• Proceedings of the Korea Water Resources Association Conference
• /
• 2010.05a
• /
• pp.1500-1504
• /
• 2010

본 연구에서는 EFDC(Environmental Fluid Dynamics Code) 모형을 이용하여 이원 담수화호의 염분분포를 모의하였다. SMS(Surface Water Modeling System) 모형을 이용하여 담수호에 대한 격자망을 구성하였다. 격자체계는 직교좌표계를 사용하였으며, 전체 2,620개의 유효계산격자를 구성하여 모형에 적용하였다. 수위 및 유량에 대한 경계조건은 기상자료와 배수갑문 운용자료를 통해 구축하였으며, 초기조건은 수위 실측자료를 이용하였다. 담수호의 염분모의를 위한 모형의 경계 조건은 호내에 위치한 5개소의 실측자료를 이용하였으며, 유역에서의 유입수염분농도는 0.2 ppt, 방조제 외측으로부터의 유입수 염분농도는 해수조건(30 ppt)을 적용하였다. 염분분포 모의를 위해 2006년부터 2008년까지 3년동안의 염분농도 실측자료를 이용하여 보정과 검정을 실시한 결과, 대상 지역에 대해 EFDC 모형의 적용성이 있는 것으로 나타났다.

• Proceedings of the Korean Aquaculture Society Conference
• /
• 2003.10a
• /
• pp.102-102
• /
• 2003

황복(Takifugus obscurus)은 주로 황해에 분포하며 봄철에 서해안으로 흐르는 금강, 한강 및 임진강으로 소상하여 강의 중상류에서 산란하는 소하성어류이다. 특히 황복은 바다와 하천을 오고 가는 관계로 해수뿐만 아니라 민물에서도 양식이 가능한 어종으로 다른 소하성어류와 마찬가지로 염분변화에 따른 삼투조절능력이 매우 우수할 것으로 생각된다. 본 연구는 황복이 급격히 염분을 달리하였을 때 나타나는 생리적 반응을 산소소비량과 암모니아 질소배설량의 변화로 염분변화에 따른 생리적 적응력을 살펴보고자 하였다. 본 연구에 사용한 황복은 전장 10cm(체중 15~25g) 전후의 치어로서 염분 32, 22, 12, 및 2 ppt로 조절되어 있는 FRP수조(500 L)에서 2개월간 사육 후, 각기 염분을 달리한(32, 22, 12, 2 ppt) 호흡측정 장치에 황복을 수용하여 산소소비량과 암모니아 질소배설량을 측정하였다. 한편, 사육 시스템내에서의 산소소비와 암모니아 질소의 배설경향을 보기 위하여 염분 16ppt에서 산소소비량과 암모니아 질소배설량을 25시간 관찰하였다. 산소소비 경향은 대체로 염분이 낮을수록 높은 산소소비 경향을 보였는데, 실험염분 32ppt에서는 2~32ppt 사육군 모두 다른 실험염분(22, 12, 2 ppt) 사육군보다 안정되고 낮은 산소소비량을 나타내었다. 그리고 실험염분 22, 12 및 2 ppt에서는 각기 실험염분과 동일한 염분 사육군에서 가장 높은 산소소비량을 나타낸 반면 32 ppt 사육군은 모든 실험염분에서 가장 낮은 산소소비량을 나타내었다. 암모니아 질소의 배설경향은 실험염분 2 ppt를 제외하고는 2 ppt 사육군에서 가장 높은 질소 배설율을 보였으나, 실험염분 2 ppt에서는 오히려 현저히 낮은 암모니아 질소 배설율을 나타내었다. 저 염분(2, 12 ppt)에서 사육한 황복은 22 및 32 ppt에서 사육된 황복에 비해 저염분에 노출될 경우 삼투조절을 위해 암모니아 배설에 상당한 차이를 보였다. 사육 시스템내에서 조사된 산소소비와 암모니아 질소 배설경향은 섭이와 관련하여 일간리듬을 보였는데, 산소소비는 섭이 3시간 후에 최고를 보였으며 암모니아 질소 배설은 섭이 4시간 후에 각각 최고를 나타내었다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.90-90
• /
• 2019

