• 한국농공학회논문집
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• 제47권5호
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• pp.3-13
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• 2005

The present study examined the 3 dimensional space distribution characteristics of sea water intrusion using data available from previous observations. For this study, we used 3D FEMWATER, which is a 3 dimensional finite element model. The target area was around Daechang-ri, Gimje-si, Jeollabuk-do. The area is relatively easy to formulate a conceptual model and has observation wells in operation for surveying sea water intrusion. Considering the uncertainty of numerical simulation, we analyzed sensitivity to hydraulic conductivity, which has a relatively higher effect. According to the result of the analysis, the variation of TDS concentration had an error range of $-1,336{\~}+107 mg/{\iota}$. Taking note that the survey data from observation wells were collected when the boundary between fresh water and sea water in the aquifer was in equilibrium, we set the range of time for numerical simulation and estimated the spatial distribution of TDS concentration as the range of sea water intrusion. According to the result of estimation, the spatial distribution of TDS concentration calculated when 1,440 days were simulated was taken as the range of sea water intrusion. Using the result of calculation, we can draw not only vertical views for a certain section but also horizontal views of different depth. These views will be greatly helpful in understanding the spatial distribution of the range of sea water intrusion. In addition, the result of this study can be used rationally in proposing an optimal quantity of water pumping through investigating the moving route of sea water intrusion over time in order to prevent excessive water pumping and to maintain an optimal number of water pumping wells per interval.

• 한국농공학회논문집
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• 제61권2호
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• pp.97-104
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• 2019

The purpose of this study was to establish the estimation method of irrigation water amount for sewage treated water reuse for agricultural purpose. To calculate the irrigation water amount, we adopted Penman-Monteith for potential evapotranspiration estimation and applied crop coefficient and irrigation efficiency factor. We developed the irrigation water amount calculation program using C language in Xcode environment. The target district for calculation is having 259 ha of agricultural land located near the Jinyeong Clear Water Circulation Center in Hanrim-myeon, Gimhae city. The meteorological data of the study area were obtained from Changwon weather station from 1986 to 2017. Calculated average and maximum of annual mean potential evapotranspiration were 2.72 mm/day and 6.22 mm/day, respectively. We used K-S (Kolmogorov-Smirnov) for goodness-of-fit test to find optimal probability distribution of annual mean and maximum evapotranspiration. As a result, the normal distribution was selected for the appropriate distribution. The annual mean and maximum potential evapotranspiration for 10-year return period by applying normal distribution were 2.88 mm/day and 6.76 mm/day, respectively. Assuming that the irrigation efficiency is 80%, the irrigation water requirement was calculated as $36.05m^3/day/ha$ and $84.45m^3/day/ha$, respectively, when annual mean and maximum potential evapotranspiration were applied. The actual irrigation water amount can be calculated by applying the crop coefficient and cropping days for the study area based on the developed irrigation water amount estimation program in this study.

• 펄프종이기술
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• 제38권1호통권113호
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• pp.62-69
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• 2006

This study was carried out to measure and analyze the storage condition, distribution route, and packaging method of four selected agricultural products(small tomato, cabbage, peach, and carrot) in the cold chain system. It was shown that dew-forming phenomenon by fruits and vegetables deteriorates the agricultural product quality and physical properties of corrugated fiberboard box during the cold chain system. The compressive strength deterioration in corrugated fiberboard boxes was much greater for single wall(SW) corrugated fiberboard containers than for double wall(DW) in low temperature-high humidity condition. To reduce the deterioration of box and dew-forming phenomenon, water-repellency treatment should be over $R_6$. However, water-resistant treatment of corrugated fiberboard containers would be effective under high relative humidity conditions more than 75% RH. It was suggested that functional corrugated fiberboard box packaging would be an optimum method to reduce the deterioration of agricultural products quality by. It was also achieved controlling the relative humidity and temperature during the storage and physical distribution process.

• 상하수도학회지
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• 제23권1호
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• pp.77-87
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• 2009

In existing systems, the best method inhibiting corrosion control in water distribution systems is to reduce water corrosiveness. Water corrosion can be decreased by controlling water quality through simple water treatment in treatment plants. On this research, we study the characteristics of tab water qualities in domestic areas, assessment of corrosive water quality and the method of water quality monitoring. This review presents the method of water quality monitoring which is the most applicable. Monitoring for corrosion control in waterworks system is the most proper method; It can prevent serious accidents economically and reduce civil appeals. Surely we should assess corrosive water quality in tab water, and introduce water treatment methods to control corrosive water quality before monitoring for corrosion. According to a lot of researches, it has been proved that simple water treatments can reduce the pipe corrosion. In this review we should indicate that we do not control of the corrosive water quality due to domestic conditions, we should monitor the water quality basically. Therefore, we recognize how the existing water quality can cause problems on pipeline corrosion, how to deal with it. Then it will be possible to apply water quality monitoring for corrosion control in water distribution system. Monitoring for corrosion control can be expressed by LI index, it is already known in literatures. This review presents more simple method than existing methods than existing ones we expect to apply these methods to SCADA in the future.

