• Geotechnical Engineering
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• v.13 no.2
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• pp.17-28
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• 1997

In this study sodium chloride solution is employed for chemicals, and several cylindrical triaxial tests are performed on the sand-bentonite mixtures saturated with sodium chloride solution. Deformation(elastic modulus, E) and strength(cohesion, c', and angle of friction, f') parameters are obtained from the triaxial tests as functions of confining pressure and sodium chloride solution concentrations. The results here indicate an increase in the value of effective cohesion with increase in the concentration of NaCl solution, which can be explained by using the Gouy-Chapman model. The value of the effective angle of shearing resistance does not show significant change with the increase in concentration of NaCl solution. The Young's modulus also increases with the increase in concentration of NaCl solution.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.295-296
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• 2001

우리나라의 해수어류 양식생산량은 사육환경, 사육관리조건 및 적조, 냉수대, 저염 분수의 양식장내 유입 등 자연재해에 의해 생산량 변동이 심하여 어가의 불안정한 요인으로 작용하고 있다. 집약적 어류양식에서 발생하는 부적당한 환경, 영양 및 인위적 스트레스는 어류의 최적 성장을 저해하며, 양식생산의 계획화에 지장을 초래한다. 환경요인중 수온, 염분 및 수질의 급변은 양식어류에 상당한 스트레스 요인으로 작용하는데, 이중 염분변화는 어류의 체내 삼투압 변화를 유도하고, 이때 어류는 체내 항상성을 유지하기 위하여 삼투압 조절을 한다. (중략)

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.4
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• pp.371-376
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• 1993

This experiment was conducted to elucidate the salt tolerance mechanism of crop plants. Plants used in this experiment were rye, barley, Italian ryegrass. Seeds were treated at saline condition and the saline conditions were controlled by NaCl. The results were summerized as follows. In rye, germination ratio and speed were above 90% and 80% at NaCl concentrations below 0.5% but germination ratio was seriously decreased at NaCl concentration above 0.6%. In barley germination ratio was not less than 80% at NaCl concentration below 0.8%. In italian rye grass germination ratio was decreased gradually by increasing NaCl concentration but germination speed was seriously decreased at NaCl concentration above 0.6% as not more than 7.5%. Water absorption rate was low in barley than rye and it was decreased by increasing NaCl concentration and duration of absorption. In barley, carbohydrate content was decreased slightly in response to increased NaCl concentration and content of reducing sugar was independent of NaCl concentration. In rye, reducing sugar content was increased until 0.3% of NaCl and increased seriously after 20 hours. $\beta-Amylase activity was high at control and 0.6% lot of NaCl, but it was not general tendency.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1895-1899
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• 2006

Seawater intrusion phenomenons of coastal area happen by natural or artificial factor. For example, density difference of seawater and fresh water, surface of the water change by tidal current, pumping, aggregate picking from mouth of a river, large scale reclamation in water area business etc. This research analyzed effect that groundwater TDS changed by pumping.As a result, it was expose that TDS density increases by sudden inflow of seawater when do pumping up more than $200m^3/day$. Finally, We are expected to prevent calamity by seawater intrusion in coastal area through this study and propose optimum pumping amount to use groundwater safety.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.81-81
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• 2015

전 지구적 기후변화는 대기-해양의 물리 특성을 변화시켜, 연안 및 하구의 수온상승과 염도 변화의 주요 원인이 되며, 생태 환경 및 다양한 경제 사회 문제를 야기 시킬 수 있다. 이러한 변화를 예측하고 영향을 최소화 하기위해서는 연안의 물리 특성을 세밀하고 정확하게 예측해야 한다. 그러나, 기후변화의 영향을 고려한 대기-해양 전 지구모델의 기후변화 시나리오는 우리나라와 같이 작고 복잡한 연안 지형을 가진 지역의 미래 환경 변화 예측에 적합하지 않다. 본 연구에서는 저해상도 정규격자 모형인 RIAMOM(RIAM Ocean Model)의 결과를 이용하여 비정규격자 모형인 FVCOM(Finite Volume Coastal Ocean Model)으로 울산만의 미래 물리 특성 변화를 상세 예측하였다. 기후변화로 인한 대기-해양의 물리 특성 변화를 고려하여 한국 주변해 및 연안을 대상으로 모의한 RIAMOM의 결과를, 본 연구의 대상 지역인 울산만 FVCOM 모델 경계에 초기 값과 시계열 자료로 사용하였다. FVCOM 모의 결과를 RIAMOM 자료와 비교 했을 때, 초기 표층 염분과 수온이 각각 0.4%, 2%의 오차를 보였다. 조위는 개방경계에서 01~0.4% 정도의 오차가 나타나, 다운스케일링(downscaling) 기법을 통한 수치 모의 결과가 초기 수온과 염분 및 조위 특성을 잘 재현하는 것으로 나타났다. 2001년(현 상태), 2050년(미래), 해수면 상승의 영향을 고려한 2050년에 대하여 모의 한 결과. 정규격자 모형인 RIAMOM에서 나타나지 않았던 기후변화로 인한 표층 염분과 수온의 상세한 변화가 울산만의 태화강 하구에서 나타났고, 염수쐐기의 길이 또한 상류쪽으로 증가하는 결과를 나타내었다. 다운스케일링을 통한 대상 지역의 상세 모델을 통해 기존의 예측 모델에서도출할 수 없던 결과를 나타낸 바, 향후 연구를 통해 지역의 장기 상세 환경 변화 예측에 활용할 수 있을 것으로 예상한다.

