• Journal of Advanced Marine Engineering and Technology
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• 제23권4호
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• pp.488-503
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• 1999

The present paper considers the constraint effect on J-R curves under the two-parameter $J-A_2$ controlled crack growth within a certain amount of crack extension. Since the parameter $A_2$ in $J-A_2$ three-term solution is independent of applied loading under fully plasticity or large-scale defor-mation $A_2$ is a proper constraint parameter uring crack extension. Both J and $A_2$ are used to char-acterize the resistance curves of ductile crack growth using J as the loading level and $A_2$ are used to char-acterize the resistance curves of ductile crack growth using J as the loading level and A2 as a con-straint parameter. Approach of the constraint-corrected J-R curve is proposed and a procedure of transferring the J-R curves determined from standard ASTM procedure to non-standard speci-mens or real cracked structures is outlined. The test data(e.g. initiation toughness JIC and tearing modulus $T_R$) of Joyce and Link(Engineer-ing Fracture Mechanics 1997, 57(4) : 431-446) for single-edge notched bend[SENB] specimen with from shallow to deep cracks is employed to demonstrate the efficiency of the present approach. The variation of $J_{IC}$ and $T_R$ with the constraint parameter $A_2$ is obtained and a con-straint-corrected J-R curves is constructed for the test material of HY80 steel. Comparisons show that the predicted J-R curves can very well match with the experimental data for both deep and shallow cracked specimens over a reasonably large amount of crack extension. Finally the present constraint-corrected J-R curve is used to predict the crack growth resistance curves for different fracture specimens. over a reasonably large amount of crack extension. Finally the present constraint-corrected J-R curve is used to predict the crack growth resistance curves for different fracture specimens. The constraint effects of specimen types and specimen sizes on the J-R curves can be easily obtained from the constrain-corrected J-R curves.

• 한국지반환경공학회 논문집
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• 제8권4호
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• pp.27-39
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• 2007

본 논문은 유효수직응력과 간극분포의 공간적 상관길이에 따른 거친 단일 균열 내에서의 유체흐름에 대한 특성을 수치적으로 분석한 것이다. 균열 내의 공간적으로 상관된 변화하는 간극분포는 지구통계학적 방법(i.e. Turning Bands algorithm)을 이용하여 발생시켰으며, 유효수직응력에 따른 간극분포의 변화를 묘사하기 위해 유효수직응력과 역학적 간극 사이의 단순한 비선형 관계식를 이용하였으며, 이를 흐름 모형에 결합하였다. 모의분석결과 균열 내의 유체흐름은 적용된 유효수직응력과 간극분포의 공간적 상관길이에 따라 변화하는 간극분포의 기하학적 특성에 크게 영향을 받은 것으로 나타났다. 그밖에 본 연구에서 모의된 유체흐름의 결과를 이용하여 유효수직응력과 균열의 유효투수성 사이의 관계를 나타내는 수정 Louis 식을 제안하였다.

• 대한두개안면성형외과학회지
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• 제18권4호
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• pp.249-254
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• 2017

Background: Lower eyelid incisions are widely used for the orbital approach in periorbital trauma and aesthetic surgery. In general, the subciliary approach is known to cause disposition of the lower eyelid by scarring the anterior lamella in some cases. On the other hand, many surgeons believe that a transconjunctival approach usually does not result in such complications and is a reliable method. We measured positional changes in the lower eyelid in blowout fracture repair since entropion is one of the most serious complications of the transconjunctival orbital approach. Methods: To measure the positional changes in the lower eyelids, we analyzed preoperative and postoperative photographs over various time intervals. In the analysis of the photographs, marginal reflex distance 2 ($MRD_2$) and eyelash angle were used as an index of eyelid position. Statistical analyses were performed to identify the significance in the positional changes. All patients underwent orbital reconstruction through a transconjunctival incision by a single plastic surgeon. Results: In 42 blowout fracture patients, there was no statistical significant difference in the MRD2 and eyelash angle. Furthermore, there were no clinical complications, such as infection, hematoma, bleeding, or implant protrusion, during the follow-up periods. Conclusion: The advantages of the transconjunctival approach for orbital access include minimal scarring and a lower risk of eyelid displacement compared with other approaches. Based on these results, we recommend the transconjunctival approach for orbital exposure as a safe and reliable method.

