• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.11 s.242
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• pp.1488-1493
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• 2005

In this study, fatigue tests to obtain S-N curves and FE analyses to obtain structural stress concentration factors were conducted for the two types of cruciform fillet welded joints, that is, load-carrying and non load-carrying types. Then we changed the obtained S-N curve of load carrying joint to that based on hot spot stress. As a result, the S-N curve of load carrying joint based on hot-spot stress was almost exactly coincided with that of non load-carrying joint based on nominal stress. So we have conducted that the fatigue strength of a welded joint with different geometry from the non stress distribution along the expected crack path.

• Journal of Environmental Health Sciences
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• v.35 no.2
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• pp.86-94
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• 2009

This study analyzed the concentration of the lead in blood (n=774) from May, 2007 to Oct 2007. The subject was residents in G, Y, H industrial area, Jeollanam-do, in which exposure to the lead is expected due to the adjacency of the industrial complex. As to the lead concentration in the blood of the residents in the whole exposed region and the comparing region, $2.81{\mu}g/dl$ in the exposed region group, and $2.86{\mu}g/dl$ in the comparing region group Respectively, which indicates that the concentration of the comparing group was higher than that of the exposed group. The geometric mean concentration of lead in blood was $3.26{\mu}g/dl$ as to men, and $2.46{\mu}g/dl$ as to women, which indicates that the concentration of men is higher than that of women (p<0.01). The lead concentration for each age group increased in proportion to age except those under 10 for some substances (p<0.01). As to geometric mean concentration in blood according to the smoking history of the subject, the concentration of the smoking group and the non-smoking group was $3.57{\mu}g/dl$ and $2.66{\mu}g/dl$ respectively, which indicates the former is higher than the latter (p<0.01). To clarify the factors affecting the heavy metal concentration in blood among the subjects, the multiple regression analysis was conducted. As a result, it turned out that as to lead content in blood, gender, age, smoking all affect the lead concentration of the subjects ($R^2$=23.3%).

• 한국공간정보시스템학회:학술대회논문집
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• 2007.06a
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• pp.246-251
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• 2007

The purpose of this study is to develop a grid based model for calculating the critical nonpoint source (NPS) pollution load (BOD, TN, TP) in Nak-dong area in South Korea. In the last two decades, NPS pollution has become a topic for research that resulted in the development of numerous modeling techniques. Watershed researchers need to be able to emphasis on the characterization of water quality, including NPS pollution loads estimates. Geographic Information System (GIS) has been designed for the assessment of NPS pollution in a watershed. It uses different data such as DEM, precipitation, stream network, discharge, and land use data sets and utilizes a grid representation of a watershed for the approximation of average annual pollution loads and concentrations. The difficulty in traditional NPS modeling is the problem of identifying sources and quantifying the loads. This research is intended to investigate the correlation of NPS pollution concentrations with land uses in a watershed by calculating Expected Mean Concentrations (EMC). This work was accomplished using a grid based modelling technique that encompasses three stages. The first step includes estimating runoff grid by means of the precipitation grid and runoff coefficient. The second step is deriving the gird based model for calculating NPS pollution loads. The last step is validating the gird based model with traditional pollution loads calculation by applying statistical t-test method. The results on real data, illustrate the merits of the grid based modelling approach. Therefore, this model investigates a method of estimating and simulating point loads along with the spatially distributed NPS pollution loads. The pollutant concentration from local runoff is supposed to be directly related to land use in the region and is not considered to vary from event to event or within areas of similar land uses. By consideration of this point, it is anticipated that a single mean estimated pollutant concentration is assigned to all land uses rather than taking into account unique concentrations for different soil types, crops, and so on.

• YAKHAK HOEJI
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• v.43 no.6
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• pp.834-842
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• 1999

