Hwajin Kim

Abstract. Non-refractory submicrometer particulate matter (NR-PM1) was measured in the Seoul Metropolitan Area (SMA), Korea, using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) from 14 April to 15 June 2016, as a part of the Korea-US Air Quality Study (KORUS-AQ) campaign. This was the first highly time-resolved, real-time measurement study of springtime aerosol in SMA and the results reveal valuable insights into the sources and atmospheric processes that cont

Abstract. The San Joaquin Valley (SJV) in California experiences persistent air-quality problems associated with elevated particulate matter (PM) concentrations due to anthropogenic emissions, topography, and meteorological conditions. Thus it is important to unravel the various sources and processes that affect the physicochemical properties of PM in order to better inform pollution abatement strategies and improve parameterizations in air-quality models. During January and February 2013, a gro

Abstract. Thermodenuding particles can provide insights into aerosol composition and may be a way to create particles in laboratory chambers that better mimic the atmosphere. The relative volatility of secondary organic aerosol (SOA) was investigated by evaporating organics from the particles using a thermodenuder (TD) at temperatures between ∼60 and 100 °C. Volatility was influenced by the parent hydrocarbon, oxidation chemistry and relative humidity (RH). For SOA generated from ozonolysis, lim

Abstract. Highly time-resolved chemical characterization of nonrefractory submicrometer particulate matter (NR-PM1) was conducted in Seoul, the capital and largest metropolis of Korea, using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The measurements were performed during winter, when elevated particulate matter (PM) pollution events are often observed. This is the first time that detailed real-time aerosol measurement results have been reported from Seoul

This study discusses an analysis of combined airborne and ground observations of particulate nitrate (NO₃ ^- _(p)) concentrations made during the wintertime DISCOVER-AQ study at one of the most polluted cities in the United States, Fresno, CA in the San Joaquin Valley (SJV) and focuses on development of understanding of the various processes that impact surface nitrate concentrations during pollution events. The results provide an explicit case-study illustration o

Abstract. Nitrogen oxides (NOx) have fallen steadily across the US over the last 15 years. At the same time, NOx concentrations decrease on weekends relative to weekdays, largely without co-occurring changes in other gas-phase emissions, due to patterns of diesel truck activities. These trends taken together provide two independent constraints on the role of NOx in the nonlinear chemistry of atmospheric oxidation. In this context, we interpret interannual trends in wintertime ammonium nitrate (N

The refractive index is the fundamental property controlling aerosol optical properties. Secondary organic aerosol (SOA) real refractive indices ( m r ) were derived from polar nephelometer measurements using parallel and perpendicular polarized 670 nm light, using a genetic algorithm method with Mie‐Lorenz scattering theory and measured particle size distributions. The absolute error associated with the m r retrieval is ±0.03, and the instrument has sufficient sensitivity to achieve reliable re

Abstract This paper is concerned with simulation-based approaches in the shipbuilding industry such as digital shipbuilding, simulation-based design (SBD), and a virtual shipyard. A simulation-based shipbuilding model based on the function model of ship design and the process model of ship manufacturing is suggested. For application and implementation of the proposed model, the process model for block erection processes is designed using IDEF0 and UML methodologies. In addition, an application i

Abstract. Severe haze episodes have occurred frequently in the Seoul metropolitan area (SMA) and throughout East Asian countries, especially during winter and early spring. Although notable progress has been attained in understanding these issues, the causes of severe haze formation have not yet been fully investigated. SMA haze is especially difficult to understand, because the area is impacted by both local emissions from anthropogenic and biogenic activities and emissions transported from upw

The refractive index is an important property affecting aerosol optical properties, which in turn help determine the aerosol direct effect and satellite retrieval results. Here, we investigate the real refractive indices (m(r)) of secondary organic aerosols (SOA) generated from the photooxidation of limonene and α-pinene with different HC/NO(x) ratios. Refractive indices were obtained from polar nephelometer data using parallel and perpendicular polarized 532 nm light combined with measured size

Abstract. High levels of fine particulate matter (PM2.5) pollution in East Asia often exceed local air quality standards. Observations from the Korea–United States Air Quality (KORUS-AQ) field campaign in May and June 2016 showed that development of extreme pollution (haze) occurred through a combination of long-range transport and favorable meteorological conditions that enhanced local production of PM2.5. Atmospheric models often have difficulty simulating PM2.5 chemical composition during haz