• 대한기계학회논문집
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• 제19권5호
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• pp.1291-1299
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• 1995

In confined coaxial jets, the flow-mixing characteristics depend on the initial conditions at the nozzle outlet such as velocity ratio and nozzle radius ratio. In this study, nozzle ratio(inner/outer) was 0.3. Longitudinal axial velocity, turbulent intensity and Reynolds shear stress were measured by CTA. Measurements were made from the duct inlet to the region where similarity solution could exist. This study investigated flow charicteristics according to the variation of similitude parameter which was derived from the theory of Craya-Cutet. The range of similarity region depends on the variation of the similitude patameter. The form factor obtained from the axial velocity profile in the similarity region was constant. The higher the similitude parameter, the wider the spread rate of the jets. Due to this fact, the similarity conditions developed more quickly and the region where the similarity holds became narrow. Present experimental data confirmed the validity of Craya-Curtet theory.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.371-379
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• 2000

A noise prediction method of axial flow fan is developed by incorporating through-flow method and vortex shedding noise model. Fan noise is assumed to be generated due to the pressure fluctuation induced by wake vortices of fan blades and radiate as diploe distribution. The wake vortices are analyzed by combining Karman vortex street model and through-flow analysis results, and the vortex-induced fluctuating pressure on blade surface is calculated by thin airfoil theory. The predicted sound pressure levels and directivity patterns of fan noise by the present method are favorably compared with fan noise test data. Furthermore, the present method is shown to be very useful for predicting the aero-acoustic performance map of the fan operated at off-design point.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2001년도 춘계학술대회 발표논문집
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• pp.103-107
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• 2001

This study is simulation about buckling behavior under axial compression which is cylindrical panel laminated USN125 and USN150 made by various winding angle. And also this study compare with linear and nonlinear FDEM theory, and FEM theory. To solve the objective function and the design variables, this study use the linear and nonlinear buckling theories or FDEM and nonlinear search optimum design method of ADS for minimum weight design on which stiffened laminated composite cylindrical panel with stiffener that R-type section.

• KIEAE Journal
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• 제7권6호
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• pp.119-126
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• 2007

In the field of composite structures, the use of carbon tube for the confinement of concrete has been arisen since 1990's. However, experimental and analytical studies were limited to those of reinforced concrete and concrete filled steel tube. The carbon tube provides excellent confinement capabilities for concrete cores, enhancing compressive strength and ductility of concrete significantly. The carbon tube has high tensile strength, light weight, corrosion immunity and high fatigue strength properties. Since carbon fiber is an anisotropic material, carbon tube could be optimized by adjusting the fiber orientation, thickness and the number of different layers. In this study, both experimental and analytical studies of axial and lateral behavior of full-scale CFCT (Concrete Filled Carbon Tube) columns subjected to monotonic axial load were carried out using Drucker-Prager theory. And, based on comparison results between experiment results and analytical results, k factor estimation was proposed for effective analysis.

• 한국정밀공학회지
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• 제27권6호
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• pp.90-97
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• 2010

In order to understand the biomaterial like the blood vessel of artery, there is a need to quantify the biomechanical behavior of the vessel. Using computer-controlled experimental system, the experiment can acquire data such as inner pressure, axial load, diameter and axial gauge length without contacting the specimen. Rubber-liked material which is similar to passive artery was selected as pseudo-biomaterial. Deformations are measured for pressure-diameter curves. The data were collected and stored online to be used in the feedback control of experimental protocols. Finally, the illustrative data obtained from the experimental system were presented and the system shows that strain invariants are controlled to understand the nonlinear elastic behavior of biomaterial which is involved with strain energy function.

• Steel and Composite Structures
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• 제31권3호
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• pp.243-259
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• 2019

This study deals with the nonlinear static analysis of functionally graded carbon nanotubes reinforced composite (FG-CNTRC) truncated conical shells subjected to axial load based on the classical shell theory. Detailed studies for both nonlinear buckling and post-buckling behavior of truncated conical shells. The truncated conical shells are reinforced by single-walled carbon nanotubes which alter according to linear functions of the shell thickness. The nonlinear equations are solved by both the Airy stress function and Galerkin method based on the classical shell theory. In numerical results, the influences of various types of distribution and volume fractions of carbon nanotubes, geometrical parameters, elastic foundations on the nonlinear buckling and post-buckling behavior of FG-CNTRC truncated conical shells are presented. The proposed results are validated by comparing with other authors.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2650-2652
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• 2011

The fiber reinforced composite materials have many advantages due to their high strength-to-density ratios. Thus they have been widely used in many industrial applications. As the wave propagation are closely related to dynamic analysis of structures, it is very important to predict them. This paper presents a wave propagation in the axially loaded axial-bending-shear coupled composite laminated beams which are represented by the Timoshenko beam models based on the first-order shear deformation theory.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.666-671
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• 1993

Fatigue life prediction under multi-axial variable load were performed for Aluminium 7075-T651 alloy using SAE Notched specimen & Torque tube shaft component specimen. When variable multiaxial load is applied to material, maximum damaged plane(critical plane) change. To clarify the situation, experiment is performed on two different changing load path. For multiaxial fatigue life prediction, miner rule is expanded to critical plane theory. Shear based parameter and Elliptical parameter give better correlation. This suggests that miner rule can be applicable on multi-axial variable load.

• Advances in nano research
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• 제10권5호
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• pp.493-507
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• 2021

This article focused on studying the buckling behavior of two-dimensional functionally graded (2D-FG) nanosize tubes, including porosity based on first shear deformation and higher-order theory of tube. The nano-scale tube is simulated based on the nonlocal gradient strain theory, and the general equations and boundary conditions are derived using Hamilton's principle for the Zhang-Fu's tube model (as higher-order theory) and Timoshenko beam theory. Finally, the derived equations are solved using a numerical method for both simply-supported and clamped boundary conditions. The parametric study is performed to study the effects of different parameters such as axial and radial FG power indexes, porosity parameter, nonlocal gradient strain parameters on the buckling behavior of di-dimensional functionally graded porous tube.

• Journal of Advanced Marine Engineering and Technology
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• 제32권6호
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• pp.827-833
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• 2008

In this study, mathematical expressions based upon the conventional BEMT(blade element momentum theory) was applied to basic 100kW wind turbine blade configuration design. Power coefficient and related flow parameters, such as Prandtl's tip loss coefficient, tangential and axial flow induction factors of the wind turbine were analyzed systematically. X-FOIL was used to acquire lift and drag coefficients of the 2-D airfoils and Viterna-Corrigan formula was used o interpolate he aerodynamic characteristics in post-stall region. Also, aerodynamic characteristics, measured in a wind tunnel to calculate he power coefficient was applied. The comparative results such as axial and tangential flow factors, power coefficients were presented in this study. Power coefficient, calculated by in-house code was compared with the GH-Bladed result. The difference of the aerodynamic characteristics caused the difference of the performance characteristics as variation as TSR.