• Asian Journal of Atmospheric Environment
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• v.5 no.4
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• pp.237-246
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• 2011

To explore the sources of carbonaceous material in the airborne particulate matter (PM), comprehensive PM sampling was performed (3 to 14 January 2010) at a traffic hot spot site (HS), Farm Gate, Dhaka using several samplers: AirMetrics MiniVol (for $PM_{10}$ and $PM_{2.5}$) and MOUDI (for size fractionated submicron PM). Long-term PM data (April 2000 to March 2006 and April 2000 to March 2010 in two size fractions ($PM_{2.2}$ and $PM_{2.2-10}$) obtained from two air quality-monitoring stations, one at Farm Gate (HS) and another at a semi-residential (SR) area (Atomic Energy Centre, Dhaka Campus, (AECD)), respectively were also analyzed. The long-term PM trend shows that fine particulate matter concentrations have decreased over time as a result of government policy interventions even with increasing vehicles on the road. The ratio of $PM_{2.5}/PM_{10}$ showed that the average $PM_{2.5}$ mass was about 78% of the $PM_{10}$ mass. It was also found that about 63% of $PM_{2.5}$ mass is $PM_1$. The total contribution of BC to $PM_{2.5}$ is about 16% and showed a decreasing trend over the years. It was observed that $PM_1$ fractions contained the major amount of carbonaceous materials, which mainly originated from high temperature combustion process in the $PM_{2.5}$. From the IMPROVE TOR protocol carbon fraction analysis, it was observed that emissions from gasoline vehicles contributed to $PM_1$ given the high abundance of EC1 and OC2 and the contribution of diesel to $PM_1$ is minimal as indicated by the low abundance of OC1 and EC2. Source apportionment results also show that vehicular exhaust is the largest contributors to PM in Dhaka. There is also transported $PM_{2.2}$from regional sources. With the increasing economic activities and recent GDP growth, the number of vehicles and brick kilns has significantly increased in and around Dhaka. Further action will be required to further reduce PM-related air pollution in Dhaka.

• Analytical Science and Technology
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• v.14 no.5
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• pp.451-457
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• 2001

Because liquids with high molecular weight such as mineral oil have low vapor pressure at room temperature, it is generally thought to be difficult to lose them to evaporation. However, when they are dispersed into air in small droplets during application in machining processes, their surface area becomes considerably higher. To determine the potential for metalworking fluids (MWF) filter losses, MWF mist was generated and collected on polyvinyl chloride (PVC) filters in test chamber. After collected MWF was exposed to clean air during designated period (range 10~240 minutes) and the filters were desiccated, losses were evaluated. As duration of clean air passing through PVC filter increased, loss of MWF gradually increased. MWF lost after 10 minutes ranged form 12.4 % to 21.8 % of the original loading mass, on average 53.3 % of the total loss. These results indicate that significant mass of MWF collected on PVC filters can be lost at the beginning of air sampling. Loss of MWF collected on PVC filter also occurred during desiccation without active airflow. In multiple regression to identify which factors influence the loss of MWF collected on PVC filter, both duration of air passing through PVC filter and MWF age (fresh vs. used) were significant predictor (p=0.0001). Therefore, workers' exposure to MWF measured method 0500, may underestimate true concentration. Further study is needed to develop a new method to quantify the workers' exposure to airborne MWF mist accurately.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.12
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• pp.1065-1071
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• 2020

The study aims to analyze the supply chain role of supervision, discipline, work climate, and organizational learning on the performance of community services at the public works. This study took a sample of employees through purposive sampling technique at the Public Works Office and Bina Marga in a regency in East Java. Data through questionnaire was collected through a 5-point Likert scale model. The results show that the application of employee discipline affects the performance of public services, with a contribution of 39.7%, meaning that discipline and organizational learning are implementation factors that have an effect on public service performance. In stepwise regression analysis, the supervisory factor has a correlation with service performance, but it is less relevant, while the work climate is not relevant as a predictor variable to improve public service performance. The study revealed the importance of the supply chain policy of implementing good and clean governance and the enactment of the performance appraisal of the government apparatus established through Good Corporate Governance of the state apparatus. The findings provide a basis to encourage the public sector performance to smooth every step of supply chain management of every government project work, especially in the field of public services.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.1
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• pp.17-31
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• 2004

