• The Journal of Korean Academy of Prosthodontics
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• v.36 no.2
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• pp.293-301
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• 1998

The purpose of this study was to investigate the effects of load on root that was applied to edentulous area in three simulated situation, in each case the guiding planes of abutment were right vertical, 95 degrees, or 100 degrees to residual ridge. The 2-dimensional finite element method was used and the finite element model was prepared as fellows. Right mandibular 1st and 2nd molar was lost and the 2nd premolar with distal rest was used as primary abutment which had three different degrees of guiding plane. Then 150N of compressive force was applied to central fossae of the 1st and 2nd molars and von Mises stress and displacement was measured. The results were as follows; 1. Irrespective of slopes of guiding planes, the stress was concentrated on mesial side of root apex and distal side of coronal portion of root, in particular on junction with distal alveolar bone. As slopes of guiding planes were increased. stress on root and compact bone surrounding abutment was increased but no considerable effect was seen on compact bone of residual ridge. 2. Distal side of coronal portion of root limited by periodontal ligament was displaced distally and mesial side of apical portion was mesially. With slope of guiding plane increasing, the pattern of displacement was similar with one another but the quantity was increased. 3. Both abutment & alveolar bone were displaced downward and root of abutment, especially distal side of coronal portion, was displaced severely. As the guiding plane was tiffed more mesially over $90^{\circ}$, the degree of displacement was also increased.

• Imaging Science in Dentistry
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• v.49 no.2
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• pp.79-86
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• 2019

Purpose: This study reviewed the common conditions associated with displacement of inferior alveolar nerve canal. Materials and Methods: General search engines and specialized databases including Google Scholar, Pub Med, Pub Med Central, Science Direct, and Scopus were used to find relevant studies by using keywords such as "mandibular canal", "alveolar canal", "inferior alveolar nerve canal", "inferior dental canal", "inferior mandibular canal" and "displacement". Results: About 120 articles were found, of which approximately 70 were broadly relevant to the topic. We ultimately included 37 articles that were closely related to the topic of interest. When the data were compiled, the following 8 lesions were found to have a relationship with displacement of mandibular canal: radicular/residual cysts, dentigerous cyst, odontogenic keratocyst, aneurysmal bone cyst, ameloblastoma, central giant cell granuloma, fibrous dysplasis, and cementossifying fibroma. Conclusion: When clinicians encounter a lesion associated with displaced mandibular canal, they should first consider these entities in the differential diagnosis. This review would help dentists make more accurate diagnoses and develop better treatment plans according to patients' radiographs.

• Structural Engineering and Mechanics
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• v.81 no.2
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• pp.147-161
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• 2022

The Brace-Type Shear Fuse (BSF) device is a newly proposed steel damper with excellent cumulative ductility and stable energy dissipation. In consideration of the current situation where there are not many alternatives for transversal seismic devices used in long-span three-tower self-anchored bridges (TSSBs), this paper implements improved BSFs into the world's longest TSSB, named Jinan Fenghuang Yellow River Bridge. The new details of the BSF are developed for the TSSB, and the force-displacement hysteretic curves of the BSFs are obtained using finite element (FE) simulations. A three-dimensional refined finite element model for the research TSSB was established in SAP2000, and the effects of BSFs on dynamic characteristics and seismic response of the TSSB under different site conditions were investigated by the numerical simulation method. The results show that remarkable controlling effects of BSFs on seismic response of TSSBs under different site conditions were obtained. Compared with the case without BSFs, the TSSB installed with BSFs has mitigation ratios of the tower top displacement, lateral girder displacement, tower bending moment and tower shear force exceeding 95%, 78%, 330% and 346%, respectively. Meanwhile, BSFs have a sufficient restoring force mechanism with a minor post-earthquake residual displacement. The proposed BSFs exhibit good application prospects in long-span TSSBs.

