• Journal of Korean Society for Atmospheric Environment
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• v.18 no.E3
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• pp.129-142
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• 2002

This paper provides a long-term perspective for ozone concentrations at 20 national air quality monitoring sites in Seoul from 1989 to 1998, which were managed by the Korean Ministry of Environment. Ozone episodes occurred more frequently in the east areas (Bangi, Guui, Seongsu, and Ssangmun) than in the west area (Guro and Oryu). When an ozone episode happened, hourly ozone concentrations over 80 ppb continued for an average of 4.0 hours at all sites. Annual variations in daily mean and maximum oBone concentrations showed broadly consistent upward trends at Ssangmun and Gwanaksan. Monthly mean ozone concentrations were the highest from May to June and the 99$^{th}$ and 95$^{th}$ percentile levels appeared higher during June, July, and August. The diurnal patterns of hourly mean ozone levels in urban areas showed typical photochemical formation and destruction, while the flat diurnal shape before 1996 at Gwanaksan indicated few significant photochemical reactions due to a lack of precursors of ozone. The occurrence of ozone over 80 ppb was ascribed to meteorological conditions such as high temperature, strong solar radiation, low relative humidity, and low wind speed with winds most frequently in a westerly direction.

• Journal of Korean society of Dental Hygiene
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• v.18 no.4
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• pp.433-440
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• 2018

Objectives: The purpose of this study was to investigate the pathogenicity of microorganisms by quantitative and qualitative analysis of microorganisms before and after flushing of dental unit water. Methods: This study was conducted on the supply of high-speed handpieces, ultrasonic scalers, and air-water syringes, which sterilized from 10 dental unit chairs at a dental clinic in South Gyeongsang Province. The number of bacterial communities was calculated by collection before and after flushing (2, 4, and 6 minutes). Results: The mean number of bacteria in the handpiece water before flushing was $27,208CFU/m{\ell}$; 2 minutes after flushing, $2,180CFU/m{\ell}$; 4 minutes after flushing, $900CFU/m{\ell}$; and 6 minutes after flushing, $412CFU/m{\ell}$. Conclusions: To minimize the risk of cross-infection and intra-clinic infection in dental clinics, education and water quality monitoring may be needed.

• Mass Spectrometry Letters
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• v.12 no.4
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• pp.126-130
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• 2021

The mass spectrometry (MS) provides the mass-to-charge ratios of atoms, molecules, stable/metastable complexes, and their fragments. I have taken a long journey with MS to address outstanding issues and problems by experiments and theory and gain insights into underlying principles in chemistry. By looking through the mass-to-charge ratio, I have studied thermochemical problems in silicon chemistry, the infrared multiphoton dissociation spectroscopy of organometallic intermediates, unimolecular dissociations of halotoluene radical cations, and the kinetics of association/dissociation of alkali halide triple ions with Lewis bases. Various MS platforms have been used to characterize non-covalent interactions between porphyrins and fullerenes and those between the group IIB ions and trioctylchalcogenides, and to examine the binding of the group IA, IIA and porphyrin ions to G-quadruplex DNA. Recently, I have focused on mass-balanced H/D isotope dipeptide tags for MS-based quantitative proteomics, a simple chemical modification method for MS-based lipase assay, and the kinetics and dynamics of energy-variable collision-induced dissociation of chemically modified peptides. Now, I see an important role of MS in global issues in the post-COVID era, as the society demands high standards for indoor air quality to contain the airborne-pathogen transmission as well as in-situ monitoring and tracking of carbon emissions to reduce global warming.

• Journal of Sensor Science and Technology
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• v.30 no.6
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• pp.451-455
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• 2021

Porous copper bromide (CuBr) films are highly advantageous for detecting ammonia (NH₃). The fabrication of porous CuBr films requires complex high-temperature processes or multistep processes. Herein, we report the uncomplicated preparation of porous CuBr films by a spin-coating method and the films' excellent NH₃ sensing properties. The porous films were prepared by spin-coating 100, 150, and 200 mM CuBr solutions, and then dried in a vacuum oven for 2 h. All the films showed a high NH₃ response; in particular, the film prepared using a 100 mM CuBr solution showed an extremely high response (resistance ratio = 852) to 5 ppm NH₃. The film also showed fast response and recovery times, 272 s and 10 s respectively, even at room temperature. The outstanding NH₃ sensing characteristics were explained in relation to the porosity and thickness of the prepared films. The high-performance NH₃ sensors used in this study can be used for both indoor air quality and environmental monitoring applications.

