• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1571-1580
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• 2008

Subsea tunnels that link land to island and among nations for transportation, efficient development of limited surface and pursuit of economic development should be designed to support pore water pressure on the lining. It is generally constructed in the bed rock of the sea bottom. When the tunnel excavation face meets fractured-zones below sea bottom, collapse may occur due to an increase of pore water pressure and large inflow. Such an example can be found in the Norwegian subsea tunnel experiences in 1980's. In this study hydraulic behavior of tunnel heading is investigated using numerical method based on the collapse of Norwegian subsea tunnel. The effect of pore water pressure and inflow rate were mainly concerned. Horse-shoe shaped model tunnel which has 50 m depth from the sea bottom is considered. To evaluate hydraulic performance, parametric study was carried out for varying relative permeability. It is revealed that pore water pressure has increased with an increase of sea depth. Especially, at the fractured-zone, pore water pressure on the lining has increased significantly. Inflow rate into tunnel has also increased correspondingly with an increase in sea depth. S-shaped characteristic relation between relative permeability and normalized pore water pressure was obtained.

• 한국환경과학회지
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• 제22권8호
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• pp.953-963
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• 2013

Reliable long-term streamflow forecasting is invaluable for water resource planning and management which allocates water supply according to the demand of water users. Forecasting of seasonal inflow to Andong dam is performed and assessed using statistical methods based on hydrometeorological data. Predictors which is used to forecast seasonal inflow to Andong dam are selected from southern oscillation index, sea surface temperature, and 500 hPa geopotential height data in northern hemisphere. Predictors are selected by the following procedure. Primary predictors sets are obtained, and then final predictors are determined from the sets. The primary predictor sets for each season are identified using cross correlation and mutual information. The final predictors are identified using partial cross correlation and partial mutual information. In each season, there are three selected predictors. The values are determined using bootstrapping technique considering a specific significance level for predictor selection. Seasonal inflow forecasting is performed by multiple linear regression analysis using the selected predictors for each season, and the results of forecast using cross validation are assessed. Multiple linear regression analysis is performed using SAS. The results of multiple linear regression analysis are assessed by mean squared error and mean absolute error. And contingency table is established and assessed by Heidke skill score. The assessment reveals that the forecasts by multiple linear regression analysis are better than the reference forecasts.

• 한국수자원학회논문집
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• 제52권7호
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• pp.451-461
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• 2019

장기 기상전망 기반 댐 유입량 전망은 가뭄 대비, 용수 공급 관리 등에 활용성이 높다. 본 연구에서는 국내 7개 다목적댐 유역에 대해 유입량 전망을 수행하고 장기 기상전망 정확도가 댐 유입량 전망 정확도에 미치는 영향을 분석하였다. 강우-유출 모델의 입력자료로 활용된 장기 기상전망 자료는 기상청 GloSea5의 과거재현자료(hindcast) 및 미래전망자료(forecast)를 활용하였다. 강우-유출 모델은 다양한 특성을 가지고 있는 TANK, ABCD, K-DRUM, PRMS를 활용하였다. 댐 유입량 전망 정확도는 과거재현기간(1996~2009)과 미래전망기간(2015~2016)에 대하여 평가하였다. 댐 유입량 전망 평가결과 전망값은 관측값에 비해 과소추정하는 경향을 보였으며, 매개변수 검보정이 적절히 수행된 강우-유출 모델은 댐 유입량 전망 정확도에 미치는 영향이 거의 없는 것으로 나타났다. 반면 장기 기상전망 자료, 특히 강수량은 댐 유입량 전망 정확도에 매우 큰 영향을 미치는 것으로 나타났다. 현업에서 댐 유입량 전망 자료 활용시 과소추정하는 경향을 고려하여 활용할 필요가 있다. 향후 댐 유입량 전망 정확도 개선은 강우-유출 모델 보다 장기 기상전망의 강수량 정확도 향상을 위주로 수행할 필요가 있다.

• 한국패류학회지
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• 제30권3호
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• pp.249-258
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• 2014

Phytoplankton species composition and ecological index (diversity, evenness, richness and dominance) were analysed from April 2013 to March 2014 at 10 stations of cupped oyster, Crassostrea gigas culture area in Iwon coast, Korea. Seasonal and positional variation of phytoplankton standing crops, biomass, dominant species and water quality were distinctively different according to occasionally inflow of Iwon dam reservoired water. The composition of phytoplankton species were Bacillariophyceae 98, Dinophycease 22, Chlorophycease 13, Cyanophyceae 8, Silicofalgellate 4, Euglenophyceae 2, Cryptophyceae 1 species. The most dominant species was Bacillariophyceae as 64.0%. The highest biomass of phytoplankton recorded in September as $40,910{\times}10^3$ cell/L at the station 1, near from inland water inflow area. Ecological indices (diversity, richness, evenness, and dominance index), used for structural change of phytoplankton community and water quality (temperature, dissolved oxygen, salinity) showed difference of spatiotemporal property also.

• 한국해양공학회지
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• 제18권6호
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• pp.22-28
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• 2004

A mathematical model has been developed to evaluate the capability of sea water exchanges under tidal and diffusive environments and has been verified through comparison with numerical experiments. From the mathematical analysis, this study presents the rates of sea water exchanges due to the tidal inflow and diffusion process. The port characteristic length $L_p$ is the most significant evaluation index.

