• 한국지하수토양환경학회지:지하수토양환경
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• 제21권1호
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• pp.61-71
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• 2016

Visual MODFLOW was used for quantifying stream-aquifer interactions caused by seasonal groundwater pumping. A hypothetical conceptual model was assumed to represent a stream-aquifer system commonly found in Korea. The model considered a two-layered aquifer with the upper alluvium and the lower bedrock and a stream showing seasonal water level fluctuations. Our results show that seasonal variation of the stream depletion rate (SDR) as well as the groundwater depletion depends on the stream depletion factor (SDF), which is determined by aquifer parameters and the distance from the pumping well to the stream. For pumping wells with large SDF, groundwater was considerably depleted for a long time of years and the streamflow decreased throughout the whole year. The impacts of return flow were also examined by recalculating SDR with an assumed ratio of immediate irrigation return flow to the stream. Return flow over 50% of pumping rate could increase the streamflow during the period of seasonal pumping. The model also showed that SDR was affected by both the conductance between the aquifer and the stream bed and screen depths of the pumping well. Our results can be used for preliminary assessment of water budget analysis aimed to plan an integrated management of water resources in riparian areas threatened by heavy pumping.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.697-700
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• 2005

Aquifer Thermal Energy Storage (ATES) system can be very cost-effective and renewable energy sources, depending on site-specific parameters and load characteristics. In order to develop an ATES system which has certain hydrogeological characteristics, understanding of the thermo hydraulic processes of an aquifer is necessary for a proper design of an aquifer heat storage system under given conditions. The thermo hydraulic transfer for heat storage is simulated using FEFLOW according to two sets of pumping and waste water reinjection scenarios of heat pump operation in a two layered confined aquifer. In the first set of model, the movement of the thermal front and groundwater level are simulated by changing the locations of injection and pumping well in seasonal cycle. However, in the second set of model the simulation is performed in the state of fixing the locations of pumping and injection well. After 365 days simulation period, the temperature distribution is dominated by injected water temperature and the distance from injection well. The small temperature change is appears on the surface compared to other slices of depth because the first layer has very low porosity and the transfer of thermal energy are sensitive at the porosity of each layer. The groundwater levels and temperature changes in injection and pumping wells are monitored to validate the effectiveness of the used heat pump operation method and the thermal interference between wells is analyzed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2064-2069
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• 2008

The Resonance Control Cooling System (RCCS) prototype installed in KAERI site has been designed to control the resonant frequency of the normal conducting drift tube linac (DTL) for the Proton Engineering Frontier Project (PEFP). The RCCS water pumping skid is composed of two channels as a by-passing the cooling water and a plate heat exchanger. The required temperature can be achieved by mixing both channels in order to control its the resonant frequency at 350 MHz. The temperature controlled water pumping skid operates in combination with the Low Level Radio Frequency (LLRF) system. We have discussed the design, modeling with each components, control scheme, fabrication and test results of the water pumping skid for resonant frequency control of the DTL cavity. In conclusion, the fabricated RCCS prototype through the optimization of modeling has corresponded with the design requirement and concept.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권9호
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• pp.484-489
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• 1999

This paper deals with the design and fabrication of a heater-trigger type high-Tc superconducting power supply system, and characteristics have been analyzed through experiments. The high-Tc superconducting power supply consists of two heater trigger and electric magnet, and YBCO superconducting bulk. In this experiment, 0.6T class magnet and dc 2.3A heater current are used, and the current-pumping characteristics have been analyzed with computer aided sequence control system. Hall sensors are installed on the YBCO bulk and in the center of iron core in order to analyze the effect of the flux-pumping on the system with when magnet flux changes its value. In this experiment, maximum pumping-current has been achieved to about 6.6 amps.

• 적정기술학회지
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• 제5권1호
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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.

• 한국수자원학회논문집
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• 제30권2호
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• pp.107-118
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• 1997

