• Steel and Composite Structures
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• v.39 no.4
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• pp.419-433
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• 2021

In composite structures, shear connectors are crucial components to resist the relative slip between the steel and concrete, and thereby to achieve the composite actions. In the service stage, composite structures are usually in elastic state, so the elastic stiffness of the shear connection is a quite important parameter in the structural analysis of composite structures. Nevertheless, the existing studies mainly focus on the load-slip relationship rather than the tangent stiffness at the initial elastic stage. Furthermore, when composite beams subjected to torque or local load, shear connections are affected by both tensile force and shear force. However, the stiffness of shear connections under combined effects appears not to have been discussed hitherto. This paper investigates the initial elastic stiffness of stud connections under combined effects of biaxial forces. The initial expression and the relevant parameters are obtained by establishing a simplified analytical model of the stud connection. Afterwards, parametric finite element analysis is performed to investigate the effects of the relevant factors, including the stud length, stud diameter, elastic modulus of concrete, elastic modulus of steel and volume ratio of reinforcement. The feasibility of the proposed modelling has been proved by comparing with sufficient experimental tests. Based on the analytical analysis and the extensive numerical simulations, design equations for predicting the initial elastic stiffness of stud connections are proposed. The comparison between the equations and the data of finite element models demonstrates that the equations are accurate enough to serve for engineering communities.

• Journal of the Korea Concrete Institute
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• v.25 no.4
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• pp.401-409
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• 2013

In the present study, numerical analysis was performed for hydrodynamic motion and structural performance on four different concrete floating structures, which have same cross-section but different length. The hydrodynamic analysis of floating structures is carried out using ANSYS AQWA with the different 34 wave load on regular wave period from three seconds to ten seconds in 35 m water depth. In order to evaluate structural performance of floating structures under the critical wave load which obtained from hydrodynamic analysis. The integrated analysis is also carried out through the mapping method, which can directly connect the wave-induced hydraulic pressure obtained form ANSYS AQWA to Finite Element Model in ANSYS Mechanical. As a results of this study, the hydrodynamic motion of floating structures is decreased as the length of structure increased. It means that the effect of wave-structure interaction is strongly dependent on the relationship between a wave period and a length of structure. Moreover, it is found that tension stress on bottom slab of floating structure is occurred by the critical wave load, the sectional force is not influenced by length of a structure.

• Physical Therapy Korea
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• v.6 no.1
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• pp.1-14
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• 1999

The quadriceps angle (Q angle) has been used to reflect the quadriceps muscle's force on the patella in the frontal plane. Previous investigations of the Q angle and it's relationship to knee disorders have yield equivocal results. The purpose of this study was to analyze the factors related to the Q angle and it's relation to other variables such as leg length, body weight, CTA (calcaneus to tibia angle), TOA (toe out angle), and pelvic width in normal subjects. The participants were 60 students (30 men and 30 women) who had no orthopedic and neurological impairments, aged from 20 to 29 years of age, with an average age of 22.1 years. Prior to participation, each subject was informed of the procedures of the experiment from a researcher and assistant researchers. The equipment used in this study were modified standard goniometer, ruler, marking pen, and Martin apparatus for pelvic width. In order to determine the statistical significance of the experiment, regression analysis, independent t-test, and Pearson correlation were used at the 0.05 level. The results were as follows: 1) It was found that the Q angle of women is greater than that of men's from both knees. 2) There was no significant difference between right and left quadriceps angle. 3) The Q angle decreased as the body weight (leg length) shifted from low to high. 4) It seems that factors related to the Q angle were body weight, CTA, and pelvic width, but there was no significant difference at the 0.05 level.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1061-1064
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• 2008

