• Maxillofacial Plastic and Reconstructive Surgery
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• 제27권2호
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• pp.160-163
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• 2005

This study was designed to assess skeletal stabilily after surgical correction of mandibular prognathism by bilateral saggital split ramus osteotomy(BSSRO) and fixation with absorbable screws. From July 2001 to September 2003, 30 patients with Class III malocclusion were treated with BSSRO and mandibular setback. They underwent fixation with Biosorb$^{TM}$ FX screws. Cephalograms were obtained preoperatibely, 2 or 3 days postoperatively, and about 12 months after the operation. Changes in the position of lower incisor tip, B point, and pogonion were examined on lateral cephalograms. The mean mandibular setback just after surgery was 10.6mm. 12 months after surgery, mean relapse at pogonion represented 17.9% and 15.1% at B point. Our results suggest that fixation of the bony segments with absorbable screws after BSSO may be used effectively in properly selected cases.

• Archives of Plastic Surgery
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• 제38권4호
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• pp.555-558
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• 2011

Purpose: It is relatively unusual that infraorbital rim fracture is accompanied by nasal bone fracture. In order to correct effectively, subciliary approach and intranasal manipulation are applied simultaneously. But if reduction is not successful, intranasal manipulation may become aggressive and this often causes complications. We introduce a method using intermaxillary fixation screws for decreasing such complications and effective reduction of fracture. Methods: Total seven patients with fracture of frontal process of maxilla were treated with this method. The fracture site was exposed through the subciliary approach, and one or two screws were inserted into the displaced fracture fragment. During the traction of the screws using the wire, the fracture fragment was pushed upward from the intranasal side using an elevator supplementarily and fixed with a plate and the screws. Results: In all patients, the fracture fragment was reduced successfully and no complication occurred during one year's postoperative follow-up. Conclusion: When reduction cannot be attained through a bone hook or an elevator alone, reduction of fracture fragment can be done easily using intermaxillary fixation screws. This method is less likely to cause a mucosal injury because intranasal manipulation is not aggressive. Furthermore, as the screw can be inserted and removed easily, this method is considered effective not only for fracture of frontal process of maxilla but also for fractures in other regions.

• Archives of Plastic Surgery
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• 제38권4호
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• pp.458-464
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• 2011

Purpose: Metacarpal fractures are common hand injury that may require operative intervention to ensure adequate reduction and stabilization. Traditionally, titanium miniplate was used for rigid fixation of bone fractures. However, the use of permanent plate lends itself to multiple complications such as infection, exposure of the hardware, tendon adhesions, tendon rupture, prolonged pain, bony atrophy and osteoporosis (stress shielding), metal sensitization, and palpation under the skin. This study evaluated the usefulness and stability of biodegradable plates and screws for treatment of metacarpal bone fractures. Methods: There was 17 patients who had surgery for metacarpal bone fracture from April 2007 to June 2010. All patients had open reduction and internal fixation. We used absorbable plates and screws (Inion CPS$^{(R)}$) for internal fixation. Postoperative results were assessed with x-ray. Stability of plates and screws, healing process and its complications were observed by clinical and radiographic assessment. Results: All patients were successfully reduced of bone fracture, and fixations with absorbable plates and screws were stable. The mean follow up period was 7.1 months. 2 patients complained postoperative pain, but they were relieved with analgesics. All patients experienced transient stiffness, but they were relieved with active assistive range of motion after removal of splint. No patients suffered complications which could be occurred by using metallic plate. Conclusion: There was no critical complications such as re-fracture or nonunion among patients. No patients suffered side effects related with metallic implants. Biodegradable implants can offer clinically stable and attractive alternative to metallic implants to stabilize metacarpal bone fractures in the hand.

• 대한금속재료학회지
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• 제49권12호
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• pp.983-988
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• 2011

Failure analyses of the screws in spinal fixation devices were carried out. The fractured screws were retrieved from a patient who had spinal surgery in the thoracic vertebrae from number 10 to 15. The failure occurred one month after the removal of the braces. Microstructures and fracture surfaces were examined by optical and scanning electron microscopy. The microstructures of the screws corresponded to annealed Ti-6Al-4V bar. However, in the vicinity of the screw surface, there was an insufficient number of fine precipitates. Fracture surfaces showed typical fatigue failure modes. Regarding the fact that no machining defects were detected, fatigue crack initiation might have been caused by the lack of precipitates near the screw surfaces. Only the fourth of five fixed screws was severely stress-concentrated by the action of the spinal bones, while the stress of the 4th screw was decreased to half of its acceptable level when the screw was supplemented by one more, which might have been fixed in the 6th vertebra under the 5th position by the switching of its position. The stress simulation was conducted by ANSYS with 3D CAD of PRO/E in order to understand the stress concentration behavior and to provide an effective spinal surgery guide.

