• Journal of Korean Society of Steel Construction
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• v.10 no.1 s.34
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• pp.11-24
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• 1998

The composite sandwich plate is constructed by combining two laminated facings with high strength and a thick core of light weight material. The governing equations for the analysis of bending of simply supported sandwich plates with laminated facings are derived and analysed using the analytical method including the local shear deformations. The accuracy of the approach is ascertained by comparing solutions from the sandwich plate theory with composite facings to the laminate plate theory. Since the present analysis considers the bending stiffness of the core and also the transverse shear deformations of the laminated facings, it is expected that the analysis is capable to analyze the general anisotropic laminated plates with global shear deformations.

• Design & Manufacturing
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• v.12 no.3
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• pp.42-47
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• 2018

Recently, in the surge of global environmental issues, there has been a great attention to lightweight materials in purpose of saving energy. Magnesium alloys not only have low specific gravity, and superb specific stiffness, but are also excellent in blocking vibrations and electromagnetic waves. So demand for this material is getting bigger rapidly throughout the industry. In this study, we examined the improvement of formability of magnesium alloy AZ31 material in warm working. Drawing, bending and shearing process were carried out by varying the forming temperature and the forming speed, and the influence of the variables on each process was studied. In the experiments, the high forming temperature and low forming speed results in high formability in the drawing process and the bending process. In the shearing process, as the forming temperature increases, the length of the fracture decreases.

• Smart Structures and Systems
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• v.19 no.2
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• pp.115-126
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• 2017

In this paper, size dependent bending and free flexural vibration behaviors of functionally graded (FG) nanobeams are investigated using a nonlocal quasi-3D theory in which both shear deformation and thickness stretching effects are introduced. The nonlocal elastic behavior is described by the differential constitutive model of Eringen, which enables the present model to become effective in the analysis and design of nanostructures. The present theory incorporates the length scale parameter (nonlocal parameter) which can capture the small scale effect, and furthermore accounts for both shear deformation and thickness stretching effects by virtue of a hyperbolic variation of all displacements through the thickness without using shear correction factor. The material properties of FG nanobeams are assumed to vary through the thickness according to a power law. The neutral surface position for such FG nanobeams is determined and the present theory based on exact neutral surface position is employed here. The governing equations are derived using the principal of minimum total potential energy. The effects of nonlocal parameter, aspect ratio and various material compositions on the static and dynamic responses of the FG nanobeam are discussed in detail. A detailed numerical study is carried out to examine the effect of material gradient index, the nonlocal parameter, the beam aspect ratio on the global response of the FG nanobeam. These findings are important in mechanical design considerations of devices that use carbon nanotubes.

• Journal of the Korean Society of Physical Medicine
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• v.5 no.3
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• pp.363-373
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• 2010

Purpose : The purpose of this study was to compare differences in thoracolumbar ranges of motions by comparing ratios among 4 type diagnosis for patient with chronic low back pain. Methods : The subjects were 58 chronic low back pain patients. A motion analysis program (Global Postural System) was used after photography for posture measurement. To analyze differences in mobility percentages and ratios of thoracolumbar ranges of motion, one-way ANOVA was used. Results : Regional difference spinal posture and movement were found to diagnosis patients with chronic low back pain. Comparison of thoracolumbar ranges of motion revealed significant differences in the thoracic region during forward-bending of the trunk (p<.05). In the upper thoracic region, the herniated intervertebral lumbar disc (HILD) group was significantly larger than the spinal stenosis/herniated intervertebral lumbar disc (SS/HILD) group (p<.05). In the lower thoracic region, chronic sprains (CS) were significantly greater than in the spinal stenosis (SS) group and in the (SS/HJLD) group (p<.05). Comparative analysis of thoracic/lumbar mobility ratio showed the CS group's ratio during forward bending was largest: 1.66, while the HILD group's ratio was smallest: 84 a significant difference between the two groups (p<.01). Diagnosis was not associated with difference in thoracolumbar backward-bending range of motion (p>.05). Conclusion : Theses results indicate the clinical efficacy of diagnosing for chronic low back pain by evaluating spinal mobility.