• Restorative Dentistry and Endodontics
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• 제45권2호
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• pp.22.1-22.10
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• 2020

Objectives: This study investigated the influence of glide path size and operating kinetics on the time to reach the working length and the fracture resistance of Twisted File (TF) and Endostar E3 files. Materials and Methods: A total of 120 mandibular single-rooted premolars were selected. Two methods of kinetic motion (TF adaptive and continuous rotary motion) and file systems (TF and Endostar E3) were employed. The files were used in root canals prepared to apical glide path sizes of 15, 20, and 25. The time taken to reach the working length and the number of canals used before the instrument deformed or fractured were noted. Fractured instruments were examined with scanning electron microscopy. Results: The TF system took significantly more time to reach the working length than the Endostar E3 system. Both systems required significantly more time to reach the working length at the size 15 glide path than at sizes 20 and 25. A greater number of TFs than Endostar E3 files exhibited deformation, and a higher incidence of instrument deformation was observed in adaptive than in continuous rotary motion; more deformation was also observed with the size 15 glide path. One TF was fractured while undergoing adaptive motion. Conclusions: No significant difference was observed between continuous rotary and adaptive motion. The TF system and adaptive motion were associated with a higher incidence of deformation and fracture. Apical glide path sizes of 20 and 25 required significantly less time to reach the working length than size 15.

• Journal of Korean Neurosurgical Society
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• 제56권3호
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• pp.211-217
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• 2014

Objective : In Korea, early vertebroplasty (EVP) or delayed vertebroplasty (DVP, which is performed at least 2 weeks after diagnosis) were performed for the treatment of acute osteoporotic compression fracture (OCF) of the spine. The present study compared the outcomes of two surgical strategies for the treatment of single-level acute OCF in the thoracolumbar junction (T12-L2). Methods : From 2004 to 2010, 23 patients were allocated to the EVP group (EVPG) and 27 patients to the DVP group (DVPG). Overall mean age was $68.3{\pm}7.9$ and minimum follow-up period was 1.0 year. Retrospective study of clinical and radiological results was conducted. Results : No significant differences in baseline characteristics were observed between the two groups. As expected, mean duration from onset to vertebroplasty and mean duration of hospital stay were significantly longer in the DVPG ($17.1{\pm}2.1$ and $17.5{\pm}4.2$) than in the EVPG ($3.8{\pm}3.3$ and $10.8{\pm}5.1$, p=0.001). Final clinical outcome including visual analogue scale (VAS), Oswestry Disability Index, and Odom's criteria did not differ between the two groups. However, immediate improvement of the VAS after vertebroplasty was greater in the EVPG ($5.1{\pm}1.3$) than in the DVPG ($4.0{\pm}1.0$, p=0.002). The proportion of cement leakage was lower in the EVPG (30.4%) than in the DVPG (59.3%, p=0.039). In addition, semiquantitative grade of cement interdigitation was significantly more favorable in the EVPG than in the DVPG (p=0.003). Final vertebral body collapse and segmental kyphosis did not differ significantly between the two groups. Conclusion : Our findings suggest that EVP achieves a better immediate surgical effect with more favorable cost-effectiveness.

• 한국전산구조공학회논문집
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• 제31권6호
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• pp.373-380
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• 2018

본 논문에서는 다중적층 유리의 고속 충돌체에 의한 충돌/침투 파괴 현상을 해석하기 위해 페리다이나믹 동적 해석 기법을 적용한다. 대부분의 다중적층 유리 구조물들은 다수의 주요 유리층들이 상대적으로 매우 얇은 탄성 필름으로 접착되어서 만들어진다. 따라서 다중적층 구조물의 수치해석 모델을 구성하는 것은 까다롭고 비용이 많이 든다. 본 연구에서는 실제 절점을 대신하여 가상의 절점들을 주요층들 사이에 위치시키고 상호작용시키는 비국부 가상 층간구조 모델링을 도입하여 보다 효율적으로 다중적층 구조를 모델링하였다. 또한 고속 충돌체와의 충돌 및 침투 현상을 해석하기 위해 페리다이나믹 비국부 접촉 모델이 고려되었다. 7개의 유리층과 하나의 탄성 백킹층이 폴리비닐부티랄 필름으로 부착된 다중적층 유리의 충돌 파괴 해석을 통해 제안된 해석 모델의 손상 파괴 적용 가능성을 확인하였다.

