• 한국콘텐츠학회논문지
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• 제14권11호
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• pp.370-377
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• 2014

최근 3D 프린팅 기술은 다양한 의학 분야에서 활용하고 있으며, 기존의 절삭가공 보다 제작시간과 비용, 과정측면에서 매우 효율적이다. 특히 정형외과에서는 수술시간, 수술 정확성 등의 개선과 환자의 고통 감소와 재수술을 최소화하는 방법으로 관심이 집중되고 있다. 그러나 기존 연구에 사용된 3D 프린터는 하드웨어 및 소프트웨어의 기술적 활용성, 재정적 가용성 등의 문제로 현재 병원에서 일반적으로 널리 사용되지 못하고 있는 실정이다. 본 연구에서는 이를 해결하기 위해 CT 영상을 Open Source DICOM Viewer와 STL 파일변환 프로그램, FDM 와이어 적층가공방식의 조립형 3D 프린터로 골반 골절 모델을 직접 제작하여 비용과 시간을 단축하고 사전 수술계획에 활용하였다. 6명의 불안정성 골반골절 수술환자의 맞춤형 골 모델을 제작한 후 대학병원 정형외과 임상의에게 골절수술 전에 제공하여 임상적 활용 가능 여부에 대한 검토와 분석의견 결과 정밀도, 해상도가 수술계획에 사용하여도 유용한 것으로 판단되었다.

• 대한기계학회논문집A
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• 제25권3호
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• pp.510-519
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• 2001

The tensile and fracture toughness tests have been conducted to investigate the degradations of mechanical properties induced mainly by neutron irradiations in Zr-2.5Nb CANDU pressure tube materials operated in Wolsung Unit-1. the tests were performed at room, 150, 200, 250, 300 $\^{C}$ for the irradiated and unirradiated specimens in hot cell. The specimens were directly machined from the tube retaining original curvature using specially designed electric discharge machine(EDM). From the tensile tests of the irradiated specimens, it was found that tensile strength was increased and total elongation was decreased compared to those of the unirradiated ones. The active voltages in the fracture toughness tests for the irradiated showed the discontinuous abrupt increases caused by crack jumping in lower temperature. In the crack resistance curves we found the stable crack growth in the unirradiated, whereas the unstable and three crack growth stages in the irradiated specimens due to the accumulated irradiation defects. The various fracture characteristic values in the irradiated are remarkably lower than those of the unirradiated. Through the fractography, we found in the irradiated that smaller dimple and shorter fissures than the unirradiated, and that the fractured surface had three regions that were flat, transition and slant/shear area. These can explain the difference in the crack growth characteristic values of the irradiated and the unirradiated ones.

• Clinics in Shoulder and Elbow
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• 제17권1호
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• pp.2-9
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• 2014

Background: Indirect reduction technique offers a valid option in the treatment of proximal humerus fracture. The purpose of this study is to evaluate the functional outcome and the complication rate after indirect reduction and internal fixation of unstable proximal humeral fractures with use of a locking plate. Methods: Twenty four patients with acute proximal humerus fracture were managed with indirect reduction and internal fixation with a locking plate. The mean follow-up period was 15.5 months. Results: The anatomical reduction of the medial cortex buttress was seen in 16 patients (66%) of the Group A and the non-anatomical reduction was seen in 8 patients (33%) of the Group B. Mean union time was $3.2{\pm}1.9$ months; it was $2.2{\pm}0.6$ months in the Group A and $5.3{\pm}2.2$ months in the Group B (p < 0.05). In our series, there were 6 cases of complications and these include 2 cases of varus malunion, 2 cases of shoulder stiffness, 1 case of heterotrophic ossification, 2 cases of screw perforation and 1 case of impingement. Conclusions: We conclude from our studies that indirect reduction and internal fixation using locking plate for acute proximal humerus fracture can give good results with bony union and predictable good overall functional outcome. If the medial cortex buttress is well maintained, a better anatomical reduction would be achieved, the union would be prompted, the pain would be further reduced and the range of the motion would be recovered more promptly.

