• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.261-264
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• 2006

Deformability of RC members in shear after flexural yielding is limited and controlled by governing failure modes and material strength. Shear strength of members in D-regions has been explained by a direct load path (direct strut or arch action) and indirect load path (fan action or truss action). Indirect load path including truss action and fan action rely on bond along tension ties. Generally, superposition of two actions results in total shear strength when shear failure modes control. The ultimate deformation depends on controlling failure modes and thereby, their force transfer patterns. Proposed models are capable of explaining of limited deformability of RC members in D-regions.

• Steel and Composite Structures
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• v.35 no.5
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• pp.659-670
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• 2020

This paper proposes the use of a porous core between layers of laminated composite plates to examine its effect on the natural frequencies of the resulted porous laminated composite sandwich plate (PLCSP) resting on a two-parameter elastic foundation. Moreover, it has been suggested that the dispersion of porosity has two different functionally graded (FG) patterns which are compared with a uniformly dispersed (UD) profile to find their best vibrational efficiency in the proposed PLCSPs. In FG patterns, two types of dispersions, including symmetric (FG-S) and asymmetric (FG-A) patterns have been considered. To derive the governing Eigen value equation of such structures, the first order shear deformation theory (FSDT) of plates has been employed. Accordingly, a finite element method (FEM) is developed to solve the derived Eigen value equation. Using the mentioned theory and method, the effects of porosity parameters, fiber orientation of laminated composite, geometrical dimensions, boundary conditions and elastic foundation on the natural frequencies of the proposed PLCSPs have been studied. It is observed that embedding porosity in core layer leads to a significant improvement in the natural frequencies of PLCSPs. Moreover, the natural frequencies of PLCSPs with FG porous core are higher than those with UD porous core.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.3
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• pp.181-187
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• 2014

Micro patterns are used to maximize the performance and efficiency of the product in many industries such as energy, display, printing, biology, etc. Nowadays, the fabrication technology for micro patterns has been developed in various ways such as photolithography, laser machining, electrical discharge machining and mechanical machining. Recently, mechanical machining the size of smaller than 1 micrometer could be tried, because the technology related to the machining was developed brilliantly. This paper shows the experiments using cutting processes in order to fabricate the micro pattern. Micro patterns of the size of several micrometers were machined by the diamond tools of two different shape, the deformation and generation of burr were investigated.

• Steel and Composite Structures
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• v.29 no.5
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• pp.569-578
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• 2018

This paper aims to investigate the transient vibration behavior of functionally graded carbon nanotube (FG-CNT) reinforced nanocomposite plate resting on Pasternak foundation under pulse excitation. The plate is considered to be composed of matrix material and multi-walled carbon nanotubes (MWCNTs) with distribution as per the functional grading concept. The functionally graded distribution patterns in nanocomposite plate are explained more appropriately with the layer-wise variation of carbon nanotubes weight fraction in the thickness coordinate. The layers are stacked up in such a way that it yields uniform and three other types of distribution patterns. The effective material properties of each layer in nanocomposite plate are obtained by modified Halpin-Tsai model and rule of mixtures. The governing equations of an illustrative case of simply-supported nanocomposite plate resting on the Pasternak foundation are derived from third order shear deformation theory and Navier's solution technique. A converge transient response of nanocompiste plate under uniformly distributed load with triangular pulse is obtained by varying number of layer in thickness direction. The validity and accuracy of the present model is also checked by comparing the results with those available in literature for isotropic case. Then, numerical examples are presented to highlight the effects of distribution patterns, foundation stiffness, carbon nanotube parameters and plate aspect ratio on the central deflection response. The results are extended with the consideration of proportional damping in the system and found that nanocomposite plate with distribution III have minimum settling time as compared to the other distributions.

• Korean Journal of Human Ecology
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• v.21 no.3
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• pp.551-565
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• 2012

The primary goal of this study was to provide a systematic methodology of utilizing 3D technology for tight-fit performance sportswear using information of skin deformation in various posture. Technical tools used in this study are Cyberware whole body scanner, RapidForm2004, 2C-AN 3D pattern development program, and YukaCAD. Analysis of the 3D skin deformation while knee joint was bent from $0^{\circ}$ to $60^{\circ}$ revealed that the length of dermatomes L4 was remained consistent during knee bending. Therefore, L4 was chosen as a major cutting line. To develop a highly ergonomic pattern, replicas of static and dynamic postures were developed and integrated using two methods, one is morphing method (Sqirlz Morph), and the other is AutoCAD. Experimental tight-fit garments called 'Derm-Mov Pattern' was designed using dematomes L4, L2, and inner line under knee and compared with four other patterns. As results, AutoCAD was appropriate as a integrating method of various postures. In wear test, 'Derm-Mov Pattern' was rated high (p < .001), in terms of pressure comfort especially around front crotch area. However, wear sensation was not signipicantly different in other area due to highly extensible property of materials. Pressure distribution was relatively even in these experimental garments.

