• Advances in Computational Design
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• v.5 no.1
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• pp.55-89
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• 2020

For the first time, an accurate analytical solution, based on coupled three-dimensional (3D) piezoelasticity equations, is presented for free vibration analysis of the angle-ply elastic and piezoelectric flat laminated panels under arbitrary boundary conditions. The present analytical solution is applicable to composite, sandwich and hybrid panels having arbitrary angle-ply lay-up, material properties, and boundary conditions. The modified Hamiltons principle approach has been applied to derive the weak form of governing equations where stresses, displacements, electric potential, and electric displacement field variables are considered as primary variables. Thereafter, multi-term multi-field extended Kantorovich approach (MMEKM) is employed to transform the governing equation into two sets of algebraic-ordinary differential equations (ODEs), one along in-plane (x) and other along the thickness (z) direction, respectively. These ODEs are solved in closed-form manner, which ensures the same order of accuracy for all the variables (stresses, displacements, and electric variables) by satisfying the boundary and continuity equations in exact manners. A robust algorithm is developed for extracting the natural frequencies and mode shapes. The numerical results are reported for various configurations such as elastic panels, sandwich panels and piezoelectric panels under different sets of boundary conditions. The effect of ply-angle and thickness to span ratio (s) on the dynamic behavior of the panels are also investigated. The presented 3D analytical solution will be helpful in the assessment of various 1D theories and numerical methods.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.6
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• pp.30-37
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• 1997

We present an efficient technique, bidirectioanl inertial maximum cost search technique, for th edetection and segmentation of circular shaped objects using the spatial information around the neighborhood of the boundary candidates. This technique searches boundary candidates using local pixdl information such as pixel value and its direction. And then to exclude pseudo-boundary caused by shadows or noises, the local contrast is defined between the clique of the boundary candidates and the cliques of the background. In order to effectively segment circular shaped boundary, the technique also uses the curvature based on trigonometirc function which determines circular shaped boundary segments. Since the proposed technique is applied to the pixel cliques instead of a pixel itself, it is proposed method can easily find out circular boundaries form iamges of the PCB containing circular shaped parts and the trees with round fruits compared to boundary detection by using the pixel information and the laplacian curvature.

• Tribology and Lubricants
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• v.11 no.2
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• pp.34-43
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• 1995

The boundary films formed in sliding on steel surfaces were characterized using various lubricants. The mechanism of boundary film formation and loss was investigated over a range of temperature. The thickness of the boundary films was monitored in-situ by an ellipsometer, and the composition of the films was analyzed by XPS. The performance of the lubricants is closely associated with boundary film forming ability. In order to achieve high load carrying capacity, a boundary film must be formed on the surface. Sliding is necessary to form the films and some time is also required. As temperature increases, chemical reactivity increases the film formation rate, while the film removal rate increases due to thg decrease of durability of the boundary film material. There is a balance between these two competing mechanisms and this balance is reflected in the boundary film thickness.

• Composites Research
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• v.16 no.5
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• pp.28-38
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• 2003

In this study, the analytical investigation of orthotropic rectangular plate is presented. The loaded edges are assumed to be simply supported and the unloaded edges could have elastically restrained boundary conditions including the extreme boundary condition such as simple, fixed, and free. Using the closed-form solutions, the buckling analyses of orthotropic plate with arbitrary boundary conditions are performed. Based on the data obtained by conducting numerical analysis, the simplified form of equation for finding the buckling coefficient of plate with elastically restrained boundary conditions at the unloaded edges is suggested as a function of aspect ratio, elastic restraint. and material properties of the plate. The results of buckling analyses by closed-form solution and simplified form of solution are compared for various orthotropic material properties. It is confirmed that the difference of results is less than 1.5%.

• Tribology and Lubricants
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• v.15 no.3
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• pp.248-256
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• 1999

Many tribological components in automobile engine undergo high load and sliding speed with thin film thickness. The lubrication characteristics of the components are regarded as ether hydrodynamic lubrication or boundary lubrication, whereas in a working cycle they actually have both characteristics. Many modem engine lubricants have various additives for better performance which make boundary film formation even under hydrodynamic lubrication regime. Conventional Reynolds equation with the viewpoints of continuum mechanics concerns only bulk viscosity of lubricant, which means that its simulation does not give insights on boundary lubrication characteristics. However, many additives of modern engine lubricant provide mixed modes of boundary lubrication characteristics and hydrodynamic lubrication. Especially, high molecular weight polymeric viscosity index improvers form boundary film on the solid surface and cause non-Newtonian fluid effect of shear thinning. This study has performed the investigation about journal bearing system with the mixed concepts of boundary lubrication and hydrodynamic lubrication which happen concurrently in many engine components under the condition of viscosity index improver added.