• 구강회복응용과학지
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• 제30권2호
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• pp.159-169
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• 2014

다발성 안면골절 시 연조직 및 경조직의 소실로 인해 적절한 과두-디스크의 기능을 회복할 위치를 찾는데 어려움이 있다. 다발성 안면골절 및 양측 과두골절과 부족한 수직고경 및 안면비대칭을 가진 환자가 내원하였다. 교합안정장치를 이용하여 골절된 과두를 정복하고 과두-디스크 복합체에 새로운 기능적 위치를 선정하였다. 추적조사를 통해 과두의 위치가 편안감과 안정성이 적절하다고 판단한 뒤 임플란트와 고정성 보철물을 이용한 완전구강회복을 시행하였다. 환자는 심미성과 기능에 만족하였으며 안정적 교합상태를 보였지만 추가적인 교합변화의 가능성을 배제할 수 없기 때문에 야간안정장치 및 정기적인 관리가 필요할 것으로 사료된다.

• Journal of Welding and Joining
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• 제34권2호
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• pp.16-21
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• 2016

Recent keywords of the heavy industries are large-scale structure and productivity. Especially, the sizes of the commercial vessels and the offshore structures have been gradually increased to deliver goods and explore or produce oil and natural gas in the Arctic. High heat input welding processes such as electro gas welding (EGW) have been widely used for welding thick steel plates with flux-cored arc welding (FCAW), especially in the shipbuilding industries. Because high heat input welding may cause the detrimental effects on the fracture toughness of the welded joint and the heat affected zone, it is essential to obtain the sufficient toughness of welded joint. There are well known that the fracture toughness like CTOD, CVN, and KIC were very important factors in order to secure the safety of the structures. Furthermore, the welding residual stress should be considered to estimate the unstable fracture in both EGW and FCAW. However, there are no references on the welding residual stress distribution of EGW and FCAW with thick steel plates. Therefore the welding residual stresses were very important elements to evaluate the safety of the welded structure. Based on the measurement results, the characteristics of residual stress distribution through thickness were compared between one-pass electron gas welding and multi-pass flux-cored arc welding. The longitudinal residual stress in the multi-pass flux-cored arc welding is tensile through all thicknesses in the welding fusion zone. Meanwhile, longitudinal residual stress of EGW is tensile on both surfaces and compressive at the inside of the plate. The magnitude of residual stresses by electron gas welding is lower than that by flux-cored arc welding.

• 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.

• Journal of Trauma and Injury
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• 제29권1호
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• pp.14-21
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• 2016

Purpose: The purpose of this research was to analyze the results of the combined and posterior approaches for treating thoracolumbar and lumbar burst fractures and to find an adequate method of treatment. Methods: We retrospectively analyzed the cases of 46 patients with unstable thoracolumbar and lumbar burst fractures who had been surgically treated. All cases were divided into two groups based on the operation method used. Eleven patients had undergone the combined approach, while 35 patients had undergone the posterior approach. Radiological and clinical evaluations were performed before surgery, after surgery, and at the final follow-up. Results: The stenotic ratios of the area occupied by the retropulsed bony fragments to the estimated area of the original spinal canal were 68.2% and 45.6% for the combined and the posterior approaches, respectively. No significant differences in the neurological improvement or the corrected state of the sagittal index were noted, but the patients who had been treated with the combined approach group had better results than those who had been treated with the posterior approach group in terms of correction and maintenance of the sagittal index. The average kyphosis corrections at the final follow-up were 15.3 degrees for the patients in the combined approach group and 10.0 degrees for those in the posterior approach group. Surgical time and estimated blood loss were all significantly higher for patients in the combined approach group. Conclusion: The combined and the posterior approaches showed similar results in the improvements of the neurologic state and the corrected state of the sagittal index. However, use of the combined approach is recommended for patients with severe kyphosis and with severe canal encroachment.

