• Journal of Environmental Health Sciences
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• v.45 no.6
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• pp.622-629
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• 2019

Objectives: The occurrence of norovirus food poisoning in South Korea has been reported since 2003. This study was performed to investigate the characteristics of norovirus food poisoning outbreaks in Korea from 2006 to 2015 and to analyze the relationship between these outbreaks and climate factors. Methods: Data on norovirus food poisoning outbreaks were obtained from the Korea Ministry of Food and Drug Safety. Data on climate factors were obtained from the Korea Meteorological Administration. Frequency analysis and Pearson's correlation analysis were adopted for this study. Results: During the study period, norovirus was the greatest contributing factor of food poisoning outbreaks. Approximately half of the outbreaks of norovirus food poisoning occurred in winter. Average temperature, highest and lowest temperatures, precipitation, number of days with rainfall, and humidity all had a significant negative correlation with monthly number of outbreaks of norovirus food poisoning (p<0.05). Among these, the lowest and average temperature showed higher correlation coefficients. However, the sum of the outbreaks in spring and autumn was similar to that of winter, and more than one-third occurred in group meal-service settings, including school lunches. This was strongly assumed as the use of norovirus-contaminated groundwater for preparation of meals in some settings. Conclusion: The cold and dry of the winter season in Korea may assist the transmission of norovirus. Also, the use of groundwater in group meal service is suspected of inducing a larger scale of norovirus food poisoning. Both health authorities and community-based prevention and control measures are required to respond to these complex etiological outbreaks.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.E1
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• pp.15-28
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• 2004

To study the characteristics of ammonia and the related compounds, atmospheric aerosols and gases were collected using a triple filter pack sampler, a low volume air sampler, and a three-stage Anderson air sampler in Seoul and Kangwha Island, Korea from Dec. 1996 to Oct. 1997. Ammonia concentrations showed approximately two times higher in summer than in winter at both sites. The highest $HNO_3$ levels were generally observed in summertime at two sampling sites. The average mass concentration of $PM_{2.5}$ in heavily industrialized Seoul was about three times higher than that of Kangwha. In winter, the sum of $NH_4^+$ and its counter ions (such as $Cl^-,\;NO_3^-$, and $SO_4^{2-}$) comprised $30-41\%$ of $PM_{2.5}$ mass concentration at each sampling site. Temperature dependence of particulate nitrate was examined at the urban sampling site. The formation of the nitrate in the fine mode was dependent not only on the amount of precursors but also on the variation of temperature. $(NH_4)_2SO_4$ and $NH_4HSO_4$ coexisted with $NH_4NO_3$ and $NH_4Cl$ at each site. According to the summertime backward trajectory analysis, $NO_3^-$ showed higher level with air parcels transported from northeast Asian continent. On the other hand, the concentration of $SO_4^{2-}$ showed significantly higher level when air masses originated from Pacific Ocean, southern part of Japan, and Korea.

• Korean Journal of Remote Sensing
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• v.33 no.4
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• pp.359-375
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• 2017

We developed fog detection algorithm (KNU_FDA) based on the optical and textural properties of fog using satellite (COMS) and ground observation data. The optical properties are dual channel difference (DCD: BT3.7 - BT11) and albedo, and the textural properties are normalized local standard deviation of IR1 and visible channels. Temperature difference between air temperature and BT11 is applied to discriminate the fog from other clouds. Fog detection is performed according to the solar zenith angle of pixel because of the different availability of satellite data: day, night and dawn/dusk. Post-processing is also performed to increase the probability of detection (POD), in particular, at the edge of main fog area. The fog probability is calculated by the weighted sum of threshold tests. The initial threshold and weighting values are optimized using sensitivity tests for the varying threshold values using receiver operating characteristic analysis. The validation results with ground visibility data for the validation cases showed that the performance of KNU_FDA show relatively consistent detection skills but it clearly depends on the fog types and time of day. The average POD and FAR (False Alarm Ratio) for the training and validation cases are ranged from 0.76 to 0.90 and from 0.41 to 0.63, respectively. In general, the performance is relatively good for the fog without high cloud and strong fog but that is significantly decreased for the weak fog. In order to improve the detection skills and stability, optimization of threshold and weighting values are needed through the various training cases.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.2
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• pp.1-8
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• 2011

