• The Journal of the Korea Contents Association
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• v.18 no.1
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• pp.441-451
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• 2018

The main point of this study is to use the principle of Coriolis force and the sense of fingertips to scratch the surface of the wall by high-speed rotation (RPM) to push the texture of the stripe from the inside to the outer wall, and to express the beautiful, dynamic and distinctive outer wall texture that is diversified by Coriolis force (centrifugal force). This is designated as Coriolis force technique. In addition, instead of the traditional flat bottom foot onggi molding technique, a new type of flat bottom foot that uses the electric wheel to push the cylinder from inside to out to expand the outer wall and to spread the bottom of foot flatly. The purpose of this study is to create a modernized, distinctive, new interior work by fusing these techniques.

• Earthquakes and Structures
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• v.26 no.6
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• pp.489-499
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• 2024

Infill masonry walls are vulnerable to lateral loads, including seismic, wind, and concentrated push loads. Various strengthening metal fittings have been proposed to improve lateral load resistance, particularly against seismic loads. This study introduces the use of post-compressed wedges as a novel reinforcement method for infill masonry walls to enhance lateral load resistance. The resistance of the infill masonry wall against lateral-concentrated push loads was assessed using an out-of-plane push-over test on specimens sized 2,300×2,410×190 mm³. The presence or absence of wedges and wedge spacing were set as variables. The push-over test results showed that both the unreinforced specimen and the specimen reinforced with 300 mm spaced wedges toppled, while the specimen reinforced with 100 mm spaced wedges remained upright. Peak loads were measured to be 0.74, 29.77, and 5.88 kN for unreinforced specimens and specimens reinforced with 100 mm and 300 mm spaced wedges, respectively. Notably, a tighter reinforcement spacing yielded a similar strength, as expected, which was attributed to the increased friction force between the masonry wall and steel frame. The W-series specimens exhibited a trend comparable to that of the displacement ductility ratio. Overall, the findings validate that post-compressed wedges improve the out-of-plane strength of infill masonry walls.

• Structural Engineering and Mechanics
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• v.56 no.6
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• pp.983-1001
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• 2015

This study focuses on the load carrying capacity and the force transfer mechanism of multi-hole perfobond shear connectors in steel-concrete composite structure. The behavior of multi-hole perfobond shear connector is more complicated than single-hole connector cases. 2 groups push-out tests were conducted. Based on the test results, behavior of the connection was analyzed and the failure mechanism was identified. Simplified iterative method and analytic solution were proposed based on force equilibrium for analyzing multi-hole perfobond shear connector performance. Finally, the sensitivity of design parameters of multi-hole perfobond shear connector was investigated. The results of this research showed that shear force distribution curve of multi-hole perfobond shear connector is near catenary. Shear forces distribution were determined by stiffness ratio of steel to concrete member, stiffness ratio of shear connector to steel member, and number of row. Efficiency coefficient was proposed to should be taking into account in different limit state.

• Journal of the Korean Society of Safety
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• v.23 no.3
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• pp.42-50
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• 2008

This study, push-off tests for the initially uncracked specimens were conducted to investigate shear transfer mechanism in reinforce concrete elements. Experimental programs for shear transfer were undertaken to investigate the effect of the concrete compressive strength, the presence of steel stirrups as shear reinforcement and the amount of steel stirrups. As the shear plane is loaded, several cracks form in a direction inclined to the shear plane, creating compression struts in the concrete. For this stage, shear is being transferred through a truss-like action produced by the combination of the compressive force in the concrete struts and the tensile force that the steel reinforcement crossing the shear plane develops. In the normal strength concrete specimens with steel stirrups, ultimate failure occurred when the compression struts crushed in concrete. In the high strength concrete specimens, on the other hand, ultimate failure occurred when the steel stirrups developed their yield strength.

• Korean Journal of Applied Biomechanics
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• v.27 no.2
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• pp.141-147
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• 2017

Objective: We obtained force-displacement curves for countermovement jumps of multiple heights and examined the effect of an arm swing on changes in vertical jumping strategy. Countermovement jumps with hands on hips (Condition 1) and with an arm swing (Condition 2) were evaluated to investigate the mechanical effect of the arm movement on standing vertical jumps. We hypothesized that the ground reaction force (GRF) and/or center of mass (CoM) motion resulting from the countermovement action would significantly change depending on the use of an arm swing. Method: Eight healthy young subjects jumped straight up to five different levels ranging from approximately 10% (~25 cm) to 35% (~55 cm) of their body heights. Each subject performed five sets of jumps to five randomly ordered vertical elevations in each condition. For comparison of the two jumping strategies, the characteristics of the boundary point on the force-displacement curve, corresponding to the vertical GRF and the CoM displacement at the end of the countermovement action, were investigated to understand the role of arm movement. Results: Based on the comparison between the two conditions (with and without an arm swing), the subjects were grouped into type A and type B depending on the change observed in the boundary point across the five different jump heights. For both types (type A and type B) of vertical jumps, the initial vertical force at the start of push-off significantly changed when the subjects employed arm movement. Conclusion: The findings may imply that the jumping strategy does change with the inclusion of an arm swing, predominantly to modulate the vertical force advantage (i.e., the difference between the vertical force at the start of push-off and the body weight).