The subway play an important part in serious traffic problems. However, because subway system is a closed environment, many serious air pollution problems occurred in subway stations and injured passenger's health. Therefor, it is a necessary to identify sources and to estimate pollutant sources in order to protect passenger's health and to keep clean subway environment. The purpose of this study was to analyze a air quality in the subway stations and to apply a new receptor methodology for quantitatively estimate of PM10 sources. In this study, the size distributions of particulate matters has been measured by using Aerosizer LD (U.S.A., API, Inc.). It's real time measurement capability of time-of-flight technique offers a significant advantage of user convenience and air pollution management. Also, the mass concentrations of PM 10 has been measured by using mini-vol portable sampler (U.S.A., Airmetrics Co.). The sampling performed in Seoul subway stations during the period of February 2000 and April 2000. The number distribution data used in this study consisted of 26 raw data sets in the Jongno-sam-ga station. Correlation Analysis can be used in subway stations for source separation and identification. Then, number contribution from each source is determined by the particle number balance (PNB). The mass concentration data used in this study consisted of 31 raw data in the 8 different stations. The mass contributions of PM10 sources in the concourse by using PMF/CMB model.

• Journal of environmental and Sanitary engineering
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• v.16 no.3
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• pp.62-71
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• 2001

The present study was performed to examine the community structure of benthic macroinvertebrates in the provincial park of Mt. Daedun and its nearby region. Sampling was conducted two times in May.June and October.November, 2000. Main two areas are Mt. Anpyong (470.0m) and Mt. Daedun (877.0m) area. Total taxa of benthic macroinvertebrates were 111 species, 47 families, 15 orders, 6 classes in 4 phyla. Aquatic insects were composed of 29 species in ephemeroptera, 10 species in odonata, 7 species in plecoptera, 2 species in hemiptera, 2 species in megaloptera, 23 species trichuptera, 6 species in coleoptera and 17 species in diptera. Other non-insects were composed of 1 species in platyhelminthes, 8 species in gastropoda, 2 species in oligochaeta, 3 species in hirudinea and 1 species in crustacea. Ephemeroptera, trichoptera and plecoptera as indicators in clean water were very abundantly. Occurrence species at each surrey area was 77 species at Mt. Anpyong area and 89 species at Mt. Daedun area, respectively. Mean values of species diversity indices were 3.04 and 2.69, respectively. According to the saprobic system based on the species diversity indices of benthic macroinvertebrates, Mt. Anpyong region are determined as polysaprobic area or ${\beta}-mesosaprobic$ area and Mt. Daedun region are determined as polysaprobic area, $\beta-mesosaprobic$ area or ${\alpha}-mesosaprobic$ area.

• Journal of the Korean Wood Science and Technology
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• v.48 no.3
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• pp.283-290
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• 2020

For visual inspection-based wood identification, optical microscopy techniques typically require a relatively large sample size, and a scanning electron microscope requires a clean surface. These novel techniques experience limitations for objects with highly limited sampling capabilities such as important and registered wooden cultural properties. Synchrotron X-ray microtomography (SR-µCT) has been suggested as an effective alternative to avoid such limitations and various other imaging issues. In this study, four pieces of wood fragments from wooden members used in the Manseru pavilion of Bongjeongsa temple in Andong, Korea, wereused for identification. Three-dimensional microstructural images were reconstructed from these small wood samples using SR-µCT at SPring-8. From the analysis of the reconstructed images, the samples were identified as Zelkova serrata, Quercus sect. Cerris, and Pinus koraiensis. The images displayed sufficient spatial resolution to clearly observe the anatomical features of each species. In addition, the three-dimensional imaging allowed unlimited image processing.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.25 no.3
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• pp.67-80
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• 2020

Zinc (Zn) is known as an essential micronutrient for phytoplankton in the ocean. In surface waters, most of total dissolved Zn presents as organic complexes, and organic complexation dominates the speciation of Zn in seawater. Organic complexation reduces the bioavailable fraction of Zn, the free metal ion (Zn²⁺), which present less than 5% in surface waters. In this paper, a brief introduction on chemical speciation of dissolved Zn in seawater and analytical method for chemical speciation measurement is provided. Some representative studies were also introduced to describe the importance of chemical speciation of Zn (or other trace metals) on bioavailability and biogeochemistry in the ocean.

