• Korean Journal of Environmental Agriculture
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• v.1 no.1
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• pp.31-38
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• 1982

The water quality at the Nakdong River stream was surveyed for 3 years from 1978 to 1980 at quarterly intervals of January, April, June and October at 12 sites along the main stream from Sangju to Imhaejin and at 2 sites of Geumho and Nam River tributaries. The overall results are summarized as follows: 1) The levels of dissolved oxygen in the Geumho River tributary on the basis of three-year average were 0.7 ppm in January, 1.3 ppm in April, 4.0 ppm in July and 0.8 ppm in October. BOD concentrations in the same period were 91 ppm in January, 37 ppm in April, 6 ppm in July and 24 ppm in October. The water of Geumho River was so highly contaminated that the water seems to be unsuitable for any type of water use. 2) The relatively clean water in the upstream of the main Nakdong River was rapidly polluted by the highly contaminated water of Geumho tributary. That is, dissolved oxygen and BOD at Hwawon site right after junction of the tributary were 10.4, 8.8 ppm in January, 5.8, 6.5 ppm in April, 6.3, 3.2 ppm in July and 7.0, 5.3 ppm in October, respectively. The values of turbidity, ammoniacal nitrogen and electrical conductivity were also observed to be quite high.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.2
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• pp.17-26
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• 2015

River corridors facilitate dispersal and movement and prevent local extinction of species. As a result of stream restoration projects, which include installation of waterfront and flood control structures, the number of animals, which rely on river corridor, is decreasing. For the study, factors affecting fish assembly were extracted by a species distribution model with the fish data collected from the Seom River in Hoengseong County and City of Wonju, Ganwon Province, Korea between March to October 2013. The riparian connectivity was assessed using species richness and rarity. According to result of the field survey, there were 38 species and 7,061 individuals for fish. The analysis suggests the following. Firstly, factors affecting fish richness in species distribution model results are shown to be velocity, riffle, riparian width, and water width. The accuracy of the model proves to be suitable with the correlation coefficient of 0.83 and MAPE of 19.2%. Secondly, the low rarity area is shown to be straight streams in Jeon river near to Hongseong County and the high rarity area to be streams with large width, existing alluvial area at channel junction between Jeon river and Seom river. Thirdly, according to connectivity results, areas where weirs are installed or riparian buffer area is removed showed low connectivity. The areas where farmland near riparian and forest areas showed high connectivity. The results of this study can be utilized to improve current facilities and enhance connectivity as a restoration guide.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.249-249
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• 2017

본 연구에서는 낙동강 본류의 진동과 적포교, 남강의 거룡강, 대산, 정암 수위표의 관측된 2015년부터 2016년 2년간 수위자료를 이용하여, Self-Organizing Maps(SOM)과 LOcally WEighted Scatter plot Smoother(Lowess) 기법으로 패턴과 추세를 분석하였다. SOM 분석 결과, 낙동강 본 류의 진동과 적포교, 남강의 거룡강, 대산은 동일한 패턴과 추세를 나타냈다. 수위의 범위도, SOM 분석에서 진동 최소 EL. 4.41m, 최대 EL. 5.01m 범위, 적포교 최소 EL. 4.56m, 최대 EL. 5.38m 범위, 거룡강 최소 EL. 4.53m, 최대 EL. 5.18m 범위, 대산 최소 EL. 4.57m, 최대 EL. 5.35m 범위로 큰 차이가 발생하지 않았다. 거룡강과 대산 수위 관측지점은 낙동강 본류의 배수위 영향을 받는 것을 알 수 있었으며, 두 지점의 수위 관측 목적에 따라 상류로 지점 변경이 필요 할 수도 있을 것으로 판단된다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.6
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• pp.308-320
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• 2021

An integrated sediment management approach that includes the recovery of the amount of declined sediment supply is effective as a fundamental solution to coastal erosion. During planning, it is essential to analyze the transfer mechanism of the sediments generated from estuaries (the junction between a river and sea) to assess the amount and rate of sediment discharge (from the river to sea) supplied back to the coast. Although numerical models that interpret the tidal sand bar flushing process during flooding have been studied, thus far, there has been no study focusing on the formation and development processes of tidal sand bars. Therefore, this study aims to construct wave deformation, flow regime calculation, and topographic change analysis models to assess the amount of recovered sediment discharge and reproduce the tidal sand bar formation process through numerical analysis for integrated littoral drift management. The tidal sand bar formation process was simulated, and the wave energy and duration of action concepts were implemented to predict the long-term littoral movement. The river flux and wave conditions during winter when tidal sand bars dominantly develop were considered as the external force conditions required for calculation. The initial condition of the topographic data directly after the Maeupcheon tidal sand bar flushing during flooding was set as the initial topography. Consequently, the tidal sand bar formation and development due to nearshore currents dependent on the incident wave direction were reproduced. Approximately 66 h after the initial topography, a sand bar formation was observed at the Maengbang estuary.

