• Parasites, Hosts and Diseases
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• v.59 no.3
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• pp.265-271
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• 2021

We surveyed on the infection status of zoonotic trematode metacercariae (ZTM) in freshwater fishes from Soyang-cheon (a branch stream of Mangyeong-gang) in Wanju-gun, Jeollabuk-do, the Republic of Korea. A total of 927 fishes were individually examined with the artificial digestion method during 2013-2015 (462 fish in 15 spp.) and 2018-2019 (465 fish in 25 spp.). Clonorchis sinensis metacercariae were detected in 207 (31.4%) out of 659 fishes in 14 positive fish species (PFS), and their mean intensity was 114 per fish infected (PFI). Metagonimus spp. metacercariae were found in 302 (37.4%) out of 808 fishes in 21 PFS, and their mean intensity was 12 PFI. Centrocestus armatus metacercariae were detected in 222 (59.0%) out of 376 fishes in 12 PFS, and their mean intensity was 383 PFI. Echinostoma spp. metacercariae were found in 139 (22.1%) out of 628 fishes in 10 PFS, and their mean intensity was 7 PFI. Clinostomum complanatum metacercariae were detected in 14 (6.5%) out of 214 fishes in 4 PFS, and their mean intensity was 2.4 PFI. Metorchis orientalis metacercariae were detected in 36 (13.5%) out of 267 fishes in 5 PFS, and their mean intensity was 4.3 PFI. Conclusively, the prevalence and infection intensity of ZTM is generally not so high in fishes from Soyang-cheon. However, those of C. sinensis metacercariae are more or less higher in 2 fish species, Pungtungia herzi and Sarcocheilichthys variegatus wakiyae.

• Journal of Korean Society on Water Environment
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• v.36 no.6
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• pp.489-499
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• 2020

Effective science-based management of the basin water resources requires an understanding of the characteristics of the streams, such as the baseflow discharge. In this study, the base flow was estimated in the two watersheds with the least artificial factors among the Nakdong River watersheds, as determined using the chemical hydrograph separation technique. The 16-year (2004-2019) discontinuous observed stream flow and electrical conductivity data in the Total Maximum Daily Load (TMDL) monitoring network were extended to continuous daily data using the TANK model and the 7-parameter log-linear model combined with the minimum variance unbiased estimator. The annual base flows at the upper Namgang Dam basin and the upper Nakdong River basin were both analyzed to be about 56% of the total annual flow. The monthly base flow ratio showed a high monthly deviation, as it was found to be higher than 0.9 in the dry season and about 0.46 in the rainy season. This is in line with the prevailing common sense notion that in winter, most of the stream flow is base flow, due to the characteristics of the dry season winter in Korea. It is expected that the chemical-based hydrological separation technique involving TANK and the 7-parameter log-linear models used in this study can help quantify the base flow required for systematic watershed water environment management.

• Korean Journal of Ecology and Environment
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• v.40 no.1
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• pp.103-109
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• 2007

To investigate the effects of artificial vegetation island (AVI) on fish distribution, we compared fish fauna from artificial vegetation island (AVI) area, which installed in 2000, natural vegetation area (NVA) and vegetation-free area (VFA) at Kyungan Stream area of Lake Paldang from Jul. to Nov., 2005. Results showed that 11 families 23 genera 24 fish species were distributed in the AVI and NVA. Squalidus japonicus coreanus, a small-size fish which generally lives at the downstream, dominated absolutely in the individual numbers. However, only 6 families 11 genera 12 species of fishes caught at the VFA, and dominant fishes were Hemibarbus labeo and Erythroculter erythropterus, a medium to large-size migratory fishes which live in mid-depth of water column. The dominance index was high at the AVI (0.778) and NVA (0.868), whereas the diversity index and evenness index were high at the VFA. Fish distribution at AVI was similar to that of the NVA in numbers of species, indicating that the AVI could playa role as spawning and inhabitation zone to a variety of fishes. We believe that AVI may be used for a restoration of the damaged and disturbed littoral ecosystem.

