• The Journal of the Acoustical Society of Korea
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• v.18 no.4E
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• pp.20-25
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• 1999

To get accurate natural frequencies of an engine crankshafts, finite element equations of motion are developed, taking real geometries of the shaft into account. For the crankshaft with wide crank webs, a specialized rotating web element is developed. This includes the effects of rotary inertia, gyroscopic moment, and shear. After the finite element equations are constructed, eigenvalues are extracted from the system equations to get natural frequencies, based on the Sturm sequence method which exploits the banded forms of the system matrices to reduce computations. The scheme developed can be used for the free vibration analysis of any type of spinning structures which include skew symmetric gyroscopic moment matrix in the system matrices. The results are compared with experimental data in order to confirm the study.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.1
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• pp.78-87
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• 1998

In this study, semi-rigid light-weight framed structures analysis model (SERIFS) was developed by advancing the LEIFS model. This model enables us to analyze simultaneous effects of large deflection and semi-rigid connection by computing unbalanced load occurring in the process of repeated loading through equalization of bending moments and torsion. This model is also able to handle the effect of the semi-rigid connection and large deflection by modifying the elastic stiffness matrix using moment-rotation behavior of connection. Moment-rotation behavior of the semi-rigid connection was adopted from the experimental results of load-vertical displacement of frame element In conclusion, this model achieves to analyze the nonlinear and large deflection behavior on the semi-rigid and light-weight steel frame connection.

• Journal of Advanced Marine Engineering and Technology
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• v.2 no.1
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• pp.3-14
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• 1978

The authors have developed a calculating method of propeller shaft alignment by the finite element method. The propeller shaft is divided into finite elements which can be treated as uniform section bars. For each element, the nodal point equation is derived from the stiffness matrix, the external force vector and the section force vector. Then the overall nodal point equation is derived from the element nodal point equation. The deflection, offset, bending moment and shearing force of each nodal point are calculated from the overall nodal point equation by the digital computer. Reactions and deflections of supporting points of straight shaft are calculated and also the reaction influence number is derived. With the reaction influence number the optimum alignment condition that satisfies all conditions is calculated by the simplex method of linear programming. All results of calculation are compared with those of Det norske Veritas, which has developed a computor program based on the three-moment theorem of the strength of materials. The authors finite element method has shown good results and will be used effectively to design the propeller shaft alignment.

• Bulletin of the Korean Chemical Society
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• v.19 no.9
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• pp.985-993
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• 1998

The second order effective valence shell Hamiltonian ($H^v$), which is based on quasidegencrate many-body perturbation theory, is applied to determining the potential energy surfaces and the dipole moment functions of the various valence states of $NH_2$. The $H^v$ calculated values are found to be in good agreement with those of other ab initio calculations or experiments. It signifies the fact that the $H^v$ is a good ab initio method to describe the energies and properties of various valence states with a same chemical accuracy. Furthermore, it is shown that the lowest (second order for energy and the first order for property) order $H^v$ method is very accurate for small molecules like $NH_2$ and the matrix elements of Hv which are computed only once are all we need to accurately describe all the valence states simultaneously.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.54-62
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• 1998

In this study, collapse behavior of frame composed of thin-walled rectangular tube is investigated. Considering the collapse of frame, the bending and compression members undergo large deformation. The stiffness of the compound element is obtained from analytical moment-rotation relationship and approximated load-deflection relationsh- ip of thin-walled rectangular tube. A computer program is developed for the large deformation analysis of frame. An incremental displacement method is used in the program and at each incremental stage, the stiffness matrix of the total structure is checked with the state of each element for bending and compression.

• Journal of Mechanical Science and Technology
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• v.19 no.9
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• pp.1731-1741
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• 2005

In this paper, we studied about the effect of the open crack and a tip mass on the dynamic behavior of a cantilever pipe conveying fluid with a moving mass. The equation of motion is derived by using Lagrange's equation and analyzed by numerical method. The cantilever pipe is modelled by the Euler-Bernoulli beam theory. The crack section is represented by a local flexibility matrix connecting two undamaged pipe segments. The influences of the crack, the moving mass, the tip mass and its moment of inertia, the velocity of fluid, and the coupling of these factors on the vibration mode, the frequency, and the tip-displacement of the cantilever pipe are analytically clarified.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.6
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• pp.420-425
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• 2015

In this paper a transfer matrix method is developed to solve for bending vibration of beam with linearly reduced width, and subsequently used to determine the exact natural frequencies for such problems. The differential equation, shear force, and bending moment are derived from Hamilton's principle, and the roots of the differential equation are computed using the power series solution of the Frobenius method. The effect of various taper ratio for bending vibration of beam with linearly reduced width is investigated in detail, and to validate the accuracy of the proposed method the results computed are compared with those given from commercial software(ANSYS).

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.6
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• pp.44-52
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• 1997

As part of the effort to reduce the weight of powertrain, a hollow crankshaft has been designed. The mass reduction of the crankshaft changes the dynamic properties of the crankshaft such as moment of inertia, and torsional, bending stiffness. The purpose of this paper is to compare the dynamic behavior of the hollow crankshaft with that of the original, solid crankshaft. Global dynamic behavior of the crankshaft is analyzed bgy the transfer matrix method(TMM). The crankshaft has been modeled by 38 lumped mass and stiffness elements. The dynamic patameters of each lumped element are provided by Finite Element Method(FEM). The responses of the crankshaft from TMM are fed back as loading conditions to the Finite Element model to obtain dynamic stresses for critical areas of the crankshaft.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2023-2029
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• 2016

This paper addresses a robust controller design technique for a nonlinear underwater glider with disturbances. We consider the buoyancy and pitching moment as control inputs, which generate additional nonlinearity on the plant dynamics. To deal with the nonlinearity, we utilize the optimal linearization technique. The conditions for the optimal linearization and the controller design are formulated in terms of matrix inequalities. The effectiveness of the proposed method is demonstrated through a simulation.

• Structural Engineering and Mechanics
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• v.39 no.2
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• pp.169-186
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• 2011

This paper is devoted to the development of the equations which describe the elastic response of a curved laminate subjected to in-plane loads and bending moments. Similar to the classic $6{\times}6$ ABD matrix constitutive relation of a flat laminate, a new $6{\times}6$ matrix constitutive relation between force resultants, moment resultants, mid-plane strains and deformed curvatures for a curved laminate is formulated. This curved lamination theory will provide the fundamental basis for the analyses of curved laminated structures. The stress predictions by the present curved lamination theory are compared to those by the curved laminate analysis that neglected the nonlinear terms in the derivation of the constitutive relation. The results show that the curved laminate analysis that neglected the nonlinear terms cannot reflect the effect of curvature and can no longer predict the stresses accurately as the curvature becomes noticeable. In this paper, a curved lamination theory that retains the nonlinear terms and, therefore, accounts for the effect of the non-flat geometry of the structure will be developed.