• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.4
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• pp.251-258
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• 2011

The objective of this study is to propose two empirical correlations to predict the mass flow rate through an automotive block type thermostatic expansion valve and then to evaluate the correlations. The first correlation is deduced by modifying the basic equation of the orifice meter for the mass flow rate and the second correlation is deduced by using the Buckingham's ${\pi}$ theorem. The first correlation showed very good agreement on the measured data for R134a, given by Monforte. Average relative deviation and standard deviation of it are 2.5% and 1.6%, respectively. The second correlation agreed on the same measured data with a little greater deviations. The two correlations may apply to common expansion valves which have different geometrical sizes of the same shape.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.387-392
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• 2020

This paper proposes a flow-rate control system for industrial valves. Industrial valves are used in piping systems to control the flow rate and pressure. In general, valves used in pipelines are classified into globe valves, butterfly valves, and ball valves according to the shape. Motor, hydraulic, and pneumatic systems are used for operating valves. The flow meter should measure the flow rate when configuring the flow-rate control system. On the other hand, because the flow rate of the valve can be expressed by flow coefficient, a control scheme is proposed using the pressure deviation, which measures at the front and rear of the valve. The transfer function for the valve, according to the control input, was estimated using the signal compression method. Based on the induced transfer function, the disturbance observer was designed to improve the command following the performance of the valve stem. The performance of the proposed control method is compared with the flow-rate control result using the flow meter used.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.5
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• pp.545-551
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• 2009

In naval architecture and offshore engineering, the development and a broad use has been achieved in the field of flow control valves for pipe system. Butterfly valves are also widely used for flow control, but there are not many studies for triple-eccentric butterfly valves. Moreover, if the fluid of pipeline flows in the bi-direction then it makes more complicate to adapt triple-eccentric butterfly valves to flow control. In this study, we are trying to develop a bi-directional triple-eccentric butterfly valve through sealing mechanism and stem design study. Digital mockup using 3D CAD was constructed for shape interference check and structural analysis was conducted for structural safety. Also we performed leakage test to check out the durability of the bi-directional pressure for the developed valve.

• Journal of Mechanical Science and Technology
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• v.19 no.9
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• pp.1761-1772
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• 2005

In blood flow passing through the mechanical heart valve (MHV) and elastic blood vessel, hemolysis and platelet activation causing thrombus formation can be seen owing to the shear stress in the blood. Also, fracture and deformation of leaflets can be observed depending on the shape and material properties of the leaflets which is opened and closed in a cycle. Hence, comprehensive study is needed on the hemodynamics which is associated with the motion of leaflet and elastic blood vessel in terms of fluid-structure interaction. In this paper, a numerical analysis has been performed for a three-dimensional pulsatile blood flow associated with the elastic blood vessel and curved bileaflet for multiple cycles in light of fluid-structure interaction. From this analysis fluttering phenomenon and rebound of the leaflet have been observed and recirculation and regurgitation have been found in the flow fields of the blood. Also, the pressure distribution and the radial displacement of the elastic blood vessel have been obtained. The motion of the leaflet and flow fields of the blood have shown similar tendency compared with the previous experiments carried out in other studies. The present study can contribute to the design methodology for the curved bileaflet mechanical heart valve. Furthermore, the proposed fluid-structure interaction method will be effectively used in various fields where the interaction between fluid flow and structure are involved.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.1
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• pp.87-95
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• 2016

In this study, we develop a model of an open center and load-sensing system and for a main control valve to analyze system characteristics and efficiency using SimulationX. In order to analyze the operating characteristics of the pressure and flow of the main control valve of an open center system, a test was performed at each port. The reliability of the model was confirmed by comparing the similarity of the analysis results with the test results before analyzing the operating characteristics of the system. Development of the load sensing main control valve was performed by adding a flow sharing valve and a notched shape to the open center system based on it's the proven reliability. The authors performed the simulation under the same load conditions in order to compare the efficiency of the systems. Additionally, the combined operation performance was investigated by means of analyzing the characteristics of flow distribution under different load conditions.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.8
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• pp.891-898
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• 2005

Inertia welding is a solid-state welding process in which butt welds in materials are made in bar and in ring form at the joint race, and energy required lot welding is obtained from a rotating flywheel. The stored energy is converted to frictional heat at the interface under axial load. The quality of the welded joint depends on many parameters, including axial force, initial revolution speed and energy amount of upset. working time, and residual stresses in the joint. Inertia welding was conducted to make the large exhaust valve spindle for low speed marine diesel engine. superalloy Nimonic 80A for valve head of 540mm and high alloy SNCrW for valve stem of 115mm. Due to different material characteristics such as, thermal conductivity and flow stress. on the two sides of the weld interface, modeling is crucial in determining the optimal weld geometry and Parameters. FE simulation was performed by the commercial code DEFORM-2D. A good agreement between the Predicted and actual welded shape is observed. It is expected that modeling will significantly reduce the number of experimental trials needed to determine the weld parameters. especially for welds for which are very expensive materials or large shaft. Many kinds of tests, including macro and microstructure observation, chemical composition tensile , hardness and fatigue test , are conducted to evaluate the qualify of welded joints. Based on the results of the tests it can be concluded that the inertia welding joints of the superalloy exhaust valve spindle are better properties than the material specification of SNCrW.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.15-20
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• 2017

The main purpose of the ball valve ball is to be moved by the rotation of the stem when fully open or completely closed. In this study the heat of the initial model, which used a structure interaction analysis technique, tried to examine the structural safety of the high temperature for the ball valve. In the initial model the stress of the exiting sheet was more than the yield strength. We selected two design shapes with variables of length and thickness for the optimization of the sheet. The Kriging interpolation method was applied to a meta-model-based optimization technique. As a result, it was possible to find a thickness and length for the sheet within the yield strength. This was done by measuring the value of the capacity coefficient of the valve and evaluating the performance of the ball valve.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.6_2
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• pp.773-779
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• 2021

CNG, which has recently been attracting attention as an alternative fuel in the transportation field to reduce emissions caused by global warming, is natural gas with abundant reserves and mainly composed of methane. Being in a gaseous state, natural gas requires the compression and liquefaction processes for transportation. Until now, general shut-off valves for liquid and gas piping have been developed in Korea, but there are few studies on shut-off valves for high pressures of about 200 bar. Currently, research on the flow analysis of valves is being actively conducted around the world. However, there are relatively many studies on large valves such as low-pressure valves or shipbuilding and marine, and the safety factor through structural analysis to check the structural integrity of the valve is checked at the design stage. Since it is necessary to have a fast response speed while minimizing pressure and speed loss due to flow change, basic research was conducted on the flow analysis of the valve to secure design data, and the numerical analysis was performed on high-pressure automatic shut-off valves applied to CNG refueling stations. After securing the basic valve shape through reverse engineering for advanced products, we compared the valve flow coefficient Cv coefficient with advanced products. As a result, it was found that the reverse engineering model was at the level of about 60%. However, we compared the Cv coefficient by modifying the reverse engineering model, and the result showed that it was improved to about 96%.

• Proceedings of the Korean Magnestics Society Conference
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• 1998.05a
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• pp.52-53
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• 1998

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1391-1392
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• 2013