The metabolism and pharmacokinetics of M-l, which is metabolite of pentoxifylline, have been studied in human liver microsomes. Biphasic kinetics was observed from the Eadie-Hofstee plot for the formation of both metabolites of M-l. For the kinetics of pentoxifylline, mean values of $V_{max1}{\;}and{\;}V_{max2}$ were 1,648 and 5,622 nmol/min/mg protein, and the estimated values of $K_{ml}{\;}and{\;}K_{m2}$ were 0.180 and 4.829 mM, respectively. For M-3, mean values of $V_{max1}{\;}and{\;}V_{max2}$ were 0.062 and 0.491 nmol/min/mg protein, and estimated values of $K_{ml}{\;}and{\;}K_{m2}$ were 0.025 and 1.216 mM. The formations of pentoxifylline and M-3 from M-1 were indentified by using several selective inhibitors of cytochrome P450 isoformes at 0.05-5 mM concentration of M-1 in human liver microsomes. For the analysis of low (0.05 mM) concentration of M-1, where the affinity was expected as low, indicated that CYPlA2 and CYP3A4 were major P450 isoforms responsible for pentoxifylline and M-3 formation. CYP3A4 and CYP2A6 appeared to be P450 isoforms responsible for M-3 formation at high (5 mM) concentration of M-1.

• BMB Reports
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• v.34 no.6
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• pp.551-558
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• 2001

We extended the measurable time scale of DNA dynamics to submicrosecond using a long-lifetime metal-ligand complex, $[Ru(phen)_2(dppz)]^{2+}$ (phen=1,10-phenanthroline, dppz=dipyrido[3,2-a:2',3'-c]phenazine) (RuPD), which displays a mean lifetime near 350 ns. We partially characterized the fluorescence resonance energy transfer (FRET) in calf thymus DNA from RuPD to nile blue (NB) using frequency-domain fluorometry with a high-intensity, blue light-emitting diode (LED) as the modulated light source. There was a significant overlap of the emission spectrum of the donor RuPD with the absorption spectrum of the acceptor NB. The F$\ddot{o}$rster distance ($R_0$) that was calculated from the spectral overlap was $33.4\;{\AA}$. We observed dramatic decreases in the steady-state fluorescence intensities of RuPD when the NB concentration was increased. The intensity decays of RuPD were matched the closest by a triple exponential decay. The mean decay time of RuPD in the absence of the acceptor NB was 350.7 ns. In a concentration-dependent manner, RuPD showed rapid intensity decay times upon adding NB. The mean decay time decreased to 184.6 ns at $100\;{\mu}M$ NB. The FRET efficiency values that are calculated from the mean decay times increased from 0.107 at $20\;{\mu}M$ NB to 0.474 at $100\;{\mu}M$ NB concentration. The use of FRET with a long-lifetime metal-ligand complex donor is expected to offer the opportunity to increase the information about the structure and dynamics of nucleic acids.

• Journal of Environmental Health Sciences
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• v.49 no.5
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• pp.275-288
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• 2023

Background: When basic local governments want to improve their air quality management policies, they need fundamental evidence, such as the effectiveness of current policies or scenario results. Objectives: The purpose of this study is to lay the groundwork for a process to calculate air pollutant reduction from basic local government air quality policies and provide numerical estimates of PM_2.5 concentrations following improved policies. Methods: We calculated the amount of air pollutant reduction that can be expected in the research region based on the Gyeonggi-do Air Environment Management Implementation Plan issued in 2021 and guidelines from the Korean Ministry of Environment. The PM_2.5 concentration variations were numerically simulated using the CMAQ (photochemical air quality model). Results: The research regions selected were Suwon, Ansan, Yongin, Pyeongtaek, and Hwaseong in consideration of population, air pollutant emissions, and geographical requirements. The expected reduction ratios in 2024 compared to 2018 are CO (3.0%), NO_x (7.9%), VOCs (0.7%), SO_x (0.1%), PM₁₀ (2.4%), PM_2.5 (6.1%), NH₃ (0.05%). The reduced PM_2.5 concentration ratio was highest in July and lowest in April. The expected concentration reduction of yearly mean PM_2.5 in the research region is 0.12 ㎍/m³ (0.6%). Conclusions: Gyeonggi-do is now able to quickly provide air pollutant emission reduction calculations by respective policy scenario and PM_2.5 simulation results, including for secondary aerosol particles. In order to provide more generalized results to basic local governments, it is necessary to conduct additional research by expanding the analysis tools and periods.