• Journal of Trauma and Injury
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• 제22권2호
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• pp.254-259
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• 2009

Purpose: Pelvic trauma is a serious skeletal injury with high mortality. Especially in cases of severe injury trauma, treatment outcomes depend on early diagnosis and intervention. We expect trauma surgeon to play an important role in the management of severe multiple trauma patients. Methods: A retrospective study was performed on pelvic trauma patients with hemodynamic instability between March 2005 and September 2009. We divided the time period into period I (March 2005~Feburary 2009) and period II (March 2009~September 2009). The trauma surgeon and team started to work from period II. Data were collected regarding demographic characteristics, mechanism of injury, type of pelvic fracture, ISS(injury severity score), treatment modality, transfusion requirement, time to definitive treatment, and mortality. Results: During period I, among 7 hemodynamically unstable patients, 4(57.1%) patients died. However during Period II, only one of 6(16.6%) patients died. The demographic data and injury scores showed no differences between the two time periods, but the time to definitive treatment was very short with trauma team intervention(14.4 hrs vs. 3.9 hrs). Also, the amount of transfusion was less(41.1 U vs. 13.9 U). With arterial embolization, early pelvic external fixation led to less transfusion and made patients more stable. Conclusion: This study demonstrated the importance of the trauma surgeon and the trauma team in cases of hemodynamically unstable pelvic trauma. Even with the same facility and resources, an active trauma team approach can increase the survival of severely injured multiple trauma patients.

• 한국해양공학회지
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• 제7권2호
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• pp.57-67
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• 1993

The fracture behavior of plain woven glass/epoxy composite plates with a crack is investigated under static tensile loading. It is shown in this paper that the characteristic length associated with the point stress criterion depends on the crack length. To predict the not ched tensile strength, the point stress criterion proposed by Whitney and Nuismer are modified. An excellent agreement is found between the experimental results and the analytical prediction of the modified point stress criterion. The condition of unstable crack growth in the presence of a per-existing flaw(machined notch) is examined by means of the maximum stress intensity factor $K_max$ using maximumload P$_max$. The values of $K_max$ evaluated from energy release rate G$_max$(the compliance me thod) indicate a wide difference. Therefore in regard to anisotropy and heterogeneity of the composite materials studied, the modified shape correction factor f(a/W) is obtained. $K_max$evaluated by the compliance method a little or insignificantly depends on the initial crack length a, the specimen thickness B, the crack angle .theta. and the specimen geometry.

• Clinics in Shoulder and Elbow
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• 제6권1호
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• pp.37-43
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• 2003

Purpose: To evaluate the results in patients who received total elbow replacement for posttraumatic destroyed or unreduced elbow joint. Materials and Methods: Six patients with posttraumatic destroyed, or unreduced elbow joint, who were nearly impossible to move actively and had pain and grossly unstable joint, were followed up average 42 months. 3 cases were soft tissue injuries and bone defects which were caused by severe comminuted fracture, 1 was a nonunion with comminuted fracture, and 2 were unreduced elbow joint. Total elbow replacement was performed average 10 months after the injury. All the cases were used by semiconstrained prosthesis, and the results were estimated by Mayo elbow perfomance score. Results: Pain was decreased in all the cases postoperatively. Average ranges of motion were improved with active extension 20° and flexion 120°. Mayo elbow performance scores were pain 42.5 points, range of motion 17.5 points, stability 8.3 points, function 19.2 points and totally 87.5 points, and final results were 3 excellent and 3 good. Loosening of prosthesis was not found in all the cases by final follow-up radiograph. Conclusicon: Semiconstrained TER can be used as a effective treatment improving pain and active ranges of motion caused by posttraumatic destroyed or unreduced elbow joint, however, long term follow-up is needed because early loosening of TER can be occurred due to severe bone defects.