• Animal Systematics, Evolution and Diversity
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• 제30권4호
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• pp.240-247
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• 2014

Tubificid oligochaetes are common and frequently dominant in freshwater benthic habitats. They are so tolerant to water pollution that they are often used as biological indicators. Faunistic studies of Korean freshwater oligochaetes have been actively conducted recently. The most well studied oligochaete family in Korea is the tubificids following the naidids. Nine species of tubificids have been reported so far. Nevertheless, many species of tubificids still remain to be discovered in Korea. In this study, we added four species of tubificid oligochaetes to the Korean fauna, including Linmodrilus profundicola (Verrill, 1871), Potamothrix heuscheri (Bretscher, 1900), Tubifex blanchardi $Vejdovsk\acute{y}$, 1891, and Ilyodrilus templetoni (Southern, 1909) based on specimens collected from three locations in Korea: Cheonan-si, Geoje-si, and Seocheon-gun. In particular, P. heuscheri was first reported in Asia.

• 한국지하수토양환경학회지:지하수토양환경
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• 제7권1호
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• pp.63-77
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• 2002

Salinization is an important environmental problem encountered in coastal aquifers. In order to evaluate the salinization problem in the western coastal area of Korea, we have performed a regional hydrochemical study on shallow well groundwaters (N=229) collected within 10 km away from the coastline. The concentrations of analyzed solutes are very wide in range, suggesting that the hydrochemistry is controlled by several processes such as water-rock interaction, seawater mixing, and anthropogenic contamination. Based on the graphical interpretation of cumulative frequency curves for some hydrochemical parameters (esp., $Cl^{-}$ and ${NO_3}^-$), the collected water samples were grouped into two major populations (1) a background population whose chemistry is predominantly affected by water-rock interaction, and (2) an anomalous population which records the potential influences by either seawater mixing or anthropogenic pollution. The threshold values obtained are 34.7 mg/l for $Cl^{-}$ and 37.2 mg/l for ${NO_3}^-$, Using these two constituents, groundwaters were further grouped into four water types as follows (the numbers in parenthesis indicate the percentage of each type water) : (1) type 1 waters (38%) that are relatively poor in $Cl^{-}$ and ${NO_3}^-$, which may represent their relatively little contamination due to seawater mixing and anthropogenic pollution; (2) type 2 waters (21%) which are enriched in $Cl^{-}$, Indicating the considerable influence by seawater mixing; (3) ${NO_3}^-$-rich, type 3 waters (11%) which record significant anthropogenic pollution; and (4) type 4 waters (30%) enriched in both $Cl^{-}$ and ${NO_3}^-$, reflecting the effects of both seawater mixing and anthropogenic contamination. The results of the water type classification correspond well with the grouping on a Piper's diagram. On a Br x $10^4$versus Cl molar ratio diagram, most of type 2 waters are also plotted along or near the seawater mixing line. The discriminant analysis of hydrochemical data also shows that the classification of waters into four types are so realistic to adequately reflect the major process(es) proposed for the hydrochemical evolution of each water type. As a tool for evaluating the degree of seawater mixing, we propose a parameter called 'Seawater Mixing Index (S.M.I.)’ which is based on the concentrations of Na, Mg, Cl, and $SO_4$. All the type 1 and 3 waters have the S.M.I. values smaller than one, while type 2 and type 4 waters mostly have the values greater than 1. In the western coastal area of Korea, more than 21% of shallow groundwaters appear to be more or less affected by salinization process.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권2호
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• pp.767-785
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• 2021

With the rapid development of information technology, it is now possible to analyze the spatial patterns of cultivated land and its evolution by combining GIS, geostatistical analysis models and spatiotemporal big data for the dynamic monitoring and management of cultivated land resources. The spatial pattern of cultivated land and its evolutionary patterns in Luoyang City, China from 2009 to 2019 were analyzed using spatial autocorrelation and spatial autoregressive models on the basis of GIS technology. It was found that: (1) the area of cultivated land in Luoyang decreased then increased between 2009 and 2019, with an overall increase of 0.43% in 2019 compared to 2009, with cultivated land being dominant in the overall landscape of Luoyang; (2) cultivated land holdings in Luoyang are highly spatially autocorrelated, with the 'high-high'-type area being concentrated in the border area directly north and northeast of Luoyang, while the 'low-low'-type area is concentrated in the south and in the municipal area of Luoyang, and being heavily influenced by topography and urbanization. The expansion determined during the study period mainly took place in the Luoyang City, with most of it being transferred from the 'high-low'-type area; (3) elevation, slope and industrial output values from analysis of the bivariate spatial autocorrelation and spatial autoregressive models of the drivers all had significant effects on the amount of cultivated land holdings, with elevation having a positive effect, and slope and industrial output having a negative effect.

• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1476-1484
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• 2023

Laboratory experiments and point monitoring of reservoir sediments have proven that stable sulfate reduction (SSR) can lower the concentrations of toxic metals and sulfate in acidic groundwater for a long time. Here, we hypothesize that SSR occurred during in situ leaching after uranium mining, which can impact the fate of acid groundwater in an entire region. To test this, we applied a sulfur isotope fractionation method to analyze the mechanism for natural attenuation of contaminated groundwater produced by acid in situ leaching of uranium (Xinjiang, China). The results showed that δ³⁴S increased over time after the cessation of uranium mining, and natural attenuation caused considerable, area-scale immobilization of sulfur corresponding to retention levels of 5.3%-48.3% while simultaneously decreasing the concentration of uranium. Isotopic evidence for SSR in the area, together with evidence for changes of pollutant concentrations, suggest that area-scale SSR is most likely also important at other acid mining sites for uranium, where retention of acid groundwater may be strengthened through natural attenuation. To recapitulate, the sulfur isotope fractionation method constitutes a relatively accurate tool for quantification of spatiotemporal trends for groundwater during migration and transformation resulting from acid in situ leaching of uranium in northern China.

• Asian Journal of Atmospheric Environment
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• 제12권2호
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• pp.165-177
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• 2018

Particulate matter (PM) measurements are important in air quality, public health, epidemiological studies and decision making for short and long-term policies implementation. However, only few cities in the word have advance air quality-monitoring networks able to provide reliable information of PM leaves in the ambient air, trends and extent of the pollution. In Colombia, only major cities measure PM concentrations. Available measurements from Bogota, Medellin and Bucaramanga show that PM concentration are well above World Health Organization guidelines, but up to now levels and trends of PM in other cities and regions of the country are not well known. Satellite measurements serve as an alternative approach to study air quality in regions were surface measurements are not available. The aim of this study is to perform a spatial and temporal assessment of PM in the ambient air of Colombia. We used Aerosol optical depth (AOD) retrieved by the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite of NASA and surface measurements from the air quality networks of Bogota, Medellin and Bucaramanga. In a first step, we estimated the correlation between MODIS-AOD and monthly average surface measurements (2000 to 2015) from these three cities, obtaining correlation coefficient R values over 0.4 for the cities under study. After, we used AOD and $PM_{10}$ measurements to study the temporal evolution of PM in different cities and regions. Finally, we used AOD measurements to identify cities and regions with the highest AOD levels in Colombia. All the methods presented in this paper may serve as an example for other countries or regions to identify and prioritize locations that require the implementation of more accurate air quality measurements.

• 인터넷정보학회논문지
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• 제12권1호
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• pp.85-98
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• 2011

최근, 세계적으로 에너지 소비 증가와 온난화 현상의 진행으로 정치, 경제, 사회 및 환경 부분에 직접적인 영향을 받는 글로벌 환경위기에 직면하고 있다. 이러한 문제를 해결하기 위해 세계 각 국에서는 그린 ICT 정책을 마련하고 있다. 국내에서도 환경 오염 문제를 해결하고, 에너지 효율을 높일 수 있는 그린 ICT 정책 도입을 통한 대책을 마련해야 한다. 따라서 본 연구의 목적은 국내 그린 ICT 정책 도입 후 효율을 최대화 하기 위해 고려해야 할 정책 목표의 우선순위를 전략적으로 도출하는 것이다. 이를 위해 '저탄소 녹색성장 기본법'을 바탕으로 경제성, 효율성, 환경성, 기술성, 안정성 등의 주요 변수를 도출하였고, 각각의 변수 별 세부 변수를 도출하였다. 도출된 변수들의 우선순위 분석을 위해 관련 정책 전문가를 대상으로 AHP 방법과 ANP 방법으로 각각 설문조사를 실시하였다. 설문 결과와 AHP 방법론으로 그린 ICT 정책의 우선순위를 도출한 결과 환경성, 기술성, 경제성, 효율성, 안정성의 순으로 도출되었고, ANP 방법론으로 결과를 도출한 결과 기술성, 효율성, 경제성, 환경성, 안정성의 순으로 도출되었다. 이와 같이 본 논문은 AHP와 ANP 방법론을 이용하여 그린 ICT 정책 목표의 우선순위를 학술적으로 분석하였다. 따라서 향후 관련 정책 수립 시 실용적인 가이드라인이 될 수 있다.

