• Journal of Korean Association for Spatial Structures
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• v.8 no.5
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• pp.67-74
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• 2008

Multi-layered stone masonry monuments, such as stone pagoda can be modeled as a multi-degrees of freedom system. The dynamic behavior of these structures are mainly influenced by contour condition of contacting surface of stones. In this case the mass of the system can be easily estimated, mean while the estimation of stiffness at junction is not simple. In this paper a method for estimating the spring constant at the contacting surface of stone in proposed. This paper describes a method of computational modelling technique for structural analysis of stone pagodas using measurement of natural frequency and eigenvalue analysis. For this purpose Five story stone pagoda in Cchongnimsa site was selected as a model.

• Journal of Korean Association for Spatial Structures
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• v.18 no.1
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• pp.45-53
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• 2018

Following the earthquake that shook the city of Gyeongju, Korea, in 2016, it became apparent that research on the safety of cultural heritages against the seismic hazards is necessary in Korea. Predictions of how historically significant stone pagodas would behave the earthquakes anticipated in near future, which are the subject of this study, is also required. In this study, the dynamic characteristics of 15 cultural heritage designated stone pagodas of Korea were investigated, including natural frequency and damping ratio, and the stiffness of the stone material and its contact area were determined using eigenvalue analysis by assuming the stone pagodas to be multi-degree-of-freedom structures. The results of this study enable the structural modeling of stone pagodas using a finite element analysis program and the method is expected to be useful in assessing the structural safety of stone pagodas against vertical loads as well as lateral forces, including earthquakes. Also, by identifying the dynamic characteristics of the structures, the results of this study can be utilized as a nondestructive testing method to determine the rigidity of cultural heritage structures and to identify inherent problems. The natural frequencies of the Korean stone pagodas were measured to be within 3.5~8.3Hz, excluding cases with distinct natural frequency results, and it was determined that the natural frequencies of the stone pagodas are influenced by various parameters including the height and joint stiffness of the structures.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.10a
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• pp.1-4
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• 2001

Dynamic analysis of laminated beams with a embedded damping layer under tension or compression axial load is investigated. Improved Layer-Wise Zig-Zag Beam Theory and Interdependent Kinematic Relation using the governing equations of motion are incorporated to model the laminated beams with a damping layer and a corresponding beam zig-zag finite element is developed. Flexural frequencies and modal loss actors under tension or compression axial load are calculated based on Complex Eigenvalue Method. The effect of the axial tension and compression load on the frequencies and loss factors is discussed.

• 한국전산유체공학회:학술대회논문집
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• 2001.05a
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• pp.127-133
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• 2001

In this paper, the preconditioned multistage time stepping methods which are popular multigrid smoothers is studied for the compressible flow calculations. Fourier analysis on the local time stepping and block-Jacobi preconditioned residual operators is performed using the linearized 2-D Navier-Stokes equations. It fumed out that block-Jacobi preconditioner has better performance in eigenvalue clustering. They are implemented in the 2-D compressible Euler and Wavier-Stokes calculations with multigrid methods to verify that the block-Jacobi preconditioned multistage time stepping shows better performance in convergence acceleration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.126-128
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• 2009

• Journal of applied mathematics & informatics
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• v.22 no.1_2
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• pp.273-283
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• 2006

We obtain an asymptotic behavior of the loss probability for the GI/PH/1/K queue as K tends to infinity when the traffic intensity p is strictly less than one. It is shown that the loss probability tends to 0 at a geometric rate and that the decay rate is related to the matrix generating function describing the service completions during an interarrival time.

• Journal of applied mathematics & informatics
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• v.22 no.1_2
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• pp.387-401
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• 2006

This paper deals with the problem of a ratio-dependent prey- predator model with combined harvesting. The existence of steady states and their stability are studied using eigenvalue analysis. Boundedness of the exploited system is examined. We derive conditions for persistence and global stability of the system. The possibility of existence of bionomic equilibria has been considered. The problem of optimal harvest policy is then solved by using Pontryagin's maximal principle.

• Journal of KSNVE
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• v.9 no.5
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• pp.928-935
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• 1999

Vertical pumps are widely used owing to the fact that they occupy small floor space. In this type of pumps, however, the vibrational problems are very important, since, in many cases, they have less stiffness in comparison with lateral pumps. This study presents a simple solution method for calculating the natural frequencies and modes of vertical pumps. In this study, a mode of a vertical pump was developed and the nondimensional parameters for the vibrational characteristics of it were determined. Added mass was calculated for the effects of water and the transfer matrix method was used.

• Journal of KSNVE
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• v.7 no.5
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• pp.773-780
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• 1997

Using Generalized Inverse Method presented by Udwadia and Kalaba in 1992, we can obtain equations to exactly describe the motion of constrained systems. When the differential equations are numerically integrated by any numerical integration scheme, the numerical results are generally found to veer away from satisfying constraint equations. Thus, this paper deals with the numerical integration of the differential equations describing constrained systems. Based on Baumgarte method, we propose numerical methods for reducing the errors in the satisfaction of the constraints.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.337-344
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• 2001

This paper is concerned with the change of joint rigidity in estimating the degree of semi-rigidity of connections and the buckling load in a single layer latticed dome. The estimations are based on information about the ratio for the rotational stiffness of the connection to the flexural stiffness of the member and the minimum eigenvalue of a structure for pinned, semi-rigid and completely rigid cases, respectively. Connection characteristics are reflected in the ratio control of joint rigidity for the DOFs to be related using the spring element by FEM.