• Economic and Environmental Geology
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• v.42 no.3
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• pp.235-246
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• 2009

High-saline ground water, whose eclectrical conductivity value ranges from 12,000 to 21,000 $\mu$S/cm, occurs at the small catchment of Gilsan stream near Geum-river estuary dike. These high-saline ground water comes form three different aquifers consisting of two horizons of sand sediments and one weathered zone with top part of unconformity. For these three aquifers showing mutual independence in terms of hydrogeological and hydrogeochemical connection, we examined characteristics of aqifer occurrences and their water chemistry, and observed and analyzed the fluctuations of the ground water level and electrical conductivity. Our study results indicate that the high-saline characteristics of ground water in this study area should not come from dynamic recent seawater intrusion, but might be due to the fossil saline water included and isolated within the paleo-sediments or weathered zone and their upper unconformity part. This high-saline water seems to be now partially mixed and affected by freshwater in the higher inland reach of Gilsan stream.

• Korean Journal of Ecology and Environment
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• v.38 no.2 s.112
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• pp.160-180
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• 2005

Long-term data (Ministry of Environment Water Quality Monitoring data) of phytoplankton biomass (chlorophyll a) and water quality were analyzed to investigate trends in biomass of the primary producers and water quality for the estuarine systems in Korea: Sumjin River, Han River, Asan Lake- Bay, Youngsan River, Keum River and Nakdong River. The literatures were also reviewed to examine the characteristics of phytoplankton biomass and water quality in the estuarine systems. The Sumjin River estuary, the single estuary without a dike in Korea showed the characteristics similar to other typical estuarine systems. Phytoplankton biomass was high during the fall at transitional regions (5 ${\sim}$ 15 psu) after riverine freshwater inputs were increased in summer. Concentrations of the nitrate and silicate were increased with the high river discharge rates. Phytoplankton biomass and nutrient concentrations were high during spring at the lower regions in the Han River whereas phytoplankton biomass and nutrient concentrations were high during spring at the upper regions in the Youngsan River. Phytoplankton biomass was the highest in the Asan Lake and nutrient concentrations were high at the upper region of the lake. In Nakdong River, phytoplankton biomass was high during winter and the biomass was slightly higher at upper region than at lower region. Long-term trends showed that total nitrogen and total phosphorus were mostly increased in the river systems. Implications of these results relevant to the water quality management for the river systems were also discussed.

• Korean Journal of Ecology and Environment
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• v.53 no.1
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• pp.63-72
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• 2020

In this study, to discuss on the applicability of eDNA as a new method to investigate fish diversity at streams, we applied eDNA at 4 streams (Geum River, Ji Stream, Hwangji Stream, Seomjin River), where endangered species are inhabits, with conventional survey (cast net and kick net). The average (±standard deviation) number of species investigated by eDNA were 19 species (±4.4), and it was relatively higher than average of conventional survey, 10 species (±4.8). Most of case, in this study, eDNA was more efficient than conventional survey. However, there were errors on species identification of Korean endemic species and aliied species from eDNA, and it seems the universal primer (MiFish primer set) is not suitable for them. Furthermore, some of endangered species, caught by conventional method, was not detected by eDNA. As the present universal primer is not suitable for identify the every freshwater fish species in Korea, the complementing or development of universal primer is needed, and the eDNA application after species specific marker development for detecting specific species like endangered species should be considered. In conclusion, if the manual for field survey method by eDNA is developed, we expect applicability enlargement for water ecosystem survey.

• Korean Journal of Environment and Ecology
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• v.32 no.2
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• pp.176-184
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• 2018

This study was intended to provide basic data for more ecological and systematic preservation and management planning of forest vegetations in the Baekdudaegan sector between Danmoknyeong and Guryongnyeong where biodiversity is considered to be very important. A vegetation survey using the Zurich-Montpellier (Z.-M.) method of phytosociology was carried out in a total 142 sites to examine the environmental characteristics. The survey showed the forest vegetation types of one community group, two communities, four groups, and four subgroups. Quercus mongolica and Acer pseudosieboldianum, which fall under Constancy Class V, were dominant species and deemed to be the key species of the forest ecosystem management plan for the investigated areas. Regarding species diversity, it was found that the dominant species of the VT3 type were evenly distributed in the area while the species of the VT4 type showed not only a diverse composition but also the most abundant number of species. Moreover, there were 24 of rare plants found in the Danmoknyeong-Guryongnyeong section: the critically endangered species include Dracocephalum rupestre; the endangered species include Saxifraga octopetala; the vulnerable species include Paeonia japonica, Euphorbia fauriei, Hanabusaya asiatica, and Parasenecio pseudotaimingasa; the least concern species include Aristolochia manshuriensis, Rodgersia podophylla, Salvia chanryoenica, Scopolia japonica, and Parasenecio firmus.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.1
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• pp.15-19
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• 2013