• Journal of the Korean Association of Geographic Information Studies
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• v.5 no.3
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• pp.87-98
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• 2002

Point & nonpoint source pollutant loads were calculated in Juam lake watershed using GIS, and water quality was simulated using water quality model. Point source pollutant loads were estimated using the unit pollutant loads presented by the Ministry of Environment(MOE, 1998). Nonpoint source pollutant loads were estimated using the value of the direct runoff multiplied by expected mean concentration. The direct runoff was calculated using SCS curve number method. Water quality simulation was conducted using WASP model(2001) developed by U.S. EPA. In order to apply the model, Juam lake watershed was divided into 44 subbasins according to slope, elevation, soil type, landuse and precipitation. Then the model was applied to one subbasin. Simulation results were compared to observed values and the result should good agreement with each other.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.157-160
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• 2010

Management of indoor air quality of underground subway station is an important issue since the limited natural ventilation, limited sunshine incoming, and highly moistured atmosphere. The improvement in IAQ of platform is expected because most stations were installed with platform screen door currently, however, the poor air quality in tunnel might be affecting subway cabin indoor. In this study, we developed the air quality assessment model based on computational fluid dynamics. The geometry of air ventilation unit, seat, LCD monitors, and passengers were modeled using commercial software (Design Modeler) and fluid pattern and pollutants trajectories were analyzed by using CFX. We predicted the thermal comfort by predicted mean vote (PMV), distribution of CO2 and PM10 concentration. It is expected that this model can be used for the performance test of air cleaners which are under development.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.1
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• pp.7-16
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• 1994

This study was designed to establish the relationship between airborne trichloroethylene concentrations and total trichloro-compounds and trichloroacetic acid in urine samples of the trichloroethylene exposed workers, to examine if the biological screening value for trichloroacetic acid in urine set by the Ministry of Labor is appropriate, and to suggest a suitable biological screening value for total trichloro-compounds in urine. Seventy male workers from the cleaning, the packing, and the inspcetion areas were selected as the study group and eighty male office workers were chosen as the control group. The results were as follows: 1. The mean values of total trichloro-compounds and trichloroacetic acid in the exposed group ($48.1{\pm}1.5mg/{\ell}$, $19.7{\pm}1.9mg/{\ell}$) were significantly higher than those in the control group($4.3{\pm}1.5mg/{\ell}$, $1.8{\pm}1.2mg/{\ell}$). 2. The airborne tichloroethylene concentrations were significantly related with the concentrations of total trichloro-compounds in urine(r=0.8212) and the concentrations of trichloroacetic acid in urine(r=0.7216). 3. The average trichloroethylene concentrations in the manual cleaning plants and that in the automatic cleaning plants were 40.1 ppm and 7.7 ppm, respectively. The difference between two groups was statistically significant. 4. The geometric mean of 49.6 ppm trichloroethylene concentration was resulted in the $185.4mg/{\ell}$ total trichloro-compounds in urine, and the 50 ppm trichloroethylene concentration was expected to produce $170.4{\pm}28.5mg/{\ell}$ total trichloro-compounds in urine. 5. With the geometric mean of 49.6 ppm trichloroethylene concentration, the corresponding geometric mean concentration of trichloroacetic acid in urine was $74.7mg/{\ell}$. In conclusion, the level of personal exposure to trichloroethylene concentration was significantly correlated with the concentrations of total trichloro-compounds and trichloroacetic acid in urine. Current biological screening value of $75mg/{\ell}$ for trichloroacetic acid in urine set by the Ministry of Labor was thought to be appropriate, and a biological screening value for total trichloro-compounds in urine should be set in the range of $170.4{\pm}28.5mg/{\ell}$ as a reference value for trichoroethylene exposure.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.3
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• pp.193-202
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• 2009

This study was conducted to identify the magnitude of first flush in small city urban area and to provide the basic information on the criteria of stormwater runoff management. Monitoring site was surrounded by residential area in Gumi city near to national industrial complex and the monitoring period was three months. Total watershed area was 24.9 ha, where 80% of the area is impervious (asphalt of pavement type). Periodic monitoring of conventional water quality parameters were conducted with six times of rainfall period. Event mean and site mean concentrations for all the parameters were calculated based on the analytical results. Particle size distribution was 9.82 ${\mu}m$ for $D_{0.1}$, 38.99 ${\mu}m$ for $D_{0.5}$ and 159.61 ${\mu}m$ for $D_{0.9}$ respectively. First flush phenomenon was detected highly in particulate solids than dissolved ones. The first flush criteria results by mass first flush contained between 44.4% to 58.5% pollutant mass during the first 30% of runoff volume. Mass first flush ratio and particle size distribution obtained in this study are expected to provide the basic information for the design and operation of non-point source treatment facility.