• Journal of Biosystems Engineering
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• v.30 no.6 s.113
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• pp.366-372
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• 2005

The objective of this study was to evaluate the bump crossing and loading stability of a proto-type mini-forwarder under development. The evaluation was performed by computer simulation using a multi-body dynamic analysis program, Recur- Dyn 5.21. The proto-type was modeled and its properties such as mass, mass center, and mass moment of inertia were determined using 3D CAD modeler, Solid Edge 8.0. The $\%$ errors of masses, mass center, mass moment of inertia, and vertical motion of the model were within less than $10\%$ and the model's behavior agreed relatively well with those of the proto-type when traversing over a rectangular bump. Using the validated model, bump crossing of the proto-type was simulated and the loading limit was determined. It was found that effects of the shapes of bump on the bump crossing performance was insignificant within the practical heights of bumps. Stability of bump crossing increased with loading. However, loading of longer logs than 2.7 m made the crossing unstable because the ends of logs contacted ground when traversing over the bump. The maximum loading capacity of the proto-type was estimated to be 7.8 kN of 2.7 m long logs.

• The korean journal of orthodontics
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• v.41 no.5
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• pp.337-345
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• 2011

Objective: The purpose of this study was to evaluate the effect of force and moment produced by Nickel-titanium wires of different sizes at activation and deactivation according to differing vertical bracket displacement. Methods: Superelastic NiTi wires of 3 different sizes (0.014", 0.016", and 0.016" ${\times}$ 0.022") were tied with elastomeric or 0.009-inch stainless steel ligations in a twin-bracket, 0.018-inch slot. A testing machine recorded the effects of simulated activation of 5 distances from 1 to 5 mm and deactivation of 5 distances from 4 to 0 mm, in increments of 1 mm. Results: Frictional force increased the wire stiffness during loading. Ligation of 0.014-inch NiTi wire with O-ring resulted in a significant increase in the stiffness. On application of orthodontic force for 5 mm of vertical displacement of teeth, the effective displacement in the case of the 0.014", 0.016", and 0.016" ${\times}$ 0.022" NiTi wires was 2 mm, 3 mm, and 4 mm, respectively. Conclusions: Our results showed that movement of teeth with large vertical displacement was ineffective because of excessive friction. This finding might contribute to the understanding of the force system required for effective teeth movement and thereby facilitate the application of the appropriate light wire for leveling and alignment.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.3
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• pp.103-110
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• 2022

The purpose of this study is to experimentally evaluate the stiffness and strength reduction according to the reinforcing bar details of the vertically divided reinforced concrete shear walls. To confirm the effect of reducing strength and stiffness according to vertical division, four real-scale specimens were fabricated and repeated lateral loading tests were performed. As a result of the experiment, it was confirmed that the strength and stiffness were decreased according to the vertical division. In particular, as the stiffness reduction rate is greater than the strength reduction rate, it is expected that safety against extreme strength can be secured when the load is redistributed according to vertical division. As a result of checking the crack pattern, a diagonal crack occurred in the wall subjected to compression control among the divided walls. It was confirmed that two neutral axes occurred after division, and the reversed strain distribution appeared in the upper part, showing the double curvature pattern. In future studies, it is necessary to evaluate the stiffness reduction rate considering the effective height of the wall, to evaluate additional variables such as wall aspect ratio, and to conduct analytical studies on various walls using finite element analysis.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.22-29
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• 2023

In the evaluation of seismic performance for structural materials and components, the loading rate and axial force can have a significant impact. Due to time-delay effects between input and output displacements, It is difficult to apply high-rate displacement in cyclic tests and hybrid simulations. Additionally, the difficulty of maintaining a consistent vertical load in the presence of lateral displacement has limited fast and real-time tests performed while maintaining a constant vertical load. In this study, slow, fast cyclic tests and real-time hybrid simulations were conducted to investigate the rate dependency and the influence of vertical loads of Isolation Bearing. In the experiment, the FLB System including an Adaptive Time Series (ATS) compensation and a state estimator was constructed for real-time control of displacement and vertical load. It was found that the vertical load from the superstructure and loading rate can have a significant impact on the strength of the seismic isolation bearing and its behavior during an earthquake. When conducting experiments for seismic performance evaluation, they must be implemented to be similar to reality. This study demonstrates the excellent performance of the system built and used for seismic performance evaluation and enables accurate and efficient seismic performance evaluation.