This study was carried out to establish the optimum organic fertilization and microbial compost on wheat cultivation in order to reduce the use of chemical fertilizers and improve the quality of wheat. The tests resulted in a yield of organic fertilization of 2~6% lower than the yield of standard 4.16 Ton/ha (a yield more than that of microbial compost). The recession was not statistically significant. The trial which involved organic fertilizer that had a yield of 800 kg/ha and microbial compost which had a yield of 2,000 kg/ha resulted in 96% yield of standard trial. The quality of flour in the manure was 50% less during the trial and was not making a good result. In protein content and SDS-sedimentation volume, standard trial had the highest yield in test trial (standard > miccompost > organic fertilization). However, Ash content was not statistically significant.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.413-413
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• 2019

하천과 호수에서 남조류의 이상 과잉증식 문제(이하 녹조문제)는 담수생태계의 생물다양성을 감소시키며, 음용수의 이취미 원인물질을 발생시켜 물 이용에 장해가 된다. 또한 독소를 생산하는 유해남조류가 대량 증식할 경우에는 가축이나 인간의 건강에 치명적 해를 끼치기도 한다. 그 동안 국내에서 녹조문제는 댐 저수지와 하구호와 같은 정체수역에서 간헐적으로 문제를 일으켰으나, 4대강사업(2010-2011)으로 16개의 보가 설치된 이후 낙동강, 금강, 영산강 등 대하천에서도 광범위하게 발생되고 있어 중요한 사회적 환경적 이슈로 대두되었다. 한편, 대하천에 설치된 보 구간에서 빈번히 발생하는 녹조현상의 원인에 대해서는 전 지구적 기온상승에 따른 기후변화의 영향이라는 주장과 유역으로부터 영양염류의 과도한 유입, 가뭄에 따른 유량감소, 보 설치에 따른 체류시간 증가 등 다양한 의견이 제시되고 있으나, 대상 유역과 수체의 특성에 따라 녹조 발생의 원인이 상이하거나 또는 다양한 요인이 복합적으로 작용하기 때문에 보편적 해석(universal interpretation)이 어려운 것이 현실이다. 따라서 각 수계별, 보별 녹조현상에 대한 정확한 원인분석과 효과적인 대책 마련을 위해서는 집중된 실험자료와 데이터마이닝 기법에 근거로 한 보다 과학적이고 객관적인 접근이 이루어져야 한다. 본 연구에서는 2012년 보 설치 이후 남조류에 의한 녹조현상이 빈번히 발생하고 있는 낙동강 4개보(강정고령보, 달성보, 합천창녕보, 창녕함안보)를 대상으로 집중적인 현장조사와 실험분석을 수행하고, 수집된 기상, 수문, 수질, 조류 자료에 대해 통계분석과 다양한 데이터모델링 기법을 적용하여 보별 남조류 우점 환경조건과 이를 제어하기 위한 주요 조절변수를 규명하는데 있다. 연구대상 보 별 수질과 식물플랑크톤의 정성 및 정량 실험은 2017년 5월부터 2018년 11월까지 2년에 걸쳐 실시하였으며, 남조류 세포수 밀도와 환경요인과의 상관성 분석을 실시하고, 단계적 다중회귀모델(Step-wise Multiple Linear Regressions, SMLR), 랜덤포레스트(Random Forests, RF) 모델과 재귀적 변수 제거 기법(Recursive Feature Elimination using Random Forest, RFE-RF)을 이용한 변수중요도 평가, 의사결정나무(Decision Tree, DT), 주성분분석(Principal Component Analysis, PCA) 기법 등 다양한 모수적 및 비모수적 데이터마이닝 결과를 바탕으로 각 보별 남 조류 우점 환경요인을 종합적으로 해석하였다.

