• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제27권2호
• /
• pp.111-117
• /
• 2001

There are three designs of thread form in screw type implants: V-thread, Reverse buttress thread and Square thread. The purpose of this study was to find out how thread form designs have an influence on the equivalent stress, equivalent strain, maximum shear stress and maximum shear strain and which design of thread form generates more maximum equivalent stress and strain. 3-D finite element analysis was used to evaluate the stress and strain patterns of three tread types. The results of this study were as follow. 1. Under the 200N of axial load, the value of maximum equivalent stress is smallest in square thread and there is no significant difference between that of V thread and reverse buttress thread. 2. Under the 200N of axial load, the value of maximum equivalent strain is largest in V thread and smallest in square thread. 3. Under the 200N of axial load, the value of maximum shear stress is smallest in square thread and there is no significant difference between that of V thread and reverse buttress thread. 4. Under the 200N of axial load, the value of maximum equivalent strain is largest in V thread and there is no significant difference between that of square thread and reverse buttress thread. 5. Above results show that the square thread has special advantages in stress and strain compared with other thread types, especially in shear stess which is most determinant to implant-bone interface. Considering the superior biomechanical properties of square form implant, we presume that square form implant has better clinical results than the other types of implants in the same clinical conditions.

• Composites Research
• /
• 제17권2호
• /
• pp.15-20
• /
• 2004

나사산을 가지는 구조재료는 높은 전단 응력을 한 방향으로 전달해 주는 용도로 많이 사용되며, 이를 응용하여 고속의 충격에너지나 전단하중에 견별 수 있는 기어 모양의 부품 등 항공 및 군수용 재료에 적용되어왔다. 최근에는 재료를 보다 경량화 하려는 노력의 일환으로 기존의 금속재료를 섬유강화 고분자 수지계 복합재료로 대체하기 위한 연구가 활발히 진행되고 있다. 본 연구에서는 탄소섬유/열경화성 수지계 복합재를 사용하여 나사산(groove)을 가지는 시편을 제작한 뒤 역탄도 기법으로 고속변형 특성 평가를 실시하였고, 이를 통하여 군수용 부품 재료로의 적용 가능성을 타진해 보았다.

• Structural Monitoring and Maintenance
• /
• 제6권2호
• /
• pp.103-124
• /
• 2019

Present study concerns the safety evaluation of SefidRud dam's block No. 18 regarding probable crack propagation in the foundation gallery under a MCE record. Accordingly, a 3D finite element model of the block in companion with the reservoir and the foundation is modeled. All the associated thermal and structural parameters are derived via calibration with the records of thermometers and pendulums installed inside the dam body. The origination of the cracks and their whereabouts are determined by primary thermal and static analyses and through a linear dynamic analysis the potential failure zone and their extent and level are studied. The foundation gallery is the most probable zone among the other intensive tensile stress area to compromise the dam stability. Therefore, the nonlinear analysis of this risky region is inevitable. The results depict the permissible expansion of the cracks inside the gallery even under another future earthquake in MCE level. As a consequence, the general dam performance is assessed safe in spite of the seepage flow rate growth from the gallery fractures.

• 대한족부족관절학회지
• /
• 제10권2호
• /
• pp.213-217
• /
• 2006

Purpose: To evaluate the clinical and radiological results of tibio-talo-calcaneal arthrodesis using ipsilateral distal fibula buttress which had advantages of extended operative field and release of contracted soft tissue. Materials and Methods: We retrospectively reviewed 4 postraumatic compartment syndrome, 2 residual poliomyelitis, 1 posttraumatic osteoarthritis with subtalar joint infection and 1 posttarumatic sciatic nerve palsy patients who underwent a tibio-talo-calcaneal arthrodesis from April, 1996 to March, 2002. Each of the cases was notable for a severe rigid equinovarus, persistent pus drainage of calcaneal area and paralytic foot. The mean duration of follow up was 18 months (range, $13{\sim}42$ months). The pain, function and alignment were evaluated by the modified ankle hindfoot scale of the American Orthopaedic Foot and Ankle Society (AOFAS) and patients satisfaction clinically. The radiological union were evaluated by plain AP and lateral radiographs. Results: The AOFAS score improved from 58 points (range, $47{\sim}78$) preoperatively to 82 (range, $60{\sim}89$) postoperatively. Patents satisfaction checked at 12 months after operation had favorable results (excellent and good 80%). Union rate was 100% radiographically and the mean duration of union was 12.5 weeks (range $8{\sim}22$ weeks). There was 2 cases of superficial pin tract infection and one protrusion of screw. Conclusion: Tibio-talo-calcaneal arthrodesis using ipsilateral distal fibula buttress was good modality of arthrodesis which provides wide operative field and release of contracted soft tissue in some cases of contracted foot.

• 한국농촌건축학회논문집
• /
• 제14권4호
• /
• pp.67-76
• /
• 2012

The main purpose of this study is to understand the existing and the architectural characteristics of the Secondary Stations of Catholic Church in Jeju. The method of this study is to research all the literature and to visit. The time of establishment of the Secondary Stations of Catholic Church in Jeju was mostly 1950's, and that time was the heyday of the Secondary Stations of Catholic Church that was built in Korean. Catholicism was spread throughout Jeju during this time, and in the process, the Secondary Stations of Catholic Church was built. The Secondary Stations of Catholic Church in Jeju are sited mostly in coastal villages, and especially Catholicism was actively spread throughout the west of Jeju and the a large number Secondary Stations of Catholic Church were built in the west of Jeju. The Secondary Stations of Catholic Church were built between the mid-1950's to the mid-1960's. The plan type is kept as plan shaped of straight shape. When made an enlargement of the interior space and altered, framework of the Secondary Stations of Catholic Church was generally maintained. The head of the side window and the front door have the same design characteristics. When the belfry is located, it is attached to an outer wall of the Secondary Stations of Catholic Church, or is located to the left or the right the front of the Secondary Stations of Catholic Church. The design of belfry found expression in various forms. The buttress are not located in the others but in Young-su Gong-So, and it has not the structural functions but the design functions.

