• The Journal of Engineering Geology
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• v.19 no.3
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• pp.365-371
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• 2009

This paper address the characteristics of loading pollutants caused by the unit agricultural area to establish an efficient management method in NPS (non-point source). The relationship between rainfall and runoff shows good coefficient with 0.92, when the event which shows relatively long antecedent dry days is excepted. The impact of runoff volume on the runoff coefficient can be described by the rainfall intensity strongly. The pollutant EMCs (event mean concentrations) in runoff increased by the increase of antecedent dry days due to dry soil conditions. As the similar pattern of pollutant's loads such as TSS, BOD, COD, TN and TP, it is cleared that other pollutants can be removed when TSS is removed. Therefore the system using only runoff coefficients is not sufficient for the prediction of pollutant loads. It is necessary to consider soil conditions such as rainfall, antecedent dry day, antecedent rainfall etc. for the prediction system.

• Wind and Structures
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• v.23 no.6
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• pp.559-575
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• 2016

In order to investigate the influence of different blade positions on aerodynamic load and wind loads and load-effects of large scale wind turbine tower under the halt state, we take a certain 3 MW large scale horizontal axis three-blade wind turbine as the example for analysis. First of all, numerical simulation was conducted for wind turbine flow field and aerodynamic characteristics under different halt states (8 calculating conditions in total) based on LES (large eddy simulation) method. The influence of different halt states on the average and fluctuating wind pressure coefficients of turbine tower surface, total lift force and resistance coefficient, circular flow and wake flow characteristics was compared and analysed. Then on this basis, the time-domain analysis of wind loads and load-effects was performed for the wind turbine tower structure under different halt states by making use of the finite element method. The main conclusions of this paper are as follows: The halt positions of wind blade could have a big impact on tower circular flow and aerodynamic distribution, in which Condition 5 is the most unfavourable while Condition 1 is the most beneficial condition. The wind loads and load-effects of disturbed region of tower is obviously affected by different halt positions of wind blades, especially the large fluctuating displacement mean square deviation at both windward and leeward sides, among which the maximum response occurs in $350^{\circ}$ to the tower top under Condition 8; the maximum bending moment of tower bottom occurs in $330^{\circ}$ under Condition 2. The extreme displacement of blade top all exceeds 2.5 m under Condition 5, and the maximum value of windward displacement response for the tip of Blade 3 under Condition 8 could reach 3.35 m. All these results indicate that the influence of halt positions of different blades should be taken into consideration carefully when making wind-resistance design for large scale wind turbine tower.

• Environmental Analysis Health and Toxicology
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• v.30
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• pp.11.1-11.19
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• 2015

Objectives The objective of this study was to conduct a systematic review to provide summarized evidence on the association between maternal exposure to particulate air pollution and birth weight (BW) and preterm birth (PTB) after taking into consideration the potential confounding effect of maternal smoking. Methods We systematically searched all published cohort and case-control studies examining BW and PTB association with particulate matter (PM, less than or equal to $2.5{\mu}m$ and $10.0{\mu}m$ in diameter, $PM_{2.5}$ and $PM_{10}$, respectively) from PubMed and Web of Science, from January 1980 to April 2015. We extracted coefficients for continuous BW and odds ratio (OR) for PTB from each individual study, and meta-analysis was used to combine the coefficient and OR of individual studies. The methodological quality of individual study was assessed using a standard protocol proposed by Downs and Black. Forty-four studies met the inclusion criteria. Results In random effects meta-analyses, BW as a continuous outcome was negatively associated with $10{\mu}g/m^3$ increase in $PM_{10}$ (-10.31 g; 95% confidence interval [CI], -13.57 to -3.13 g; I-squared=0%, p=0.947) and $PM_{2.5}$ (-22.17 g; 95% CI, -37.93 to -6.41 g; Isquared=92.3%, p<0.001) exposure during entire pregnancy, adjusted for maternal smoking. A significantly increased risk of PTB per $10{\mu}g/m^3$ increase in $PM_{10}$ (OR, 1.23; 95% CI, 1.04 to 1.41; I-squared=0%, p=0.977) and $PM_{2.5}$ (OR, 1.14; 95% CI, 1.06 to 1.22; I-squared=92.5%, p<0.001) exposure during entire pregnancy was observed. Effect size of change in BW per $10{\mu}g/m^3$ increase in PM tended to report stronger associations after adjustment for maternal smoking. Conclusions While this systematic review supports an adverse impact of maternal exposure to particulate air pollution on birth outcomes, variation in effects by exposure period and sources of heterogeneity between studies should be further explored.

