• Journal of Power System Engineering
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• v.7 no.3
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• pp.69-73
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• 2003

In this paper, the relation between displacement of piezoelectric disk and electric field was proposed. From Navier-Stokes equation and Reynold's equation, the relation between flow and gap of plate was determined. This models were further verified by experiments. Based on theoretical study and experimental verification, the proposed model between flow rate and voltage can be used in the design of mass flow controller in gas supplying system.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.317-324
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• 1999

The present work is an attempt to calculate the steady state pressure and perturbed pressure of herringbone grooved journal bearings. A generalized coordinate system is introduced to handle the complex bearing geometry. The coordinates are fitted to the groove boundary and the Reynold's equation is transformed to be fitted to this coordinates system using the Gauss divergence theorem. This method makes it possible to deal with an arbitrary configuration of a lubricated surface. The characteristics of finite herringbone grooved journal are well calculated using this method.

• Tribology and Lubricants
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• v.16 no.6
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• pp.432-439
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• 2000

The present work is an attempt to calculate the steady state pressure and perturbed pressure of herringbone grooved journal bearings. A generalized coordinate system is introduced to handle the complex bearing geometry. The coordinates are fitted to the groove boundary and the Reynold's equation is transformed to be fitted to this coordinate system using the Gauss divergence theorem. This method makes it possible to deal with an arbitrary configuration of a lubricated surface. The caharacteristics of finite herringbone groove journal bearing are well calculated using this method.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.200-202
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• 2003

In this paper, Gauss filter function is used to filter the N-S equation and the subgrid-scale Reynold stresses model is introduced to deduce the practical form of LES equation for 2-D case for flow calculation of hydraulic machine. Then the LES equation and its discrete form in computational field are obtained in the body-fitted coordinate system and the numerical calculation program is built. The incompressible turbulent flow in double-flow-conduits-sewage pump impeller is computed by using the abovementioned program, and then the distribution rules of velocity and pressure in flow field are obtained. Based on this, the designs of double-flow-conduits-sewage pump impeller are optimized.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.1
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• pp.27-33
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• 2012

The relationship between the excitation frequency and the vortex shedding frequency is analyzed during the oscillation of the circular cylinder. Two-dimension unsteady Navier-Stoke's equation is calculated by using the Optimized High Order Compact (OHOC) scheme. The flow condition is Mach number 0.3 and Reynold's number 1000. From the results acquired by calculation, it can be inferred that, when the excitation frequency is near the vortex shedding frequency at the fixed cylinder wake, the oscillation frequency of lift and drag coefficients appears to lock-on. The lock-on refers to a phenomenon in which the aerodynamic coefficient appears as one primary oscillation frequency through excitation and its amplitude is amplified. In the non-lock-on zone, the excitation frequency is not in the lock-on mode anymore and beat is formed in which two or more primary oscillation frequencies of the aerodynamic coefficient are mixed together.

• Tribology and Lubricants
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• v.19 no.4
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• pp.195-202
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• 2003

Many computational researches have been performed about EHL film thickness in the contact between cam and follower in the engine valve train system. However, those computations do not explain the characteristics of dynamic film thickness which means squeeze film effect. Without the consideration of transient term in the Reynold's equation, the predicted film thickness from steady state condition has large difference from the actual film thickness. In this study, we have investigated the kinematic and dynamic simulations of rocker-arm valve train system. From the dynamic simulation, the applied load and the entraining velocity of the lubricant between cam and follower are obtained and with these values the dynamic film thickness is computed by Newton-Raphson method and compared with the steady state film thickness.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.772-777
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• 2013

This article presents the reduction of vibration generated by an automobile fuel pump. In order to analysis the vibration of the fuel pump, a simplified dynamic model is established, which is composed of a rigid rotor and a equivalent springs. The equivalent stiffnesses of the upper and lower assemblies are evaluated by the comparison of modal testing results and the finite element analysis. the stiffness for the oil film of the journal bearing is extracted by using Reynold's equation. In addition, the time responses for the vibration of the fuel pump are computed by using a commercial multi-body dynamics software, RecurDyn. Based on these results, some design suggestions are proposed to reduce the vibration of an automobile fuel pump.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.4
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• pp.522-527
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• 2008

On designing of hydrostatic bearing, load, quantity of oil, stiffness and friction load are considered as basic characteristics. For the analysis of these basic characteristics, pressure distribution by oil film is obtained. Speed of piston, clearance, leakage of oil, eccentricity, shape and roughness of bearing affect the results which are the analysis of basic characteristics of load, quantity of oil, stiffness and friction load. The relationship among those factors are required for optimum designing of hydrostatic bearing for machining tool. Reynold's Equation is calculated through finite element method. Load, leakage of quantity and pressure distribution as variation of length, land length ratio, eccentricity and axial velocity of bearing are investigated. Then optimum design variables are obtained.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.397-405
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• 2000

Many computational researches have been performed about EHL film thickness in the contact between cam and follower. However, those computations do not explain the characteristics of dynamic film thickness which means squeeze film effect. Without the consideration of transient term in the Reynold's equation, the predicted film thickness has large difference from the actual film thickness. In this study, we have investigated the kinematic and dynamic simulations of rocker-arm valve train system. From the simulation, the applied load and the entraining velocity of the lubricant between cam and follower are obtained and with these values the dynamic film thickness is computed by Newton-Raphson method and compared with the steady state film thickness.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.6
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• pp.520-526
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• 2013

This article presents the reduction of vibration generated by an automobile fuel pump. In order to analyze the vibration of the fuel pump, a simplified dynamic model is established, which is composed of a rigid rotor and a equivalent springs. The equivalent stiffnesses of the upper and lower assemblies are evaluated by the comparison of modal testing results and the finite element analysis. The stiffness for the oil film of the journal bearing is extracted by using Reynold's equation. In addition, the time responses for the vibration of the fuel pump are computed by using a commercial multi-body dynamics software, RecurDyn. Based on these results, some design suggestions are proposed to reduce the vibration of an automobile fuel pump.