• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.121-124
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• 2005

This paper was about experimental test properties by mechnical joint of CF1263/Epoxy Al honeycomb panels. In case of mechanical joint using screw, nut shall be secured over than minimize third screw pitch. In case of insert backsheet for increase of joint force, increase weight for assemble by screw pitch. In case of insert backsheet with CF1263/Epoxy, predominant save weight and minimazer of displacement by tensile weight moreover predominant strength. In case of mechanical joint by rivet, rivet of Monobolt has over-hole in hole of CF1263/Epoxy but rivet of PROTRUDING has predominant of mechanical joint.

• 대한족부족관절학회지
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• 제19권4호
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• pp.181-187
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• 2015

Purpose: The purpose of this study is to retrospectively analyze the clinical results of screws and Kirschner wire (K-wire) fixation in patients with fracture dislocation of Lisfranc joint and the consequence of screw breakage. Materials and Methods: Sixty patients underwent Lisfranc joint open reduction and removal of internal fixators from January 2007 to December 2011. Forty-nine cases (81.7%) underwent operations with screw alone, and 11 cases (18.3%) underwent operations with both screws and K-wires. Type of internal fixators, duration of internal fixator removal, breakage of internal fixators and satisfaction with reduction were investigated. Additionally, American Orthopaedic Foot and Ankle Society (AOFAS) midfoot scales were analyzed. Results: The internal fixator was broken in 5 cases (8.3%). The average duration of instrument removal was 154 days in the non-broken screw group and 268.6 days in the broken screw group (p<0.05). The average AOFAS midfoot scale was 77.4 in the non-broken screw group and 74.2 in the broken screw group. The most commonly damaged portion was the first tarsometatarsal (Lisfranc) joint. Conclusion: Treatment with screws and K-wires was effective in patients with fracture dislocation of Lisfranc joint. The appropriate time for screw removal should be considered.

• 대한치과보철학회지
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• 제39권3호
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• pp.297-305
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• 2001

Statement of problem. There have been previous studies about instability according to screw material by means of calculating preload in tightening screw or recording of the torque necessary to loosen screw after tightening screw. Purpose. The purpose of this study was to evaluate screw joint stability through the analysis of fitness at the mating thread surfaces between implant and screw after tightening screws made of different materials. Material and methods. In this study, screws were respectively used to secure a cemented abutment to a hexlock implant fixture; teflon coated titanium alloy screw and titanium alloy screw(Steri-Oss), gold-plated gold-palladium alloy screw and titanium alloy screw(Implant Innovation), gold screw and titanium screw(AVANA Dental Implant System). Each abutment screw was secured to the implant with recommended torque value using a digital torque controller. Each screw was again tightened after 10minutes. All samples were cross sectioned with sandpaper and polished. Then samples were evaluated with an scanning electron microscope analysis. Results. In titanium alloy screw, irregular contact and relatively large gap was present at mating thread surface. Also in teflon-coated titanium screw, incomplete seating and only partially contact was present at the mating thread surface. In gold-plated gold-palladium alloy screw, relatively close and tight contact without the presence of large gap was present by existing of gold coating at the mating thread surfaces. In gold alloy screw, relatively small gap between the mating components was seen. Conclusions. This result suggested that gold plated gold-palladium alloy screw and gold alloy screw achieved a greater degree of contact at the mating thread surfaces compared to titanium alloy screw and teflon-coated titanium alloy screw.

• Journal of the Korean Wood Science and Technology
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• 제19권1호
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• pp.22-30
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• 1991

This study was carried out to determine the Joint characteristic of L-type specimens. L-type specimens were made of two kinds uf solid woods(Antiaris, Sepetir) and three kinds of wood based materials(plywood, particleboard, medium density fiberboard). They were constructed with PVC anchor and screw, and were discussed with joint strength and stiffness coefficients. The obtained results were as follows: 1. Bending strength showed very high increasing rate from one to three used PVC anchor and screw but was a little rise from three to four used PVC anchor and screw in solid wood. However. in wood based materials, it was unchanged without increasing rate or slight decreased from three to four used PVC anchor and screw. 2. The stiffness coefficients, or Z-values, were in the range from $4.704\times10^{-4}$ to $1.864\times10^{-3}$(rad/kgf-cm). They showed $10^{-3}$ level in one PVC anchor and screw but $10^{-4}$ level in two, three. four PVC anchor and screw. Accordingly, they indicated flexible joints in one PVC anchor and screw and relatively stable joints in two, three. four PVC anchor and screw. 3. Measured ultimate bending moments were 258.70kgf-cm in plywood and 142.68kgf-cm in medium density fiberboard. 4. Comparing with dowel joint. the joint strength used PVC anchor screw was inferior to 8mm and 10mm dowel diameter but differ little from 6mm dowel diameter.