• Korean Journal of Materials Research
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• v.34 no.5
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• pp.235-241
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• 2024

Gas identification techniques using pattern recognition methods were developed from four micro-electronic gas sensors for noxious gas mixture analysis. The target gases for the air quality monitoring inside vehicles were two exhaust gases, carbon monoxide (CO) and nitrogen oxides (NO_x), and two odor gases, ammonia (NH₃) and formaldehyde (HCHO). Four MEMS gas sensors with sensing materials of Pd-SnO₂ for CO, In₂O₃ for NO_X, Ru-WO₃ for NH₃, and hybridized SnO₂-ZnO material for HCHO were fabricated. In six binary mixed gas systems with oxidizing and reducing gases, the gas sensing behaviors and the sensor responses of these methods were examined for the discrimination of gas species. The gas sensitivity data was extracted and their patterns were determined using principal component analysis (PCA) techniques. The PCA plot results showed good separation among the mixed gas systems, suggesting that the gas mixture tests for noxious gases and their mixtures could be well classified and discriminated changes.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.2
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• pp.169-182
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• 2007

To evaluate the possibly potent role of Asian Dust (AD) on the long range transport of Hg, statistical analyses were carried out using the hourly concentration data of gaseous elemental mercury (Hg) along with relevant environmental parameters. For the purpose of this study, Hg data were collected from Yang-Jae monitoring station in Seoul, Korea during Sept. 1997 to June 2002. During the study period, Hg concentrations in non-AD period ranged from $0.03\;to\;32.70\;ng\;m^{-3}$ with a mean $5.27{\pm}3.06\;ng\;m^{-3}$, while those in AD period from $1.79\;to\;32.60\;ng\;m^{-3}$ with a mean $5.20{\pm}3.06\;ng\;m^{-3}$. The air quality during AD were typically deteriorated by enhanced PM10 mass concentration (by $2{\sim}5$ times) compared to non-AD period, however comparison of the Hg concentration data indicates that they are not critically distinguished between events of AD and non-AD, except for the high minimum level of Hg during AD. The results of correlation and factor analysis also indicated somewhat complex patterns; in the case of AD events, Hg and $SO_{2}$ were assorted concurrently into a same factor. Evidence collected from this study thus suggests that long-range transport of Hg, if occurring, is unlikely to raise statistically Hg concentration levels such as seen during AD event. However, in nighttime of winter season, Hg concentrations are higher during AD (along with PM10 levels) than non-AD period. Although such observations suggest the effect of long range transport on the enhancement of Hg concentrations, more deliberate analysis may be required to track down the effect of such mechanism in relation with various factors including the air mass transport route.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.4
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• pp.346-352
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• 2022

Mountain meteorology in South Korea that is covered mountains with complex terrain is important for understanding and managing the forest disaster and forest ecosystems. In particular, recent changes in dryness and/or rainfall intensity due to climate change may cause an increase in the possibility of forest disasters. Therefore, accurate monitoring of mountain meteorology is needed for efficient forest management. Korea Forest Service (KFS) is establishing the Automatic Mountain Meteorology Observation Stations (AMOS) in the mountain regions since 2012. 464 AMOSs are observing various meteorological variables such as air temperature, relative humidity, wind speed and direction, precipitation, soil temperature, and air pressure for every minute, which is conducted the quality control (QC) to retain data reliability. QC process includes the physical limit test, step test, internal consistency test, persistence test, climate range test, and median filter test. All of AMOS observations are open to use, which can be found from the Korean Mountain Meteorology Information System (KoMIS, http://mtweather.nifos.go.kr/) of the National Institute of Forest Science and the Public Data Portal (https://public.go.kr/). AMOS observations with guaranteed quality can be used in various forest fields including the public safety, forest recreation, forest leisure activities, etc., and can contribute to the advancement of forest science and technology. In this paper, a series of processes are introduced to collect and use the AMOS dataset in the mountain region in South Korea.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.4
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• pp.387-396
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• 2003

