• The Journal of Korean Academy of Prosthodontics
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• v.45 no.4
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• pp.482-491
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• 2007

Statement of problem: The screws of dental implant, having various thread types, can be categorized into different classes by their geometrical form, and each type transmits dissimilar amount and form of stress to alveolar bone. Purpose: The purpose of this study was to find an inclination angle of the screw thread that is favorable in distributing the stresses to alveolar bone. Material and methods: In this study, We used three dimensional finite element analysis with modeling having three types of thread inclination angles and fixed pitch-0.8 mm (single thread type with $3.8^{\circ}$ inclination, double thread type with $7.7^{\circ}$ inclination, triple thread type with $11.5^{\circ}$ inclination). Results: The results obtained from this study were as follows; 1. When the number of thread increased, the amount of Von-Mises stress was reduced since the generated stress was effectively distributed. 2. Since the maximum principal stress affects on the alveolar bone can influence deeply on the longevity of the implants when comparing the magnitude of the maximum principal stress double thread had least amount of stress. This shows that the double thread screw gave best result. Conclusion: In conclusion, double, and triple thread screws were found to be more effective on distribution of the stress than the single thread screws. But, increasing in the thread inclination angle such as triple thread screw relate on the magnitude of the maximum principal stress affecting on the alveolar bone can become problematic. Thus, effective combination of thread number and thread inclination angle can help prolonging the longevity of implant.

• Journal of Dental Rehabilitation and Applied Science
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• v.21 no.2
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• pp.153-167
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• 2005

The purpose of this study was to compare the v-shape thread with the square shape thread of fixture in the view of stress distribution pattern using finite element stress analysis. The finite element model was designed with the parallel placement of two standard fixtures(4.0 mm diameter ${\times}$ 11.5 mm length) on the region of mandibular 1st and 2nd molars. Three dimensional finite element model was created with the components of the implant and surrounding bone. This study simulated loads of 200 N at the central fossa in a axial direction (load A), 200 N at the buccal offset load that is 2 mm apart from central fossa in a axial direction (load B), 200 N at the buccal offset load that was 4 mm apart from central fossa in a axial direction (load C). These forces of load A',B',C' were applied to a $15^{\circ}$ inward oblique direction at that same site with 200 N. Von Mises stress values were recorded and compared in the supporting bone, fixture, and abutment screw. The following results have been made based on this study : 1. The highest stress concentration occurred at the cervical region of the implant fixture. 2. Von Mises stress value of off-site region was higher than that of central fossa region. 3. Square shape thread type showed more even stress distribution in the vertical and oblique force than V-shape thread type. 4. Stress distribution was the most effective in the case of buccal offset load (2, 4 mm distance from central fossa) in the square shape thread type. 5. V-shape thread type revealed higher von Mises stress value than square shape thread type in all environmental condition. The results from numerical analyses concluded that square shape thread type had the lower destructive stress and more stress distribution between the fixture and bone interface than V-shape thread type. Therefore, square shape thread type was regarded as optimal thread configuration in biomechanical concepts.

• Journal of Korean Dental Science
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• v.5 no.1
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• pp.13-20
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• 2012

Purpose: The purpose of this study was to investigate the effect of patterning on the stress distribution in the bone tissue using the finite element analysis (FEA) model. Materials and Methods: For optimal comparison, it was assumed that the implant was axisymmetric and infinitely long. The implant was assumed to be completely embedded in the infinitely long cortical bone and to have 100% bone apposition. The implant-bone interface had completely fixed boundary conditions and received an infinitely big axial load. von Mises stress and maximal principal stress were analyzed. Conventional thread and 2 or 3 patterns on the upper and lower flank of the thread were compared. Result: The surface areas of patterned implants were increased up to 106~115%. The thread with patterns distributed stress better than conventional thread. Patterning in threads may produce more stress in the implant itself, but reduce stress in the surrounding bone. Stress patterns of von Mises stress were favorable with patterns, while the maximal principal stress was increased with patterns. Patterns in the lower flank showed favorable stress distribution. Conclusion: The patterns in implant thread reduce the stress generated in surrounding bone, but the number and position of patterns were crucial factors in stress distribution.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.4
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• pp.526-543
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• 2000

Finite element analyses were performed to study effects on stress distribution generated in jaw bone for various shapes of dental implants: plateau type, plateau with small radius of curvature, triangular thread screw type in accordance with ISO regulations and square thread screw filleted with small radius partially. It was found that square thread screw filleted with small radius was more effective on stress distribution than other dental implants used in analyses. Additional analyses were performed on the implant with square thread screw filleted with small radius for very-ing design parameters, such as the width of thread end, the height of the thread of the implant and load direction, to determine the optimum dimensions of the implant. The highest stress concentration occurred at the region in jaw Pone adjacent to the first thread of the implant. The maximum effective stress induced by a 15 degree oblique load of 100 N was twice as high as the maximum effective stress caused by an equal amount of vertical load. Stress distribution was more effective in the case when the width of thread end and the height of thread were p/2 and 0.46p, respectively, where p is the pitch of thread. At last, using tensile force calculated from the possible insert torque without breading bone thread, finite element analysis was performed on the implant to calculate pre-stress when the primary fixation of the implant was operated in jaw bone. The maximum effective stress was 136.8 MPa which was proven to be safe.