• 대한족부족관절학회지
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• 제4권2호
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• pp.61-66
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• 2000

Purpose: To evaluate the clinical validity of percutaneous screw fixation in Maisonneuve fracture. Material and Methods: Out of 5 Maisonneuve fracture patients hospitalized in the department of orthopedic surgery of Seigang hospital from February 1995 to May 1998, 4 patients were treated with percutaneous screw fixation and 1 patient was treated with percutaneous screw fixation and repair of deltoid ligament altogether. The results were evaluated on the clinical and radiological finding. Results: In all cases, the range of motion of ankle joint was normal, the complication such as postoperative pain and post-traumatic arthritis were not found. Widening of medial clear space or talar shift were not found in the follow up X-ray and tibiofibular distance, compared with normal ankle joint was same on follow up CT. Conclusion: Percutaneous screw fixation is simple, less invasive and more effective method in the treatment of Maisonneuve fracture.

• 제어로봇시스템학회논문지
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• 제8권10호
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• pp.881-889
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• 2002

Mobility analysis for various mobile mechanisms including mechanisms with lack of geometric generality is performed. Joint screws are employed to find the sire of feasible joint motion space or each of independent loops of mobile mechanisms. Particularly, the concept of "representative screws" is introduced to represent the feasible motion spaces for subsets of joints belonging to either a loop or a sub-system consisting of several closed loops. Firstly. simplified joint model for each of low different typical wheels popularly employed in mobile robots is described. Then. mobility analysis fir various types of planar mobile robots and the Mars Rover mobile robot for navigation on the rocky road on Mars arc performed. It is confirmed that the obtained results in this study coincide with the previous ones which were obtained by suing imaginary Joints approach(1)pproach(1)

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.421-422
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• 2013

• 대한치과보철학회지
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• 제47권2호
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• pp.125-135
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• 2009

연구목적: 임플란트 치료에서 흔히 발생하는 기계적인 문제점을 하나가 지대주나사의 풀림과 파절이다. 일반적으로 나사 연결의 안정성을 위해서는 지대주나사의 조임회전력에 의한 전하중을 나사의 탄성한계까지 증가시킬 필요가 있다. 그러나 저작운동에 의한 기능부하는 전하중이 가해진 지대주나사에 추가적인 인장력을 가하게 되어 나사의 풀림이나 파절의 가능성을 높인다. 이러한 풀림이나 파절을 방지하면서 동시에 최대의 결합 강도를 가지는 조임회전력을 찾는 연구가 필요하다. 본 연구는 지대주나사의 조임회전력이 임플란트-지대주 연결부 안정성에 미치는 영향을 3차원 유한요소 분석을 통하여 확인하고자했다. 연구 재료 및 방법: External butt joint를 가진 임플란트를 기반으로 3차원 유한요소 해석모형을 설계하였다. 조임회전력에 따른 지대주나사의 전하중을 이론치, 실험치 및 해석치를 비교하여 해석모형을 검증하였다. 검증한 해석모형에서 대해 조임회전력을 10 Ncm, 20 Ncm, 30 Ncm, 그리고 40 Ncm로 각각 적용하고 지대주에 30도 경사지게 250 N의 외부하중을 가하여 유산요소 해석을 실시하였다. 그 결과를 통해 지대주나사의 최대 등가응력을 계산하고 고정체와 지대주 연결부의 응력분포 및 이개거리(gap distance)를 산출하였다. 결과 및 결론: 본 연구조건 하에서 다음과 같은 결과를 얻었다. 1. 전하중은 조임회전력이 클수록 증가하였다. 2. 조임회전력 적용 후 최대 등가응력은 지대주나사 경부에서 발생하였으며, 나사산 체결부에서는 주로 경부쪽 네 개의 나사산에 응력이 집중되었다. 3. 외부하중을 가했을 때에도 조임회전력을 적용했을 때와 동일하게 최대 등가응력은 주로 지대주나사 경부에서 발생하였으나, 10 Ncm의 조임회전력을 적용한 경우에서는 지대주나사 두부밑면에서 발생하였다. 4. 외부하중을 가했을 때 10 Ncm와 20 Ncm의 조임회전력을 적용한 경우에서는 연결부 이개(joint opening) 현상이 관찰 되었다. 5. 조임회전력이 40 Ncm인 경우에는 경사하중에 의해 지대주나사의 경부에 발생하는 최대등가응력이 나사의 소재인 티타늄 합금의 허용응력을 초과하였다. 이상의 결과로 볼 때, 조임회전력은 고정체와 지대주 연결부의 안정성에 영향을 미치는 것이 확인되었다. 임플란트 지대주나사는 임상에서 발생하는 기능 하중을 고려하여 고정체와 지대주 연결의 안정성을 유지할 수 있는 적정 조임회전력의 크기가 제안되어야 한다.

