• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.5
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• pp.339-345
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• 2021

Finite element analysis of the silo type underground opening for low- and intermediate-level radioactive waste (LILW) disposal facilities in Korea is presented in this study. The silo wall is circular and the roof is made up of domes. The silo wall is 25 meters in diameter, 35 meters in height, and the dome is 30 meters in diameter and 17.4 meters in height, and it is located at -80 meters to -130 meters at sea level. Although six silos have been constructed in the first stage and are in operation, only one silo was considered in this study. The two-dimensional axial symmetric finite element model, as well as the three-dimensional finite element model were made using the computer program SMAP-3D. Generalized Hoek and Brown Model was used for the numerical analyses. The finite element analysis of the silo type underground opening was carried out under various lateral pressure coefficients (defined as ratio of average horizontal to vertical in-situ stress), and the numerical results of these analyses were examined.

• Land and Housing Review
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• v.12 no.3
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• pp.97-108
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• 2021

In bridge abutment structures, lateral squeeze due to lateral stress of embankment placement and thermal movement of the bridge structure leads to failure of approach slabs, girders, and bridge bearings. Recently, GRS (Geosynthetic-Reinforced Soil) integral bridge has been proposed as a new countermeasure. The GRS integral bridge is a combining structure of a GRS retaining wall and an integral abutment bridge. In this study, numerical analyses which considered construction sequences and earthquake loading conditions are performed to compare the behaviors of conventional PSC (Pre-Stressed Concrete) girder bridge, traditional GRS integral bridge structure and GRS integral bridge with bracket structures (newly developed LH-type GRS integral bridge). The analysis results show that the GRS integral bridge with bracket structures is most stable compared with the others in an aspect of stress concentration and deformation on foundation ground including differential settlements between abutment and backfill. Furthermore, the GRS integral bridge with/without bracket structures was found to show the best performance in terms of seismic stability.

• Tunnel and Underground Space
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• v.32 no.3
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• pp.219-230
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• 2022

The Geo-Reservoir Experimental Analogue Technology (GREAT) cell was designed to recreate the thermal-hydro-mechanical conditions of deep subsurface in the laboratory. This apparatus can generate a polyaxial stress field using lateral loading elements, which rotate around the longitudinal axis of a sample and is capable of performing a fluid flow test for samples containing fractures. In the present study, numerical simulations were carried out for triaxial compression tests using the GREAT cell and the mechanical behavior of samples under different conditions of lateral loading was investigated. We simulated an actual case, in which triaxial compression tests were conducted for a polymer sample without fractures, and compared the results between the numerical analysis and experiment. The surface strain (circumferential strain) of the sample was analyzed for equal and non-equal horizontal confining pressures. The results of the comparison showed a good consistency. Additionally, for synthetic cases with a fracture, we investigated the effect of the friction and type of fracture surface on the deformation behavior.

• Geomechanics and Engineering
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• v.30 no.2
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• pp.169-185
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• 2022

The urbanization and increasing rate of population demands effective means of transportation system (basement and tunnels) as well as high-rise building (resting on piled foundation) for accommodation. Therefore, it unavoidable to construct basements (i.e., excavation) nearby piled foundation. Since the basement excavation inevitably induces soil movement and stress changes in the ground, it may cause differential settlements to nearby piled raft foundation. To understand settlement and load transfer mechanism in the piled raft due to excavation-induced stress release, numerical parametric studies are carried out in this study. The effects of excavation depths (i.e., formation level) relative to piled raft were investigated by simulating the excavation near the pile shaft (i.e., H_e/L_p=0.67), next to (H_e/L_p=1.00) and below the pile toe (H_e/L_p=1.33). In addition, effects of sand density and raft fixity condition were investigated. The computed results have revealed that the induced settlement, tilting, pile lateral movement and load transfer mechanism in the piled raft depends upon the embedded depth of the diaphragm wall. Additional settlement of the piled raft due to excavation can be account for apparent loss of load carrying capacity of the piled raft (ALPC). The highest apparent loss of piled raft capacity ALPC (on the account of induced piled raft settlement) of 50% was calculated in in case of H_e/L_p = 1.33. Furthermore, the induced settlement decreased with increasing the relative density from 30% to 90%. On the contrary, the tilting of the raft increases in denser ground. The larger bending moment and lateral force was induced at the piled heads in fixed and pinned raft condition.

