• Journal of KSNVE
• /
• v.3 no.3
• /
• pp.259-269
• /
• 1993

For efficient use of composite materials in engineering applications the dynamic behavior, that is, natural frequencies, nodal patterns should be informed. This study presents the experimental and FEM results for the free vibration of cantilevered, symmetrically and antisymmetrically laminated composite triangular plates. The natural frequencies and nodal patterns of a number of CFRP, GFRP, composite-Aluminum and CFRP-GFRP hybrid composite plates are experimentally obtained. A method for the determination of the Young's modulus and test procedures are described. The natural frequencies are determined for a wide range of parameters: e.g., composite material constants, fiber angles and stacking sequences. Natural frequency and nondimensional frequency parameter results are compared with the finite element analysis and existing literatures. Agreement between experimental and calculated frequencies is excellent.

• Tribology and Lubricants
• /
• v.28 no.5
• /
• pp.218-232
• /
• 2012

In a spool valve analysis, the Reynolds equation is commonly used to investigate the lubrication characteristics. However, the validity of the Reynolds equation is questionable in a spool valve analysis because cavitation often occurs in the groove and the depth of the groove is much higher than the clearance in most cases. Therefore, the validity of the Reynolds equation in a spool valve analysis is investigated by comparing the results obtained from the Reynolds equation and the Navier-Stokes equation. Dimensionless parameters are determined from a nondimensional form of the governing equations. The differences between the lateral force, friction force, and volume flow rate (leakage) obtained by the Reynolds equation and those obtained by the Navier-Stokes equation are discussed. It is shown that there is little difference (less than 10%), except in the case of a spool valve with many grooves where no cavitation occurs in the grooves. In most cases, the Reynolds equation is effective for a spool valve analysis under a no cavitation condition.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.19 no.2
• /
• pp.1-11
• /
• 1982

Ship bottom structure is idealized by an equivalent orthotropic plate upon which uniform lateral, uni-axial and bi-axial loads act. Solutions in the form of series representing deflections and moments at the center are obtained in case of simply supported and fixed boundary conditions. Variables in the solutions are reduced and grouped in nondimensional parameters. Stresses in the members of actual plate-stiffener combination are calculated corresponding to moments obtained above. In this paper design curves of deflections and moments for two different sets of boundary conditions are given, and they are compared with Schade's design curves and Mansour's design curves. Some examples for application are given and compared with the results obtained by FEM(SAPIV) in appendix.

• Journal of the Korean Society of Combustion
• /
• v.12 no.1
• /
• pp.1-10
• /
• 2007

Analytical investigation of acoustic wave scattering from turbulent premixed flames was conducted to evaluate the acoustic energy amplification/damping. Such acoustic energy change is attributed to the acoustic velocity jump due to flame's heat release. Small perturbation method up to second order and stochastic analysis were utilized to formulate net acoustic energy and the energy transfer from coherent to incoherent energy. Randomly wrinkled flame surface is responsible for the energy transfer from coherent to incoherent field. Nondimensional parameters that govern net acoustic energy were determined: rms height and correlation length of flame front, incident wave frequency, incidence angle, and temperature ratio. The dependence of net acoustic energy upon these parameters is illustrated by numerical simulations in case of Gaussian statistics of flame front. Total net energy was amplified and the major factors that affect such energy amplification are incidence angle and temperature ratio. Coherent (incoherent) energy is damped (amplified) with rms height and correlation length of flame front.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.10 no.1
• /
• pp.1-7
• /
• 1990

A method is developed for solving the elastica of cantilever beam subjected to a tip point load and uniform load. The Bernoulli-Euler differential equation of deflected beam is used. The Runge-Kutta method and the Regula Falsi method are used to perform the integration of the differential eqution and to determine the horizontal deflection, respectively. The horizontal and vertical deflections of the free end, and the free-end rotations are calculated for a range of parameters representing variations in tip point load and uniform load. All results are presented in nondimensional forms. And some typical elastic are also presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.05a
• /
• pp.942-947
• /
• 2004

The differential equations governing free, in-plane vibrations of stepped non-circuiar arches are derived as nondimensional forms including the effects of rotatory inertia, shear deformation and axial deformation. The governing equations are solved numerically to obtain frequencies and mode shapes. The lowest four natural frequencies and mode shapes are calculated for the stepped parabolic arches with hinged-hinged, hinged-clamped, and clamped-clamped end constraints. A wide range of arch rise to span length ratios, slenderness ratios, section ratios, and discontinuous sector ratios are considered. The effect of rotatory inertia and shear deformation on natural frequencies is reported. Typical mode shapes of vibrating arches are also presented.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.7 no.8
• /
• pp.132-142
• /
• 1999

In this paper, a new formula for primary and secondary thrust of metal belt CVT is proposed considering variation of band tension, block compression and active arc for each of the primary and secondary pulleys. For the secondary thrust, effective friction coefficient is introduced considering the effect of flange deflection. Nondimensional primary and secondary thrust of the metal belt CVT by the new formula agree well with the experimental results except for low torque range, $0\;<\;{\lambda}\;<\;0.2$ at speed ration i = 1.0. The new formula can be used in design of the primary and secondary thrusts control system for the metal belt CVT.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.16 no.2
• /
• pp.167-174
• /
• 2004

A sorption cool pad brings cooling effect without any pre-cooling, nor any external energy supply. It uses evaporative cooling effect stimulated by the desiccative sorption. In this paper, heat and mass transfer in the sorption cool pad are investigated theoretically. The evaporative cooling process caused by the desiccant is modeled and analyzed considering the sorption characteristics of the desiccant. Two nondimensional parameters are found to dominate the cooling process： one is related to the psychrometric characteristics and the other is to the sorption capacity of the desiccant. The former decides the time to reach the lowest temperature and the later controls the time duration of the cooling effect being sustained.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.11 no.2
• /
• pp.27-37
• /
• 1991

The behavior of a negative buoyant flow flowing into a small reservoir is analysed by experiments and dimensional analysis. The nondimensional plunge point, head velocity, head travel distance and the dilution of density current are dependent on the inflow densimetric Froude number, Fre. The thickness of density current, flow pattern and density difference are different from two cases as follows; before the front of head arrive at the downstream end and after. Before the arrival, the thickness of density current is dependent on Fre and after the arrival, time and Fre. It was found that they can be expressed as power laws.

• The KSFM Journal of Fluid Machinery
• /
• v.12 no.2
• /
• pp.17-23
• /
• 2009

The program using $C/C^{++}$ which could calculate 3-D velocities from data of the flowfield obtained by a slant hot-wire has been developed. The characteristic of the exit flowfield of a circular nozzle with a curved surface was investigated. From the result, the inward-flow was verified at adjacent layers near the boundary of the exit flowfield of a circular nozzle in Id and outward-flow was sensed gradually from down-flow of Id. Similarity of the nondimensional velocity profile properlly could be obtained except near Id and the virtual origin reasonably could be obtained.