• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.288-294
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• 2011

BACKGROUND: Methylmercury is analyzed by HPLC-ICP/MS because of the simplicity for sample preparation and interference. However, most of the pre-treatment methods for methylmercury need a further pH adjustment of the extracted solution and removal of organic matter for HPLC. The purpose of this study was to establish a rapid and accurate analytical method for determination of methylmercury in fish by using HPLC-ICP/MS. METHOD AND RESULTS: We conducted an experiment for pre-treatment and instrument conditions and analytical method verification. Pre-treatment condition was established with aqueous 1% L-cysteine HCl and heated at $60^{\circ}C$ in microwave for 20 min. Methylmercury in $50{\mu}L$ of filtered extract was separated by a C18 column and aqueous 0.1% L-cysteine HCl + 0.1% L-cysteine mobile phase at $25^{\circ}C$. The presence of cysteine in mobile phase and sample solution was essential to eliminate adsorption, peak tailing and memory effect problems. Correlation coefficient($r^2$) for the linearity was 0.9998. The limits of detection and quantitation for this method were 0.15 and $0.45{\mu}g/kg$ respectively. CONCLUSION: Result for analytical method verification, accuracy and repeatability of the analytes were in good agreement with the certified reference materials values of methylmercury at a 95% confidence level. The advantage of the established method is that the extracted solution can be directly injected into the HPLC column without additional processes and the memory effect of mercury in the ICP-MS can be eliminated.

• Korean Journal of Poultry Science
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• v.43 no.2
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• pp.111-118
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• 2016

Mycotoxins are secondary metabolites produced by molds, such as Aspergillus, Fusarium and Penicillium, that have adverse effects on animals and humans. Aflatoxin, ochratoxin, zearalenone, fumonisin and deoxynivalenol are the mycotoxins of greatest agro-economic importance and cause acute disease called mycotoxicoses. Mycotoxicosis in poultry birds results in decreased meat/egg production, immunosuppressant, and hepatotoxicosis. Some of toxins or their metabolites may be retained in animal or human tissues and induce health problems. This study was designed to develop a sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the simultaneous detection and quantification of mycotoxins, such as aflatoxin $B_1$, aflatoxin $M_1$, ochratoxin A, zearalenone, fumonisin B and deoxynivalenol, in chicken liver and kidney tissues. The mycotoxins were extracted and purified using modified QUECHERS methods, separated by LC and detected by an electrospray ionisation interface (ESI) and tandem MS. Good precision and linearity were observed for most of six mycotoxins. The recovery test for each mycotoxin in liver and kidney tissues mostly indicated good average recovery rates between 80.94% and 98.10% and the coefficient of variation mostly under 13.78%, except for aflatoxin $M_1$ and fumonisin $B_1$. The limit of detection (LOD) for six mycotoxins was $7.6{\sim}145.79{\mu}g/kg$ in liver tissues and $6.07{\sim}197.20{\mu}g/kg$ in kidney tissues. The quantification limits (LOQ) for 6 mycotoxins were in the range $23.04{\sim}441.78{\mu}g/kg$ in liver tissues and $18.40{\sim}597.59{\mu}g/kg$ in kidney tissues, respectively. The developed multi-mycotoxin method in this study permits simultaneous, simple, and rapid determination of several co-existing mycotoxins in chicken liver and kidney tissues.

• Journal of Food Hygiene and Safety
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• v.29 no.4
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• pp.305-311
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• 2014

Minimum infective dose (MID) data has been recognized as an important and absolutely needed in quantitative microbiological assessment (QMRA). In this study, we performed a comprehensive literature review and meta-analysis to better quantify this association. The meta-analysis applied a final selection of 82 published papers for total 12 species foodborne disease pathogens (bacteria 9, virus 2, and parasite 1 species) which were identified and classified based on the dose-response models related to QMRA studies from PubMed, ScienceDirect database and internet websites during 1980-2012. The main search keywords used the combination "food", "foodborne disease pathogen", "minimum infective dose", and "quantitative microbiological risk assessment". The appropriate minimum infective dose for B. cereus, C. jejuni, Cl. perfringens, Pathogenic E. coli (EHEC, ETEC, EPEC, EIEC), L. monocytogenes, Salmonella spp., Shigella spp., S. aureus, V. parahaemolyticus, Hepatitis A virus, Noro virus, and C. pavum were $10^5cells/g$ (fi = 0.32), 500 cells/g (fi = 0.57), $10^7cells/g$ (fi = 0.56), 10 cells/g (fi = 0.47) / $10^8cells/g$ (fi = 0.71) / $10^6cells/g$ (fi = 0.70) / $10^6cells/g$ (fi = 0.60), $10^2{\sim}10^3cells/g$ (fi = 0.23), 10 cells/g (fi = 0.30), 100 cells/g (fi = 0.32), $10^5cells/g$ (fi = 0.45), $10^6cells/g$ (fi = 0.64), $10{\sim}10^2particles/g$ (fi = 0.33), 10 particles/g (fi = 0.71), and $10{\sim}10^2oocyst/g$ (fi = 0.33), respectively. Therefore, these results provide the preliminary data necessary for the development of foodborne pathogens QMRA.

