• International Journal of Ocean System Engineering
• /
• v.1 no.2
• /
• pp.76-88
• /
• 2011

The present study deals with the hydroelastic vibration analysis of structures in contact with fluid via coupled fluid-structure interaction (FSI) embedded with a finite element method (FEM) such that a structure displacement formulation is coupled with a fluid pressure-displacement formulation. For the preliminary study and validation of FEM based coupled FSI analysis, hydroelastic vibration characteristics of a rectangular plate in contact with fluid are first compared with the elastic vibration in terms of boundary condition and mode frequency. Numerical results from coupled FSI analysis have been shown to be rational and accurate, compared to energy method based theoretical solutions and experimental results. The effect of free surface on the vibration mode is numerically studied by changing the submerged depth of a rectangular plate. As a practical application, the hull structural vibration of 4,000 twenty-foot equivalent units (TEU) container ship is considered. Hydroelastic results of the ship hull structure are compared with those obtained from the elastic condition.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.932-937
• /
• 2008

The pulsation of a reciprocating type hydrogen compressor is occurred from the mechanism and this pulsation makes much noise and vibration. To reduce this pulsation, snubber is usually installed on that. To maintain the efficiency in the reciprocating type hydrogen compressor, the pulsation and vibration should be reduced. so it is necessary to research about the characteristic of pulsation and vibration. Therefore in this paper, the vibration characteristic of the snubber is analyzed in the base of optimized modeling condition through the flowing analysis of existing snubber. The prototype of reciprocating type hydrogen compressor is analyzed with numerical analysis. And making sure the present condition of hydrogen compressor through measurement of vibration and noise, and then it is established that the vibration characteristic data base on numerical analysis which will be develope.

• Korean Chemical Engineering Research
• /
• v.59 no.1
• /
• pp.138-151
• /
• 2021

The effect of a reactant ratio on the growth of a buoyancy-driven instability in an irreversible A+B→C reaction system is analyzed theoretically and numerically. Taking a non-stoichiometric reactant ratio into account, new linear stability equations are derived without the quasi-steady state assumption (QSSA) and solved analytically. It is found that the main parameters to explain the present system are the Damköhler number, the dimensionless density difference of chemical species and the ratio of reactants. The present initial grow rate analysis without QSSA shows that the system is initially unconditionally stable regardless of the parameter values; however, the previous initial growth rate analysis based on the QSSA predicted the system is unstable if the system is physically unstable. For time evolving cases, the present growth rates obtained from the spectral analysis and pseudo-spectral method support each other, but quite differently from that obtained under the conventional QSSA. Adopting the result of the linear stability analysis as an initial condition, fully nonlinear direct numerical simulations are conducted. Both the linear analysis and the nonlinear simulation show that the reactant ratio plays an important role in the onset and the growth of the instability motion.

• Archives of design research
• /
• v.15 no.4
• /
• pp.215-222
• /
• 2002

Through this research, I intend to examine the possibility of utilizing the plaza in front of a station as a citizen plaza within the city, which citizen can use actively. Until now, the plaza in front of a station is utilized as a traffic square. As part of this examination, I'll consider a plaza generally and analyse the present condition of the plaza in front of a station as well as physical environment. Then I will grasp the present condition and problems. Through this, 1 intend to extract basic materials enough to find the possibility of the plaza in front of a station as a citizen resting place.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.40 no.1
• /
• pp.129-138
• /
• 2015

The problems associated with the excessive compensation of the public organizations in Korea have been presented not only by the press but also by the academic societies, including the management evaluation team of the public organizations, both in Korea and abroad. To analyze whether the compensation is excessive necessitates the empirical study on the present condition of the compensation system of the public organizations. Therefore, the purpose of this paper is to suggest the issues and the future directions of the compensation in the public organizations. The findings from the analysis of the data collected in this research include the expansion of the difference in compensation, the reinforcement of the job and performance-based compensation, the systematization of the model on the base compensation, and the differentiation of the compensation increase based on productivity.

• Proceedings of the KSR Conference
• /
• 2004.06a
• /
• pp.557-561
• /
• 2004

In internationalization age, growth plan of a railway have to research with the opening of a train express and connection with a transcontinental railway. Especially, in the opening of a train express, the North Korea is located in an important place. So the North Korea must research for growth of railway of the South Korea. This study make an investigation the present condition of railway of the North Korea into a report, paper, article etc.. And then, it make a comparative study with a case study of Germany. Then, a policy object, have to be stand at the head in the opening of a train express, exhibited.

• 유체기계공업학회:학술대회논문집
• /
• 2006.08a
• /
• pp.345-348
• /
• 2006

In sheet metal forming process using press and draw die some defect can be made because of the high pressure of air pocket between draw die and the product. The purpose of this study is to develop a program to decide an optimal combination of air vent hole size and number to prevent those defect on product. The air inside air pocket is considered as ideal gas and the compression and expansion is assumed as isentropic process. The mass flow is computed in two flow condition: unchocked and chocked condition. The present computation obtains required cross-sectional area of air vent hole for not exceeding the user specified pressure such as the pressure for yielding strength of the product or the pressure for unchocked flow. To validate the program the present results are compared with the results of other researchers and commercial CFD code.

• 한국전산유체공학회:학술대회논문집
• /
• 2010.05a
• /
• pp.99-102
• /
• 2010

In the present study, a three-dimensional numerical simulation was performed in a paint drying system of vehicle assembly line. In the drying system hot air and cool air are blown in turn from the nozzles to dry the trim of vehicle. Inlet boundary condition using user subroutine code is adopted to consider the moving motion of the vehicle. The present paper aims to improve the performance of the drying system. The transient distribution of temperature and velocity at the surface of the vehicle were predicted numerically. From these results, optimal operating condition of the drying system are to be suggested.

• Journal of Power System Engineering
• /
• v.15 no.6
• /
• pp.47-52
• /
• 2011

In this study, an accurate 2-noded hybrid-mixed element for continuous fiber-reinforced laminated beams is newly proposed. The present element including the effect of shear deformation is based on Hellinger-Reissner variational principle, and introduces additional consistent node less degrees for displacement field interpolation in order to enhance the numerical performance. The micromechanical and lamination theory are employed in the finite element description to consider the effects of the laminate stacking sequences, material orthotropy, and fiber volume fraction, etc. The element stiffness matrix can be explicitly derived through the stationary condition and static condensation using Mathematica program. Several numerical examples confirm the accuracy of the present hybrid-mixed element and also show in detail the effects of the continuous fiber volume fraction, stacking sequences and boundary condition on the bending behavior of laminated beams.

• Journal of ILASS-Korea
• /
• v.14 no.4
• /
• pp.163-170
• /
• 2009

The present study has numerically investigates the vaporization, auto-ignition and combustion processes in the high-pressure and high-temperature conditions encountered in the diesel engine. In the present study, in order to understand the overall spray combustion characteristics of DME fuel as well as to identify the distinctive differences of DME combustion processes compared to conventional hydrocarbon liquid fuels, the sequence of the comparative analysis has been systematically made for DME and n-Heptane liquid fuels. Computations for DME fuel are made for two cases including constant fuel mass flow rate condition and fixed heat release rate. Based on numerical results, the discussions are made for the detailed combustion processes of DME and n-Heptane spray.