• Journal of Ocean Engineering and Technology
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• v.16 no.6
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• pp.18-24
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• 2002

The vibrational system in this study consists of a cantilever pipe conveying fluid, the moving mass upon it, and an attached tip mass. The equation of motion is derived by using the Lagrange equation. The influences of the velocity and the velocities of fluid flow in the pipe have been studied on the dynamic behavior of a cantilever pipe using a numerical method. While the moving mass moves upon the cantilever pipe, the velocity of fluid flow and the nozzle angle increase; as a result, the tip displacement of the cantilever pipe, conveying fluid, is decreased. After the moving mass passes over the cantilever pipe, the tip displacement of the pipe is influenced by the potential energy of the cantilever pipe and the deflection of the pipe; the effect is the result of the moving mass and gravity. As the velocity of fluid flow and nozzle angle increases, the natural frequency of he system is decreased at the second mode and third mode, but it is increased at the first mode. As the moving mass increases, the natural frequency of the system is decreased at all modes.

• Coupled systems mechanics
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• v.8 no.3
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• pp.199-218
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• 2019

This paper studies the forced vibration of the hydro-elastic system consisting of the anisotropic (orthotropic) plate, compressible viscous fluid and rigid wall within the scope of the exact equations and relations of elastodynamics for anisotropic bodies for describing of the plate motion, and with utilizing the linearized exact Navier-Stokes equations for describing of the fluid flow. For solution of the corresponding boundary value problem it is employed time-harmonic presentation of the sought values with respect to time and the Fourier transform with respect to the space coordinate on the coordinate axis directed along the plate length. Numerical results on the pressure acting on the interface plane between the plate and fluid are presented and discussed. The main aim in this discussion is focused on the study of the influence of the plate material anisotropy on the frequency response of the mentioned pressure. In particular, it is established that under fixed values of the shear modulus of the plate material a decrease in the values of the modulus of elasticity of the plate material in the direction of plate length causes to increase of the absolute values of the interface pressure. The numerical results are presented not only for the viscous fluid case but also for the inviscid fluid case.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.4
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• pp.1225-1232
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• 1996

In this paper the vibration and power flow analysis for the branched piping system conveying fluid are performed by wave approach. The uniform straight pipe element conveying fluid is formulated using the dynamic stiffness matrix by wave approach. The branched piping system conveying fluid can be easily formulated with considering of simple assumptions of displacements at the junction and continuity conditions of the pipe internal flow. The dynamic stiffness matrix for each uniform straight pipe element can be assembled by using the global assembly technique using in conventional finite element method. The computational method proposed in this paper can easily calculate the forced responses and power flow of the branched piping system conveying fluid regardless of finite element size and modal properties.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.4
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• pp.148-157
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• 1994

A multi-cylindrical hydraulic valve incorporating with an electro-rheological(ER) fluid is developed in this study. Field-dependent Bingham properties of the ER fluid are exploited to devise the valve system which features fast system response as well as simple mechanism. The fast response is accrued from almost instant response characteristics of the ER fluid itself, and the mechanism configuration is simplified since no nechanically moving parts are required. The material properties of the ER fluids to be utilized for modeling of the proposed valve system are firstly tested with a couette-type electroviscometer. The design and manufacturing processes are then undertaken on the basis of model parameters. The performance characteristics of the valve system are evaluated in terms of pressure variations with respect to the intensity of employed electric fields and flow rates.

• Proceedings of the Korea Contents Association Conference
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• 2006.11a
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• pp.264-268
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• 2006

This paper presents a fire and smoke animation system using stable fluid animation techniques. Stable and fast fluid simulation methods are developed in PC and console games, but fluid simulation and interactive fluid models still have many problems. We studied and implemented physics-based models for fluids like fire and smoke effects using mobile 3D system. The mobile platform of our system is WIPI, which are the standard mobile platform in Korea also we adopted NF3D API for our 3D programming API.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.131-137
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• 1999

Under magnetism , as the magneticfluid is being itself magnetized, increase the apparent viscosity because of its body force and has the magnetic characteristics in response ot magnetism, the magnetic fluid is getting attention in various field. The magnetic fluid has the fluidity, which is a special characteristics of fluid and the magneticism , which is a special one of solid. Using this characteristics, this study has been proceeded to show the basic data for developing of a viscous damper with magnetism fluid as hydraulic fluid. Experimental study shows that the application of magnetic field is effective reducing the resonance characteristics of the spring-mass system.

