• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.6
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• pp.1-8
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• 2007

Minimizing the cylinder wear and the consumption rate of cylinder oil in a large two-stroke marine diesel engine is of great economic importance. In Korea, authors first developed a motor-driven cylinder lubricator for a Wartsila Switzerland large two-stroke diesel engine. The characteristic of the developed product is that can control automatically the oil feed rate with a load fluctuation by the motor drive and the offset cam. For manufacturing the reliable and useful products, however, it is necessary to investigate further characteristics and to improve performances as a cylinder lubricator. In this study, the effects of pump motor speed, plunger stroke and cylinder back pressure on oil feed rate, maximum discharge and delivery pressures are experimentally investigated by using the electronically controlled quill injection system and distributer in the developed cylinder lubricator. It is found that the oil feed rates of electronic control and mechanical type quills with the in-cylinder back pressure are differently characterized by the role of accumulator, the viscous resistance of contact area, etc. It can be also shown that the maximum discharge pressure of the electronic control quill is lower than the mechanical type one but the maximum discharge pressure difference of two types decreased as plunger stroke is small, and the maximum delivery pressures of two types increased as plunger stroke, motor speed and back pressure are elevated but the maximum delivery pressure of mechanical type is higher than the one of electronic control type.

• Journal of Korea Water Resources Association
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• v.37 no.8
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• pp.675-685
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• 2004

In this study, overflow behaviors through a partially open tainter gate mounted on a standard ogee spillway were investigated by using the FLOW-3D. The results indicated that the discharge coefficient is in the range of 0.685 to 0.723. A relation of gate-controlled discharge to free discharge was proposed and a reasonable correlation between the free and controlled discharge was obtained. Pressures on the spillway crest and the gate were also investigated. As the gate opening rate decreases with a fixed gate opening height and the gate opening height increases at a fixed gate opening rate, negative pressures on the spillway crest and the dimensionless maximum pressures on the gate increase.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.5
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• pp.19-28
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• 2005

It is of great economic importance to minimize the cylinder wear and the consumption rate of cylinder oil in a large two-stroke diesel engine. The motor-driven cylinder lubricator was first developed fur a large two-stroke marine diesel engine made in $W{\ddot{a}}rtsil{\ddot{a}}a$ Switzerland Ltd. by the joint research of industry-university. In this study, the effects of revolution speed, plunger stroke and cylinder back pressure on maximum discharge and delivery pressures, delivery delay duration, and oil feed rate are experimentally investigated by the home-manufactured cylinder lubricator. The maximum discharge pressure with a spot of 0.03 m and the maximum loss pressure at spots of 5, 6.78 and i 0 m away from the end of lubricator slot are increased as plunger stroke, revolution speed and back pressure are elevated, and the delivery delay duration is shortened as plunger stroke, revolution speed and oil pipe length are increased. Also, oil feed rate is increased as plunger stroke and revolution speed are raised, but lowered as the back pressure is increased.

• Applied Science and Convergence Technology
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• v.25 no.6
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• pp.108-115
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• 2016

Even if ion pumps are widely and mostly used in ultra-high vacuum (UHV) conditions, virtually every existing ion pump has its maximum pumping speed around 1E-6 mbar (1E-4 Pa). Discharge intensity in the ion pump Penning cell is defined as the current divided by pressure (I/P). This quantity reflects the rate of cathode bombardment by ions, which underlies all of the various pumping mechanisms that occur in ion pumps (chemisorption on sputtered material, ion burial, etc.), and therefore is an indication of pumping speed. A study has been performed to evaluate the influence of magnetic fields and cell dimensions on the ion pump discharge intensity and consequently on the pumping speed at different pressures. As a result, a combination of parameters has been developed in order to design and build an ion pump with the pumping speed peak shifted towards lower pressures. Experimental results with several different test set-ups are presented and a prototype of a new 200 l/s ion pump with the maximum pumping speed in the 1E-8 mbar (1E-6 Pa) is described. A model of the system has also been developed to provide a framework for understanding the experimental observations.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.6
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• pp.52-60
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• 2012

Minimizing the cylinder wear and the consumption rate of cylinder oil in a large two-stroke diesel engine is of great economic importance. A motor-driven cylinder lubricator for Sulzer RT-flex large two-stroke diesel engines developed by authors is in need of modifying the lubricating system to lubricate cylinder parts optimally by an electronically controlled quill device according to changes of engine load and revolution speed. In order to apply the developed accumulating distributor to an integrated cylinder lubricator by the electronically controlled system as the third research stage, the lubricating system is improved in the electronically controlled quill device with a solenoid valve. In this study, the effects of lubricator revolution speed, driving pressure and cylinder back pressure on oil feed rate, maximum discharge and delivery pressures are experimentally investigated by using the integrated cylinder lubricator system with an accumulated distribution by the electronic control. It is found that the oil feed rate of the developed integral cylinder lubricator system is less than that of the motor-driven cylinder lubricator by the electronically controlled quill system equipped with an accumulating distributor because of the decrease of delivery speed by increasing the maximum delivery pressure in the same experimental condition.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.5
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• pp.112-120
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• 2008

