The high radon (Rn222) potentials of soil, groundwater, hotspring and indoor environments in the Taejon city area were delineated by use of an EDA RDA-200 radon detector. The U and Th contents were also analysed using a Multi Channel Analyzer to illustrate the sources of the radon potentials. The average U concentrations in Taejon vary according to the type of granites such as 4.14±2.36ppm in schistose granite (SG), 3.13±1.70ppm in biotite granite (BG) and 3.01±1.95ppm in two mica granite (TG). The U contents in the granites are closely related with the amounts of uraniferous minerals. However, the U contents in the soil are found to be 5.05±4.75ppm in TG, 4.07±1.69ppm in BG and 3.87±1.91ppm in SG which are mainly explained by the different cation exchange capacities (CEC) of the soils from various granites. The levels of soil radon are 552±656pCi/l in SG, in which levels at two locations exceed the level of 1,350 pCi/l established as guideline for follow-up action by the U.S. Environmental Protection Agency (EPA), 443±284pCi/l in TG and 224±115pCi/l in the BG. The soil radon concentrations are found to be proportional to the U content and hardness of the soils. The groundwater radon concentrations in the domestic wells of - 30~-100 m depth show that 6,907±4,665pCi/l in TG, 5,503±6,551pCi/l in SG and 2,104±1,157pCi/l in BG which are positively related with U contents in soils. The radon levels of six groundwater wells in TG and two in SG are greater than guideline for drinking water level, 10,000 pCi/l by EPA (1986). Average radon contents of hotsprings and public bathes in the TG area are 7,071±1,942pCi/l and 1,638±709pCi/l, respectively, which are below the EPA standard for remedial action value of the 10,000 pCi/l. The mean indoor radon concentrations of the TG and SG areas are 1.60±1.20pCi/l and 1.60±0.70pCi/l, respectively. The elevated indoor radon levels of 5.6 pCi/l and 6.7 pCi/l are found to be particularly in TG area, which exceeds 4 pCi/i guideline, correlating positively with the U contents in the soil and radon concentration in the groundwater.
This study aims to reveal the direction of municipal ordinances for smart cities, while focusing on 74 municipal ordinances from 72 municipal governments through topic modeling. As a result, the main keywords that show a high frequency belong to establishment and operations of the Smart City Committee. From the result of topic modeling Latent Dirichlet Allocation(LDA), it classifies municipal ordinances for smart cities into eight topics as follows: Topic 1(security for process of smart cities), Topic 2(promotion of smart city industry), Topic 3(composition of a smart city consultative body for local residents), Topic 4(support system for smart cities), Topic 5(management for personal information), Topic 6(use of smart city data), Topic 7(implementation for intelligent public administration), and Topic 8(smart city promotion). As for topic categorization by region, Topics 5, 6, and 8 which are mostly related to the practical operation of smart cities have a significant portion of municipal ordinances for smart cities in the Seoul metropolitan area. Then, Topics 2, 3, and 4 which are mostly related to the initial implementation of smart cities have a significant portion of municipal ordinances for smart cities in provincial areas.
Journal of the Korean Association of Geographic Information Studies
/
v.17
no.4
/
pp.101-111
/
2014
Spatial events are predictable using data mining classification algorithms. Decision trees have been used as one of representative classification algorithms. And they were normally used in the classification tasks that have label class values. However since using rule ranking methods, spatial prediction have been applied in the spatial prediction problems. This paper compared rule ranking methods for the spatial prediction application using a decision tree. For the comparison experiment, C4.5 decision tree algorithm, and rule ranking methods such as Laplace, M-estimate and m-branch were implemented. As a spatial prediction case study, landslide which is one of representative spatial event occurs in the natural environment was applied. Among the rule ranking methods, in the results of accuracy evaluation, m-branch showed the better accuracy than other methods. However in case of m-brach and M-estimate required additional time-consuming procedure for searching optimal parameter values. Thus according to the application areas, the methods can be selectively used. The spatial prediction using a decision tree can be used not only for spatial predictions, but also for causal analysis in the specific event occurrence location.