• Journal of the Korean Wood Science and Technology
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• v.37 no.4
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• pp.300-309
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• 2009

The effective utilization of wood structure is encouraged to preserve natural resources and the global environment. Long-span and large-scale structures are preferred to promote demand for wood. This study attempts to develop new Fire-resistance Composite Material composed of Structural steel and Structural glued laminated timber for long-span and large-scale structures. Prior to take a fire-resistance test, compare properties of bending strength with Composite material composed of Structural steel and Structural glued laminated timber, structural steel and structural provides the stability of the structure, but the structural glued laminated timber has high value elasticity of bending. Using the Composite material will improve structural stability and Eco-friend construction environment.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.6
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• pp.897-906
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• 2017

Projection Mapping, also known as Spatial Augmented Reality(SAR) has attracted much attention recently and used for many division, which can augment physical objects with projected various virtual replications. However, conventional approaches towards projection mapping have faced some limitations. Target objects' geometric transformation property does not considered, and movements of flexible objects-like paper are hard to handle, such as folding and bending as natural interaction. Also, precise registration and tracking has been a cumbersome process in the past. While there have been many researches on Projection Mapping on static objects, dynamic projection mapping that can keep tracking of a moving flexible target and aligning the projection at interactive level is still a challenge. Therefore, this paper propose a new method using Unity3D and ARToolkit for high-speed robust tracking and dynamic projection mapping onto non-rigid deforming objects rapidly and interactively. The method consists of four stages, forming cubic bezier surface, process of rendering transformation values, multiple marker recognition and tracking, and webcam real time-lapse imaging. Users can fold, curve, bend and twist to make interaction. This method can achieve three high-quality results. First, the system can detect the strong deformation of objects. Second, it reduces the occlusion error which reduces the misalignment between the target object and the projected video. Lastly, the accuracy and the robustness of this method can make result values to be projected exactly onto the target object in real-time with high-speed and precise transformation tracking.

• Transactions of the KSME C: Technology and Education
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• v.3 no.1
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• pp.37-44
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• 2015

In this paper dynamic deformation of lower hinge of refrigerator is simulated using dynamic finite element analysis while refrigerator is being dropped. The flow stress curves considering velocity dependency of hinge and lower packing material are determined through bending test and compression test at several dropping speeds. The determined material properties and flow stress from reverse engineering were used as input data for refrigerator's drop test using a dynamic finite element analysis software LS-DYNA. Additionally the result between CAE and 3D deformation measurement from real refrigerator drop test are compared and the result shows that the proposed analysis model is very useful to design lower hinge and lower packing endurable to the impulsive drop impact.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.4
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• pp.1-8
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• 2003

Thermo-mechanical behavior of a ceramic ball grid array (CBGA) package assembly are characterized by high sensitive moire interferometry. Moir fringe patterns are recorded and analyzed at various temperatures in a temperature cycle. Thermal-history dependent analyses of global and local deformations are presented, and bending deformation (warpage) of the package and shear strain in the rightmost solder ball are discussed. A significant non-linear global behavior is documented due to stress relaxation at high temperature. Analysis of the solder interconnections reveals that inelastic deformation accumulates on only eutectic solder fillet region at high temperatures.

• Steel and Composite Structures
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• v.7 no.1
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• pp.53-70
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• 2007

This paper presents a analysis of the problem of optimal design of the beams with two I-type cross section shapes. These types of beams are simply supported and subject to pure bending. The strength and stability conditions were formulated and analytically solved in the form of mathematical equations. Both global and selected types of local stability forms were taken into account. The optimization problem was defined as bicriteria. The cross section area of the beam is the first objective function, while the deflection of the beam is the second. The geometric parameters of cross section were selected as the design variables. The set of constraints includes global and local stability conditions, the strength condition, and technological and constructional requirements in the form of geometric relations. The optimization problem was formulated and solved with the help of the Pareto concept of optimality. During the numerical calculations a set of optimal compromise solutions was generated. The numerical procedures include discrete and continuous sets of the design variables. Results of numerical analysis are presented in the form of tables, cross section outlines and diagrams. Results are discussed at the end of the work. These results may be useful for designers in optimal designing of thin-walled beams, increasing information required in the decision-making procedure.

• Steel and Composite Structures
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• v.11 no.1
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• pp.1-19
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• 2011

The introduction of the Eurocodes makes plastic design criteria available also for composite bridges, leading to more economical solutions compared with previous elastic design rules. Particularly for refurbishment old bridges with higher actual traffic loads, up to date outside the scope of the Eurocodes, strengthening should therefore be avoidable or at least be necessary only to a minor extent. For bridges with smaller spans and compact cross sections, the plastic load bearing capacity is clearly justified. In this work, however, the focus is placed on long span continuous composite bridges with deep, longitudinally stiffened girders, susceptible to local buckling. In a first step, the elastic - plastic cross section capacity of the main girder in bending is studied as an isolated case, based on high preloads acting on the steel girder only, due to the common assembling procedure without scaffolding. In a second step, the effects on the whole structure are studied, because utilising the plastic section capacity at midspan leads to a redistribution of internal forces to the supports. Based on the comprehensive study of an old, actual strengthened composite bridge, some limitations for plastic design are identified. Moreover, fully plastic design will sometimes need additional global analysis. Practical recommendations are given for design purposes.