• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 추계 학술논문 발표대회
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• pp.38-39
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• 2013

In this study, in regard to fiber reinforced mortar mixing steel fiber and 4types of organic fiber, impact test was carried out. Because to predict fracture reduction performance with flexural, tensile strength when types of fiber were different as impact reduction performance of concrete is closely related with toughness such as flexural strength, tensile strength and fracture energy etc. As a result, enhancement of toughness by fiber reinforcement controls the spall of rear. On the other hand in case of steel fiber relatively turned up high toughness in appropriate load compared with organic fiber but in same mixing rate, impact reduction performance by projectile showed low performance due to few number of an individual of mixing.

• Clinics in Shoulder and Elbow
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• 제24권4호
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• pp.239-244
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• 2021

Background: Radial neck fracture in children is rare. This study attempted to evaluate the outcome of surgically treated patients and any associated complications. Methods: This study evaluated 23 children under 15 years of age with radial neck fracture who were treated with open reduction between 2006 and 2016 to determine their range of motion, postoperative complications, and radiographic outcomes. The results were assessed clinically using the Mayo clinic elbow performance score. Results: The mean follow-up duration for patients was 34.6 months. The average postoperative angulation was 3.6°. Hypoesthesia was reported in only 9% of patients, and none of the patients complained of postoperative pain. The postoperative X-ray results were excellent in 60% and good in 40%. No radiographic complications were identified. The elbow score was excellent in 87% and good in 13% (mean score, 96.74). There was a statistical relationship between range of motion limitations and age, degree of fracture, initial displacement, and surgical pin removal time. Conclusions: Although most patients accept the closed reduction method as a primary treatment, the present study suggests that an open-reduction approach has been associated with optimal therapeutic outcomes for patients in whom closed reduction was not satisfactory or indicated.

• Clinics in Shoulder and Elbow
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• 제5권2호
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• pp.102-109
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• 2002

Purpose: To evaluate the results of the treatment of the supracondylar fractures of the humerus according to the fixation methods in adults Materials and Methods: Seven patients, aged 55 to 52 years (average,69 years), were reviewed after a mean follow-up of 37 months (range, 11-65 months). According to AO classification all fractures were classified as type A2 (simple transverse supracondylar fracture). Six patients underwent closed reduction and one patient, open reduction after failure of closed reduction. Percutaneous fixation with cannulated screws was performed to the 4 patients, per- cuta)leous fixation with Kirschner wires in 3 patients. All except one patients have associated medical problems. The results were assessed based on the Mayo Elbow Performance Score. Results: All the patients with cannulated screw fixation had stable bony union with excellent ranges of motion (mean: 5-125 degrees). All the three patients who received percuatnaous smooth K-wire fixation had nonunion with poor results, one of them had changed into cannulated screw. and then had good result. Conclusion: Although simple supracondylar fracture is similar to the pediatric fracture in nature, it should be firmly fixed with the method such as threaded cannualted screw rather than the simple fixation with K-wires.

• 한국안전학회지
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• 제11권1호
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• pp.11-15
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• 1996

For the assessment of fracture behaviors of structural components, various fracture mechanics parameters have been applied to date. New approaches to analyze structural fracture performance under elastic-plastic condition have been proposed by the development of testing methods for characterization of material behavior which is defying to the analysis by conventional fracture parameters. In this study, on the assumption that, initiation of crack propagation of a piping materials occurs when the crack tip strain field reaches "the local fracture strain", following two major issues are discussed ; 1) The relationship between the critical value of J-integral($J_{IC}$) and the local fracture strain (${\varepsilon}_c$) in uniaxial tensile test in the region of maximum reduction area was described. 2) To proved the validity of above relations a series of tests were performed under various temperature and on the different piping materials.materials.

• 한국구조물진단유지관리공학회 논문집
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• 제26권6호
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• pp.182-192
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• 2022

취성파괴는 구조물의 파괴거동 중 하나로서 구조재료의 내진성능에 큰 영향을 미친다. 하중속도는 취성파괴의 주요 발생원인 중 하나로 작용하며, 특히 지진과 같은 상황에서 건축물에 높은 하중속도가 작용하게 된다. 하지만 현재 국내·외 강구조 보-기둥 접합부의 내진성능평가는 대부분 정적실험을 통해 수행되고 있다. 따라서 기존 내진성능평가에서는 지진 시의 높은 하중속도에 의한 재료 인성 저하 및 최대변형률 감소 등의 요소에 따른 취성파괴가 충분히 고려되지 않았을 가능성이 존재한다. 본 연구에서는 기존 실험방법에 따른 낮은 하중속도에서의 정적실험과 진동대를 이용한 높은 하중속도에서의 동적실험을 각각 실시한다. 각 실험결과에 따른 파괴형상 및 구조성능 등을 비교·분석하고 최종적으로 하중속도의 크기가 접합부의 내진성능에 미치는 영향을 분석한다.

