• 한국환경과학회지
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• 제21권4호
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• pp.471-478
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• 2012

In this study, the flow characteristic analysis at the curved-channel of the actual channel section is compared and reviewed using the 2D RMA-2 model and the 3D FLOW-3D model. the curve section with curve rate 1.044 in the research section is analyzed applying the frequency of he project flood of 100 years. According to the result, the issue for the application of the FLOW-3D Model's three-dimensional numeric analysis result to the actual river is found to be reviewed with caution. Also, application of the 3D model to the wide basin's flood characteristic is determined to be somewhat risky. But, the applicability to the hydraulic property analysis of a partial channel section and the impact analysis and forecast of hydraulic structure is presumed to be high. In addition, if the parameters to reflect the vegetation of basin and the actual channel, more accurate topological measurement data and the topological data with high closeness to the current status are provided, the result with higher reliability is considered to be drawn.

• 대한토목학회논문집
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• 제36권3호
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• pp.427-437
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• 2016

본 연구에서는 지형 및 기상학적 인자만으로 미계측 유역의 저유량부 유황곡선을 추정할 수 있는 지역회귀모형을 개발하고자 하였다. 이를 위해서 16개 유역의 계측 자료로부터 저유량 영역(지속일수 185일에서 365일)에 대한 유황곡선을 작성하고, 이를 토대로 로그형태의 이변수 회귀모형을 구축하였다. 이 회귀모형을 미계측 유역에 적용할 수 있도록 유역면적, 유역경사, 수계밀도, 연평균강수량, 연평균유출량, 유출곡선지수 등의 유역특성인자를 이용하여 모형의 매개변수를 지역화 하였다. 개발한 지역회귀모형으로 평균갈수량, 평균저수량, 평균평수량을 추정하여 관측값과 비교한 결과, 유역면적, 유출곡선지수, 연평균강수량 조합으로 구성된 지역회귀모형이 가장 우수한 것으로 분석되었다.

• 대한환경공학회지
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• 제32권9호
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• pp.830-839
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• 2010

본 연구에서는 현재 시행되고 있는 오염총량관리제 모니터링 시스템에 적용가능한 부하량 추정기법에 대하여 제시하였다. 수정 TANK 모형을 통하여 8일 간격 유량자료의 1일 간격 유량자료로의 확장을 시행하여 유황곡선의 작성을 가능하게 하였다. 7변수 대수 선형 모형 적용 통한 BOD, COD 및 TOC 부하량 추정에서 만족스러운 결과를 확인할 수 있었다. 연구의 적용의 일환으로, 낙동강유역의 BOD, COD 및 TOC 항목의 부하량 유황 곡선을 작성하여 전체적인 분포를 살펴보았다. 본 연구를 통하여 파악된 부하량 유황곡선은 해당 지점의 현재 전체적인 수질현황을 확률적으로 파악할 수 있음과 동시에 이를 시각적으로 도시할 수 있는 장점을 가지고 있다.

• 한국방재학회 논문집
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• 제3권2호
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• pp.119-125
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• 2003

불포화토에서 물의 흐름은 함수비 특성곡선과 투수계수 특성곡선(permeability-suction relation ship)이라 불리우는 두 방정식에 의해서 영향 받는다. 함수비 특성곡선은 체적함수비와 석션(suction)간의 관계를 나타내는 방정식이다. 많은 연구자들은 특성곡선식들을 제시해 왔다. 이 논문은 불포화토에서 물의 흐름을 분석할 때 특성곡선식들을 정확하게 결정하는 것이 중요하다는 것을 보여준다. 비교목적을 위해서 두 방법 즉, Gardner (1958)에 의해서 제시된 특성곡선식들과 Fredlund (1994) 의해서 제시된 특성곡선식들이 사용된다. 이 두 방법을 사용하여 유한요소법에 의한 물 흐름의 수치해석이 수행된다. 수치해석 결과들은 미 Ohio주 Delaware County에 있는 TDR (Time-domain reflectometry) 계측기로부터 얻어진 현장 데이터와 비교된다. 이 데이터는 전략적 고속도로 연구 프로그램(Strategic Highway Research Program)의 한 부분으로 포함된 계절 계측 프로그램(Seasonal Instrumentation Program)에 의해 얻어졌다.

