• Journal of Korea Water Resources Association
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• v.32 no.1
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• pp.31-40
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• 1999

After investigating the basic problems of seepage flow, the friction factor equation of power form was developed for solving them. The use of power law for the estimation on friction factor enabled to develop the explicit form of equations without any iteration process being related to various non-dimensional physical numbers. For the derivation of friction factor equations, the existing data were re-analyzed, and the simple method of seepage flow design was devised with the power law equations for the estimation of slope, discharge, and diameter.

• Journal of Korea Water Resources Association
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• v.38 no.7 s.156
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• pp.527-535
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• 2005

The computation of normal depth is very important for the design of channel and the analysis of water flow. Drainage pipe generally has the shape of curvature like circular or U-type, which is different from artificial triangular or rectangular channel. In this case, the computation of normal depth or the derivation of equations is very difficult because the change of hydraulic radius and area versus depth is not simple. If the ratio of the area to the diameter, or the hydraulic radius to the diameter of pipe is expressed as the water depth to the diameter of pipe by power law, however, the process of computing normal depth becomes relatively simple, and explicit equations can be obtained. In the present study, developed are the explicit normal depth equations for circular and U-type pipes, and the normal depth equation associated with Hagen (Manning) equation and friction factor equation of smooth turbulent flow by power law is also proposed because of its wide usage in engineering design.

• Journal of Korea Water Resources Association
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• v.32 no.4
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• pp.469-478
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• 1999

Explicit equations of minimum velocity, energy slope and pipe diameter are developed to ensure the cleaning of sewerage pipes. The equations of power form are employed for the estimation of critical shear stress of sediment particles and the friction factor of commercial pipes. They are all based on the existing laboratory data. Several cases are tested to check the values suggested in the manual, using the equations developed in the present study.

• Journal of Korea Water Resources Association
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• v.35 no.6
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• pp.729-736
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• 2002

The computation of normal depth is one of the most important parts in the design of open channel flow, and the best section is in general the most economic section in the case of constructing artificial open channels. Thus the determination of the normal depth of the best section is the essential item in the design of most open channel flows. To estimate the frictional forces a power law is introduced, which is applicable to most situations in open channel flows. Explicit and consistent forms of equations are deduced for the calculation of normal depth of triangular, rectangular and trapezoidal best sections. Furthermore the equations of normal depth are found to have the same form as those of pipe diameter for the design of pipe flow.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1775-1780
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• 2009

개수로 마찰흐름 특성에 관한 연구로서 유량조사사업단(2006)의 우리나라 3대강 유역 하천 관측자료와 Jarrett(1984)의 미국 Colorado지역 하천의 관측자료로 부터 흐름특성을 구분하여 개수로 흐름의 마찰특성 또는 조도계수의 변이특성을 분석하였다. 기존 지수형 완난류 마찰계수 산정식(유동훈과 이민호,1997)의 비례상수 $\alpha$에 조도계수 n을 도입하여 실무에서 보다 편하게 적용할 수 있는 새로운 산정식을 개발하였다. 유량조사사업단의 관측자료 분석에 있어서 유량 관측시 관측지점의 수면경사 및 하상경사의 미관측으로 하천정비기본계획상에 제시된 지형으로부터 관측지점의 하상경사를 추정하였으며 1차적으로 에너지경사는 하상경사와 동일하다고 가정하였다. 이러한 가정하에 하천정비기본계획상에 제시된 Manning의 조도계수를 인용하여 관측유속과 계산유속을 비교8 분석하였다. 또한 전통적 산정식인 Ganguillet & Kutter(1869)식과 Manning(1889)식으로 부터 산정된 유속과의 비교를 통하여 조도계수 n을 추정하였고 추정된n을 도입하여 새로 개발된 지수형 마찰계수 산정식의 적용성을 입증하였을 뿐만 아니라 기존 조도계수 산정의 문제점을 제시하였다.

• Journal of Korea Water Resources Association
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• v.34 no.1
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• pp.31-43
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• 2001

The friction factor of commercial pipe varies with wide range depending on pipe type and pipe size. Various methods can describe the wide variation of friction factor with good accuracy, but they normally require an iteration process even for solution of a simple case. Power law can result in an explicit form of solver so that the power law is rigorously employed for the development of direct solution technique. The parameters used in the present form of power law are allowed to haute some variation with pipe size and Reynolds number as well as pipe type for wider coverage with good accuracy, while Hazen-Williams equation permits limited variation which accounts only for the roughness or the pipe type. Furthermore secondary loss is considered in the development of explicit equations for design of commercial pipes.