• Journal of Korea Water Resources Association
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• v.44 no.1
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• pp.23-30
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• 2011

Any significant inflow of fresh water due to flood or snow melting can rapidly reduce salinity at the bay. In such a case, the habitat environment in the sea near river mouth can be partly destroyed. Therefore, research to understand the salinity distribution quantitatively at the bay for the utilization of natural environment and for the inhabitant conservation must be very important. In this study, the investigation on the relationship between satellite image and turbidity is carried out first, and then the salinity distribution at the bay using the relationship between turbidity and salinity is derived. The main results are as follows. First the reappearance ability of RGB bands respectively of the satellite image is investigated, and then it was confirmed that the combination of band2 and band3 expressed best the movement characteristics of turbid water at the bay is chopped up into 4 small areas. Second the turbidity of river mouth is estimated using the travel time from the upward monitoring station to the river mouth. Finally the satellite image is converted into the salinity distribution by the correlation of salinity and turbidity. It is confirmed that the salinity distributions obtained from above three investigation methods are quite reasonable and clear.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.632-640
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• 2017

In order to understand the seasonal and geographical characteristics of environmental factors and distribution of Escherichia coli by salinity gradient due to precipitation, we investigated abiotic and biotic factors during four seasons from February 2013 to November 2015. The study area was divided into three different zones based on salinity gradient and geo-oceanographic characteristics. During the study period, water temperature, salinity, Chlorophyll a, and secchi-depth varied in the range of $8.5-26.1^{\circ}C$, 13.5-34.4 psu, $0.4-74.0{\mu}g\;L^{-1}$, and 0.5-10.0 m, respectively. Salinity was low at Zone I, which was influenced by water flux from Tae-hwa River, especially in 2014. Salinity was gradually increased (one-way ANOVA; p < 0.05) toward Zone III located offshore of the bay. The highest colony form of E. coli was detected at Zone I. E. coli maintained a relatively low level at Zone III during all seasons. E. coli was correlated with transparency (r = -0.36; p < 0.05) and salinity (r = -0.53; p < 0.01), implying that those parameters might play important roles in the proliferation of E. coli. These results indicated that E. coli were strongly affected by frequent rain (< 50 mm) around inner stations in Ulsan Bay of Korea.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.866-873
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• 2022

Growth rate and production of the paralytic shellfish poisoning toxin (PST) of a toxic dinoflagellate Alexandrium pacificum (LIMS-PS-2611) isolated from the southern sea of Korea, were examined under various temperatures and salinity conditions. The maximum growth rate (0.28 day^-1) was observed under 25℃ and 30 psu. Optimal growth (≥ 70% of maximum growth rate) was obtained between 20~25℃ and 25~35 psu. Among the PSTs of A. pacificum, the principal toxins were C1+2 and GTX5 in N-sulfocarbamoyl toxin group, and minor components were characterized as neoSTXs in the carbamate toxin group. Maximum toxin content was observed under 20℃ and 30 psu, and the toxin content increased with the increase of salinity. Low toxin contents were measured under the temperature and salinity conditions of the maximum growth rate. Therefore, the PSP of bivalve, which occurs at a temperature range of 20-25℃ in June, might have been derived from A. pacificum.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2007.05a
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• pp.292-293
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• 2007

한국 남해안에서 2005년 10월부터 2006년 8월까지 격월별로 관측된 CTD 자료 및 분석된 영양염 자료를 가지고 격월별 해황 및 영양염의 분포를 살펴 보았다. 겨울철에는 표층과 저층간의 수직 혼합으로 일정한 수괴 분포 및 수온과 염분에 대해서 일정한 영양염 분포를 나타내었다. 그리고 연안역과 외양역 사이에 수온 전선이 뚜렷하였다. 그러나 여름철에는 양자강 저염수의 유입으로 T-S상에서 수형의 분포 범위가 넓었으며, 또한 수온과 염분에 대한 영양염의 분포도 일정하지 않았다. 그리고 여름철에는 저염수 유입에 의해서 수온 전선보다는 염분 전선이 뚜렷하였다. 봄과 가을에는 계절적 천이기로 수온과 염분의 분포에서 뚜렷한 pattern을 보이지 않았다.

• Smart Media Journal
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• v.11 no.2
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• pp.31-38
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• 2022

Promptly predicting changes in the salinity in rivers is an important task to predict the damage to agriculture and ecosystems caused by salinity infiltration and to establish disaster prevention measures. Because machine learning(ML) methods show much less computation cost than physics-based hydraulic models, they can predict the river salinity in a relatively short time. Due to shorter training time, ML methods have been studied as a complementary technique to physics-based hydraulic model. Many studies on salinity prediction based on machine learning have been studied actively around the world, but there are few studies in South Korea. With a massive number of datasets available publicly, we evaluated the performance of various kinds of machine learning techniques that predict the salinity of the Nakdong River Estuary Basin. As a result, LightGBM algorithm shows average 0.37 in RMSE as prediction performance and 2-20 times faster learning speed than other algorithms. This indicates that machine learning techniques can be applied to predict the salinity of rivers in Korea.