• Journal of Korea Water Resources Association
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• v.40 no.8
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• pp.665-675
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• 2007

An equation is developed to estimate potential groundwater resources available for development. This equation is useful for preliminary planning stages prior to detailed design stages. The equation is a function of major factors such as aquifer characteristics, saltwater intrusion length, coastal groundwater discharge and potential locations of pumping wells. Thus, most important factors are taken into account. The equations are derived using well-known analytical solutions. Thus, the basis is scientifically sound. Use of the equation is quite simple since it is an explicit function of variables. A logical method is proposed to assess a radius of influence of a pumping well considering aquifer characteristics and the pumping rate. Applications to a hypothetical problem and comparison with results from a more rigorous numerical simulation model indicate that results obtained from the proposed equation are conservative.

• Journal of Environmental Science International
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• v.28 no.9
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• pp.737-749
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• 2019

In this study, the sensitivity analysis of hydraulic conductivity and separation distance (distance between injection well and pumping well) was analyzed by establishing a conceptual model considering the hydrogeologic characteristics of facility agricultural complex in Korea. In the conceptual model, natural characteristics (topography and geology, precipitation, hydraulic conductivity, etc.) and artificial characteristics (separation distance from injection well to pumping well, injection rate and pumping rate, etc.) is entered, and sensitivity analysis was performed 12 scenarios using a combination of hydraulic conductivity ($10^{-1}cm/sec$, $10^{-2}cm/sec$, $10^{-3}cm/sec$, $10^{-4}cm/sec$) and separation distance (10 m, 50 m, 100 m). Groundwater drawdown at the monitoring well was increased as the hydraulic conductivity decreased and the separation distance increased. From the regression analysis of groundwater drawdown as a hydraulic conductivity at the same separation distance, it was found that the groundwater level fluctuation of artificial recharge aquifer was dominantly influenced by hydraulic conductivity. In the condition that the hydraulic conductivity of artificial recharge aquifer was $10^{-2}cm/sec$ or more, the radius of influence of groundwater level was within 20 m, but In the condition that the hydraulic conductivity is $10^{-3}cm/sec$ or less, it is confirmed that the radius of influence of groundwater increases sharply as the separation distance increases.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.116-118
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• 2005

열공압 방식으로 동작하는 마이크로 펌프와 밸브가 집적된 (polydimethylsiloxane)PDMS 미 세 유체 시스템을 제작하였다. 본 실험에서 제안한 미세 유체 시스템은 PDMS 마이크로 채널, PDMS membrane, 열공압 챔버, indium tin oxide(ITO) 히터로 구성되어 있다. 마이크로 펌프의 경우 가해주는 펄스 전압의 변화를 통해 유속을 최적화 하였고 마이크로 밸브의 경우 가해주는 직류 전압을 변화시켜 유체의 흐름을 제어할 수 있었다. 미세 유체 시스템의 최적화된 조건은 마이크로 펌프의 경우 duty 4%와 주파수 4Hz에서 최대 pumping rate을 나타냈고 그때의 pumping rate 68nl/min이었다. 마이크로 밸브의 유체를 closing 전력은 450mW이었다.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.680-686
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• 2004

Recently, the application of variable geometry turbocharger (VGT) to the high speed direct injection (HSDI) diesel engine has gained more and more interest in automotive industry. A steady state experimental investigation has been undertaken on a 1.5L HSDI diesel engine to verify the benefits of VGT comparing to the standard engine having a waste gate turbocharger (WGT). Specifically, part load performances (e.g., fuel economy and emission) have been investigated under various vane angles of the VGT. The results show that the real exhaust gas recirculation (EGR) rate as well as the pumping loss is very important to improve break specific fuel consumption (BSFC). It was previously known that the pumping loss only is a main parameter. In addition, the trade-off relationship between BSFC and NOx according to boost pressure, and the decreasing tendency of NOx with increasing real EGR rate have been verified. 1-D numerical analysis also has been performed, and the numerical results are in good agreement with experimental results.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.119-124
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• 2006