• Analytical Science and Technology
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• v.24 no.2
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• pp.142-149
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• 2011

This study was conducted to define metabolite of the resveratrol by gas chromatography- time-offlight mass spectrometric detection. From these results, we suppose that the structure of metabolite is the result of reduction of double-bond attached by two-phenyl groups. Also, validity of method for determining metabolite of resveratrol and endogenous steroids was tested. The recoveries ranged from 96.47 to 114.74%, and intraand inter-day precision ranged 11.40 - 10.87% and 1.10 - 10.93%, accuracy ranged 80.03 - 119.92% and 80.02 - 119.56%, respectively. Resveratrol and endogenous steroids had correlation coefficients above or equal to 0.996. The method was successfully validated for the determination of resveratrol and endogenous steroids. Urinary samples from volunteers dosed resveratrol were analyzed to confirm a correlation resveratrol and its metabolite. From these results, the highest level of resveratrol and its metabolite was excreted in 10 - 15 hr more slowly than common drug, and conversion rate of metabolite was higher in woman than that in man. In addition, endogenous steroids were shown same the highest level of 10 - 15 hr. For estrone and estradiol, sensitivity was relatively higher in female than in man. And there were no significant changes of excretion patterns in the other endogenous steroids. Thus, we assumed that activation of resveratrol has impact on woman than man.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.5
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• pp.480-496
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• 2017

CMAQ (Community Multiscale Air Quality)-HDDM (High-order Direct Decoupled Method) simulations with MICS-Asia 2010 and INTEX-B 2006 emissions inventories were performed to investigate the impact of Chinese $NO_x$ and VOC emissions on 1-hr ozone concentrations over South Korea during May to July in 2014. Chinese $NO_x$ and VOC emissions in MICS-Asia 2010 were 60% higher and 100% lower than those in INTEX-B 2006 during the simulation period. It makes the ratio of Chinese VOC to $NO_x$ emissions in INTEX-B 2006 (Case 1) is 3.2 times higher than that in MICS-Asia 2010 (Case 2). When the observed period mean 1-hr ozone concentration averaged across 106 air monitoring sites in the SMA (Seoul Metropolitan Area) was 37.6 ppb, the modeled values were similar to each other; 37.3 ppb for Case 1, and 40.4 ppb for Case 2. Both cases show that daily maximum 1-hr ZOC (Zero-Out Contribution) of Chinese $NO_x$ and VOC emissions were as high as 55 ppb and 35 ppb for the episode respectively. Correlation coefficients between ZOC of Chinese $NO_x$ and VOC emissions and the SMA daily maximum 1-hr ozone were 0.49~0.69. It indicates that Chinese emissions occasionally affect the SMA daily ozone peaks. On the other hand, Case 2 predicted 7 ppb and 1 ppb higher ZOC of Chinese $NO_x$ and VOC emissions than Case 1, when simulated ozone in the SMA is over 80 ppb. It implies that upwind $NO_x$ emissions would be more important than upwind VOC emissions for the long-range transport of ozone in Northeast Asia.