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.3
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• pp.75-86
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• 2005

To investigate the fatigue characteristic of upper limbs, this study analyzed RMS(root mean square) and MPF(mean power frequency) value between initial and terminal stages of each experiment condition. And the effect of intermittent endurance time was evaluated using the Borg's CR10 value that was measured for the parts of upper limb. According to the results of ANOVA on RMS value, there were significant difference on the %MVC about push, pull, and down force exertion. Particularly the ANOVA of up force exertion was significant difference on shoulder flexion, elbow flexion and rest time as well as %MVC. The results of ANOVA for MPF value were significant difference on the %MVC in regard of the push and up force exertion. In case of up force exertion, MPF value tended to shift low frequency at all of the experiment conditions. According to the analysis of duty cycle, RMS value considerably increased over 50% duty cycle and as the %MVC increased, the duty cycle affected the increase of RMS value. MPF value for up and down force exertion decreased at 33%, 50% and 67% duty cycle for all of %MVC. Borg CR10 value of hand and forearm were below the 3-point to the 40% of endurance time at 30%MVC and to the 20% of endurance time at 50%MVC with the exception of up force exertion. But Borg CR10 values of upper arm and shoulder at up force exertion were more than 3-point to the 20% of endurance time at 30%MVC and in the start point of endurance time at 50%MVC.

• Journal of Korean Society of Steel Construction
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• v.17 no.6 s.79
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• pp.737-747
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• 2005

The connection of the slab with the steel beam and thus, the transmission of shear force at the interface of the steel-concrete composite beams is achieved with shear connectors, in general, with shear studs. The composite action through these shear studs has a significant influence on the load carrying behavior of the composite beams. The load carrying capacity of studs is determined through push-out tests. At present, the transferability of this load carrying capacity of studs to composite beams, especially in cases of partial interaction, is being questioned by experimental and theoretical investigations. In this study, a finite element model for the simulation of the behavior of the standard push-out specimen and the composite beams without the implementation of the load-slip curve of the stud connectors from the push-out test is developed. The load carrying behavior of the studs in the composite beams is estimated and compared with the results of the push-out test. The reason for the difference in the load carrying behavior of the studs in the push-out test specimen and in the composite beams is found.

• Computational Structural Engineering
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• v.10 no.4
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• pp.281-290
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• 1997

Current seismic design code is based on the assumption that the designed structures would be behaved inelastically during a severe earthquake ground motion. For this reason, seismic design forces calculated by seismic codes are much lower than the forces generated by design earthquakes which makes structures responding elastically. Present procedures for calculating seismic design forces are based on the use of elastic spectra reduced by a strength reduction factors known as "response modificaion factor". Because these factors were determined empirically, it is difficult to know how much inelastic behaviors of the structures exhibit. In this study, lateral strength required to maintain target ductility ratio was first calculated from nonlinear dynamic analysis of the single degree of freedom system. At the following step, base shear foeces specified in seismic design code compare with above results. If the base shear force required to maintain target ductility ratio was higher than the code specified one, the lack of required strength should be filled by overstrength and/or redundancy. Therefore, overstrength of moment resisting frame structure will be estimated from the results of push-over analysis.

• Steel and Composite Structures
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• v.51 no.1
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• pp.9-24
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• 2024

In order to study the shear mechanical behavior of prefabricated and assembled multi-key group stud connectors, this paper conducted push-out tests on 10 prefabricated and assembled multi-key group stud connectors, distributed in 5 groups, and detailed the failure modes of each specimen. Based on the finite element software, a total of 22 models of this type of stud connector are established, and validated the finite element models using the push-out tests. Furthermore, the effects of stud diameter, number of key groups, and spacing of key groups on the shear resistance of prefabricated and assembled multi-key group stud connectors are analyzed. Combined with the test and finite element, the force analysis is carried out for the stud and first-pouring and post-pouring concrete. The results show that the spacing and number of key groups have a significant impact on the shear capacity and shear stiffness of the specimen. For a single stud, the shear force is transferred to the surrounding concrete via the stud's root. When the stud is finally cut, the steel and the concrete plate are separated. Under vertical shear force, the top row of studs experiences the highest shear, while the middle row has the least. Based on statistical regression, a formula of assembled multi-key group stud connectors is proposed.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.5
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• pp.257-263
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• 2018

It is a small injection molding machine for table top considering the material heating mechanism and the design and structure stability by securing the mechanism that compresses the inside of the material heating tube by using the electric actuator and by providing space between the body and the material heating tube to reduce heat loss Develop body. An electric actuator suitable for applying pressure to the inside of a material heating tube is a mechanical system composed of a rigid structure. Since a large force is repeatedly applied to the electric actuator and the push rod, the interaction between the moving parts and the dynamic Maximum stress through analysis and prediction of fatigue life of critical parts The pushrod reflects the structural analysis results of the electric actuator and the push rod, and pushes the inside of the material heating tube by the push rod to inject the molten material from the nozzle into the mold. The pushrod operates by the operation of the electric actuator. The material heated by the coil heater is ejected through the nozzle by the pressure of the material heating tube, and the material heating tube and the nozzle are also lowered at the same time as the push rod is lowered, so that the material is closely adhered to the mold. We want to study the completion of the injection.