• Geomechanics and Engineering
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• 제5권5호
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• pp.463-483
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• 2013

Considering the influences of fluid penetration, casing, excavation processes of wellbore and perforation tunnels, the seepage-deformation finite element model of oil and gas well coupled with perforating technique is established using the tensile strength failure criterion, in which the user-defined subroutine is developed to investigate the dynamic evolvement of the reservoir porosity and permeability. The results show that the increases of perforation angle and decreases of perforation density lead to a higher fracture initiation pressure, while the changes of the perforation diameter and length have no evident influences on the fracture initiation pressure. As for initiation location for the fracture in wellbore, it is on the wellbore face while considering the presence of the casing. By contrast, the fractures firstly initiate on the root of the tunnels without considering casing. Besides, the initial fracture position is also related with the perforation angle. The fracture initiation position is located in the point far away from the wellbore face, when the perforation angle is around $30^{\circ}$; however, when the perforation angle is increased to $45^{\circ}$, a plane fracture is initiated from the wellbore face in the maximum horizontal stress direction; no fractures was found around perforation tunnels, when the angel is close to $90^{\circ}$. The results have been successfully applied in an oilfield, with the error of only 1.1% comparing the fracture initiation pressure simulated with the one from on-site experiment.

• 대한족부족관절학회지
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• 제14권2호
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• pp.119-122
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• 2010

Purpose: One of the main contributors to proximal fifth metatarsal fracture is ankle inversion and the incidence of recurrence may increase in patients with ankle instability. So, the authors confirmed the patients of proximal fifth metatarsal fracture with ankle instability by checking the history and magnetic resonance imaging (MRI) and assessed the value of MRI as therapeutic prognosis and clinical indicators for prevention of recurrence. Materials and Methods: Patients with proximal fifth metatarsal fractures visited our hospital during recent five years were reviewed. 35 patients with suspected damage by ankle inversion had been identified a history of ankle instability and checked the hindfoot malalignment through hindfoot alignment view and MRI was performed prospectively. The patients was devided to three groups on the location of fracture site and the groups were compared each other. Results: The mean time from injury to checking MRI was 10.7 days. There was no structural abnormality and was no significant difference according to the location of fracture. The patients with history of ankle inversion were 31(88.6%) and the patients with history of chronic or recurrent injury were 22 patients (62.9%). The lesion of MRI related to lateral ankle instability were identified in all patients. Conclusion: This study noted a high incidence of lateral ankle instability that was identified by MRI in the patients of proximal fifth metatarsal fracture. Aggressive treatment for lateral ankle instability should be needed for complications as proximal fifth metatarsal fracture to reduce the recurrence and occurrence.

• 대한두개안면성형외과학회지
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• 제9권1호
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• pp.17-22
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• 2008

Purpose: For several decades, open reduction has been a controversial issue in mandibular condyle fracture. The authors have successfully used the open reduction and internal fixation with retromandibular approach and have found it to be satisfactory for mandibular condyle fracture. Methods: A total of 10 patients with mandibular condyle fracture underwent open surgical treatment using retromandibular approach. The incision for the retromandibular approach was carried below the ear lobe and the facial nerve branches were identified. Dissection was continued until the fracture site was exposed and internal fixation was performed with miniplate following intermaxillary fixation. The average period of joint immobilization was 1 weeks and the arch bars were removed in 3 weeks on average. The preoperative and postoperative panoramic view and three-dimensional computed tomography were compared. During the follow up period, we evaluated the presence of malocclusion, chin deviation, trismus, pain, click sound, facial nerve palsy, hypertrophic scar and skin fistula. Results: According to the radiographic findings, the fractured condyle was reducted satisfactorily in all patients without any symptoms of facial palsy. During the follow up period ranged form 6 to 12 months, all clinical symptoms were improved except in one case with chin deviation and malocclusion. Conclusion: Using open reduction and internal fixation of mandibular condyle fracture with retromandibular approach, all results were satisfactory with good functional outcomes and minimal complication. We concluded that the open surgical treatment should be considered as the first choice for mandibular condyle fracture management.