• Korean Journal of Applied Biomechanics
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• v.16 no.3
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• pp.105-115
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• 2006

The purpose of this study is to elucidate the mechanical characteristics of lower extremity joint movements at different walking speeds in obese people and suggest the very suitable exercise for obese person's own body weight and basic data for clinical application leading to medical treatment of obesity. This experimental subjects are all males between the ages of 20 and 30, who are classified into two groups according to Body Mass Index(BMI): one group is 15 people with normal body weight and the other 15 obese people. Walking speed is analysed at 3 different speeds ($1.5^m/s$, $1.8^m/s$, $2.1^m/s$) which is increased by $0.3^m/s$ from the standard speed of $1.5^m/s$. We calculated joint moments of lower extremity during stance phase through video recording and platform force measurement.Two-way ANOVA(Analysis of Variance, Mix) is applied to get the difference of moments according to walking speeds between normal and obese groups. Pearson's Correlation Analysis is applied to look into correlation between walking speeds and joint moments in both groups. Significance level of each experiment is set as ${\alpha}=.05$. As walking speed increases maximum ankle plantar flexion moment in the stance phase is smaller in obese group than in normal group, which is suggestive of weak toe push-off during terminal stance in obese group, and the highest maximum ankle plantar flexion moment in obese group during the middle speed walking($1.8^m/s.$). Maximum ankle dorsal flexion moment in obese group is relatively higher than in normal group and this is regarded as a kind of compensatory mechanism to decrease the impact on ankle when heel contacts the floor. Maximum knee flexion and extension moments are both higher in normal group with an increase tendency proportional to walking speed and maximum hip flexion and extension moments higher in obese group. In summary, maximum ankle plantar flexion moment between groups(p<.025), maximum knee moment not in flexion but in extension(p<.001) within each group according to increasing walking speed, and maximum hip flexion and extension moment(p<.001 and p<.004, respectively according to increasing walking speed are statistically significant but knee and hip moments between groups are not. Pearson correlation are different: high correlation coefficients in maximum knee flexion and extension moments, in maximum hip extension moment but not hip flexion, and in maximum ankle dorsal flexion moment but not ankle plantar flexion, in each group. We suspect that equilibrium imbalance develops when the subject increases walking speed and the time is around which he takes his foot off the floor.

• International Commerce and Information Review
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• v.14 no.1
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• pp.87-114
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• 2012

The purpose of this paper is to analyze the economic effects of Foreign Direct Investment(FDI) and human capital using VECM in Korea from 1970 to 2009. Empirical results through VECM show that the coefficients of GDP, GFO(gross fixed capital), LAB(total labor), EXO(export), PCDB(public and commercial loan) and FDI have had a positive impact on Korean economic growth. In contrast, the effects of PCDB and FDI were not as significant as the other variables. In particular, the interaction effect, $FDI^*EDU$(the college graduation variable), was more important than that of the FDI alone. However, the coefficient of $FDI^*EDU$ was not so big. Korean government needs to attract more FDI to enhance Korean economic growth rate by the improvement of investment environment. There are a big amount gap between notification FDI and arrival FDI in Korea. So Korean government and companies should actively persuade foreign investors to invest after their investment notification. Also the Korean college authorities should emphasize more on curriculum which adapts to company skill in the field work.

• Atmosphere
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• v.26 no.3
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• pp.357-372
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• 2016

