• Journal of Trauma and Injury
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• 제19권1호
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• pp.47-53
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• 2006

Purpose: Recently, the American Heart Association recommended that routine cervical spine protection in submerged patients was not necessary, except in high-energy injury situations. However, until now, this recommendation has few supportive studies and literatures. This retrospective study was performed to demonstrate the risk of cervical spine injury in patients who had been submerged in a river. Methods: Seventy-nine submerged patients who visited St. Mary's Hospital between January 2000 and December 2005 were included in this retrospective study. We investigated and analyzed the victim's age, sex, activity on submersion, mental status and level of severity at admission, prognosis at discharge, associated injuries, and risk group by using the medical records and cervical spine lateral images. According to the activity on submersion, victims were classified into three groups: high risk, low risk, and unknown risk. The reports of radiologic studies were classified into unstable fracture, stable fracture, sprain, degenerative change, and normal. Results: The patients' mean age was 36.8 yrs, and 54% were males. Of the 79 patients, adult and adolescent populations (80%) were dominant. Jumping from a high bridge (48%) was the most common activity on submersion and accounted for 52% of the high-risk group. The Glasgow coma scale at admission and the cerebral performance scale at discharge showed bimodal patterns. The results of the radiologic studies showed one stable fracture, one suspicious stable fracture, and 18 sprains. The incidence of cervical spine fracture in submerged patients was 2.5% in our study. The incidence of cervical spine injury was higher in the high-risk group than it was in the low-risk group, especially in the jumping-from-high-bridge subgroup; however this observation was not statistically significant. No other factors had any significant effect on the incidence of cervical spine injury. Conclusion: Our study showed that even submerged patients in the high risk group had a low incidence of cervical spine fracture and that the prognosis of a patient did not seem to be influenced by the cervical spine fracture itself.

• Computers and Concrete
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• 제7권4호
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• pp.387-402
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• 2010

From typical stress-axial strain curve and stress-volume strain curve of a concrete under uniaxial compression, the initiation and localization of microcracks within the interior of the specimen can be identified. The occurrence of random microcrack indicates the end of the linear elasticity, and the localization of microcrack implies formation of major crack, which triggers the onset of unstable crack propagation. The interval between initiation and localization of microcracks is characterized by a stable microcrack growth. Based on fracture behavior observed from a uniaxial compressive test of a concrete cylinder, a model has been developed to extract fundamental fracture properties of a concrete, i.e. the equivalent fracture toughness and the size of fracture process zone. The introduction of cracking Poisson's ratio accounts for tensile failure characteristics of concrete even under uniaxal compression. To justify the validity of the model proposed, tests on three-point bending have been performed to obtain the fracture toughness in accordance with two parameter fracture model and double-K fracture model. Surprisingly, it yields favorably comparable results and provides an encouraging alternative approach to determine fracture properties for concretes.

• 대한토목학회논문집
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• 제7권1호
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• pp.75-82
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• 1987

본(本) 연구(硏究)는 소규모강복범위(小規模降伏範圍)를 벗어나는 대규모강복조건하(大規模降伏條件下)에서 구조안정성(構造安定性)에 관(關)한 중요(重要)한 문제(問題)인 불안정연성파괴(不安定延性破壞)를 평가(評價)할 수 있는 파괴역학인자(破壞力學因子)로서의 J 적분(積分)을 수치해(數値解)로서 구하는데 그 목적(目的)을 두었다. 이를 위해 균열재(龜裂材)의 균열선단요소(龜裂先端要素)로 8절점등방특이요소(節點等方特異要素)를 사용(使用)하고, 균열발생(發生)은 파괴인성(破壞靭性) $J_{IC}$를 초과할 때 일어나도록 하였으며, 그리고 균열성장(成長)의 취급(取級)은 균열개구각(龜裂開口角)을 이용(利用)했다. 본(本) 연구(硏究)에 의해 해석(解析)된 J 적분치(積分値)를 사용(使用)하여 균열재의 균열발생 과 안정성장(安定成長), 불안정(不安定) 발생점(發生點)을 찾은 결과(結果) 다른 연구결과(硏究結果)와 잘 일치(一致)하고 있어 탄소성(彈塑性)을 고려(考慮)한 J 적분치(積分値)가 균열의 안정성장(安定成長) 및 불안정연성파괴(不安定延性破壞) 문제(問題)를 다루는 파괴역학인자(破壞力學因子)로서 직접(直接) 이용(利用)될 수 있음을 보였다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제48권5호
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• pp.267-276
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• 2022