• Journal of Food Hygiene and Safety
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• v.29 no.4
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• pp.299-304
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• 2014

The dose-response models are important for the quantitative microbiological risk assessment (QMRA) because they would enable prediction of infection risk to humans from foodborne pathogens. In this study, we performed a comprehensive literature review and meta-analysis to better quantify this association. The meta-analysis applied a final selection of 193 published papers for total 43 species foodborne disease pathogens (bacteria 26, virus 9, and parasite 8 species) which were identified and classified based on the dose-response models related to QMRA studies from PubMed, ScienceDirect database and internet websites during 1980-2012. The main search keywords used the combination "food", "foodborne disease pathogen", "dose-response model", and "quantitative microbiological risk assessment". The appropriate dose-response models for Campylobacter jejuni, pathogenic E. coli O157:H7 (EHEC / EPEC / ETEC), Listeria monocytogenes, Salmonella spp., Shigella spp., Staphylococcus aureus, Vibrio parahaemolyticus, Vibrio cholera, Rota virus, and Cryptosporidium pavum were beta-poisson (${\alpha}=0.15$, ${\beta}=7.59$, fi = 0.72), beta-poisson (${\alpha}=0.49$, ${\beta}=1.81{\times}10^5$, fi = 0.67) / beta-poisson (${\alpha}=0.22$, ${\beta}=8.70{\times}10^3$, fi = 0.40) / beta-poisson (${\alpha}=0.18$, ${\beta}=8.60{\times}10^7$, fi = 0.60), exponential (r=$1.18{\times}10^{-10}$, fi = 0.14), beta-poisson (${\alpha}=0.11$, ${\beta}=6,097$, fi = 0.09), beta-poisson (${\alpha}=0.21$, ${\beta}=1,120$, fi = 0.15), exponential ($r=7.64{\times}10^{-8}$, fi = 1.00), betapoisson (${\alpha}=0.17$, ${\beta}=1.18{\times}10^5$, fi = 1.00), beta-poisson (${\alpha}=0.25$, ${\beta}=16.2$, fi = 0.57), exponential ($r=1.73{\times}10{-2}$, fi = 1.00), and exponential ($r=1.73{\times}10^{-2}$, fi = 0.17), respectively. Therefore, these results provide the preliminary data necessary for the development of foodborne pathogens QMRA.

• Journal of Cadastre & Land InformatiX
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• v.48 no.2
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• pp.79-98
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• 2018

The purpose of this study is to suggest a model analysing spatio-temporal characteristics of the civil complaints for the officially assessed land price based on big data mining. Specifically, in this study, the underlying reasons for the civil complaints were found from the spatio-temporal perspectives, rather than the institutional factors, and a model was suggested monitoring a trend of the occurrence of such complaints. The official documents of 6,481 civil complaints for the officially assessed land price in the district of Jung-gu of Incheon Metropolitan City over the period from 2006 to 2015 along with their temporal and spatial poperties were collected and used for the analysis. Frequencies of major key words were examined by using a text mining method. Correlations among mafor key words were studied through the social network analysis. By calculating term frequency(TF) and term frequency-inverse document frequency(TF-IDF), which correspond to the weighted value of key words, I identified the major key words for the occurrence of the civil complaint for the officially assessed land price. Then the spatio-temporal characteristics of the civil complaints were examined by analysing hot spot based on the statistics of Getis-Ord $Gi^*$. It was found that the characteristic of civil complaints for the officially assessed land price were changing, forming a cluster that is linked spatio-temporally. Using text mining and social network analysis method, we could find out that the occurrence reason of civil complaints for the officially assessed land price could be identified quantitatively based on natural language. TF and TF-IDF, the weighted averages of key words, can be used as main explanatory variables to analyze spatio-temporal characteristics of civil complaints for the officially assessed land price since these statistics are different over time across different regions.

