• Water Engineering Research
• /
• 제1권1호
• /
• pp.25-37
• /
• 2000

This study presents some results of a preliminary study for the coupled precipitation and river flow prediction system. The model system in based on three numerical models, Mesoscale Atmospheric Simulation model for generating atmospheric variables. Soil-Plant-Snow model for computing interactions within soil-canopy-snow system as well as the energy and water exchange between the atmosphere and underlying surfaces, and TOPMODEL for simulating stream flow, subsurface flow, and water tabled depth in an watershed. The selected study area is the 2,703 $\alpha_4$ $\km_2$ Soyang River basin with outlet at Soyang dam site. In addition to providing the results of rainfall and stream flow predictions, some results of DEM and GIS application are presented. It is obvious that the accurate river flow predictions are highly dependant on the accurate predictation predictions.

• 물과 미래
• /
• 제35권5호
• /
• pp.51-59
• /
• 2002

In recent years the human impact on the environment becomes increasing lift threatening, calls for the better management of resources. In field of water quality of river flow, the best way to conserve water quality is specific efforts to control the pollutant loadings and treat the loadings in the basin to reduce the discharge of pollutant loadings to river. But in general the water quality influenced by the dam discharge. Especially in dry season, it is more dominant way to improve the water quality which contaminated with the pollutant loadings from the basin. The dam discharge amounts of the 2 dams in the Keum River that maintain the down stream water quality were estimated for the year of 1999, 2001, 2006, 2011, in case of irrigation and non-irrigation seasons. The pollutant loadings for the basin are estimated with the planning of treatment plants construction schedule for every sub-basins. The river flow rates were considered low flow as 2.33 year low flow and 10 year low flow. The QUAL2E model was used as a tool of simulation.

• 산업기술연구
• /
• 제29권B호
• /
• pp.215-219
• /
• 2009

Based on the data interpretation on an artificial marsh built in Chun-cheon Lake, the study analyzed flow characteristics and found that flow was unstable due to sediment of natural river but the effect of artificial marsh was similar with that of river improvement works. Flow velocity in the section of artificial marsh was found to be 1m/sec. Therefore flow velocity was stable, which could contribute to improving water quality. A flow velocity as well as stream vector was improved.

• Journal of Advanced Marine Engineering and Technology
• /
• 제39권5호
• /
• pp.548-553
• /
• 2015

The conventional ejector-diffuser system makes use of high pressure primary stream to propel the secondary stream through pure shear action for the purposes of transport or compression of fluid. It has been widely used in many industrial applications such as seawater desalination, solar refrigeration, marine engineering, etc. The present study is performed numerically to study the performance of a two-stage ejector-diffuser system. The detailed flow phenomenon of the ejector-diffuser system has been critically predicted by means of the numerical approach using compressible Reynolds averaged Navier-Stokes (RANS) equations. The axi-symmetric supersonic ejector-diffuser flow has been solved by a fully implicit finite volume scheme with a two-equation k-omega turbulence model. The numerical results are validated with existing experimental data. Detailed flow physics and their contributions on ejector performance are detected to compare both single-stage and two-stage ejectors. The performance improvement on the ejector-diffuser system is discussed in terms of the mass flux ratio and the coefficient of power.

• 대한토목학회논문집
• /
• 제4권1호
• /
• pp.49-58
• /
• 1984

충적하천(沖積河川)에서 정류(定流), 부정류(不定流) 상태에서의 퇴적물 이동현상(移動現象)과 점변류(漸變流) 상태에서의 유사이동(流砂移動)에 대한 수치해석방법(數値解析方法)을 제시(提示)하였다. 충적하천(沖積河川)의 점변류(漸變流) 상태 및 토사이동현상(土砂移動現象)은 상당히 복잡한 물리현상(物理現象)으로 이 때문에 이에 관련된 수학적(數學的)인 모델의 설정이 필요(必要)하다. 유사이동(流砂移動)에 대하여, 종전(從前)에 이용한 정류개념(定流槪念)보다는 수치해석방법(數値解析方法)으로 수정간접법(修正間接法)의 선형완전음해법(線形完全陰解法)을 적용(適用)함으로서 실제현상(實際現象)과의 오차(誤差)를 줄일 수 있다. 더나아가 충적하천(沖積河川)에 있어서 점변류(漸變流)의 개념을 발전(發展)시켜 수치해석(數値解析)의 정도(精度)를 높이고 실용화(實用化)함으로서 하상변동(河床變動)을 합리적(合理的)으로 예측(豫測)할 수 있을 것으로 기대(期待)된다.

