• 대한기계학회논문집B
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• 제38권7호
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• pp.601-605
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• 2014

일반적으로 표면적/부피비가 큰 전도성 다공체는 수퍼캐패시터의 전극이나 흡수제, 유연히터 등의 다양한 분야에 적용되어 왔다. 본 논문에서는 이러한 전도성 다공성 구조의 역학적 전기적 특성을 이용하여 고감도 압력센서를 구현하였다. 탄소나노튜브 용액에 스펀지를 적셔 다공체에 전도성을 부여하였으며, 압력에 따른 전도성 다공체의 저항 변화를 측정하였다. 전도성 스펀지에 압력이 가해졌을때, 각각의 탄소나노튜브들은 서로 맞붙게 되어 저항이 최대 20%까지 줄어듦을 확인하였다. 부드럽고 탄성력이 뛰어난 탄소나노튜브 스폰지는 반복적인 압축실험에도 모양의 변형 없이 매우 빠르게 안정화되고 일정한 저항변화를 확인할 수 있었다. 또한 스펀지 압력소자를 유연소자에 적용하기 위하여 탄소나노튜브 트랜지스터와 연결하여 외부압력에 따른 전기적 특성변화를 측정하였다.

• 소성∙가공
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• 제21권3호
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• pp.179-185
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• 2012

In this paper, it is proposed to produce high precision screws with a diameter of $800{\mu}m$ and a thread pitch of $200{\mu}m$ ($M0.8{\times}P0.2$) by means of a cold thread rolling process. In this part II of the study, the focus is on the production and reliability testing of the prototype $M0.8{\times}P0.2$ micro-screw. Designs for two flat dies were developed with the aid of the literature and previous studies. Process parameters during the cold thread rolling process were established through FE simulations. The simulation results showed that the threads of the micro-screw are completely formed through the rolling process. Prototype $M0.8{\times}P0.2$ micro-screw were fabricated with a high precision thread rolling machine. In order to verify the simulation results, the deformed shape and dimensions obtained from the experiment were compared with those from the simulations. Hardness and failure torque of the fabricated micro-screw were also measured. The values obtained indicate that the CAE based process design used in this paper is very appropriate for the thread rolling of micro-sized screws.

• 대한족부족관절학회지
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• 제8권2호
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• pp.191-194
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• 2004

Purpose: Anatomic configuration of the ankle joint is useful information during various ankle procedures. This study was prospectively designed to investigate the sagittal inclination pattern of the ankle joint. Materials and Methods: Lateral standing ankle radiographs from one-hundred people (age: $17{\sim}68$, M:F=45:55) and magnetic resonance (MR) sagittal ankle images from twenty-four people (age: $16{\sim}65$, M:F=14:10) were studied. Post-traumatic, arthritic, or grossly deformed ankles at any reason were excluded. The posterior inclination angle (PIA) of the distal tibia was measured and compared between the lateral and the medial segment. Results: On plain radiographic data, the average PIA of the distal tibia was $6.14^{\circ}{\pm}3.56^{\circ}$ (range $0^{\circ}$ to $14^{\circ}$) in the lateral segment and $13.16^{\circ}{\pm}3.05^{\circ}$ (range $6^{\circ}$ to $22^{\circ}$) in the medial segment. On MR imaging data, the average PIA of the distal tibia was $5.08^{\circ}{\pm}4.26^{\circ}$ (range $1^{\circ}$ to $10^{\circ})$ in the lateral segment and $10.16^{\circ}{\pm}4.87^{\circ}$(range $5^{\circ}$ to $17^{\circ}$) in the medial segment. The PIA between two segments was significantly different. Conclusion: The sagittal configuration of the medial area ankle joint and the lateral area ankle joint has difference in the degree of posterior inclination and shape of curvature.

