• Transactions of Materials Processing
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• v.32 no.3
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• pp.129-135
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• 2023

The use of engineering plastic products in internal combustion engine and electric cars to improve stiffness and reduce weight is increasing significantly. Among various lightweight materials, engineering plastics have significant advantages such as cost reduction, improved productivity, and weight reduction. In particular, engineering plastics containing glass fibers are used to enhance stiffness. However, the stiffness of glass fibers can increase or decrease depending on their orientation. Before developing plastic products, optimal designs are determined through injection molding and structural analysis to enhance product reliability. However, reliable analysis of products with variable stiffnesses caused by anisotropy cannot be achieved via the conventional isotropic structural analysis, which does not consider anisotropy. Therefore, based on the previously reported study "the Effect of Impacted Fracture in Glass Fiber Orientation with Injection Molding & Structural Coupled Analysis," this study aims to investigate the structural analysis and degradation mechanisms of various polymers. In particular, this study elucidates the actual mechanism of plastic fracture by analyzing various fracture conditions and their corresponding simulations. Furthermore, the objective of this study is to apply the injection molding and structural coupled analysis mechanism to develop engineering plastic products containing glass fibers. In addition, the study aims to apply and improve the plastic fracture mechanism in actual products by exploring anisotropy and stiffness reduction owing to the unfilled polymer weld line.

• Journal of the Korean GEO-environmental Society
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• v.10 no.6
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• pp.125-133
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• 2009

Rock fracturing technique through fluid injection into the wellbore has been widely used to extract geothermal heat and to enhance oil and gas production. Single fracture formation is ideal for the production. However, it is very difficult to form single fracture formation. Instead, the formation of segmented fracture is a common phenomenon. Therefore, design parameters are expected to be different from those of single fracture because of mechanical interaction between segmented fractures. In this paper, design parameters such as length, aperture, and net pressure are evaluated by using model of segmented fracture in which numerical technique is incorporated to consider mechanical interaction between segments. Results show that the existence of fracture segmentation affects design parameters in fracturing treatment in rock by fluid injection.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.40
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• pp.36.1-36.5
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• 2018

Background: Botulinum toxin-A (BTX-A) injection into muscle reduces muscular power and may prevent post-operative complication after orthognathic surgery. The purpose of this study was (1) to evaluate BTX-A injection into the masseter muscle on the prevention of plate fracture and (2) to compare post-operative relapse between the BTX-A injection group and the no injection group. Methods: Sixteen patients were included in this study. Eight patients received BTX-A injection bilaterally, and eight patients served as control. All patients received bilateral sagittal split ramus osteotomy for the mandibular setback and additional surgery, such as LeFort I osteotomy or genioplasty. Post-operative plate fracture was recorded. SNB angle, mandibular plane angle, and gonial angle were used for post-operative relapse. Results: Total number of fractured plates in patients was 2 out of 16 plates in the BTX-A injection group and that was 8 out of 16 plates in the no treatment group (P = 0.031). However, there were no significant differences in post-operative changes in SNB angle, mandibular plane angle, and gonial angle between groups (P > 0.05). Conclusions: BTX-A injection into the masseter muscle could reduce the incidence of plate fracture.

• Journal of Veterinary Science
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• v.21 no.6
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• pp.90.1-90.11
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• 2020

Background: Mandibular fractures are common in camels, leading to considerable economic losses. This study explored methods of improving mandibular fractures repair, adjuvant with interdental wire, or bone plate fixation. Autologous bone marrow (BM) injection enhances osteogenesis and rapid healing. Objectives: To investigate the effect of autologous BM aspirate as an adjuvant treatment for repairing mandibular fractures in camels with interdental wire, or bone plate fixation. Methods: Thirty dromedary camels aged 5-8 years and of both sexes were randomly divided into 4 treatment groups: group 1 (n = 10) treated with stainless steel wire fixation and BM injection at the fracture line, group 2 (n = 10) treated with plate fixation and BM injection at the fracture line, group 3 (n = 5) treated with stainless steel bone wire fixation and placebo saline injection at the fracture line, and group 4 (n = 5) treated with plate fixation and placebo injection at the fracture line. The mandibular fractures were followed weekly for 12 weeks postoperatively to assess improvement and healing based on clinical evaluation, radiographic union scale, and bone turnover markers (i.e., bone alkaline phosphatase, osteocalcin, pyridinoline, and deoxypyridinoline). Results: Compared to other groups, elevated bone turnover markers in group 1 were demonstrated (p < 0.05) on the seventh postoperative day. Likewise, compared to other groups, both clinical findings and radiographic union scale significantly improved (p < 0.05) in group 1 on the 56th postoperative day. Conclusions: BM aspirate has a promising beneficial osteogenic effect on mandibular fracture repair in camels, most notably when combined with interdental wire fixation.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.284-287
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• 2005

The flow of groundwater in fractured medium is related to the geometric characteristics of the fracture system. And a fracture aperture and a fracture density are considered as important factor concerning the permeability. Data acquisition of the properties of fracture such as aperture and density is so difficult and has uncertainty. We also cannot know the fracture characteristics through the in-situ tests. We usually obtain the fracture information from a ultrasonic scan logging or borehole television indirectly. Using the deduced results, we can make the fracture system and simulate the groundwater flow and solute transport in the crystalline rock. This study aimed to analyze the correlation between the properties of fracture and hydraulic conductivities obtained at the same interval. The properties of fracture are examined by acoustic televiwer and hydraulic conductivities are obtained by constant Pressure injection test. The distributioin of fracture width and fracture frequency shows the log-normal probability plot. And, Results of correlation analysis explain that opened type fractures have proper relation with hydraulic conductivity. But, as though there are semi-opened type fractures or closed type fractures, those have the permeable structure.