• Journal of Bio-Environment Control
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• v.28 no.3
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• pp.197-203
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• 2019

This study was carried out to investigate the effect of chlorine water and plasma gas treatment on the quality and microbial control of Latuca indica L. baby Leaf during storage. Latuca indica L. baby leaves were harvested from a plant height of 10cm. They were sterilized with $100{\mu}L{\cdot}L^{-1}$ chlorine water and plasma-gas (1, 3, and 6hours), and packaged with $1,300cc{\cdot}m^{-2}{\cdot}day^{-1}{\cdot}atm^{-1}$ films and then stored at $8{\pm}1^{\circ}C$ and RH $85{\pm}5%$ for 25days. During storage, the fresh weight loss of all treatments were less than 1.0%, and the carbon dioxide and oxygen concentrations in packages were 6-8% and 16-17%, respectively for all treatments in the final storage day. The concentration of ethylene in the packages fluctuated between $1-3{\mu}L{\cdot}L^{-1}$ during the storage and the highest concentration of ethylene was observed at 6 hours plasma treatment in the final storage day. The off-odor of all treatments were almost odorless, the treatments of chlorine water and 1 hour plasma maintained the marketable visual quality until the end of storage. Chlorophyll content and Hue angle value measured at the final storage day were similar to those measured before storage in chlorine water and 1 hour of plasma treatments. E. coli was not detected immediately after sterilization in all sterilization treatments. After 6 hours of plasma treatment, the total bacteria fungus counts were lower than the domestic microbial standard for agricultural product in all sterilization treatments. The total aerobic counts in the end storage day increased compared to before storage, whereas E. coli was not detected in all sterilization treatments. The sterilization effect against bacteria and fungi was the best in chlorine water treatment. Plasma treatment showed sterilization effects, but within a prolonged period of time. In addition, the sterilization effect decreased gradually. These results suggest that chlorine water and plasma treatment were effective in maintaining Latuca indica L. baby Leaf commerciality and controlling microorganisms during postharvest storage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.19-25
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• 2019

The CleanSYS(Clean SYStem) is operated to monitor air pollutants emitted from specific industrial complexes in Korea. So the industrial complexes without the system are directly monitored by the control officers. For efficient monitoring, studies using various sensors have been conducted to monitor air pollutants emitted from industrial complex. In this study, hyperspectral sensors were used to model and verify the equations for estimating the concentration of $NO_2$(nitrogen dioxide) in air pollutants emitted. For development of the equations, spectral radiance were observed for $NO_2$ at various concentrations with different SZA(Solar Zenith Angle), VZA(Viewing Zenith Angle), and RAA(Relative Azimuth Angle). From the observed spectral radiance, the calculated value of the difference between the values of the specific wavelengths was taken as an absorption depth, and the equations were developed using the relationship between the depth and the $NO_2$ concentration. The spectral radiance mixed gas of $NO_2$ and $SO_2$(sulfur dioxide) was used to verify the equations. As a result, the $R^2$(coefficient of determination) and RMSE(Root Mean Square Error) were different from 0.71~0.88 and 72~23 ppm according to the form of the equation, and $R^2$ of the exponential form was the highest among the equations. Depending on the type of the equations, the accuracy of the estimated concentration with varying concentrations is not constant. However, if the equations are advanced in the future, hyperspectral sensors can be used to monitor the $NO_2$ emitted from the industrial complex.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1061-1071
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• 2018