Objectives: Recently a modified high-submandibular approach (HSMA) has been introduced for treatment of condylar fracture. This approach involves an incision line close to the mandibular angle and transmasseteric transection, leading to a low incidence of facial palsy and allowing good visualization of the condyle area, especially the condylar neck and subcondyle positions. This study reports several cases managed with this modified HSMA technique for treating condylar fractures. Materials and Methods: Six cases of condylar fractures treated with modified HSMA technique were reviewed. Results: Three unilateral subcondylar fracture, 1 bilateral subcondylar fracture, 1 unilateral condylar neck fracture, 1 unlateral simultaneous condylar neck and subcondylar fracture cases were reviewed. All the cases were successfully treated without any major complication. Conclusion: Reduction, fixation, and osteosynthesis of condylar fractures via the modified HSMA technique enabled effective and stable treatment outcomes. Therefore, the described approach can be used especially for subcondylar and condylar neck fractures with minimal complications.

• Journal of Korean Neurosurgical Society
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• 제64권6호
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• pp.944-949
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• 2021

Objective : The stability is an important factor to decide the treatment plan in thoracolumbar burst fracture patients. Patients with an unstable burst fracture generally need operative management. Decrease in vertebral body height, local kyphosis, involvement of posterior column, and/or canal compromise are considered important factors to determine the treatment plan. On the other hand, in thoracolumbar injury classification system (TLICS), surgery is recommended in patients with TLICS of more than 5 points. The purpose of this study was to apply the TLICS score in patients with thoracolumbar burst fractures and to distinguish the differences of treatment plan on burst fracture. Methods : All patients, diagnosed as a thoracolumbar burst fracture between January 2006 and February 2019 were included in this study. Unstable thoracolumbar burst fracture was defined as burst fracture with neurologic deficit, three-column injury, kyphosis over 30 degrees, decrease of anterior body height over 40 percent and canal comprise more than 50%. TLICS score was measured with morphology, neurological involvement and posterior ligamentous complex integrity. The existence of instability was compared with TLICS score. Results : Total 233 patients (131 men, 102 women) were included in this study. In Denis classification, 51 patients (21.9%) diagnosed as stable burst fracture while 182 patients (78.1%) had unstable burst fracture. According to TLICS, 72 patients (30.9%) scored less than 4, while 161 patients (69.1%) scored 4 or more. All the patients with stable burst fracture scored 2 in TLICS. Twenty-one patients (9.0) scored 2 in TLICS but diagnosed as unstable burst fracture. Thirteen patients had over 40% of vertebra body compression, four patients had more than 50% of canal compromise, three patients had both body compression over 40% and kyphosis over 30 degrees, one patients had both body compression and canal compromise. Fifteen patients presented kyphosis over 30 degrees, and three (20%) of them scored 2 in TLICS. Seventy-three patients presented vertebral body compression over 40% and 17 (23.3%) of them scored 2 in TLICS. Fifty-three patients presented spinal canal compromise more than 50%, and five (9.4%) of them scored 2 in TLICS. Conclusion : Although the instability of thoracolumbar burst fracture was regarded as a critical factor for operability, therapeutic strategies by TLICS do not exactly match with the concept of instability. According to the concept of TLICS, it should be reconsidered whether the unstable burst fracture truly unstable to do operation.

• 콘크리트학회논문집
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• 제14권5호
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• pp.689-697
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• 2002

콘크리트 삼점휨 시험편의 변위제어에 의한 동적 파괴실험으로 하중과 하중점-변위가 측정되었다. 변형률 게이지를 사용하여 균열의 성장길이가 측정되었으며, 균열이 성장되는 동안의 평균속도는 0.16 ~ 66 m/sec이었다. 균열성장에 대한 파괴에너지는 측정된 외부일에 대한 하중점-변위에 대한 운동에너지와 영구변형이 고려되지 않은 탄성에너지의 차이로부터 계산되었다. 모든 균열속도에 대해 23mm의 균열성장 동안 미소균열이 성장되며, 51 mm의 최대 탄성0에너지까지 안정 균열성장과 이후의 불안정 균열성장을 보였다. 균열속도가 66msec인 경우를 제외하고 80mm의 균열성장에서 균열성장의 구속이 관측되었다. 균열속도에 대한 파괴에너지와 파괴에너지율의 분석은 13mm/sec보다 느린 경우에 정적 거동을 그리고 1.9m/sec보다 빠른 속도에서 동적 거동을 보였다. 동적 실험에서 측정된 하중과 하중점-변위 관계의 큰 차이에도 불구하고 관성력과 균열성장길이 그리고 탄성에너지의 차이로 불안정 균열성장 이전의 균열속도에 대한 파괴저항은 균열속도에 영향을 받지 않았다. 안정 균열성장 동안의 최대 파괴저항은 최대하중 이후 최대 탄성에너지에서 발생되며, 동적 실험이 정적 실험보다 147% 큰 값이었다.