A field study was conducted during the summer time of 2002 to determine compositions of volatile organic compounds (VOCs) emitted from vehicles and to develop source emission profiles that is applied to CMB model to estimate the source contribution of certain area. Source emission profile is widely used for the estimation of source contribution by the chemical mass balance model and have to be developed applicable for the target area of estimation. This study was aimed to develop source emission profile and estimation of source contribution of VOCs after application of the chemical mass balance (CMB) receptor model. After considering the emission inventory and other research results for the VOCs in Seoul, Korea, the sources like vehicle emission (tunnel), gas station (gasoline, diesel), solvent usage (painting operation, dry cleaning, graphic art), and gas fuels were selected for the major VOCs sources. Furthermore, ambient air samples were simultaneously collected from 09:00 to 11:00 for four days at eight different official air quality monitoring sites as receptors in Seoul during summer of 2001. Source samples were collected by canisters, and then about seventy volatile organic compounds were analyzed by gas chromatography with flame ionization detector (GC/FID). Based on both the developed source profiles and the database of the receptors, CMB model was intensively applied to estimate mass contribution of VOCs sources. Examining the source profile from the vehicle, the portion of alkanes of VOCs was highest, and then the portion of aromatics such toluene, m/p-xylene were followed. In case of gas fuel. they have their own components; the content of butane, propane, ethane was higher than any other component according to the fuel usage. The average of the source apportionment on VOCs for 8 sites showed that the major sources were vehicle emission and gas fuels. The vehicle emission source was revealed as having the highest contribution with an average of 49.6%, and followed by solvent with 21.3%, gas fuel with 16.1%, gasoline with 13.1%.

• Journal of Environmental Impact Assessment
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• v.9 no.4
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• pp.277-290
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• 2000

The purpose of this study is to identify the problems of environmental impact assessment(EIA) and to suggest new EIA technology. The problems of EIA in Korea can be summarized as follows. First, the EIA does not reflect the impact of policy, plan and program on environment. Second, the project EIA does not consider the cumulative impacts such as additive impacts, synergistic impacts, threshold/saturation impacts, induced and indirect impacts, time-crowded impacts, and space-crowded impacts. Third, the EIA techniques in Korea are not standardized. Finally, the present EIA suggests only alternatives to reduce adverse impacts. To solve above-mentioned problems, the development of new EIA technology is essential. First, the new EIA technology should be developed toward pollution prevention technology and comprehensive and integrated environmental management technology. Second, new fields of EIA for pollution prevention contain strategic environmental assessment, cumulative impacts assessment, socio-economic impact assessment, cyber EIA and EIA technology necessary after the reunification of Korean Peninsula. Third, EIA technology for integrated environmental management contains the development of integated environment assessment system and the development of packaged EIA technology. The EIA technology for integrated environmental assessment system contains (1) development of integrated impact assessment technology combining air/water quality model, GIS and remote sensing, (2) integrated impact assessment of EIA, traffic impact assessment, population impact assessment and disaster impact assessment. (3) development of integrated technology combining risk assessment and EIA (4) development of integrated technology of life cycle assessment and EIA, (5) development of integrated technology of spatial planning and EIA, (6) EIA technology for biodiversity towards sustainable development, (7) mathematical model and GIS based location decision techniques, and (8) environmental monitoring and audit. Furthermore, there are some fields which need packaged EIA technology. In case of dam development, urban or industrial complex development, tourist development, landfill or combustion facilities construction, electric power plant development, development of port, road/rail/air port, is necessary the standardized and packaged EIA technology which considers the common characteristics of the same kind of development project.

• Journal of Advanced Navigation Technology
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• v.15 no.5
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• pp.714-721
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• 2011

In this paper, developing management programs for EMI tracking can navigate the site quickly and solve EMI tracking cause and location to use materials such as analysis of air accidents, EMI site location data of 1000 RF companys, radio wave spectrum analysis and audio data. these data are databased and used comparable data. Also, EMI has been prevented by establishing continuous monitoring system through a 24-hour surveillance. Therefore we were able to provide high quality air waves in order to prevent aircraft accidents. In addition, radar control staff of Korea Airports Corporation against passenger aircraft that will prevent the worst aircraft accident have been established based to continue periodic aviation frequency protection and Portable Electronic Devices(PED) on board aircraft to prevent the culture of safety campaign.