• Journal of Trauma and Injury
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• 제34권2호
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• pp.98-104
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• 2021

Purpose: Severe pelvic fractures are associated with genitourinary injuries, but the relationship between pelvic trauma and concomitant urethral injuries has yet to be elucidated. This study evaluated the incidence, mechanism, site, and extent of urethral injuries in male patients with pelvic fractures. Methods: A retrospective cohort study was performed involving patients with urethral injuries accompanying pelvic fractures who visited Pusan National University Hospital from January 1, 2014 to December 31, 2019. Demographics, mechanisms of injury, clinical features of the urethral injuries, concomitant bladder injuries, methods of management, and the configuration of the pelvic fractures were analyzed. Results: The final study population included 24 patients. The overall incidence of urethral injury with pelvic fracture was 2.6%, with the most common mechanism of urethral injury being traffic accidents (62.5%). Complete urethral disruption (16/24, 66.7%) was more common than partial urethral injuries (8/24, 33.3%), and unstable pelvic fractures were the most common type of pelvic fracture observed (70.8%). There was no definitive relationship between the extent of urethral injury and pelvic ring stability. Conclusions: The present study provides a 6-year retrospective review characterizing the incidence, mechanism, and clinical features of urethral injury-associated pelvic fractures. This study suggests that the possibility of urethral injury must be considered, especially in unstable pelvic fracture patients, and that treatment should be chosen based on the clinical findings.

• Clinics in Shoulder and Elbow
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• 제24권1호
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• pp.9-14
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• 2021

Background: Recent studies about completely displaced midshaft clavicle fractures have reported that their nonunion/malunion rates were significantly higher in conservatively treated patients compared to surgically treated patients. The purpose of this study was to evaluate the factors associated with treatment decisions for midshaft clavicle fractures and also the factors that affect patient satisfaction with their treatment choice. Methods: We retrospectively reviewed the records of 75 patients who had been diagnosed with a midshaft clavicle fracture and were treated conservatively at a single institution between March 1, 2013, and December 31, 2014. Their medical records were reviewed to investigate the severity of the initial vertical displacement. A telephone survey was carried out to identify the presence of any patient-perceived deformity and determine if the patient eventually underwent surgery and whether the patient would prefer surgery if the injury recurred. Results: Significantly more patients with vertical displacement ≥100% (9/28) eventually underwent surgery compared to patients with vertical displacement <100% (3/32, p=0.028). Patients with vertical displacement ≥100% (13/28) were significantly more likely to prefer surgery compared to patients with vertical displacement <100% (7/32, p=0.044). Among the conservatively treated patients, nine of 32 participants with a patient-perceived deformity and one of 16 without a patient-perceived deformity responded that they would prefer to receive surgery in same situation in the future (p=0.079). Conclusions: Patients with a midshaft clavicle fracture with vertical displacement of ≥100% may eventually require surgical treatment. When conservative treatment is carried out, the long-term patient results may be unsatisfactory due to perceived residual deformities.

• 대한한의학회지
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• 제42권2호
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• pp.90-97
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• 2021

DXA로 측정한 요추 부위와 대퇴골경의 골밀도 수치가 2년간 지속적으로 연령대 평균 이하였던 중년의 사무직 남성 환자가 접골탕을 복용하고 골밀도 수치가 개선되었다.

• Archives of Plastic Surgery
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• 제50권1호
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• pp.37-41
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• 2023

Background The coronavirus disease 2019 (COVID-19) outbreak has had a major impact worldwide. Several countries have implemented restrictions on social interaction ("social distancing"). Several studies have reported that the epidemiology of trauma patients, such as those with facial bone fractures, has changed after COVID-19 pandemic. This study aimed to further explore these specific changes. Methods This was a retrospective study of patients who presented to a single institution with facial bone fractures between January 1, 2016, and December 31, 2020. Baseline patient demographics, clinical information, type of fracture, etiology, and operative management were compared before and after COVID-19. Results Of all cases, 3,409 occurred before COVID-19, and 602 occurred after COVID-19. Since the outbreak of COVID-19, the number of patients with facial fractures has not decreased significantly. A significant increase was noted in fractures that occurred outdoors (p < 0.001). However, a decrease was observed in operative management between the groups (p < 0.001). There was no significant difference in the proportion of assault, fall-down, industrial accident, or roll-down. In contrast, the proportion of traffic accidents and slip-down categories increased significantly (p < 0.05). Moreover, a significant decrease was found in the proportion of the sports category (p = 0.001) Conclusions It was confirmed through this study that COVID-19 pandemic also affected epidemiology of facial fractures. Focusing on these changes, it is necessary to develop safety measures to reduce facial fractures.