• 한국물환경학회지
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• 제29권6호
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• pp.762-776
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• 2013

Load duration curve was applied to determine important water quality parameter control term for improvement of Paldang lake water quality. Load duration curve was analyzed with long term data from 1985 to 2012 including water quality, flow rate and climate state of Paldang water environment. From the result of flow rate patterns of paldang lake, differences between high and low flow rate of each year showed tendency of increase because rainfall characteristics of paldang lake watershed were changed by climate exchange. Both of land use state of upper Paldang lake watershed and number of limit excess from load duration curve indicated that seasonal action related with land use such as agricultural fertilizer distribution in upper watershed affected Paldang lake water quality. So focused BOD (biological oxygen demand) management during spring season from march to June is required to control organic materials in Paldand lake. The main affecting factor of TOC (total organic carbon) increase in Paldang lake was initial rainfall after march. T-N (total nitrogen) kept increasing during research period, so enhancement of T-N standard is needed to T-N control. Initial rainfall and increase of temperature during spring season from March to June showed a positive correlation with TP (total phosphorus) and Chl-a, respectively.

• 한국환경과학회지
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• 제28권10호
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• pp.873-885
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• 2019

In this study, a load duration curve was applied to the Jangseongcheon, one of the tributaries of the Yeongsan River, to assess whether the target water quality was achieved. In addition, pollution of the water body was investigated to develop and suggest the optimal management time with respect to polluted flow sections and monthly conditions. The average flow rates of sections JS1 and JS2 were $0.25m^3/s$ and $1.08m^3/s$, respectively. The BOD and T-P for water-quality standards at JS1 were rated at II, whereas the COD and TOC were rated at III, thus indicating a fair level of water quality. By contrast, the BOD at JS2 was rated at III, the T-P at IV, and the TOC at V, indicating poor water quality in this section. The load duration curve was plotted using the actual flow data measured in eight-day intervals for eight years from 2011 to 2018 at locations JS1 and JS2 in the Jangsungcheon Basin. In an assessment using the load duration curve on whether the target water quality was met at location JS1, all of the water quality parameters (BOD, COD, TOC, T-N, T-P, and SS) satisfied the target water quality. By contrast, at location JS2, parameters COD, TOC, T-N, and T-P exceeded target values by more than 50%, indicating the target water quality was not met. The discharge loads of locations JS1 and JS2 were analyzed to identify the reasons the target water quality was exceeded. Results revealed that the land system contributed considerably. Furthermore, the discharge load of JS2 accounted for more than 80% of the load on the entire basin, excluding that of JS1. Therefore, the best method for restraining the inflow of pollutants into the stream near location JS2 must be applied to manage the water quality of the Jangsungcheon.

• 한국물환경학회지
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• 제35권6호
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• pp.481-496
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• 2019

The Ministry of Environment has measured streamflow at eight-day intervals for the estimation of standard flow of the Total Maximum Daily Loads (TMDL) system. This study identified the availability of the partially measured the eight-day interval data for estimating standard flow and found the optimal extension techniques of standard flow. The study area was selected for the Nakbon-A watershed in the Nakdong River, and four streamflow record extension techniques of standard flow were considered: extension, percentile, drainagearea, and regional regression methods. The flow duration curve (FDC) using the eight-day interval streamflow data indicated very high Nash and Sutcliffe Efficiency (NSE) values above 90 % from FDC-II to FDC-VII compared to FDC-VIII, the standard FDC. This result demonstrates that FDC using daily data of three-six cumulative years could represent standard FDC fairly well. For the streamflow record extension techniques of standard flow, the percentile method was selected as the optimal alternative, showing the minimal difference from FDC-VIII. These results validate the availability of the eight-day interval streamflow data in the standard flow estimation and the application of extension techniques. It seems that these results could reduce the uncertainty of partially measured streamflow data for water quantity and quality management.

