• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.881-888
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• 1997

A new algorithm for detection of tool fracture in milling process was developed. The variation of the peak-to-valley value of cutting load was used in this algorithm. Various kinds of vectors representing the condition of tool, such as tool condition vector, reference tool condition vector, tool condition variation vector were defined. Using these vectors, tool fracture index which represents the magnitude of tool fracture and is independent of tool run-outs is developed. Small and large tool fracture and chipping under various cutting condition could be detected using proposed tool fracture index, which was proved with cutting force model and experiments.

• Journal of the Korean Society for Railway
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• v.8 no.3
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• pp.210-215
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• 2005

The safety evaluations of railway wheelsets make use of the static fracture toughness obtained in ingot materials. The static fracture toughness of wheelset materials has been extensively studied by experiments, but the dynamic fracture toughness with respect to wheelset materials has not been studied enough yet. It is necessary to evaluate the characteristics of the fracture mechanics depending on each location for a full-scale wheelset for high-speed trains, because the load state for each location of the wheelset while running is different the contact load between the wheel and rail, cyclic stress in the wheel plate, etc. This paper deals with the fracture toughness depend on load rates. The fracture toughness depending on load rate data shows that once the downward curve from quasi-static values was reached, subsequent values showed a slow increase with respect to the impact velocity. This means that dynamic fracture toughness should be considered in the design code of the wheelset material.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2006.06a
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• pp.3-8
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• 2006

The integrity of laser welded structures is decided with fracture strength and fatigue strength. This study presents fracture behavior considering residual stress in the laser welding. Experiments are conducted and analyses are performed to explore the influence of residual stress on fracture behavior of bead-on laser welded compact specimen. Fracture experiments are performed using ASTM 1820. The performed analyses included thermo-elasto-plastic analyses for residual stress and subsequent J-integral calculation. A modified J integral is calculated in the presence of residual stresses. The J-integral is path-independent for combination of residual stress field and stress due to mechanical loading. The results indicates that the tensile residual stress near crack front bring the low fracture load while the compressive residual stress bring the high fracture load compared to no residual stress specimen. These results quantitatively understand the influence of residual stress on fracture behavior.

• Laser Solutions
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• v.11 no.2
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• pp.1-7
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• 2008

The integrity of laser welded structures is decided in fracture strength and fatigue strength. This study made an effort to understand the fracture behavior considering residual stress. Experiments are conducted and analyses are performed to explore the influence of residual stress on fracture behavior of bead-on laser welded compact specimen. Fracture experiments are performed using ASTM 1820. The performed analyses included thermo-elasto-plastic analyses for residual stress and subsequent J-integral calculation. A modified J integral is calculated in the presence of residual stresses. The J-integral is path-independent for combination of residual stress field and stress due to mechanical loading. The results indicates that the tensile residual stress near crack front bring the low fracture load while the compressive residual stress bring the high fracture load compared to no residual stress specimen. These results quantitatively understand the influence of residual stress on fracture behavior.

• Advances in concrete construction
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• v.5 no.6
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• pp.613-624
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• 2017

In this paper, an experimental investigation was carried out to study the effect of volume fraction of fiber and maximum aggregate size on mode-I fracture parameters of high strength concrete. Total of 108 beams were tested on loading frame with three point loading, the variables in the high strength concrete beams are aggregate size (20 mm, 16 mm and 10 mm) and volume fraction of fibers (0%, 0.5%, 1% and 1.5%). The fracture parameters like fracture energy, brittleness number and fracture process zone were analyzed by the size effect method (SEM). It was found that fracture energy (Gf) increases with increasing the Maximum aggregate size and also increasing the volume of fibers, brittleness number (${\beta}$) decreases and fracture process zone (CF) increases.

• Archives of Craniofacial Surgery
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• v.20 no.4
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• pp.219-222
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• 2019

The purpose of this study is to discuss several approaches to addressing naso-orbito-ethmoidal (NOE) fracture. Orbital fracture, especially infraorbital fracture, can be treated through the transconjunctival approach easily. However, in more severe cases, for example, fracture extending to the medial orbital wall or zygomatico-frontal suture line, only transconjunctival incision is insufficient to secure good surgical field. And, it also has risk of tearing the conjunctiva, which could injure the lacrimal duct. Also, in most complex types of facial fracture such as NOE fracture or panfacial fracture, destruction of the structure often occurs, for example, trap-door deformity; a fracture of orbital floor where the inferiorly displaced blowout facture recoils to its original position, or vertical folding deformity; fractured fragments are displaced under the other fragments, causing multiple-packed layers of bone.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.18 no.3
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• pp.454-462
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• 1996