• Tribology and Lubricants
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• 제24권1호
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• pp.14-20
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• 2008

In this paper, the characteristics of trapezoidal air screws is studied. These screws can e applied to the elevator having column driving shaft. The generalized coordinate transformation technique is used to solve incompressible Reynolds' equation because the air lubricated plane is twisted. The transformed equation is discretized by the base of Finite difference method. Using Visual C++ language, a GUI program which can calculate he load carrying capacity for this kind of air screw is developed, then the design variables for these air screws is studied.

• 대한관절경학회지
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• 제2권1호
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• pp.59-63
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• 1998

There have been numerous methods to obtain a stable arthrodesis of the tibiotalar joint. However, a controvercy has arisen over the most successful and reproducible method to obtain an arthrodesis. The objective of this report is to show that an ankle arthrodesis can be performed successfully and advantageously by using cannulated screws under arthroscopic control and that our csaes will be a part of the multicentric study of arthroscopic ankle arthrodesis in korea. Between May 1996 and May 1997, we perfomed 3 ankle arthrodesis under arthroscopy using cannulated screws. Two patients had post-traumatic osteoarthritis and one had rheumatoid arthritis. Clinical ankylosis in one case and radiological union in two cases were obtained in 12 weeks postoperatively. We propose that arthroscopic ankle arthrodesis is effective procedure in patient who has minimal deformity and bone loss, advantages like small incision, minimal morbidity, low infection rate and rapid return to normal daily activity, but more cases and comparision with open tecnique will be needed.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 The 8th Asian Symposium on Precision Forging ASPF
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• pp.198-201
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• 2003

The multi-action forging process is one of developing directions of forging technologies. In this study, the multi-action die is designed and developed by the screws mechanism and the forging simulation is conducted by using plasticine to investigate the optimum conditions for the design of the screws. The results show the design variables are optimum when the diameter is 30 mm and the screw angle is $60^{\circ}$ for the upper screw rod and the outer diameter is 60 mm and the screw angle is $23.4^{\circ}$ for the lower screw tube. It makes the relative velocity between the upper punch and the die to be two to one, which is the expected condition. The material flow of the plasticine forgings is uniform. Therefore, it is feasible to use the screw set as the multi-action mechanism for controlling the movement of the multi-action forging die set.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.894-899
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• 1997

Genernally, the life of ball screws is presented in catalogue of domestic manufacturer by the name of dynamic load capacity. But, systematic experiment method and reliable data are not secured, even now. Data presented in catalogue is obtained at already established life expression of ball-bearing. Therefore studying on the life of ball screws, characteristic qualities of ball screw must be considered. We studied systematic experiment method and by this do experiments, obtained data. This paper present above items, and expression of life prediction by experiment results.

• 한국생산제조학회지
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• 제9권3호
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• pp.169-177
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• 2000

In machining screws which are important members in mono pumps or progressive cavity pumps CNC turning center with 3 axes is usually used. This sort of screw machining requires large amount of CL data points and rotational tools are used in machining. When working out the CL data points consideration of possible tool interference is important in order to avoid undercut. This paper describes the checking methods of tool interference in the screw machining on the CNC turning center. First of all a specific shape of a screw cross-section that could commonly be applied to all screws was chosen and then possible tool interference associated with that shape was identified. Checking method was mathematically developed and verified. This checking method will be utilized in the CAM system developed by the authors for screw machining on the 3-axis CNC turning center.

• 한국생산제조학회지
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• 제23권2호
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• pp.164-172
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• 2014

This paper presents a method for analyzing the stiffness of full and low DOF (degree of freedom) planar parallel manipulators with serially connected legs. The individual stiffness of each leg is obtained by applying reciprocal screws to the leg twist using passive joints and elastic elements consisting of actuators and links. Because the legs are connected in parallel, the manipulator stiffness is determined by summing the individual leg stiffness values. This method does not require the assumption that springs should be located along reciprocal screws and is applicable to a planar parallel manipulator with a generic or singular configuration. The stiffness values of three planar parallel manipulators with different DOFs are analyzed. The numerical results are confirmed using ADAMS S/W.