• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.6
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• pp.1503-1509
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• 1994

An analysis method is suggested and experimentally studied in order to solve a vibration problem of a flexible structure while it is moving. In this method, substructure synthesis method, modal analysis method and Newmark's integral method were used. Total deformation of a structure was composed of quasistatic component and dynamic component. Rigid body modes were considered in calculation of dynamic component. Combining those two component, deformation behavior and a real structural model of a transfer feeder showed good agreements with computational results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.377-383
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• 1996

Recently, a new technique called Electronic Speckle Pattern Inteferometry(ESPI) has been developed to overcome the drawbacks of existing holography. This technique enable real-time interference fringes to be displayed directly on TV monitor without recourse to any form of photographic processing. This research was carried out for the purpose of applying the vibration analysis method employing Electronic Speckle Pattern Interference technique to the vibration analysis of uniform rectangular cantilever plate, The natural vibration frequencies found by ESPI were in fair agreement with theoretical eigen frequencies acquired using theoretical formula G. B. Warburton proposed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.12
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• pp.3020-3027
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• 1993

Curved beam element has received attention because of its own usefulness and its bearing on general curved elements like shells. In conventional curved beam elements stiffness matrix is overestimated and eigensolutions are poor. To avoid this phenomenon it is necessary to use a large number of elements and, as a result, the total number of degrees of freedom is increased. In this paper the two-noded, with three degrees of freedom at each node, in-plane curvature-based curbed beam element is employed in eigen-analysis of curved beam. It is shown that the curvature-based beam element is very efficient in vibration analysis and also that it is applicable to both thin and thick curved beams.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.679-685
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• 2003

Rotem has been using VAMPIRE for simulation and verification of the railway vehicle design. To improve the capability and accuracy of the analysis ability, ADAMS/Rail has been chosen as the next generation analysis tool. The dynamic performance of the railway vehicle, which is designed and manufactured by Rotem, is analyzed and simulated using ADAMS/Rail. The critical speed for linear and non-linear stability on tangent track, curving performance on various curved tractk, ride quality, derailment coefficient and the eigen values are calculated. In this paper, the results from ABAMS/Rail are compared with VAMPIRE's results.

• Advances in nano research
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• v.10 no.2
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• pp.165-174
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• 2021

This paper based on Sanders theory aims to investigate the vibration of SWCNTs considering the clamped-simply supported, clamped-free, clamped-clamped and simply supported-simply supported end conditions. After developing the governing equation of the objective system, the Rayleigh-Ritz technique is implemented for the purpose of obtaining the frequency equation in the eigen form. In addition, the applicability of this model for the analysis of vibration of CNTs is examined with the effect of length and ratio of height-to-radius. A detailed description of different types of SWCNTs with different indices is provided in the theoretical methodology. The effect of extended length is stimulated with increasing the radii and the model is effective because it also predicts the effect of thickness on vibration of SWCNTs. For different boundary conditions, the present results are verified with earlier literature.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.663-669
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• 2016

A terahertz asymmetric split-loop resonator (ASLR) was analyzed for use in high-sensitivity sensing applications. Its structural asymmetricity induces an asymmetric Fano resonance which has a high quality factor compared to the symmetric eigen-resonance. The variations of the resonant frequency, transmission coefficient, and quality factor of the ASLR in the eigen and Fano resonances are analyzed as a function of its structural asymmetricity. Also, the surface current densities on the ASLR in both resonances are calculated to analyze the main cause of the variations of its transmission characteristics. The surface current of the ASLR in the eigen resonance shows a dipole resonance, which increases the radiation loss and reduces the quality factor. On the other hand, the surface current of the ASLR in the Fano resonance shows a trapped or quadrupole mode which has a low radiation loss. Therefore, the ASLR operated in the Fano resonance has a high quality factor. Terahertz, high-performance filters and high sensitivity sensors can be developed based on our analysis results of the ASLR having a high quality factor. These high-performance devices based on terahertz metamaterials could increase the adoption of terahertz industrial applications.