With the increase of population, dramatic urbanization, traffic, leisure and sports, the number of maxillofacial injury has increased markedly. Subsequently the number of motor vehicle accident, sports accident and industrial accident were increased and the number of oral and maxillofacial trauma patients were also markedly increased. A clinical study on 177 patients with facial bone fracture who visited Kangnam General Hospital during 4 years(1992-1995) was done by analysing sex, cause, fracture site, treatment method, complication and involvement of other body part. The results obtained were as follows : 1. The occurrence was more frequent in male than in female with the ratio of 4.2 : 1 and most frequently in twenties. 2. Violence was the most common cause of facial bone fracture. 3. Mandible was the most frequently occurred site and there were more cases of simple fracture(81.9%) than cases of compound fracture. 4. Simple fracture was most frequently occurred(44.0%). 5. In mandible fracture, simple fracture was 86.1%, fracture site was average 1.5 sites, most frequently in symphysis. 6. As treatment methods, open reduction(78.5%) was used more frequently than closed reduction(21.5%). 7. Post-operative complication occurred in 29.4% of the cases. 8. Other injuries that were related to maxillofacial fracture occurred in 28.2%.

• Journal of the Korean Wood Science and Technology
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• v.18 no.3
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• pp.6-16
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• 1990

The objectives of this study were to investigate the relative effects of specific gravity and particle size on internal bond and tensile strengths and fracture toughness of particleboard and to compare mechanical strength with fracture toughness. The particleboard was manufactured with three different particle sizes at specific gravity levels of 0.6, 0.7, and 0.8 with a resin content of 10% based on oven dry weight. The results were summarized as follows: 1. Internal bond strength. fracture toughness in internal bond test. maximum tensile strength, and fracture toughness in tension test increased with the increase of specific gravity of particleboard. 2. As partcle size increased, internal bond strength, fracture toughness. maximum tensile strength. and fracture toughness in tension test increased. 3. The maximum tensile strength and fracture toughness appeared to be in a direct relationship, and then maximum tensile strength could be used for predicition of fracture toughness for tension test. 4. The fracture toughness in internal bond test was somewhat independent on induced crack length.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.99-104
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• 1994

Recently, nonlinear fracture mechanics was applied to analyze concrete structures more accurately, and new materials property such as fracture energy(Gf) was used for its application. The fracture energy was influenced by many parameters, especially the strength of concrete. Many researches on the relation between the strength of concrete and the fracture energy were performed. In spite of many researches on the relation between the strength of concrete and the fracture energy, there is no distinct conclusion. This research includes various the strength levels from low-strength of concrete to high-strength, and then intends to estimate relation between the strength of concrete and the fracture energy. Concrete used crushed sand is also included, which is going to be used much. In this research, the wedge splitting test method proposed by Prof. Linsbauer is adopted to investigate the fracture energy. Fracture behavior of concrete used natrual sand and crushed sand has the similar trend. In the strength range of 200~500 kg/$\textrm{cm}^2$, the fracture energy and the maximum splitting forces(F) increase as the strength of concrete increases. In the range of the higher strength, however, the maximum splitting forces(F) increases but the fracture energy decreases as the strength of concrete increases. Through this investigation the fracture energy of concrete was not proportional to the strength of concrete.

• Journal of Ocean Engineering and Technology
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• v.34 no.3
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• pp.155-166
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• 2020

Ductile fracture prediction is critical for the reasonable damage extent assessment of ships and offshore structures subjected to accidental loads, such as ship collisions and groundings. A fracture model combining the Hosford-Coulomb ductile fracture model with the domain of solid-to-shell equivalence model (HC-SDDE), was used in fracture simulations based on shell elements for the punching fracture experiments of unstiffened and stiffened panels. The flow stress and ductile fracture characteristics of JIS G3131 SPHC steel were identified through tension tests for flat bar, notched tension bar, central hole tension bar, plane strain tension bar, and pure shear bar specimens. Punching fracture tests for unstiffened and stiffened panels are conducted to validate the presented HC-DSSE model. The calibrated fracture model is implemented in a user-defined material subroutine. The force-indentation curves and final damage extents obtained from the simulations are compared with experimental results. The HC-DSSE fracture model provides reasonable estimations in terms of force-indentation paths and residual damage extents.