• Korean Journal of Remote Sensing
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• v.40 no.2
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• pp.141-150
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• 2024

Ground subsidence in urban areas is mainly caused by anthropogenic factors such as excessive groundwater extraction and underground infrastructure development in the subsurface composed of soft materials. Global Navigation Satellite System data with high temporal resolution have been widely used to measure surface displacements accurately. However, these point-based terrestrial measurements with the low spatial resolution are somewhat limited in observing two-dimensional continuous surface displacements over large areas. The synthetic aperture radar interferometry (InSAR) technique can construct relatively high spatial resolution surface displacement information with accuracy ranging from millimeters to centimeters. Although constellation operations of SAR satellites have improved the revisit cycle, the temporal resolution of space-based observations is still low compared to in-situ observations. In this study, we evaluate the extraction of a time-series of surface displacement in Incheon Metropolitan City, South Korea, using the small baseline subset technique implemented using the commercial software, Gamma. For this purpose, 24 COSMO-SkyMed X-band SAR observations were collected from July 12, 2011, to August 27, 2012. The time-series surface displacement results were improved by reducing random phase noise, correcting residual phase due to satellite orbit errors, and mitigating nonlinear atmospheric phase artifacts. The perpendicular baseline of the collected COSMO-SkyMed SAR images was set to approximately 2-300 m. The surface displacement related to the ground subsidence was detected approximately 1 cm annually around a few Incheon Subway Line 2 route stations. The sufficient coherence indicates that the satellite orbit has been precisely managed for the interferometric processing.

• Earthquakes and Structures
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• v.27 no.1
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• pp.57-67
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• 2024

To assess the seismic performance of Plate-Shell Integrated Concrete Liquid-Storage Structure (PSICLSS), a scaled test model was constructed. This model incorporated a hybrid isolation system, which combined shape memory alloy (SMA), lead-cored rubber isolation bearing (LRB) and sliding isolation bearing (SB). By conducting shaking table test, the dynamic responses of both non-isolated and hybrid-isolated PSICLSS were analyzed. The results show that the hybrid isolation system can effectively reduce the acceleration and displacement responses of the structure. However, it also results in an increase in local hydrodynamic pressure and liquid sloshing height. Under extreme earthquake action, the displacement of isolation layer is small. When vertical ground motion is taken into account, the shock absorption rate of horizontal acceleration decreases. The peak hydrodynamic pressure increases significantly, and the peak hydrodynamic pressure position also changes. The maximum displacement of isolation layer increases, the residual displacement decreases.

• Clinics in Shoulder and Elbow
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• v.24 no.1
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• pp.9-14
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• 2021

Background: Recent studies about completely displaced midshaft clavicle fractures have reported that their nonunion/malunion rates were significantly higher in conservatively treated patients compared to surgically treated patients. The purpose of this study was to evaluate the factors associated with treatment decisions for midshaft clavicle fractures and also the factors that affect patient satisfaction with their treatment choice. Methods: We retrospectively reviewed the records of 75 patients who had been diagnosed with a midshaft clavicle fracture and were treated conservatively at a single institution between March 1, 2013, and December 31, 2014. Their medical records were reviewed to investigate the severity of the initial vertical displacement. A telephone survey was carried out to identify the presence of any patient-perceived deformity and determine if the patient eventually underwent surgery and whether the patient would prefer surgery if the injury recurred. Results: Significantly more patients with vertical displacement ≥100% (9/28) eventually underwent surgery compared to patients with vertical displacement <100% (3/32, p=0.028). Patients with vertical displacement ≥100% (13/28) were significantly more likely to prefer surgery compared to patients with vertical displacement <100% (7/32, p=0.044). Among the conservatively treated patients, nine of 32 participants with a patient-perceived deformity and one of 16 without a patient-perceived deformity responded that they would prefer to receive surgery in same situation in the future (p=0.079). Conclusions: Patients with a midshaft clavicle fracture with vertical displacement of ≥100% may eventually require surgical treatment. When conservative treatment is carried out, the long-term patient results may be unsatisfactory due to perceived residual deformities.

