• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.6
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• pp.41-53
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• 2019

Recently, the damage caused by climate change has been distinguished in the world. The Korean Peninsula is also suffering from drought, so it is necessary to study the vulnerability assessment to identify and predict the state of the irrigation facility, which is a irrigation facility. As the damage caused by drought is occurring in the Korean peninsula, it is necessary to study the vulnerability assessment to know the condition of the irrigation facility, and to predict it. The target areas were Yeongdong-gun, Cheonan-si, Mungyeong-si, Geochang-gun, Muju-gun, and Yeonggwang-gun. The survey items were selected as positive impacts survey items, including precipitation, groundwater level, and pumping capacity per groundwater well. The negative impacts were selected as the cultivation acreage, Number of days without rain, and the ratio of private underground wells. The survey method was investigated by various methods such as "weather data portal", "groundwater level status information", "agricultural drought management system", "groundwater survey yearbook". The results of vulnerability assessment were expressed by the score by conducting survey and standardization. As a result, Yeonggwang-gun showed normal vulnerability, and other areas showed "vulnerable" or "very vulnerable".

• Journal of Korea Water Resources Association
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• v.51 no.spc
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• pp.1149-1159
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• 2018

This study aims to predict the future flood damage cost of 113 middle range watersheds using 26 GCM outputs, hourly maximum rainfall, 10-min maximum rainfall, number of days of 80 mm/day, daily rainfall maximum, annual rainfall amount, DEM, urbanization ratio, population density, asset density, road improvement ratio, river improvement ratio, drainage system improvement ratio, pumping capacity, detention basin capacity and previous flood damage costs. A constrained multiple linear regression model was used to construct the relationships between the flood damage cost and other variables. Future flood damage costs were estimated for different RCP scenarios such as 4.5 and 8.5. Results demonstrated that rainfall related factors such as annual rainfall amount, rainfall extremes etc. widely increase. It causes nationwide future flood damage cost increase. Especially the flood damage cost for Eastern part watersheds of Kangwondo and Namgang dam area may mainly increase.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.4
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• pp.429-436
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• 2005

A coagulation/ultrafiltration membrane hybrid system was operated to treat river water with capacity of $0.06m^3/d$. The impact on membrane fouling by flux and linear velocity was investigated. It is known that pressure increase is proportional to flux increase. However, pressure increase was much faster than theoretical value in the pilot plant test. So it was suggested that flux was on important factor in ultrafiltration of continuous operation. Membrane fouling was decreased when linear velocity was increased. This phenomenon was found more obviously without coagulation. With the combination of coagulation and sedimentation, membrane fouling was not reduced conspicuously. Big particles formed during coagulation and sedimentation were destroyed by feed and circulation pumping, which resulted in little effect on membrane fouling reduction. The degree of destruction was similar at various linear velocities. In this study, the hollow fiber membrane was used and the system was operated in pressure type module. In case of the system used in this study, membrane fouling has been affected lightly by linear velocity variation when coagulation pretreatment was applied.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.4
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• pp.455-460
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• 2014

South Korea's power consumption is increasing every year. For stable electric power supply, more generation facilities are needed. But it is not easy to build nuclear power generation facilities, so provision of renewable energy is thought of as the solution. For the system's stable management, practical use of energy storing system is needed. Currently, pumping up electric power station is considered most useful. In this study, we have calculated the least amount of energy storing device by considering the renewable energy, HVDC, and change in power for the appliance of ESS in Jeju system, according to The 6th Basic Plan for Long-term Electricity Supply and Demand. Also we have calculated the amount of the battery and about the load equalizing effect to use battery as power storing device. Finally, we have calculated the reduction of electricity generation and the reduction of $CO_2$ emission with this study.

• Journal of Industrial Technology
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• v.22 no.A
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• pp.127-135
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• 2002

In this study, the preliminary risk assessment for the underground storage tanks(UST) in Chunchon city was implemented using the geographical information system(GIS). The estimation variables, such as the installation year, storage capacity, the distances from streams, and from groundwater pumping wells, were selected to estimate the relative risk levels. The weighting factors were given to all the estimation variables. Cumulative scores were induced by the combination of all the scores of the corresponding variables using the buffering technique and the overlay analysis in ArcView. Using the these process, the relative risk level of each UST was estimated. Some sites in this study are simplified and reduced because the number of useable data are limited or too enormous. Thus the selection of the comprehensive estimation variables and the proper weighting values are required for the future study. The methodology in this study could be served not only for the preliminary risk assessment of UST but also for the selection of the proper location of new and old UST. And, it can be used for the effective management system of UST.

