• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.693-696
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• 2005

KIGAM (Korea Institute of Geoscience and Mineral Resources) launched a new project to develop the low-temperature geothermal water in the area showing high geothermal anomaly, north of Pohang city, for large-scale space heating. Surface geologic and geophysical surveys including Landsat 1M image analysis, gravity, magnetic, Magnetotelluric (MT) and controlled-source audio-frequency MT (CSAMT), and self-potential (SP) methods have been conducted and the possible fracture zone was found that would serve as deeply connected geothermal water conduit. In 2004, two test wells of 1.1km and 1.5km depths have been drilled and various kinds of borehole survey including geophysical logging, pumping test, SP monitoring, core logging and sample analysis have followed. Temperature of geothermal water at the bottom of 1.5km borehole reached over $70^{\circ}C$ and the pumping test showed that the reservoir contained huge amount of geothermal water. Drilling for the production well of 2 km depth is on going. After test utilization and the feasibility study, geothermal water developed from the production well is going to be provided to nearby apartments.

• The KSFM Journal of Fluid Machinery
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• v.7 no.1 s.22
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• pp.51-57
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• 2004

The waterhammer has recently become more important because the pumping stations were big and the systems conveying the fluid through the large and long transmission pipelines were complex. When the pumps are started or stopped for the operation or tripped due to the power failure, the hydraulic transients occur as a result of the sudden change in velocity As the pressure waves are propagating between the pumping station and the distributing reservoir, the pressure inside the pipe drops to the liquid vapor pressure with the pipeline profile, at which time a vapor cavity forms, and finally the column separation occurs. If the pressure in the pipe is less than the atmospheric pressure, the pipe can be collapsed and destroyed after the water columns separated by the vapor cavity rejoin. During the reverse flow, the pressure is so abnormally increased at the pumping station that the accident of flooding may happen due to the failure of system. In this paper, the field tests on the waterhammer by the startup, stoppage, and power failure of a centrifugal pump were carried out for Yongma transmission pumping station in Seoul. The experimental results were compared with that of the numerical calculations, in which results the procedure of controlled pump normal shut-down and the two-step closing mode of controlling the ball valve for pump emergency stop are proposed to reduce the pressure surge.

• Journal of Appropriate Technology
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• v.5 no.1
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• pp.8-17
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• 2019

Solar pumps, for water lift systems, is becoming popular in rural areas for supplying drinking water in dry seasons when its need is elevated. The development in technology has also made solar pumps readily available and cheap which has increased its demands. So, for scattered settlements having a limited budget for operation and maintenance costs, solar pump is preferred over grid connected electrical pumping systems. This primary objective of the study was to design a solar photovoltaic pumping drinking water supply system for a small health post which is about 45 km east from Kathmandu, the capital city of Nepal. The study also compared and verified the final design with the system's existing design prepared by a development agency. The water source for this study was a confined aquifer 115m below the surface. The water demand was calculated to be 11m³ per day. A 1500 kPa submersible pump attached to a motor was selected and installed. Along with that twelve solar panels, reservoir, transmission main and distribution main was designed. The outcomes conclude solar photovoltaic pumping water supply systems to be cost-effective with an estimated cost of only USD 0.84 million per MLD. Solar pumps require low maintenance and operation costs and its repairs can quickly be done by the local people. The study also shows that solar technology produces no sound, needs no fuel making it environmentally friendly.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.3
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• pp.169-174
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• 2018

A total of 594 reservoirs (17%), which are managed by KRC, equipped with earthquake-resistant facilities whereas remaining ones did not. In addition, reservoirs were placed without the effect of geological structures (i.e., fault and lineament). Therefore, development on technique for alleviating the potential hazards by natural disasters along faults and lineaments has required. In addition, an effective reinforcement guideline related to the geological vulnerabilities around reservoirs has required. The final goal of this study is to suggest the effective maintenance for the safety of earth fill dams. A radius 2 km, based on the center of the reservoir in the study area was set as the range of vulnerability impacts of each reservoir. Seismic design, precise safety diagnosis, seismic influence and geological structure were analyzed for the influence range of each reservoir. To classify the vulnerability of geological disasters according to the fault distribution around the reservoir, evaluation index of seismic performance, precise safety diagnosis, seismic influence and geological structure were also developed for each reservoir, which were a component of the vulnerability assessment of geological disasters. As a result, the reservoir with the highest vulnerability to geological disasters in the pilot district was analyzed as Kidong reservoir with an evaluation index of 0.364. Within the radius of 100km from the epicenter of the Pohang earthquake, the number of agricultural infrastructure facilities subject to urgent inspections were 1,180 including reservoirs, pumping stations and intakes. Four reservoirs were directly damaged by earthquake among 724 agricultural reservoirs. As a result of the precise inspection and electrical resistivity survey of the reservoir after the earthquake, it was reported that cracks on the crest of reservoirs were not a cause of concern. However, we are constantly monitoring the safety of agricultural facilities by Pohang aftershocks.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.5
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• pp.115-124
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• 2018

Resilience has been widely used in various fields including design and operation of infrastructures. The resilient infrastructures not only reduce the damage scale of various disasters but also reduce the time and cost required for restoration. However, resilience rarely applied to promote efficient management of agricultural infrastructures. Recently, drought is an aggravating disaster by climate change and need countermeasures. Therefore, we tried to demonstrate evaluating measures in case of drought under consideration of resilience. This study applied the robustness-cost index (RCI) to evaluate alternative solution of the supply problem of a large agricultural reservoir under drought conditions. Four structural alternatives were selected to estimate the robustness index (RI) and the cost index (CI) to obtain the RCI values. Structural alternatives are classified into temporary measures and permanent measures. Temporary measures include the development of a tube wells and the installation of the portable pump, while the permanent measures include the installation of a pumping stations and the pumping water to the reservoir (Yeongsan River-Naju reservoir). RCI values were higher in permanent measures than those of temporary measures. Initial storage of the reservoir also affected RCI values of the drought measures. Permanent measures installation and management of early stage of the reservoir storage shortage was identified as the most resilient system.