• 한방재활의학과학회지
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• 제30권4호
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• pp.17-30
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• 2020

Objectives The purpose of this study is to evaluate the healing effect of Yukmijihwang-tang (YM) on femur fractured mice. Methods Mice were randomly divided into 6 groups: normal, control, positive control, YM with low, medium, high dosage each. All groups were prepared with femur fracture and treated diffrently. In order to measure bone regeneration effects, we analysed the levels of cyclooxygenase-2 (COX2), bone morphogenetic protein-2 (BMP2), collagen type II alpha 1 chain (Col2a1), Sox9, runt-related transcription factor 2 (Runx2), and osterix genes expressed in bone. For morphological analysis, muscles were removed and femur was observed with naked eye. Results COX2 gene expression in bone marrow significantly decreased. BMP2 gene expression significantly increased. Col2a1 gene expression significantly increased. Sox9 gene expression increased as well. Runx2 gene expression in bone marrow increased, but there was no statistical significance. Osterix gene expression significantly increased. Union of the fracture site progressed more in YM group compared to the control group. The fracture union score was significantly decreased in YM group compared to the control group. Conclusions YM showed anti-inflammatory effect, promoted bone regeneration by stimulating the bone regeneration factor. In conclusion, YM can help fracture healing and it well be applied clinically to patients with fracture.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제48권2호
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• pp.94-100
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• 2022

Objectives: This study aimed to compare the effects of systemic administration of levofloxacin or cephalexin on fracture healing in rats. Materials and Methods: In this animal study, tibial fractures not requiring fixation were artificially induced in 30 male Wistar albino rats using a 1.1 mm surgical bur. The rats were randomly divided into 6 groups (n=5). Groups 1 and 2 received daily subcutaneous saline injections. Groups 3 and 4 received subcutaneous injections of 25 mg/kg levofloxacin twice daily. Groups 5 and 6 received daily subcutaneous injections of 20 mg/kg cephalexin. The rats in Groups 1, 3, and 5 were sacrificed after 1 week, while the rats in Groups 2, 4, and 6 were sacrificed after 4 weeks. The score of fracture healing was determined through histological assessment of sections from the fracture site according to Perry and colleagues. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests. Results: The mean score of fracture healing at 4 weeks was significantly higher than that at 1 week in the saline, levofloxacin, and cephalexin groups (P<0.001). At 1 week, no significant difference was noted among the three groups of saline, levofloxacin, and cephalexin in the mean score of fracture healing (P=0.360). However, this difference was significant at 4 weeks (P=0.018), and the mean score in the saline group was significantly higher compared to that in the levofloxacin group (P=0.015). Conclusion: It is recommended not to prescribe levofloxacin for more than 1 week after surgical management of bone fractures due to its possible adverse effects on fracture healing.

• Geomechanics and Engineering
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• 제30권6호
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• pp.503-515
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• 2022

The permeability coefficient is an essential parameter for the study of seepage flow in fractured rock mass. This paper discusses the feasibility and application value of using readily available RQD (rock quality index) data to estimate mine water inflow and grouting quantity. Firstly, the influence of different fracture frequencies on permeability in a unit area was explored by combining numerical simulation and experiment, and the relationship between fracture frequencies and pressure and flow velocity at the monitoring point in fractured rock mass was obtained. Then, the stochastic function generation program was used to establish the flow analysis model in fractured rock mass to explore the relationship between flow velocity, pressure and analyze the universal law between fracture frequency and permeability. The concepts of fracture width and connectivity are introduced to modify the permeability calculation formula and grouting formula. Finally, based on the on-site grouting water control example, the rock mass quality index is used to estimate the mine water inflow and the grouting quantity. The results show that it is feasible to estimate the fracture frequency and then calculate the permeability coefficient by RQD. The relationship between fracture frequency and RQD is in accordance with exponential function, and the relationship between structure surface frequency and permeability is also in accordance with exponential function. The calculation results are in good agreement with the field monitoring results, which verifies the rationality of the calculation method. The relationship between the rock mass RQD index and the rock mass permeability established in this paper can be used to invert the mechanical parameters of the rock mass or to judge the permeability and safety of the rock mass by using the mechanical parameters of the rock mass, which is of great significance to the prediction of mine water inflow and the safety evaluation of water inrush disaster management.