한국수자원공사가 수행한 중국 산서성 태원시 용수공급원인 분하강 상류 저수지 시스템은 매우 복잡하다. 이곳 저수지 시스템은 여러개의 저수지가 직렬로 연결될 계획이며, 운영에서도 여러 가지 목적이나 평가항목을 고려하는 다목적, 다기준 시스템이 될 것이다. 이 시스템에서 주요 저수지 운영목적은 용수부족과 저수지 퇴사량 최소화이나 황하도수사업이라는 대규모 펌핑 시스템과 연계 운영이 필요하다. 황하도수계획에서의 용수개발비는 저수지를 통한 개발비 보다 비싼 편이며, 2020년경의 필요 도수량은 자체 유역으로부터 지표수 공급량의 두배에 이를 것으로 전망된다. 본 연구에서는 분하 상류 저수지 시스템과 황하도수 시스템의 연계 운영문제를 해결하기 위하여 펌핑-저수지 시스템 최적화 모형을 개발하였다. 연구내용은 황하도수계획과 저수지 시스템의 연계 가능성을 입증하고 황하도수계획을 하나의 저수지화하여 실제 저수지 시스템과 연계하는 방법을 제시하고 있다. 또한 개발된 모형을 이용하여 여러 가지 기존의 저수지 운영목적을 만족시키면서 황하도수량 최소화에 대한 실제 적용 예를 제시하고 있다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.916-919
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• 2004

The monopole theory has long been used to model air-pumped effect from the elastic cavities in car tire. This approach models the change of an air as a piston moving backward and forward on a spring and equates local air movements exactly with the volume changes of the system. Thus, the monopole theory has a restricted domain of applicability due to the usual assumption of a small amplitude acoustic wave equation and acoustic monopole theory. This paper describes an approach to predict the air-pumping noise of a car ave with CFD/Kirchhoff integral method. The type groove is simply modeled as piston-cavity-sliding door geometry and with the aid of CFD technique flow properties in the groove of rolling car tyre are acquired. And these unsteady flow data are used as a air-pumping source in the next Cm calculation of full tyre-road geometry. Acoustic far field is predicted from Kirchhoff integral method by using unsteady flow data in space and time, which is provided by the CFD calculation of full tyre-road domain. This approach can cover the non-linearity of acoustic monopole theory with the aid of using Non-linear governing equation in CFD calculation. The method proposed in this paper is applied to the prediction of air-pumping noise of modeled car tyre and the predicted results are qualitatively compared with the experimental data.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.39-39
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• 1999

The KSTAR (Korea Superconducting Tokamak Advanced Research) tokamak is a nuclear fusion experimental device for a long pulse/steady-state plasma operation, adopting fully superconducting magnets. In accordance with completion of the basic design of the torus vacuum vessel and the enclosing cryostat, the vacuum pumping and gas fueling basic design has been developed to fulfil the physics requirements. The ultra-high vacuum pumping and sophisticated gas fueling system of the machine is essential to achieve such roles for optimized plasma performance and operation. Recently the vacuum exhaust system using dedicated pumping ports for the vacuum vessel and cryostat has been modified to meet more reliable and successful performance of the KSTAR[Fig. 1].In order to achieve the required base pressure of 5 x 10-9 torr, the total impurity load to the vessel internal is limited to ~5 x 10-5 torr-1/x, while the cryostat base pressure is kept as ~5 x 105 torr to mitigate the thermal load applied to the superconducting magnets. Each KSTAR fueling system will be separately capable of fueling gas at a rate of 50 torr-1/x, consistent with the given pumping throughput. In order to initiate a plasma discharge in KSTAR, the vacuum vessel is filled to a gas pressure of few 10-6 to few 10-4 torr, and additional gas injection is required to maintain and increase the plasma density during the course of the discharge period.

• 한국초전도ㆍ저온공학회논문지
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• 제6권1호
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• pp.43-48
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• 2004

This paper deals with design and fabrication of heater-triggered switching system for the high-Tc superconducting (HTS) power supply with series-connected double-pancake load. Amongst all components, heater triggering is the most important element for the performance of HTS power supply. To fabricate the optimal heater-triggered system, its characteristics have been analysed through the simulation and expriment. The thermal analysis of switching parts of the Bi-2223 solenoid according to the heater input was carried out. Based upon the analysis, 8A electromagnet current and 1.5A DC Heater current were optimally derived, and 8s and 20s for the pumping period were selected in this experiment. In the experiment. the maximum pumping current reached about 24A with Bi-2223 pancake load of 6mH.

• 상하수도학회지
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• 제26권6호
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• pp.915-925
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• 2012

On-off control performance of target pumping station was experimented by changing measurement methods for storage level or inflow and operating logic for control system setting. Four scenarios with different measurement methods and operational logic were examined in the Matlab/Simulink environment. Controller's on-off control repetition that was frequent before has been reduced and more effective and stable system operation was found to be possible with the scenarios. Moreover, defensive operation enforced prevention of floods by changing measurement methods enabled economic operation that made an utmost use of storage volumes.