• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.5
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• pp.887-897
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• 2018

3D time history analysis was performed on vertical shaft-tunnel connection to provide insight into the dynamic stress-strain behavior of the connection considering the effects of soil layers, periodic characteristics and wave direction of earthquakes. MIDAS GTS NX based on FEM (Finite Element Method) was used for this study. From this study, it is revealed that the maximum displacement occurred at the upper part of the connection when the long period seismic waves propagate through the tunnel direction in soft ground. Also, stress concentration occurs due to different behaviors of vertical shaft and tunnel, and the stress concentration could be influence for safety on the connection. The results of this study could be useful for the seismic performance design of vertical shaft-tunnel connection.

• International Journal of Highway Engineering
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• v.20 no.4
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• pp.15-20
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• 2018

PURPOSES : The purpose of this study is to analyze the magnitude of shoving of asphalt pavement by junction type between airport concrete and asphalt pavements, and to suggest a junction type to reduce shoving. METHODS : The actual pavement junction of a domestic airport, which is called airport "A" was modified by placing the bottom of the buried slab on the top surface of the subbase. A finite element model was developed that simulated three junction types: a standard section of junction proposed by the FAA (Federal Aviation Administration), an actual section of junction from airport "A" and a modified section of junction from airport "A". The vertical displacement of the asphalt surface caused by the horizontal displacement of the concrete pavement was investigated in the three types of junction. RESULTS : A vertical displacement of approximately 13 mm occurred for the FAA standard section under horizontal pushing of 100 mm, and a vertical displacement of approximately 55 mm occurred for the actual section of airport "A" under the same level of pushing. On the other hand, for the modified section from airport "A" a vertical displacement of approximately 17 mm occurred under the same level of pushing, which is slightly larger than the vertical displacement of the FAA standard section. CONCLUSIONS : It was confirmed that shoving of the asphalt pavement at the junction could be reduced by placing the bottom of the buried slab on the top surface of the subbase. It was also determined that the junction type suggested in this study was more advantageous than the FAA standard section because it resists faulting by the buried slab that is connected to the concrete pavement. Faulting of the junctions caused by aircraft loading will be compared by performing finite element analysis in the following study.

• Structural Engineering and Mechanics
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• v.44 no.2
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• pp.257-266
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• 2012

Walls are the most important vertical load-carrying elements of masonry structures. Their bond designs are different from one country to another. This paper presents the shear effects of some structural bond designs commonly used for masonry walls. Six different bond designs are considered and modeled using finite element procedures under lateral loading to examine the shear behavior of masonry walls. To obtain accurate results, finite element models are assumed in the inelastic region. Crack development patterns for each wall are illustrated on deformed meshes, and the numerical results are compared.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.10a
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• pp.267-274
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• 1996

Differential shortening of vertical members in high-rise buildings affect other structural members that have to be considered such as horizontal members and exterior cladding. of many elements which affect the total amount of shortening, different loading history mainly comes from the different construction time. Shortening of 66 story concrete columns were investigated and compared according to the different construction time, little difference was found between the total shortening of interior and that of exterior column.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.03a
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• pp.258-262
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• 1998

A structural design based of finite element analysis has been performed to investigate the reliable automatic transport system. For the procedure, different cross-sectional geometric factors were calculated and compared in detail. The von-Mises stresses were chosen to maintain a solid loading braring capacity for the safe design. Parametric studies showed that it is more inportant for the plate bending problem than the vertical loads of hanging bar to assess the safe and economic structural design.

• Korean Management Science Review
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• v.26 no.1
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• pp.93-112
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• 2009

In this paper, a model is presented to estimate a cycle time for completing an operation in a new type of AS/RS which can handle very heavy loads by separating the mechnisms for vertical and horizontal movements. Considering loading/unloading time between devices, we generalize the previous work, Hu et al. [9], which neglected the transfer time. Through the numerical experiments for various situations, we find that the difference of the cycle times between two models is fairly large and conclude that the transfer time between devices cannot be neglected at all.

• Architectural research
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• v.3 no.1
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• pp.45-52
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• 2001

In this paper, a pressurized single vertical arch and a pressurized leaning arch composed of flexible fabric material are considered. These arches have also been considered as a possible support structure for the tent-like structures. Two different boundary conditions are considered in leaning arches with fixed bases and pinned bases. The behaviors of the leaning arches are investigated for two tilt angles as 15, 30. For each angle, two loading conditions are considered as uniformly distributed load and wind loads. The F.E.M. is used through the all analysis procedures. For the results, load-deflection relationships, buckling modes, differences between two boundary conditions and deformed configurations are discussed.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.2
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• pp.226-237
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• 2004

