• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1195-1200
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• 2008

This study have goal with conceptual design for Offshore Structures of high pressure control valve for localization. Ball valve for development accomplished with flow analysis based on provision of ANSI B16.34, ANSI B16.10, ANSI B16.25 In order to localize the Offshore Structures high pressure control valve. Numerical simulation using CFD(Computational Fluid Dynamic) in order to predict a mass flow rate and a flow coefficient form flow dynamic point of view. The working fluid assumed the glycerin($C_3H_8O_3$). The valve inlet and outlet setup a pressure boundary condition. The outlet pressure was fixed by atmospheric pressure and calculated until increasing 1bar to 10bar. CFD analysis used STAR-CCM+ which is commercial code and Governing equations were calculated by moving mesh which is rotated 90 degrees when ball valve operated opening and closing in 1 degree interval. The result shows change of mass flow rate according to opening and closing angle of valve. Flow decrease observed open valve that equal percentage flow paten which is general inclination of ball valve. Relation with flow and flow coefficient can not be proportional according to inlet pressure when compare with mass flow rate. Because flow coefficient have influence in flow and pressure difference. Namely, flow can be change even if it has same Cv value. The structural analysis used ANSYS which is a commercial code. Stress analysis result of internal pressure in valve showed lower than yield strength. This is expect to need more detail design and verification for stem and seat structure.

• 한국유체기계학회 논문집
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• 제11권3호
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• pp.43-49
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• 2008

The pump control valve is a butterfly valve that has an eccentric rotating axis. It is not only used as a butterfly valve to control the flow rate or pressure, but also as a check valve to prevent backward flow. A new design method of eccentric rotating axis is proposed to design the valve. The height of the rotating axis is determined through flow field analysis. A general purpose of computational fluid dynamics software system, Fluent is used to simulate the fluid flow. Flow field analysis is performed for various heights of the rotating axis and different opening angles of the valve. A characteristic function is defined for estimating the flow characteristics based on the results of flow field analysis. The characteristic function is defined in order to determine the height of the rotating axis. An optimization problem with a characteristic function is formulated to determine the amount of eccentricity. The height of the Totaling axis of the valve is determined through solving the optimization problem.

• 연구논문집
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• 통권29호
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• pp.123-130
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• 1999

Flow divider valve는 한 개의 공급라인에서 두 개 이상의 출력라인으로 유압유를 일정비율로 분배하는 유압제어밸브로서 하중압력이나 공급압력 등에 관계없이 항상 일정비율의 유량분배가 가능해야 한다. 현재 상용제품의 유량분할 정확도는 90~95% 수준이며, 이러한 유량분할오차(Flow dividing error)는 유압시스템에 누적오차로 작용하여 많은 문제점을 야기시키고 있어 보다 고정밀 유량제어가 가능한 Flow divider valve 개발이 요구된다. 본 연구에서는 외력을 고려한 스푸울의 거동을 수치적으로 정확하게 조사하여 Flow divider valve의 동특성을 규명함과 동시에 유량분할 오차를 감소시키는 최적설계방안을 제시하고자 한다. 동특성 해석은 일정한 하중저항을 입력신호로 작용하는 경우에 대해서 제시하였으며, 이때의 고정오리피스와 가변오리피스의 단면적 및 스푸울의 단면적 변화에 따른 동특성의 변화를 조사하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.995-999
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• 2017

제어밸브의 유량계수에 영향을 미치는 인자들을 파악하고 그 영향을 분석하였다. 제어밸브의 유량계수는 레이놀즈 수, 연결 배관의 형상과 표면 조도 등에 영향을 받는다. 따라서 유량계수를 상수로 취급할 수 없다. 그러므로 로켓엔진과 같이 정확한 유량계수를 요구하는 시스템에서 사용할 목적으로 제어밸브의 유량계수를 측정할 때는 실제 사용 환경과 유사한 레이놀즈 수 영역에서, 동일한 조도 및 형상을 가지는 입출구 배관을 사용하여 측정해야 한다.