• Computers and Concrete
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• 제5권4호
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• pp.389-400
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• 2008

In this work we simulate explicitly the dynamic fracture propagation in reinforced concrete beams. In particular, adopting cohesive theories of fracture with the direct simulation of fracture and fragmentation, we represent the concrete matrix, the steel re-bars and the interface between the two materials explicitly. Therefore the crack nucleation within the concrete matrix, through and along the re-bars, the deterioration of the concrete-steel interface are modeled explicitly. The numerical simulations are validated against experiments of three-point-bend beams loaded dynamically under various strain rates. By extracting the crack-tip positions and the crack mouth opening displacement history, a two-stage crack propagation, marked by the attainment of the peak load, is observed. The first stage corresponds to the stable crack advance, the second one, the unstable collapse of the beam.

• 대한치과마취과학회지
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• 제14권4호
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• pp.233-236
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• 2014

In order to reduce jaw fracture accompanied by basal skull or nasal fracture, submental intubation could be generally performed. Albeit submental intubation has been widely accepted, it could develop complications such as nerve injury, glandular duct injury, and orocutaneous fistula. Here, we suggest oral intubation for overcoming complications and providing more stable surgical environment in emergency case. Under oral intubation maintaining in retromolar triangle and buccal corridor space, intermaxillary fixation was successfully underwent in 38-years-old female patient with Le Fort I fracture accompanied by pneumocephalus.

• Journal of Korean Dental Science
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• 제10권2호
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• pp.82-86
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• 2017

Oral and maxillofacial surgery (OMFS) trauma cases are commonly treated under general anesthesia. The purpose of this case report is to introduce an alternative method of anesthesia in patients who refuse general anesthesia. A combination of dexmedetomidine and ketamine for sedation anesthesia in 3 frequent fracture types in the field of OMFS-Le Fort I fracture, mandibular fracture, and alveolar bone fracture-was used. Dexmedetomidine as the single agent has not shown stable success rates for invasive procedures. To overcome some of the pitfalls with dexmedetomidine, combination sedation using ketamine was performed. Visual analogue scale scores were recorded postoperatively. Dexmedetomidine combined with ketamine administration provided safe and effective sedation and anxiolysis for surgical reduction and internal fixation of OMFS fractures. It showed advantages of decreased admission time, reduced expenses, minimal pain, and reduced anesthetic burden for the patient thus ultimately increasing overall satisfaction.

• Geomechanics and Engineering
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• 제16권1호
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• pp.35-47
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• 2018

This paper investigates the mechanisms of tunnel spalling and massive tunnel failures using fracture mechanics principles. The study starts with examining the fracture propagation due to tensile and shear failure mechanisms. It was found that, fundamentally, in rock masses with high compressive stresses, tensile fracture propagation is often a stable process which leads to a gradual failure. Shear fracture propagation tends to be an unstable process. Several real case observations of spalling failures and massive shear failures in boreholes, tunnels and underground roadways are shown in the paper. A number of numerical models were used to investigate the fracture mechanisms and extents in the roof/wall of a deep tunnel and in an underground coal mine roadway. The modelling was done using a unique fracture mechanics code FRACOD which simulates explicitly the fracture initiation and propagation process. The study has demonstrated that both tensile and shear fracturing may occur in the vicinity of an underground opening. Shallow spalling in the tunnel wall is believed to be caused by tensile fracturing from extensional strain although no tensile stress exists there. Massive large scale failure however is most likely to be caused by shear fracturing under high compressive stresses. The observation that tunnel spalling often starts when the hoop stress reaches $0.4^*UCS$ has been explained in this paper by using the extension strain criterion. At this uniaxial compressive stress level, the lateral extensional strain is equivalent to the critical strain under uniaxial tension. Scale effect on UCS commonly believed by many is unlikely the dominant factor in this phenomenon.