• Nuclear industry
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• v.14 no.12 s.142
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• pp.30-35
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• 1994

• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.691-698
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• 1997

The risk assessment model for dam and levee is applied to a river where two adjacent dams are located in the upstream of the watershed. "A" dam is proven to be safe with 200-year precipitation and unsafe with PMP condition, whereas "B" dam to be safe with 200-year precipitation and PMP condition. The computed risk considering the uncertainties of the runoff coefficient. initial water depth and relevant data of the dam and spillway turn out to be equivalent results in Monte-Carlo and AFOSM method. In levee risk model, this study addresses the uncertainty of water surface elevation by Manning's equation. Monte-Carlo simulation with the variations of Manning's roughness coefficient is calculated by assuming that it follows atriangular distribution. The model can be used for preparing flood risk maps, flood warning systems, and establishing nation's flood disaster protection plan.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.2B
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• pp.139-147
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• 2012

This study is derived relationships of the resistance coefficients of Darcy-Weisbach and Manning for flow resistance and the dimensionless velocity using many field measurements for 1,875 rivers consist of sand 179, gravel 992, cobble 651 and boulder 53 channels in natural rivers, respectively. The relationships of power law forms are developed as a function of flow discharge, friction slope, and relative submergence by the regression and the semi-empirical method. The measurements distribution of Manning resistance coefficients by the Box-Whisker Plots show the values which ranges from 0.004~0.151 for sand, 0.008~0.250 for gravel, 0.015~0.327 for cobble, 0.023~0.444 for boulder in natural rivers, respectively. Relationships of these semi-empirical and resistance coefficients will be useful to give information in hydraulic engineering.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.637-644
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• 2012

The discharge estimation that means the most important element in a wetlands ecosystem and rivers is a prime concern. All the interim, this discharge estimation depends on stage-discharge curve, but the limitation of stage-discharge curve that uses only connection between the stage and discharge is widely well known. Thus, this paper proposed a method of discharge estimation in a section through "representative parameter estimation method" by using Manning and Chezy equations that have been extensively used in an open channel. Each result is presented by both RMSE and Discrepancy Ratio. The scale difference for the results between laboratory and natural open channel data existed, but the each result showed that the estimated discharge agree with the measured discharge. If the verification and improvement are conducted in various rivers through continuous study, the easy and rapid discharge estimation will be possible. So, the proposed method will be utilized in the water resources fields.

• Journal of Korea Water Resources Association
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• v.46 no.12
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• pp.1209-1220
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• 2013

Roughness coefficients calibrated by flow modeling using the 1-dimensional numerical model were analyzed for the downstream section of Naesung Stream in this study. Also, the bedform configuration at the Hyangseok Station was predicted for measured and simulated hydraulic conditions of flows and total flow roughness was estimated with the coefficient of grain roughness. The Manning's n coefficients calibrated by numerical modeling and estimated by considering of grain and bedform roughness were compared and examined. As a result, the Manning's n by numerical modeling was greater than the coefficient range estimated by grain and bedform roughness at the low flow regime due to the other factors such as vegetation, sinuosity, and sand bar. However, the Manning's n by numerical modeling was included in the coefficient range by grain and bedform roughness at the transition and high flow regime over $500m^3/s$ of flow discharge.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1894-1899
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• 2008

하천 내의 자생수목군에 의한 자연적인 흐름저항의 증가, 식재를 통한 인위적인 흐름저항의 증가, 교각 등의 구조물로 인한 흐름저항을 배수계산에 반영하기 위하여 일반적으로 Manning n값이 사용된다. 그러나 흐름 장애물로 인하여 증가된 Manning n값의 선정은 Chow(1950) 등이 제시한 도표를 활용하는 방법과 같이 공학적 판단을 요하는 작업이다. 그러므로 객관적으로 흐름저항을 산정할 수 있는 기법의 개발이 필요하며, 이를 위한 기초연구로 본 연구에서는 개수로 내 장애물의 항력계수 특성에 대하여 분석하고자 한다. 일반적으로 항력계수는 유체의 유속에 따라 변화되므로, Reynolds 수 또는 Froude 수에 따라 변화되는 것으로 알려져 있다. 그러나 그 범위가 연구자에 따라 상이하여 이를 정량화 할 필요가 있으며, 본 연구에서는 실험자료로부터 개수로 내 장애물의 항력계수 특성을 분석하고, 개수로에서 일반적으로 발생할 수 있는 Reynolds 수 또는 Froude 수 범위에서 기존 연구결과들을 비교분석하여 항력계수의 범위를 정량적으로 정립하고자 한다. 일반적인 상류 흐름조건에서 평균 항력계수($C_D$)는 1.11로 계산되었고, Froude 수의 증가에 따라 항력계수의 변동성이 점차 증가하였으며, 이러한 결과로부터 개수로 내 장애물로 인한 흐름저항을 반영하기 위하여 Manning n값으로 산정된 결과는 평균 0.01의 편차를 보이는 것으로 분석되었다.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.5
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• pp.18-32
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• 1993