• Journal of Korea Water Resources Association
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• v.39 no.3 s.164
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• pp.227-240
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• 2006

In the several decades, various storage facilities have been developed and operated to supply water resource, flood control or environmental preservation etc. Then, how those man-maid storage facilities affect on the downstream water and environment and how the hydrologists can evaluate those features for water resources problem-solving are high-concentrated problems in this field. Most large watersheds in Korea contain various types of artificial facilities such dams, reservoirs, in-land ponds, wetlands etc. But the study to develop the technology for achieving the effect of the variances and properties of the long term streamflow caused by the artificial storage facilities have been on the simple watershed models and experimental modeling in the real fields. In this paper, we introduce the procedure and methods to consider the above problems based on continuous and semi-distributed featured SWAT model. At the first, we describe the elements and mechanisms of storage facilities in SWAT model to see how we can apply that in proper and appropriate manner for real field problems. Then, we applied the process to a sample watershed, Taewha River basin which covers the most of Ulsan region. Specially, we concentrate on our effort to the effect of upper reservoirs on down stream long term flows based on various scenario basis. The result was described and analysed in spacial and temporal variations on that basin using the precise manner.

• Journal of Ecology and Environment
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• v.38 no.3
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• pp.375-381
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• 2015

We investigated the influence of summer rainfall on Pectinatella magnifica colonies in lotic ecosystems. Of the examined substrate materials, branches and aquatic macrophytes supported more colonies of P. magnifica than that by stones or artificial materials. The influence of rainfall on P. magnifica colonies differed in accordance with the type of substrate material at each study site. In the Geum River, little difference was noted in the number of P. magnifica colonies on branches before ($mean{\pm}SE$, $24{\pm}7.3$ individuals) and after rainfall ($20{\pm}8.4$ ind.); other substrate types supported fewer colonies of P. magnifica after rainfall. In contrast, in the Miryang River, rainfall had minimal effect on the number of P. magnifica colonies supported by macrophytes ($13{\pm}3.8$ and $12{\pm}4.3$ ind., respectively). Artificial material was more abundant in the Banbyeon Stream where it was able to support more colonies of P. magnifica. We found that the structure of different substrates sustains P. magnifica following rainfall. In the Miryang River, free-floating and submerged plants with a relatively heterogeneous substrate surface were the dominant macrophytes, whereas in the Geum River, simple macrophytes (i.e., emergent plants) were dominant. Therefore, we conclude that the substrate type on which P. magnifica grows plays an important role in resisting physical disturbances such as rainfall.

• Journal of the Korean Society of Combustion
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• v.21 no.1
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• pp.38-45
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• 2016

Flame characteristics and NO emission behavior in $CH_4$/air-air premixed counterflow flames with applying FIR and FGR with $CO_2$ and $H_2O$ were investigated numerically by varying the ratios of FIR and FGR as well as global strain rate. Chemical effects of added $CO_2$ and $H_2O$ via FIR and FGR were analyzed through comparing flame characteristics and NO behaviors from real species($CO_2$ and $H_2O$) with those from their artificial species($XCO_2$ and $XH_2O$) which have the same thermochemical, radiative, and transport properties to those for the real species. The results showed that flame temperature and NO emission with FIR varied much more sensitively than that with FGR. Those varied little irrespective of adding $CO_2$, $H_2O$, and their artificial species to the fuel stream via FIR. However, Those were varied complicatedly by chemical effects of added $CO_2$ and $H_2O$ via FGR. Detailed analyses for them were made and discussed.

• Journal of Ecology and Environment
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• v.43 no.4
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• pp.461-468
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• 2019

Background: This study aimed to identify NO₃^--N sources using the stable isotope δ¹⁵N in Chydorus sphaericus (OF Müller), to investigate hydrological characteristics and nutrient states in artificial wetlands near the Nakdong River. Chydorus sphaericus is dominant in wetlands where aquatic plants are abundant, occurring in high density, and is sensitive to wetland water pollution, making it suitable for identification of NO₃^--N sources. Results: NO₃^--N sources for each wetland were strongly dependent on hydrological characteristics. Wetlands with sewage or rainfall/groundwater as their main sources had high levels of NO₃^--N, whereas wetlands with surface water as their main input had comparatively lower levels. Since wetlands with sewage and rainfall/groundwater as their main water sources were mostly detention ponds, their inputs from tributaries or the main river stream were limited and nutrients such as NO₃^--N easily become concentrated. Changes in NO₃^--N levels at each wetland were closely associated with δ¹⁵N of C. sphaericus. Interestingly, regression analysis also showed positive correlation between δ¹⁵N of C. sphaericus and NO₃^--N level. Conclusions: We conclude that the nitrate stable isotope (δ¹⁵N) of C. sphaericus can be used to elucidate the hydrological characteristics of riverine wetlands. This information is important for maintenance and conservation of artificial wetlands at the Nakdong River.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.35-35
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• 2019