Journal of Korean Library and Information Science Society
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v.51
no.3
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pp.103-121
/
2020
This study aimed to analyze the research trends of school libraries from 1990 to July 2020. To this end, LDA topic modeling analysis was conducted to the domestic article abstracts related to school libraries. The total number of documents is 498 papers published by the four major domestic journals in Library and Information Science. The log-likelihood estimate criterion was used to determine the number of topics for topic modeling. As a result of the study, 27 topics were discovered, then, theory were categorized by eight subject areas: general, institutional system, building/equipment, operation/management, data organization, service, education, and others. The most popular research was library utilization classes (T27) and Information Utilization (T2). More than 20 studies were found in each evaluation index development (T13), school librarian placement (T24), learning information media utilization (T3), community public library (T7), library cooperation (T9), library use (T17), library research (T11), reading education (T4), collection development (T5), and education effects/teaching methods (T18).
This study was conducted to assess the geochemical contamination degree of As, Cd, Cu, Pb, Sb, and Zn in the soil and water samples from an abandoned gold mine. Enrichment Factor (EF), Geoaccumulation Index (Igeo), and Pollution Load Index (PLI) were carried out to assess the geochemical contamination degree of the soil samples. Variations of sulfate and heavy metals concentration in water samples were determined to identify the geochemical distribution with respect to the distance from the mine tailing dam. Geochemical pollution indices indicated significant contaminated with As, Cd, Pb, and Zn in the soil samples that areas close to the mine tailing dam, while, Sb showed similar indices in all soil samples. These results indicated that the As, Cd, Pb, and Zn dispersion has occurred via anthropogenic sources, such as mining activities. In terms of water samples, anomalies in the concentrations of As, Cd, Zn, and SO42- was determined at specific area, in addition, the concentrations of the elements gradually decreased with distance. This result implies the heavy metals distribution in water has carried out by the weathering of sulfide minerals in the mine tailing and soil. The study area has been conducted the remediation of contaminated soil in the past, however, the geochemical dispersion of heavy metals was supposed to be occurred from the potential contamination source. Therefore, continuous monitoring of the soil and water is necessary after the completion of remediation.
Despite the common use of 2D electrical resistivity surveys to investigate active faults buried under Quaternary sediments in Korea, interpretation of the geological characteristics of these faults from resistivity distributions often relies on subjective experience. This reliance on subjective interpretations can lead to inconsistencies and inaccuracies. Therefore, a more systematic and objective approach is required to enhance the reliability and accuracy of geological interpretations. In this study, 2D and 3D electrical resistivity surveys were conducted on two active faults, in the southern Yangsan Fault and the northeastern part of the Gongju Fault, both of which are covered by Quaternary sediments. The relationship between the geological characteristics of the active fault zone and the electrical resistivity was examined, based on the resistivity distribution within the strata. As a result, this study found that the 2D electrical resistivity distribution pattern takes on a vertical form when different rock types are distributed on either side of the fault plane boundary, or when a fracture zone caused by seismic activity is developed on one side of the fault plane within the same rock type. The active fault plane is located at the boundary between areas of relatively high and low resistivity. In addition, because faults exhibit the geological characteristic of being a linear structure, it was found that the 3D electrical resistivity distribution is useful for understanding the spatial distribution of fracture zones. However, because 3D surveys require considerable effort in both fieldwork and interpretation, their application in domestic active fault investigations has been limited. Therefore, the introduction and further development of 3D exploration technology are required in the future.
Recently, heavy metals contamination of the agricultural soil and crops surrounding mining areas has been identified as one of the most serious environmental problems in South Korea. The Ministry of the Environment in Korea conducted a Preliminary National Environmental Health Survey (PNEHS) in abandoned metal mines in 2007. The priority for a subsequent detailed examination was ranked from the results of PNEHS. The studied mine which was ranked as being of the highest priority is located in the midwestern part of Korea and was operated from 1911 to 1985. In this study, the contamination levels of the heavy metals in the abandoned metal mine were investigated. From the results, the average daily dose (ADD), target hazard quotient (THQ) and target cancer risk of the heavy metals were evaluated. The concentration of arsenic (As) in all of the tailings from the mine was higher than its countermeasure standard of Korea. In particular, the highest concentration of As, 330 mg/kg, was up to 15 times higher than its countermeasure standard. The average concentration of As in agricultural soils was higher than the warning standard of Korea, and higher than its countermeasure standard at six sites. The average concentrations of the analyzed heavy metals in agricultural soil were below the warning standard, but concentrations of cadmium (Cd) and lead (Pb) at 4 sites were higher than its warning standard. The average concentration of As in surface water exceeded the warning standard of Korea. The value of the THQ of As for the tailings was higher than the health protection standard 1. The value of THQ of As for the farmlands was lower than the standard, while the hazard index (HI) of As was higher than the standard. The value of target cancer risk (TCR) of As, 6.44×10−4, were higher than the health protection standard of a lifetime risk for TCR at 1×10−6. This suggests that the residents around the metal mines are exposed to As pollution with a carcinogenic risk.
