• 비파괴검사학회지
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• 제18권4호
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• pp.278-291
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• 1998

연속섬유강화 복합재료의 경우 보강섬유의 파괴, 모재의 파괴, 섬유와 모재의 분리, 층간파괴 등의 복합적인 파괴현상이 동반되고 특히 균열성장과 균열성장 정지가 균열가교 현상 때문에 반복되므로 안정성장과 불안정성장이 불규칙하게 반복된다. 따라서 주균열 성장의 개시점과 불안정 파괴점에서의 파괴인성치를 정확하게 결정한다는 것은 매우 어려운 것이다. 본 연구에서는 CFRP에 대하여 파괴인성 실험과 병행하여 실시간으로 결함을 검출하는 새로운 방법인 AE분석법 및 비디오 마이크로 스코프를 이용하여 파괴과정을 기록하여 검토, 분석함으로서 손상의 정도와 파괴기구를 규명하였을 뿐만 아니라 주균열 성장의 개시점, 균열가교 역할을 하는 섬유다발의 파단점, 균열의 불안정 파괴 개시점을 찾아 이를 기초로 균열진전 저항곡선에 의한 파괴인성치를 평가하여 신뢰성 있는 파괴인성 측정법을 제시하였다.

• Journal of Trauma and Injury
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• 제27권2호
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• pp.29-32
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• 2014

Pelvic bone fracture with hemodynamic instability is fatal and the mortality rate can range up to 40%. Despite the big advances in the treatment of massive bleeding and hemorrhagic shock, the mortality associated with hemodynamically unstable pelvic bone fractures remains high. The gold standard of treatment for pelvic bone fracture with hemodynamic instability has not yet been determined and is an issue of main discussion among many doctors. Retroperitoneal packing is not yet wide spread in Korea, but is a good modality for managing of massive bleeding from pelvic bone fractures when an angiography suite or an expert surgeon is not available. A vacuum-assisted closure (VAC) system can also be applied with retroperitoneal packing in the manner of damage control surgery and open abdomen surgery. We present the case of a 51-year-old male who had a pelvic bone fracture with massive bleeding. We performed retroperitoneal gauze packing with a VAC system for the first time. The postoperative vital signs of patient were immediately stable, the massive bleeding was easily and quickly controlled, and the amount of transfusion of blood components was reduced.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.230-235
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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 fer 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.

• 대한기계학회논문집A
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• 제21권12호
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• pp.2090-2095
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• 1997

The plane stress fracture toughness for thin aluminum alloy(2024-T3 and 7075-T6) specimens are characterized by using compact-tension (CT) specimens. Anti-buckling plates were fabricated on both sides of the thin CT specimens to prevent the buckling phenomena which caused by the 45.deg. C plastic yielding at the crack tip under the plane stress condition. The plane stress fracture toughnesses determined by three different procedures are compared with each others. The plane stress fracture toughnesses are also compared with a few published values which were determined by using center-cracked panel specimens.

• Clinics in Shoulder and Elbow
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• 제20권1호
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• pp.49-56
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• 2017

Since the olecranon fractures are caused by relatively low-energy injuries, such as a fall from standing height, they are usually found without comminution. Less commonly they can be developed by high-energy injuries and have severe concomitant comminution or injuries to surrounding structures of the elbow. Because the fracture by nature is intra-articular with the exception of some avulsion-type fracture, a majority of olecranon fractures are usually indicated for surgical treatment. Even if there is minimal displacement, surgical treatment is recommended because there is a possibility of further displacement by the traction force of triceps tendon. The most common type of olecranon fracture is displaced, simple non-comminuted fracture (that is, Mayo type IIA fractures). Although tension band wiring was the most widespread treatment method for these fractures previously, there is some trends toward fixation using locking plates. Primary goal of the surgery is to restore a congruent joint and extensor mechanisms by accurate reduction and stable fixation so that range of motion exercises can be performed. The literature has shown that good clinical outcomes are achieved irrespective of surgical fixation technique. However, since the soft tissue envelope around the elbow is poor and the implants are located at the subcutaneous layer, implant irritation is still the most common complication associated with surgical treatment.

• Journal of Welding and Joining
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• 제7권1호
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• pp.42-50
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• 1989

The application of fracture mechanics is being increased gradually to assess the safety of welded structures containing crack. Fatigue crack propagation behavior and elastic-plastic fracture toughness J$_{IC}$ of home made flux cored wire(1.22mm) CO$_{2}$ weldments was discussed. Especially fatigue crack propagation test was carried out by .DELTA.K control instead of load control and elastic-plastic fracture toughness J$_{IC}$ was obtained by ASTM-R curve method on C.T.specimen in transverse direction of weldments. The results obtained are as follows; (1) Weld metal presented an almost complete similarity to base metal on fatigue crack propagation rate in transverse direction. (2) Weld metal was more than base metal on J$_{IC}$ value in transverse direction. (3) F.C.W. CO$_{2}$ weldments had an excellent characteristic of fatigue crack propagation rate and J$_{IC}$ in less than 50kg/mm$^{2}$ steel grade, this would result from that weld metal had good static strength.trength.