• 한국지반환경공학회 논문집
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• 제18권1호
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• pp.13-21
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• 2017

본 연구에서는 최근 10년 동안 강원도 영서와 인접지역에서 토석류가 발생한 지역에 대해 현장조사를 실시하고 강우자료를 수집하여 구축한 D/B를 바탕으로 토석류의 거동 및 강우특성을 조사하였다. 사면형과 계곡형의 토석류 종류에 따라 발생부, 유하부, 퇴적부로 구별되는 토석류 진행구간에 대해 토석류 거동특성을 분석하였으며 발생부 및 유하부의 침식 상태를 고려하여 토석류 규모를 산정하였다. 토석류 발생 당시의 강우자료 분석을 통해 토석류 유발 강우 기준에 대한 선행연구와 비교 분석하여 예경보 기준 정립에 고려할 사항을 제시하였다. 또한, 조사지역에 적합한 토석류 유발강우 ID 곡선을 제안하여 기존의 연구결과와 비교 분석하였다.

• International Journal of Fluid Machinery and Systems
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• 제8권1호
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• pp.46-54
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• 2015

Thrust-ring-pump is a kind of extreme-low specific speed centrifugal pump with special structure as numerous restrictions from thrust bearing and operation conditions of hydro-generator units. Because the oil circulatory and cooling system with thrust-ring-pump has a lot of advantages in maintenance and compactness in structure, it has widely been used in large and medium-sized hydro-generator units. Since the diameter and the speed of the thrust ring is limited by the generator set, the matching relationship between the flow passage inside the thrust ring (equivalent to impeller) and oil bath (equivalent to volute) has great influence on hydrodynamic performance of thrust-ring-pump. On another hand, the head and flow rate are varying with the operation conditions of hydro-generator units and the oil circulatory and cooling system. As so far, the empirical calculation method is employed during the actual engineering design, in order to guarantee the operating performance of the oil circulatory and cooling system with thrust-ring-pump at different conditions, a collaborative hydrodynamic design and optimization is purposed in this paper. Firstly, the head and flow rate at different conditions are decided by 1D flow numerical simulation of the oil circulatory and cooling system. Secondly, the flow passages of thrust-ring-pump are empirically designed under the restrictions of diameter and the speed of the thrust ring according to the head and flow rate from the simulation. Thirdly, the flow passage geometry matching optimization between thrust ring and oil bath is implemented by means of 3D flow simulation and performance prediction. Then, the pumps and the oil circulatory and cooling system are collaborative hydrodynamic optimized with predicted head-flow rate curve and the efficiency-flow rate curve of thrust-ring-pump. The presented methodology has been adopted by DFEM in design process of thrust-ring-pump and it shown can effectively improve the performance of whole system.

• 한국지리정보학회지
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• 제23권3호
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• pp.174-191
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• 2020

본 연구에서는 대청호 상류에 있는 서화천 유역에서 부하지속곡선을 통한 소유역별 비점오염원 취약지역 및 관리 오염물질과 관리 시기를 분석하였다. 먼저 부하지속곡선을 만들기 위하여 장기 유출 모형인 SWAT를 구축하여 유량지속곡선(Flow Duration Curve)을 작성하였으며 그 결과에 목표 수질을 곱하여 부하지속곡선(Load Duration Curve)을 작성하였다. 목표 수질은 서화천 비점오염원 관리를 위해 지난 2017년 11월부터 측정한 모니터링 자료를 사용하였으며 측정자료의 60분위에 해당하는 값을 목표 수질로 설정하였다. 이때 산정된 값이 하천 생활환경 기준의 "약간좋음"(II)을 초과할 경우 목표 수질을 "약간 좋음"(II)으로 제한하였다. 비점오염원 취약지역은 목표 수질을 초과하는 초과율을 이용하여 선정하였으며 초과 되는 오염물질을 관리 물질로 판단하고 계절별 평가를 통해 관리시기를 선정하였다.