• 한국분말재료학회지
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• 제29권5호
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• pp.411-417
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• 2022

Environmental issues such as global warming due to fossil fuel use are now major worldwide concerns, and interest in renewable and clean energy is growing. Of the various types of renewable energy, green hydrogen energy has recently attracted attention because of its eco-friendly and high-energy density. Electrochemical water splitting is considered a pollution-free means of producing clean hydrogen and oxygen and in large quantities. The development of non-noble electrocatalysts with low cost and high performance in water splitting has also attracted considerable attention. In this study, we successfully synthesized a NiCo₂O₄/NF electrode for an oxygen evolution reaction in alkaline water splitting using a hydrothermal method, which was followed by post-heat treatment. The effects of heat treatment on the electrochemical performance of the electrodes were evaluated under different heat-treatment conditions. The optimized NCO/NF-300 electrode showed an overpotential of 416 mV at a high current density of 50 mA/cm² and a low Tafel slope (49.06 mV dec^-1). It also showed excellent stability (due to the large surface area) and the lowest charge transfer resistance (12.59 Ω). The results suggested that our noble-metal free electrodes have great potential for use in developing alkaline electrolysis systems.

• Animal Systematics, Evolution and Diversity
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• 제33권3호
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• pp.169-175
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• 2017

In the northwestern Pacific region, the pen shell (Atrina pectinata) is a widely distributed bivalve and economically important in fisheries. Recently, stock of this species has been greatly reduced due to overexploitation and marine pollution, which arouses interest in conservation. Studies on genetic and taxonomic entities of pen shells have not been tried in Korea, which makes difficult to take measures for effective conservation of this marine resource. In this study, we investigated mitochondrial genetic polymorphism of pen shells collected from 4 locations in Korea and Japan using cytochrome c oxidase I (COI) gene sequences. A total of 39 haplotypes were identified among 86 individuals of pen shell. Although only 5 haplotypes were shared, no significant genetic differentiation was observed between Korean and Japanese populations. These results suggest that pen shell populations of these regions share an ancestral population which might have experienced expansion during the Pleistocene, but gene flow must have been highly restricted after expansion.

• 천문학회지
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• 제37권5호
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• pp.517-525
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• 2004

We present an update on our proposal that during the 'quasar era' (1.5 $\le$ z $\le$ 3), powerful radio galaxies could have played a major role in the enhanced global star-formation, and in the widespread magnetization and metal pollution of the universe. A key ingredient of this proposal is our estimate that the true cosmological evolution of the radio galaxy population is likely to be even steeper than what has been inferred from flux-limited samples of radio sources with redshift data, when an allowance is made for the inverse Compton losses on the cosmic microwave background which were much greater at higher redshifts. We thus estimate that a large fraction of the clumps of proto-galactic material within the cosmic web of filaments was probably impacted by the expanding lobes of radio galaxies during the quasar era. Some recently published observational evidence and simulations which provide support for this picture are pointed out. We also show that the inverse Compton x-ray emission from the population of radio galaxies during the quasar era, which we inferred to be largely missing from the derived radio luminosity function, is still only a small fraction of the observed soft x-ray background (XRB) and hence the limit imposed on this scenario by the XRB is not violated.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2004년도 추계 종합학술대회 논문집
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• pp.36-42
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• 2004

근대 산업사회에서 현대 지식기반 사회에 이르러 문화에 대한 관심이 증가하고 있다. 중세의 신 중심 사상에서 인간 중심 사상으로의 중심이동은 이제 생명 복제와 같은 과학 기술 발달과 함께 인류가 신의 영역에 점차 가까워지는 단계에 이르게 되었다. 이러한 급진적인 변화의 흐름에서도 인류 문화의 진화는 더디게만 느껴진다. 생명 경시, 종교 전쟁, 환경 파괴, 적자생존의 자본주의 제도 등은 우리가 바라는 인류공영의 발목을 옥죄는 듯하다. 본 논문은 이러한 현대의 문화 개념과 정체성을 되짚어 보고 21세기라는 새로운 시대의 그릇에 담길만한 문화의 개념을 '물'의 특성을 가진 'SeaCricle'이라는 새로운 용어로 재정의해 보고자 한다.