• Journal of computational fluids engineering
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• v.17 no.4
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• pp.1-8
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• 2012

During a reactor normal operation, two parallel 50% capacity cooling pumps circulate primary coolant to remove the fission reaction heat of the reactor through heat exchangers cold by a cooling tower. When one pump is failure, the other pump shall continuously circulate the coolant to remove the residual heat generated by the fuels loaded in the reactor after reactor shutdown. It is necessary to estimate how much flow rate will be supplied to remove the residual heat. We carried out a flow network analysis for the parallel primary pumps based on the piping network of the primary cooling system in HANARO. As result, it is estimated that the flow rate of one pump increased about 1.33 times the rated flow of one pump and was maintained within the limit of the cavitation critical flow.

• Journal of Soil and Groundwater Environment
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• v.7 no.2
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• pp.23-33
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• 2002

There are two case history. One is the case of 3 wells-group well system-drilled and artificially hydrofractured for dewatering to help to excavate and treat deep building foundation. The recoveries of groundwater of 3 wells are increased 29%, 42% and 110% respectively through hydrofracturing. Simultaneous pumping test reveals that 3 wells are geohydrologically interconnected considering lowered specific capacity comprising influence of additional drawdown effect by other 2 wells compared to single well test. Response time effect during single well test shows that dorminant lineaments are more expandable to other geological structures. The other one is the case of 28% increasing of groundwater productivity for domestic use by hydrofracturing.

• Geomechanics and Engineering
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• v.19 no.5
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• pp.447-462
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• 2019

The vacuum preloading method has been used in many countries for ground improvement and land reclamation works. A sand cushion is required as a horizontal drainage channel for conventional vacuum preloading. In terms of the dredged-fill foundation soil, the treatment effect of the conventional vacuum preloading method is poor, particularly in Tianjin, China, where a shortage of sand exists. To solve this problem, straight-line vacuum preloading without sand is widely adopted in engineering practice to improve the foundation soil. Based on the engineering properties of dredged fill in Lingang City, Tianjin, this paper presents field instrumentation in five sections and analyzes the effect of a prefabricated vertical drain (PVD) layout and a vacuum pumping method on the soft soil ground treatment. Through the arrangement of pore water pressure gauges, settlement marks and vane shear tests, the settlement, pore water pressure and subsoil bearing capacity are analyzed to evaluate the effect of the ground treatment. This study demonstrates that straight-line vacuum preloading without sand can be suitable for areas with a high water content. Furthermore, the consolidation settlement and consolidation degree system is developed based on the grey model to predict the consolidation settlement and consolidation degree under vacuum preloading; the validity of the system is also verified.

• Journal of Korea Water Resources Association
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• v.31 no.2
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• pp.133-144
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• 1998

Recent development booms in urban watersheds have increased impermeable areas and brought about an increase of peak flood. Eventually, some people living in the lower area of an urban watershed, very often and seriously, have suffered form inundation. In this study, for minimization of inundation in urban watersheds, the operational criteria for pump stations are suggested. At first, ILLUDAS has been selected as a runoff model which can explain the past precipitations. Secondly the operational criteria for pump stations could be suggested by working out an operational criteria for pump stations could be suggested by working out an operation program from the relationship between pumping capacity and accumulative hydrographs, and from the Intensity-Duration-Frequency relationship.

• Korean Journal of Hydrosciences
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• v.8
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• pp.31-40
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• 1997

Flow carrying capacity of water distribution systems is getting reduced by deterioration of pipes in the systems. The objective of this paper is to present a managerial decision-making model for the rehabilitation of water distribution systems with a mininum cost. The decisions made by the model also satisfy the requirements for discharge and pressure at demanding nodes in the systems. Replacement cost, pipe break repair cost, and pumping cost are considered in the economic evaluation of the decision along with the break rate and the interest rate to determine the optimal replacement time for each pipe. Then, the hydraulic integrity of the water distribution system is checked for the decision by a pipe network simulator, KYPIPE, if discharge and pressure requirements are satisfied. In case the system does not satisfy the hydraulic requirements, the decision made for the optimal replacement time is revised until the requirments are satisfied. The model is well applied to an existing water distribution system, the Seoul Metropolitan Water Supply System (1st Phase). The results show that the decisions for the replacement time determined by the economic analysis are accepted as optimal and hydraulic integrity of the system is in good condition.