• Animal Bioscience
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• v.35 no.11
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• pp.1711-1724
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• 2022

Objective: The present study was to evaluate the effects of different rapeseed meal substitution (RSM) and glutamine (Gln) supplementation on growth performance, intestine morphology, and intestinal mucosa barrier of broilers. Methods: Four hundred and twenty Qiandongnan Xiaoxiang Chicken at 1 day of age with similar weight were chosen and were randomly assigned into 7 groups, consisting of 10 replicates per group and 6 broilers per replicate. Three groups were provided with diets separately containing 0%, 10%, and 20% RSM, and the other four groups were fed with diets separately supplemented with 0.5% and 1% Gln based on the inclusion of 10% and 20% RSM. At 21 and 42 days of age, 10 broilers per group were chosen to collect plasma and intestinal samples for further analysis. Results: The results showed that 10% RSM decreased average daily feed intake (ADFI) and average daily weight gain (ADG) of broilers at 21 days of age (p<0.05). Furthermore, both ADFI and ADG of broilers at 21 and 42 days of age were decreased by 20% RSM, while feed conversion ratio (FCR) was increased (p<0.05). Besides, 10% RSM resulted in lower intestinal villus height and the ratio of villus height to crypt depth, deeper crypt depth (p<0.05), combined with the lower mRNA expressions of occludin, claudin-1, and zonula occludens-1 (ZO-1) in broilers at 21 days of age (p<0.05). Similar results were also observed in broilers at 21 and 42 days of age fed with 20% RSM. However, 1% Gln improved the growth performance of broilers fed with 10% and 20% RSM (p<0.05), ameliorated intestine morphology and elevated mRNA expressions of occludin, claudin-1 and ZO-1 (p<0.05). Conclusion: In conclusion, the increasing inclusion of RSM resulted in more serious effects on broilers, however, 1.0% Gln could reverse the negative effects induced by the inclusion of RSM.

• Korean Journal of Ecology and Environment
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• v.56 no.1
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• pp.1-13
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• 2023

Targeting Microcystin (MC), which is most abundantly detected in the North-Han River water area, we analyzed the relationship between the MC biosynthesis gene (mcyA gene), cyanobacteria cell density, and MC concentration, derived an RNA-MC conversion formula, and derived the cyanobacteria. The concentration of MC present in cells was predicted. In the North-Han River waters, the mcyA gene was found mainly at downstream sites of the North-Han River after Muk-Hyeon Stream junction, and higher copy numbers were found on average than other sites. In the Uiam Lake waters upstream of the North-Han River, the mcyA gene copy number increased at the Kong-Ji Stream point, and after September, the mcyA gene copy number decreased throughout the North-Han River waters. The expression of the mcyA gene was concentrated in the short period of summer due to the spatio-temporal difference between upstream and downstream water bodies. The mcyA gene expression level was not only highly correlated with MC concentration, but also correlated with the cell density of Microcystis aeruginosa and Dolichospermum circinale, which are known to biosynthesize MC. Six conversion formulas derived based on the RNA-MC relationship showed statistical significance (p<0.05) and exhibited high correlation coefficients (r) of 0.9 or higher. The expression level of MC biosynthesis gene present in eRNA determines the synthesis of cyanotoxin substances in water, quickly quantifies gene activity, and can be fully utilized for early warning of MC development.

• Journal of Animal Science and Technology
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• v.53 no.6
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• pp.549-561
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• 2011

Livestock wastewater is being discharged without treatment from Hasen's pig farm cluster in WangGoong (WG) area into the Iksan Stream, eventually flowing into the ManGyung (MG) at the upstream junction. Although it is well known that before discharge, wastewater must satisfy the pig slurry discharge standards; because of ongoing remodeling, proper treatment is not being performed. According to public records, wastewater from the WG pig farm cluster is responsible for 3.6% of MG River pollution and 2.0% of the SaeManGuem (SMG) Reservoir pollution. As a result, upstream water treatment quality has become primary concern for development of the SMG project. All physicochemical constituents and pathogenic microbes, such as chemical oxygen demand ($COD_{Cr}$), biochemical oxygen demand ($BOD_5$), total suspended solids (TSS), total nitrogen (TN), total phosphorous (TP), fecal coliforms, Escherichia coli and Salmonella at the effluent of WG Plant (S-1) exceed the effluent standards. This is mainly due to insufficient wastewater treatment: the WG Plant is under renovation to increase water purification efficiency. By comparing the water quality at the S-7 junction, where the the Iksan Stream (pig farms) and the Wanggoong Stream (no pig farms) merge, it is clear that farming facilities and improper treatment can critically affect surrounding water quality. While it is clear throughout this study that the level of all physicochemical parameters and pathogenic microbes along the Stream decreased due to sedimentation, biodegradation and/or dilution. An alarming problem was discovered: the existence of pathogenic microbe count(E coli, Salmonella) in the lagoon wastewater and the stream water. Not only were high concentrations of these pathogens themselves found, but the potential existence of more serious pathogens could rise to more dangerous conditions.

