• Journal of Welding and Joining
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• 제11권1호
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• pp.42-51
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• 1993

In this study, investigations were conducted in calculating parameters of elastic-plastic fracture mechanics using single specimen. The validity of these testing methods was judged by the confirmation of multiple specimen method of stop block test. The results were as follows: In order to measure a fracture toughness using the instrumented impact test, two general requirement must be considered; One, setting up proper impact velocity considered the effect of loading and the other, the necessity of low blow test for obtaining true energy by the compliance correction. It was possible to detect a crack initiation point by calculating the compliance changing rate from a load-defection curve. Criterion of a stable crack growth, $T_{mat}$ could be estimated by using key-curve method for a base metal. and combining Kaiser's rebound compliance with Paris-Hutchison's $T_{appl}$ equation for the brittled zone of welding heat affected.at affected.d.

• 대한족부족관절학회지
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• 제26권2호
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• pp.59-65
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• 2022

The posterior malleolar fracture is relatively common fracture of the foot and ankle, but several aspects of this are still controversial. If the posterior malleolus is involved in the ankle fracture, the prognosis is usually poor. A computed tomography scan is essential for accurate diagnosis and treatment planning. Although indirect reduction and the anterior to posterior screw fixation technique have the advantages of a small incision with the requirement of relatively simple skills, direct open reduction and fixation from the posterior side provide a more biomechanically stable and accurate reduction. The precise reduction of the posterior malleolar fragment helps to achieve congruency of the tibia and fibula in the incisura and contributes to syndesmotic stability. It is important to determine the indications for surgical treatment by comprehensively evaluating the three-dimensional structure of the posterior malleolar fracture and all related injuries to the ankle.

• 대한기계학회논문집
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• 제13권3호
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• pp.472-478
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• 1989

본 연구에서는 FRP의 파괴인성평가를 위한 기초적인 자료를 얻기 위하여 FRP 중에서도 널리 사용되고 있는 SMC재를 준비하고 3점 굽힘시험을 실시하여 노치선단에서의 손상거동 및 균열진전저항유선으로부터 안정파괴개시점을 검토하였다.

• Journal of Trauma and Injury
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• 제20권1호
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• pp.26-32
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• 2007

Purpose: Hemorrhagic shock is the leading cause of death in patients with pelvic bone fractures. The majority of blood loss is due to injured pelvic arteries and retroperitoneal veins and to bleeding from the fracture site itself. Pelvic angiography and embolization of injured vessels is an effective way to control continuous bleeding. However, identifying the bleeding focus in hemodynamically unstable patients before diagnostic intervention is difficult. The purpose of this study was to determine the correlation between fracture patterns in hemodynamically unstable patients with pelvic fractures and later pelvic angiography findings. Methods: We performed a retrospective study of 21 hemodynamically unstable patients with pelvic fractures admitted to our emergency department between April 2001 to April 2006. All 21 patients underwent pelvic angiography. Pelvic fractures were assessed according to the Tile's classification and the degree of injury was assessed using the Injury Severity Score (ISS) and Revised Trauma Score (RTS). The hemodynamic status of the patients was defined using vital signs, base excess, and blood lactate. Fracture patterns were compared with hemodynamic status and angiography findings. Results: In the 5year study period, 21 hemodynamically unstable pelvic bone fracture patients were admitted; ten were men (47.6%), and 11 were women (52.4%). The mean age was 41.1 years (range: ${\pm}20.1$). Of the 21 embolization was performed in 6 patient (28.6%): 1 patient of the 5 unstable pelvic bone fracture patients (20%), and 5 patients of 16 the stable pelvic bone fracture patients (31.3%). There were no significant differences between the RTS (p=0.587) and embolization rate (p=0.774) for either the stable patients or the unstable patients. Patients with arterial injury on angiography had a lower RTS compared with patients without arterial injury but there was no significant difference in ISS between the two groups. The angiographic injured sites were five internal femoral arteries and one external femoral artery. Conclusion: The findings in this study suggest that the pelvic fracture pattern in hemodynamically unstable patients with pelvic fractures does not correlate with pelvic angiography findings.

