• Journal of Korean Society of Water and Wastewater
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• v.28 no.6
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• pp.699-711
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• 2014

This study was carried out to analyze water suspension in the water supply system through fault tree analysis. And quantitative factors was evaluated to minimize water suspension. Consequently the aim of this study is to build optimal planning by analyzing scenarios for water suspension. Accordingly the fault tree model makes it possible to estimate risks for water suspension, current risks is $92.23m^3/day$. The result of scenario analysis by pipe replacement, risks for water suspension was reduced $7.02m^3/day$ when replacing WD4 pipe. As a result of scenario analysis by water district connections, the amount of risk reduction is maximized when it is connecting to network pipe of D Zone. Therefore, connecting to network pipe for D Zone would be optimal to reduce risk for water suspension.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.5
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• pp.428-432
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• 2012

In the waste collection system, living waste is collected through the piping network. There are many confluent pipes in a piping network. These confluent pipes were often clogged up with waste. The optimal configuration of the confluent pipes has been defined by the design guide. However, nobody know how this design guide were determined. Therefore, in this paper, we found the design data for the confluent pipe configuration in order to avoid the waste clogging in a piping network. The distance between connected point on the confluent pipes should be longer than the previous design guide.

• Journal of Korean Institute of Industrial Engineers
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• v.10 no.2
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• pp.17-27
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• 1984

This paper is concerned with a branched pipe network system which transports some fluids or gas from multiple sources to multiple demand nodes. A nonlinear programming model is proposed for determining junction locations simultaneously with selection of pipe sizes and pump capacities such that the capital and operating costs of the system are minimized over a given planning horizon. To solve the model, a hierarchical decomposition method is developed with the junction location being the primary variable. With some values fixed for the primary, the other decision variables are found by linear programming. Then, using the postoptimality analysis of LP, junction locations are adjusted. We repeat this process until an optimum is approached. A simple example of designing a water distribution network is solved to illustrate the optimization procedure developed.

• Journal of Power System Engineering
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• v.2 no.1
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• pp.45-51
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• 1998

An analyzing method for pressure fluctuations in oil hydraulic pipe network was developed in this study. The object pipe network has multi-branch configuration, and the pipelines of it are composed of metal tubes and flexible hoses. Transfer matrix method, in other words impedance method, was used for the analysis. Values of physical parameters describing the characteristics of flexible hose were measured by experiments and reflected to the analysing procedure. The reliability and usefulness of the analyzing method were confirmed by investigating computed results and experimental results got in this study.

• Journal of the Korean Association of Geographic Information Studies
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• v.4 no.4
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• pp.21-28
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• 2001

In this study, GNLP(GIS linked non-linear network analysis program) for pipeline system analysis has been developed. This GNLP gets the input data for pipeline analysis from existing GIS(geographic information system) data automatically, and has GUI(graphic user interface) for user. Non-Linear Method was used for hydraulic analysis of pipe network based on Hazen-Williams equation, and Microsoft Access of relational database management system(RDBMS) was used for the framework of database applied program. GNLP system environment program was improved so that a pipe network designer can input information data for hydraulic analysis of pipeline system more easily than that of existing models. Furthermore this model generate output such as pressure and water quantities in the form of a table and a chart, and also produces output data in Excel file. This model is also able to display data effectively for analysed data confirmation and query function which is the core of GIS program.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1448-1453
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• 2004

The major parameters governing the fluid dynamical and thermo-dynamical behavior in the large pipeline network system are friction loss and the pipeline length. But in local pipeline networks and relatively short distance pipeline system, secondary loss and the considerations of the moving states of the fluid machine are also important. One of the major element in local pressure control system is pressure regulator. It causes the variations of the physical properties in that pipeline system. Especially, as there is not enough information to obtain reliable physical property values such as density, temperature etc. at the downstream of the pressure regulator, It is hard to calculate accurate solution in the pipeline network analysis. In this study, some numerical approaches to investigate the critical-flow-characteristics of the pressure regulator have been done and the detail examinations and considerations of the pressure regulator as a pipeline network elements according to the variations of the inlet-outlet pressure ratio have been carried. Finally the flow-flied distributions, relations and critical-flow-characteristics have been studied. in detail and the 1D analytic method to analyze critical pipe flow have been investigated