• 복식
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• 제2권
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• pp.35-50
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• 1978

This paper is an observation on the woman's warming hoods such as Nambawi, Pungchae, Ahyam, Jnbawi and Gullae worn form 1800's through 1930's. At the late era of Chosun dynasty, The every day lifes of people were greatly influenced by invasion of western world, in particular the styles of clothing are changed from original one to Western-like. So the hoods of our own's were dissappcared gradually, and the interests of them were reduced accordingly by the western culture invaded. Therefore this paper is intended to participate in the study of clothing culture by considering of hoods, one of the almost disappeared clothes, and review the wisdom and sense of beauty of our ancestor by unique ornament. The warming hoods in this paper are from a category of ear-protection gear and also deformed from man's one. The ear-protection gear was a warming hood from Tae Jong, the king of the early era of Chosun, and usage classifications of them were strict according to the class division at the early and mid era of Chosun, but generally diminised at the late era, thery were used freely, but the differences in decorations represented the division of the rich and poor. General feature of it is open top, but covers all of head and is used for warming clothes, with has many decorations on it, this decorative tendency was more clear at the late era. Namely, the shape had been modified from tough one to modish one, and fur, the material of it, are from stiff and long to soft short and well refined. This warming hoods were used until 1930's then disappeared by the population of western mufflers and wraps. Jobawi is now already forgotten even its name except for the ornament in picturing the baby in first birth day. In revewing the consideration of warming hoods mentioned. It is found that the subtlety of the ancestor, and there are supplication for the happiness of life even in the decorations.

• 대한토목학회논문집
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• 제31권4A호
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• pp.279-286
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• 2011

FRP 긴장재는 PS 강연선의 부식 문제를 해결하기 위한 대안으로써 사용될 수 있으며, FRP 긴장재의 재료특성(부착강도, 인장강도, 전달길이 등)은 구조물에 적용하기 위해서 결정되어야 한다. 재료특성 중에 부착은 FRP 긴장재로 긴장된 PSC 구조물에 적용하기 위해 명확하게 요구되어야 한다. 이 연구는 다양한 표면형상을 갖는 FRP 보강재의 부착특성을 연구하였다. 콘크리트의 철근과 강연선 대신에 사용되는 FRP 재료의 부착특성을 결정하기 위해 CAN/CSA S806-02에서 제안된 직접인발 시험을 수행하였다. 강연선, 이형 철근, 6가지 다른 표면 형상을 갖는 탄소 또는 유리섬유 FRP 보강재에 대하여 총 40개의 시편이 제작되었다. 부착실험 결과 각 실험체의 다양한 부착응력-슬립 곡선을 나타냈고, 국내에서 제작된 CFRP 긴장재의 부착특성과 비교하였다.

• Structural Engineering and Mechanics
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• 제62권6호
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• pp.749-758
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• 2017

In structural mechanics, traditional analyses methods usually employ matrix operations for obtaining displacement and internal forces of the structure under the external effects, such as distributed loads, earthquake or wind excitations, and temperature changing inter alia. These matrices are derived from the well-known principle of mechanics called minimum potential energy. According to this principle, a system can be in the equilibrium state only in case when the total potential energy of system is minimum. A close examination of the expression of the well-known equilibrium condition for linear problems, $P=K{\Delta}$, where P is the load vector, K is the stiffness matrix and ${\Delta}$ is the displacement vector, it is seen that, basically this principle searches the displacement set (or deformed shape) for a system that minimizes the total potential energy of it. Instead of using mathematical operations used in the conventional methods, with a different formulation, meta-heuristic algorithms can also be used for solving this minimization problem by defining total potential energy as objective function and displacements as design variables. Based on this idea the technique called Total Potential Optimization using Meta-heuristic Algorithms (TPO/MA) is proposed. The method has been successfully applied for linear and non-linear analyses of trusses and truss-like structures, and the results have shown that the approach is much more successful than conventional methods, especially for analyses of non-linear systems. In this study, the application of TPO/MA, with Harmony Search as the selected meta-heuristic algorithm, to cables net system is presented. The results have shown that the method is robust, powerful and accurate.

• 전산구조공학
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• 제8권4호
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• pp.75-85
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• 1995

본 연구의 목적은 부착되어 있거나 혹은 부착되어 있지 않는 텐돈을 갖고 있는 프리스트래스트 콘크리트 구조체의 해석이 가능한 프로그램을 개발하는데 있다. 이를 위해서 먼저 콘크리트, 철근, 그리고 텐돈등의 반복하중에 대한 모델을 선정 개발하고, 텐돈이 부착되어 있지 않는 경우에 그 응력 및 변형도를 보다 정확하게 해석할 수 있는 복합유한요소법을 유도하였다. 이러한 복합 유한요소법을 사용하였을때 요소의 변형 형상을 가정하지 않고도 각 단면들의 변형을 결정할 수 있어 요소의 길이가 기존의 유한요소법에 비하여 상당히 길어질 수 있다. 이러한 복합유한요소법을 가능하게 하기 위해서 다양한 형태의 적분 방법이 프로그램되었다. 그리고 텐돈이 부착되어 있지 않는 경우 그효과를 예측할 수 있는 방법이 개발되었다. 끝으로, 실제 구조체에 대한 해석결과 및 실제시험에 대한 해석결과를 비교하여 프로그램의 적용성을 검토하였다.