본 연구에서는 SWASH(Simulating WAves till SHore) 모형의 염분분포 해석의 정확성을 평가하기 위해 Goswami et al.(2007)의 모형실험을 재현하였다. SWASH모형은 Delft 대학에서 개발된 비정수압수치모형으로 연직방향으로 층(layer)을 나누어 자유수면변위를 정확하게 예측하고 표준 ${\kappa}-{\varepsilon}$ 난류모델을 이용해 염분, 온도 및 침전물 등의 난류확산을 계산한다. 우선 Goswami et al.(2007)의 모형실험 중 정상상태의 모형실험을 이용해 층수에 따른 수치모형의 정확도를 평가하였다. SWASH 모형의 층수를 늘리며 수치모의를 수행한 결과, 층수가 늘어날수록 종, 횡 방향의 염분농도 분포가 정확하게 나타나는 것을 확인하였다. 추가로 SWASH 수치모형을 이용해 염수침투 및 후퇴 상태의 모형실험도 수치모의하였다. 염수의 공급에 따라 시간에 따른 염분농도 분포가 변화하는 것을 확인하였다. 또한 연직방향의 층수가 많은 경우 모형실험의 결과와 비교적 잘 일치하는 것을 확인할 수 있다. 따라서 연직방향의 층수를 늘려감에 따라 수심방향으로 더 정밀한 염분분포 해석이 가능하다는 것을 알 수 있다. 그러나 연직방향으로 많은 층을 나눈 경우 계산시간이 증가하기 때문에 수심이 작거나 연직방향의 염분농도 분포가 중요하지 않은 경우라면 적절한 층수(5~10 layer)를 고려해 수치모의를 수행하는 것이 시간과 비용측면에서 더욱 경제적이라고 할 수 있다.

• Journal of Korea Water Resources Association
• /
• v.53 no.7
• /
• pp.481-491
• /
• 2020

The development of agricultural land at Saemangeum has required a significant increase in agricultural water use. It has been well acknowledged that salinity plays a critical role in the farming system. Therefore, a systematic study in salinity is necessary to better manage agricultural water. This study aims to develop a stochastic salinity simulation model that simultaneously simulates salinities obtained from different layers. More specifically, this study proposed a two-stage Autoregressive Exgeneous (ARX) model within a hierarchical Bayesian modeling framework. We derived posterior distributions of model parameters and further used them to obtain the predictive posterior distribution for salinities at three different layers. Here, the BIC values are used and compared to determine the optimal model from a set of candidate models. A detailed discussion of the model is provided.

• The Korean Journal of Malacology
• /
• v.30 no.4
• /
• pp.363-370
• /
• 2014

We investigated the survival rate by water temperature and salinity, physiological rhythm and morphological change of live abalone to get to know optimum water temperature and salinity suitable for long-distance transportation of live abalone. At $8^{\circ}C$ and above, 96-100% of survival rate was shown at all experiment groups. At $6^{\circ}C$, 66% of abalones survived in normal seawater but they showed 0% of survival rate at $30{\pm}0.5psu$ and $26{\pm}0.5psu$ of salinity at the same water temperature. There was no significant difference of oxygen consumption rate for a week between the seawater and $30{\pm}0.5psu$. Also, a positive correlation was shown between salinity and water temperature and the oxygen consumption rate was slightly higher at $30{\pm}0.5psu$ than seawater. Thinned epithelial layers and expansion of lymph sinus were observed less than $30{\pm}0.5psu$ or below $6^{\circ}C$ of temperature. This result shows that the optimum level of water temperature and salinity is considered to be $6-8^{\circ}C$ and more than $30{\pm}0.5psu$ respectively.

• Journal of Aquaculture
• /
• v.13 no.4
• /
• pp.317-323
• /
• 2000

Experimental cohorts of Mugil cephalus were divided into 5 groups : seawater~normal feed (SWN), acclimation to freshwater~normal feed (GFWN), acclimation to freshwater~salt feed (Gf\iVS), freshwater. normal feed (FWN) and freshwater-salt feed (f\iVS). Growth was faster in the SWN, Gf\iVS, and GFWN groups than in the f\iVS and FWN groups. Condition factor did not differ among the groups. Survival (92 %) of the juveniles was the highest in the Gf\iVS group; however, the others showed no significant difference. Moisture of FWN group was significantly higher than that of SWN group (P < 0.05). Potassium concentration was significantly higher in the SWN group than that of others (P < 0.05). It was highest (30 mmolfl) among the cohort of SWN.