• 한국물환경학회지
• /
• 제28권4호
• /
• pp.538-550
• /
• 2012

This study suggests a general methodology which is designed for assessing RDOC behavior at the catchment scale by coupling properly a series of steam flow and water quality simulation models and actual monitoring data set. The modified TANK model in which a river routing function is incorporated to the conventional one is applied to simulate the long-term daily stream flow data, and the simulated stream flow data is combined with the 7-parameter log-linear model coupled to the minimum variance unbiased estimator to simulate the long-term daily water quality (BOD, COD and TOC) loads. Finally, the regression analysis between the usually monitored water quality data (BOD, COD and TOC) and RDOC is combined with the simulated water quality data to manifest the spatio-temporal variability of RDOC flux behavior at the Korean TMDL catchment scale.

• 대한기계학회논문집
• /
• 제16권4호
• /
• pp.775-786
• /
• 1992

본 연구에서는 DVM의 이론적 배경과 수치계산에 대해 자세히 다루었다. 음향 교란이 가졌을 때의 재부착에 대한 수치해석결과는 Kiya등의 실험결과와 비교하 였으며 만족할만한 일치를 보여주었다. 결과 및 고찰에서는 주로 음향교란이 있는 경우의 재부착길이를 최소화하는 주파수와 교란이 없는 유동의 난류구조해석을 평균속 도 및 압력과 그의 섭동치, 그리고 파워 스펙트럼과 상관계수등을 통해 자세히 비교검 토하였다.

• 한국환경과학회지
• /
• 제24권4호
• /
• pp.393-401
• /
• 2015

Rainfall-runoff model of Jeju Oedo Stream was used to compute the optimal unit hydrograph by HEC-HMS model that reflecting on watershed characteristics. Each rainfall event was comparatively analyzed with the actual flow measurement using Clark, Snyder and SCS synthetic methods for derived unit hydrograph. Subsequently, the null hypothesis was established as p-value for peak flow and peak time of each unit hydrograph by one-way ANOVA(Analysis of variance) was larger than significance level of 0.05. There was no significant difference in peak flow and peak time between different methods of unit hydrograph. As a result of comparing error rate with actual flow measurement data, Clark synthetic unit graph best reflected in Oedo Stream as compared to other methods, and error rate of Clark unit hydrograph was 0.02~1.93% and error rate at peak time was 0~2.74%.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2018년도 학술발표회
• /
• pp.493-493
• /
• 2018

The purpose of this study was to analyze the correlation between the effluent of the sewage treatment plant (STP) and the adjacent stream located downstream of the STP in Nakdong River. The flow and water quality such as BOD, COD, SS, T-N, and T-P data for 12 STPs and adjacent downstream monitoring stations in the main stream and tributaries of Nakdong River were collected from 2012 to 2015. As a result of correlation analysis between river flow and water quality at the river water quality measurement point, COD, SS and T-P were correlated positively with river flow rate at 6, 8, and 6 points, respectively. As a result of analyzing the water quality of sewage treatment plant effluent and downstream stream, BOD and COD were correlated at 2 and 3 points, respectively. T-N showed a positive correlation at 9 points, and 7 of them had a strong positive correlation, indicating that sewage treatment effluent had a large effect on downstream streams. In this study, we found that the correlation between river flow rate and water quality factors (COD, SS, TP) was high for river water measurement points, and the sewage treatment plant effluent was correlated with the T-N value of adjacent streams.

• 한국물환경학회지
• /
• 제20권2호
• /
• pp.151-156
• /
• 2004

A decision support system, Watershed Analysis Risk Management Framework(WARMF), was applied to the Kyungan Stream watershed, a tributary of Lake Paldang, for calculation of total maximum daily loads(TMDL). The WARMF system was developed by Systech Engineering, USA, and has been successfully used in several watersheds, for TMDL studies. The study area was divided into 14 sub-basins, based on digital elevation model(DEM). The integrated watershed and stream model of WARMF was validated by flow and BOD data measured during the year of 1999. There were reasonable agreements between model results and field data, both in water flow and BOD. The validated Kyungan WARMF was extensively utilized to study the quantitative relationship between waste loads and receiving water quality. Based on TMDL guideline at Paldang Lake and Kyungan Stream, the water quality criterion were set to be 3.0mg/L, 3.5mg/L, and 4.0mg/L at the watershed outlet. The allowable waste loads of BOD, both from point and non-point sources, were determined at each water quality criterion. From this study, it was concluded that the WARMF provided several advantages over the conventional application of watershed and stream models for TMDL study, such as time variable simulations, multiple possible soutions, and reduction loads for goal water quality, etc.