• Water for future
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• v.29 no.5
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• pp.161-172
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• 1996

Studied are the existing equations of Hazen-Williams and Colebrook-White, and the equations of Yoo's (1995) mean zero velocity point and mean friction factor developed for the estimation of commercial pipe friction factor. Simple arrangements of pipe network are devised by changing the diameter, flow discharge and length, and the characteristics of four equations are investigated by comparing the computed results of pressures at each node. Three groups of pipe diameter, small, medium, large, are considered in the comparison, and various problems of existing equations are discussed based on the computed results of pressures and velocities.

• Korean Journal of Agricultural Science
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• v.47 no.3
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• pp.509-517
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• 2020

Geographic information system (GIS) sewer network data are a fundamental input material for urban inundation modeling, which is important to reduce the increasing damages from urban inundation due to climate change. However, the essential attributes of the data built by a local government are often missing because the purpose of building the data is the maintenance of the sewer system. Inconsistent simplification and supplementation of the sewer network data made by individual researchers may increase the uncertainty of flood simulations and influence the inundation analysis results. Therefore, it is necessary to develop a basic algorithm to convert the GIS-based sewage network data into input data that can be used for inundation simulations in consistent way. In this study, the format of GIS-based sewer network data for a watershed near the Sadang Station in Seoul and the Oncheon River Basin in Busan was investigated, and a missing data supplementing algorithm was developed. The missing data such as diameter, location, elevation of pipes and manholes were assumed following a consistent rule, which was developed referring to government documents, previous studies, and average data. The developed algorithm will contribute to minimizing the uncertainty of sewer network data in an urban inundation analysis by excluding the subjective judgment of individual researchers.

• 수도
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• s.67
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• pp.39-50
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• 1994

• 수도
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• v.22 no.2 s.72
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• pp.51-75
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• 1995

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.598-603
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• 2008

In petrochemical complex, Hydrogen Network optimization is surveying the extra Hydrogen and needed Hydrogen of each company and calculating the optimized distribution. This paper compares the case of using the existing pipeline and the case of not using the existing pipeline to show the effect quantitatively and clearly by modeling the both cases and using mathematical programming. As a result, using the existing pipeline can save the pipe cost over 20% and increase the whole network benefit by thirteen billion won.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.69-74
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• 1999

Upland Irrigation Network Analysis System(UINAS) used Object-Oriented Programming (OOP). The results of using OOP is definition of objects and class hierarchy for UINAS, Objects of UINAS are consist of the Pipe , Sprinkler, Valve , Pump, Tee , Bend and Contractions. The classj hierarchy have cooperative design for FEM in analysing the irrigation network. Therefore UINAS have a flexiblility in additioning the network components.

• 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.

• Journal of Korea Water Resources Association
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• v.52 no.8
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• pp.555-563
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• 2019

Reduced thickness of the water pipes due to corrosion makes it difficult to perform the original functions since corrosion in metallic water pipes can occur over time. In this study, reliability model that can estimate the probability of pipe breakage is developed regarding corrosion depth increment according to service year. Probability of pipe breakage was calculated by FORM(First Order Reliability Method) and unsteady analysis was performed to analyze the statistical properties of water pressure. And KCIP(Korea Cast Iron Pipe) equation was adopted for the reliability function. Furthermore, change of pipe thickness was estimated by Nahal and Khelif equation and Romanoff equation. Therefore, pipe thickness was calculated due to change of corrosion depth and probability of pipe breakage was calculated and compared with 10, 20, 30 service years. From the results, probability of pipe breakage for network A is gradually increased from 6.8% to 8.6% according to service year of 10, 20, 30 when Nahal and Khelif equation is applied. And probability of pipe breakage for network A is also gradually increased from 6.4% to 8.9% according to service year of 10, 20, 30 when Romanoff equation is applied.

• Structural Engineering and Mechanics
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• v.47 no.2
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• pp.167-183
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• 2013

Methods for estimating structural reliability using probability ideas are well established. When the residual ultimate strength of a buried pipeline is exceeded the limit, breakage becomes imminent and the overall reliability of the pipe distribution network is reduced. This paper is concerned with estimating structural failure of underground flexible pipes due to corrosion induced excessive deflection, buckling, wall thrust and bending stress subject to externally applied loading. With changes of pipe wall thickness due to corrosion, the moment of inertia and the cross-sectional area of pipe wall are directly changed with time. Consequently, the chance of survival or the reliability of the pipe material is decreased over time. One numerical example has been presented for a buried steel pipe to predict the probability of failure using Hasofer-Lind and Rackwitz-Fiessler algorithm and Monte Carlo simulation. Then the parametric study and sensitivity analysis have been conducted on the reliability of pipeline with different influencing factors, e.g. pipe thickness, diameter, backfill height etc.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.322-331
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• 2017

District heating was first introduced in Korea in 1985. As the service life of the underground thermal piping network has increased for more than 30 years, the maintenance of the underground thermal pipe has become an important issue. A variety of complex technologies are required for periodic inspection and operation management for the maintenance of the aged thermal piping network. Especially, it is required to develop a model that can be used for decision making in order to derive optimal maintenance and replacement point from the economic viewpoint in the field. In this study, the analysis was carried out based on the repair history and accident data at the operation of the thermal pipe network of five districts in the Korea District Heating Corporation. A failure probability model was developed by introducing statistical techniques of qualitative analysis and binomial logistic regression analysis. As a result of qualitative analysis of maintenance history and accident data, the most important cause of pipeline damage was construction erosion, corrosion of pipe and bad material accounted for about 82%. In the statistical model analysis, by setting the separation point of the classification to 0.25, the accuracy of the thermal pipe breakage and non-breakage classification improved to 73.5%. In order to establish the failure probability model, the fitness of the model was verified through the Hosmer and Lemeshow test, the independent test of the independent variables, and the Chi-Square test of the model. According to the results of analysis of the risk of thermal pipe network damage, the highest probability of failure was analyzed as the thermal pipeline constructed by the F construction company in the reducer pipe of less than 250mm, which is more than 10 years on the Seoul area motorway in winter. The results of this study can be used to prioritize maintenance, preventive inspection, and replacement of thermal piping systems. In addition, it will be possible to reduce the frequency of thermal pipeline damage and to use it more aggressively to manage thermal piping network by establishing and coping with accident prevention plan in advance such as inspection and maintenance.