본 연구에서는 분포형 수문 모형 Drying Stream Assessment Tool and Water Flow Tracking (DrySAT-WTF)을 활용해 우리나라의 1976년부터 2015년까지의 유출량을 산정하고, 이를 다층퍼셉트론(Multi Layer Perceptron) 인경신경망 모형(Artificial Neural Network Model)에 적용해 미래 유출을 예측하였다. DrySAT-WFT은 전국 표준 유역을 대상으로 하천 건천화 원인 추적 및 평가를 위해 개발된 모형으로 유출모의를 위한 기상자료 외에 건천화 영향 요소를 고려하기 위한 산림 높이, 도로망, 지하수 이용량, 토지이용, 토심 변화에 대한 DB를 적용 가능한 것이 특징이다. DrySAT-WFT를 위한 기상자료로 모의 기간에 대한 일별 강우량, 상대습도, 평균풍속, 평균 및 최고, 최저 기온, 일조시간을 구축하였으며, 연대별 건천화 영향 요소 DB를 구축하여 적용하였다. 전국 다목적 댐 보 12지점의 유량을 활용해 모형의 보정(2005-2010) 및 검증(2011-2015)을 실시한 결과, 평균 결정계수(Coefficient of determination, $R^2$)는 0.76, 모형효율성계수(Nash-Sutcliffe efficiency, NSE)는 0.62, 평균제곱근오차(average root mean square error, RMSE)는 3.09로 신뢰성 있는 유출 모의 결과를 나타내었다. 미래 유출량 예측을 위한 MLP-ANN은 1976년부터 2015년까지의 유출 모의 결과를 Training Set으로 훈련하여 $R^2$가 0.5 이상이 되어 신뢰성을 확보하였고, 2016년부터 2018년까지의 기간을 1개월 단위로 실제 유출량과 예측 유출량을 비교하며 적용성을 검증 및 향상시켰다.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.6
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• pp.1-12
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• 2022

Estuary reservoirs were artificial reservoir with seawalls built at the exit points of rivers. Although many water resources can be saved, it is difficult to manage due to the large influx of pollutants. To manage this, it is necessary to analyze watersheds and reservoirs through accurate modeling. Therefore, in this study, we linked the Hydrological Simulation Program-FORTRAN (HSPF), Environmental Fluid Dynamics Code (EFDC), and Water quality Analysis Simulation Program (WASP) models to simulate the hydrology and water quality of the watershed and the water level and quality of estuary lakes. As a result of applying the linked model in stream, R² 0.7 or more was satisfied for the watershed runoff except for one point. In addition, the water quality satisfies all within 15% of PBIAS. In reservoir, R² 0.72 was satisfied for water level and the water quality was within 15% of T-N and T-P. Through the modeling system, We applied upstream pollutant management scenarios to analyze changes in water quality in estuary reservoirs. Three pollution source management were applied as scenarios, the improvement of effluent water quality from the sewage treatment plant and the livestock waste treatment plant was effective in improving the quality of the reservoir water, while the artificial wetland had little effect. Water quality improvement was confirmed as a measure against upstream pollutants, but it was insufficient to achieve agricultural water quality, so additional reservoir management is required.

• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.338-347
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• 2008

Grazing rate (GR) and feces production (FP) of freshwater snail Cipangopaludina chinensis malleata on two hibernal diatom communities were examined in a laboratory. Snail with the similar size (4.2$\sim$5.8 cm) were collected from the Gunsan and Okgu district (Jeonbuk), transferred to the artificial management system in laboratory, and starved for 3 day before the experiment. The feeding experiments were conducted at various conditions such as passage of time (0, 1, 4 and 7 hr), snail density (0.0, 0.5, 1.0, 2.0 and 4.0 ind. $L^{-1}$) and kinds of prey (cold lake and stream water). One prey used in this study is the water of Lake Ilgam, the other is that of Han river. Lake Ilgam water was dominated by Synedra ulna (69.1%) and Scenedesmus sp. (6.6%), while Han river was by Asterionella formosa (69.4%) and Diatoma vulgare (27.7%). With the increment of snail density and time, the Chl-a concentration of two experimental waters were clearly decreased. Chl-a of Han river rapidly was decreased after 1 hour of snail treatment, while that of Ilgam lake was decreased after 4 hour. On the passage of time, a highest GR (1.94 L $g^{-1}\;h^{-1}$) showed at 1 hr, and then, decreased gradually to 0.04 L $g^{-1}\;h^{-1}$ by 7 hr. The highest FP (0.11 mg $L^{-1}$) showed at 7 hr. These results indicate that native snail Cipangopaludina chinensis malleata may be applied as a potential bio-filter to control diatom blooms in the cold lake and stream.