• Korean Journal of Computational Design and Engineering
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• v.5 no.3
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• pp.207-214
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• 2000

For last 20 years, a number of researches and developments on finite element mesh generation has been carried out and most of them are comported of node generation part and node generation part. However these algorithms are inefficient in mesh veneration process and difficult to control the shape of elements when comparing with the generation of nodes and elements concurrently. In this study, therefore, an algorithm it proposed to generate nodes and elements concurrently for various two-dimensional objects having multiple holes. Inner node generation is performed by choosing three consecutive boundary nodes and comparing them with other close boundary nodes. As soon as inner nodes are determined, element generation is conducted based on the comparison of the distances among the generated inner nodes, three consecutive boundary nodes and other close boundary nodes. the generated element nodes become new boundary nodes for further repeated process. The processes are repeated through out each region until three consecutive boundary nodes finally form a tirangular element.

• Fashion & Textile Research Journal
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• v.17 no.1
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• pp.11-21
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• 2015

This study analyzed the expressive phenomenon of a blurred boundary in fashion jewelry focused on the relationship between fashion jewelry and costume or fashion jewelry and body. The method of this study was to analyze recent documentaries about jewelry theories in regards to 607 cases of fashion jewelry design in fashion books, fashion magazines, fashion internet sites from 2000 to 2014. The results were: First, phenomenon of blurred boundary between fashion jewelry and costume was expressed in a see-through wear form made of luxury material (gold and diamond) or paste material, a similar form (like fashion accessories made of crystal, bids, and gold chain), an integration of fashion accessories and jewelry, and an attached jewelry on fashion accessories. It reflected a rearrangement of conventional relationships, a blurred relation of function and meaning, dissolution of jewelry form stereotypes, jewelry styling, a harmony of function and decoration, and an alteration to the central role of a fashion image. Second, the phenomenon of a blurred boundary between fashion jewelry and body was expressed in a body organ wrapping, body surface adhesion and sculptural jewelry based on body pose. It reflected a separation from conventional space of jewelry expression, a realization of mystery and fantastic, an expression of new body surface and a blurred boundaries of fashion jewelry and body art. Aesthetic characteristics were analyzed into metaphor and integration by separation from the conventional relationship of fashion jewelry and costume or fashion jewelry and body.

• Bulletin of the Society of Naval Architects of Korea
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• v.23 no.1
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• pp.13-22
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• 1986

Axisymmetric turbulent thick boundary layers on a rotating body of revolution are calculated numerically in the paper. Richardson number is introduced to the mixing length to take account of swirl effects on Reynolds stresses. Interactions of the boundary layer and the external potential flow are included by adding the displacement thickness of boundary layers on the original body. Pressure distributions on the body surface are estimated by integrating normal momentum equation across the boundary layer. A model is designed and tested in the wind tunnel. Mean velocities are measured. Through the present study, swirl effects on the thick axisymmetric boundary layer development are considerable in comparison with those of non-totating cases. Rotational motion generally increase boundary layer thickness, axial skin friction coefficients, and form drags. Circumferential flow can be reversed to induce negative skin friction when the section area is reduced.

• Journal of applied mathematics & informatics
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• v.13 no.1_2
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• pp.53-65
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• 2003

Here we present a study of small-amplitude, shallow water waves on sloping beds. The beds considered in this analysis are linear and quadratic in nature. First we start with stating the relevant governing equations and boundary conditions for the theory of water waves. Once the complete prescription of the water-wave problem is available based on some assumptions (like inviscid, irrotational flow), we normalize it by introducing a suitable set of non-dimensional variables and then we scale the variables with respect to the amplitude parameter. This helps us to characterize the various types of approximation. In the process, a summary of equations that represent different approximations of the water-wave problem is stated. All the relevant equations are presented in rectangular Cartesian coordinates. Then we derive the equations and boundary conditions for small-amplitude and shallow water waves. Two specific types of bed are considered for our calculations. One is a bed with constant slope and the other bed has a quadratic form of surface. These are solved by using separation of variables method.

• Coupled systems mechanics
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• v.4 no.1
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• pp.1-18
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• 2015

The state-based peridynamics is considered a nonlocal method in which the equations of motion utilize integral form as opposed to the partial differential equations in the classical continuum mechanics. As a result, the enforcement of boundary conditions in solid mechanics analyses cannot follow the standard way as in a classical continuum theory. In this paper, a new approach for the boundary condition enforcement in the state-based peridynamic formulation is presented. The new method is first formulated based on a convex kernel approximation to restore the Kronecker-delta property on the boundary in 1-D case. The convex kernel approximation is further localized near the boundary to meet the condition that recovers the correct boundary particle forces. The new formulation is extended to the two-dimensional problem and is shown to reserve the conservation of linear momentum and angular momentum. Three numerical benchmarks are provided to demonstrate the effectiveness and accuracy of the proposed approach.