This paper deals with energy-saving effort in the hydraulic power steering system. Commonly, the hydraulic power steering systems are used for passenger cars and the reduction of pumping loss under non-steering condition is important to improve fuel economy. Experiments and simulations are performed simultaneously to examine the main factors to reduce the pumping loss-pressure loss and flow rate of the power steering systems. Fuel economy effect of the optimal design of power steering system is verified by vehicle test - more than 1% fuel consuming reduction is attained.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.12
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• pp.606-610
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• 2006

We investigated the output characteristics of Nd:YAG lasers at wavelength of 1444 nm, which were pumped by 450 Xe-flashlamp, 700 torr Xe-flashlamp and 700 torr Kr-flashlamp. With a Xe-flashlamp of 700 torr of gas pressure, the pulse energy of 0.738 J was obtained with repetition rate of 9.16 Hz and pumping pulse width of 400 ms. In case pumping pulse width of 5 ms and repetition rate of 1 Hz, 700 torr Kr-flashlamp showed the highest pulse energy of 1.44 J.

• Korean Journal of Optics and Photonics
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• v.1 no.2
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• pp.204-209
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• 1990

The temperature variation at a laser rod center induced by high repetetion rate pumping was measured by counting the number of inteference frigne shift and found to be consistent with the theoretical value obtained from heat diffusion equation. The spatial homogeneity and energy transfer rate of flashlamp pumping by the single elliptical reflector plated with gold were evaluated by measuring interference fringes oever the cross section of a Nd:YAG laser rod.

• Journal of Welding and Joining
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• v.22 no.1
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• pp.58-64
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• 2004

The control of the weld bead shape is important in laser welding of the small parts. The effects of laser welding parameters on the weld bead shape in the pulsed Nd:YAG laser welding of STS 304L material were investigated. Shielding gas type, flow rate, pumping voltage, pulse frequency, pulse width, focal position and overlap distance were selected as laser welding parameters. Experiments were designed and conducted using the Taguchi method which was a statistical experimental method. The weld bead width, penetration, area and aspect ratio were measured and analysed as the weld bead shape properties and the welding parameters were optimized to maximize the weld aspect ratio. Weld aspect ratio were greatly affected by the pulse width, pumping voltage and pulse frequency, and somewhat by the overlap distance, and little by the shielding gas type, flow rate and focal position. A confirmation experiment were conducted using the optimized welding parameters.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.93-99
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• 1998

We present a novel micropump of which pumping mechanism is based upon MHD (Magnetohydrodynamic) principle. The MHD micropump uses Lorentz force as pumping source. In the MHD micropump, Lorentz force is applied into initially stagnant conducting fluid to drive it in magnetic and electric field to flow in both directions. The performance of the MHD micropump is obtained by measuring the pressure head difference and flow rate as applied voltage changes from 10 to 60 V DC at 0.19 and 0.44 Tesla. The pressure head difference is 18 mm at 38 mA and the flow rate is 63 ${\mu}{\ell}$ /min at 1.8 mA when the inside diameter of inlet/outlet tube is 2 mm and the magnetic flux density is 0.44 Tesla.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.5
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• pp.769-777
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• 2016

The objective of this study was to evaluate the stream depletion from groundwater pumping in deep aquifer using the Ward and Lough's analytical solution (2011) which considers a two-layer leaky aquifer system. The calculated results for each pumping from the 110 wells beside streams showed a wide range of non-dimensional stream depletion, that is the streamflow depletion rate divided by the groundwater pumping rate, from lower than 0.1 to more than 0.9 on average for 5 years depending on the specific properties of well location. From the comparison with Hunt's solution (1999) of a single layer aquifer, the Ward and Lough's solution showed about 50% lower than the Hunt's solution due to the difference of hydraulic properties between the first and second layers as well as the lagged effect of vertical leakance. It was also found that the groundwater pumping has a minor effect on the stream depletion if the stream depletion factor (SDF) of the 1st layer is higher than about 1,000 or the SDF of the 2nd layer is higher than about 100, or the vertical leakance is smaller than $10^{-5}s^{-1}$. Furthermore, in the present study, the variations of the stream depletion were assessed according to the magnitude of unmeasured hydraulic properties such as transmissivity and storage coefficient of the 1st layer, vertical hydraulic conductivity of the 2nd layer, the streambed hydraulic conductance.