This study has been conducted to investigate the characteristics of flow field and discharge valve motion in a rotary compressor. In this study, a transient three-dimensional numerical analysis using FSI(Fluid-Structure Interaction) model has been employed to analyze the interaction between the discharge valve and the refrigerants in the rotary compressor. It has been observed that two peaks have appeared in the displacement of the discharge valve. The maximum displacement of the discharge valve has been found to be located at the second peak. Also, the input pressure of the refrigerants has been compared with the pressures of the muffler passage and the compressor outlet in the rotary compressor. The pressure has decreased along the pathway in the rotary compressor. And the volume flow rates obtained from the current numerical study have been compared with the experiment at data to verify the validity of the present numerical study. This study may supply the fundamental data for the design of rotary compressors.

• Transactions of the Korean Society of Mechanical Engineers
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• v.1 no.2
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• pp.65-72
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• 1977

Major problems in the design and use of refief valve are (a) chattering because of instability, (b) excessive pressure differential which makes the valves crack far below maximum pressure diminishing useful flow in the system. In this study, A magnet-coupled relief valve is investigated theoretically and experimentally in order to improve the performance of a conventional direct type reliefvalve. A theory is developed to predict the performance, response, and stability of the magnet-coupled valve taking into account the delivery line response. In the experiment, a typical magnet-coupled relief valve is designed on the basis of the analytical results; the discharge rates are measured varying the supply pressure, and both the pressure-time curves and valve displacament-time curves are recorded providing the supply pressures greater than the setting pressure. The measured override characteristic curves are then compared with those of conventional pilot type and direct type releif valves. It is showm that the excessive pressure differential of a magnet-coupled relief valve becomes less than that of a conventional direct type valve. It is also shown that the most important chatacteristic of a magnet-coupled relief valve is to eliminate valve chattering due to instability regardless of the magnitude of setting pressures and discharge rates, which suggests wide applications of the idea of the use of a magnet in the design of hydraulic valves.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.4
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• pp.91-98
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• 2011

Minimizing the cylinder wear and the consumption rate of cylinder oil in a large two-stroke diesel engine is of great economic importance. A motor-driven cylinder lubricator for Sulzer RT-flex large two-stroke diesel engines developed by authors is in need of mounting a quill system to lubricate cylinder parts for smoother operation. In order to apply the common-rail lubricating system to the developed cylinder lubricator as the second research stage, the quill system with a progressively quantitative distributor is improved in the electronically controlled quill system with an accumulating distributor. In this study, the effects of lubricator motor speed, plunger stroke and cylinder back pressure on oil feed rate, maximum discharge and delivery pressures are experimentally investigated by using the electronically controlled quill system with an accumulating distributor in the developed cylinder lubricator. It is found that the oil feed rate of the electronically controlled quill system with an accumulating distributor is larger than that of the quill system with a progressively quantitative distributor because of the increase of delivery speed and volume by changing the location of accumulator in the same experimental condition.

• Journal of Ocean Engineering and Technology
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• v.28 no.6
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• pp.500-507
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• 2014

This study aimed at conducting a flow analysis of the pressure distribution, discharge flow rate, and consequent thrust force according to the rotational speed of a three-dimensional screw propeller, and then investigating the effect of the rotational speed on the characteristics of the screw propeller by varying the relevant speed (3200, 2400, 1600, 800 rpm). In particular, the computational domain was considered by the analysis in the blades and outlet chamber, using boundary conditions. The difference between the minimum and maximum pressures was 5.5 MPa under the given conditions. The discharge flow rate at this pressure difference was on the level of 1956.67 kg/s, as a thrust force of 47083.7 T(N) was obtained. This study showed that the discharge flow rate linearly increased with the rotational speed, proportional to the RPM, while the thrust force was gradually and steadily increased with the relevant speed. In addition, it was proved that the occurrence of cavitation under the given conditions was closely related to the decrease in the durability of the screw propeller because the thrust force depends on the speed.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.8
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• pp.587-590
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• 1999

In this study, it is the purpose to develope a cheap and compact $CO_2$ laser and to apply 60 Hz AC discharges as a new exciting source. An axial and water cooledtype was adopted as the laser mode. The laser performance characteristics as various parameters, such as gas pressure and discharge current, have been investigated. And the laser output and the efficiency of DC and 60 Hz AC discharge-exciting type have been measured and compared for the different input powers at the static operational pressure. As a result, the case of 60 Hz AC discharge-exciting type, the laser oscillation began at the condition of operational pressure 6 Torr and discharge current 5 mA. A maximum laser output of about 32 W was obtained at an operational pressure of 18 Toorr and a discharge current of 30 mA. In addition, the laser output was saturated from an operational pressure of about 14 Torr and a discharge current of about 20 mA. In this $CO_2$ laser, the laser output of 60 Hz AC discharge-exciting type was slightly higher than that of DC discharge-exciting type. And the laser efficiency was about 10 to 13% for the various operational pressures and the discharge currents.