• 대한기계학회논문집A
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• 제31권4호
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• pp.432-440
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• 2007

In this study, we have investigated the closure behavior of fatigue cracks in SAPH440 steel plates under a mixed-mode I+II loading. A crack image capturing system as a direct measuring method was used to measure the closure levels at a crack tip. The crack closure levels in the fluctuation and stable sections were increased with the increase of the mode mixture ratio. The mode mixture ratio independent fatigue crack propagation rates equation was calculated by considering mixed-mode crack closure levels. The equation was examined according to the application method of crack opening ratio. The fracture surface analysis by C-scan method was also performed in order to investigate the closure mechanism and propagation mode of crack under the mixed-mode I+II loading. The crack closure under the mixed mode I+II is confirmed as a surface roughness closure by the quantitative analysis of fracture surface using the proposed surface roughness parameter.

• 콘크리트학회논문집
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• 제13권2호
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• pp.161-167
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• 2001

RILEM위원회가 제시한 3점 휨 시험은 하중-변위곡선 형상이 불규칙하고 안정된 균열 발생 후 최종 균열이 발생하기 때문에 정확한 파괴인성을 구하는 것은 어렵다. 그러나 디스크 시험은 균열개시하중만 알면 쉽게 파괴인성을 구할 수 있다. 따라서, RILEM위원회가 제시한 3점 휨 시험보다 파괴인성 계산의 편리함을 보이기 위해 중앙에 노치가 있는 고강도 콘크리트 디스크를 실험하여 실험결과와 유한요소해석에 의한 결과를 비교하였다. 또한 실험에 의한 파괴 포락선과 이론에 의한 파괴 포락선도 비교하였으며, 콘크리트 강도수준에 따른 파괴특성의 차이를 나타내었다. 본 연구의 결과는 다음과 같다 유한요소해석과 실험결과를 비교해 볼 때, 최대 원주방향 인장응력 이론을 적용한 유한요소해석은 실험결과와 좋은 일치를 보였다. 그리고 콘크리트의 강도수준에 따른 파괴특성의 차이는 균열개시하중과 파괴인성 등에 영향을 끼치지만 최종 균열전파각의 변화에는 큰 영향이 없었다. 또한, 최대 원주방향 인장응력이론에 의한 파괴 포락선과 실험에 의한 포락선이 일치하지 않는 이유는 콘크리트에서 혼합모드와 면내전단모드(모드 II) 파괴를 유발하는 데 필요한 에너지량이 크기 때문이라고 판단된다

• 방사선산업학회지
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• 제9권2호
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• pp.91-102
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• 2015

The iridium disc, generally used in industrial radiography, is examined to find the fracture morphology and fine particles remaining on the shear blank surface. Randomly selected 1,200 discs were observed under a scanning electron microscope tilted more than $45^{\circ}$. Fracture surfaces are classified into three groups: (1) surface fall-out, (2) fracture on the edge and (3) multi-step brittle fracture, which shows the mutual relationship between the fracture morphology and remaining particles. Fracture particles were removed by cleaning the discs in a ultrasonic bath with acetone and collected at the bottom. Removed number of the particles were counted for each different group of fracture surfaces. Followings are conclusions: (1) About 80.5% of discs (966/1,200), have sound plastic shear surfaces with particles remained. (2) About 2% discs accompany surface fall-out's having large particles tens of ${\mu}m$, which is stable not to be pulled out even after the considerably long time of ultrasonic cleaning. (3) About 5% discs contain the fractures on the edge and the particles are removed thoroughly within 30 minutes. (4) 234 discs out of 1,200 discs have multi-step fracture surfaces whose particles never removed in a short period of time but come out very slowly. Such a disc having multiple-step fracture is attributed to the promate cause to the 'leaker'. It is noted here that the discs having mutiple-step fractures should be treated separately with special care, and it is need to study how to treat them.

