• The KSFM Journal of Fluid Machinery
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• v.14 no.5
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• pp.39-47
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• 2011

Flow control range of valve, which is installed on pipeline, varies according to valve type, pipe diameter, pipe length, roughness, and elevation difference of both ends of pipeline. A lot of computation efforts and knowledge are needed to estimate flow control range of valve, considering above many parameters. The table of flow control range of each valve type is presented for convenience of pipeline design engineers who must make decision of valve size and type in this study. Also the reason that butterfly valve is recommended for flow control, and gate valve is forbidden is presented via quantification and figures in this study.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.240-244
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• 2003

In this paper, we present the CFD and experimental results for flow characteristics as well as pressure fluctuation in a T-type ball valve. In the experiment, flow visualization for the wake is performed with a fluorescent dye. In CFD, the valve flow is simulated three-dimensionally using a commercial fluid analysis code, FLUENT 6.0. FFT analysis to the pressure fluctuation in the wake region is also calculated Analysis results show that the characteristic frequency of the wake flow is strongly dependent on the Reynolds number.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.2_2
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• pp.199-207
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• 2020

These days, many different types of valves are developed in the industrial area according to their use purpose. Multiple kinds of valves are installed to control a flow and pressure of the pipe conveying fluid. Valves serve as critical roles in land plants such as power plants. The performance of equipment varies depending on valve characteristics. In this study, the internal flow analysis on Cone-type valve is conducted to analyze flow field and secure a value of the flow coefficient Cv. According to the internal flow analysis, when the flow distribution of the middle cross-section of valve was open 100%, flow field was relatively and smoothly taken out. If it was open 50%, flow recirculation region increased and a little complex flow field occurred. Unlike ball valve or butterfly valve, this valve had flow recirculation in its outlet depending on a valve opening amount. Therefore, it was found that there was no flow recirculation in the outlet of Cone-type valve.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.2
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• pp.111-119
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• 1997

The operating characteristics of the check valve in the clutch piston of an automatic transmission have a great effect on the shifting performance. This paper addresses the modeling, dynamic analysis, and optimization of the check valve. It was found that the vortex causes a pressure drop, which is related to the rotating speed of the clutch piston, oil volume discharged from the check valve, and valve geometry. Maximizing the oil volume discharged, geometry of the check valve is optimized. The results can be used to design an improved check valve which provides a suitable oil pressure curves for achieving smoother shifting.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.5
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• pp.7-13
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• 2010

Main starting valve is one of the main parts in the control system of diesel engines, purposed for starting main engines. It is composed of ball valve, check valve, actuator, etc. The design axioms provide a general framework for design methodology. Two axioms are independence axiom and information axiom. These axioms can be applied to all design process in a general way. The first axiom is introduced to analyze and evaluate the design of a main starting valve. The design parameters(DPS) are determined sequentially by considering the independence axiom. For the structural design of a main starting valve, the strength is calculated by using finite element method. In addition, the strength of its actuator piston is evaluated.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.3
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• pp.179-187
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• 2009

This paper presents a static and dynamic characteristics of the relief valve which is a kind of direct operated pressure control valve for hydrogen compressor. The valve is consisted of a main poppet, a spring, an adjuster and a valve body. The purpose of this study is development of the simulation model for relief valve by using commercial AMESlM$^{(R)}$ tool. Poppet with sharp edge seat type and ball poppet with sharp edge seat type compare for P-Q characteristic. The dynamic simulation results are presented the operating pressure characteristics of relief valve. High pressure power unit of which maximum pressure control range is 100MPa was manufactured, and the pressure control valve was experimented using the above-mentioned power unit. The new model of pressure control valve from this results was suggested. It was confirmed that the suggested valve has a good control performance from experimental setup.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2251-2256
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• 1994

An experimental study was conducted on water hammer phenomena generated by quick valve operations in piping systems of buildings. Transient water hammer pressure waves were measured for three different types of valves, i. e. a ball valve, a solenoid valve, and on one-touch valve. The effects of flow rate and valve closing time on the maximum water hammer pressure were investigated. Based on the experimental results, general design recommendations were provided to prevent water hammer phenomena in piping systems of high-rise apartment buildings.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.1639-1644
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• 2015

A study on design and structural strength analysis of a positioner in robot overlay welding system of a ball for ball-valves. Turning-unit of positioner modeled, analysis was conducted by assuming the beam. Turning-unit is applied to the stress, it was shown by 366.85MPa when weight of the ball is $9,000kg_f$. This value is higher than the yield strength of the material. Based on the results of previous, it was modeled the turning-unit by modifying. Results of analysis by a modified modeling, The value of stress was confirmed to 296.11MPa. This value is a value lower than the yield strength of the material, it was found to support the weight of the ball.

• Journal of Chest Surgery
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• v.38 no.9 s.254
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• pp.644-647
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• 2005

A free-floating ball thrombus in the left atrium that may cause fatal systemic emboli or left ventricular inflow obstruction, which often resulting in sudden death, is rarely seen. We describe a very unusual case of a patient with a large, free-floating left-atrial ball thrombus who underwent mechanical mitral valve replacement 7 years ago.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.3
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• pp.28-32
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• 2011

The safety of transporting equipment in a cryogenic condition is one of important problems under the circumstances that the application weight of natural gas is gradually increasing. As a larger disaster may be generated by leakage of oil or gas from valves in case of fire occurrence of a ship, the present research applied a numerical analysis method on thermal stress distribution and deformation, etc. to the design of ball valves satisfying fire safety test's specification(API607) to prevent this. In addition, the present research progressed fire safety tests and compared the test result with numerical analysis results. The Max stress by parts was confirmed through thermal analysis of major parts to evaluate safety. The fire safety test was progressed according to the regulation of API607.