• Progress in Superconductivity and Cryogenics
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• v.11 no.1
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• pp.39-44
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• 2009

We proposed a linear type magnetic flux pump (LTMFP) as a power supply for superconducting magnet system. In order to explain the operating mechanism of pumping action, the pumping sequence based on penetrated position and moving speed of magnetic flux on the superconducting Nb foil should be understood. In this paper, we induced a theoretical equation for pumping current of LTMFP according to the position of normal spot and corresponding equivalent circuit. In addition, current charging tendencies under the intensity of magnetic flux and frequency were described based on the theoretical pumping equation.

• Water for future
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• v.12 no.2
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• pp.36-42
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• 1979

This study has been conducted to find out the location and amount of the subterrain water body developed in the alluvial stratum in Paho-Dong, Sungsee-Myo-n, Dalsung-Kun are. An earlier test drilling was done in this area by R.O.K. Agricultural Promotion Corporation. The area consists of a small river basin and surrounding low hills developed around the junction of the Nakdong and Kumho Rivers. The strata of this area are made of Paldal gravel, Bokhyundong and Banyawol layers which were formed in the cretaceous period of the Meso-saicera or acid dikes and covered with-irregular alluvial layers. The alluvial layer in this area is composed of rather minute particles and proportional electric resistance tests on this layer show $10^2\;-\;10^3\;\Omega/cm$. The drillings up to 12meters deep showed only the sand layer (Form 3 to 26meters in thickness) contains water. The sand layers can not be considered a good water trapping one. Applying the data from the drillings to A.Hazen's equation, $K\;=\;{cd_e}^2\;(0.7\;+0.03t)$ to get the theoretical value of the water infilterated, I calculated it as K=13.92m/day. And again the value was set to Dupuit equation, (equation omitted) to acquire the pumping water amount the result was $Q_1\;=\;77.20\;\textrm{m}^3/day$. When the data-applied to the equation for pumping water amount, (equation omitted), the results were $Q_2\;=\;122.39\;\textrm{m}^3/day$ and K = 38m/day $Q_1\;and;Q_2$ (tow types of pumping water amount) represent proper value decrease and maximum value decrease respectively. Therefore, $Q_2$ is the least amount of water we can pump. The area covers about $1,555,000\;\textrm{m}^2$ and the maximum water needed in this area amounts to $155,000\textrm{m}^3$. That means we have to drill 1,406 pumping wells. It is concluded that undertaking the project in this area is irrational or even desperate and surface water should be developed more favorably.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.04a
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• pp.204-209
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• 1997

This paper reports on the theoretical study of the vane motions in a positive displacement vane pump. Vane detachment cause the pressure fluctuation, noise, wear in cam ring, and decrease the volumetric efficiency. Dynamic equation of vane motion and flow continuity equation have been modeled and solved simultaneously using 4th order Runge-Kutta method. As results of analysis, vane detachment occurs due to pressure overshoot by excess compression in the pumping chamber. Amount of vane detachment has been reduced by decreasing the pressure overshoot.

• Progress in Superconductivity and Cryogenics
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• v.11 no.2
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• pp.20-24
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• 2009

In order to explain the operating characteristics of LTMFP in a wide range of driving frequency, an analytical equation that takes into account the detailed behavior of the normal spot is necessary. In this paper, based on the phenomenon of magnetic diffusion of the superconductor we modified the theoretical equations for pumping action in LTMFP. The modified equations explained well the pumping actions under the different load magnets. These results are important to explain the pumping tendency of the LTMFP according to driving frequency.

• The Journal of Engineering Geology
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• v.4 no.2
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• pp.219-229
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• 1994

Since groundwater flow in fractured rocks is controlled by the distribution of fractures irregu1arly developed in space, it is not possible to understand the hydraulic characteristics of fractured aquifers using Theis equation which is applicable only to homogeneous isotropic confined aquifer. This study deals with the theoretical background of the fractal groundwater flow model with leakage, the methodology of calculation of the hydraulic parameters, and the application of the developed model to field data. From the result of the application of the fractal model to two field data in Hongcheon and Yusung areas, we obtained a good match between theoretical curves and observed curves, with the same hydraulic parameters at the pumping well and the observation well. In the two pumping test analyses, we have determined 1.9 of the fractal dimension. This means that the dimension of groundwater flow at these two sites is slightly smaller than radial flow.

• 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 Advanced Marine Engineering and Technology
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• v.10 no.1
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• pp.74-84
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• 1986

Ejectors, having no moving, lubricating and leaking parats, are widely used as marine pumps because of its high working confidence. For instance, uses in ships are stripping in crude oil tank, bilge discharge in engine room, ballast water pumping on are carrier, and brine discharge from fresh water generator. And it is also used as cooling water recirculating pump in boiling water type nuclear reactor and deep-well pump. It is not easy to determine the optimal dimension for designing each ejector agreed with its suggested performance condition, because complicated calculations must be repeated to obtain the maximum efficiency affected by flowrate ratio, head ratio, area ratio and so on. Therefore, it is considered that the CAD (Computer-Aided Design) for ejector is a powerful method for design according to the individual design condition. In this paper, a computer program for water ejector design is developed based on the previous paper on theoretical analysis and experimental results for water ejector. And from the theoretical approach, an equation for the working limit and an equation for determing the shape of throat are obtained. The validity of the present computer program is sufficiently confirmed through the comparison of the computed results with the main dimension of the previous manufactured water ejector. This program will be easily developed as the CAD for various kinds of ejectors, including steam ejector.

• Journal of the Korean Chemical Society
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• v.33 no.2
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• pp.168-176
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• 1989

Theoretical analysis of HF chemical laser models are performed through chemical reaction kinetics, gain process and stimulated emission process. A chemical laser of F+$H_2$ nonchain reaction is investigated through V-R transitions of excited HF for vibrational levels up to v = 3 and rate equations including nonchain pumping and deactivation. On this analysis, harmonic and anharmonic vibrational levels are considered separately and the results of the corresponding power calculations are showed very small difference between the two. Output powers are calculated with variation of temperature and initial concentrations of $H_2$. A HF chemical laser of $H_2$+$F_2$ chain reaction is also simulated with a premixed initial condition. Results of present model calculations are satisfactory through comparison with detailed calculations reported by others.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.8
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• pp.1128-1138
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• 2000

Pumping action in ejector systems is generally achieved through the mixing of a high-velocity and high-energy stream with a lower-velocity and lower-energy stream within a duct. The design and performance evaluation of the ejector systems has developed as a combination of scale-model experiments, empiricism and theoretical analyses applicable only to very simplified configurations, because of the generic complexity of the flow phenomena. In order to predict the detailed performance characteristics of such systems, the flow phenomena throughout the operating regimes of the ejector system should be fully understood. This paper presents the computational results for the two-dimensional supersonic ejector system with a second throat. The numerical simulations are based on a fully implicit finite volume scheme of the compressible Reynolds-averaged Navier-Stokes equation in a domain that extends from the stagnation chamber to the diffuser exit. For a wide range of the operating pressure ratio the flow field inside the ejector system is investigated in detail. The results show that the supersonic ejector systems have an optimal throat area for the operating pressure ratio to be minimized.