• Korean Journal of Environmental Agriculture
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• v.21 no.4
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• pp.243-247
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• 2002

Irrigation water quality along Donjin river watershed was monitored to find a possible pollutant, for maintaining water quality to achieve food safety through water quality preservation of river. As a pollution indicators, such as Biological Oxygen Demand(BOD), Chemical Oxygen Demand(COD), Total Nitrogen(T-N), and Total Phosphate(T-P) in Dongjin river were examined from May to November in 2001. The results were as follows : The BOD level of Dongjin river ranged from 2.84 to 6.45 mg/L, which would be in a II$\sim$IV grade of the potable water criteria by Ministry of Environment. Averaged BOD level of downstream DJ6(After Jeongupcheon confluence) was 4.07 mg/L. The average COD level of Dongjin river ranged from 11.20 to 32.96 mg/L. COD level of DJ6 rapidly increased rapidly after the junction of Dongjin river and Jungupcheon because it showed the latter had relatively high pollution level. T-N content were significantly high in all sites of Dongjin river ranged through 4.16 to 5.84 mg/L. T-P examined high concentration than another thing point by 0.19 mg/L after Jeongupcheon confluence as BOD and COD. COD of main stream was expressed high concentration to dry season after rainy season. In case of T-P, pollution degree of dry season before rainy season appeared and examined that quality of water was worsened go by dry season after rainy season. The water quality of Dongjin river was deteriorated with inflow of Jungupcheon polluted by municipal and industrial sites near Jungup city.

• Journal of Korea Water Resources Association
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• v.55 no.4
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• pp.279-289
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• 2022

Since the frequency of heavy rainfall is increasing due to climate change, water levels in the river exceed past historical records. The rating-curve is to convert water level into flow dicscharge from the regression analysis of the water level and corresponding flow discharges. However, the rating-curve involves many uncertainties because of the limited data especially when observed water level exceed past historical water levels. In order to compensate for insufficient data and increase the accuracy of flow discharge data, this study estimates the flow discharge in the river computed mathematically using Monte Carlo simulation based on a 1D hydrodynamic numerical model. Based on the existing rating curve, a random combination of coefficients constituting the rating-curve creates a number of virtual rating curve. From the computed results of the hydrodynamic model, it is possible to estimate flow discharge which reproduces best fit to the observed water level. Based on the statistical evaluation of these samples, a method for mathematically estimating the water level and flow discharge of all cross sections is porposed. The proposed methodology is applied to the junction of Yochoen Stream in the Seomjin River. As a result, it is confirmed that the water level reproducibility was greatly improved. Also, the water level and flow discharge can be calculated mathematically when the proposed method is applied.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.20 no.6
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• pp.107-115
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• 2017

This study illustrated the process of bar structure and vegetation coverage to understand historical changes of riverbed and suppose adaptive management in Tan-chun ecological landscape reserve. The study site that lower reach of the Tan-chun are known as habitats of migratory bird and aquatic species with dynamic riverbed. Aerial photos from 2006 to 2016 and surveyed vegetation data in 2006 and 2016 were used by analysis of landscape changes and comparison of vegetation coverage. Study area is classified into 3 sites (A: straight site, B: meandering site, C: meandering and junction with Yangjae-cheon). The result showed that bar area of A and C sites gradually increased, B site decreased during 10 years. Also, ratio of bar area to vegetation coverage and level of vegetation coverage increased in all sites during 10 years. All sites seem to have experienced the terrestrialization with time. On the other hand, ratio of annual vegetation increased and ratio of perennial vegetation decreased in C site in 2016 compare to 2006. Because area of Japanese Hops (Humulus japonicas) as one type of annual vegetation increased, other vegetation could not grow up by its powerful expandability. It is time to make active adaptive management based on not only continuos monitoring but also revaluation of river conditions in order to enhance habitat quality and quantity in Tan-chun ecological landscape reserve.