• 대한두개안면성형외과학회지
• /
• 제10권1호
• /
• pp.1-6
• /
• 2009

Purpose: This study presents a classification of pure medial and inferior blow-out fracture, and confirms the relationship between the types of fractures, postoperative complications and operative methods. Methods: Sixty patients were treated by transnasal endoscopic reduction with $Medpor^{(R)}$ implantation through subciliary incision and foley catheter insertion into maxillary sinus was done if there was extensive orbital floor fracture. Fractures were classified by number of coronal sections from posterior margin of fossa for lacrimal sac to orbital apex in CT. Type I is defined when the medial wall fracture is over 50% and inferior wall fracture below 50%. Type II, when below 50% medial wall fracture and over 50% floor fracture were present. If there were both over 50%, it was classified as Type III and both below 50% for Type IV. Extreme fracture involving orbital buttress was Type V and postoperative findings in all patients were examined. Results: Type I and V were most common and preoperative findings were more likely to present according to extent of inferior fracture. Diplopia remained in 2 cases after additional insertion of foley catheter, but enophthalmos over 2 mm were presented in 3 cases and diplopia in 3 cases were observed who were not treated with foley catheter. Conclusion: Postoperative complications were increased according to extent of fracture, especially buttress involvement. Additional insertion of foley catheter proved its effectiveness in decreasing postoperative complications.

• Clinics in Shoulder and Elbow
• /
• 제17권1호
• /
• pp.2-9
• /
• 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
• /
• 제23권4호
• /
• pp.313-326
• /
• 2007

With rising prevalency of mouth breathing children caused by developing civilization and increasing pollution, there are many maxillary transverse discrepancy patients with undergrowth of maxilla. For improving this, maxillary mid-palatal suture splitting was often performed. The purpose of this study was to analyse the stress distribution on the craniofacial suture and cranium after rapid maxillary expansion by finite element model. The boy(13Y6M) was chosen for taking computed-tomography for finite element model. Three-dimensional model of maxilla, first premolar, first molar, buccal and lingual part of rapid maxillary expansion were constructed. 1. The alveolar bone adjacent to the first molar and the first premolar that was affected directly by rapid maxillary expansion was displaced laterally approximately 4.04mm at maximum. The force decreased toward anterior region and frontal alveolar bone displaced laterally about 3.18mm. 2. A forward maximum displacement was exhibited at zygomatic process middle region. 3. At maximum, maxillary median part experienced 0.973mm downward repositioning and 0.65mm upward repositioning at lateral alveolar bone. 4. Von mises stress was observed the largest stress distribution around teeth and zygomatic buttress. 5. The largest tensile force was observed around alveolar bone of teeth, while compression force was observed at zygomatic buttress.

• 한국전산구조공학회논문집
• /
• 제24권4호
• /
• pp.449-455
• /
• 2011

최근 가압중수형 원전 격납건물의 내압능력 및 비선형 거동에 관한 실증실험과 해석코드에 대한 검증을 위하여 인도의 BARC 주관으로 가압중수형 격납건물 1/4 축소모델을 건설하였고, 내압성능평가를 위한 국제공동연구가 수행되었다. 이 논문은 가압중수형 1/4 축소모델 격납건물에 대한 내압성능과 비선형 거동을 예측하기 위하여 유한요소해석을 수행하였고 그 결과를 도출하였다. 대상 격납건물은 기초매트와 원통형 벽체 및 돔으로 구성되어 있고, 수평 텐던의 정착을 위하여 4개의 부벽(buttress)을 가지고 있다. 유한요소해석을 위하여 ABAQUS를 이용하였고 콘크리트, 철근 및 텐던에 대한 유한요소 모델을 작성하여 극한내압해석을 수행하였다. 유한요소해석결과 콘크리트의 초기 균열은 $1.6P_d$(design pressure)에서 발생하였고, 철근의 항복은 $3.36P_d$ 그리고 극한내압능력은 $4.0P_d$ 수준으로 나타났다.

• 대한정형외과학회지
• /
• 제55권3호
• /
• pp.193-199
• /
• 2020

골수강 내 금속정(골수정)은 1988년부터 대퇴골 전자간 골절을 치료하는 데 사용되어 왔다. 골수정은 활강고나사와 같은 골수강 외 고정 장치에 비하여 기계적 이점이 있으나 대퇴 전자간 골절 Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) 31-A1 및 31-A2 골절 치료에 활강고나사보다 유리한 고정 기구인지에 대해서는 논란이 계속되고 있다. 지난 30년 동안 여러 시행 착오가 극복되었고 새로운 유형의 대퇴 골수정이 개발되어 임상에서 사용되고 있다. 새로 개발된 골수정은 삽입 과정이 쉬워지고 지연나사를 사용한 대퇴 골두의 고정 능력이 향상되어 왔다. 그러나 고정 실패율은 여전히 정형외과 의사의 수술 술기에 달려 있다고 할 수 있다. 이 종설에서 우리는 골수정을 이용하여 대퇴 전자간 골절을 치료하는 동안 내측 지지대 복원의 중요성에 대해 초점을 맞추고 그 기본 원칙에 대하여 논의해 보고자 한다.