• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 춘계학술대회 논문집
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• pp.70-75
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• 2001

Intensive experimental investigations were carried out to provide information of the effects of inflow on the rolling characteristics and stability of ships, which becomes great concern in relation to ship's capsizing. A series of systematic experiments have been performed considering the effects cf combined motion of roll-heave-sway and relevant parameters, such as roll angle and period, tank water height etc. To accommodate this type of experiments with 3-degree of freedom of motion, a bench tester has been developed and verified using existing data. Also, theoretical application of anti-roll tank has been incorporated to support the process of investigation. A model of Ro-Ro ships is used in the present study as this type of vessels, as well as fishing vessels, with large open decks, can loose stability rapidly when there is inflow on the decks.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1998년도 학술발표회 발표논문집
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• pp.87-91
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• 1998

Unused irrigation water due to delivery losses and overflow from paddies in an irrigation system, and groundwater releases from infiltration are eventually returned to stream. The estimate of irrigation returnflow is important to streamflow modeling and water resources planning. This study was to field monitor the irrigation water use, streamflow, lateral inflow and ground water level, and to determine the return flow of irrigation water

• 한국농공학회논문집
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• 제59권6호
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• pp.9-18
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• 2017

The objective of this study was to estimate the climate change impact on inflow to Namgang Dam using SWAT (Soil and Water Assessment Tool) model. The SWAT model was calibrated and validated using observed flow data from 2003 to 2014 for the study watershed. The $R^2$ (Determination Coefficient), RMSE (Root Mean Square Error), NSE (Nash-Sutcliffe efficiency coefficient), and RMAE (Relative Mean Absolute Error) were used to evaluate the model performance. Calibration results showed that the annual mean inflow were within ${\pm}5%$ error compared to the observed. $R^2$ were ranged 0.61~0.87, RMSE were 1.37~7.00 mm/day, NSE were 0.47~0.83, and RMAE were 0.25~0.73 mm/day for daily runoff, respectively. Climate change scenarios were obtained from the HadGEM3-RA. The quantile mapping method was adopted to correct bias that is inherent in the climate change scenarios. Based on the climate change scenarios, calibrated SWAT model simulates the future inflow and evapotranspiration for the study watershed. The expected future inflow to Namgang dam using RCP 4.5 is increasing by 4.8 % and RCP 8.5 is increasing by 19.0 %, respectively. The expected future evapotranspiration for Namgang dam watershed using RCP 4.5 is decreasing by 6.7 % and RCP 8.5 is decreasing by 0.7 %, respectively.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 1997년도 학술발표회 논문집
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• pp.409-413
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• 1997

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회(1)
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• pp.326-327
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• 2005

• 대한토목학회논문집
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• 제32권6B호
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• pp.363-371
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• 2012

본 연구에서는 댐의 상시보장유량 설정에 기준이 되는 갈수량을 산정하기 위하여 화천댐과 춘천댐의 유입량 자료를 구축한 후 적합도 검정을 실시하여 적정확률분포형을 선정하였다. 또한 선정된 적정확률분포형에 대하여 재현기간에 따른 월별 유입량 계열로 산정한 갈수빈도해석 방법(case 1)과 월단위 누가유입량 계열의 차로 산정한 갈수빈도해석 방법(case 2)을 수행하였다. 본 연구를 통해 한강유역의 상류댐인 화천댐과 춘천댐의 통계적 특성을 반영한 월별 재현기간에 따른 유입량은 홍수기에 제한수위를 설정하는 것과 같은 형식으로 댐의 상시보장유량을 보장하는 저수위를 설정하거나 이수용량을 결정하는데 활용될 수 있을 것으로 판단된다.

• 한국농공학회논문집
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• 제61권1호
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• pp.21-29
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• 2019

This study analyzed the variability of drought risk based on trend analysis of dry-seasonal dam inflow located in upper river basins. To this, we used areal averaged precipitation and dam inflow of three upper river dams such as Soyang dam, Chungju dam, and Andong dam. We employed Mann-Kendall trend analysis and change point detection method to identify the significant trends and changing point in time series. Our results showed that significant decreasing trends (95% confidence interval) in dry-seasonal runoff rates (= dam inflow/precipitation) in three-dam basins. We investigated potential causes of decreasing runoff rates trends using changes in potential evapotranspiration (PET) and precipitation indices. However, there were no clear relation among changes in runoff rates, PET, and precipitation indices. Runoff rate reduction in the three dams may increase the risk of dam operational management and long-term water resource planning. Therefore, it will be necessary to perform a multilateral analysis to better understand decreasing runoff rates.

