• Journal of Korean Society of Steel Construction
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• v.15 no.2
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• pp.97-107
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• 2003

To obtain a more accurate response from larninated composite structures, the effect of transverse shear deformation, transverse normal strain/stress, and nonlinear variation of in-plane displacements vis-$\\grave{a}$-vis the thickness coordinate should be considered in the analysis. The improved higher-order theory was used to determine the critical buckling load and natural frequencies of laminated composite structures. Solutions of simply supported laminated composite plates and sandwiches were obtained in closed form using Navier's technique, with the results compared with calculated results using the first order and other higher-order theories. Numerical results were presented for fiber-reinforced laminates, which show the effects of ply orientation, number of layers, side-toithickness ratio, and aspects ratio.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.525-532
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• 2014

In this study, practical design method of coupling beams is proposed. The member forces varies according to the location of the members and the members at 25%~40% of building height shows large member forces. The 100mm increase of wall thickness causes 3~4% variation of member forces and the 100MPa increase of concrete strength decrease approximately 3% of member forces. The required strength of coupling beams is twice the resistant strength and 80% reduction of coupling beam stiffness is necessary to fulfill the design criteria. The stiffness reduction of coupling beams is not necessary over the entire stories and the strength reduction range can be estimated considering design requirements.

• Fashion & Textile Research Journal
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• v.14 no.4
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• pp.641-647
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• 2012

This study investigates the sound properties of fabric frictional sound (SPL, ${\Delta}L$, ${\Delta}f$) according to the film type of PTFE laminated vapor-permeable water-repellent fabrics in order to understand the relationship between SPL and the basic properties of fabrics such as layer, yarn type, and thickness of fiber. This study accesses their mechanical properties and determines how to control them to minimize SPL. Eight PTFE laminated water-repellent fabrics, composed of four different film types (A, B, C, D) and with two different fabrics, were used as test specimens. Frictional sounds generated at 1.21m/s were recorded by using a fabric sound generator and SPLs were analyzed through Fast Fourier Transformation (FFT). The mechanical properties of fabrics were measured by KES-FB. The SPL value was lowest at 74.4dB in film type A and highest as 85.5dB in type D. Based on ANOVA and post-hoc test, specimens were classified into less Loud Group (A, B) and Loud Group (C, D). It was shown that SPL was lower when 2 layer (instead of 3 layer), filament yarn than staple, and thin fiber than thick were used. In Group I, shearing properties (G, 2HG5), geometrical roughness (SMD), compressional properties (LC, RC) and weight (W) showed high correlation with SPL however, elongation (EM) and shear stiffness (G) did with SPL in Group II.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.10
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• pp.1452-1458
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• 2004

An experiment was conducted to examine the effects of sex and market weight on performance, carcass characteristics and pork quality. A total of 224 crossbred pigs (initially 26.64 kg BW) were allotted in a $2{\times}4$ factorial arrangement in a randomized complete block (RCB) design. The variables were sex (gilts and barrows) and different market weights (100, 110, 120 and 130 kg). Average daily gain (ADG) and average daily feed intake (ADFI) were significantly higher (p<0.01) in barrows than gilts, ADFI and feed conversion ratio (FCR) increased as body weight increased (p<0.05). Gender differences were observed in carcass characteristics. Backfat thickness and drip loss were greater in barrows (p<0.01), while loin eye area (p<0.01), flavor score (p<0.05) and lean content (p<0.001) were higher in gilts. Carcass grade and water holding capacity were the highest in 110 kg market weight pigs. The 100 kg arket weight pigs showed lower juiciness, tenderness, shear forces and total palatability than the other market weights (p<0.01). Hunter values (L*, a* and b*) were increased as market weight increased (p<0.05). Hunter a* value was greater in gilts (p<0.01) but L* value and b* value were not affected by sex of pigs. Net profit [(carcass weight${\times}$price by carcass grade)-(total feed cost+cost of purchased pig)] was higher in gilts than barrows (p<0.01), and was higher (p<0.05) in the pigs marketed at 110 and 120 kg market weight compared with 100 kg market weight. These results demonstrated that gilts showed higher carcass characteristics, pork quality, feed cost per kg body weight gain and net profit compared with barrows. Moreover, 110 or 120 kg body weight would be the recommended market weight based on pork quality and net profit for swine producers.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.5 s.51
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• pp.73-83
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• 2006

The purpose of this study is to investigate the seismic behavior of reinforced concrete pier walls under cyclic out-of-plane loading and to develop improved seismic design criteria. The accuracy and objectivity of the assessment process can be enhanced by using a sophisticated nonlinear finite element analysis program. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. A 4-node flat shell element with drilling rotational stiffness is used for spatial discretization. The layered approach is used to discretize the behavior of concrete and reinforcement through the thickness. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The method is verified a useful tool to assess the seismic performance of reinforced concrete pier walls subjected to cyclic out-of-plane load through comparing with reliable experimental results.