In this study, In order to evaluate reliable of MODIS GPP, the MODIS GPP and Flux tower measured GPP were compared to evaluate the use of method on 8 days composite MODIS GPP. The 2008 Flux data ($CO_2$ Flux and air temperature) measured in Seolmacheon watershed ($8.48\;km^2$) were used. The Flux tower GPP was estimated as the sum of $CO_2$ Flux and $R_{ec}$ (ecosystem respiration) by Lloyd and Taylor method (1994). The summer Monsoon period from June to August mostly contributed the underestimation of MODIS GPP by cloud contamination on MODIS pixels. The 2008 MODIS GPP and Flux tower GPP of the watershed were $1133.2\;g/m^2/year$ and $1464.3\;g/m^2/year$ respectively and the determination coefficient ($R^2$) after correction of cloud-originated errors was 0.74 (0.63 before correction). Even though effect of Cloud-Originated Errors was eliminated, Solar radiation and Temperature are affected at GPP. Measurement of correct GPP is difficult. But, If errors of MODIS GPP analyze on Cloud Moonsoon Climate in korea and eliminated effect of Cloud-Originated Errors, MODIS GPP will be considered GPP increasing of 9 %. There, Our results indicate that MODIS GPP show reliable and useful data except for summer period in Moonsoon Climate.

• Journal of Electrochemical Science and Technology
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• v.15 no.3
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• pp.388-404
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• 2024

In the present work, the operating parameters were optimized using Box Behnken Design (BBD) in response surface methodology (RSM) to maximize the hydrogen production rate (R₁) and hydrogen production rate per unit watt consumed (R₂) of a proton exchange membrane electrolysis cell (PEMEC), a third response (R₃) which was the sum of the scaled values of R₁ and R₂ were selected to be maximized so that both hydrogen production rate and hydrogen production rate per unit watt consumed could be maximized. The major parameters which were influencing the experiment for enhancing the output responses were oxygen electrode/anode electrocatalyst loading (A), current supplied (B) and water inlet temperature (C). The commercial proton exchange membrane Nafion^® was used as the electrolyte. The acetylene black carbon (C_AB) supported IrO₂ was used as the electrocatalyst for preparing oxygen electrode/anode whereas commercial Pt (40 wt%)/C_HSA was used as the H₂ electrode/cathode electrocatalyst. The quadratic model was developed to predict the output/ responses and their proximity to the experimental output values. The developed model was found to be significant as the P values for both the responses were < 0.0001 and F values were greater than 1. The optimum condition for both the responses were O₂ electrode/anode electrocatalyst loading of 1.78 mg/cm², supplied current of 0.33 A and water inlet temperature of 54℃. The predicted values for hydrogen production rate (R₁) and hydrogen production rate per unit watt consumed (R₂) were 2.921 mL/min and 2.562 mL/(min·W), respectively obtained from the quadratic model. The error % between the predicted response values and experimental values were 1.47% and 3.08% for R₁ and R₂, respectively. This model predicted the optimum conditions reasonably in good agreement with the experimental conditions for the enhancement of the output responses of the developed PEM based electrolyser.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.5
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• pp.315-320
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• 2006

This paper describes stress analysis and fatigue limit evaluation of plate with V-notch and hole-notch by lock-in infrared thermography. Temperature variation of a specimen under cyclic loading is negatively proportional to the sum of principle stress change and the surface temperature measured by infrared camera is calculated to the stress of notch specimens, based on thermoelastic equation. And also, fatigue limitation can be evaluated by the change of intrinsic energy dissipation. Fatigue limitation of two notch specimens is evaluated as 164 MPa and 185 MPa, respectively and the stress measured by Lock-in infrared Thermography show good agreement within 10% error.

• Journal of ILASS-Korea
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• v.23 no.4
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• pp.175-184
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• 2018

Emission characteristics of regulated (NOx, PM, CO, NMHC) and unregulated (VOCs, aldehydes, PAHs) air pollutants were investigated for diesel heavy duty buses equipped with different after-treatment systems (DPF+EGR and SCR) under urban driving cycle. The combustion temperature and the working temperature of SCR catalysts were important to make impact on NOx emissions, whereas PM emissions were low. The alkane groups dominated NMVOCs emissions, making 42.6~59.4% of sum of the NMVOCs emissions. Especially, alkane emissions of DPF+EGR-equipped vehicle included DOC had 14.9~15.5% higher than those of SCR-equipped vehicle due to low efficiency of oxidation catalyst. In the case of individual NMVOCs, n-nonane and propylene emissions highly occupied for DPF+EGR and SCR, respectively. Formaldehyde emissions among aldehydes were the highest and PAHs emissions were hardly detected except naphthalene and phenanthrene. The NMHC speciation has been shown to be the highest of the formaldehyde ranged 20.8~21.5%. The results of this study will be contributed to establish Korean HAPs emission inventory for automobile source.