• Journal of Korean Society of Water and Wastewater
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• v.27 no.4
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• pp.479-487
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• 2013

This study was to investigate characteristics for the pressure wave propagation and the maximum pressure near a rapid closure valve which was installed the end of multi piping network. The multi piping network consists of one inlet and three outlet with straight pipes. The diameter of the pipes including the valve was 100 mm, 80 mm, 80 mm respectively. The valve was rapidly closed with the instantaneous time which was 0.023s in the level for the water hammer. For the simulation, the influence of the pipe thickness and deformation due to pressure-wave-propagation was not considered. CFD was conducted under the following condition : the initial pressure was 1bar in the inlet and the mass flow rate was 7.83 kg/s in the outlet(the velocity in the pipe with 100 mm diameter was 1 m/s). As the valve have conditions that were status with and without fluid flow in the pipe after valve closing, the maximum pressure change and the frequency analysis were examined. As the results, the case that was status with fluid flow appeared the higher maximum pressure than another's, the maximum frequency band was about 10 ~ 11 Hz.

• Journal of the Korean housing association
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• v.19 no.5
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• pp.111-120
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• 2008

The aim of this study is to present the design methods about manifold location being installed and size and to draw out the proper piping size as comparing the fluctuation of discharge with manifold size and residence size through the piping network analysis, when using the same faucet in accordance. The findings are summarized as follows, 1) an appropriate header main body pipe diameter was deemed to be $32{\sim}50\;mm$. 2) the research presented design measures for the application of appropriate water supply inlet pipe diameters according to residential buildings with various sizes. 3) the header direct branch piping method is ideal for small and medium-sized residential complexes, and the header branching and semi header methods are deemed to be more favorable for large residential complexes. 4) this study offered design measures for appropriate header system main body pipe diameters, water supply inlet pipe diameters, header system piping methods, application methods for functional auxiliary equipment units, and header system installation spaces and location.

• Proceedings of the Korea Water Resources Association Conference
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• 2002.05b
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• pp.829-836
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• 2002

The paper presents a multi-objective genetic algorithm approach to the design of a water distribution network. The objectives considered are minimization of network cost and maximization of a reliability measure. In this study, a new reliability measure, called network resilience, is introduced. This measure mimics a designer's desire of providing excess power at nodes and designing reliable loops with practicable pipe diameters. The proposed method produces a set of Pareto-optimal solutions in the search space of cost and network resilience. Genetic algorithms are observed to be poor in handling constraints. To handle constraints in a better way, a constraint handling technique that does not require a penalty coefficient and applicable to water distribution systems is presented. The present model is applied to two example problems, which were widely reported. Pipe failure analysis carried out on some of the solutions obtained revealed that the network resilience based approach gave better results in terms of network reliability.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.3
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• pp.295-303
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• 2009

In the present study, a reliability analysis calculating the probability of system failure has been performed using cut set and results of numerical analysis for unsteady flow in pipe. Especially, the probability of system failure has been evaluated regarding the effect of valve closure which is a really important activity in operation of piping system. In spite of small amount of demand, it was found that fast valve closure can generate high probability of system failure. Furthermore, it was confirmed that surge tank can reduce the unsteady effects and probability of system failure in water distribution system. From the results, it was found that the unsteady flow has a significant effect on the probability of system failure Furthermore, it was able to find which pipe or cut set has high probability of system failure. So it could be used to determine which pipe or cut set has a priority of repair and replacement. Therefore, reliability analysis regarding unsteady flow has to be performed for the planning, designing, maintenance, and operation of piping system.