• 한국생산제조학회지
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• 제8권1호
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• pp.35-44
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• 1999

In a view point of earth environmental protection and social requirement, adhesively bonded structures of aluminum alloys have become to be employed for the purpose of decreasing fuel ratio by weight reduction and to improve performance in various engineering fields such as aircrafts, automobiles, rolling stocks and so on. In spite of such wide applications in adhesively bonded structures of aluminum alloys, the quantitative fracture criterion and evolution method of its bonded strength have not been established yet. The objective of this paper is to establish fracture criterion considering stress singularity at interface edges in adhesively bonded structures of aluminum alloys. Through the analyses of boundary element method and static fracture experiments with three different types of specimens in the adhesively bonded joints of aluminum alloys, its fracture criterion was proposed and discussed about strength evolution of adhesively bonded structures.

• 대한족부족관절학회지
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• 제18권4호
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• pp.217-221
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• 2014

Fracture and fracture-dislocation of the ankle may be caused by a variety of mechanisms. In addition to the fracture, injury of soft tissue such as ligaments, tendons, nerves, and muscles may occur. Among these, tibialis posterior tendon injury is difficult to identify due to swelling and pain at the fracture site. There is no clear finding in radiological examination, therefore, it is found during surgery. In this case, irreducible fracture-dislocation of the ankle due to tibialis posterior tendon interposition was observed after the primary operation. The authors obtained satisfactory results in performance of a secondary operation assisted with arthroscopy.

• Steel and Composite Structures
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• 제31권2호
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• pp.113-123
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• 2019

In this study, carbon fiber/epoxy (CF/EP) composites were interleaved with aramid nonwoven veils with an areal weight density of $8.5g/m^2$ to improve their Mode-I fracture toughness. The control and aramid interleaved CF/EP composite laminates were manufactured by VARTM in a [0]4 configuration. Tensile, three-point bending, compression, interlaminar shear, Charpy impact and Mode-I (DCB) fracture toughness values were determined to evaluate the effects of aramid nonwoven fabrics on the mechanical performance of the CF/EP composites. Thermomechanical behavior of the specimens was investigated by Dynamic Mechanical Analysis (DMA). The results showed that the propagation Mode-I fracture toughness values of CF/EP composites can be significantly improved (by about 72%) using aramid nonwoven fabrics. It was found that the main extrinsic toughening mechanism is aramid microfiber bridging acting behind the crack-tip. The incorporation of these nonwovens also increased interlaminar shear and Charpy impact strength by 10 and 16.5%, respectively. Moreover, it was revealed that the damping ability of the composites increased with the incorporation of aramid nonwoven fabrics in the interlaminar region of composites. On the other hand, they caused a reduction in in-plane mechanical properties due to the reduced carbon fiber volume fraction, increased thickness and void formation in the composites.

• Journal of Mechanical Science and Technology
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• 제16권5호
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• pp.599-608
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• 2002

Finite element analysis for the stress intensity factor (SIF) at the skin/stiffener structure with inclined central crack repaired by composite stiffened panels is developed. A numerical investigation was conducted to characterize the fracture behavior and crack growth behavior at the inclined crack. In order to investigate the crack growth direction, maximum tangential stress (MTS) criterion are used. Also, this paper is to study the performance of the effective bonded composite patch repair of a plate containing an inclined central through-crack. The main objective of this research is the validation of the inclined crack patching design. In this paper, the reduction of stress intensity factors at the crack-tip and prediction of crack growth direction are determined to evaluate the effects of various non-dimensional design parameter including; composite patch thickness and stiffener distance. We report the results of finite element analysis on the stiffener locations and crack slant angles and discuss them in this paper. The research on cracked structure subjected to mixed mode loading is accomplished and concludes that more work using a different approaches is necessary. The authors hope the present study will aid those who are responsible for the repair of damaged aircraft structures and also provide general repair guidelines.

• 대한기계학회논문집A
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• 제22권2호
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• pp.416-427
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• 1998

Unidirectional commingled-yarn-based carbon fiber(CF)/polyamide(PA) 6 composite was fabricated under molding pressures of 0.4, 0.6 and 1.0 MPa to study its flexural deformation and fracture behavior. Fiber/matrix interfacial bonding area became larger with an increase of molding pressure from 0.4 to 0.6 MPa. For molding pressures .geq. 0.6 MPa, good flexural performance of similar magnitudes was attained. For the fracture test, four kinds of notch direction were adopted : edgewise notches parallel (L) and transverse (T) to the major direction of fiber bundles, and flatwise notches parallel(ZL) and perpendicular(ZT) to this direction. Nominal bend strength for L and ZL specimens exhibited high sensitivity to notching. ZL specimens revealed the lowest values of the critical stress intensity factor $K_c$ which was slightly superior to those of unfilled PA6 matrix. Enlargement of the compression area for T specimens was analyzed by means of the rigidity reduction resulting from the fracture occurrence.