• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.268-273
• /
• 2004

This study is conducted to clarify the effect of internal pressure on the deformation and collapse behaviors of wall thinned elbow under in-plane bending moment. Thus the nonlinear three-dmensional finite element analyses were performed to obtain the moment-rotation curve of elbow contatining various wall thinning defects located at intrados and extrados under in-plane bending (closing and opening modes) with internal pressure of $0{\sim}15MPa.$ From the results of analysis, the effect of internal of collapse moment of elbow on the global deformation behavior of wall thinned elbow was discussed, and the dependence of collapse moment of elbow on the magnitude of internal pressure was investigated under different loading mode, defect location, and defect shape.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.13 no.12
• /
• pp.1184-1195
• /
• 2001

Analysis of fluid flow in rectangular ducts has been conducted since it has a wide application. The purpose is to provide experimental data for the comparison with computational results. Velocity distributions inside a rectangular duct with $90^{\circ}$ mitered elbow are measured by 5W laser doppler velocity meter for Reynolds numbers of 4,049, 8,104, and 12,186. Flow rates obtained by the integration of measured velocity profile at three cross-sections, which are inlet, middle section after the elbow, and outlet, have errors less than 0.9% among them. Turbulent fluctuation components in two directions are found to have almost similar magnitude each other at a certain location due to the isotropic characteristic of turbulence.

• Journal of Advanced Marine Engineering and Technology
• /
• v.26 no.6
• /
• pp.670-678
• /
• 2002

Fluid flow in a rectangular duct with $90^{\circ}$ mitered elbow is measured by 5W laser doppler velocity meter. The fluid flow is also computed by commercial software of STAR-CD for comparison between measured and computed velocity profiles in the duct. Reynolds numbers for the comparison are 1,608 and 11,751 based on mean velocity and hydraulic diameter of the duct. First, the fluid flow of Reynolds number equal to 1,608 is predicted by assumptions of both laminar and turbulent models. But, even though the Reynolds number is less than 2,300~3,000, the computation by turbulent model is closed to the experimental data than that by laminar model. Second, the computation for Reynolds number of 11,751 by turbulent model also predicted the experimental data satisfactorily.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.4
• /
• pp.402-409
• /
• 2004

The purpose of this study is to investigate the effect of local wall thinning on the collapse of elbow subjected to internal pressure and bending moment. Thus, the nonlinear three-dimensional finite element analyses were performed to obtain the collapse moment of elbow containing various wall thinning defects located at intrados and extrados under two loading modes (closing and opening modes) with internal pressure. From the results of analysis, the effect of wall thinning defect on the global moment-rotation behavior of elbow was discussed, and the dependence of collapse moment of elbow on wall thinning depth, length, and circumferential angle was investigated under different loading mode and defect location.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.15 no.11
• /
• pp.910-917
• /
• 2003

Fluid flow in a rectangular duct for 90$^{\circ}$ bend elbow with the ratio of 1.5 between its curvature radius and width is measured by 5 W laser doppler velocity meter. The fluid flow is also computed by commercial software of STAR-CD for comparison between measured and computed velocity profiles in the duct. Reynolds numbers for the comparison are 11,643, 19,746 and 24,260. From the comparison, computation of principal velocity components in the duct predicts the experimental data somewhat satisfactorily even though those of minor velocity components and turbulent kinetic energy do not match with the experimental data quite well. K-factor for the bend elbow is computed to be average 0.086 while the equivalent ASHRAE data is 0.07.

• Proceedings of the Korean Institute of Industrial Safety Conference
• /
• 2004.04a
• /
• pp.387-392
• /
• 2004

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.594-607
• /
• 2004

• Journal of the Korean Applied Science and Technology
• /
• v.39 no.2
• /
• pp.335-339
• /
• 2022

The purpose of this research was to investigate the comparison of core muscle activities according to different performance in static Plank exercise. Ten "J" University's males(age, 23.20±0.65 years; height, 174.54±1.51 cm; body mass, 70.00±2.24 kg; and BMI, 22.94±0.51 kg/m²) completed this study as the subjects. Four type's static Plank motions were performed(full Plank, FP; elbow Plank, EP; side Plank, SP; reverse Plank, RP). For the EMG analysis, we measured the core muscle activities of right side on the rectus abdominis(RA), external oblique(EO), latissimus dorsi(LD), and erector spinae(ES). This research's results were as follows. LD and ES muscle activities were greatest during RP(p<.001). RA and EO muscle activities were greatest during EP(p<.001). Therefore, this results are anticipated to serve as basic data for static Plank performance applications in effective exercise programs.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.16 no.1
• /
• pp.1-10
• /
• 2020

This study proposed a simulated test method using ring specimen to evaluate the deformation and failure characteristics of pipe elbows under a large amplitude cyclic load. The validity of the test method was demonstrated by finite element (FE) analysis of pipe elbow and ring specimen under cyclic loads. The results showed that the proposed test method adequately simulates the distribution of circumferential strain at crown of pipe elbows where cracks occur under cyclic loads and presents the cyclic hardening behavior of pipe elbows. The parametric FE analysis showed that consistent simulated test results could be obtained when the test section of the ring specimen is longer than 1/2 of the inner diameter of the ring specimen and the radius of the inner loading jig is less than 1/4 of the inner diameter of the specimen.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.33 no.8
• /
• pp.826-831
• /
• 2009

The piping systems in nuclear power plant are composed of various typed pipes such as straight, elbow pipe, branch and reducer etc. The elbow is connected from straight pipe to another pipes in order to establish the complicated piping system. Elbow is one of very important components considering management of wall thinning degradation. It is however applied by various loads such as system pressure, earthquake, postulated break loading and many transient loads, which provoke simply the internal pressure, bending and torsional stress. In this study, firstly pipes in the secondary system of the nuclear power plant are classified as pipe size and type for selecting the investigating range. Next, a large number of finite element analysis considering the all typed dimensions of commercial pipe has been performed to find out the behavior of TES(twice elastic slop) plastic load of elbows, which is based on evaluation of the structural safety factor. Finally performance based structural safety factor was investigated comparing with maximum allowable load by construction code.