• Computers and Concrete
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• 제18권2호
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• pp.267-278
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• 2016

In order to observe the internal damage of concrete in real time, we introduced acoustic emission nondestructive detecting technology into a series of fracture tests; the test results revealed the whole process that concrete undergoes when it sustains damage that leads to failure, according to the change rules of the acoustic emission parameters. The results showed that both the initiation and unstable loads can be accurately determined using the abrupt change of the acoustic emission rate curves and the turning point of the acoustic emission parameters' accumulative curves. The whole process, from damage to failure, includes five phases, beginning with damage, such as cracking, a stable crack growth process, a critical unstable stage, and unstable propagation. The brittle fracture characteristics of concrete change when steel bars are joined, because the steel bars and the concrete structure bond, which causes an increase in the acoustic emission signals within the fracture process of the reinforced concrete. The unstable propagation stage is also extended. Our research results provide a valid methodology and technical explanations, which can help researchers to monitor the cracking process of concrete structures, in real time, during actual projects.

• 대한금속재료학회지
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• 제47권12호
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• pp.787-796
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• 2009

The fracture toughness improvement of Ni-Mn-Ga-Fe ferromagnetic shape memory alloys containing ductile particles was explained by direct observation of microfracture processes using an in situ loading stage installed inside a scanning electron microscope (SEM) chamber. The Ni-Mn-Ga-Fe alloys contained a considerable amount of ductile particles in the grains after the homogenization treatment at $800{\sim}1100^{\circ}C$. ${\gamma}$ particles were coarsened and distributed homogeneously along {$\beta}$ grain boundaries as well as inside {$\beta}$ grains as the homogenization temperature increased. The in situ microfracture observation results indicated that ${\gamma}$ particles effectively acted as blocking sites of crack propagation, and provided stable crack growth that could be confirmed by the R-curve analysis. This increase in fracture resistance with increasing crack length improved overall fracture properties of the alloys containing ${\gamma}$ particles.

• 대한정형외과학회지
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• 제55권2호
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• pp.178-182
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• 2020

하부 천골의 단독 골절은 일반적으로 저에너지 손상으로 안정된 골절이 많아 대부분의 경우에서 보존적 치료가 이루이지고 있고 그 결과도 좋은 것으로 보고되고 있다. 하지만 전위된 불안정 골절에서는 수술적 치료의 필요성이 요구되나 치료 방법이 정립되어 있지 않으며 증례보고마저 매우 드물다. 이에 저자들은 하부 천골의 전위된 횡골절에 대해 관혈적 정복 및 이중 금속판을 이용한 내고정술을 치험한 증례를 보고하고자 한다.

• 대한한방체열의학회지
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• 제1권1호
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• pp.28-37
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• 2002

Stable Compression Fractures(SCF hereafter) are most often caused by trauma such as traffic accidents. These SCFs usually occur in the thoracic and lumbar regions of the spinal cord. Human life spans have increased as a result of medical advances, which in turn has led to an increase in the elderly population. SCFs are divided into the categories of stable and unstable. The categories are determined through X-rays and P/Ex tests. The D.I.T.I. is then used to diagnose the severity and prognosis of the fracture injuries, and it allows an objective evaluation of the symptoms. This author researched 40 patients who were treated at Wonkwang University Oriental Medical Center from October 1995 to December 1996. The patients were diagnosed by X-ray as having SCFs and treated primarily with acupuncture. Both the changes in D.I.T.I. and patients' self-diagnoses of their conditions before and after treatment yielded the meaningful results which have been presented here. 1. 75% of those who suffer from Stable Compression Fractures are 60 years of older. Of those, the ratio of male to female is 1 to 4. This is due in part to the fact that many elderly women seek Oriental medicine treatment for conditions associated with advanced age. 2. 53.3% of these injuries occurred between T11 and L2. 3. 65% of patients were hospitalized for 10 to 29 days, and then able to be treated on an outpatiens basis. 4. The D.I.T.I. results showed 50% below $0.2^{\circ}C$, 30% between 0.3 and $0.5^{\circ}C$, 10% between 0.5 and $0.7^{\circ}C$, 10% between 0.7 and $0.9^{\circ}C$, and 0% over $0.9^{\circ}C$. 5. The results of treatment using Modified Evaluation System in Thoracolumbar Vertebral Fractures Method showed that 55% of patients achieved excellent recovery and 40% achived good recovery. After comparing the D.I.T.I. results before and after treatment, we found 50% of patients showed excellent recovery $({\Delta}T{\leq}0.2)$ and 40% showed good recovery$(0.2<{\Delta}T{\leq}0.5)$.