A marine engine system (MES) should be evaluated by not only reliability (R) but also maintainability (M) and manning index (MI), because this system can be recognised as a typical man-machine system. In 1977 at the first ICMES Conference in Paris one of the authors presented a total evaluation of the MES with the three indices, R, M, MI, proving the human ability of detecting faults and defects in this system. This paper describes how the MES has developed from the point of view of the above three indices during the past 30 years in Japan and its problems in the future, and arrives at the following conclusions : the reliability of the MES has developed due to quality control (QC) ; the maintainability of the MES has improved due to education and training ; the manning index of the MES has improved due to Rand M ; the availability of the MES has kept constant due to the decreasing complement onboard, at the rate of one person per year approximately ; and two esimations having the three indices were shown by the SRIC 1990 Data Base in Japan, for the two kinds of subsystems in the developed MES.

• Journal of Korea Water Resources Association
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• v.48 no.4
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• pp.291-298
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• 2015

The aim of this study is that a theoretical formula for estimating the one-dimensional longitudinal dispersion coefficient is derived based on a transverse distribution equation for the depth averaged stream-wise velocity in open channel. In "Part I. Theoretical equation for stream-wise velocity" which is the former volume of this article, the velocity distribution equation is derived analytically based on the Shiono-Knight Model (SKM). And then incorporating the velocity distribution equation into a triple integral formula which was proposed by Fischer (1968), the one-dimensional longitudinal dispersion coefficient can be derived theoretically in "Part II. Longitudinal dispersion coefficient" which is the latter volume of this article. SKM has presented an analytical solution to the Navier-Stokes equation to describe the transverse variations, and originally been applied to straight and nearly straight compound channel. In order to use SKM in modeling non-prismatic and meandering channels, the shape of cross-section is regarded as a triangle in this study. The analytical solution for the velocity distribution is verified using Manning's equation and applied to velocity data measured at natural streams. Although the velocity equation developed in this study do not agree well with measured data case by case, the equation has a merit that the velocity distribution can be calculated only using geometric data including Manning's roughness coefficient without any measured velocity data.

• Journal of Navigation and Port Research
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• v.38 no.5
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• pp.527-539
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• 2014

This study establishes the research model and sets up the hypothesis in order to analyze the effect of the type of mixed manning and the ratio of foreign crew on the group cohesiveness, job satisfaction and organizational commitment in ship organizations and the moderating effect of the acceptance and adaptation of cross-culture. For statistical hypothesis testing, it conducts a questionnaire survey targeting mixed manning ships and examines empirically the inter-variables relation through the regression. The result of empirical research is that the group cohesiveness, job satisfaction and organizational commitment in the ship organization of Korean master(chief engineer) and foreign officers is higher than that of Korean master and officers. Moreover, it is found that the group cohesiveness of 31~50% foreign crew group is less than that of the others. However, There is no moderating effects of the acceptance and adaptation of cross-culture. Additionally, it demonstrates the higher job satisfaction and organizational commitment in the stronger cohesiveness groups. The finding suggests the rationale that shipping and ship management companies could raise the group cohesiveness, job satisfaction and organizational commitment by moderating the type of mixed manning and the ratio of foreign crew.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.5
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• pp.613-618
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• 2005

In analysis of pipelines or pipe network we calculated the friction loss using Hazen-Williams or Manning formula approximately, or found one by friction coefficient from Moody diagram graphically. The friction coefficient is determined as a function of relative roughness and Reynolds number. But the calculated friction coefficient by Hazen-Williams or Manning formula considered roughness of pipe or velocity of flow. The friction coefficient in Darcy-Weisbach equation was obtained from the Moody diagram. This method is manual and is not exact from reading. This paper is presented numerical solution of Colebrook-White formula including variables of relative roughness and Reynolds number. The suggested subroutine program by an efficient linear iteration scheme can be applied to any pipe network system.