• Journal of Korean Foot and Ankle Society
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• v.26 no.1
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• pp.16-21
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• 2022

When an ankle lateral malleolar fracture is accompanied by a deltoid ligament rupture without a medial malleolar fracture, such an injury is called a bimalleolar equivalent fracture. This means that even if there is no bony injury on the medial side, there may be functional instability of the ankle joint due to damage to the deltoid ligament. Manual or gravity external rotational stress radiography is used to differentiate an ankle bimalleolar equivalent fracture from an isolated lateral malleolar fracture. If the medial joint gap is widened on the stress radiography, the deltoid ligament injury can be diagnosed, and surgical treatment for fibula fractures is recommended. After open reduction of the fibula fracture (with syndesmotic fixation if needed), a decision on the repair of the deltoid ligament is taken depending on the surgeons' preference and intraoperative findings. The deltoid ligament repair is performed by inserting a suture anchor (or anchors) in the medial malleolus and fixing the deep and superficial deltoid ligaments to the medial malleolus. The only randomized study to evaluate the utility of deltoid ligament sutures in ankle fractures did not support the deltoid ligament suture, but the study itself had many limitations. An appropriately powered, randomized, controlled trial of the deltoid ligament repair with both patient-reported outcome and radiographic outcome evaluation is needed in the future.

• The korean journal of orthodontics
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• v.29 no.4 s.75
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• pp.411-424
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• 1999

The purpose of this study was to find the difference of stress distribution of initial compressive and tensile stress when anterior section of upper utility arch was activated crown lingual torque of $5^{\circ},\;10^{\circ},\;15^{\circ}$ through three-dimensional finite element analysis. For this study the finite element model of upper central and lateral incisors, 1st. and 2nd. premolars and 1st. molars and each periodontal membrane and upper utility arch were made. From the solutions of ANSYS the followings were obtained. 1. $5^{\circ},\;10^{\circ},\;15^{\circ}$ crown lingual torque produce the almost similar distribution and measurement of initial compressive and tensile stress. 2. Acivated upper utility arch torqued central inciors lingually and lateral incisors labially.

• Journal of the Korean GEO-environmental Society
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• v.12 no.1
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• pp.41-50
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• 2011

Three-dimensional(3D) numerical analyses have been conducted to study the behaviour of a single pile to adjacent tunnelling conducted in the lateral direction of the pile. In the numerical analyses, the interaction between the tunnel, the pile and the soil next to the pile has been analysed. The study includes the pile settlement, the relative shear displacement between the pile and the soil, the shear stresses at the soil next to the pile and the axial force on the pile. In particular, the shear stress transfer mechanism along the pile related to the tunnel advancement has been rigorously analysed. Due to changes in the relative shear displacement between the pile and the soil next to the pile during the tunnel advancement, the shear stress and the axial force distributions along the pile have been changed. Downward shear stress developed above the tunnel springline (Z/L=0.0-0.7~0.8), while upward shear stress is mobilised below the tunnel springline (Z/L=0.7~0.8-1.0) resulting in compressive force on the pile, where Z is the pile location and L is the pile length. Maximum compressive force of about $0.475P_a$ was developed on the pile after completion of tunnel advancement, where $P_a$ is the allowable pile capacity. Some insights into the pile behaviour to tunnelling obtained from the numerical analyses will be reported and discussed.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.2
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• pp.327-353
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• 1994

