• Proceedings of the KSME Conference
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• 2004.04a
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• pp.881-886
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• 2004

This paper presents the inverse dynamic analysis of the wheel loader manipulator based on the experimental data. A three dimensional rigid multi-body model of the wheel loader manipulator was built up. The inverse dynamic analysis for the typical operation mode was carried out by the ADAMS program. In order to verify the analysis result with the measured one, the hydraulic pressure and displacements of the cylinders were measured and the inverse dynamic analysis was carried out using experimental data. From the results of the analysis and measurement, it was concluded that the computational driving force showed good agreement with the measured one.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.2
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• pp.124-132
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• 2009

Experiments have been performed to investigate fluid-elastic instability of tube bundles, subjected to twophase cross flow. Fluid-elastic is the most important vibration excitation mechanism for heat exchanger tube bundles subjected to the cross flow. The test section consists of cantilevered flexible cylinder(s) and rigid cylinders of normal square array. From a practical design point of view, fluid-elastic instability may be expressed simply in terms of dimensionless flow velocity and dimensionless mass-damping parameter. For dynamic instability of cylinder rows, added mass, damping and the threshold flow velocity are evaluated. The Fluid-elastic instability coefficient is calculated and then compared to existing results given for tube bundles in normal square array.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2477-2482
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• 2008

Effect of computational domain size in simulating of periodic obstacle flow has been investigated for the flow past tube banks. Reynolds number, defined by freestream velocity (U) and cylinder diameter (d), was fixed as 200, and center-to-center distance (P) as 1.5d. In-line square array was considered. Drag coefficient, lift coefficient and Strouhal number were calculated depending on domain size. Circular cylinders were implemented on a Cartesian grid system by using an immersed boundary method. Boundary condition is periodic in both streamwise and lateral directions. Previous studies in literature often use a square domain with a side length of P, which contains only one cylinder. However, this study reveals that size is improper. Especially, RMS values of flow-induced forces are most sensitive to the domain size.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.8
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• pp.523-529
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• 2010

We investigate two-dimensional laminar flow around rectangular cylinders placed in a uniform stream. Numerical simulations are performed, using finite volume method, in the ranges of $50{\leq}Re{\leq}150$ and $0.1{\leq}W/H{\leq}1.0$, where Re and W/H are the Reynolds number and the width-to-height ratio, respectively. The immersed boundary method is used to handle the rectangular cylinder in a rectangular grid system. Comparisons with the previous results show good agreement in Strouhal number, drag and lift coefficient. The present study reports the detailed information of flow structure at different width-to-height ratios in the ranges of $50{\leq}Re{\leq}150$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.2
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• pp.157-166
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• 1999

Numerical calculations of turbulent natural convection in an enclosure of the 20 kYA oil-immersed transformer model are presented. The transformer is modelled as two concentric cylinders with different heights and diameters. The thermal boundary layers are well represented in the temperature distributions along the wall of the transformer model. The flow stratification between the hot and cold walls can not be seen in the transformer model. The turbulence eddy viscosity has its maximum at the center of the core and its maximum values at the top of the core are larger than those at the bottom of the core.

• Bulletin of the Society of Naval Architects of Korea
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• v.19 no.4
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• pp.47-52
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• 1982

The present paper gives numerical results of 2-D hydrodynamic forces on twin cylinders oscillating on a free surface in a deep water. The singularity distribution method is applied to determine a stream function. Based on the 2-D results the vertical motion responses of a catamaran model(ASR 5061) moving in regular head seas are estimated by using Ordinary Strip Method(O.S.M.). Numerical results show in general good agreements with Jones' theoretical and experimental results except those the resonance frequency.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1171-1175
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• 2017

Cryogenic helium gas is used as the pressurant for the oxidizer pressurization of DR(Damper Receiver) sphere in the PSD(Pogo Suppression Device) system and liquid oxygen is used as the oxidizer for the propellant in Korea Space Launch Vehicle-II. The helium gas is stored in pressurant cylinders inside the cryogenic liquid oxygen tank and liquid oxygen is stored in the oxidizer tank. In this study, the performance test of PSD liquid oxygen drain valve for KSLV-II was considered.

• International Journal of Naval Architecture and Ocean Engineering
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• v.4 no.3
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• pp.256-266
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• 2012

Cavitating flow simulation is of practical importance for many engineering systems, such as marine propellers, pump impellers, nozzles, torpedoes, etc. The present work has developed the base code to solve the cavitating flows past the axisymmetric bodies with several forebody shapes. The governing equation is the Navier-Stokes equation based on homogeneous mixture model. The momentum is in the mixture phase while the continuity equation is solved in liquid and vapor phase, separately. The solver employs an implicit preconditioning algorithm in curvilinear coordinates. The computations have been carried out for the cylinders with hemispherical, 1-caliber, and 0-caliber forebody and, then, compared with experiments and other numerical results. Fairly good agreements with experiments and numerical results have been achieved. It has been concluded that the present numerical code has successfully accounted for the cavitating flows past axisymmetric bodies. The present code has also shown the capability to simulate ventilated cavitation.

• Proceedings of the Membrane Society of Korea Conference
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• 1992.10a
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• pp.53-54
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• 1992

In this study characteristics of dynamic filters utilizing Taylor vortices were investigated both experimentally and theoretically. With fine silica slurry of 4.0 $\mu$m in average size experiments were conducted in Taylor vortices generated between the rotating inner cylinder consisting of microfiltration membrane of 1.2 $\mu$m in average pore size and the stationary outer cylinder. The diameter of the inner cylinder was 5.2 cm. Four outer cylinders having different diameters were manufactured and therefore four types of dynamic filters having the different ratio of the annular gap to the inner cylinder radius, i.e. 0.17, 0.33, 0.54, 0.65, were used as the experimental apparatus, as shown in Fig. 1.

• Journal of the Korea Concrete Institute
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• v.11 no.3
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• pp.161-170
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• 1999

The KLCC Petronas Tower 2, one of the world tallest twin reinforced concrete towers constructed in Kuala Lumpur, Malysia, was instrumented during construction for the measurement of vertical time-dependent deformation of columns and corewall. Field measurements were made by means of vibrating wire strain gauges at the corewall, tower and bustle perimeter columns at selected floor levels of the building. Parallel to this observation, laboratory tests were performed on concrete cylinders made in the field in order to obtain the variations of concrete compressive strengths, elastic moduli, strains of creep and shrinkage with time. Monitored vertical deformations are in a good agreement with the prediction based on actual construction sequence and concrete properties from laboratory tests, as well as the analytical results reflected in actual column compensation of the building.