• International Journal of Naval Architecture and Ocean Engineering
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• 제8권6호
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• pp.530-536
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• 2016

The number of fabrication shop for spherical type LNG tank is proportional to that of the tank radius to be constructed. Due to limitation of facility investment including building sites, it is practically difficult to fabricate various size tanks with perfectly spherical shape in the yards. The efficient method to be capable of increasing cargo tank volume is to extend vertically the conventional spherical type LNG tank by inserting a cylindrical shell structure. The main purpose of this study is to derive related equations on forces generated on spherical type LNG tank with central cylindrical part under various static loadings in order to establish the simplified analysis method for the initial estimate. In this study, equations on circumferential and meridional force have been derived and verified by relations with the reaction forces per unit length of equator.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.1056-1060
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• 1997

An optical technique to align the laser beam with the rotation axis of a cylindrical microstructure is developed for laser microfabrication. The sample surface is first set normal to the rotation axis by applying a simple reflection law of geometrical optics and then the laser beam is aligned with the rotation axis using translation stages with quadrant photodiodes. Principle and the configuration of the alignment technique are described. An application of the present technique to laser microstereolithography showed that it could be effectively used for fabrication of micro cylindrical structures.

• Steel and Composite Structures
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• 제24권5호
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• pp.591-602
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• 2017

A cable-stiffened cylindrical single-layer latticed shell that is reinforced by cable-stiffened system has superior stability behaviour compared with the ordinary cylindrical latticed shell. The layouts of cable-stiffened system are flexible in this structural system, and different layouts contribute different stiffness to the structure. However, the existed few research primarily focused on the simplest type of cable layouts, in which the grids of the latticed shell are diagonally stiffened by prestressed cables in-plane. This current work examines the stability behaviour of the cable-stiffened cylindrical latticed shells with two different types of cable layouts using nonlinear finite element analysis. A parametric study on the effect of cross-sectional of the cables, pretension in cables, joint stiffness, initial imperfections, load distributions and boundary conditions is presented. The findings are useful for the reference of the designer in using this type of structural system.

• Journal of the Optical Society of Korea
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• 제20권1호
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• pp.64-69
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• 2016

A new compact conformal dome optical system was established, and the aberration characteristics of the dome were investigated using Zernike aberration theory. The aberrations induced by the dome at different fields of regard (FORs) from 30° to 100° were effectively balanced by a rotating cylindrical lens. This kind of optical system can be widely used in top-view optical searching devices. A design method was introduced and the optimization results analyzed in detail. The results showed that the Zernike aberrations produced by the conformal dome were decreased dramatically. Also, a complete conformal optical system was designed, to further illustrate the aberration correction effect of the rotating cylindrical lens. Using a cylindrical lens not only provided a large FOR, but also simplified enormously the structure of the conformal optical system.

• 한국소음진동공학회논문집
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• 제11권4호
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• pp.43-51
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• 2001

An experimental modal analysis is the process to identify structure's dynamic characteristics such as resonant frequencies, damping values and mode shapes. An experimental model was made of stainless steel in the shape of a circular cylindrical shell and installed on the test bed with jigs. For investigating vibrational characteristics of the continuous circular cylindrical shell with intermediate supports, modal testing is performed by using impact hammer, accelerometer and 8-channel FFT analyzer. The frequency response function(FRF) measurements are also made on the experimental model within the frequency range from 0 to 4kHz. Modal parameters are identified from resonant peaks in the FRF's and animated deformation patterns associated with each of the resonances are shown on a computer screen. The experimental results are compared with analytical and FEA results.

• Structural Engineering and Mechanics
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• 제75권1호
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• pp.87-100
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• 2020

The present paper investigates the combination resonance behavior of imperfect spiral stiffened functionally graded (SSFG) cylindrical shells with internal and external functionally graded stiffeners under two-term large amplitude excitations. The structure is embedded within a generalized nonlinear viscoelastic foundation, which is composed of a two-parameter Winkler-Pasternak foundation augmented by a Kelvin-Voigt viscoelastic model with a nonlinear cubic stiffness, to account for the vibration hardening/softening phenomena and damping considerations. With regard to classical plate theory of shells, von-Kármán equation and Hook law, the relations of stress-strain are derived for shell and stiffeners. The spiral stiffeners of the cylindrical shell are modeled according to the smeared stiffener technique. According to the Galerkin method, the discretized motion equation is obtained. The combination resonance is obtained by using the multiple scales method. Finally, the influences of the stiffeners angles, foundation type, the nonlinear elastic foundation coefficients, material distribution, and excitation amplitude on the system resonances are investigated comprehensively.

• Journal of information and communication convergence engineering
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• 제7권3호
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• pp.263-267
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• 2009

Cylindrical monopole antenna is one of most promising candidates for multi-band applications such as PCS, WLAN, DMB, and UWB wireless services. In this research, we demonstrate that there exist two types of current distributions according to the exciting frequency in a double band cylindrical monopole antenna, in which double resonance is achieved by adjusting the coupling structure of the antenna base. The operating modes of current distributions are identified from CST software simulations, the standing wave mode in a lower band and the traveling wave mode in a higher band. Also it is noticed that the mode behavior is quite similar to a helical antenna, a standing-wave (resonance) mode and a traveling-wave (non-resonance) mode according to the electrical dimensions of antenna. The effective ranges for operating modes and design formulas of the double band antenna are derived from simulation and measured results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1229-1234
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• 2006

This paper is concerned with the dynamic modeling and controller design for a cylindrical shell equipped with MFC actuators. The dynamic model was derived by using Ravleigh-Ritz method based on Donnel-Mushtari shell theory. The boundary conditions at both ends were assumed to be shear diaphragm. To verify the theoretical results, a cylindrical shell structure made of aluminum was built ana tested by using impact hammer. Experimental results show that there are little discrepancies compared to theoretical results because of the boundary conditions at both ends. The MFC actuators were glued to the cylindrical shell in longitudinal and circumferential directions. The PPF controller were designed for lowest two modes and applied to the MFC actuators. The experimental results show that vibrations can be successfully suppressed.

• Structural Engineering and Mechanics
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• 제38권6호
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• pp.753-765
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• 2011

The radial vibration behaviors of a circular cylindrical composite piezoelectric transducer (CPT) are investigated. The CPT is composed of a piezoelectric ring polarized in the radial direction and an elastic ring graded in power-law variation form along the radial direction. The governing equations for plane stress state problem under the harmonic excitation are derived and the exact solutions for both piezoelectric and functionally graded elastic rings are obtained. The characteristic equations for resonant and anti-resonant frequencies are established. The presented methodology is fit to carry out the parametric investigation for composite piezoelectric transducers (CPTs) with arbitrary thickness in radial direction. With the aid of numerical analysis, the relationship between the radial vibration behaviors of the cylindrical CPT and the material inhomogeneity index of the functionally graded elastic ring as well as the geometric parameters of the CPTs are illustrated and some important features are reported.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.911-916
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• 2003

A method for the dynamic analysis of thin-walled cylindrical shell conveying steady fluid flow presents. The dynamics of thin-walled shell is based on Sanders' theory and the fluid flow in cylindrical shell is treated inviscid, incompressible fluid. A dynamic coupling conditions at fluid-structure interface is used. The equations of motion are solved by a finite element method and validated by comparing the natural frequency with other published results and Nastran. The influence of fluid velocity on the frequency response function is illustrated and discussed.