• Journal of Korean Society of Steel Construction
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• v.24 no.3
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• pp.337-348
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• 2012

This study investigated the characteristics of bifurcation and the instability due to the initial imperfection of the space truss, which is sensitive to the initial conditions, and the calculated buckling load by the analysis of Eigen-values and the determinant of tangential stiffness. A two-free nodes model, a star dome, and a three-ring dome model were selected as case studies in order to examine the unstable phenomenon due to the sensitivity to Eigen mode, and the influence of the rise-span ratio and the load parameter on the buckling load were analyzed. The sensitivity to the imperfection of the two-free nodes model changed the critical path after reaching the limit point through the bifurcation mode, and the buckling load level was reduced by the increase in the amount of imperfection. The two sensitive buckling patterns for the model can be explained by investigating the displaced position of the free node, and the asymmetric Eigen mode was a major influence on the unstable behavior due to the initial imperfection. The sensitive mode was similar to the in-extensional mechanism basis of the simplified model. Since the rise-span ratio was higher, the effect of local buckling is more prominent than the global buckling in the star dome, and bifurcation on the equilibrium path occurring as the value of the load parameter was higher. Additionally, the buckling load levels of the star dome and the three-ring model were about 50-70% and 80-90% of the limit point, respectively.

• Journal of Broadcast Engineering
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• v.15 no.1
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• pp.122-132
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• 2010

AT-DMB system has been developed to increase data rate up to double of conventional T-DMB in the same bandwidth while maintaining backward compatibility. The AT-DMB system adopted hierarchical modulation which adds BPSK or QPSK signal as enhancement layer to existing DQPSK signal. The enhancement layer signal should be small enough to maintain backward compatibility and to minimize the coverage loss of conventional T-DMB service coverage. But this causes the enhancement layer signal of AT-DMB susceptible to fading effect in transmission channel. A turbo code which has improved error correction capability than convolutional code, is applied to the enhancement layer signal of the AT-DMB system for compensating channel distortion. However there is a need for other solutions for better reception of AT-DMB signal in receiver side without increasing transmitting power. In this paper, we propose adaptive array antenna system with Eigen-space beamforming algorithm which benefits beamforming gain along with diversity gain. We analyzed the reception performances of AT-DMB system in indoor and mobile environments when this new smart antenna system and algorithm is introduced. The computer simulation results are presented along with analysis comments.

• Journal of the Korea Convergence Society
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• v.11 no.7
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• pp.51-57
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• 2020

This study was conducted to examine the type of subjective perceptions and characteristics of the type toward the image of students enrolled in the Department of Radiology who experienced clinical training by applying Q Methodology which is aiming at the research of human subjectivity, and provide basic data for educational programs for the Department of Radiology to establish the image of a radiological technologist based on the result. This study conducted convenience sampling with 30 students of the Department of Radiology who experienced their first clinical training for 8 weeks as a P sample, forcing 33 Q samples to be distributed on the nine-point scale Q distribution chart. After that, this study processed collected data with principal factor analysis by QUANL program. Study results show that Eigen value was more than 1.0, which was divided into 2 types. Type 1 was "Patient-oriented" and type 2 was "Organization-oriented". These results can be helpful as a basic resources to understand Radiology Students who will choose a job by using different sense of value of their job.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.1
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• pp.20-29
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• 2010

The complicated flow characteristics of upper propeller wake influenced by hull wake are investigated in detail in the present study. A two-frame PIV (particle image velocimetry) technique was employed to visualize the upper propeller wake region. As the upper hull wake affects strongly propeller inflow, upper propeller wake shows much unstable vortical behavior, especially in the tip vortices. Velocity field measurements were conducted in a cavitation tunnel with a simulated hull wake. Generally, the hull wake generated by the hull of a marine ship may cause different loading distributions on the propeller blade in both upper and lower propeller planes. The unstable upper propeller wake caused by the ship's hull is expressed in terms of turbulent kinetic energy (TKE) and is identified by using the proper orthogonal decomposition (POD) method to characterize the coherent flow structure in it. Instabilities appeared in the eigen functions higher than the second one, giving unsteadiness to the downstream flow characteristics. The first eigen mode would be useful to find out the tip vortex positions immersed in the unstable downstream region.