Purpose: Four finite element models were constructed in the mandible having a single implant fixture connected to the first premolar-shaped superstructure, in order to evaluate how the shape of the fixture and the implant-abutment connection would influence the stress level of the supporting tissues fixtures, and prosthethic components. Material and methods : The superstructures were constructed using UCLA type abutment, ADA type III gold alloy was used to fabricate a crown and then connected to the fixture with an abutment screw. The models BRA, END , FRI, ITI were constructed from the mandible implanted with Branemark, Endopore, Frialit-2, I.T.I. systems respectively. In each model, 150 N of vertical load was placed on the central pit of an occlusal plane and 150 N of $40^{\circ}$ oblique load was placed on the buccal cusp. The displacement and stress distribution in the supporting tissues and the other components were analysed using a 2-dimensional finite element analysis . The maximum stress in each reference area was compared. Results : 1. Under $40^{\circ}$ oblique loading, the maximum stress was larger in the implant, superstructure and supporting tissue, compared to the stress pattern under vertical loading. 2. In the implant, prosthesis and supporting tissue, the maximum stress was smaller with the internal connection type (FRI) and the morse taper type (ITI) when compared to that of the external connection type (BRA & END). 3. In the superstructure and implant/abutment interface, the maximum stress was smaller with the internal connection type (FRI) and the morse taper type (ITI) when compared to that of the external connection type (BRA & END). 4. In the implant fixture, the maximum stress was smaller with the internal connection type (FRI) and the morse taper type (ITI) when compared to that of the external connection type (BRA & END). 5 The stress was more evenly distributed in the bone/implant interface through the FRI of trapezoidal step design. Especially Under $40^{\circ}$ oblique loading, The maximum stress was smallest in the bone/implant interface. 6. In the implant and superstructure and supporting tissue, the maximum stress occured at the crown loading point through the ITI. Conclusion: The stress distribution of the supporting tissue was affected by shape of a fixture and implant-abutment connection. The magnitude of maximum stress was reduced with the internal connection type (FRI) and the morse taper type (ITI) in the implant, prosthesis and supporting tissue. Trapezoidal step design of FRI showed evenly distributed the stress at the bone/implant interface.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.2
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• pp.111-118
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• 2013

Purpose of present study is to investigate the effects of thread pitch in coronal portion in scalloped implant with 2 different connections on loading stress using 3 dimensional finite element analysis. Scalloped implant with 4 different thread pitches (0.4mm, 0.5mm, 0.6, and 0.7mm) in the coronal part was modeled with 2 different implant-abutment connections. Platform matching connection had the same implant and abutment diameter so that they were in flush contact at the periphery while platform mismatching connection had smaller abutment diameter than implant so that their connection was made away from periphery of implant-bone interface. Occlusal loading of 100N force was applied vertically and 30 degree obliquely to all 8 models and the maximum von Mises bone stress was identified. Loading stress as highly concentrated in cortical bone. Platform mismatching scalloped implant with small thread pitch (0.4mm) model had consistently lowest maximum von Mises bone stress in vertical and oblique loads. Platform matching model had lowest maximum von Mises bone stress with 0.6mm thread pitch in vertical load and with 0.4mm thread pitch in oblique load. Platform mismatching connection had important roles in reducing maximum von Mises bone stress. Scalloped implant with smaller coronal thread pitch showed trend of reducing maximum von Mises bone stress under load.

• Korean Journal of Applied Biomechanics
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• v.28 no.2
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• pp.101-108
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• 2018

Objective: The aim of this study was to investigate gender differences in ground reaction force (GRF) components among different speeds of running. Method: Twenty men ($age=22.4{\pm}1.6years$, $mass=73.4{\pm}8.4kg$, $height=176.2{\pm}5.6cm$) and twenty women ($age=20.7{\pm}1.2years$, $mass=55.0{\pm}8.2kg$, $height=163.9{\pm}5.3cm$) participated in this study. All participants were asked to run on an instrumented dual belt treadmill (Bertec, USA) at 8, 12, and 16 km/h for 3 min, after warming up. GRF data were collected from 30 strides while they were running. Hypotheses were tested using one-way ANOVA, and level of significance was set at p-value <.05. Results: The time to passive peaks was significantly earlier in women than in men at three different running speeds (p<.05). Further, the impact loading rates were significantly greater in women than in men at three different running speeds (p<.05). Moreover, the propulsive peak at 8 km/h, which is the slowest running speed, was significantly greater in women than in men (p<.05), and the vertical impulse at 16 km/h, which is the fastest running speed, was significantly greater in men than in women (p<.05). The absolute anteroposterior impulse at 8 km/h was significantly greater in women than in men (p<.05). In addition, as the running speed increased, impact peak, active peak, impact loading rate, breaking peak, propulsive peak, and anteroposterior impulse were significantly increased, but vertical impulse was significantly decreased (p<.05). Conclusion: The impact loading rate is greater in women than in men regardless of different running speeds. Therefore, female runners might be exposed to the risk of potential injuries related to the bone and ligament. Moreover, increased running speeds could lead to higher possibility of running injuries.