• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.1123-1126
• /
• 2003

In this research 4 plate type ER-Valves which have same surface but different width and length are designed and an experimental apparatus is constructed. With this experimental apparatus, flow rate and pressure drop of ER fluid flowing in ER-Valve are measured by varying electric field strength of ER-valve, and relation between valve types and pressure drop is also experimented. ER fluid is made silicon oil mixed with 40wt% starch having hydrous particles. The pressure drop according to the strength of electric field by differential pressure gauge in the present ER-Valve was used. This test reviewed experiment for the special changes of ER fluids in the steady flow condition.

• Journal of Chest Surgery
• /
• v.55 no.2
• /
• pp.177-179
• /
• 2022

Barlow's disease with mitral annular calcification encompassing the subvalvular apparatus, including the valve leaflet and chordae, is extremely rare, and mitral valve repair in such cases is challenging. We report a case of a 60-year-old woman with mitral valve regurgitation that was successfully controlled by resecting the rough zone of P2 and calcifications on the excess leaflet regions and subvalvular apparatus, while retaining the calcification of P3 and implanting artificial chordae and an annuloplasty ring. Mitral valve repair for such cases requires an individualized and compounded surgical strategy for the technique to treat Barlow's disease and manage calcification to control mitral regurgitation.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.12 no.6
• /
• pp.29-35
• /
• 2003

In this research 4 plate type ER-Valves which have same surface but different width and length are designed and an experimental apparatus is constructed. With this experimental apparatus, flow rate and pressure drop of ER fluid flowing in ER-valves are measured with varying electric field strength of ER-valve, and relation between valve types and pressure drop is also experimented. ER fluid is made silicon oil mixed with 40wt% starch having hydrous particles. If we allow the same electric field in the ER-Valve, we came to how that the pressure drop is effected by the electrode length and electrode width. When the strength of the electric field increased, the pressure drop happened big and the flow rate decreased.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.3
• /
• pp.61-67
• /
• 1998

Rapid prototyping becomes widely used in design and manufacturing of mechanical and aerospace engineering. Here a drag valve disk consisted of complicate configuration has designed by CAD, and prototyped by a stereolithography apparatus (SLA) to confirm the design configuration. Also the prototyped valve disk was used for checking if it could be applied for casting from the view point of accuracy, cost, and time. The rapid-prototyped disk by SLA was compared with a high-speed machined disk by MAKINO V55, and it is found that the prototyping of the disk by SLA appears more economical, more accurate and faster than by machining with MAKINO V55.

• Journal of Mechanical Science and Technology
• /
• v.20 no.7
• /
• pp.993-1001
• /
• 2006

In this paper, a method of accurate position control using a pneumatic cylinder driving apparatus is presented. To overcome the effect of friction force and transmission line, low friction type cylinder applied externally pressurized air bearing structure is used and two control valves attached both side of the cylinder directly. To compensate nonlinear characteristics of control valves, linearized control input derived from the relation between control input and effective area of control valve, and dither signal are applied to the valve. The controller applied to the pneumatic cylinder driving apparatus is composed of a state feedback controller and a disturbance observer. Experimental results show that the effectiveness of the proposed method and position control error of $5{\mu}m$ accuracy could be obtained easily.

• Journal of Drive and Control
• /
• v.12 no.4
• /
• pp.21-27
• /
• 2015

The accurate position control of pneumatic driving apparatus is considered in this paper. In pneumatically actuated positioning systems, accurate positioning as an electrical servo has been known to be difficult because of the friction force and compressibility of the air. For good control performance of the pneumatic system, an actuator mounted with externally pressurized air bearings is produced to compensate for friction force. For the controller design, the governing equation of the pneumatic driving apparatus is derived. In order to reduce the nonlinear characteristics of the control valve, linearized control input is derived from the relation between the effective area of the valve and the control input. The experimental results are presented to show the results of the improved position control of the pneumatic driving apparatus.

• 유공압시스템학회:학술대회논문집
• /
• 2010.06a
• /
• pp.18-24
• /
• 2010

Because of the increasing demand on the high precision and high response of a machinery, electronic control valves are widely adopted at various application fields. This paper studies on the static characteristic of a first-stage proportional pressure control valve. At first an experimental apparatus including hyd. pump variable speed inverter, pressure and data aquisition system was setted up with the experimental apparatus, various tests such as P-Q-W test, hyd, pump, dynamic, static, frequency response test of the proportional valve was carride out and the results are discussed.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.4 no.1
• /
• pp.218-228
• /
• 1996

The behaviors of the mixture at the downstream of throttle valve in a TBI type gasoline engine plays a greater role in design of intake system. A good mixture has been influencing directly not only on the engine power but also on the pollutant emission. The mixture flow in an intake manifold is very complex, and the flow characteristics are varied with the valve type, valve angle, inlet air flow rate, and the other flow factors. Three kinds of valve are chosen in this study, and the informations of the mixture flow are observed experimentally using a PIV apparatus. Perforate valve has a smaller recirculation zone than the case of solid valve with a lower valve loss coefficient, and iti is verified that the perforated valve is also suitable to control the flow rate in a mixture flow system.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.27 no.2
• /
• pp.168-174
• /
• 2017

In this work, a piezostack single-stage valve (PSSV) system is proposed and its control performance is experimentally evaluated at high temperature up to $150^{\circ}C$. In order to achieve this goal, a PSSV system is designed and operating principle and mechanical dimensions are discussed. A displacement amplifier and an adjust bolt are used to generate target displacement and to compensate thermal expansion. Then, an experimental apparatus is constructed to evaluate control performance of the PSSV system. The experimental apparatus consists of a heat chamber, a hydraulic circuit, a pneumatic circuit, pneumatic-hydraulic cylinders, thermal insulator, electronic devices, sensors, data acquisition (DAQ) board and a voltage amplifier. The flow rate and displacement control performance of the valve system are evaluated via experiment. The experimental results are evaluated and discussed at different temperatures and frequencies showing the controlled flow rate and spool displacement.

• Journal of the korean Society of Automotive Engineers
• /
• v.11 no.6
• /
• pp.57-67
• /
• 1989

This paper deals with the experimental study of the turbulent flow fields by the hot-wire anemometer and the density fields by the Schlieren photography. In this study, the air mixed with CO$_{2}$ was used to visualize and to study this process and experimental parameters used were valve lift and valve shape. The results obtained are as follows: 1) The axial velocity of mixture flow passing a valve is changed greatly by valve seat angle and valve lift. Especially, it is changed more when the valve seat angles is 30.deg. and 45.deg. than when these are 60.deg. and 90.deg. 2) Experimental results by hot wire anemometer and Schlieren apparatus are very close together. The most satisfactory results are shown when the valve seat angle is 45.deg.