• Geomechanics and Engineering
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• v.14 no.4
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• pp.387-398
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• 2018

The present study evaluates the interface shear strength between sand and different construction materials, namely steel and concrete, using direct shear test apparatus. The influence of surface roughness, mean size of sand particles, relative density of sand and size of the direct shear box on the interface shear behavior of sand with steel and concrete has been investigated. Test results show that the surface roughness of the construction materials significantly influences the interface shear strength. The peak and residual interface friction angles increase rapidly up to a particular value of surface roughness (critical surface roughness), beyond which the effect becomes negligible. At critical surface roughness, the peak and residual friction angles of the interfaces are 85-92% of the peak and residual internal friction angles of the sand. The particle size of sand (for morphologically identical sands) significantly influences the value of critical surface roughness. For the different roughness considered in the present study, both the peak and residual interaction coefficients lie in the range of 0.3-1. Moreover, the peak and residual interaction coefficients for all the interfaces considered are nearly identical, irrespective of the size of the direct shear box. The constitutive modeling of different interfaces followed the experimental investigation and it successfully predicted the pre-peak, peak and post peak interface shear response with reasonable accuracy. Moreover, the predicted stress-displacement relationship of different interfaces is in good agreement with the experimental results. The findings of the present study may also be applicable to other non-yielding interfaces having a similar range of roughness and sand properties.

• Earthquakes and Structures
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• v.19 no.2
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• pp.129-144
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• 2020

In this study, the idea of damping force linearly proportional to horizontal isolation displacement is implemented into sloped rolling-type bearings in order to meet different seismic performance goals. In addition to experimentally demonstrating its practical feasibility, the previously developed analytical model is further modified to be capable of accurately predicting its hysteretic behavior. The numerical predictions by using the modified analytical model present a good match of the shaking table test results. Afterward, several sloped rolling-type bearings designed with linearly variable damping force are numerically compared with a bearing designed with conventional constant damping force. The initial friction damping force adopted in the former is designed to be smaller than the constant one adopted in the latter. The numerical comparison results indicate that when the horizontal isolation displacement does not exceed the designed turning point (or practically when subjected to minor or frequent earthquakes that seldom have a great displacement demand for seismic isolation), the linearly variable damping force design can exhibit a better acceleration control performance than the constant damping force design. In addition, the former, in general, advantages the re-centering performance over the latter. However, the maximum horizontal displacement response of the linearly variable damping force design, in general, is larger than that of the constant damping force design. It is particularly true when undergoing a horizontal isolation displacement response smaller than the designed turning point and designing a smaller value of initial friction damping force.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.8
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• pp.157-163
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• 2001

This paper presents the new linear notion device so called \"inch-werm\" which gets large displacement by incrementally summing small displacements of PZT actuators. Dynamic stiffness of inch-worm is generally low compared to its driving condition due to the requirement of inch-worm like small size and light weight. This low stiffness may degenerate the positional precision of inch-worm. An inch-worm is realized using three PZT actuators, a monolithic moving device and a guide way frame. Finite element method and experimental approach are used to analyse the static and dynamic motion of the designed inch-worm. Command reference input is shaped to reduce the residual vibration of inch-worm. The practical feasibility of inch-worm is also examined by running tests.ing tests.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.2
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• pp.86-95
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• 2001

Mechanical properties of electroplated gold microstructures were determined from the micromachined beam structures. Cantilever and bridge beam structures of different length were fabricated by electroplating-surface micromachining technique, which is specially designed to realize an anchor structure close to an ideal fixed-boundary condition. Fabricated beams were electrostatically excited and their resonance frequencies were measured by optical system composed of laser displacement meter with dynamic signal analyzer. Young's modulus and mean residual stress were calculated from the measured frequencies of microbeams. In addtion, stress gradient was measured using deformation of released cantilever beam structure.