• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2003.10a
• /
• pp.452-461
• /
• 2003

The effect of initial combined load on the lateral free vibration of arches is investigated. For the analysis, P-M interaction own for the arches are obtained. The arches are circular arches which have constant cross-section and simply supported. Also, the arches are subjected both radial uniform distributed load which results in an axial compression on the cross-section and end moments that cause uniform bending action at the same time. All analysis are performed by finite element method based on Kang and Yoo's curved beam theory.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 1998.10a
• /
• pp.173-179
• /
• 1998

The piping system of a power plant suffers not only thermal expansion according to the temperature variation, but also many kinds of load: steady state vibrations due to the equipment operation or fluid flow, and transient vibrations due to the earthquake or explosion, etc. The snubbers are usually installed on the piping system to allow thermal expansion, and to reduce dynamic responses. Most snubbers are kinds of hydraulic and mechanical type, which can be degraded by leakage and abrasion, and required much cost for maintenance and replacement. Recently the wire rope type snubbers are developed and applied to the power plant, and proved as effective to reduce piping system vibration. Wire rope type snubber uses the bending rigidity and energy dissipation properties of ropes. This paper presents the procedure of design, and the method to apply hysteresis curve to the dynamic response analysis. Experiments were also conducted to confirm design results.

• Journal of Advanced Marine Engineering and Technology
• /
• v.14 no.3
• /
• pp.34-41
• /
• 1990

Mode Synthesis Method is applied to analyize the vibration characteristics of the press machine sold at present. Vibration analysis of the machine has not been done thoroughly as far, because of its complicated structure and much bigger unlinearity of its vibration characteristics. The press was disassembled by parts, and it was experimented by the exciting techniques and curve fitting methods, and analyzed by the Mode Synthesis Method. The 2 results were showed good agreements at each part. We confirming it, the machine was assembled, and experimented and analyzed by the same method. Also good agreements between 2 methods were obtained. In addition, impact responses of the actual moving press were agreed with the analyzed values by the Mode Synthesis Method. And we found that the first bending mode of the slide was ruling the vibration characteristics of the press.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2005.05a
• /
• pp.191-196
• /
• 2005

The effects of shot peening on the fatigue strength of SK-5M steel is investigated by experiment. The shot peening process is investigated optimum peening condition by changing impeller speed and exposure time. Bending fatigue test is accomplished to investigate the effect of optimum peening condition on the fatigue characteristics. As exposure time is increased, fatigue life in high stress is increased in early stage, become the maximum from 60 to 100 seconds, and then is decreased. Observing fracture surface through SEM after fatigue test, we can see clear configuration of cracks and peening layer.

• KCI Concrete Journal
• /
• v.12 no.1
• /
• pp.35-46
• /
• 2000

A research program was initiated at the University of Colorado at Boulder to develop computational models that can be used for seismic risk assessments. To assess the overall performance of bridge structures including the nonlinear effects of bridge piers, the research focused on two levels of capabilities, i.e. global and local pier levels. A 3-D concrete model was used to evaluate the behavior of individual piers under combined axial, bending, and shear loadings using 3-D finite element analysis. Whereby the response curve reached the peak strength of the R/C column under the constant axial and monotonically increasing lateral loads. Experimental results on reinforced concrete bridge piers, which were obtained at the University of California at San Diego were used to validate the seismic performance of bridge piers at the two levels, globa1 and local.

• The KSFM Journal of Fluid Machinery
• /
• v.16 no.4
• /
• pp.15-21
• /
• 2013

This study aims to estimate the fatigue resistance of small wind composite blade using the fatigue life estimation formula in the GL guideline. For this, firstly, we estimated a turbine blade's bending moment spectrum by using wind profile wind profile and BEMT. And fatigue tests were performed to obtain the S-N curve of composite materials used in blade. In addition, a finite element analysis was used to identify fatigue critical locations and fatigue stress spectrum. And the fatigue resistance of composite blade were evaluated using the rainflow cycle counting, and Goodman diagram and the fatigue life estimation formula in the GL guideline.

• Proceedings of the KIEE Conference
• /
• 1999.07g
• /
• pp.3286-3288
• /
• 1999

The electrostatically actuated test structure was presented to measure the micro mechanical characteristics of micromaterials as thin films forming the microactuators. The test structure was fabricated by the surface micromachining processes and driven by the electrostatic force, In order to measure the fracture toughness, the sharp notch in the test structure was introduced by the etching process. On the basis of the beam bending theory, the elastic modulus was measured by using the microcantilevr beam and the mechanical displacement, curvature and deflection curve under the electrostatic force was evaluated by using the electrostatic structure.

• Transactions of Materials Processing
• /
• v.10 no.1
• /
• pp.3-14
• /
• 2001

Hydroforming is the technology using hydraulic pressure and forming sheet or tube metals to desired shape in a die cavity. lt can be characterized as tube hydroforming and sheet hydroforming depending on the shape of used blank. Due to its prcess-related benefits, this production technology has been remarkably noticed for great potential for feasible applications and recently gained great attraction from many industrials including automotive and non-automotive. This Paper analyzed the tube and the welded blank hydroforming process and compared formability of the processes for automotive engine mount bracket. The mathematical analysis was performed by using the dynamic explicit finite element code, PAM-STAMP. In tube hydroforming, bending, springback, and forming analysis were carried out and the effect of mandrel and axial feeding were examined. In welded blank hydroforming, pressure curve history is determined and the results of forming analysis were evaluated by the comparison of experimental results in the aspects of deformed shape and thickness distribution.

• Journal of Ocean Engineering and Technology
• /
• v.22 no.2
• /
• pp.58-64
• /
• 2008

Large-scale tests of welded tubular K-joint sunder balanced in-plane bending braces were carried out to observe the fatigue behavior of the API 2W Gr.60 steel plate produced by POSCO. Toe grinding and weld profiling were used to improve the fatigue life of a tubular K-joint. The effects of the steel grade and chord wall thickness on the fatigue life were also investigated. The present results were compared with the UK DEn design curve.

• Bulletin of the Korean Chemical Society
• /
• v.17 no.4
• /
• pp.358-362
• /
• 1996

The ionic strength dependent binding mode of 9-aminoacridine (9AA), a well-known DNA intercalator, to DNA is studied by flow linear dichroism, circular dichroism, fluorescence techniques and equilibrium dialysis. The DNA-bound 9AA exhibits spectral properties corresponding to the intercalative binding mode disregarding the salt concentrations; the angle between the long-axis transition moment of the 9AA molecule and DNA helix axis is calculated to be about 65°, indicating a significant deviation from the classical intercalation. At low salt concentrations, however, upwards bending curve in Stern-Volmer plot is observed (where 9AA is a fluorophore and DNA a quencher), indicating the coexistence of both static and dynamic quenching mechanisms or the existence of an additional binding site.