• Elastomers and Composites
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• v.30 no.3
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• pp.235-246
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• 1995

When an O-ring is installed in a high fluid pressure device, a section of the O-ring is extruded into the piston-cylinder clearance gap. Any tendency towards extrusion will induce wear in dynamic applications, leading to premature failure of the seal. In this study, the mechanism of initial extrusion of the O-ring was studied, 1.e., how much amount of the O-ring will be extruded into the clearance gap at a certain pressure. The relationship between extrusion depth and a clearance gap or fluid pressure were studied by finite element analysis (FEA). After that, Salita's experimental data were analyzed. The result is that Initial extrusion depth for an O-ring into a clearance gap was 1.11 times the product of dimensionless pressure difference $(p-p_1)/E$ and clearance gap c. The required pressure $p_1$ for zero extrusion depth was found to decrease logarithmically with increasing clearance gap.

• Restorative Dentistry and Endodontics
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• v.29 no.5
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• pp.439-445
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• 2004

The purpose of this study was to evaluate the influence of plugger penetration depth on the apical extrusion of root canal sealer during root canal obturation with Continuous Wave of Condensation Technique. Root canals of forty extracted human teeth were divided into four groups and were prepared up to size 40 of 0.06 taper with ProFile. After drying. canals of three groups were filled with Continuous Wave of Condensation Technique with System $B^{TM}$ and different plugger penetration depths of 3. 5, and 7 mm from the apex. Canals of one group were filled with cold lateral compaction technique as a control. Canals were filled with non-standardized master gutta-percha cones and 0.02 mL of Sealapex. Apical extruded sealer was collected in a container and weighed. Data was analyzed with one-way ANOVA and Duncan's Multiple Range Test. 3 and 5 mm penetration depth groups in Continuous Wave of Condensation Technique showed significantly more extrusion of root canal sealer than 7 mm penetration depth group (p < 0.05). However, there was no significant difference between 7 mm depth group in Continuous Wave of Condensation Technique and cold lateral compaction group (p < 0.05). The result of this study demonstrates that deeper plugger penetration depth causes more extrusion of root canal sealer in root canal obturation by Continuous Wave of Condensation Technique. Therefore, special caution is needed when plugger penetration is deeper in the canal in Continuous Wave of Condensation Technique to minimize the amount of sealer extrusion beyond apex.

• Journal of the Korean Society of Safety
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• v.22 no.6
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• pp.27-34
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• 2007

Static or dynamic elastomeric O-ring seals are installed between joining parts, and play key roles of high pressure-tightening. Sealing performance and structural safety of the O-ring are dependent on groove design, plain diameter, squeeze and applications such as pressure and temperature. In this study, to solve O-ring problem squeezed and highly pressurized under laterally one-sided constrained condition, hyperelastic FE analyses are performed, and FE results are compared with measured ones by computer-aided tomography, deformed shape and extrusion depth of the O-ring. Through the comparisons, FE analysis technique was verified. In order to evaluate design sensitivity, Taguchi method was used to select FE analysis cases. Adjustment parameters are clearance gap, groove comer radius, plain diameter and squeeze. By means of verified FE analysis technique, it has been analysed how the parameters have effects on contact stress fields, internal stress fields, and extrusion depths. Sealing performance has been evaluated based on contact stress fields and contact widths, and structural safety on internal stress and strain, extrusion lengths.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.03b
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• pp.130-137
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• 1996

Several cold extrusion processes to produce an axisymmetric steel piston-pin are investigated for comparing each other. Two methods among four conventinal ones are selected to be simulated using the rigid-plastic finite element method. One of the both methods using a mechanical press has one stage process and the other utilizing a cold header applies a multi-stage process to produce a final product. Because the main process is a backward extrusion, the design criteria such as the backward extrusion ration and punch diameter to depth rationare ocnsidered. FEM analysis is performed mainly for strain distributin and load-stroke relationshis. Based on the results of preliminary simulatin, both process sequences are proved to have proper charicteristics suitable for each production method in terms of maximum load. Those simulation results will be a good design criteria in the future work to advance the manufacturing process.

