• Structural Engineering and Mechanics
• /
• v.34 no.4
• /
• pp.491-505
• /
• 2010

A computational analysis of the nonlinear free vibration of corrugated annular plates with shallow sinusoidal corrugations under uniformly static ambient temperature is examined. The governing equations based on Hamilton's principle and nonlinear bending theory of thin shallow shell are established for a corrugated plate with a concentric rigid mass at the center and rotational springs at the outer edges. A simple harmonic function in time is assumed and the time variable is eliminated from partial differential governing equations using the Kantorovich averaging procedure. The resulting ordinary equations, which form a nonlinear two-point boundary value problem in spatial variable, are then solved numerically by shooting method, and the temperature-dependent characteristic relations of frequency vs. amplitude for nonlinear vibration of heated corrugated annular plates are obtained. Several numerical results are presented in both tabular and graphical forms, which demonstrate the accuracy of present method and illustrate the amplitude frequency dependence for the plate under such parameters as ambient temperature, plate geometry, rigid mass and elastic constrain.

• The Bulletin of The Korean Astronomical Society
• /
• v.40 no.1
• /
• pp.49.2-49.2
• /
• 2015

IntraCluster Medium (ICM) located at the galaxy cluster is in the state of very hot, tenuous, magnetized, and highly ionized X-ray emitting plasmas. High temperature and low density make ICM very viscous and conductive. In addition to the high conductivity, fluctuating random plasma motions in ICM, occurring at all evolution stages, generate and amplify the magnetic fields in such viscous ionized gas. The amplified magnetic fields in reverse drive and constrain the plasma motions beyond the viscous scale through the magnetic tension. Moreover, without the influence of resistivity viscous damping effect gets balanced only with the magnetic tension in the extended viscous scale leading to peculiar ICM energy spectra. This overall collisionless magnetohydrodynamic (MHD) turbulence in ICM was simulated using a hyper diffusivity method. The results show the plasma motions and frozen magnetic fields have power law of $E_V^k{\sim}k^{-3}$, $E_M^k{\sim}k^{-1}$. To explain these abnormal power spectra we set up two simultaneous differential equations for the kinetic and magnetic energy using an Eddy Damped Quasi Normal Markovianized (EDQNM) approximation. The solutions and dimensions of leading terms in the coupled equations derive the power spectra and tell us how the spectra are formed. We also derived the same results with a more intuitive balance relation and stationary energy transport rate.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.5 no.1
• /
• pp.154-161
• /
• 1997

This paper presents the method to eliminate the constraint reaction in the Lagrange multiplier form equation of motion by using a generalized coordinate driveder from the velocity constraint equation. This method introduces a matrix method by considering the m dimensional space spanned by the rows of the constraint jacobian matrix. The orthogonal vectors defining the constraint manifold are projected to null vectors by the tangential vectors defined on the constraint manifold. Therefore the orthogonal projection matrix is defined by the tangential vectors. For correcting the generalized position coordinate, the optimization problem is formulated. And this correction process is analyzed by the quasi Newton method. Finally this method is verified through 3 dimensional vehicle model.

• Journal of the Korean Society of Safety
• /
• v.11 no.2
• /
• pp.116-121
• /
• 1996

On the stability of Timoshenko cantilever beam subjected to a follower force, the influence of the characteristics of elastic constraints at the free end Is studied. The equations of motion and boundary conditions of this nonconservative elastic system are estabilished by using the Hamilton's principle. Upon evaluation of the stability of this system, the effect of shear deformation and rotatory inertia is considered in calculation. Using cowper's formulae Timoshenko's shear coefficient K'are determined. From this imvestigation it is found that the constrain parameter have an appreciable stabilizing effect in this nonconservative system. Moreover, it is obvious that the small values of K'decrease the flutter load of this system.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.523-528
• /
• 2008

An open frame structure is fastened by bolt joints for strength and shock attenuation. Therefore the full finite element model of an open frame structure should be properly modeled including bolt joints for strength analysis of the frames and joint assemblies which are operated under multi-loading conditions such as driving, drop, inertia and torsional loads. Then the joints and frames must satisfy the specified allowable strength constraints. Because the full finite element model has a large number of elements to perform strength analysis, a detailed fine bolt analysis seems to be very expensive. Therefore bolts of the full finite element model are approximately modeled by constraints equations to constrain degree of freedoms between adjacent nodes. However, the constraints equation method can exaggerate stress results at the constrained nodes. Thus a detailed bolt analysis and a theoretical/experiential formula of bolts for a worst bolt joint are performed using reaction force applied both bolt and bolt joint. Finally, the results from the two methods are compared and discussed to verify the safety of the open frame structure.