This study was performed to evaluate the effects of number and alignment of implant fixture and various bar designs on the retention of denture and the stress distribution. Six kinds of photoelastic mandibular models and nine kinds of overdenture specimens were designed. A unilateral vertical load was gradually applied on the right first molar to calculate the maximal dislodgement load of each specimen. A unilateral vertical load of 17 Kgf was applied on the right first molar and a vertical load of 10 Kgf was applied on the interincisal edge region. The stress pattern which developed in each photoelastic model was analyzed by the reflection polariscope. The results obtained were as follows: 1. The maximal dislodgement load reversely increased with the distance from the loading point to the implant fixture, while it linearly increased with that from the most posterior implant fixture to the mesial clip. The maximal dislodgement load also increased with the use of a cantilever bar. 2. Under the posterior vertical load, the stress to the supporting tissue of the denture base increased with the distance from the loading point to the implant future. The stress concentration on the apical area of the implant future reversely increased with the distance from the loading point to the implant future. 3. In the overdentures supported by two implant fixtures under the posterior vertical load. the specimen implanted on lateral incisor areas with a cantilever bar exhibited more favorable stress distribution than that without a cantilever bar. The specimen implanted on the canine areas without a cantilever bar, however, exhibited more favorable stress distribution. 4. In the overdentures supported by three implant fixtures. the specimen implanted ell the midline and canine areas exhibited more favorable stress distribution than that implanted oil the midline and the first premolar areas. 5. In the overdentures supported by four implant fixtures. the specimen implanted with two adjacent implant fixtures exhibited more favorable stress distribution than that implanted at equal distance under the posterior vertical load. 6. Under the anterior vertical load, the overdentures supported by three implant fixtures exhibited stress concentration on the supporting structure of the middle implant future. In overdentures supported by two or four implant futures, no significant difference was noted in stress distribution between the types of bars. These results indicate that the greater the number of implant fixtures, the better the stress distribution is. A favorable stress distribution may be obtained in the overdentures supported by two or three implant fixtures, if the location and the design of the bar are appropriate.

• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.4
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• pp.277-288
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• 2002

Seven finite element models were constructed in mandible having single screw-type implant fixture connected to the premolar superstructure, in order to evaluate how the length, diameter and platform shape of a screw-type fixture influence the stress in the supporting tissue around fixtures. Each finite element model was varied in terms of length, diameter, and platform shape of the fixture. In each model, 250N of vertical load was placed on the central pit of an occlusal plane and 250N of oblique load placed on the buccal cusp. The stress distribution in the supporting tissue and the other components was analysed using 2-dimensional finite element analysis and the maximum von Mises stress in each reference area was compared. Under lateral loading, the stress was larger at the abutment/fixture interface, and in the crestal bone, compared to the stress pattern under vertical loading. The amount of stress at the superstructure was similar regardless of the length, diameter and platform shape of a fixture. Around the longer fixture, the stress was decreased at the bone crest and subjacent cancellous bone and increased in the cancellous bone area apical to the fixture. Around the wider fixture, the stress was decreased at the abutment/fixture interface, and the bone crest and increased in the cancellous bone area apical to the fixture. Around the fixture having wider platform, less stress was produced at the abutment/fixture interface and the upper part of the cortical bone, compared to the fixture having standard platform. In conclusion, the stress distribution of the supporting tissue was affected by length, diameter, and platform shape of a fixture, and the fixture which was larger in diameter and length could reduce the stress in the supporting tissues at the bone-fixture interface and bone crest area.

• Journal of Biomedical Engineering Research
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• v.21 no.3 s.61
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• pp.261-271
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• 2000

The present study investigated flow dynamics of a two-dimensional abdominal aortic bifurcation model under sinusoidal flow conditions considering wall motion. impedance phase angle(time delay between pressure and flow waveforms), and non-Newtonian fluid using computational fluid dynamics. The wall shear stress showed large variations in the bifurcated region and the wall motion reduced amplitude of wall shear stress significantly. As the impedance phase angle was changed to more negative values, the mean wall shear stress (time-averaged) decreased while the amplitude (oscillatory) of wall shear stress increased. At the curvature site on the outer wall where the mean wall shear stress approached zero. influence of the phase angle was relatively large. The mean wall shear stress decreased by $50\%$ in the $-90^{\circ}$ phase angle (flow wave advanced pressure wave by a quarter period) compared to the $0^{\circ}$ phase angle while the amplitude of wall shear stress increased by $15\%$. Therefore, hypertensive patients who tend to have large negative phase angles become more vulnerable to atherosclerosis according to the low and oscillatory shear stress theory because of the reduced mean and the increased oscillatory wall shear stresses. Non-Newtonian characteristics of fluid substantially increased the mean wall shear stress resulting in a less vulnerable state to atherosclerosis.