Shear connectors have a finite slip capacity because of the mechanism by which they transfer the shear between UHPFRC and NC elements. At high degree of shear connection, non-linear analysis techniques are required to allow for compressive plasticity and tensile cracking behaviour of the elements. As with all non-linear problems, a closed form solution is difficult to find. A Modified Shooting Method Technique is developed here for non-linear analysis of UHPFRC/concrete composite. The initial effective moment is derived according to the prestressing force. The composite structure is divided into small segments which length is much less than the length of the structure and it can be assumed that the forces and displacements within each segment are constant. An equivalent analysis in composite girders would be to fix the slip strain in each segment and develop a moment curvature relationship for this slip strain in each segment. Additive forces and moment analysis on each section of the segments are analyzed by MSMT. Finally the ultimate slippage of the interface can be evaluated by the MSMT model. This paper presents a nonlinear analysis method for limited slip capacity of UHPFRC-NC interface.

• ALGAE
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• v.37 no.1
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• pp.63-74
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• 2022

Perennial stipitate kelps are globally distributed and individual species can inhabit broad latitudinal ranges, expressing notably longevous persistence. Despite the foundational role kelps provide to their communities, little is known about the variability in persistence of the stipitate kelps at local spatial scales. We studied the population persistence of Eisenia arborea, a heat- and wave force-tolerant perennial stipitate kelp with a distributional range extending from British Columbia to south of the range limit of all other northeast Pacific kelps, in Baja California Sur, Mexico. Persistence characteristics for E. arborea among sites were compared and used to test the hypothesis that stand persistence varied at local spatial scales around Isla Natividad, a Pacific island off the Baja California peninsula with documented spatiotemporal environmental heterogeneity. Collected individuals around the island were "aged" using the previously validated age estimation technique of counting annual cortical dark rings. After detecting no significant differences among sites in the covariation between estimated ages for collected individuals and stipe length, we utilized in-situ population-level stipe length measurements to more rapidly predict age structures within six stands around the island. Predicted age structures, and associated stand densities, revealed persistence characteristics and density varied at local scales and a strong positive relationship existed between stand density and stand mean and maximum ages. We speculate that stands responded differently to deterministic influences (e.g., the 2014-2016 marine heatwave and / or competition with Macrocystis) resulting in heterogenous local persistence of this foundation species.

• Journal of Korean Association for Spatial Structures
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• v.24 no.1
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• pp.29-36
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• 2024

The paper presents the experimental investigation of RC beams retrofitted with Textile Reinforced Mortar (TRM), featuring enhanced bond capacity. Anchoring systems, including an extension of retrofitting length and the use of chemical anchors, are newly employed to improve the structural performance of the RC beam retrofitted with TRM. For the experimental investigation, a total of seven shear-critical RC beams, with and without stirrups, were designed and constructed. The structural behaviors of specimens retrofitted with the proposed TRM methods were compared to those of non-retrofitted specimens or specimens strengthened with conventional TRM methods. Crack pattern, force-displacement relationship, and absorbed energy were evaluated for each specimen. The experimental results indicate a significant improvement in the shear capacity of the RC beam with the proposed retrofitting method. Therefore, it is concluded that the application of an extended retrofitting length and chemical anchors to the TRM retrofitting method can effectively enhance the bond capacity of TRM, thereby improving the shear performance of RC beams.

• Food Science of Animal Resources
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• v.40 no.6
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• pp.957-968
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• 2020

The influence of muscle architecture on muscle fiber characteristics and meat quality has not been fully elucidated. In the present study, muscle fiber characteristics on the chop surface of pork loin (M. longissimus thoracis et lumborum, LTL), pennation angle degree, and meat quality were evaluated to understand the pork LTL architecture and its relationship with the loin chop quality. Muscle fiber pennation degree ranged from 51.33° to 69.00°, resulting in an ellipse-shaped muscle fiber on the surface of pork loin chop. The cross-sectional area (CSA) on the sections cut vertical to the muscle length (M-Vertical) was considerably larger (p<0.05) than that on the sections cut vertical to the muscle fiber orientation (F-Vertical) regardless of the fiber type. Pennation angle is positively correlated with CSAs of F-Vertical (p<0.05) and with Warner-Bratzler shear force (r=0.53, p<0.01). Besides the shear force, lightness and pH were positively correlated with the fiber composition and CSA of IIX fiber (p<0.05); however, the redness, yellowness, drip loss, and cooking loss were not correlated with the pennation angle and muscle fiber characteristics on the chop surface (p>0.05). These observations might help us in better understanding pork loin architecture and the relationship between the pennation angle, muscle fiber characteristics, and meat quality of pork loin chop.