• Journal of computational fluids engineering
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• v.10 no.2
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• pp.69-81
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• 2005

A fluid transient analysis for the propellant flow in a monopropellant propulsion system is conducted by using the method of characteristics(MOC). It reviews algebraic simultaneous equations method and Cramer's rule method utilized to drive the compatible and characteristic equations to understand MOC extensively. The identification of fluid transient phenomena of propulsion system of Koreasat 1 is carried out through parametric studies. The valve response time is one of the dominant parameters governing the fluid transient phenomena. The results show that the shorter closing time induces the greater pressure response amplitude. And it shows that the installation of in-line orifice is effectively to limit the fluid transients in rapid valve response time and at high pressure. But it seems that the effect of orifice weakens at slow valve response time and at low pressures.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.10
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• pp.976-982
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• 2007

In this paper the vibration system is consisted of a rotating cantilever pipe conveying fluid and tip mass. The equation of motion is derived by using the Lagrange's equation. The system of pipe conveying fluid becomes unstable by flutter. Therefore, the influence of a rotating angular velocity, mass ratio, the velocity of fluid flow and tip mass on the stability of a cantilever pipe by the numerical method are studied. The critical flow velocity for flutter is proportional to the angular velocity and tip mass of the cantilever pipe. Also, the critical flow velocity and stability maps of the pipe system are obtained by changing the mass ratios.

• Journal of the Korean Solar Energy Society
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• v.25 no.4
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• pp.37-44
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• 2005

An experimental study was conducted to analyze performance of a heating system with variation of control logic of the system. The system uses a solar as heat source and composed with heat pump that uses R-22 as working fluid. The difference between the developed system and the commercially available heating system is working fluid. The solar assisted heating system which was widely distributed in the market uses water as a working fluid. It could be freezing in case of the temperature drops down under freezing point. The anti-freezing fluids such as methyl-alcohol or ethylene-glycol are mixed with the water to protect the freezing phenomena. However, the system developed in this study uses a refrigerant as a working fluid. It makes the system to run under zero degree temperature conditions. Another difference of the developed system compare with commercial available one is auxiliary heating method. The developed system has removed an auxiliary electric heater that has been used in conventional solar assisted heating system. Instead of the auxiliary electric heater, an air source heat exchanger which generally used as an evaporator of a heat pump was adapted as a backup heating device of the developed system. As results, an efficiency of the developed system is higher than a solar assisted heat pump with auxiliary electric heater. The merit of the developed system is on the performance increment when the system operates at a lower solar energy climate conditions. In case of the developed system operates at a normal condition, COP of the solar collector driven heat pump is higher than the air source heat exchanger driven heat pump's.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.8
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• pp.764-772
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• 2009

In this study, fluid/structure coupled analyses have been conducted for 3-D stator and rotor configuration. Advanced computational analysis system based on computational fluid dynamics(CFD) and computational structural dynamics(CSD) has been developed in order to investigate fluid/structure responses of general stator-rotor configurations. To solve the fluid/structure coupled problems, fluid domains are modeled using the structural grid system with dynamic moving and local deforming techniques. Reynolds-averaged Navier-Stokes equations with Spalart-Allmaras(S-A) and SST ${\kappa}-{\omega}$ turbulence models are solved for unsteady flow problems. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of the 3-D turbine blades for fluid-structure interaction(FSI) problems. Detailed fluid/structure analysis responses for stator-rotor interaction flow conditions are presented to show the physical performance and flow characteristics.