• Structural Engineering and Mechanics
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• v.34 no.4
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• pp.475-490
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• 2010

It is the intention of this study to synthesize the effects of double-edge cracks on the dynamic characteristics of a beam. The stiffness matrix is first determined for a Timoshenko beam containing two same-line edge cracks. The presented model is then developed for elements with two parallel double-sided cracks, considering the interaction between the stress fields of adjacent cracks. Finally, a finite element code is implemented, to examine the influence of depth and location of double cracks, on the natural frequencies of the damaged system.

• Journal of Ocean Engineering and Technology
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• v.20 no.4 s.71
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• pp.17-23
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• 2006

Monotonic four-point bending tests were conducted on straight pipe specimens, 102 mm in diameter with local wall thinning, in order to investigate the effects of the depth, shape, and location of wall thinning on the deformation and failure behavior of pipes. The local wall thinning simulated natural erosion/corrosion metal loss. The deformation and fracture behavior of the straight pipes with local wall thinning was compared with that of non wall-thinning pipes. The failure modes were classifiedas local buckling, ovalization, or crack initiation, depending on the depth, shape, and location of the local wall thinning. Three-dimensional elasto-plastic analyses were carried out using the finite element method. The deformation and failure behavior, simulated by finite element analyses, coincided with the experimental results.

• Journal of Trauma and Injury
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• v.31 no.3
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• pp.181-188
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• 2018

Urgent reduction is required in cases of traumatic hip dislocation to reduce the risk of avascular necrosis of the femoral head. However, in cases of femoral head fractures, the dislocated hip cannot be reduced easily, and in some cases, it can even be irreducible. This irreducibility may provoke further incidental iatrogenic fractures of the femoral neck. In an irreducible hip dislocation, without further attempting for closed reduction, an immediate open reduction is recommended. This can prevent iatrogenic femoral neck fracture or avascular necrosis of the femoral head, and save the natural hip joint.

• Geomechanics and Engineering
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• v.17 no.6
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• pp.597-606
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• 2019

Ultrasonic Time-of-Flight Diffraction (TOFD) techniques are useful methods for non-destructive evaluation of fracture characteristics. This study focuses on the reliability and accuracy of ultrasonic diffraction methods to estimate the depth of rock fractures. The study material includes three different rock types; andesite, basalt and ignimbrite. Four different ultrasonic techniques were performed on these intact rocks. Artificial near-surface fracture depths were created in the laboratory by sawing. The reliability and accuracy of each technique was assessed by comparison of the repeated measurements at different path lengths along the rock surface. The standard error associated with the predictive equations is very small and their reliability and accuracy seem to be high enough to be utilized in estimating the depth of rock fractures. The performances of these techniques were re-evaluated after filling the artificial fractures with another material to simulate natural infills.

• Journal of the Korean Institute of Gas
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• v.16 no.5
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• pp.35-40
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• 2012

To analyze the macroscopic fracture behavior as functions of the gas pipeline grade and the working environment, following analyses have been accomplished. Computer analysis of changes in fracture behaviors according to the working conditions of pipelines and Analysis of dynamic ductile fracture behaviors using the Battelle Two Curve Method. Recently, an economic and reliable pipe materials with improved performance has been needed for the severe pipeline working condition and new transporting materials. As the grade of pipe materials became higher, the possibility of dynamic ductile fracture could be increased. Therefore, the understanding of the technology to control and arrest the dynamic ductile fracture is important.

• Tunnel and Underground Space
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• v.33 no.3
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• pp.189-207
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• 2023