• Korean Journal of Heritage: History & Science
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• v.42 no.1
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• pp.62-70
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• 2009

The study was conducted from Jan. 11 to Jan. 12 2008 on 17 areas which were the wintering area of Aegypius monachus and where the birds were observed. In the study, a total of 1,912 individuals were observed to winter in the areas, which was larger than any previous observation. The study found that 1,500 individuals wintered in the central region of Korea including Gyeonggido and Kangwondo, which accounted for 78.45%, and 412 individuals (21.55%) in the southern region such as Gyeongbuk, Gyeongnam, Jeannam and Jejudo (Island). Given the number of individuals wintering by region, Jangdan Peninsula (777 individuals), Cheorwon (488 individuals) and Sancheonggun(193 individuals) were mostly found. In comparison with the previous studies, 20-30% of the individuals have moved south since 2006. This movement might be attributed to the suspension of feeding campaigns, but the birds still crowded some specific areas.

• Journal of Korea Water Resources Association
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• v.54 no.7
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• pp.453-462
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• 2021

As the frequency of localized heavy rainfall has increased during recent years, the importance of high-resolution radar data has also increased. This study aims to correct the bias of Dual Polarization radar that still has a spatial and temporal bias. In many studies, various statistical techniques have been attempted to correct the bias of radar rainfall. In this study, the bias correction of the S-band Dual Polarization radar used in flood forecasting of ME was implemented by a Convolutional Autoencoder (CAE) algorithm, which is a type of Convolutional Neural Network (CNN). The CAE model was trained based on radar data sets that have a 10-min temporal resolution for the July 2017 flood event in Cheongju. The results showed that the newly developed CAE model provided improved simulation results in time and space by reducing the bias of raw radar rainfall. Therefore, the CAE model, which learns the spatial relationship between each adjacent grid, can be used for real-time updates of grid-based climate data generated by radar and satellites.

• Ecology and Resilient Infrastructure
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• v.10 no.1
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• pp.11-19
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• 2023

Alien species are known to threaten regional biodiversity globally, which has increased global interest regarding introduction of alien species. The Ministry of Environment of Korea designated species that have not yet been introduced into the country with potential threat as alert alien species to prevent damage to the ecosystem. In this study, potential habitats of Esox lucius and Maccullochella peelii, which are predatory and designated as alert alien fish, were predicted on a national basis. Habitat suitability was evaluated using EHSM (Ecological Habitat Suitability Model), and water temperature data were input to calculate Physiological Habitat Suitability (PHS). The prediction results have shown that PHS of the two fishes were mainly controlled by heat or cold stress, which resulted in biased habitat distribution. E. lucius was predicted to prefer the basins at high latitudes (Han and Geum River), while M. peelii preferred metropolitan areas. Through these differences, it was expected that the invasion pattern of each alien fish can be different due to thermal preference. Further studies are required to enhance the model's predictive power, and future predictions under climate change scenarios are required to aid establishing sustainable management plans.

• Korean Journal of Ichthyology
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• v.34 no.3
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• pp.208-217
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• 2022

We wanted to develop a real-time PCR assay capable of detecting Liobagrus obesus in environmental DNA (eDNA) extracted from freshwater samples using a pair of species-specific primers and probe for the endangered fish, L. obesus. The species-specific primers and probe were designed in consideration of single nucleotide polymorphisms between 65 species of freshwater fish living in the Republic of Korea within the cytochrome b (cytb) gene of mitochondrial DNA. The species-specific primers and probe, in the real-time PCR assay, showed high specificity as only the L. obesus genomic DNA (gDNA) was found to be positive in the specificity verification using 65 species gDNA of freshwater fish in the Republic of Korea. In addition, in the detection limit analysis using the serial dilution concentrations of L. obesus gDNA, it was found that it was possible to detect up to 0.2 pg, showing high sensitivity. Afterwards, using the species-specific primers and probe, real-time PCR assay was performed on freshwater samples obtained from 8 stations in the mid-upper basin of Geum River. As a result, the cytb gene of L. obesus was detected in total 5 stations including all 3 stations where this species was collected at the time of field survey. Therefore, the species-specific primers and probe developed in present study, and the real-time PCR assay using them, can accurately detect the cytb gene of L. obesus from eDNA samples, which can be utilized to monitor the existing habitats of this species and to discover potential new habitats.