A subsea tunnel, being a super-sized underground structure must ensure safety at the time of earthquake, as well as at ordinary times. At the time of earthquake, in particular, of a subsea tunnel, a variety of response behaviors are induced owing to relative rigidity to the surrounding ground, or difference of displacement, so that the behavior characteristics can be hardly anticipated. The investigation aims to understand the behavior characteristics switched by earthquake of an imaginary subsea tunnel which passes through a fault zone having different physical properties from those of the surrounding ground. In order to achieve the aim, dynamic response behaviors of a subsea tunnel which passes through a fault zone were observed by means of indoor experiments. For the sake of improved earthquake resistance, a shape of subsea tunnel to which flexible segments have been applied was considered. Afterward, it is believed that a D/B can be established through 3-dimensional earthquake resistance interpretation of various grounds, on the basis of verified results from the experiments and interpretations under various conditions. The present investigation performed 1 g shaking table test in order to verify the result of 3-dimensional earthquake resistance interpretation. A model considering the similitude (1:100) of a scale-down model test was manufactured, and tests for three (3) Cases were carried out. Incident seismic wave was introduced by artificial seismic wave having both long-period and short-period earthquake properties in the horizontal direction which is rectangular to the processing direction of the tunnel, so that a fault zone was modeled. For numerical analysis, elastic modulus of the fault zone was assumed 1/5 value of the modulus of individual grounds surround the tunnel, in order to simulate a fault zone. Resultantly, reduced acceleration was confirmed with increase of physical properties of the fault zone, and the result from the shaking table test showed the same tendency as the result from 3-dimensional interpretation.

• Ecology and Resilient Infrastructure
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• v.7 no.4
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• pp.227-237
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• 2020

Microclimatic data were measured, and the human thermal sensation was analyzed at 10 local climate zones based on the major land cover classification to investigate the thermal environment of urban areas during summer nighttime. From the results, the green infrastructure areas (GNIAs) showed an average air temperature of 1.6℃ and up to 2.4℃ lower air temperature than the gray infrastructure areas (GYIAs), and the GNIAs showed an average relative humidity of 9.0% and up to 15.0% higher relative humidity. The wind speed of the GNIAs and GYIAs had minimal difference and showed no significance at all locations, except for the forest location, which had the lowest wind speed owing to the influence of trees. The local winds and the surface roughness, which was determined based on the heights of buildings and trees, appeared to be the main factors that influenced wind speed. At the mean radiant temperature, the forest location showed the maximum value, owing to the influence of trees. Except at the forest location, the GNIAs showed an average decrease of 5.5℃ compared to GYIAs. The main factor that influenced the mean radiant temperature was the sky view factor. In the analysis of the human thermal sensation, the GNIAs showed a "neutral" thermal perception level that was neither hot nor cold, and the GYIAs showed a "slightly warm" level, which was a level higher than those of the GNIAs. The GNIAs showed a 3.2℃ decrease compared to the GYIAs, except at the highest forest location, which indicated a half-level improvement in the human thermal environment.

• Korean Journal of Environment and Ecology
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• v.36 no.3
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• pp.338-349
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• 2022

This study aims to investigate whether modular community planting, which entailed planting a variety of species of seedlings at high density, was more effective in restoring natural forests than the existing mature tree planting. We also investigated whether the planting density of the modular community planting facilitates growth or improves the tree layer coverage. We conducted outdoor experiments in which the samples were divided into a mature tree planting plot (control plot), where mature trees were planted at wide intervals, and a modular community planting (MCP) plot (treatment plot), where multiple seedlings were planted in high density. The MCP plot was further divided into the plot in which 3 seedlings were planted per m² and the plot of 1 seedling per m². We measured the specimens' survival rate, growth rate (tree height, crown width, and root collar diameter), and cover rate for 26 months from May 2019 and the predicted future tree height growth using the measured tree height. The survival rate and relative growth rate of the MCP were higher than those of the mature tree planting plot. The vertical coverage rate of the tree crown in the MCP exhibited complete coverage of the ground before 23 months, while the coverage rate of the mature tree planting decreased due to transplantation stress. The seedlings in the MCP, which were planted at high density, grew well and were predicted to grow higher than the mature trees in the large tree planting plot within 5 to 6.5 years after planting. It was due to multiple species, seedlings, high-density planting, and planting foundation improvements, such as soil enhancement and mulching. In other words, the seedlings planted in the MCP had a higher survival rate as their environmental adaptation after planting was better, and their early growth was also larger than the trees in the mature planting plot. The high-density mixed planting of various native species not only mitigated the inter-complementary environmental pressures but also facilitated growth by inducing competition between species. Moreover, the planting foundation improvement effectively increased the seedlings' viability and growth rate. A reduction in follow-up management costs is expected as the tree layer coverage sharply increases due to the higher planting density. In the MCP (3 seedlings per m² and 1 seedling per m²), the tree height growth was promoted with the higher planting density, and the crown width and root collar diameter tended to be larger with the lower planting density, but these differences were not statistically significant.