• 지질공학
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• 제9권1호
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• pp.31-43
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• 1999

본 연구는 여수반도 북동부지역에서의 단열망 개념의 지하수유동 수치해석에 필요한 단열계의 분포특성에 대하여 여러 가지 방법을 통하여 이를 조사, 분석하는데 목적이 있다. 연구지역의 지질은 크게 화산암류와 화강암으로 구분된다. Order 1∼Order 3등급에 해당되는 광역 및 부지규모의 선상구조는 기존 지질도, 항공사진 및 전산음영기복도를 이용하여 분석되었다. Order 4등급의 단열계에 대한 자료는 지표에서 측선조사를 통하여 이루어졌다. Order 4등급의 단열계에서 저경사각의 Set 4의 방향이 선상구조에서는 두드러지지 않은 점을 제외하고는 전체적으로 유사한 분포양상을 갖는다. Order 4등급의 단열계는 3개의 고경사각 단열조와 1개의 저경사각 단열조로 분류되며, 암종별 뚜렷한 차이는 보이지 않는다. Set 1부터 Set 4의 순서대로 발달 정도가 체계적이며, 충전물질은 상대적으로 저경사각 단열조에 우세한 경향을 보인다. 단열간격은 대수정규분포를 따르고, 수정 Terzaghi 보정을 적용하였을 때 단열조별 단열의 빈도는 0.38/m∼1.01/m의 범위를 갖는다. 단열 길이 역시 대수정규분포를 따르고, 단열조별 평균치는 2.9m∼3.7m의 범위를 갖는다.

• 한국주조공학회지
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• 제37권6호
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• pp.199-206
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• 2017

In this study, the variations of microstructures and tensile properties of Ti-(44-54)at.%Al binary alloys were investigated. The heat-treated microstructure depended greatly on their solidification structure and annealing temperature. We measured the variations of volume fractions of primary and secondary lamellar structure as a function of the heat treatment temperature in a Ti-47at.%Al alloy. The variation of ductility as a function of Al content was in good agreement with the change of fracture mode in the tensile fracture surface. It can be inferred that the variations of yield stress and hardness of ${\gamma}$ phase in a single ${\gamma}$-phase field region are enhanced by anti-site defects created by deviations from the stoichiometric composition. In a Ti-47at.%Al alloy within the (${\alpha}_2+{\gamma}$) two-phase field, the yield stress tended to be the maximum at a near equal volume fraction of lamellar and ${\gamma}$ grains. The ductility depended sensitively on the overall grain size and Al content. The calculation of fracture strain using Chan's model indicated that the change of ductility as a function of annealing temperature was primarily determined by the variations in the overall grain size and lamellar volume fraction.

• 한국정밀공학회지
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• 제17권4호
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• pp.22-28
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• 2000

By using the finite element method, the Oyane's ductile fracture integral I was calculated from the histories of stress and strain according to every element and then the forming limit of hydroforming process could be evaluated. The fracture initiation site and the forming limit for two typical hydroforming processes, tee extrusion and bumper rail under different forming conditions are predicted in this study. For tee extrusion hydroforming process, the pressure level has significant influence on the forming limit. When the expansion area is backed by a supporter and bulged, the process would be more stable and the possibility of bursting failure is reduced. For bumper rail, the ductile fracture integral i is not only affected by the process parameters, but also by the shape of preforming blank. Due to no axial feeding on the end side of the blank, the possibility of cracking in hydroforming of the bumper rail is influenced by the friction condition more strongly than that of the tee extrusion. All the simulation results show reasonable plastic deformation, and the applications of the method could be extended to a wide range of hydroforming processes.

• 대한한의학회지
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• 제41권3호
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• pp.151-161
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• 2020

Objectives: The purpose of this study is to report the improvement of multiple rib fracture after korean medical treatment; adhesive treatment and herb-medicine treatment. Methods: A patient with multiple rib fracture was treated with Daewhangchija-paste(大黃梔子膏) adhesive and herb-medicine treatment. Verbal numeric rating scale, medical examination by interview and rib series x-ray were used to assess progress of treatment. And we took pictures of left flank after attaching Daewhangchija-paste to observe the changes of the skin colors. Results: Rib series x-ray taken after 2 months of treatment revealed hard callus which added stability against external force on rib cage. After taking off Daewhangchija-paste, left plank skin turned into blue, green and yellow. And the pain level(VNRS) of left plank decreased from 10 to 0.5 for 4 months. Conclusions: Pain reduction on trauma site and improvement of general health condition were observed during combination treatment of Daewhangchija-paste adhesive and herb-medicine.