• Journal of the Korean Institute of Gas
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• v.22 no.1
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• pp.60-63
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• 2018

This paper presents the FEM analysis results on the strength safety of a gas valve for a LPG cylinder. Based on the FEM analysis, the maximum von Mises stress on the boundary zone between a safety valve and the upper area of the thread is 99.2 MPa for the supplied gas pressure of 3.5 MPa in which the gas valve is fully opened. The maximum von Mises stress of 99.2 MPa is considered as safety value, because that value is lower than the yield stress of a brass material. In this case, the maximum deformation at the upper right part of the pressure regulator is 0.002mm. The maximum deformation zone is not a meaning part of the sealing part such as an O-ring or a diaphragm of a gas valve and a pressure regulator. The proposed hybrid gas valve model in which is integrated with a conventional cut-off valve and a pressure regulator is recommended as a gas leakage free mechanism and minimized compact size for a LPG cylinder.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.2
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• pp.111-118
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• 2013

Purpose of present study is to investigate the effects of thread pitch in coronal portion in scalloped implant with 2 different connections on loading stress using 3 dimensional finite element analysis. Scalloped implant with 4 different thread pitches (0.4mm, 0.5mm, 0.6, and 0.7mm) in the coronal part was modeled with 2 different implant-abutment connections. Platform matching connection had the same implant and abutment diameter so that they were in flush contact at the periphery while platform mismatching connection had smaller abutment diameter than implant so that their connection was made away from periphery of implant-bone interface. Occlusal loading of 100N force was applied vertically and 30 degree obliquely to all 8 models and the maximum von Mises bone stress was identified. Loading stress as highly concentrated in cortical bone. Platform mismatching scalloped implant with small thread pitch (0.4mm) model had consistently lowest maximum von Mises bone stress in vertical and oblique loads. Platform matching model had lowest maximum von Mises bone stress with 0.6mm thread pitch in vertical load and with 0.4mm thread pitch in oblique load. Platform mismatching connection had important roles in reducing maximum von Mises bone stress. Scalloped implant with smaller coronal thread pitch showed trend of reducing maximum von Mises bone stress under load.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.5
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• pp.81-87
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• 2015

In this paper, the finite element method was used for the flow and strength analysis of aluminum alloy under friction stir welding. The simulations were carried out using Sysweld s/w, and the modeling of the sheet was executed using Unigraphics NX6 s/w. The welding variables for the analysis were the shoulder diameter, rotating speed, and welding speed of the tool. Additionally, a three-way factorial design method was applied to confirm the effect of the welding variables on the flow and strength analysis with variance analysis. From these results, the rotating speed had the greatest influence on the maximum temperature, and the maximum temperature was $578.84{\pm}12.72$ at a confidence interval of 99%. The greater the rotating speed and shoulder diameter, the greater the difference between maximum and minimum temperature. Furthermore, the shoulder diameter had the largest influence on von Mises stress, and the von Mises stress was $184.54{\pm}12.62$ at a confidence interval of 99%. In addition to the increased shoulder diameter, welding speed, and rotating speed of the tool increased the von Mises stress.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.263-265
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• 2015

In this paper, a coil spring of the suspension components of the car is calculated through FEM(Finite Element Method) when a portion of the one is applied by an external load. we analyze the situation by using 'Large Deformation Analysis SW' in the EDISON structural dynamics server. Results of the analysis are about a displacement of the upper spring after deformation and total mass, and we use them to calculate the spring constant and maximum von-Mises stress by using Hooke's law and von-Mises stress equation. Finally, we visualize the relationship between the calculated spring constant and the mass through graphs and this data are beneficial for industries related to the spring.

• Journal of the Korean Institute of Gas
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• v.20 no.2
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• pp.43-48
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• 2016

This paper presents the finite element analysis results for bearing loads and stress distributions of safety helmets with an extruded structure. Five different analysis models with given same displacement load of 9.4mm have been analyzed for bearing loads and maximum von Mises stress. In these models, model 4 and model 5 are recommended as a maximum bearing load and low maximum stress for given displacement load of 9.4mm.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.4
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• pp.297-305
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• 2018

Purpose: This study aimed to analyze stress distribution and maximum von Mises stress generated in intracoronal restorations and in tooth structures of mandibular molars with various types of cavity designs and materials. Materials and Methods: Three-dimensional solid models of mandible molar such as O inlay cavity with composite and gold (OR-C, OG-C), MO inlay cavity with composite and gold (MR-C, MG-C), and minimal invasive cavity on occlusal and proximal surfaces (OR-M, MR-M) were designed. To simulate masticatory force, static axial load with total force of 200 N was applied on the tooth at 10 occlusal contact points. A finite element analysis was performed to predict stress distribution generated by occlusal loading. Results: Restorations with minimal cavity design generated significantly lower values of von Mises stress (OR-M model: 26.8 MPa; MR-M model: 72.7 MPa) compared to those with conventional cavity design (341.9 MPa to 397.2 MPa). In tooth structure, magnitudes of maximum von Mises stresses were similar among models with conventional design (372.8 - 412.9 MPa) and models with minimal cavity design (361.1 - 384.4 MPa). Conclusion: Minimal invasive models generated smaller maximum von Mises stresses within restorations. Within the enamel, similar maximum von Mises stresses were observed for models with minimal cavity design and those with conventional design.