Heavy metals are extracted from stream sediments, roadside soils and sediments and soils and tailings from mining area using partial extraction, acid digestion and HF-digestion. Compared to amounts of heavy metals extracted using partial extraction, those extracted using acid digestion are higher by 2.0∼221 times in Cu, 2.4∼2806 times in Pb, 1.3∼121 times in Cd, 14. 1∼1300885 times in Fe, 1.2∼272 times in Mn, 1.3∼373 times in Zn, 2.2∼1735 times in Cr. There is no special relationship between the extracted amounts of heavy metals using partial extraction and those using acid digestion. However, it is possible that there is a certain relationship between those using acid digestion and those using HF-digestion. Although partial extraction, which extracts less amounts of heavy metals (Cd, Cu, Pb) from soil compared to acid digestion, is used in domestic standard method for examination of soil, domestic soil standard for heavy metals in non-agricultural and industrial areas is higher than soil standard in foreign countries which use acid digestion. For improvement of the domestic standard method for assessment of soil, it is suggested to lower the domestic soil standard for heavy metals or to change pretreatment method for extracting heavy metals from partial extraction to acid digestion with modifying the soil standard.
Environmental problems typically occurring in abandoned mine lands (AML) include: contaminated and acidic surface water and groundwater; stockpiled waste rock and mill tailings; and ground subsidences due to mining operations. This study examines the effectiveness of various geophysical techniques for mapping potential hazard and contaminated zones. Four AML sites with sedimentation contamination problems, acid mine drainage (AMD) channels, ground subsidence, manmade liner leakage, and buried mine tailings, were selected to examine the applicability of various geophysical methods to the identification of the different types of mine hazards. Geophysical results were correlated to borehole data (core samples, well logs, tomographic profiles, etc.) and water sample data (pH, electrical conductivity (EC), and heavy metal contents). Zones of low electrical resistivity (ER) corresponded to areas contaminated by heavy metals, especially contamination by Cu, Pb, and Zn. The main pathways of AMD leachate were successfully mapped using ER methods (low anomaly peaks), self-potential (SP) curves (negative peaks), and ground penetrating radar (GPR) at shallow penetration depths. Mine cavities were well located based on composite interpretations of ER, seismic tomography, and well-log records; mine cavity locations were also observed in drill core data and using borehole image processing systems (BIPS). Damaged zones in buried manmade liners (used to block descending leachate) were precisely detected by ER mapping, and buried rock waste and tailings piles were characterized by low-velocity zones in seismic refraction data and high-resistivity zones in the ER data.
In June 2016, the term "Fourth Industrial Revolution" was first used at the World Economic Forum in Davos, Switzerland, and it gained worldwide attention. Consequently, the importance of smart ports has increased as the shipping industry has been incorporating various Fourth Industrial Revolution technologies. Currently, major countries around the world are working to achieve digital transformation in the maritime and port industry by establishing comprehensive smart ports. However, the smartification of domestic ports in South Korea is currently limited to a few areas such as Busan, Incheon, and Gwangyang, focusing on port automation. In this context, this study performed keyword analysis to identify key components of smart ports and conducted Analytic Hierarchy Process (AHP) analysis among relevant stakeholders to determine the priorities for the Introduction of smart ports in South Korea. The analysis revealed that universities prioritized automation, intelligenceization, informatization and environmentalization in that order. Research institutes prioritized informatization, intelligenceization, automation and environmentalization. Government agencies prioritized informatization, automation, intelligenceization and environmentalization, while private sector enterprises prioritized automation, intelligenceization, informatization, and environmentalization.
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