• 대한기계학회논문집A
• /
• 제29권11호
• /
• pp.1488-1493
• /
• 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.

• 한국환경보건학회지
• /
• 제35권2호
• /
• pp.86-94
• /
• 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
• /
• 한국공간정보시스템학회 2007년도 GIS 공동춘계학술대회 논문집
• /
• pp.246-251
• /
• 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.

• 약학회지
• /
• 제43권6호
• /
• pp.834-842
• /
• 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
• /
• 제34권6호
• /
• pp.551-558
• /
• 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.

• 한국환경보건학회지
• /
• 제49권5호
• /
• pp.275-288
• /
• 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.

• 한국지리정보학회지
• /
• 제5권3호
• /
• pp.87-98
• /
• 2002

광주 전남의 상수원인 주암호 유역에 대해 GIS를 이용하여 점오염원과 비점오염원 부하량을 산정하였으며 기 개발된 모형을 이용하여 수질을 모의하였다. 점오염원 부하량은 환경부에서 발표한 원단위(1998)를 이용하여 산정하였고, 비점오염원 부하량은 유출곡선지수를 이용한 SCS방법으로 직접유출량을 계산한 후 우리나라 유역의 특성에 맞는 토지이용별 기대평균농도 값을 이용하여 산정하였다. 수질모의는 미국환경청에서 개발한 WASP모형(2001)을 이용하였으며 대상유역을 GIS를 이용하여 경사, 방향, 고도, 토양, 토지이용과 강우량에 따라 44개의 소유역으로 구분하고, 그중 하나의 소유역에 대해 모형을 적용하였다. 모형의 결과치를 수질관측치와 비교한 결과 매우 유사함을 알 수 있었다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2010년도 춘계학술대회 논문집
• /
• pp.157-160
• /
• 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.

• 한국산업보건학회지
• /
• 제4권1호
• /
• pp.7-16
• /
• 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.

• 대한환경공학회지
• /
• 제31권3호
• /
• pp.193-202
• /
• 2009

본 연구는 국내 중소 도시지역에서 강우 시 발생하는 강우유출수의 유출경향을 분석하고 초기강우기준을 산정하기 위하여 수행되었다. 연구지역은 국가산업단지가 소속되어 있는 구미시 원평동의 주거지역으로 선정 되었으며 모니터링 기간은 3개월에 걸쳐 시행되었다. 연구지역의 유역면적은 24.9 ha이고, 토지이용형태는 주거지역으로 대상유역의 80%가 불투수 면적(포장의 형태: 아스팔트)인 것으로 나타났다. 모니터링은 총 6회의 강우사상에 대하여 실시하였으며 모든 수질항목에 대해 EMC (Event Mean Concentration)와 SMC (Site Mean Concentration)를 산정하였다. 또한 강우지속시간에 따른 입경크기분포의 변화와 초기세척 현상을 관찰하였는데, 입경크기분포는 10%입경($D_{0.1}$), 50%입경($D_{0.5}$, 90%입경($D_{0.9}$이 각각 9.82 ${\mu}m$, 38.99 ${\mu}m$, 159.61 ${\mu}m$로 나타났고, 초기세척 현상은 용존성 물질보다 입자성 물질이 더 강하게 나타났다. $MFF_n$ (Mass first flush)을 이용하여 초기강우기준을 검토한 결과 초기우수유출수의 부피 30%에 오염물질부하량의 부피 44.4~58.5%를 포함하고 있는 것으로 나타났다. $MFF_n$과 입경크기분포는 자연형, 장치형 시설과 같은 다양한 비점오염저감시설의 설계 및 운전과 초기강우기준 결정을 위한 정보를 제공할 수 있을 것으로 기대된다.