• Journal of the Korean Institute of Gas
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• v.22 no.2
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• pp.72-77
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• 2018

This paper presents the FEM analysis results on the strength safety of LPG fuelling nozzle, which is composed of ball valve and long cylinder tube. For the strength safety analysis of LPG fuelling Nozzle, the gas pressure of 0.5~3.5MPa has been supplied to the ball valve and long cylinder tube bodies with the wall thickness of 1.7~3.5mm. The maximum von Mises stress of the ball valve with 1.7mm wall thickness is 25.4MPa for the supply gas pressure of 3.5MPa, which is 25.9% compared with that of the yield stress of the brass. And the maximum von Mises stress was 23.7MPa when a 3.5MPa gas pressure was applied to a long cylinder tube with a wall thickness of 1.7mm, which was 6.7% more safe than the ball valve which was analyzed under the same conditions. For the increased wall thickness, 2.0mm of the long cylinder tube, the maximum von Mises stress of 20.2MPa is 14.8% more safe compared with that of 1.7mm wall thickness of the same cylinder tube. Thus, the wall thickness of the ball valve and cylinder tube is recommended as an optimized thickness of 1.7~2.0mm for the strength safety of the LPG fuelling nozzle.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.22 no.1
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• pp.7-22
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• 1992

The stress distributions on a human mandible for 18 load cases under two different boundary conditions (mouth open and closed), using the three dimensional finite element modeling were studied. Also, the expected fracture loads for each load cases were calculated by using the Von-Mises yield criterion. The model of a mandible with all teeth was composed of 2402 hexahedron elements and 3698 nodes. CAD techniques were used to analyze the 3-dimensional results. The conclusions of this study were as follows: 1. In the mouth open state, the maximum stress occured at the condyle neck; when the lateral load was exerted, the maximum stress occured at the load side condyle. 2. In the mouth closed state, when the loads were exerted on the mandibular body and chin, the maximum stress occured at the loaded area, and when the loads were exerted on the angle and ramus, the maximum stress occured at the condyle neck. 3. The expected fracture loads in each load case were calculated using the Von-Mises yield criterion, and it was confirmed that the mandible in the mouth open state was more easily fractured than that in the mouth closed state, and the expected fracture loads are lesser in the cases that load direction is parallel at mandibular plane than 45°. 4. The magnitudes of the expected fracture loads increased in the order of angle, ramus, body and chin in case of the mouth closed state, while chin, body, angle and ramus in case of the mouth open state. 5. The Von-Mises stress concentration regions analyzed by F.E.M. corresponded well with the results of clinical studies.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.3
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• pp.222-228
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• 2011

Purpose: The purposes of this study were to evaluate the stress distributions and the displacements of obturator for edentulous maxillectomy patients and to compare them with those of complete denture using three-dimensional finite element analysis. Materials and methods: Based on the CT image of edentulous patient, three-dimensional finite element model of edentulous maxillae was constructed. Three-dimensional finite element model of edentulous maxillae with palatal defect was also fabricated. On each model, complete denture and obturator prosthesis were created. Vertical static force of 200 N was applied on the left maxillary premolar and molar region. The von Mises stress values and the displacements of models were analyzed using three-dimensional finite element analysis. Results: Maximum von Mises stress values were recorded in the cortical bones of both models. The von Mises stress value in the complete denture model was 2.73 MPa and 2.69 MPa in the obturator model. High von Mises stress values were also observed on the tissue surface of prosthesis. The maximum value of the displacement in the obturator was higher than that of complete denture. Conclusion: The obturator showed a worse result in terms of stress distribution and displacement than complete denture. In the prosthodontic rehabilitation of edentulous maxillectomy patient accurate impression procedure based on patients'anatomy and application of prosthodontic principle should be considered.

• Journal of the Semiconductor & Display Technology
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• v.16 no.4
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• pp.68-74
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• 2017

Nanoimprint lithography (NIL) is a next generation technology for fabrication of micrometer and nanometer scale patterns. There have been considerable attentions on NIL due to its potential abilities that enable cost-effective and high-throughput nanofabrication to the display device and semiconductor industry. Up to now there have been a lot of researches on thermal NIL, but most of them have been focused on polymer deformation in the molding process and there are very few studies on the cooling and demolding process. In this paper a cooling process of the polymer resist in thermal NIL is analyzed with finite element method. The modeling of cooling process for mold, polymer resist and substrate is developed. And the cooling process is numerically investigated with the effects of imprinting temperature and residual layer thickness of polymer resist on stress distribution of the polymer resist. The results show that the lower imprinting temperature, the higher the maximum von Mises stress and that the thicker the residual layer, the greater maximum von Mises stress.