• The Journal of the Acoustical Society of Korea
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• v.29 no.1
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• pp.1-9
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• 2010

The mutual radiation impedance was calculated using the spatial convolution in the cylindrical structure. The Cartesian coordinate was transformed into the cylindrical coordinate using the spatial convolution for the cylindrical array structure. This method cannot consider the cylindrical baffle, but can reduce the computation time. The error for not considering the cylindrical baffle was analyzed by the comparison of the spatial convolution method with the quadruple integration method in the cylindrical structure. The mutual radiation resistance in the cylindrical structure was compared with the one in the planar baffle. Based on two kinds of the comparison, we presented the error of the suggesting method in this paper, confirming that the spatial convolution method could be applied to compute the mutual radiation impedance in the cylindrical structure at certain conditions.

• International journal of steel structures
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• v.18 no.4
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• pp.1167-1176
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• 2018

Steel cylindrical tanks are widely used for the storage of hazardous substances of which leakage must be prevented under any circumstances. However, the dynamic response of the steel cylindrical liquid storage tank depends sensitively on the fluid-structure interaction and the vibration of the tank structure and necessitates clarification for the safety of the tank structure. This paper presents the results of shaking table tests performed to examine the dynamic behavior of a scaled cylindrical steel tank model considering the presence or not of fixed roof and added mass at the top of the tank for various fluid levels. The test results confirm the occurrence of both beam-type and oval-type vibration modes and show that the larger content of liquid inside the container amplified the acceleration along the height of the cylindrical tank. The oval-type vibration modes are seen to be more dominant in case of large water-to-structure mass ratio.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.2
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• pp.196-203
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• 2015

In order to apply cylindrical periodic array to phased array antenna or frequency selective surface, efficient electromagnetic analysis is required. Finite periodic array is applied in real situation. But, generally, assumed that periodic structure is arranged infinitely, approximate electromagnetic characteristics can be obtained efficiently. But, difference of characteristics between real structure and approximate structure occurs because finite periodic array is approximated to infinite periodic array. Therefore, comparison and analysis of cylindrical infinite array and finite array are required. In this paper, cylindrical infinite periodic array are analyzed using cylindrical Floquet harmonics. Also, cylindrical finite periodic array is analyzed using method of moments (MoM) with thin wire approximation because periodic structures which are composed of strip with narrow width are analyzed. Transmission characteristics and surface currents of infinite and finite periodic structures are compared.

• Coupled systems mechanics
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• v.7 no.3
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• pp.297-319
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• 2018

In this paper, the vibro-acoustic behaviors of vibrational cylindrical shells are investigated by using structural intensity approach. The reducing interior noise method for vibrating cylindrical shells is proposed by altering and redistributing the structural intensity through changing the damping property of the structure. The concept of proposed novel method is based on the properties of structural intensity distribution on cylindrical shells under different load and damping conditions, which can reflects power flow in the structures. In the study, the modal formulas of structural intensity are developed for the steady state vibration of cylindrical shell structures. The detailed formulas of structural intensity are derived by substituting modal quantities, in which the effect of main parameters such as weight coefficients and distribution functions on structure intensity are analyzed and discussed. Numerical simulations are first carried out based on the structural intensity analytical solutions of modal formulas. Through simulating the coupling vibration and acoustical radiation problems of cylindrical shell, the relationship between vibro-acoustic and structural intensity distribution is derived. We find that for cylindrical shell, by properly arranging damping conditions, the structural intensity can be efficiently changed and further the noise property can be improved. The proposed methodology has important implications and potential applications in the vibration and noise control of fuselage structure.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.384-389
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• 2009

In the present paper, dynamic characteristics and vibration control performance of a cylindrical shell structure are experimentally investigated and results are presented in the air and underwater conditions. End-capped cylindrical shell structure is manufactured and Macro-Fiber Composite (MFC) actuators are attached on the inside-surface of the structure. Modal characteristics are studied in the air and under the water conditions and then equation of motion of the structure is derived from the test results. Structural vibration control performances of the proposed structure are evaluated via experiments with optimal control algorithm. Vibration control performances are presented both in the frequency and time domains.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.9
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• pp.899-906
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• 2009