• Journal of the korean society of oceanography
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• 제33권3호
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• pp.41-52
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• 1998

A seasonal circulation pattern in the eastern Yellow Sea (EYS) is suggested from the water mass analysis and geostrophic calculation using the hydrographic data collected by National Fisheries Research and Development Institute during the years of 1970 to 1990. This research focuses on the presence of inflow of warm (and saline) waters into EYS in summer. EYS is divided into two regions in this paper: the west coast of Korea (WCK) and the central Yellow Sea (CYS). In CYS, waters are linked with warm waters near Cheju Island in winter, but with cold waters from the north in summer (in the lower layer). It is not simple to say about WCK because of the influences of freshwater input and tidal mixing. Nevertheless, water mass analysis reveals that along WCK, waters have the major mixing ratios (40-60%) of warm waters in summer, while the dominant mixing ratios (50-90%) of cold waters in winter. Such a seasonal change of water mass distribution can be explained only by seasonal circulation. In winter, warm waters flow northward into CYS and cold waters flow southward along WCK. In summer, warm waters flow northward along WCK and cold waters flow southward into CYS. This circulation pattern is supported by both statistical analysis and dynamic depth topography. Accordingly, Yellow Sea Warm Current may be defined as the inflow of warm waters to CYS in winter and to WCK in summer.

• Ocean and Polar Research
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• 제28권2호
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• pp.153-161
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• 2006

To investigate inflow path of the East Sea Intermediate Water (ESIW) into the Ulleung Basin, hydrographic data surveyed in July 2005 were analyzed. The ESIW was characterized by the Salinity Minimum Layer (SML) within a depth range of 100 to 360 meters. Averaged potential temperature and salinity of the SML were $1.835^{\circ}C$ and 34.049 psu, respectively. Mean potential density $({\sigma}_{\theta})$ of the SML was 27.221 with a standard deviation of 0.0393. On isopycnal surfaces of 27.14 and 27.18 $({\sigma}_{\theta})$ which correspond to upper layers of the ESIW, the coastal low salinity water was separated from the offshore low salinity water by the relatively warm and saline water which might be affected by the Tsushima Warm Current Water. Relatively cold and fresh water, however, intruded into the Ulleung Basin from the region of Korean coast on isopycnal surfaces of 27.22 and 27.26 which was lower layer of the ESIW. The salinity distribution in the isopycnal layer of $27.14{\sim}27.26$ with acceleration potential on 27.22 up surface also showed clearly that the low salinity water flowed from the coastal area and intruded into the Ulleung Basin. This implies that the ESIW flows ken the north to the south along the east coasts of Korea and spreads into the Ulleung Basin in summer.

• 한국환경과학회지
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• 제14권4호
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• pp.397-404
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• 2005

In order to study the temporal variations of nutrients and chlorophyll-a in the Bottol Bada, three field observations were carried out on 20, 23 and 26 July, 2004. The low N:P values exhibit nitrogen deficiency during the periods of observation. This result is not representative of typical summer environment in the southern coast of Korea. The possible mechanisms are as follows: 1) The freshwater inflow was not sufficient for the supply of nitrogen because the total precipitation was 11.9 mm in July, 2004. This amount is no more than $5\%$ in normal precipitation in July. 2) There was an inflow of oceanic water under the subsurface into the Bottol Bada. Even though the oceanic water comprises more nutrients, it produces the stratification between the surface and the subsurface water and seems to prevent the supply of nutrinets to the surface layer. 3) The high chlorophyll-a concentration of $1.2 {\cal}ug/L$ was shown near the narrow channel between Gae-do and Geumo-do. This seems to be resulted from the inflow of water from Gamak Bay.

• 한국터널지하공간학회 논문집
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• 제19권3호
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• pp.463-473
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• 2017

벤토나이트는 물과 접촉하면 팽창하고 점성을 발휘하는 성질이 있어 일반적으로 차수가 필요한 토목공사에 많이 활용되고 있다. 이수식 TBM에서는 이와 같은 성질을 활용하여 가압된 슬러리로 불투수성 막을 형성하고 굴착벽면의 붕괴를 방지하는 동시에 굴착된 버력을 운송하며 굴착을 수행한다. 하지만 벤토나이트는 해수와 접촉할 경우 팽창성이 저하되어 그 성질을 발휘하지 못하는 문제가 있다. 이는 해수 조건에서 이수식 TBM으로 터널을 굴착할 시 지하수 유입 증가로 인한 굴착 안정성 및 버력 배출에 문제를 초래할 수 있다. 본 연구에서는 이수식 TBM으로 터널을 굴착 시 해수의 유입으로 인한 슬러리의 상태변화를 살펴보고 이에 대응하기 위한 슬러리 관리방안을 제시 하였다. 이를 위해 현장에서 적용된 슬러리 품질관리 기준을 바탕으로 실내 시험을 수행하였으며, 해수의 영향이 있는 현장에 적용 할 수 있는 방안을 제시하였다.

• 한국관개배수논문집
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• 제7권1호
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• pp.8-18
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• 2000

The variations of water quality due to inflow of sea water by gate operation were observed in Sihwa Lake. The distributions and concentration of salinity, temperature, dissolved oxygen, nutrient were investigated from Feb. 1997 to Jul. 1998. The salinity