• Journal of Korea Water Resources Association
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• v.45 no.12
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• pp.1259-1273
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• 2012

In this study, a watershed-based surface water and groundwater integrated model, SWAT-MODFLOW was used to quantify the stream flow depletion due to groundwater pumping for the Sinduncheon watershed. Complex water use conditions such as water taken from a stream, sewage disposal release, irrigation from agricultural reservoir, groundwater pumping were considered for simulations. In particular, the model was revised to reflect the effects of reservoir operation and return flow from the used groundwater on streamflow variation. The simulated results showed that the groundwater pumping at current status has induced the decrease of more than 10% in annual average streamflow and 40% in drought flow at the outlet of the Sinduncheon watershed, The simulated results also revealed that the vast water withdrawals at green house areas during winter season have dramatically changed streamflow from April to June. The streamflow depletion was mainly attributed to pumping wells located within the distance of 300 m from the stream for Sinduncheon watershed.

• Geomechanics and Engineering
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• v.9 no.5
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• pp.645-667
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• 2015

Single treatment and staged treatments in vertical wells are widely applied in sandstone and mudstone thin interbedded (SMTI) reservoir to stimulate the reservoir. The keys and difficulties of stimulating this category of formations are to avoid hydraulic fracture propagating through the interface between shale and sand as well as control the fracture height. In this paper, the cohesive zone method was utilized to build the 3-dimensional fracture dynamic propagation model in shale and sand interbedded formation based on the cohesive damage element. Staged treatments and single treatment were simulated by single fracture propagation model and double fractures propagation model respectively. Study on the changes of fracture vicinity stress field during propagation is to compare and analyze the parameters which influence the interfacial induced stresses between two different fracturing methods. As a result, we can prejudge how difficult it is that the fracture propagates along its height direction. The induced stress increases as the pumping rate increasing and it changes as a parabolic function of the fluid viscosity. The optimized pump rate is $4.8m^3/min$ and fluid viscosity is $0.1Pa{\cdot}s$ to avoid the over extending of hydraulic fracture in height direction. The simulation outcomes were applied in the field to optimize the treatment parameters and the staged treatments was suggested to get a better production than single treatment.

• Geophysics and Geophysical Exploration
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• v.7 no.3
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• pp.164-173
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• 2004

To delineate geothermal water movement at the Pohang geothermal development site, Self-Potential (SP) survey and monitoring were carried out during pumping tests. Before drilling, background SP data have been gathered to figure out overall potential distribution of the site. The pumping test was performed in two separate periods: 24 hours in December 2003 and 72 hours in March 2004. SP monitoring started several days before the pumping tests with a 128-channel automatic recording system. The background SP survey showed a clear positive anomaly at the northern part of the boreholes, which may be interpreted as an up-flow Bone of the deep geothermal water due to electrokinetic potential generated by hydrothermal circulation. The first and second SP monitoring during the pumping tests performed to figure out the fluid flow in the geothermal reservoir but it was not easy to see clear variations of SP due to pumping and pumping stop. Since the area is covered by some 360 m-thick tertiary sediments with very low electrical resistivity (less than 10 ohm-m), the electrokinetic potential due to deep groundwater flow resulted in being seriously attenuated on the surface. However, when we compared the variation of SP with that of groundwater level and temperature of pumping water, we could identify some areas responsible to the pumping. Dominant SP changes are observed in the south-west part of the boreholes during both the preliminary and long-term pumping periods, where 3-D magnetotelluric survey showed low-resistivity anomaly at the depth of $600m\~1,000m$. Overall analysis suggests that there exist hydraulic connection through the southwestern part to the pumping well.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.3
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• pp.107-114
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• 1992

With the increasing of impervious area and shortening of travel time, the risk of flooding in urban area becomes a serious problem in Seoul metropolitan area, and its alternatives are needed. In this study, one of urban flood alternatives, a fuzzy control technique is applied in pumping station to test its drainage capacity of inland inflow, and compared with existing pumping criteria (controled by water level). Three design rainfalls(10, 30, and 50 year) are applied to ILLUDAS model to calculate inflow in detention reservoir. To check the efficiency of fuzzy control, two fuzzy rules are used in the operation of pumping station. In these results, fuzzy control rules, based on the experiences of experts, show applicability in practice and effectiveness in inland flooding prevention.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1899-1903
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• 1991

This paper presents a water level control method using Z-80 microcomputer. The process considered in this paper is one tank system which is described by an unknown nonlinear differential equation. The water level is measured by the end of bar installed at a float passing through 8 pair of photointerrupters located at equal distance. Therefore, the input data to 8255 which is interface between Z-80 and photointerrupters is discrete value, namely, value under 1. values from 1 to 8, and value upper 8. The water is pumped into the tank from a reservoir by switching on a relay connected to a moter and pump driving system. The pumping is stopped by switching off the relay. Experimental studies for two types of controllers are performed in order to investigate the control performance of water level of the water pumping system.