• 연구논문집
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• s.34
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• pp.101-112
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• 2004

In order to analyze the motion errors of the aerostatic stage, it is necessary to consider the influence of the moment variation occurredinside the pads. In this paper, a motion error anaysis method utilizing the transfer functions on the reaction force and moment is proposed, and general characteristics of the transfer functions are discussed. Calculated motion errors by the proposed method show good agreement with the ones calculated by Multi Pad Method, which is considered the entire table as an analysis object. Also, by the introduction of the transfer function of motion errors, which represent the relationship between the spatial frequency components of the rail form error and motion errors, motional characteristics of the porous aerostatic stage can be generalized. In detail, the influence of the spatial frequencies is analyzed quantatively, and the patterns of the insensitive frequencies which almost do not affect the linear motion error or angular motion error according to the rail length ratio and the number of the pad are verified. The relationship between the moment variation occurred inside the pads and the motion errors is also verified together.

• Earthquakes and Structures
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• v.15 no.4
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• pp.419-429
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• 2018

The seismic vulnerability analysis of multi-span bridges can be based on the response of the piers, provided that deck, bearings and foundations remain elastic. The lateral response of an RC bridge pier can be affected by different mechanisms (i.e., flexure, shear, lap-splice or buckling of the longitudinal reinforcement bars, second order effects). In the literature, simplified formulations are available for mechanisms different from the flexure. On the other hand, the flexural response is usually calculated with a numerically-based Moment-Curvature diagram of the base section and equivalent plastic hinge length. The goal of this paper is to propose a simplified analytical solution to obtain the Moment-Curvature relationship for hollow circular RC sections. This based on calibrated polynomials, fitted against a database comprising 720 numerical Moment-Curvature analyses. The section capacity curve is defined through the position of 6 characteristic points and they are based on four input parameters: void ratio of the hollow section, axial force ratio, longitudinal reinforcement ratio, transversal reinforcement ratio. A case study RC bridge pier is assessed with the proposed solution and the results are compared to a refined numerical FEM analysis, showing good match.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.143-143
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• 2008

Nanowires are promising options for building nanoscale electronic structures coming from high conductivity of nanowires. In particular, Deoxyribonucleic acid (DNA), which is structurally nanowire, can obtain highly ordered electronic components for nanocircuitry and/or nanodevices because of its very flexible length controllability, nanometer-size diameter, about 2 nm, and self-assembling properties. In this work, we used the method to form DNA-Nanowires (NWs) by using chemical treatment on Silicon (Si) surface, and Aminopropyl-triethoxysilane (APTES) was used as inducer of DNA sequence to modify the characteristics of Si surface. Moreover, we performed tilting technique to align DNA by the direction of flow of DNA solution. We investigated the assembly process between DNA molecules and APTES - coated Si surface according to the APTES concentration, from $1.2{\mu}\ell$ to $120{\mu}\ell$. Atomic Force Microscopy (AFM) images showed the combination rate of DNA molecules by the change of APTES concentration. As APTES concentration becomes thicker, aggregation of DNA molecules occurs, and this makes a kind of DNA networks. In this respect, we confirmed that there's a positive relationship between the concentration of APTES and the formation rate of DNA nanowires. Since there have been lots of research preceded to utilize DNA nanowires as template, so by using this positive relationship with proper alignment technique, realization of nano electronic devices with DNA nanowires might be feasible.