Northeast Asian regions have recently become the main source of anthropogenic and natural aerosols. Measurement of aerosols on the sea in these regions have been rarely conducted since the experimental campaigns such as ACE-ASIA (Asian Pacific Regional Aerosol Characterization Experiment) in 2001. Research vessel observations of aerosol mass and chemical composition were performed on the Yellow and south sea around the Korean peninsula. The ship measurements showed six representative cases such as aerosol event and non-event cases during the study periods. On non-event cases, the anthropogenic chemical and natural soil composition on the Yellow sea were greater than those on the south sea. On aerosol event cases such as haze, haze with dust, and dust, the measured mass concentrations of anthropogenic chemical and element compositions were clearly changed by the events. In particular, methanesulfonate ($MSA^-$, $CH_3SO_3^-$), a main component of natural oceanic aerosol important for sulfur circulation on Earth, was first observed by the vessel in Korea, and its concentration on the Yellow sea was three times that on the south sea during the study period. Sea salt concentration important to chemical composition on the sea is related to wind speed. Coefficients of determination ($R^2$) between wind speed and sea salt concentration were 0.68 in $PM_{10}$ and 0.82 in $PM_{2.5}$. Maximum wave height was not found to be correlated to the sea salt concentration. When sea-salt comes into contact with pollutants, the total sea-salt mass is reduced, i.e., a loss of $Cl^-$ concentration from NaCl, the main chemical composing sea salt, is estimated by reaction with $HNO_3$(gas) and $H_2SO_4$(gas). The $Cl^-$ concentration loss by $SO_4^{2-}$ and $NO_3^-$ more easily increased for $PM_{10}$ compared to $PM_{2.5}$. The results of this study will be applied to verifying a dust-haze forecasting model. In addition, continued vessel measurements of aerosol data will become important to research for climate change studies in the future.

• Horticultural Science & Technology
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• v.30 no.3
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• pp.270-277
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• 2012

Greenhouse industry has been growing in many countries due to both the advantage of stable year-round crop production and increased demand for fresh vegetables. In greenhouse cultivation, $CO_2$ concentration plays an essential role in the photosynthesis process of crops. Continuous and accurate monitoring of $CO_2$ level in the greenhouse would improve profitability and reduce environmental impact, through optimum control of greenhouse $CO_2$ enrichment and efficient crop production, as compared with the conventional management practices without monitoring and control of $CO_2$ level. In this study, a mathematical model was developed to estimate the $CO_2$ emission from soil as affected by environmental factors in greenhouses. Among various model types evaluated, a linear regression model provided the best coefficient of determination. Selected predictor variables were solar radiation and relative humidity and exponential transformation of both. As a response variable in the model, the difference between $CO_2$ concentrations at the soil surface and 5-cm depth showed are latively strong relationship with the predictor variables. Segmented regression analysis showed that better models were obtained when the entire daily dataset was divided into segments of shorter time ranges, and best models were obtained for segmented data where more variability in solar radiation and humidity were present (i.e., after sun-rise, before sun-set) than other segments. To consider time delay in the response of $CO_2$ concentration, concept of time lag was implemented in the regression analysis. As a result, there was an improvement in the performance of the models as the coefficients of determination were 0.93 and 0.87 with segmented time frames for sun-rise and sun-set periods, respectively. Validation tests of the models to predict $CO_2$ emission from soil showed that the developed empirical model would be applicable to real-time monitoring and diagnosis of significant factors for $CO_2$ enrichment in a soil-based greenhouse.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.5
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• pp.567-577
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• 1996

This study is to estimate population ecological parameters, including growth parameters, survival rates, instantaneous coefficients of natural and fishing mortalities, and age at first capture, as well as growth rates at age of the hairtail, Trichiurus lepturus Linne in Korean waters. For describing the growth of the hairtail, three growth models were fitted, and the von Bertalanffy growth model was adopted for the purpose of the further stock assessment work. The von Bertalanffy growth parameters estimated from a nonlinear regression using EXCEL Solver were $L_\infty=46.01cm$, K=0.3868, and $t_0=-0.3220$. Annual survival rate (S) of the hairtail was estimated to be 0.277 (variance=0.00035) and the instantaneous coefficient of natural mortality (M) was estimated to be 0.441/year. Instantaneous coefficient of fishing mortality (F) for the recent years was calculated as 0.843/year, implying an impact from fishing about two times greater than that of natural mortality. The age at first capture $(t_c)$ was estimated to be 0.787 years, which is much younger age than $50\%$ mature age. Finally, the growth rates at age were estimated.