• 대한기계학회논문집A
• /
• 제24권2호
• /
• pp.303-310
• /
• 2000

Fracture toughness of five different reactor pressure vessel steels was characterized in the transition temperature region by the ASTM E1921-97 standard method using Charpy-sized small specimens. T he predominant fracture mode of the tested steels was transgranular cleavage in the test conditions. A statistical analysis based on the Weibull distribution was applied to the interpretation of the scattered fracture toughness data. The size-dependence of the measured fracture toughness values was also well predicted by means of the Weibull probabilistic analysis. The measured fracture toughness transition curves followed the temperature-dependence of the ASTM master curve within the expected scatter bands. Therefore, the fracture toughness characteristics in the transition region could be described by a single parameter, so-called the reference temperature (T。), for a given steel. The determined reference temperatures of the tested materials could not be correlated with the conventional index temperatures from Charpy impact tests.

• 한국임상약학회지
• /
• 제29권3호
• /
• pp.147-155
• /
• 2019

Objectives: The purpose of this study was to investigate the association between fracture risk and proton pump inhibitor (PPI) use to establish evidence for defining high-risk groups of fracture among PPI users. Methods: A case-control study was performed using the National Health Insurance Sample Cohort Database from January 2002 to December 2013. The cases included all incidences of major fractures identified from January 2011 to December 2013, and up to four controls were matched to each case by age, gender, osteoporosis, and Charlson comorbidity index. Conditional logistic regression was used to calculate the adjusted odds ratio (aOR) and associated 95% confidence interval (CI). Results: Overall, 14,295 cases were identified, and 63,435 controls were matched to the cases. The aOR of fractures related to the use of PPIs was 1.06 (95% CI: 1.01-1.11). There was a statistically significant association between fracture and PPI use within 3 months of the last dose, and a trend of increasing fracture risk with increasing cumulative PPI dose. The risk of fracture was significantly higher in patients who took PPIs for more than 1 year during the 2-year observation period. Conclusion: Patients who have been using PPIs for more than 1 year should be warned about the risk of fracture during or at least 3 months after discontinuing the PPI.

• Clinics in Shoulder and Elbow
• /
• 제20권4호
• /
• pp.195-200
• /
• 2017

Background: This study investigated and evaluated the clinical outcomes of intra-articular lesions of traumatic anterior shoulder dislocation (TASD) associated with greater tuberosity (GT) fracture of the humerus. Methods: Subjects included 20 patients who were surgically or non-surgically treated for GT fracture of the humeurs with TASD, and followed-up for at least 2 years. The mean follow-up period was 54.1 months (range, 24-105 months). Of the 20 patients, 12 were treated surgically. Intra-articular lesions were identified randomly on magnetic resonance imaging scans (repeated thrice) by experienced radiologists and orthopedic surgeons. The accompanying intra-articular lesions were left untreated. Clinical outcomes were evaluated by Simple Shoulder Test (SST) and Western Ontario Shoulder Instability index (WOSI) at the last follow-up. Results: Intra-articular lesions were identified in 19 patients: 7 Bankart lesions, 15 humeral avulsion of the glenohumeral ligament lesions, 3 glenoid avulsion of the glenohumeral ligament lesion, and 6 inferior capsular tears. Two or more intra-articular lesions were identified in 6 patients. The mean SST score was 10.9 and the mean WOSI score was 449.3 at the last follow-up. Conclusions: For GT fracture of the humerus with TASD, a high frequency of diverse intra-articular lesions was identified. There were no incidence of recurrent shoulder dislocations, and good clinical outcomes were obtained without treatment of the intra-articular lesions. We thereby comprehend that although intra-articular lesions may occur in TASD associated with GT fracture of the humeurs, merely treating the GT fracture of the humerus is sufficient.

• 한방재활의학과학회지
• /
• 제28권2호
• /
• pp.135-148
• /
• 2018

The objective of this study is to investigate conservative treatment of pelvic fracture, and report that Korean rehabilitation treatment is effective for pelvic fracture. We reported a case about pelvic fracture treated with Korean rehabilitation treatment. We searched 10 domestic electronic databases to find reports on conservative treatment of pelvic fracture. We selected and analyzed 12 studies. In this case, pain, range of motion, and Oswestry Disability Index of patient were improved by Korean rehabilitation treatment. In analysis, traction, pelvic sling, hip spica cast, pelvic belt, medication are used in western medical treatment. Acupuncture, herbal medicine, cupping, moxibustion, physical therapy, manual therapy are used in Korean medical treatment. Most of conservative treatments are effective for pain, bone union, osteoporosis, dysfunction. In this study, we expect further study of Korean rehabilitation treatment program for pelvic fracture to compensate existing conservative treatment.