• Journal of Advanced Marine Engineering and Technology
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• 제38권9호
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• pp.1101-1105
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• 2014

해양온도차발전은 해양의 따뜻한 표층수와 차가운 심층수의 온도차를 발전에 이용하는 전도유망한 기술이다. 지속가능한 온도차를 이용하여 온실가스감축기술로서 활용할 수 있다는 장점을 가지는 반면, 시스템의 효율이 낮다는 단점을 가진다. 해양온도차발전의 낮은 시스템 효율을 개선하기 위해서는 성능이 우수한 터빈의 설계 및 개발기술의 확보가 필요하다. 이에 따라 본 연구에서는 R32를 이용한 100kW급 해양온도차발전용 반경류터빈을 설계하였으며, CFD 해석을 통해 설계한 터빈의 성능을 검증하였다. CFD 해석결과를 참고하여 설계한 반경류터빈의 형상을 수정하였으며 이러한 과정을 반복하여 설계요구조건에 적합한 해양온도차발전용 반경류터빈의 최종 형상을 도출하였다.

• Wind and Structures
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• 제20권4호
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• pp.579-607
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• 2015

A Combination Random Flow Generation (CRFG) technique for obtaining the fluctuating inflow boundary conditions for Large Eddy Simulation (LES) is proposed. The CRFG technique was developed by combining the typical RFG technique with a novel calculation of k and ${\varepsilon}$ to estimate the length- and time-scales (l, ${\tau}$) of the target fluctuating turbulence field used as the inflow boundary conditions. Through comparatively analyzing the CRFG technique and other existing numerical/experimental results, the CRFG technique was verified for the generation of turbulent wind velocity fields with prescribed turbulent statistics. Using the turbulent velocity fluctuations generated by the CRFG technique, a series of LESs were conducted to investigate the wind flow around S-, R-, L- and U-shaped building models. As the pressures of the models were also measured in wind tunnel tests, the validity of the LES, and the effectiveness of the inflow boundary generated by the CRFG techniques were evaluated through comparing the simulation results to the wind tunnel measurements. The comparison showed that the LES accurately and reliably simulates the wind-induced pressure distributions on the building surfaces, which indirectly validates the CRFG technique in generating realistic fluctuating wind velocities for use in the LES. In addition to the pressure distribution, the LES results were investigated in terms of wind velocity profiles around the building models to reveal the wind flow dynamics around bluff bodies. The LES results quantitatively showed the decay of the bluff body influence when the flow moves away from the building model.

• 한국수자원학회논문집
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• 제48권1호
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• pp.69-78
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• 2015

본 연구는 기상학적 가뭄지수가 수문학적 가뭄에 대한 모사정도를 검토하였다. 기상학적 가뭄지수 중에서 강수량을 변수로 하는 SPI(Standardized Precipitation Index)와 강수량 및 증발산량을 변수로 하는 SPEI(Standardized Precipitation Evapotranspiration Index)를 이용하였고, 수문학적 가뭄 평가를 위하여 월 총 유입량과 하천수 가뭄지수인 SDI(Streamflow Drought Index)를 계산하여, 최종적으로 기상학적 가뭄지수와 수문학적 가뭄지수와의 상관정도를 분석하였다. 월별 상관계수 비교결과, 지속기간 270일에 기상학적 가뭄지수와 월 총 유입량과 상관정도가 가장 높아서 0.67로 나타났고 기상학적 가뭄지수로 SDI와의 상관정도는 0.72~0.87이었다. 연별 극한값을 비교한 결과, 월 총 유입량의 최저값과 기상학적 가뭄지수의 연관성은 거의 확인되지 않았다. 다만 SDI와 SPEI가 매우 높은 상관정도를 보였다. 기상학적 가뭄지수로 수문학적 극한가뭄에 해석하는 데에 한계가 있는 만큼 수문 가뭄해석이 목적이라면 유량자료가 직접 활용될 수 있는 가뭄지수가 필요하다.