• Journal of environmental and Sanitary engineering
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• v.17 no.3
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• pp.115-120
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• 2002

This study was performed on a questionnaire survey of 500 people about their awareness for indoor air pollution, and measured efficiency of air cleaner which can remove the CO and air-borne particulate of ETS(Environmental Tobacco Smoke) in air clean chamber. The room-size cleaner for measuring indoor air contaminants has been applied to evaluation of two different air cleaner such as the mechanic air cleaner with hepafilter(HPA) and the electrostatic air cleaner with metal plate. The measuring experiment was carried out in a chamber by sampling the air. The results obtained were as follows; As respondents are having their 90% of daytime indoors a day, and 38% of them can feel indoor air pollutions degrees directly by their sense of smell, For the installation of indoor pollution control equipment, 34% of all respondents installed air cleaner because of the problem of economical charge and almost respondents was not satisfied the trust of ability purified indoor air pollutants. In the experimental results, it was found that more than 95% of CD and air-borne particulate of ETS were removed within 20 minutes. The reaction kinetics of removal pollutants was verified as the pseudo-first order, Finally, it appeared that the room-sire air cleaner can be applied to new technology for removing indoor air contaminants.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.114-116
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• 2005

Natural attenuation has been actively studied and often selected as final clean-up process in remediation of contaminated ground-water and soil for the last decade. Accordingly, understanding of natural processes affecting the fate and transport of contaminants in the subsurface becomes important for a success of implementation of the natural remediation strategy, Contaminant advection and diffusion processes in the unsaturated zone are naturally related to environmental changes in the atmosphere. The atmospheric pressure changes affecting the transport of contaminants in the subsurface are investigated in this study. Moisture content, trichloroethylene (TCE) concentration, temperature, and pressure variations in the subsurface were measured for the July, August, November, and December 2001 at Picatinny Arsenal, New Jersey. These data were used for a one-phase flow and one-component transport model in simulating the soil-gas flow and accordingly the TCE transport in the subsurface in accordance with the atmosphere pressure variations at the surface. The soil-gas velocities during the sampling periods varied with a magnitude of $10^{-6}\;to\;10^{-7}\;m\;s^{-1}$ at land surface. The TCE advection fluxes at land surface were several orders of magnitude smaller than the TCE diffusion fluxes. A sensitivy analysis indicated that advection fluxes were more sensitive to changes in geo-environmental conditions compared to diffusion fluxes. Of all the parameters investigated in this study, moisture content has the most significant effect on TCE advection and diffusion fluxes.

• Journal of Korean Society on Water Environment
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• v.29 no.1
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• pp.114-126
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• 2013

The purpose of this study was to develop a Korean thermality index (KTI) based on the distribution patterns of benthic macroinvertebrates according to altitude and latitude. Analyzing seasonal data (4,853 sampling units) surveyed and collected during 2007 ~ 2011 at 846 sites in South Korea, we estimated thermal valency, thermal value and indicator weight value of 208 species. Among them, 40 species in 6 orders (Decapoda 1 species, Collembola 1 species, Ephemeroptera 5 species, Plecoptera 17 species, Diptera 3 species, Trichoptera 13 species) were selected as the candidate indicator species sensitive and vulnerable to warmth along with climate change. KTI and Benthic macroinvertebrate index (BMI) were tested at three clean streams (Hangye stream, Buk stream and Bangtae stream). KTI showed significant differences according to altitude and water temperature whereas the saprobity index BMI showed little differences. This result means that KTI can be applicable to assess the impact of water temperature independently of organic pollutants.