• Structural Engineering and Mechanics
• /
• 제26권3호
• /
• pp.315-341
• /
• 2007

A sudden change of stiffness in a structure, associated with the events such as weld fracture and brace breakage, will cause a discontinuity in acceleration response time histories recorded in the vicinity of damage location at damage time instant. A new damage index is proposed and implemented in this paper to detect the damage time instant, location, and severity of a structure due to a sudden change of structural stiffness. The proposed damage index is suitable for online structural health monitoring applications. It can also be used in conjunction with the empirical mode decomposition (EMD) for damage detection without using the intermittency check. Numerical simulation using a five-story shear building under different types of excitation is executed to assess the effectiveness and reliability of the proposed damage index and damage detection approach for the building at different damage levels. The sensitivity of the damage index to the intensity and frequency range of measurement noise is also examined. The results from this study demonstrate that the damage index and damage detection approach proposed can accurately identify the damage time instant and location in the building due to a sudden loss of stiffness if measurement noise is below a certain level. The relation between the damage severity and the proposed damage index is linear. The wavelet-transform (WT) and the EMD with intermittency check are also applied to the same building for the comparison of detection efficiency between the proposed approach, the WT and the EMD.

• 한국압력기기공학회 논문집
• /
• 제12권2호
• /
• pp.50-57
• /
• 2016

The study presents structural integrity assessment of ductility degradation of a baffle former assembly by performing finite element analysis considering real loading conditions and stress triaxiality. Variations of fracture strain curves of type 304 austenitic stainless steel with stress triaxiality are derived based on the previous study results. Temperature distributions during normal operation such as heat-up, steady state, and cool-down are calculated via finite element temperature analysis considering gamma heating and heat convection with reactor coolant. Variations of stress and strain state during long operation period are also calculated by performing sequentially coupled temperature-stress analysis. Fracture strain is derived by using the fracture curve and the stress triaxility. Finally, variations of ductility degradation damage indicator with the fracture strain and the equivalent inelastic strain are investigated. It is found that maximum value of the ductility degradation damage index continuously increases and becomes 0.4877 at 40 EFPYs. Also, the maximum value occurs at top and middle inner parts of the baffle former assembly before and after 20 EFPYs, respectively.

• Computers and Concrete
• /
• 제4권3호
• /
• pp.207-220
• /
• 2007

In this paper, hybrid fibers including high elastic modulus steel fiber and low elastic modulus synthetic macro-fiber (HPP) as two elements were used as reinforcement materials in concrete. The flexural toughness, flexural impact and fracture performance of the composites were investigated systematically. Flexural impact strength was analyzed with statistic analyses method; based on ASTM and JSCE method, an improved flexural toughness evaluating method suitable for concrete with synthetic macro-fiber was proposed herein. The experimental results showed that when the total fiber volume fractions ($V_f^a$) were kept as a constant ($V_f^a=1.5%$), compared with single type of steel or HPP fibers, hybrid fibers can significantly improve the toughness, flexural impact life and fracture properties of concrete. Relative residual strength RSI', impact ductile index ${\lambda}$ and fracture energy $G_F$ of concrete combined with hybrid fibers were respectively 66-80%, 5-12 and 121-137 N/m, which indicated that the synergistic effects (or combined effects) between steel fiber and synthetic macro-fiber were good.

• 대한토목학회논문집
• /
• 제11권3호
• /
• pp.19-27
• /
• 1991

본 논문에서는 강섬유보강콘크리트 구조물의 파괴거동을 규명하기 위하여 파괴실험을 수행하였다. 실험대상 시험체는 모두 36개였으며, 실험시 시험체의 하중의 변화에 대한 휨 변형률과 중앙처침량의 변화를 관찰하였다. 이들 결과를 토대로, 강섬유 혼입량, 강섬유 형상비와 초기균열비의 변화에 대한 강섬유보강콘크리트의 파괴거동을 고찰하였으며, 강섬유보강콘크리트의 울력확대계수, 인성지수, 휨강도를 계산 비교하였다. 아울러 회귀분석에 의하여 강섬유보강콘크리트의 휨강도를 예측할 수 있는 예측공식을 유도하였다.

• 화약ㆍ발파
• /
• 제26권1호
• /
• pp.57-66
• /
• 2008

발파에서 특정한 방향으로 균열 성장을 제어하는데 장약공 노치가 유효하다는 연구결과가 발표되어오고 있다. 본 연구에서는 장약공의 노치가 파단면 형성에 미치는 영향을 살펴보기 위하여 일반 장약공과 노치 장약공에 의한 파단면의 표면을 비교하였다. 암석시편에 노치를 형성하기 위하여 노치비트시스템이 적용되었다. 파단면의 표면은 디지털 영상 계측법을 적용하여 DEM 모델로 재구성하고, 표면 거칠기 지수를 사용하여 파단면의 거칠기를 평가하였다.

• 펄프종이기술
• /
• 제46권3호
• /
• pp.81-87
• /
• 2014

Conditions of paper manufacturing process should be changed depending on the end use and paper properties. Most of the case, mixed pulps with long softwood fibers and short hardwood fibers are used to achieve proper qualities of product with reasonable production cost. For specialty paper manufacture the wood pulp and cotton linter pulp are usually mixed together. The objectives of this study is to analyze physical, mechanical and fracture mechanical properties of paper depending on SwBKP, HwBKP and cotton linter pulp(CLP) mixing. When the mixing ratio of SwBKP was increased, strength properties, such as tensile, tear, and folding endurance, were also increased. When the mixing ratio of SwBKP and HwBKP was increased, stress concentration index was decreased and fracture toughness was increased.