• 융복합기술연구소 논문집
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• 제4권2호
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• pp.61-65
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• 2014

Pressure distribution around rotating impeller blades in centrifugal pump has been main issue for design of efficient and high performance automotive water pump. In addition, pressure losses of inlet water pipes should be considered to reduce additional pressure drop and design high performance engine cooling system. In this paper, pressure distribution inside water pump and pressure drop between inlet and outlet of water pump are investigated numerically to design plastic water pump for clean diesel engine application. And the inlet geometry of water pump was considered to analysis the effect of inlet water pipe geometry on pressure distribution around impeller blades and outlet pressure. The prediction results are compared with experimental data to validate and determine optimal operation condition without water pump cavitation. Major design parameters such as blade angle, volute geometry, system pressure, and coolant flow rate are considered to confirm applying possibility of plastic blades to the clean diesel engine.

• 상하수도학회지
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• 제29권3호
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• pp.371-380
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• 2015

Particulate matters in a water distribution system are main causes of turbidity and discoloration of tap water. They could be removed by conventional or uni-directional flushing in a water distribution system. The behaviors and required flow velocity of particles are not well known for their flushing. A model water main and hydrant were made from transparent acrylic pipe of 30mm and 16mm in diameter, respectively. We analyzed the effect of flushing velocity, particle density, and particle diameter. We found that the existence of break-though velocities at which particles begin to be removed, and which are affected by their physical properties. The removal efficiencies seemed to be influenced by resuspension capabilities related to their upward movement from the bottom. Heavy particles like scale were hard to remove through upflow hydrant because the falling velocity, calculated using Stokes' law, was higher. Particle removal efficiencies of upward hydrant and downward drain showed minor differences. Additionally, the length between hydrant and control valve affected flushing efficiency because the particulate matters were trapped in this space by inertia and recirculating flow.

• Computers and Concrete
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• 제15권4호
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• pp.485-501
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• 2015

Cooling by the flow of water through an embedded cooling pipe has become a common and effective artificial thermal control measure for massive concrete structures. However, an extreme thermal gradient induces significant thermal stress, resulting in thermal cracking. Using a mesoscopic finite-element (FE) mesh, three-phase composites of concrete namely aggregate, mortar matrix and interfacial transition zone (ITZ) are modeled. An equivalent probabilistic model is presented for failure study of concrete by assuming that the material properties conform to the Weibull distribution law. Meanwhile, the correlation coefficient introduced by the statistical method is incorporated into the Weibull distribution formula. Subsequently, a series of numerical analyses are used for investigating the influence of the correlation coefficient on tensile strength and the failure process of concrete based on the equivalent probabilistic model. Finally, as an engineering application, damage and failure behavior of concrete cracks induced by a water-cooling pipe are analyzed in-depth by the presented model. Results show that the random distribution of concrete mechanical parameters and the temperature gradient near water-cooling pipe have a significant influence on the pattern and failure progress of temperature-induced micro-cracking in concrete.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.147-147
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• 2021

A partition of water distribution network (WDN) into district metered areas (DMAs) brings the efficiency and efficacy for water network operation and management (O&M), especially in monitoring pressure and leakage. Traditionally, the DMA configurations (i.e., number, shape, and size of DMAs) are permanent and cannot be changed occasionally. This leads to changes in water quality and reduced network redundancy lowering network resilience against abnormal conditions such as water demand variability and mechanical failures. This study proposes a framework to automatically divide a WDN into dynamic DMA configurations, in which the DMA layouts can self-adapt in response to abnormal scenarios. To that aim, a complex graph theory is adopted to sectorize a WDN into multiscale DMA layouts. Then, different failure-based scenarios are investigated on the existing DMA layouts. Here, an optimization-based model is proposed to convert existing DMA layouts into dynamic layouts by considering existing valves and possibly placing new valves. The objective is to minimize the alteration of flow paths (i.e., flow direction and velocity in the pipes) while preserving the hydraulic performance of the network. The proposed method is tested on a real complex WDN for demonstration and validation of the approach.

• 상하수도학회지
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• 제26권6호
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• pp.861-869
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• 2012

The chlorine's residual concentration prevents the regrowth of microorganism in water transport along the pipeline system. Precise prediction of chlorine concentration is important in determining disinfectant injection for the water distribution system. In this study, a pilot scale water distribution system was designed and fabricated to measure the temporal variation of chlorine concentration for three flow conditions (V = 0.88, 1.33, 1.95 m/s). Various kinetic models were applied to identify the relationship between hydraulic condition and chlorine decay. Genetic Algorithm (GA) was integrated into five kinetic models and time series of chlorine were used to calibrate parameters. Model fitness was compared by Root Mean Square Error (RMSE) between measurement and prediction. Limited first order model and Parallel first order showed good fitness for prediction of chlorine concentration.

• 상하수도학회지
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• 제24권5호
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• pp.573-580
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• 2010

Average pressure in a pipe network is one of critical factors to estimate the flow distribution and to calculate UARL (Unavoidable Annual Real Losses) value in ILI (Infrastructure Leakage Index). While its collection period and measuring location are essential to obtain average pressure, their standard method have not been established so far. In this study, proper method including its procedure for data collection period and measuring point for average pressure were suggested using non-exceedance probability concept in the water distribution network.