• 대한치과보철학회지
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• 제39권4호
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• pp.366-375
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• 2001

The objective of this study was to investigate the surface contact and screw joint stability between screw and implant interface by use of sealer. The implants evaluated in this study were Steri-Oss futures(Hexlock $3.8D{\times}10mm$: Steri-Oss, Yorba Linda, CA), and Steri-Oss staight abutment. Titanium alloy screws were used to secure abutments to implants. The other titanium alloy screws applicating sealer(Impla-Seal, Implant Support Systems, Inc. Irvine, CA) were used to secure abutments to implants. In one another sample, 6kg of force was applied during simulated intraoral movements after abutment screws were secured to the implants with sealer. All samples were cross sectioned with sandpaper and polished with $0.1{\mu}m\;Al_2O_3$. Then samples were recorded with an scanning electron microscope. The results were as follows : 1. In the case of titanium alloy screw, irregular contacts and relatively large gap were present at thread mating surface. Also abutment screw/implant interface demonstrate incomplete seating and only one surface contact of threads between implant and screw. 2. In the case of titanium alloy screw applecating sealer, sealer was present between implant and screw. Therefore implant and screw had relatively close and tight contact without the presence of large gap. 3. On the other hand, in the case of titanium alloy screw applicating sealer and dynamic loading of suprastructures, sealer was partially present between implant and screw. Conclusively, sealer fills voids, creating a barrier to moisture and bacteria. In addition, loading of suprastructures may change the situation and limit the indications for gap sealing.

• International journal of advanced smart convergence
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• 제4권1호
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• pp.145-153
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• 2015

Friction Stir Welding (FSW) is a solid state welding that could successfully weld the difficult-to-weldmaterials such as an aluminum alloy. In this welding process, the stirrer of the welding tool is one of the important factors for producing the perfect sound joint that indicates the higher joint strength. So, this report aims to apply the friction stir welding using various stirrer geometries to weld the AA6063-T1 aluminum alloy butt joint, investigates the mechanical properties of the joint and then compares the mechanical properties with the microstructure of the joint. An experiment was started by applying the friction stir welding process to weld a 6.3 mm thickness of AA6063-T1 aluminum alloy butt joint. A study of the stirrer geometries effect such as a cylindrical geometry, a cone geometry, a left screw geometry and a right screw geometry at a rotational speed of 2000 rpm and a welding speed of 50-200 mm/min was performed. The mechanical properties such as a tensile strength and a hardness of the joint were also investigated and compared with the microstructure of the joint. The results are as follows. A variation of FSW Stirrer shape directly affected the quality AA6063-T1 aluminum alloy butt joint. A cylindrical stirrer shape and a cone stirrer shape produced the void defect at the bottom part of the weld metal and initiated the failure of the joint when the joint was subjected to the load during the tensile test. Left and right screw stirrer shapes gave the sound joint with no void defect in the weld metal and affected to increase the joint strength that was higher than that of the aluminum base metal.