• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.3
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• pp.111-119
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• 2005

In the magnetic fluid linear pump, the pumping forces and pumping speed mainly depend on the current patterns. In this research, a new design to reduce the discontinuities of the pumping forces of the MFLP was studied. Continuous pumping of the newly designed MFLP by using AC current increases pumping efficiency and reduces the pumping force. Forming shapes of the magnetic fluid at the intermediate state were computed and compared to measurement. Since the back flow of the fluid is reduced remarkably, 4 yoke's AC driving is more efficient than 7 yoke's DC driving. The size, weight and pumping discontinuity are also reduced.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.4
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• pp.237-246
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• 2004

The advantages of the Magnetic Fluid Linear Pump(MFLP) is that this device could Pump the non-conductive. non-magnetic liquid such as Insulin or blood because of the segregation structure of the magnetic fluid and pumping liquid. In this device. the sequential currents are needed to Produce pumping forces so that Pumping Forces and Pumping speed mainly depend on the current Patterns. The excessive forces at Pumping moment could cause the medical shock, and weak forces at intermediate moment could cause the back flow or the pumping liquid. So the ripples of the pumping forces need to be reduced for the medical application. In this research, the driving characteristics in the MFLP by operating current is analysed. The change of magnetic fluid surface according to the driving currents could be obtained be magneto-hydrodynamic analysis so that Pumping fortes could be computed by integration of the surface moving to the pumping direction at each moment. The actual MFLP with 13mm diameter was made and tested for experiments. The effects of driving current and frequency on the pumping forces and pumping speed were analyzed and compared with experimental measurements.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.544-549
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• 2017

This paper aims to examine the effect of rotational fluid motion about the efficiency of the gas - liquid ejector, which is a core unit in a ship equilibrium water treatment system. The ejector is a device for injecting ozone into ship equilibrium by the negative pressure generated by exchange of momentum between water and ozone. The existing ejector ejects the driving fluid with a simple form. In this paper, however, a rotation induction device is applied to the driving nozzle so that the driving fluid can be rotated and injected. To investigate the flow characteristics by the rotational movement of the driving fluid, CFD was used. The pressure and flow rate of the driving fluid, the negative pressure and suction flow rate of the suction fluid in the suction part, and the discharge pressure were predicted. On the basis of the results, the efficiency of the ejector using the rotation induction system was 22.25%, which was about 1.7% better than that of the existing ejector. Finally, to verify the feasibility of the CFD, an experiment was conducted on the ejector using the rotation induction device and the results were similar to those of the CFD.

• Transactions of The Korea Fluid Power Systems Society
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• v.5 no.1
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• pp.1-5
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• 2008

Pneumatic driving systems have hard non-linear characteristic and large friction force compared with driving power. Hence, it cannot be robust against parameter uncertainties, modelling error, disturbance and noise. In this study, we apply a mixed $H_2/H_{\infty}$ control to the generalized plant for a pneumatic driving apparatus system including parameter uncertainty and disturbance. In order to design the $H_2/H_{\infty}$ controller, we use the LMI technique. To evaluate control performance and robust stability of the designed controller, we compare it with a conventional controller such as PVA(Position-Velocity-Acceleration state controller) using the simulation results. As a result, it can be known that designed controller shows better robust stability than the conventional controller.

• Transactions of The Korea Fluid Power Systems Society
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• v.5 no.2
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• pp.1-7
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• 2008

To improve the performance of the bent axis type axial piston pump driven by the tapered piston, it is necessary to know the driving characteristics and mechanism of the tapered piston and the cylinder block. Since each piston not only rotates on its axis and reciprocates in the cylinder bore, but also revolves around the axis of the driving shaft, it is difficult to analyze the driving mechanism theoretically. The theoretical mechanism far the bent axis type axial piston pump is studied by using the geometrical method. The driving range of the tapered piston is determined by theoretical equations. The results show that the cylinder block is driven by one tapered piston in a limited range and the core parameters such as driving factor of the piston and the ahead delay angle influenced performance of the bent axis type axial piston pump.

• The KSFM Journal of Fluid Machinery
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• v.18 no.6
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• pp.81-85
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• 2015

The purpose of this study is to evaluate energy savings for inverter driving multi-stage centrifugal pump. Variable speed driving pump system has high efficiency compared with constant speed driving pump system. Because of difficulty to estimate operating efficiency of variable speed driving pump system, energy saving rates are used to replace operating efficiency. energy saving rates are calculated from pump input power and pump duty cycle. But another researches have used pump duty cycles of each season for energy saving rate. In this study, for estimating energy saving rate more high accuracy, pump duty cycles are measured for 1 year. pump duty cycles, depending on the season and be classified according to the weekday/weekend or during the week day. By this pump duty cycles, Energy saving rate is calculated appropriately.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.8
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• pp.1074-1083
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• 2010

Recently sloshing that fluid in fuel tank is undulating by the external force during motion of automobile, ship and aircraft is greatly affecting by damaging the inside of structure. It's most important to precisely analyze the behavior of fluid by computational fluid dynamics for minimizing the effect of sloshing for the loaded fuel. This study characterized volume of fluid and pressure according to the length and number of vertical baffle and horizontal baffle in fuel tank for Kia Frontier cargo and analyzed for reduction of sloshing during driving on corner and hill by using ADINA-CFD. As a result of analysis, the optimum length for sloshing reduction shows 0.19 m for vertical baffle and 0.08 m for horizontal baffle. And it shows that vertical baffle is better for the reduction effect of sloshing during driving on corners, on the other hand, horizontal baffle is effective and stable during driving on hills.

• Transactions of The Korea Fluid Power Systems Society
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• v.7 no.2
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• pp.13-18
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• 2010

To improve the performance of the bent-axis type axial piston pump driven by the tapered piston, it is necessary to know the driving characteristics and mechanism of the tapered piston and the cylinder block. Since each piston not only rotates on its axis and reciprocates in the cylinder bore, but also revolves around the axis of the driving shaft, it is difficult to analyze the driving mechanism theoretically. The theoretical mechanism for the bent-axis type axial piston pump is studied by using the geometrical method. The driving range of the tapered piston is determined by theoretical equations. The experimental results show that the cylinder block is driven by one tapered piston in a limited range and the core parameters such as driving factor of the piston and the ahead delay angle influenced performance of the bent-axis type axial piston pump.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.4
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• pp.550-556
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• 2008

The aim of this research is to analyze the influence of motive pressure, driving nozzle position and nozzle throat ratio on the performance of ejector. The experiment was conducted in the variation of motive pressure of 0.196, 0.294, 0.392 and 0.490MPa respectively. The position of driving nozzle was varied in difference locations according to mixing tube diameter(0.5d, 1d, 2d, 3d, 4.15d, 5d and 6d). The experimental results show when the nozzle outlet is located at 3d, the flow characteristics change abruptly. It is shown that the suction flow rate and pressure lift ratio of ejector is influenced by the driving nozzle position. At nozzle position location of the Id of mixing tube diameter the performance of ejector gives the best performance.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.15 no.2
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• pp.97-122
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• 2011

Fluid dynamics driven by pumping without valves (valveless pumping) shows interesting physics. Especially, the driving function to generate valveless pump mechanism is one of important factors. We consider a closed system of valveless pump which consists of flexible tube part and stiffer part. Fluid and structure (elastic tube) interaction motions are generated by the periodic compress-and-release actions on an asymmetric location of the elastic loop of tubing. In this work, we demonstrate how important the driving forcing function affects a net flow in the valveless circulatory system and investigate which parameter set of the system gives a more efficient net flow around the loop.