• Clinics in Shoulder and Elbow
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• 제21권4호
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• pp.234-239
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• 2018

Background: In elbow fracture-dislocation, partial excision of the comminuted radial head fracture that is not amenable to fixation remains controversial considering the accompanying symptoms. This study was undertaken to evaluate the results of radial head partial excision when the comminuted radial head fracture involved <50% of the articular surface in all-arthroscopic repair of elbow fracture-dislocation. Methods: Patients were divided into two groups based on the condition of the radial head fracture. In Group A, the patients had a radial head comminuted fracture involving <50% of the articular surface, and underwent arthroscopic partial excision. Group B was the non-excision group comprising patients with stable and non-displacement fractures. Follow-up consultations were conducted at 6 weeks and at 3, 6, 12, and 24 months after surgery. Results: In all, 19 patients (Group A: 11; Group B: 8) met the inclusion criteria and were enrolled in the study. At the final follow-up, all 19 patients showed complete resolution of elbow instability. No significant differences were observed in the range of motion, visual analogue scale score, and Mayo elbow performance score between groups. Radiological findings did not show any complications of the radiocapitellar joint. However, nonunion of the coracoid fracture was observed in 3 patients (Group A: 1; Group B: 2), without any accompanying instability and clinical symptoms. Conclusions: Considering that the final outcome is coronoid fracture fixation and lateral collateral ligament complex repair for restoring elbow stability, arthroscopic partial excision for radial head comminuted fractures involving <50% of articular surface is an effective and acceptable treatment for elbow fracture-dislocation.

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2000년도 암반공학문제의 수치해석(Numerical Analysis in Rock Engineering Problems)
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• pp.67-75
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• 2000

암석의 파괴인성 측정법으로서 최근에 연구되고 있는 Brazilian 파괴인성 시험을 PFC code를 이용하여 수치해석적으로 시뮬레이션하였다. 이로부터 가압면 형태, 시험편과 모델링 입자의 크기 관계, 가압면 각도 범위, 하중속도 등의 영향 변수에 대한 분석 및 적정 기준에 대해 검 토하였다. 균등한 하중 전달을 위해 가압면이 평면인 Brazilian 시험편을 도입하였는데, 시험편 중앙에서 초기 인장균열을 생성하고 파괴인성 산정에 필요한 안정한 인장균열 진전 시점의 임계하중이 나타나는 하중-변위 곡선을 얻을 수 있는 가압면 각도는 $20^{\circ}C$ -$40^{\circ}C$ 범위로 나타났다. 가압면 각도가 $20^{\circ}C$ 인 경우에, 디스크 시험편의 구성입자 반경이 1 mm 이하이고 하중속도가 0.01 mm/s 이하인 조건에서는 거의 일정한 파괴인성값을 얻을 수가 있었다. 가압면 각도가 $20^{\circ}C$이상이고 하중속도가 0.01 mm/s 이하는 파괴인성 측정에서 중요한 기본 조건인 시험편 중 에서의 인장균열 생성 및 이 인장균열의 안정적인 진전 제어를 위한 조건인 것으로 볼 수가 있다.

• 터널과지하공간
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• 제10권3호
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• pp.320-328
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• 2000

암석의 파괴인성 측정법으로서 최근에 연구되고 있는 Brazilian 파괴인성 시험을 PFC code를 이용하여 수치 해석적으로 시뮬레이션하였다. 이로부터 가압면 형태, 시험편과 모델링 입자의 크기 관계, 가압면 각도 범위, 하중속도 등의 영향 변수에 대한 분석 및 적정 기준에 대해 검토하였다. 균등한 하중 전달을 위해 가압면이 평면인 Brazilian 시험편을 도입하였는데, 시험편 중앙에서 초기 인장균열을 생성하고 파괴인성 산정에 필요한 안정한 인장균열 진전 시점의 임계하중이 나타나는 하중-변위 곡선을 얻을 수 있는 가압면 각도는 20$^{\circ}$~40$^{\circ}$범위로 나타났다. 가압면 각도가 20$^{\circ}$인 경우에, 디스크 시험편의 구성입자 반경이 1mm 이하이고 하중속도가 0.01mm/s 이하인 조건에서는 거의 일정한 파괴인성값을 얻을 수가 있었다. 가압면 각도가 20$^{\circ}$이상이고 하중속도가 0.01mm/s 이하는 파괴인성 측정에서 중요한 기본 조건인 시험편 중앙에서의 인장균열 생성 및 이 인장균열의 안정적인 진전 제어를 위한 조건인 것으로 볼 수가 있다.