• Journal of Korea Water Resources Association
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• v.31 no.5
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• pp.565-574
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• 1998

The friction factor distribution of commercial pipes vary according to the pipe type and size. The present paper developed the friction factor equations of power law by analyzing the data reported by Colebrook(1938). Generally, pipe design requires pump power, discharge or pipe diameter for each condition given. Yoo(1995b) has suggested the basic equations for the explicit design of uniformly rough pipe and Yoo and Kang(1996) have refined those equations for the cases of uniformly rough pipe on a sloping bed with a pumping power. Furthermore Yoo and Kang(1997) have studied the design of commercial pipe for a general case. The approach gives relatively accurate solutions, but the equations obtained are rather complicated. In the present study two types of power law are developed for the friction factor of commercial pipe, and explicit forms of equations are generated by applying the power law friction factor equations for the simple design of commercial pipes.

• Journal of Korea Water Resources Association
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• v.36 no.1
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• pp.87-104
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• 2003

A numerical model of surface runoff and river flow has been applied to small- and large-size catchment areas in order to investigate the physical characteristics of river flow during flood period. Several refinements are made on the existing model SIRG-RS for the ways of rainfall input through surface runoff, river junction treatment and the computation of river flow on steep slope. For the computation of frictional forces, employed is the power law of friction factor which is a function of Reynolds number and relative roughness height. The empirical equation of friction factor is developed using recent field data as well as laboratory data. The refined model has been applied to small-size catchment area as well as large-size catchment area, and the computation results are found in good agreement with the observations in both cases.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.307-307
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• 2011

ARF(Areal Reduction Factor, 면적우량감소계수)는 지점강우량을 면적 평균 강우량으로 변환하는 환산계수로 정의되며, 유역의 지형학적 특성과 강우의 공간적 분포특성을 반영한 유역단위의 ARF의 개발이 요구된다. 하지만 국내의 ARF는 대부분 한강유역을 대상으로 하고 있어 한강유역과 지형학적, 수문 기상학적 특징이 상이한 유역에 대하여 연구 결과를 적용하기는 많은 제약이 따를 것으로 판단된다. 따라서 본 연구에서는 남강댐 유역의 ARF를 산정하기 위해 7개의 강우관측소(산청, 삼가, 신안, 안의, 운봉, 태수, 함양)로부터 시강우자료(1990년~2010년)를 수집한 후 14개의 재현기간, 6개의 지속시간에 대한 지수형 ARF 회귀식을 산정하였다. 그 결과 남강댐 유역의 지수형 ARF 회귀식의 결정계수는 0.80~0.99로 높은 상관성을 나타내었다. 그리고 남강댐 유역의 ARF와 첨두홍수량의 관계를 분석하기 위해 남강댐 유역내의 산청유역을 대상으로 재현기간 100년, 지속시간 24시간에 대한 홍수량을 모의하였다. 그 결과 ARF의 적용 전 후의 첨두홍수량은 10% 이상 감소하는 것으로 나타났다. 따라서 남강댐 유역의 기상학적 특성을 고려한 첨두홍수량 산정을 위해서는 본 연구에서 제안한 ARF 회귀식이 유용할 것으로 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.367-372
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• 2008

본 연구는 감조하천에서 조위의 영향을 크게 받는 저 평수위의 수위-유량관계곡선식 개발의 한계를 극복하기 위해 조위의 영향을 고려한 다변수 복합 수위-유량관계곡선식을 개발하였다. 곡선식 개발은 수위-수면차-수위차-유량의 관계를 통해 지수형 곡선식을 개발하였다. 여기서 수면차는 조위와 수위와의 차이며, 이때 조석파의 전파시간에 대한 지체시간을 고려하였다. 수위차는 대상 수위관측소의 전 시간과의 수위차이다. 또한 조위에 의해 발생되는 역유량 자료를 이용한 지수형 곡선식을 개발하고자 유량 조정변수를 추가하였다. 개발된 수위-유량관계곡선식을 한강대교에 적용하여 자동유량측정시설에서 측정된 유량자료와 비교 검토한 결과 경향성에서 일치하였으며, (-)유량의 산정도 가능하였다. 분석기간내의 총 유출량 검토 결과 8.3%의 오차를 보여 본 과업에서 제시된 복합 수위-유량관계곡선식의 적정성을 파악할 수 있었다.