• Archives of Craniofacial Surgery
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• v.9 no.2
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• pp.67-71
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• 2008

Purpose: Orbital floor fracture has open wound to maxillary sinus and if the patient has chronic maxillary sinusitis, it may be have more risk of infection, complications. The purpose of this comparative study is to be the effectiveness of prophylactic antibiotics in orbital floor fracture with chronic maxillary sinusitis. Methods: We studied 20 patients who diagnosed as orbital floor fracture with chronic maxillary sinusitis from march, 2005 to may, 2006. Among them 16 were male, 4 were female and age was ranged from 15 to 68, average was 42. A day before operation, Prophylactic antibiotics were used to 10 patients. Prophylactic antibiotics were not used to 10 patients. We defined control group as prophylactic antibiotics injection group a day before operation. After surgery, we confined use of same antibiotic for 7 days in both group. After 6 month from surgery, we compare the degree of enophthalmos from healthy side to legion side with hertel exopthalmometry(Inami, Japan) in control group and non-prophylactic antibiotics injection group. Results: In control group, comparison of discrepancy between enophthalmic eyeball and normal eyeball with Hertel exophthalmometer was 1.1 mm and non-prophylactic antibiotics injection group was 2.1 mm. In independent sample t-test, control group was showed statistically significant difference with non-prophylactic antibiotics injection group(p=0.007). Conclusions: In orbital floor fracture with chronic maxillary sinusitis, bacteria in maxillary sinus can increase post-operative complication by infecting infraorbital soft tissue, and it is thought to be antibiotic prophylaxis is play a role in decrease in degree of enophthalmos. We feel the need to further study of prophylactic antibiotics in orbital floor fracture with chronic maxillary sinusitis.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.619-626
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• 2002

In this study, a correlation among pressure, time and quantity of injection was organized from the laboratory tests, which were executed many times representing in-situ soil conditions carefully and then it would be applied to the in-situ soil injection simulator which will be developed for optimal injection into the ground. The sort of sample soils were both sand(A specimen) and silty sand(B specimen). Injection tests were gone into operation by compaction state, injection velocity and the depth individually. In the ground improved with permeation Infection, the relation among injection pressure of the same depth, the injected quantities and time were systematic by the depth. By defining the limit range of injection pressure and quantity about the variety of a linear equation obtained from lining each of their trend, the application of laboratory injection monitoring program and the data to evaluate its realization were produced. In the ground improved with root type injection, the relation between injection pressure and the injected quantities was irregular because fracture state occurred quickly.

• Water Engineering Research
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• v.2 no.2
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• pp.123-138
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• 2001

An injection experiment was carried ut to investigate the pressure domain within which hydromechanical coupling influences considerably the hydrologic behavior of a granite rock mass. The resulting database is used for testing a numerical model dedicated to the analysis of such hydromechanical interactions. These measurements were performed in an open hole section, isolated from shallower zones by a packer set at a depth of 275 m and extending down to 840 m. They consisted in a series of flow meter injection tests, at increasing injection rates. Field results showed that conductive fractures from a dynamic and interdependent network, that individual fracture zones could not be adequately modeled as independent systems, that new fluid intakes zones appeared when pore pressure exceeded the minimum principal stress magnitude in that well, and that pore pressures much larger than this minimum stress could be further supported by the circulated fractures. These characteristics give rise to the question of the influence of the morphology of the natural fracture network in a rock mass under anisotropic stress conditions on the effects of hydromechanical couplings.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.233-244
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• 2017

We conducted hydraulic fracturing experiments on cement samples to investigate the dependency of fracture propagation on the viscosity of injection fluid and the in situ stress state. Ten cubic samples (20 cm side length) were produced using cement that was cured in water for more than one month. Samples were placed in a tri-axial compression apparatus with three independent principal stresses. An injection hole was drilled and the sample was hydraulically fractured under a constant injection rate. We measured injection pressures and acoustic emissions (AE) during the experiments, and investigated the fracture patterns produced by hydraulic fracturing. Breakdown pressures increased exponentially with increasing viscosity of the injection fluid. Fracture patterns were dependent on differential stress (i.e., the difference between the major and minor principal stresses). At low differential stress, multiple fractures oriented sub-parallel to the major principal stress axis propagated from the injection hole, and in some samples the fracture orientation changed during propagation. However, at high differential stress, a single fracture propagated parallel to the major principal stress axis. AE results show similar patterns. At low differential stress, AE source locations were more widespread than at high differential stress, consistent with the fracture pattern results. Our study suggests that hydraulic fracturing during shale gas extraction should be performed parallel to the orientation of minimum differential stress.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.6
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• pp.68-74
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• 2002

This research covers the development of axi-symmetric plastic elements for injection molding with insert steel such as high stiffness Sabot. The functional requirements of sabot are concentricity and fracture resistance about vertical and horizontal forces. For these, an analysis of characteristics of PEI(polyetherimide) polymer is performed by standard test specimen with accordance of ASTM test guidance. Moldflow analysis and simulation of injection molding process are carried out in order not only to estimate of the warpage but also to predict the characteristics of residual stresses which both product and structure of mold may have. A new vertical side injection machine and transverse mold have been constructed. Results of the measuring concentricity and fracture test after molding of sabot are satisfied to design specification over Cp $ratio{\geq}1.33$. Finally, this technique needs more research application to others axi-symmetric elements having different radius with insert steel md structure analysis from now on.