• Economic and Environmental Geology
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• v.34 no.5
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• pp.485-498
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• 2001

This study was objected to identify the temporal and spatial variations oi groundwater quality and contamination using monthly groundwater monitoring data collected from 30 wells in Daejung watershed, Jeju Island. Water samples were analyzed for major cations. anions, and environmental isotopes including $^{18}0-H_2$O,$^{2}H-H_2$O and$^{15}$ N-NO$_3$The groundwater represented mostly Na(Mg)-HCO$_3$ type, with local change toward Ca-HCO$_3$ type and Na-Cl type. Groundwater quality depends upon various factors such as the local groundwater flowpaths, input of surface contaminants with recharge events, and sea-water intrusion along the coastal area. Nitrate contamination changed temporally according to recharge events and spatially. $\delta$$^{18}$ O-$\delta$$_2$H data for monthly sampled groundwaters showed distinctive clusters, implying that groundwater was originated from independent precipitation, and subsequently recharged very fash. Using$\delta$$^{15}$ N-NO$_3$ data, major sources of nitrate and its areas of influence could be identified. The areas under influence of livestock farms showed relatively high NO$_3$-N concentrations and$\delta$$^{15}$ N values higher than 5$\textperthousand$. The agricultural areas in southeastern part showed very high concentrations of NO$_3$-N with the $\delta$$^{15}$ N values of lower than 5$\textperthousand$.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.145-150
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• 2015

Needs about safety of residents are important in urbanized society, elderly and small-size family. People are looking for safety information system and device of CPTED. That is, Needs and Installations of CCTV increased steadily. But, scientific analysis about validity, systematic plan and location of security CCTV is nonexistent. It is simply put these devised in more demanded areas. It has limits to look for safety of residents by increasing density of CCTVs. One of the characteristics of crime is clustering and stong interconnectivity. So, exploratory spatial data of crime is geo-coded using 2 years data and carried out cluster analysis and space statistical analysis through GIS space analysis by dividing 18 variables into social economy, urban space, crime prevention facility and crime occurrence index. The result of analysis shows cluster of 5 major crimes, theft, violence and sexual violence by Nearest Neighbor distance analysis and Ripley's K function. It also shows strong crime interconnectivity through criminal correlation analysis. In case of finding criminal cluster, you can find criminal hotspot. So, in this study I found concept of hotspot and considered technique about selection of hotspot. And then, selected hotspot about 5 major crimes, theft, violence and sexual violence through Nearest Neighbor Hierarchical Spatial Clustering.

• Journal of Wetlands Research
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• v.23 no.2
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• pp.122-132
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• 2021

We reviewed the methods employed in Korean tidal flat surveys to measure the local abundance of the endangered wildlife and marine protected species, the fiddler crab, Austruca lactea. A complete census for infinite population is impossible even in a limited habitat within a tidal flat, and density estimates from samples strongly vary due to diverse biological and ecological factors. The habitat boundaries and areas shift with periodicities or rhythmic activities of organisms as well as measurement errors. Hence the local abundance calculated from density and habitat areas should be regarded as transient. This conjecture was valid based on the spatio-temporal variations of the density averages, standard error ranges, and spatial distribution of the crab, A. lactea observed for 3 years (2015-2017) in Songdo tidal flat in Incheon. We proposed the potential habitat areas using the occurrence probability of 50% from logistic regression model, reflecting the importance of habitat conservation value as an alternative to local abundance. The spatial shape of potential habitat predicted from a generalized model would remain constant over time unless the species' critical environmental conditions change rapidly. The species-specific model is expected to be used for the introduction of desired species in future habitat restoration/creation projects.

• Journal of Food Hygiene and Safety
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• v.38 no.3
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• pp.99-111
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• 2023

The purpose of this study was to provide basic data for setting more detailed standards for baby food and to provide food information that can be used in real-world settings. We purchased 80 snacks and 40 drinks for infants and toddlers from supermarkets and online markets and analyzed tar color, artificial sweeteners, mycotoxins, and nutritional components (e.g., sucrose, sodium, and calcium). Fortunately, it was confirmed that both tar color and sodium saccharin, which do not have detection criteria for labeled foods for infants and toddlers, were not detected. However, acesulfame potassium was detected at 0.07 g/kg in one snack sample. As for myxotoxins, aflatoxin (B1, B2, G1, and G2) and ochratoxin A were not detected. Fumonisin B1, fumonisin B2, and zearalenone were detected in the ranges of 9.78-78.94 ㎍/kg, 5.58-11.73 ㎍/kg, and 2.96-8.83 ㎍/kg, respectively, but only in snacks. Sucrose was detected in 65 of the snacks (0.02-40.94 g/net weight [g]) and in 24 of the drinks (0.12-27.60 g/net weight [g]). Minerals were detected in most of the samples, and in four snacks, the zinc content per net exceeded the tolerable upper intake level for infants. Sixteen snacks exceeded the food standards for sodium content for infants and toddlers, but none of them were labeled as food for infants and toddlers in the product manufacturing report, such that the corresponding standards could not be applied. Therefore, it seems necessary to establish institutional improvements, such as strengthening labeling standards, so that the currently enforced standards can be appropriately applied, and establishing standards for labeled foods for infants and toddlers.