing. Antimicrobial nano...

To monitor airborne nanoparticles at a particular point of interest sensitively and accurately, we developed a compact and inexpensive but highly-precise nanoparticle detection system. The proposed system, based on nucleation light-scattering, consists of two components: a microelectromechanical system (MEMS)-based particle growth chip that grows n...

We present a microelectromechanical system (MEMS)-based condensation particle counter (CPC) for sensitive and precise monitoring of airborne ultrafine particles (UFPs) at a point of interest that is portable, inexpensive, and accurate. The proposed system consists of two main parts: a MEMS-based condensation chip that grows UFPs to micro-sized drop...

Simultaneous improvement in detection speed and reliability is critical for bioaerosol monitoring. Recent rapid detection strategies exhibit difficulties with misinterpretation due to signal interference from co-existing nonbiological particles, whereas biomolecular and bioluminescent approaches require long process times (>several tens of minutes)...

The nanoparticle production process in a transferred arc plasma system was studied. The plasma temperature, particle heating time, and particle residence time in plasma were calculated using heat and mass balance with a lumped capacitance method. We analyzed the nanoparticle production characteristics based on different operating conditions by comp...

A MEMS-based particle detection system which includes a particle processing chip and electronic circuits was developed for low-cost and ubiquitous monitoring of airborne ultrafine particles. The detection system consists of particle classification, charging, precipitation, and sensing sections. Particles with different sizes enter the ultrafine par...

In recent years, there has been a growing interest in the ultrafine particle (PM2.5), because public health has been threatened. Gas-phase sulfur oxides discharged from the coal-fired power plants are designated as the main source of ultrafine dust. Therefore, coal-fired power plants are operating flue gas desulfurization facilities to remove gas-p...

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...

Staged combustion induces the reduction of NO to generate N2 through the formation of a fuel-rich zone upstream of the flue gas and utilizes the unburned gas by supplying sufficient air for combustion downstream of the flue gas. Since power generation schedules are very constrained and only specific and limited tests can be planned and executed, th...

Electro-aerodynamic particle jet printing is a method to fabricate transparent electrodes, which have been used in applications such as solar cells, display screens, and touchscreen panels. The desired TE sheet resistance and transmittance are realized by trial and error through repeated printing experiments with different parameters such as nozzle...

The competition between the H2O and CO2 for the active sites during gasification remains a controversial issue in the literature. In this study, the competition between the H2O and CO2 for the active sites during gasification of coal, biomass, and a mixture of coal and biomass using the Langmuir–Hinshelwood (L–H) kinetic parameters obtained in our...

Although the amount of allergens and toxins being originated from viable bacteria is higher than that from dead bacteria, monitoring concentrations of dead bacteria as well as live bacteria is an important issue related to human health. The ultraviolet aerodynamic particle sizer (UVAPS) is an instrument to measure the size distribution of only viab...

Co-gasified coal and biomass offers several advantages including reduction of CO2 emissions and decreased fossil fuel dependency. Due to the slow reaction rate, char gasification dominates solid fuel conversion. Hence, understanding the mechanisms of char gasification is essential for the design, optimization, and simulation of the gasifier. Severa...

For rapid and effective detection of airborne microorganisms, it is preferable to remove dust particles during the air sampling process because they can reduce the detection accuracy of measurements. In this study, a methodology of real-time separation of aerosolized Staphylococcus epidermidis (S. epidermidis) and polystyrene latex (PSL) particles...

Co-utilization of coal and biomass in a power plant can reduce the overall CO2 emission by partly displacing fossil-fuel combustion with near-carbon-neutral combustion of biomass. Computational fluid dynamics (CFD) modeling of co-gasification is conducted using a validated gasification model to examine the effect of biomass amount on the co-gasific...

The rapid increase in the concentration of pathogenic airborne bacteria is a serious issue because of their infectivity. Due to the abundance of these infectious pathogens in the environment, researchers have developed devices to detect airborne pathogens using microfluidic technologies. Such devices represent a significant improvement over convent...

Hot gas cleaning of producer gas generated from a gasification process has many advantages in terms of thermal efficiency, gas-quality improvement, compact gas-cleaning devices, and economic feasibility. In this study, the characteristics of molten tin as a working fluid for hot gas cleaning were examined. To evaluate the hot gas cleaning performan...

This study investigates particle transport hydrodynamics and coal combustion in an industrial-scale circulating fluidized bed (CFB) combustor using the dense discrete phase model (DDPM). DDPM is an extension of the discrete phase model (DPM); however, unlike the standard formulation of DPM, DDPM considers the solid volume fraction when solving the...

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...

Electrostatic precipitators (ESPs) have been widely used to control particulate pollutants, which adversely affect human health. In this study, a computational fluid-dynamic model for turbulent flow, particle trajectory, and particle charging in ESPs is presented using a pre-developed corona discharge model (Kim et al., 2010), wherein electric fiel...

Several efforts have been made for the prediction of jet diameter in electrohydrodynamic jet printing; however, not much attention has been paid to the jet length, which is the distance from the cone apex to the location where the jet is unstable and is broken into atomized droplets. In this study, we measured both the cone length and the jet lengt...

This study developed a model to investigate the transient 3D numerical simulation of air and sand particle hydrodynamics along with coal combustion in an industrial scale CFB furnace. This model used the Dense Discrete Phase Model (DDPM) to model the interactions of sand (inert bed material) and coal particles with the gas phase. DDPM is an Euleria...