• Journal of Biosystems Engineering
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• v.26 no.1
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• pp.57-66
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• 2001

This study was performed to determine adsorption equilibrium moisture contents of rough rice, brown rice, white rice and rice hull grown in Korea. EMC values were measured by static method using saturated salt solutions at three temperature levels of 20$\^{C}$, 30$\^{C}$ and 40$\^{C}$, and eight relative humidity levels in the range from 11.2% to 85.0%. The measured EMC values were fitted to modified Henderson, Chung-Pfost, and modified Oswin models by using nonlinear regression analysis. The results of comparing root mean square errors for three models showed that modified Henderson and Chung-Pfost models could serve as good models, and that modified Oswin model could not be applicable to rough rice, brown rice, white rice and rice hull.

• Structural Engineering and Mechanics
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• v.19 no.4
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• pp.459-475
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• 2005

This paper deals with a novel application of the Generalized Differential Quadrature (G.D.Q.) method to the linear elastic static analysis of isotropic rotational shells. The governing equations of equilibrium, in terms of stress resultants and couples, are those from Reissner-Mindlin shear deformation shell theory. These equations, written in terms of internal-resultants circular harmonic amplitudes, are first put into generalized displacements form, by use of the strain-displacements relationships and the constitutive equations. The resulting systems are solved by means of the G.D.Q. technique with favourable precision, leading to accurate stress patterns.

• Tribology and Lubricants
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• v.5 no.2
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• pp.68-76
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• 1989

In this paper, the influence of ram-pressure on the static and dynamic characteristics of infinite width tilting-pad journal bearing is investigated theoretically. The ram-pressure is obtained by assumption of conservation of mechanical energy of the lubricant flow through the leading edge of the pad. The pressure in the lubricating film is numerically calculated using the ram-pressure obtained as the inlet pressure boundary condition of the pad. The static equilibrium state of tilting-pad journal bearing is determined by Newton-Raphson iteration method. A numerical results are presented in graphic form and relationships between the ram-pressure and the static and dynamic characteristics are discussed.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.3
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• pp.226-232
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• 2002

In this work, the quasi-static crawling of the four-bar mechanism is investigated. Since the crawling of the mechanism is based on sliding of contact points of the mechanism with the ground, interaction forces and friction forces at contact points of the mechanism with the ground should be computed. For this purpose, we introduce the concept of imaginary joints to find these forces and treat the closed mechanism as a serial one. Lastly, the required torques for the mechanism to crawl with respect to various configurations of the mechanism on a flat ground with uniform friction coefficient, based on sliding conditions of the mechanism in quasi-static equilibrium, are investigated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.9
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• pp.871-876
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• 2011

In this paper, the equilibrium flight conditions of a Korean Traditional Bangpae Kite with low aspect ratio were analyzed by it's aerodynamic data of wind tunnel test. The data of aerodynamic forces and center of pressure of the Kite were used to calculate the relative length of bridles to satisfy the condition of settling the kite to the static equilibrium steady state between ${\theta}=30^{\circ}{\sim}60^{\circ}$. From this equilibrium flight performance analysis, we obtained ($0.88{\pm}0.02$)c of the rear bridle length corresponding to 0.88c of fixed front bridle length. These results were exact agreement with the relative bridle lengths by Korean classical method.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1016-1021
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• 2004

The need for developing a mathematical model for pad-pivot friction in tilting pad proceeding bearings has been well-recognized, since previous experimental work about the performances of the bearings hypothesized that the friction in the bearings is closely related to their performances. Especially, the sliding friction between pad and pivot in the ball and socket type of the bearings can influence the performance of the bearing. We propose a mathematical model for pad-pivot friction in the ball and socket type, which considers the geometrics of the pad and pivot of the bearings, by assuming the sliding friction in the ball and socket bearing as Coulomb friction. By utilizing the proposed model for pad-pivot friction, we show the analysis of Reynolds equation and energy equation, which explain the thermo-hydrodynamic characteristics of tilting pad proceeding bearings, by taking into account the turbulence and inlet pressure building as well. The results of the study show that the performance of titling-pad proceeding bearings can be greatly influenced by the pad-pivot friction. In particular, we have shown that the analysis of the pad-pivot friction is useful to explain the static proceeding loci and the dynamic characteristics of the ball and socket type of the bearings. Furthermore, for a given operating condition, we can obtain various equilibrium states which satisfy the static equilibrium conditions, by considering the pad-pivot friction.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.1038-1043
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• 2002

The floating ring journal bearing is attraction for high-speed turbo machinery applications, including turbochargers and aircraft accessory equipment, because it is not only simple and easy to make and to replace in the field but also it seems to have adequate high speed stability characteristics. Therefore, an analysis method of dynamic properties of floating ring journal bearing is presented. The static equilibrium locus of inner film and outer film are calculated by using the impedance description. The equivalent stiffness and damping coefficients of floating ring journal bearing are composed by using the equilibrium of torque between inner film and outer film. Then, a stability analysis of turbocharger shaft system supported with floating ring journal bearing has been performed.

• Journal of Advanced Research in Ocean Engineering
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• v.4 no.1
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• pp.25-34
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• 2018

In this study, the behavior of the coupled mooring system and floating body is analyzed. The related works are introduced for the mooring analysis of the floating body. Equations motion are introduced for calculating mooring force connected with the floating body. For formulating the equations of motion, the concept of the constrained force is applied for compact expression of it. The input and output data of the module for calculating mooring force is defined. The static analysis and quasi-static analysis are performed. For the analysis, equilibrium equation for elastic catenary mooring line is used by employing finite element method, and the C# solver is developed in this research. The analysis results are validated by comparing with other research results.

• Tribology and Lubricants
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• v.24 no.6
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• pp.378-385
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• 2008

In foil bearings, the friction between bumps and their mating surfaces is the major factor which exerts great influence on the bearing performance. From this point of view, many efforts have been made to improve the understanding of the influence of the friction on the foil bearing performance by developing a number of analytical models. However, most of them did not consider the hysteretic behavior of the foil structure resulting from the friction. The present work developed the static structural model in which hysteretic behavior of the friction was considered. The foil structure was modeled using finite element method and the algorithm which determines the conditions of the contact nodes and the directions of the friction forces was used to take into account the friction. The developed model was integrated into the foil bearing prediction code to investigate the effects of the friction on the static performance of the bearing. The results of analysis show that multiple static equilibrium positions are presented for the one static load under the influence of the friction, inferring its great effects on the dynamic performance. However, the effect of friction on the minimum film thickness which determines load capacity of the bearing is negligible.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.9
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• pp.733-739
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• 1989

Fixed boundary MHD static equilibrium for the axisymmetric toroidal plasma is analyzed numerically. The Grad-Shafranov equation is solved using finite element method. The toroidal current term is expressed by plasma pressure and toroidal field function. The numerical results are compared to the Solovev analytic equilibrium for the verification of the solution. For SNUT-79 tokamak device in Seoul National University, the flux surfaces, the toroidal current profiles, the safety factor q and average beta values are obtained when the p and g profiles are varied.