• Computers and Concrete
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• v.15 no.2
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• pp.259-277
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• 2015

The lack of experimental studies on the mechanical behavior of reinforced concrete (RC) haunched beams leads to difficulties in statistical and reliability analyses. This study performs stochastic and reliability analyses of the ultimate shear capacity of RC haunched beams based on nonlinear finite element analysis. The main aim of this study is to investigate the influence of uncertainty in material properties and geometry parameters on the mechanical performance and shear capacity of RC haunched beams. Firstly, 65 experimentally tested RC haunched beams and prismatic beams are analyzed via deterministic nonlinear finite element method by a special program (ATENA) to verify the efficiency of utilized numerical models, the shear capacity and the crack pattern. The accuracy of nonlinear finite element analyses is verified by comparing the results of nonlinear finite element and experiments and both results are found to be in a good agreement. Afterwards, stochastic analyses are performed for each beam where the RC material properties and geometry parameters are assigned to take probabilistic values using an advanced simulating procedure. As a result of stochastic analysis, statistical parameters are determined. The statistical parameters are obtained for resistance bias factor and the coefficient of variation which were found to be equal to 1.053 and 0.137 respectively. Finally, reliability analyses are accomplished using the limit state functions of ACI-318 and ASCE-7 depending on the calculated statistical parameters. The results show that the RC haunched beams have higher sensitivity and riskiness than the RC prismatic beams.

• Journal of Korean Medicine Rehabilitation
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• v.30 no.2
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• pp.125-137
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• 2020

Objectives The purpose of this study was to examine how changes in the cervical spine correlate with body posture changes in the whole body, and to find out the significance of complementary clinical application X-ray and Chuna posture analysis. Methods From January 1, 2019 to October 31, 2019, the results of 27 patients with pain in the vertebral region were analysed in accordance with the results of cervical X-ray and Chuna posture analysis. In order to confirm the significance of Chuna posture analysis results, the survey of 187 Chuna standard curriculum instruction qualification certifiers was conducted and the responses of 47 of them were analyzed. Results The occiput-atlas cline angle increases in both hypolordosis/hyperlordosis groups based on cervical lordosis angle, and increases further than in the hyperlordosis group. There were significant correlations between the changes in the cervical spine and the body posture changes in the whole body. There were no significant differences between cervical X-ray sagittal parameters and the body posture analysis parameters based on the patient's major disease codes. Conclusions As a result of conducting a survey on the clinical importance of the body posture analysis parameters, the importance of cervical parameters was verified. Changes in the cervical spine may not only cause other changes in the cervical region, but also affect the body posture changes in the whole body. The complementary application of X-ray and Chuna posture analysis results is helpful in clinical diagnosis and treatment of musculoskeletal disorders.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.321-322
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• 2002

This paper presents study of effects of cutting parameters such as cutting speed, feed rate and depth of cut on the surface roughness in hard turning. Taguchi Method and linear regression model of design parameters were utilized to identify the controlling process parameters that can monitor the surface roughness in the hard turning operation. In the process optimization, experimental planning was performed using the orthogonal array and concept of the signal-to-noise ratio. Cutting parameters such as speed, feed rate, and depth of cut were selected as process parameters and the ANOVA analysis showed that feed rate and cutting speed had more effect on the roughness variation that depth of cut.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.35.2-35.2
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• 2013

I will present a new approach to constrain galaxy physical parameters from the combined interpretation of stellar and nebular emission in wide ranges of observations. This approach relies on a comprehensive library of synthetic spectra, assembled using state-of-the-art models of star formation and chemical enrichment histories, stellar population synthesis, nebular emission and attenuation by dust. We focus on the constraints set by 5-band photometry and low- and medium-resolution spectroscopy at optical rest wavelengths on a few physical parameters characterizing the stars and interstellar medium. Since these parameters cannot be known a priori for any galaxy sample, we assess the accuracy to which they can be retrieved by simulating 'pseudo-observations' using models with known parameters. We find that the combined analysis of stellar and nebular emission in low-resolution (50A FWHM) galaxy spectra provides valuable constraints on all physical parameters. The approach can be extended to the analysis of any type of observation and during this talk i will present some applications to observed galaxies up to redshift 1.5.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.625-632
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• 2012