• Journal of KIISE:Computer Systems and Theory
• /
• v.36 no.5
• /
• pp.404-411
• /
• 2009

We introduce in this paper a new method for smooth foldover-free warping of images, based on the vector field deformation technique proposed by Von Funck et al. It allows users to specify the constraints in two different ways: positional constraints to constrain the position of a point in the image and gradient constraints to constrain the orientation and scaling of some parts of the image. From the user-specified constraints, it computes in the image domain a C1-continuous velocity vector field, along which each pixel progressively moves from its original position to the target. The target positions of the pixels are obtained by solving a set of partial derivative equations with the 4th order Runge-Kutta method. We show how our method can be useful for texture mapping with hard constraints. We start with an unconstrained planar embedding of a target mesh using a previously known method (Least Squares Conformal Map). Then, in order to obtain a texture map that satisfies the given constraints, we use the proposed warping method to align the features of the texture image with those on the unconstrained embedding. Compared to previous work, our method generates a smoother texture mapping, offers higher level of control for defining the constraints, and is simpler to implement.

• International Commerce and Information Review
• /
• v.14 no.3
• /
• pp.307-322
• /
• 2012

The purpose of this paper is to examine determinants of export to the East Asia region, using panel unit root, panel cointegration framework, panel VECM (vector error correction model), panel FMOLS (fully modified OLS). Different panel unit root tests confirm that the data series are integrated processes with unit roots. When applying cointegration tests to long-run effect for aggregate panel data, a primary concern is to construct the estimators in a way that does not constrain the transitional dynamics to be similar among different countries of the panel. The regression equations are estimated by various panel cointegration estimators. The panel data causality results reveal that exchange rates has unidirectional effects on export and GDP, and there exists bidirectional causality between export and GDP. Also, the results from the panel FMOLS tests overwhelmingly reject the null hypothesis of zero coefficient. The panel cointegrating vectors show that the export has positive relationship with the GDP and ODI (overseas direct investment).

• Fire Science and Engineering
• /
• v.29 no.5
• /
• pp.51-56
• /
• 2015

In this study, optimal design methods were applied to the agent discharge flow of clean agent fire extinguishing systems. The methods combined optimal design theory and engineering theory for engineering analysis in a design program or coast savings in value engineering. Optimal design parameters were determined to optimize the agent discharge flow based on the design theory of the clean agent fire extinguishing systems and the theory of optimal design. The design factors were verified in regard to suitability for the performance of fire extinguishing systems. The results provide a foundation for optimal design method methods in other fire extinguishing systems. Optimization of the agent discharge flow of the discharge nozzle was confirmed by the constraints on the inner diameter of the discharge nozzle and the pipe, agent arrival time, flow, and pressure variation of the agent. The deviation of discharge pressure and agent time of the agent discharge nozzle were found to correlate with the pressure variation.

• Asian-Australasian Journal of Animal Sciences
• /
• v.16 no.1
• /
• pp.116-123
• /
• 2003

Forages are the most important feed resource for ruminants worldwide, whether fed as pastures, forage crops or conserved hay, silage or haylage. There is large variability in the quality of forages so measurement and prediction of feeding value and nutritive value are essential for high levels of production. Within a commercial animal production system, methods of prediction must be inexpensive and rapid. At least 50% of the variation in feeding value of forages is due to variation in voluntary feed intake. Identification of the factors that constrain voluntary feed intake allows these differences to be managed and exploited in forage selection. Constraints to intake have been predicted using combinations of metabolic and physical factors within the animal while simple measurements such as the energy required to shear the plant material are related to constraints to intake with some plant material. Animals respond to both pre- and post-ingestive feedback signals from forages. Pre-ingestive signals may play a role in intake with signals including taste, odour and texture together with learned aversions to nutrients or toxins (post-ingestive feedback signals). The challenge to forage evaluation is identification of the factors which are most important contributors to these feedback signals. Empirical models incorporating chemical composition are also widely used. The models tend to be useful within the ranges of the datasets used in their development but none can claim to have universal application. Mechanistic models are becoming increasingly complex and sophisticated and incorporate both feed characteristics and use of biochemical pathways within the animal. Improvement in utilisation through the deliberate selection of pasture plants for high feeding value appears to have potential and has been poorly exploited. Use of Near Infrared Reflectance Spectroscopy is a simple method that offers significant potential for the preliminary screening of plants with genetic differences in feeding value. Near Infrared Reflectance Spectroscopy will only be as reliable as the calibration sets from which the equations are generated.

• Journal of Korean Association for Spatial Structures
• /
• v.12 no.2
• /
• pp.89-98
• /
• 2012

This study investigates the optimum structural design of space truss considering global buckling, and is to obtain the minimal weight of the structure. The mathematical programming method is used for optimization of each member by member force. Besides, dynamic programming method is adapted for consideration in snap-through buckling. The mathematical modeling for optimum design of truss members consists of objective function of total weight and constrain equations of allowable tensile (or compressive) stress and slenderness. The tangential stiffness matrix is examined to find the critical point on equilibrium path, and a ratio of the buckling load to design load is reflected in iteration procedures of dynamic programming method to adjust the stiffness of space truss. The star dome is examined to verify the proposed optimum design processor. The numerical results of the model are conversed well and satisfied all constrains. This processor is a relatively simple method to carry out optimum design with consideration in global buckling, and is viable in practice with respect to structural design.