• Journal of IKEEE
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• v.21 no.1
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• pp.92-95
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• 2017

In this paper, we proposed a way to improve function of small scale GP-GPU. Instead of using superscalar which increase scheduling-complexity, we suggested the application of simple core to maximize GP-GPU performance. Our studies also demonstrated that simplified Stream Processor is one of the way to achieve functional improvement in GP-GPU. In addition, we found that developing of optimal thread-assigning method in Warp Scheduler for specific application improves functional performance of GP-GPU. For examination of GP-GPU functional performance, we suggested the thread-assigning way which coordinated with Deep-Learning system; a part of Neural Network. As a result, we found that functional index in algorithm of Neural Network was increased to 90%, 98% compared with Intel CPU and ARM cortex-A15 4 core respectively.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.2
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• pp.8-16
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• 2000

The thread load distribution as applied to large stud bolts for steam turbines is investigated using the finite element method. The stress concentration in tapered threads is studied with varying prestress and taper angle. Based upon the thread load distribution, the optimal taper angles to reduce the stress concentration are determined for various prestresses. The presented finite element model is validated by comparing results of the calculated thread load with analytic ones. The optimal taper angles obtained from this research can be used in designing tapered threads of large stud bolts for steam turbines.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.1
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• pp.1-10
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• 2013

Purpose: The purpose of this study was to find an inclination slope of the screw thread that is favorable in distributing the stresses to alveolar bone by using three dimensional finite element analysis. Materials and methods: Three types modelling changed implant thread with fixed pitch of 0.8 mm is the single thread implant with $3.8^{\circ}$ inclination, double thread implant with $7.7^{\circ}$ inclination and the triple thread implant with $11.5^{\circ}$ inclination. And three types implant angulation is the $0^{\circ}$, $10^{\circ}$ and $15^{\circ}$ on alveolar bone. The 9 modelling fabricated for three dimensional finite element analysis that restored prosthesis crown. The crown center applied on 200 N vertical load and $15^{\circ}$ tilting load. Results: 1. The more tilting of implant angulation, the more Von-Mises stress and Max principal stress is increasing. 2. Von-Mises stress and Max principal stress is increasing when applied $15^{\circ}$ tilting load than vertical load on the bone. 3. When the number of thread increased, the amount of Von-Mises stress, Max principal stress was reduced since the generated stress was effectively distributed. 4. Since the maximum principal stress affects on the alveolar bone can influence deeply on the longevity of the implants. When comparing the magnitude of the maximum principal stress, the triple thread implant had a least amount of stress. This shows that the triple thread implant gave a best result. Conclusion: A triple thread implant to increase in the thread slope inclination and number of thread is more effective on the distribution of stress than the single and double thread implants especially, implant angulation is more tilting than $10^{\circ}$ on alveolar bone. Thus, effective combination of thread number and thread slope inclination can help prolonging the longevity of implant.

• Journal of the Korea Society of Computer and Information
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• v.15 no.2
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• pp.127-134
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• 2010

In continuous vocabulary recognition system by probability distribution of clustering method has used model parameters of an advance estimate to generated each contexts for phoneme data surely needed but it has it's bad points of gaussian model the accuracy unsecure of composed model for phoneme data. To improve suggested probability distribution mixed gaussian model to optimized that phoneme data search supported configuration thread system. This paper of configuration thread system has used extension facet classification user phoneme configuration thread information offered gaussian model the accuracy secure. System performance as a result of represent vocabulary dependence recognition rate of 98.31%, vocabulary independence recognition rate of 97.63%.

• Transactions of Materials Processing
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• v.19 no.3
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• pp.160-166
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• 2010

In this paper, the process parameters of thread rolling were designed based on the numerical analysis results. Firstly, the effective analysis conditions that guarantee the reliability of the analysis results were found. To find the effective analysis conditions, the analyses were carried out for various numbers of teeth. And then, the effects of the process parameters such as tool shape and temperature on the thread rolling performance were investigated. The formability in thread rolling process was evaluated in terms of Cockcroft-Latham damage value. In order to evaluate formability, Cockcroft-Latham damage value was normalized by the critical damage value which was obtained from the analysis of uniaxial tensile test. The analyses were carried out using DEFORM-3D. The results showed that the flank angle and crest round had an effect on the thread rolling load. It was also shown that temperature had significant effects on the effective strain distribution, rolling load, and damage. With the reduced formability of stainless steel at higher temperature, it was shown that the normalized damage values increased as the process temperature.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.44 no.2
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• pp.59-65
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• 2018

Objectives: This study aimed to optimize the thread depth and pitch of a recently designed dental implant to provide uniform stress distribution by means of a response surface optimization method available in finite element (FE) software. The sensitivity of simulation to different mechanical parameters was also evaluated. Materials and Methods: A three-dimensional model of a tapered dental implant with micro-threads in the upper area and V-shaped threads in the rest of the body was modeled and analyzed using finite element analysis (FEA). An axial load of 100 N was applied to the top of the implants. The model was optimized for thread depth and pitch to determine the optimal stress distribution. In this analysis, micro-threads had 0.25 to 0.3 mm depth and 0.27 to 0.33 mm pitch, and V-shaped threads had 0.405 to 0.495 mm depth and 0.66 to 0.8 mm pitch. Results: The optimized depth and pitch were 0.307 and 0.286 mm for micro-threads and 0.405 and 0.808 mm for V-shaped threads, respectively. In this design, the most effective parameters on stress distribution were the depth and pitch of the micro-threads based on sensitivity analysis results. Conclusion: Based on the results of this study, the optimal implant design has micro-threads with 0.307 and 0.286 mm depth and pitch, respectively, in the upper area and V-shaped threads with 0.405 and 0.808 mm depth and pitch in the rest of the body. These results indicate that micro-thread parameters have a greater effect on stress and strain values.