• 한국산학기술학회논문지
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• 제21권1호
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• pp.387-392
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• 2020

본 논문은 산업용 밸브의 유량제어시스템을 제안하였다. 산업용 밸브는 주로 배관시스템에 장착되어 유량 및 압력 제어에 사용된다. 제어밸브의 구조 및 작동 방식은 설치환경과 작업용도에 따라 상이하다. 밸브는 그 형태에 따라 그루브 밸브, 버터플라이 밸브 및 볼 밸브 등으로 분류되고, 구동방식은 모터를 이용하거나, 유압 및 공압을 이용하는 것이 일반적이다. 제어밸브를 이용한 유량제어시스템은 유량을 계측하여 피드백시스템을 구현하여야 하지만, 본 논문에서는 고가의 유량센서를 사용하지 않고 밸브의 개폐에 따른 유량변화를 실험하여 밸브 전후단의 압력차와 개폐정도를 이용하는 방법을 제안하였다. 밸브의 유량은 유량계수를 이용하여 밸브 전후단의 압력차와 밸브의 개폐정도로 표현할 수 있으므로 이를 이용하여 유량제어시스템을 설계하였다. 제어입력에 따른 밸브의 개폐를 나타내는 전달함수는 신호압축법을 이용하여 구하였으며, 이를 이용하여 밸브 스템의 명령추종성능을 향상시킬 수 있는 외란관측기를 설계하였다. 제안된 제어시스템의 성능을 검증하기 위해 제어밸브 전후단에 압력센서를 장착하여 제안된 제어방법의 성능이 유량센서를 이용한 경우에 준함을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제32권6호
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• pp.923-930
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• 2008

The butterfly valve is widely used in the industrial field as an on-off or a flow control valve. When the butterfly valve is used as a flow control valve. cavitation sometimes occurs in the range of high flow rate because of the small valve opening. Therefore. the pressure loss and the cavitation characteristics are investigated by use of a commercial CFD code. The results show that the possibility of cavitation occurrence in the cryogenic butterfly valve is very high in the case of valve opening angle below 10 degree and incident velocity over 6m/s. By increasing the inlet velocity at 10 degree of valve opening angle. the value of loss coefficient increased. However. by increasing the inlet velocity at 50 degree of valve opening angle. the value of loss coefficient decreased.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.458-462
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• 2004

The hydraulic system for discharging compressed gas is composed of compressor tank, proportional flow control servo valve, expulsion spool valve and discharging tube. Purpose of this study is to control of expulsion spool valve. First, we analyzed the hydraulic system. The flow control servo valve is modeled as a 2nd order transfer function and friction force of the expulsion spool valve is modeled as nonlinear model with stribeck effect. However, it is difficult to include the flow reaction force in modeling. So, we exchanged from the simplified flow reaction force of the compressed gas affection into the flow analysis code written in FORTRAN code. Our simulation of the oil pressure system for discharging gas used MATLAB/Simulink. So, we realized ＆apos;Level -2 S-Function Fortran＆apos; to cooperate for MATLAB/Simulink and FORTRAN code. PD controller is selected to control in this system. Simulation results show that with given conditions the controllers give a good tracking performance.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.156-161
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• 2005

Dynamic flow characteristics of a solenoid valve are affected by pressure difference in inlet and outlet of orifice, gas temperature, and supply voltage of a coil. In this paper, the dynamic flow characteristics for deviations of various conditions are studied Static and dynamic flow for variation on-time of a solenoid valve open signal are measured in basic bench test. The solenoid valve is applied to a compressed natural gas(CNG) engine test for validation of flow control performance. The experimental results show that flow of high pressure gas can controlled precisely by using a solenoid valve.

• Journal of Advanced Marine Engineering and Technology
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• 제19권1호
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• pp.28-35
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• 1995

The fluid flow for a energy transfer is essential for the design and operation of power plants, petrochemical plants and ships including a process. When the operating conditions of a plant are changed or any transitional event occured, the flow controls of a fluid must be performed to follow the new operating state or mitigate the results of a event. Generally these flow controls to accommodate the new operating state of a plant are made by the use of various valves. The refore the design of valves and the related techniques are very important to the system and component designs. However the system and component design are not familiar with the practical theory of the valve since the derivative procedures of the flow equations in a valve are difficult and it is not easy to found the theoretical foundamentals and informations about the design of a valve from the present references. In this study the flow equations applicable to a valve for liquid are theoretically derived in detail. And the definition of valve reynolds number and its boundary values between the tubulent and laminar flow is described compared with the values of a circular pipe flow.

• 한국유체기계학회 논문집
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• 제10권4호
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• pp.61-70
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• 2007

Numerical analysis of three dimensional incompressible turbulent flows in LNG marine high pressure drop control valves was carried out by using the CFD-ACE from ESI-Group. In this study, flow characteristics of control valves with complex flow fields including cavitation effect were investigated. Simulation was performed on five models of control valve that had different orifice diameters of anti-trim and the size of valve. Comparing newly designed control valves for controling the occurrence of cavitation with the conventional valve, new valves showed a improved flow pattern with almost no cavitation.