• Composites Research
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• v.16 no.4
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• pp.29-35
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• 2003

In this paper. various tow parameters such as equivalent tow thickness, amplitude of longitudinal tow and tow intervals were investigated and compared with each other by using microscopic observation to find out the exact deformation patterns between both directions of the fabric structure(Longitudinal and Transverse Directions). And those observation results were compared with bias extension. biaxial tests results with dry fabric which has the same tow structure as the draped helmet materials and also compared with prepreg specimen which is cured by autoclave moulding without vacuum and pressure condition. Specimens for the observation were taken from draped helmet which is made of fabric composite(Five Harness Satin Weave). From the observation results, it was found that there are different deformation pattern between tow directions and effect of geometric condition on the deformation of the fabric materials during draping process was verified.

• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.4
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• pp.199-206
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• 2004

Construction of a large offshore structure in coastal area may cause serious morphological changes for a wide region ranging from shoreline to offshore behind the structure. Shin et at. [2000] and Shin and Hong [2004] identified the sediment transport patterns behind the large offshore structure through a series of three dimensional movable bed experiments. In present study, a hybrid three dimensional beach deformation model was suggested based on those sediment transport mechanisms revealed by experimental results of the preceding studies. The model was verified by the results of the three dimensional moveable bed experiments and they agreed well not only in reappeared tombolo in shoreline side but also in the erosion and deposition region behind offshore structure. In addition, the model was applied to real beach deformation problem, which was occurred by construction of artificial offshore islands, and it validates the applicability of the model.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.51-58
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• 2020

The purpose of this study is to investigate experimentally the material strength and tensile deformation behavior of highly ductile high-strength cement composites reinforced by synthetic fibers. Materials and mixture proportions were designed to make composites with a strength level of 80 MPa in compression. Two kinds of polyethylene fibers with different properties were employed as reinforcing fibers. A series of experiments on density, compressive strength, and deformation performance was performed. Experimental results showed that the tensile behavior and cracking patterns of cement composite strongly depends on the types of reinforcing fibers. It was also demonstrated that the cement composite with a compressive strength of 77.7 MPa and a tensile strain capacity of 7.9% can be manufactured by using a proper polyethylene fiber.

• Steel and Composite Structures
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• v.29 no.4
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• pp.545-555
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• 2018

This study aimed to investigate the flexural behavior of precast concrete (PC) wall - steel shoe composite assemblies with various dry connection details at mid-span. Flexural tests were performed for five scenarios. Test parameters included the width of test specimens, arrangement of steel shoe connectors, and use of structural adhesive or waterproof tape at the mid-span joint. The test results showed that the PC wall - steel shoe composite assemblies joined at mid-span showed flexural damage patterns combined with rotational deformation, and the structural performance was satisfactory regardless of the arrangement of steel shoe connectors. Considering the two deformation components (flexural deformation by bending and rotational deformation due to joint opening), a theoretical model was proposed to analyze flexural strength and joint opening, and the simple model gave good predictions with acceptable accuracy.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.3
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• pp.255-280
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• 2024

If there are concerns about the stability of segment lining due to section deficiency or large deformation in shield TBM tunnel, reinforcement can be done through ground grouting outside the tunnel or by using steel plate reinforcement, ring beam reinforcement, or inner double layer lining inside the tunnel. Traditional analyses of shield TBM tunnels have been conducted using a continuum method that does not consider the segmented nature of segment lining. This study investigates the reinforcement mechanism for double layer reinforced sections with internal steel linings. By improving the modeling of segment lining, this study applies Break-joint mode (BJM), which considers the segmented characteristics of segment lining, to analyze the deformation characteristics of double layer reinforced sections. The results indicate that the existing concrete segment lining functioned similarly to ground reinforcement around the tunnel, rather than distribution the load. In general, both the BJM model considering the segmentation of segment lining and the continuum rigid method were similar deformation shapes and stress distributions of the lining under load. However, in terms of deformation, when the load strength exceeded the threshold, the deformation patterns of the two models differed.