• Steel and Composite Structures
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• v.28 no.1
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• pp.51-61
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• 2018

A new I-girder consisted of top concrete-filled tubular flange and corrugated web has been proved to have high resistance to both global buckling of the entire girder and local buckling of the web. This study carries out theoretical analysis and experimental tests for this new I-girder to investigate the stress distribution in the flanges and in the corrugated web. Based on some reasonable assumptions, theoretical equations for calculating the normal stress in the flanges and the shear stress in the corrugated web are presented. To verify the accuracy of the presented equations, experimental tests on two specimens were carried out, and the experimental results of stress distribution were used to assess the theoretical prediction. Comparison between the two results indicates that the presented theoretical equations have enough accuracy for calculating the stress in the new I-girder, and thus they can be used reliably in the design stage.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.4
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• pp.118-125
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• 1992

Theoretical equations for hoop stress, longitudinal or meridian stress and Von Mises stress of an axismmetric conical pressure vessel and a frustum of conical pressure velle, both of which are pressuized by hydrostatic loading, are derived from equilibrium equations. The membrane stresses conputed by theoretical equations for a conical pressure vessel and a frustum of conical pressure vessel are compared with the values obtained from finite elelment method. Based on the fact that the computational values by theoretical equations are well agreed with the finite element results, derived equations are proved to be valid and it is possible for those equations to be conveniently used for structural analysis or design of frustum of conical pressure vessel which is a part of silo body.

• Journal of the Korean Chemical Society
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• v.7 no.3
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• pp.211-215
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• 1963

Inter-relationship between the Hammett equation and the linear enthalpy-entropy effect has been discussed by deriving a new set of equations; ${\Delta}{\Delata}H^{\neq}=a{\sigma}+b{\Delta}{\Delta}S^{\neq}$ and ${\Delta}{\Delta}F^{\neq}=a{sigma}+(b-T){\Delta}{\Delta}S^{\neq}$ where a = -1.36p. Theoretical analysis show that the Hammett, Leffler and Brown equations are special limited forms of these general equations. A necessary and sufficient test of substituent effect can thus be provided by the plot of $({\Delta}{\Delta}H^{\neq}-a{\sigma)$ versus ${\Delta}{\Delta}S^{\neq}$.

• Structural Engineering and Mechanics
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• v.82 no.2
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• pp.191-204
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• 2022

A three-mass vehicle model including one rigid mass and two unsprung masses is adopted to predict the vehicle-bridge interaction (VBI) and to establish the nonlinear coupled governing equations. To overcome the numerical instability and large computation problems concerning the vehicle-bridge system, the perturbation method is used to convert the nonlinear coupled governing equations into a set of linear uncoupled equations. Formulas for bridge's natural frequencies considering both the VBI and the dynamic responses of bridge and vehicle are proposed. Compared with the numerical results obtained by the Newmark-β method, the theoretical solutions for natural frequencies and dynamic responses are validated. The effects of the important factors of unsprung mass, vehicle damping, surface irregularity on the natural frequencies and dynamic responses of bridge and vehicle are discussed, based on the theoretical solutions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.2
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• pp.95-101
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• 2017

In this study, we derived theoretical equations for the zigzag movement of a leading vehicle, which is the most frequent behavior in train accidents, by using a simplified spring-mass model for the rolling stock. In order to solve the equations of motion, we applied the Runge-Kutta method, which is the typical numerical analysis method used for differential equations. Furthermore, the lateral displacement of the wheel-set at the wheel-rail interface was estimated using kinetic energy. In order to verify the derived equations, we compared the theoretical and simulated results under various collision conditions. The maximum relative deviations of the lateral displacements were 0.8 [%] ~ 4.7 [%] in light collisions and 0.6 [%] ~ 5.1 [%] under derailment conditions. When an accident is simulated, these theoretical equations can be used to predict the overall behavior and obtain the offset of the body-to-body link as the initial perturbation.

• Steel and Composite Structures
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• v.47 no.4
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• pp.455-466
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• 2023

To investigate the load bearing capacity of axially preloaded circular hollow section (CHS) stub columns strengthened by carbon fiber reinforced polymer (CFRP), theoretical analysis is carried out. The yield strength and the ultimate strength of a CFRP strengthened preloaded CHS stub column are determined at the yielding of the CHS tube and at the CFRP fracture, respectively. Theoretical models are proposed and corresponding equations for calculating the static strengths, including the yield strength and the ultimate strength, are presented. Through comparison with reported experimental results, the theoretical predictions on the static strengths are proved to be accurate. Through finite element (FE) analyses, parametric studies for 258 models of CFRP strengthened preloaded CHS stub columns are conducted by considering different values of tube diameter, tube thickness, CFRP layer and preloading level. The static strengths of the 258 models predicted from presented equations are proved to be in good agreement with FE simulations when the diameter-to-thickness ratio is less than 90ε². The parametric study indicates that the diameter and the thickness of the steel tube have great effects on CFRP strengthening efficiency, and the recommended ranges of the diameter and the thickness are proposed.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.448-452
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• 1997

Theoretical average current and rms current equations are solved using the analytical method in the 3phase voltage-fed inverter. Experimental switch current equations are established by simulation and compared with theoretical equations. As a result of analysis, average and rms currents of switch devices are represented by a function as power factor and modulation index. Especially, equations of this paper are represented as a function of a single factor(K) equal to the product of the power factor and modulation index. Method that can find current levels of switch devices for inverter design and conduction loss of inverter in a simple and accurate manner is presented. Influences of modulation method on switch current are also studied.

• Bulletin of the Korean Mathematical Society
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• v.53 no.6
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• pp.1725-1739
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• 2016

Abstract. Numerical solutions for the evolutionary space fractional order differential equations are considered. A predictor corrector method is applied in order to obtain numerical solutions for the equation without solving nonlinear systems iteratively at every time step. Theoretical error estimates are performed and computational results are given to show the theoretical results.

• East Asian mathematical journal
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• v.37 no.3
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• pp.295-305
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• 2021

In this paper, we analyze the efficiency of a domain decomposition method for the two-dimensional telegraph equations. We formulate the theoretical spectral radius of the iteration matrix generated by the domain decomposition method, because the rate of convergence of an iterative algorithm depends on the spectral radius of the iteration matrix. The theoretical spectral radius is confirmed by the experimental one using MATLAB. Speedup and operation ratio of the domain decomposition method are also compared as the two measurements of the efficiency of the method. Numerical results support the high efficiency of the domain decomposition method.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.7
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• pp.39-47
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• 1992

This paper showed that theoretical site attenuation curves were obtained simply by the method of moments analysis for current integral equations on antennas. Since the expansion coefficients of driving and receiving points were calculated from the method of moments procedure, site attenuations were evaluated simply using these basic antenna parameters. Theoretical site attenuations were calculated with half-wave resonant dipoles connected directly to a 50 ohm receiving system and connected to a 72/50 ohm matching network, respectively. Results were compared with other theoretical studies reported so far. Also included were experimental results for site attenuations to prove the validity of theoretical analysis.