• Structural Engineering and Mechanics
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• v.73 no.2
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• pp.191-207
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• 2020

This study aims at investigating the size-dependent free vibration of porous nanoplates when exposed to hygrothermal environment and rested on Kerr foundation. Based on the modified power-law model, material properties of porous functionally graded (FG) nanoplates are supposed to change continuously along the thickness direction. The generalized nonlocal strain gradient elasticity theory incorporating three scale factors (i.e. lower- and higher-order nonlocal parameters, strain gradient length scale parameter), is employed to expand the assumption of second shear deformation theory (SSDT) for considering the small size effect on plates. The governing equations are obtained based on Hamilton's principle and then the equations are solved using an analytical method. The elastic Kerr foundation, as a highly effected foundation type, is adopted to capture the foundation effects. Three different patterns of porosity (namely, even, uneven and logarithmic-uneven porosities) are also considered to fill some gaps of porosity impact. A comparative study is given by using various structural models to show the effect of material composition, porosity distribution, temperature and moisture differences, size dependency and elastic Kerr foundation on the size-dependent free vibration of porous nanoplates. Results show a significant change in higher-order frequencies due to small scale parameters, which could be due to the size effect mechanisms. Furthermore, Porosities inside of the material properties often present a stiffness softening effect on the vibration frequency of FG nanoplates.

• Structural Engineering and Mechanics
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• v.75 no.3
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• pp.401-414
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• 2020

Unlike the existing truss models for shear and torsion analysis, in this study, the torsional capacities of reinforced concrete (RC) members were estimated by introducing multi-potential capacity criteria that considered the aggregate interlock, concrete crushing, and spalling of concrete cover. The smeared truss model based on the fixed-angle theory was utilized to obtain the torsional behavior of reinforced concrete member, and the multi-potential capacity criteria were then applied to draw the capacity of the member. In addition, to avoid any iterative calculation in the existing torsional behavior model, a simple strength model was suggested that considers key variables, such as the effective thickness of torsional member, principal stress angle, and strain effect that reduces the resistance of concrete due to large longitudinal tensile strain. The proposed multi-potential capacity concept and the simple strength model were verified by comparing with test results collected from the literature. The study found that the multi-potential capacity could estimate in a rational manner not only the torsional strength but also the failure mode of RC members subjected to torsional moment, by reflecting the reinforcing index in both transverse and longitudinal directions, as well as the sectional and material properties of RC members.

• Steel and Composite Structures
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• v.35 no.5
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• pp.671-685
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• 2020

This manuscript presents impacts of gradation of material functions and axial load functions on critical buckling loads and mode shapes of functionally graded (FG) thin and thick beams by using higher order shear deformation theory, for the first time. Volume fractions of metal and ceramic materials are assumed to be distributed through a beam thickness by both sigmoid law and symmetric power functions. Ceramic-metal-ceramic (CMC) and metal-ceramic-metal (MCM) symmetric distributions are proposed relative to mid-plane of the beam structure. The axial compressive load is depicted by constant, linear, and parabolic continuous functions through the axial direction. The equilibrium governing equations are derived by using Hamilton's principles. Numerical differential quadrature method (DQM) is developed to discretize the spatial domain and covert the governing variable coefficients differential equations and boundary conditions to system of algebraic equations. Algebraic equations are formed as a generalized matrix eigenvalue problem, that will be solved to get eigenvalues (buckling loads) and eigenvectors (mode shapes). The proposed model is verified with respectable published work. Numerical results depict influences of gradation function, gradation parameter, axial load function, slenderness ratio and boundary conditions on critical buckling loads and mode-shapes of FG beam structure. It is found that gradation types have different effects on the critical buckling. The proposed model can be effective in analysis and design of structure beam element subject to distributed axial compressive load, such as, spacecraft, nuclear structure, and naval structure.

• Journal of the Korean Geotechnical Society
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• v.32 no.7
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• pp.35-45
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• 2016

Estimation of vertical bearing capacity is critical in the design of bucket foundation used to support offshore structure. Empirical formula and closed form solutions for bucket foundations in uniform sand or clay profiles have been extensively studied. However, the vertical bearing capacity of bucket foundations in alternating layers of sand overlying clay is not well defined. We performed a series of two-dimensional axisymmetric finite element analyses on bucket foundations in sand overlying clay soil, using elasto-plastic soil model. The load transfer mechanism is investigated for various conditions. Performing the parametric study for the friction angles, undrained shear strengths, thickness of sand layer, and aspect ratios of foundation, we present the predictive charts for determining the vertical bearing capacities of bucket foundations in sand overlying clay layer. In addition, after comparing with the finite element analysis results, it is found that linear interpolation between the design charts give acceptable values in these ranges of parameters.

• Journal of the Korean Geosynthetics Society
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• v.14 no.4
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• pp.129-137
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• 2015

Recently, offshore wind farms are increasingly expected, because there are huge resource and large site in offshore. Jeju island has optimum condition for constructing a wind energy farm. Unlike the mainland, Jeju island has stratified structure distribution between rock layers sediments due to volcanic activation. In these case, it can be occur engineering problems in whole structures as well as the safety of foundation as the thickness and distribution of sediment under top rock layer can not support sufficiently the structure. One of the most obvious applications of the pressuremeter test is the solution of the problem of laterally loaded piles. A hyperbolic non-linear p-y criterion for rock is developed in this study that can be used in LPILE program, to predict the deflection, moment, and shear reponses of a shaft under the applied lateral loads. Finally, a comparison between the predicted and measured response at two different sites is shown to give an idea of the accuracy of the IFP method.