• Journal of Welding and Joining
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• v.21 no.4
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• pp.87-91
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• 2003

Effects of the circular and non-circular pad shapes on self-alignment in BGA soldering are predicted using Surface Evolver, and the calculated results are compared with experimental data. While the pad shape has minor effects on self-alignment in the vertical direction, self-alignment in the lateral direction depends on the pad direction and length ratio of the non-circular pad. Larger restoring force is obtained in the minor-axis direction than the major-axis direction, which suggests a possibility of reducing misalignment in the specific direction. The restoring force of the circular pad is between those of the non-circular pad in the major and minor-axis directions. The calculated results of Surface Evolver show reasonably good agreements with experimental data using the shear loading system.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.197-202
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• 2001

It is necessary to Investigate long-term behavior of vertical members such as column and shear wall because the long-term behavior induces the serviceability problem of reinforce-concrete structures. However, the long-term behavior on shear wall has not been fully studied. Experimental works are performed to understand the time dependent behavior of shear wall, especially the effect of loading area in this research. Three different types of cross sections are adopted, i.e., 10$\times$10 cm, 10$\times$30 cm, and 10$\times$50 cm with the same loading area of 10$\times$10 cm. The creep strains were different from point to point in the section of the shear wall specimen because of the nonlinear stress distribution. The effect of the nonlinear stress distribution was larger in the specimen with the larger width.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.125-128
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• 2002

The uplift capacity and displacement of an earth anchor for improving the wind resistance of the 1-2W type plastic film pipe on greenhouse was tested using the steel circular vertical earth anchor with various diameters and embedded depths (L) in dry sand. The diameter (B) of the model anchor is 90mm, 120mm, 150mm, respectively. The model tests were performed embedded depth ratios (L/B) ranging from $1{\sim}3$ in loose density. In the case of diameter 90mm, as the uplift loading increased, the uplift capacity also increased until the loading was reached to ultimate uplift capacity. After that, the uplift capacity was continually increased or decreased until the experiment was finished. In general, the ultimate uplift capacity was different depending upon the anchor diameter and embedded depth ratios.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.182-187
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• 2003

The analysis of mud pumping which causes track irregularities during softening of present roadbed is needed in order to prepare countermeasure that is efficient and reasonable against the softening of railway roadbed. In this study, model tests were performed in order to evaluate property of the railway softening under the train loading, considering the wheel load and the impact coefficient due to the train passing velocity. The existence of the mud pumping, settlements of roadbed and vertical earth pressure were measured under the train loading.

• Journal of Industrial Technology
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• v.22 no.B
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• pp.211-218
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• 2002

The paper is to show the behavior of composit ground which is installed with sheet pile in soft soil improved by sand compaction pile. The results of load-settlement relationship, earth pressure, stress concentration characteristics, and final water content were obtained by centrifuge model test. Two cases of tests, installation of sheet pile on the corner and both side of the loading plate for the improved SCP ground which was designed twice of the footing width, were performed for the tests under the vertical and horizontal loading and both side of corner. Finite element program(CRISP) for sand compaction pile using elasto-plastic model and numerical analysis for soft soil using modified cam-clay constitutive equation were compared and analized with the results of model tests. The result of analysis show the increased bearing capacity of soil after, SCP and sheet pile was installed.

• Coupled systems mechanics
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• v.2 no.1
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• pp.111-126
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• 2013

The structural design requirements of an offshore platform subjected to wave induced forces and moments in the jacket can play a major role in the design of the offshore structures. For an economic and reliable design; good estimation of wave loadings are essential. A nonlinear response analysis of a fixed offshore platform under structural and wave loading is presented, the structure is discretized using the finite element method, wave plus current kinematics (velocity and acceleration fields) are generated using 5th order Stokes wave theory, the wave force acting on the member is calculated using Morison's equation. Hydrodynamic loading on horizontal and vertical tubular members and the dynamic response of fixed offshore structure together with the distribution of displacement, axial force and bending moment along the leg are investigated for regular and extreme conditions, where the structure should keep production capability in conditions of the 1-yr return period wave and must be able to survive the 100-yr return period storm conditions. The result of the study shows that the nonlinear response investigation is quite crucial for safe design and operation of offshore platform.