Optimization of process parameters in polymer extrusion is an important task to reduce manufacturing cost. To determine the optimum values of the process parameters, it is essential to find their influence on the strength of polymer breathable thin film. The significance of six important process parameters namely, extruder cylinder temperature, extruder speed, extruder dies temperature, cooling roll temperature, stretching ratio, stretching roll temperature on breathable film strength of polymer extrusion was determined. Moreover, this paper presents the application of Taguchi method and analysis of variance (ANOVA) for maximization of the breathable film strength influenced by extrusion parameters. The optimum parameter combination of extrusion process was obtained by using the analysis of signal-to-noise ratio. The conclusion revealed that extruder speed and stretching ratio were the most influential factor on the film strength, respectively. The best results of film strength were obtained at higher extruder speed and stretching ratio.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.55-57
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• 1997

This paper develops the advanced method for the calculation of the equivalent circuit parameters of induction motor. An Induction motor is magnetically coupled system. But the conventional motor (the permeance method) calculates the each component of parameters separately. And it highly depends on the experimental factors and experiences to compensate the errors due to the some assumptions. Rut the proposed method calculates the parameters fully from the results of 2 dimensional finite element analysis. So the complexity in geometry and the non linearity of induction motor can be considered. And the computational cost is reduced compared with the conventional field and circuit approach. The results are compared with parameters from the permeance method. And it is verified by the comparison with the experimental results.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.61-63
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• 1999

This paper presents an efficient method for analysis of magnetodynamic system using frequency-dependent parameters. In equivalent electric circuit of linear magnetodynamic system, parameters of inductance and resistance are not constant since they vary with its driving frequency. Once frequency-dependent parameters of equivalent electric circuit for a given system are extracted, they can be used to analyze various characteristics of system. We use the Fourier transform, the high-order sensitivity method and Taylor series in order to efficiently extract the frequency-dependent parameters of magnetodynamic system. The proposed algorithm is applied to an induction heating system to validate its numerical efficiency.

• Structural Engineering and Mechanics
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• v.55 no.4
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• pp.687-702
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• 2015

A method based on derivatives of eigen-parameters is presented for damage detection in discrete systems with dampers. The damage is simulated by decrease on the stiffness coefficient and increase of the damping coefficient. In the forward analysis, the derivatives of eigen-parameters are derived for the discrete system. In the inverse analysis, a derivative of eigen-parameters based model updating approach is used to identify damages in frequency domain. Two numerical examples are investigated to illustrate efficiency and accuracy of the proposed method. Studies in this paper indicate that the proposed method is efficient and robust for both single and multiple damages and is insensitive to measurement noise. And satisfactory identified results can be obtained from few numbers of iterations.

• Structural Engineering and Mechanics
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• v.13 no.2
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• pp.117-134
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• 2002

This paper presents a computational method for a confidence region of identified parameters which are affected by measurement noise and error contained in prescribed parameters. The method is based on sensitivities of the identified parameters with respect to model parameter error and measurement noise along with the law of error propagation. By conducting numerical experiments on simple models, it is confirmed that the confidence region coincides well with the results of numerical experiments. Furthermore, the optimum arrangement of sensor locations is evaluated when uncertainty exists in prescribed parameters, based on the concept that square sum of coefficients of variations of identified results attains minimum. Good agreement of the theoretical results with those of numerical simulation confirmed validity of the theory.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.85-101
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• 2020

The optimal parameters for the fluid-structure interaction analysis using the Smoothed Particle Hydrodynamics (SPH) for fluids and finite elements for structures, respectively, are explored, and the effectiveness of the simulations with those parameters is validated by solving several open surface fluid problems. For the optimization of the Equation of State (EOS) and the simulation parameters such as the time step, initial particle spacing, and smoothing length factor, a dam-break problem and deflection of an elastic plate is selected, and the least squares analysis is performed on the simulation results. With the optimal values of the pivotal parameters, the accuracy of the simulation is validated by calculating the exerted force on a moving solid column in the open surface fluid. Overall, the SPH-FEM coupled simulation is very effective to calculate the fluid-structure interaction. However, the relevant parameters should be carefully selected to obtain accurate results.