• 대한족부족관절학회지
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• 제15권3호
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• pp.139-143
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• 2011

Purpose: The purpose of this study was to introduce the 'Matrixplasty' for the treatment of a severely incurved toenail with growth plate deformity and to report our results treating this disease entity. Materials and Methods: Between January 2010 and May 2010, 48 consecutive patients (62 cases) underwent treatment of symptomatic incurved toenails with the 'matrixplasty'. The mean period of time at last follow-up was $14.0{\pm}1.3$ months. The recurrence rate and complication rate were evaluated. An American Orthopedic Foot and Ankle Society (AOFAS) forefoot hallux score was assigned and patients were evaluated at pretreatment and the last follow-up meeting. For evaluation of improvement in toenail shape, the center to edge angle of the toenail was measured at pretreatment and last follow-up. Results: All ingrown toenails healed and the nail deformity was corrected within 3 weeks after the procedure. Among the 62 cases, four cases had recurred by the last follow-up. The mean pretreatment AOFAS forefoot hallux score was $73.1{\pm}12.8$, and it improved to $98.7{\pm}1.1$ by the last follow-up (p<0.01). The mean center to edge angle of the toenail improved from $53.3{\pm}12.9$ degrees to $18.2{\pm}7.4$ degrees by the last follow-up (p<0.01). Minor paronychia, which was managed with local wound dressing and oral antibiotics, was identified in eight cases. Conclusion: Matrixplasty showed excellent clinical results in the treatment of severe incurved toenail (pincer nail) and this procedure also showed great improvement of the deformed toenail and its growth plate.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제13권2호
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• pp.199-202
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• 1991

이부는 안면 외모에서 뚜렷한 부위를 차지하고 있어 사람의 특징을 나타내며 인상을 결정짓는다 할 수 있겠다. 따라서 옛부터 이 부위는 안면 미용에서 관심의 대상이 되었고 이에 대한 성형 수술도 시행되었다. 그러나 요즘 시행되는 Genioplasty는 짧은 역사를 가졌을 뿐만 아니라 방법도 부위 및 구조적 특성 등으로 다양성이 제한되었다. 기존의 Horizontal reduction genioplasty는 턱이 정상적인 형태 및 전방폭을 가졌을 때에 이부의 높이를 줄이거나 후방위치시킬 때에는 좋은 효과를 볼 수 있으나 하악골의 전방 폭경 및 높이의 결손등이 있을 때에는 mental foramina의 위치, 전방 하악골의 높이와 치근의 위치 등에 의해 사용이 제한된다할 수 있다. 따라서 이러한 환자에 있어서는 다른 방법이 요구된다 하겠다. 본 교실에서는 Hinds와 Kent에 의해 서술된 Horizontal step osteotomy for advancement genioplasty에 대해 변형된 방법으로 narrow, pointd chin과 짧은 전방하악골 높이를 가진 chin prominence환자에 대해 시술한 바 비교적 양호한 결과를 얻었기에 이에 보고하는 바이다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권5호
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• pp.337-342
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• 2012

The osseous or osteocutaneous free fibula flap has become the gold standard for most mandibular reconstructions because of its favorable osseous characteristics. However, disadvantages, such as the time-consuming reconstructive step, difficulty in performing the osteotomies to precisely recreate the shape of the missing segment of mandible and poor bone-to-bone contact play a role in making the surgeons look for alternative flaps. With the advent of computerized design software, which accurately plans complex 3-dimensional reconstructions, has become a process that is more efficient and precise. However, the ability to transfer the computerized plan into the surgical field with stereolithographic models and guides has been a significant development in advancing reconstruction in the maxillofacial regions. The ability to "pre-plan" the case, mirror and superimpose natural structures into diseased and deformed areas, as well as the ability to reproduce these plans with good surgical precision has decreased overall operative time, and has helped facilitate functional and esthetic reconstruction. We describe a complex case treated with this technique, showing the power and elegance of computer assisted maxillofacial reconstruction from the University of Michigan, Oral and Maxillofacial Surgery.