In the present study, the thermoshearing experiment on a rough rock fracture were modeled using a three-dimensional grain-based distinct element model (GBDEM). The experiment was conducted by the Korea Institute of Construction Technology to investigate the progressive shear failure of fracture under the influence of thermal stress in a critical stress state. The numerical model employs an assembly of multiple polyhedral grains and their interfaces to represent the rock sample, and calculates the coupled thermo-mechanical behavior of the grains (blocks) and the interfaces (contacts) using 3DEC, a DEM code. The primary focus was on simulating the temperature evolution, generation of thermal stress, and shear and normal displacements of the fracture. Two fracture models, namely the mated fracture model and the unmated fracture model, were constructed based on the degree of surface matedness, and their respective behaviors were compared and analyzed. By leveraging the advantage of the DEM, the contact area between the fracture surfaces was continuously monitored during the simulation, enabling an examination of its influence on shear behavior. The numerical results demonstrated distinct differences depending on the degree of the surface matedness at the initial stage. In the mated fracture model, where the surfaces were in almost full contact, the characteristic stages of peak stress and residual stress commonly observed in shear behavior of natural rock joints were reasonably replicated, despite exhibiting discrepancies with the experimental results. The analysis of contact area variation over time confirmed that our numerical model effectively simulated the abrupt normal dilation and shear slip, stress softening phenomenon, and transition to the residual state that occur during the peak stress stage. The unmated fracture model, which closely resembled the experimental specimen, showed qualitative agreement with the experimental observations, including heat transfer characteristics, the progressive shear failure process induced by heating, and the increase in thermal stress. However, there were some mismatches between the numerical and experimental results regarding the onset of fracture slip and the magnitudes of fracture stress and displacement. This research was conducted as part of DECOVALEX-2023 Task G, and we expect the numerical model to be enhanced through continued collaboration with other research teams and validated in further studies.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.281.3-282
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• 2002

Hwang-Chil. a natural resources of Korea. doesn't have a side effects and has excellent bone cell proliferation. We will be able to use Hwang-Chil to cure and develop various disease that require tissue regeneration. such as osteoporosis and bone fracture and be used in the orthopedic area. In this study. we observed the effect of Hwang-Chil extract and concentration on osteoblast proliferation. alkaline phosphatase(ALP) activity and calcification. (omitted)

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.117-122
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• 2005

The purpose of this study is to analyze a correlation between lithology, rock physical property and fracture zone by multiple-logging method, which includes optic borehole image, suspension type PS, resistivity, SP, natural gamma, density, caliper logging located in Ogar test area, Changsu, Pocheon-gun, Gyunggi Province. The outstanding geophysical logging responses particularly shown from lithology pattern, fracture zone, dike zone. in result, the depth of fracture zone which enable groundwater flow estimated at $67{\sim}69m$.

• Archives of Craniofacial Surgery
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• v.20 no.6
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• pp.347-353
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• 2019

Most orbital surgeons believe that it's difficult to restore the primary orbital wall to its previous position and that the orbital wall is so thin that cannot be firmly its primary position. Therefore, orbital wall fractures generally have been reconstructed by replacing the bony defect with a synthetic implant. Although synthetic implants have sufficient strength to maintain their shape and position in the orbital cavity, replacement surgery has some drawbacks due to the residual permanent implants. In previous studies, the author has reported an orbital wall restoring technique in which the primary orbital wall fragment was restored to its prior position through a combination of the transorbital and transantral approaches. Simple straight and curved elevators were introduced transnasally to restore the orbital wall and to maintain temporary extraorbital support in the maxillary and ethmoid sinus. A transconjunctival approach provided sufficient space for implant insertion, while the transnasal approach enabled restoration of the herniated soft tissue back into the orbit. Fracture defect was reduced by restoring the primary orbital wall fragment to its primary position, making it possible to use relatively small size implant, furthermore, extraorbital support from both sinuses decreased the incidence of implant displacement. The author could recreate a natural shape of the orbit with the patient's own orbital bone fragments with this dual approach and effectively restored the orbital volume and shape. This procedure has the advantages for retrieving the orbital contents and restoring the primary orbital wall to its prior position.

• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.878-888
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• 1994

In order to investigate the fracture behavior of ABS terpolymer under the tension and impact load, varing the content of rubber, molecular weight of SAN, content and kinds of lubricant, tension speed, the mechanical properties were measured and SEM pictures of fracture area were taken. Under the tension, the tensile strength increased as rubber content and lubricant content decreased, while molecular weight and tension speed increased. The deformation of area near fracture site did not occur as rubber content, tension speed and molecular weight decreased and liquid lubricant was used. And in the shape of fracture seemed phase seperation. Under the impact load, the notched izod impact strength increased as rubber content, molecular weight, ambient temperature and lubricant content increased. In the SEM picture, the strength was high white the fracture surface was small.