In the present paper, dynamic characteristics and vibration control performance of a cylindrical shell structure are experimentally investigated and results are presented in the air and underwater conditions. End-capped cylindrical shell structure is manufactured and macro-fiber composite(MFC) actuators are attached on the inside-surface of the structure. Modal characteristics are studied in the air and under the water conditions and then equation of motion of the structure is derived from the test results. Structural vibration control performances of the proposed structure are evaluated via experiments with optimal control algorithm. Vibration control performances are presented both in the frequency and time domains.

• Journal of Ocean Engineering and Technology
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• v.29 no.1
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• pp.9-15
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• 2015

We investigated the Reynolds number effects on the flow over a twisted offshore structure in the range of 3×10³≤ Re ≤ 1 × 10⁴. To analyze the effect of the twisted surface treatment, a large eddy simulation (LES) with a dynamic subgrid model was employed. A simulation of the cylindrical structure was also carried out to compare the results with those of the twisted offshore structure. As Re increased, the mean drag and lift coefficient of the twisted offshore structure increased with the same tendency as those of the cylindrical structure. However, the increases in the mean drag and lift coefficient of the twisted offshore structure were much smaller than those of the cylindrical structure. Furthermore, elongated shear layer and suppressed vortex shedding from the twisted offshore structure occurred compared to those of the cylindrical cylinder, resulting in a drag reduction and suppression of the vortex-induced vibration (VIV). In particular, the twisted offshore structure achieved a significant reduction of over 96% in VIV compared with that of the cylindrical structure, regardless of increasing Re. As a result, we concluded that the twisted offshore structure effectively controlled the flow structures with reductions in the drag and VIV compared with the cylindrical structure, irrespective of increasing Re.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.5
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• pp.389-395
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• 2019

Turret mooring type Floating Production Storage and Offloading (FPSO) is designed to rotate the hull around a turret system. The system is mounted inside a cylindrical moon-pool structure of the ship hull structure. The upper part of the moon-pool structure called Bogie Support Structure (BSS) is supported on ring type rail structure (bogie), so high roundness is required at the top of the structure. In this study, the deformation measured during BSS installation was compared with the predicted values through the thermal elasto-plastic analysis, and the causes of deformation were analyzed. Deformation behavior of cylindrical structure with a very large diameter compared to the thickness was investigated. In addition, a proper welding sequence and correction method for the deformed structure were proposed. This study can be an example of the solution to the tolerance problem of large cylindrical structures.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.1
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• pp.7-15
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• 2021

Buckling of cylindrical structures has been extensively researched, because it is an important phenomenon to be considered in structural design. However, the evaluation of thermal effects on the buckling of cylindrical structures has been insufficient; therefore, this study evaluates this thermal effect using shell elements. In addition, the thermal effect on the buckling of temperature-dependent nonlinear materials was evaluated. Nonlinear and linear buckling analyses were performed using the arc-length method to investigate the behavioral characteristics of a cylindrical structure. The basic theory of the linear buckling analysis of a cylindrical structure subjected to thermal stress was derived and presented by applying the thermal stress basic theory.

• 한국태양에너지학회:학술대회논문집
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• 2008.04a
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• pp.348-358
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• 2008

Unlike structures in the air, the vibration analysis of a submerged or floating structure such as offshore structures is possibly only when the fluid-structures is understood, as the whole or part of the structure is in contact with water. Through the comparision between the experimental result and the finite element analysis result for a simple cylindrical model, it was verified that an added mass effects on the cylindrical structure. Using the commercial FEA program ANSYS(v.11.0), underwater added mass was superposed on the mass matrix of the structure. A frequency response analysis of forced vibration in the frequency considered the dynamic load was also performed. It was proposed to find the several important modes of resonance peak for these fixed cylindrical type structures. Furthermore, it is expected that the analysis method and the data in this study can be applied to a dynamic structural design and dynamic performance evaluation for the ground and marine purpose of power generator by wind.