• Restorative Dentistry and Endodontics
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• v.43 no.1
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• pp.2.1-2.10
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• 2018

Objectives: To determine the effect of size and insertion depth of irrigation needle on the amount of apical extruded debris and the amount of penetration depth of sealer using a confocal laser scanning microscope (CLSM). Materials and Methods: Twenty maxillary premolars were assigned to 2 groups (n = 10), according to the size of needle tip, 28 G or 30 G. Buccal roots of samples were irrigated with respective needle type inserted 1 mm short of the working length (WL), while palatal roots were irrigated with respective needle type inserted 3 mm short of the WL. Prepared teeth were removed from the pre-weighed Eppendorf tubes. Canals were filled with F3 gutta-percha cone and rhodamine B dye-labeled AH 26 sealer. Teeth were transversally sectioned at 1 and 3 mm levels from the apex and observed under a CLSM. Eppendorf tubes were incubated to evaporate the irrigant and were weighed again. The difference between pre- and post-weights was calculated, and statistical evaluation was performed. Results: Inserting needles closer to the apex and using needles with wider diameters were associated with significantly more debris extrusion (p < 0.05). The position of needles and level of sections had statistically significant effects on sealer penetration depth (p < 0.05 for both). Conclusions: Following preparation, inserting narrower needles compatible with the final apical diameter of the prepared root canal at 3 mm short of WL during final irrigation might prevent debris extrusion and improve sealer penetration in the apical third.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.356-363
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• 2001

Piston seal is a device designed to prevent leakage in split connecctions or between relatively moving part. Contact force, critical pressure at which extrusion occurs, leakage rate, fluid film thickness and friction force have been analyzed for some design parameter such as clearance between cylinder wall piston, depth of rectangular groove and pressure of sealed hydraulic fluid. In this paper, we analyze displacement and stress of Wearing by finite element analysis to understand Contact Behaviour Characters.

• Journal of Korea Multimedia Society
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• v.16 no.9
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• pp.1109-1118
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• 2013

Recently, stereoscopic three-dimensional(S3D) movie and video are becoming globally popular. However, there are some people who could not perceive 3D depth information well. Traditional stereopsia test tools could not analyze the subject's perceived depth accurately. Therefore, it is necessary to have a test tool that accurately measures the degree of perceived depth of subjects. In this paper, we suggested a 3D content depth measuring instrument and produced suitable 3D contents for the instrument. We measured subjects' perceived depth of 3D foreground objects in terms of $+1^{\circ}$, $-1^{\circ}$, $-2^{\circ}$ binocular disparity and compared the measured values with the theoretical values. Measured values were slightly bigger than the theoretical values. Deviation between the measured values and theoretical values increased with extrusion distances.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.10a
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• pp.174-184
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• 1996

Two methods for cold extrusion processes to produce an axisymmetric steel gear blank are investigated for comparing each other. The "classical" forming method consisting of four operations is selected first to be simulated using the rigid-plastic finite element method and uses single-die presses. The other using a fully automated transfer headers can produce the final part without interannealing. The final products must be checked at the design criteria such as area reduction, the extrusion ratio and punch diameter to depth ratio, especially punch buckling by simulations. FEM analysis is performed mainly for strain distribution, both process sequences are proved to have proper charicteristics suitable for each production method in terms of maximum load. Those simulation results will provide good design criteria in the future work to advance the manufacturing process.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.980-985
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• 2008

Since its invention at TWI in 1991, Friction Stir Welding (FSW) has become a major joining process in the aerospace, railway and ship building industries especially in the fabrication of aluminium alloys. In an attempt to optimize the friction stir welding process of Al alloys for extrusion Aluminium carbody of HEMU-400X (Extrusion Aluminum 6xxx series), effects of joining parameters such as tool rotating speed, plunging depth and dwelling time on the weld joints properties were evaluated. Experimental tests were carried out for butt joined Al plates. A wide range of joining conditions could be applied to join Al alloys for Extrusion Aluminum 6xxx series without defects in the weld zone except for certain welding conditions with an insufficient heat input. The microstructures of welds have dynamic-recrystallized grain similar to stir zone in FSW weld. For sound joints without defects, at the rotation speed of 700 rpm with different welding speeds, the tensile strengths of the Stir Zone(SZ) were almost the same, 80% of those of the base metal. (JIS Z 2201)

• Proceedings of the KACD Conference
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• 2002.11a
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• pp.697-697
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• 2002

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