• Journal of Korea Society of Industrial Information Systems
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• v.23 no.2
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• pp.19-28
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• 2018

In this paper, we studied on the sampling of ocean meteorological data to analyze signature of naval ships. The newest ocean meteorological data, that was quality controled by the Korea Meteorological Administration(KMA), was collected. Outliers were removed from the data by setting the usable range of data. After that, the data size was reduced through the random sampling method, taking geopolitical significance and effective area of buoy, for probabilistic analysis. Moreover, the sample sizes were set at 100, 200, and 400 by considering the population size and a 95% confidence level. The final sample was obtained using the two-dimensional stratified sampling method based on highly correlated water temperature and air temperature. The sum of the squared errors and the confidence interval was calculated to compare the result of sampling. As a result, this study proposed reasonable sample size for infra­red signature analysis of naval ships.

• The Research Journal of the Costume Culture
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• v.22 no.3
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• pp.431-439
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• 2014

This research verified the usefulness and practicality of citrus peel extract as a natural dye. This study dyed cotton, silk, and cotton/mulberry fiber blended fabrics using citrus peel extract, and measured the dyeability and functional property to verify their usefulness and practicality. The dyeing affinity of the citrus peel extract was measured by dyeing under alkaline conditions to determine the temperature and time for optimal dyeing conditions of the solution. The results show that a temperature and time of $60^{\circ}C$ and 30 minutes were optimal for dyeing cotton fabrics with citrus peel extract, $50^{\circ}C$ and 60 minutes for silk fabrics, and $60^{\circ}C$ and 60 minutes for cotton/mulberry fiber blended fabrics, respectively. In addition the results of measuring the color fastness of the cotton, silk, and cotton/mulberry fiber blended fabrics dyed with the citrus peel extract show that the color fastness was superior for washing, friction, sweat, and water. However, the color fastness for sunlight appeared to be slightly weak. In addition, it was found that fabric dyed with the citrus peel extract showed partial antimicrobial properties. The antimicrobial property appeared the greatest in the silk fabric. The cotton/mulberry fiber blended fabrics had 90% or more Staphylococcus aureus present, but the antimicrobial properties were not high in the cotton fabric. Additionally, the heavy metal content, which is harmful to the human body, appeared to be lower than standard figures, so the dye was found to be innocuous to humans. Therefore, when the results of this study are put together, citrus peel extract is sufficiently useful and practical as an ingredient for a natural dye. Moreover, there is ample possibility to develop citrus peel dyed fabrics as environmentally friendly fashion materials.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.122.2-122.2
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• 2011

Sulfur hexafluoride ($SF_6$), one of the most potent greenhouse gases, is known as a hydrate former and has been studied at the high pressure up to 1.3 GPa with gas mixtures and with aqueous surfactant. Since we regard $SF_6$ as a potential promoter molecule that can stabilize hydrate structure more effectively compare to the other promoters, further investigation is required to verify the stabilizing ability of $SF_6$ in the hydrate structure. However, the insoluble nature of $SF_6$ in water or gases hinders fine scale analyses. This work discusses the data obtained by using molecular dynamics simulations of structure II (sII) clathrate hydrates containing $SF_6$ and $H_2$. The simulations were performed using the TIP4P/Ice model for water molecule and a previously reported $SF_6$ molecular model (optimized at the pure $SF_6$ single phase system (Olivet and Vega, 2007)), and a $H_2$ molecular model (adapted from the THF+$H_2$ hydrate system (Alavi et al., 2006)). The simulations are performed to observe the stability of $SF_6$ and $H_2$ in the sII clathrate hydrate system with varying temperature and pressure conditions and occupancies of $SF_6$ and $H_2$, which cannot be easily tuned experimentally. We observe that stability of H2 enclathrated in the hydrate structure more affected by the occupancy of $SF_6$ molecules and temperature than pressure, which ranges from 1 to 100 bar.