• Proceedings of KOSOMES biannual meeting
• /
• 2003.11a
• /
• pp.181-185
• /
• 2003

the effect if atmosphere is more important in the West sea of Korea than in other seas because of shallow water and heat storage if the water. The serial oceanographic observation data and coastal station data from NFRID, and the atmosphere data from KMA were used in order to find out the relationship between them The highest water temperature, salinity and weather factor were recorded in Aug, and the lowest of them in Feb. As the water deepens, the maximum time leg in water temperature and the minimum time leg in salinity. Water temperature have the maximum in Oct, the minimum in Apr at 75m of the 311-07 station with 100m depth water temperature (WT)-air temperature, WT-precipitation (Preci.) and salinity (Sal)-wind speed (WS) were in direct proportion, but WT-WS, Sal-AT and Sal-Preci in inverse proportion Water temperature and salinity I-ave time leg at the same depth the maximum had more the delay of $2\~4$ months at a depth if 20 meters than at the surface in all stations except for salinity at 307-05.

• Journal of Soil and Groundwater Environment
• /
• v.14 no.6
• /
• pp.1-18
• /
• 2009

A series of three-dimensional numerical simulations using a generalized multidimensional hydrodynamic dispersion numerical model is performed to simulate effectively and to evaluate quantitatively impacts of urbanization on density-dependent groundwater flow and salt transport in a coastal aquifer system, Suyeong-Gu, Busan, Korea. A series of steady-state numerical simulations of groundwater flow and salt transport before urbanization with material properties of geologic formations, which are established by numerical modeling calibrations considering all the urbanization factors, is performed first without considering all the urbanization factors. A series of transient-state numerical simulations of groundwater flow and salt transport after urbanization is then performed considering the urbanization factors individually and all together. Finally, the results of both numerical simulations are compared with each other and analyzed. The results of the numerical simulations show that density-dependent groundwater flow, salt transport, and seawater intrusion in the coastal aquifer system are intensively and extensively impacted by the urbanization factors. Especially, these urbanization factors result in the changes of the total groundwater volume and salt mass in the coastal aquifer system. However, such impacts of each urbanization factor are not spatially uniform but locally different.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.4
• /
• pp.692-697
• /
• 2016

This study examined the effects of salinity and medium used on the induction of sexual reproduction for the mass production of the resting eggs in the marine rotifer Brachionus rotundiformis for 9 days. After exposure to various salinities, the mixis rate in all treatments began to increase on the third day and decreased after the 4th or 5th day. The resting eggs appeared on the 4th day at 10‰, 15‰, 20‰, 25‰. In particular, the fertilization rates with 33.3% and 31.3% at 20‰ and 25‰ on day 6 were higher than those of the others, respectively. Mean mixis rate for 9 day at 0‰ and 20‰ were the highest with 25.3% and 20.2%, respectively, and the fertilization rate (14.0%) at 25‰ was the highest. In the medium experiment used, the mixis rate in all treatments were similar to the results of the salinity experiment. The resting eggs were only found at 0% and 25% of the used medium treatments. While there were no significant differences in the mean fertilization rate of all treatments, the mean mixis rate (22.3%) in the 25% treatment was higher than that of the control (0% treatment). As a result, salt stress was more effective than using the used medium to induce sexual reproduction in B. rotundiformis. The optimal salinity was considered to be 20-25‰, which caused a high mixis and fertilization rate in the rotifer. These results provide basic data for the mass production of rotifer resting eggs.

• Journal of Korea Water Resources Association
• /
• v.47 no.3
• /
• pp.297-306
• /
• 2014

In this study, EFDC (Environmental Fluid Dynamics Code) model was used to simulate the salinity distribution for sea water inflow and rainfall runoff. The flowrate was given to the boundary conditions, which can be calculated by areal-specific flowrate method from the measured flowrate of the representative outfall. The boundary condition of the water elevation can be obtained from the hourly tidal elevation. The flowrate from the outfall can be calculated using the condition of the 245 mm raifall. The simulation results showed that at Sites 1~2 and the Mangsan island (Site 4) the salinity becomes 0 ppt after the rainfall. However, the salinity is 30 ppt when there is no rainfall. Time series of the salinity changes were compared with the measured data from January 1 to December 31, 2010 at the four sites (Site 2~5) of Yongwon channel. Lower salinities are shown at the inner sites of Yongwon channel (Site 1~4) and the sites of Songjeong river (Site 7~8). The intensive investigation near the Mangsan island showed that the changes of salinity were 21.9~28.8 ppt after the rainfall of 17 mm and those of the salinity were 2.33~8.05 ppt after the cumulative rainfall of 160.5 mm. This means that the sea water circulation is blocked in Yongwon channel, and the salinity becomes lower rapidly after the heavy rain.