• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2001.11a
• /
• pp.350-355
• /
• 2001

Minimum clearance between the piston seal groove of a piston and cylinder bore to ensure against extrusion of the piston seal and leakage of working fluids is an important design parameter for a seal designer in hydraulic cylinder application. 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 ACGT seal by finite element analysis to understand Contact Behaviour Characters

• Asian-Australasian Journal of Animal Sciences
• /
• v.15 no.1
• /
• pp.102-105
• /
• 2002

Seventy-two crossbred pigs weighing an average of 41.5 kg were assigned on the basis of sex, weight and litter to one of four dietary treatments in a factorial (4 treatments${\times}$2 sexes) arrangement. The control diet was based on barley and soybean meal while the experimental treatments consisted of diets in which a portion of the dietary protein was supplied by 20% of a 50:50 blend of extruded ($130^{\circ}C$ for 20 to 25 sec) peas and full-fat canola seed, 20% of a 50:50 blend of unextruded peas and full-fat canola seed or a diet containing 10% peas, 6% canola meal and 4% canola oil (to equal the level of canola oil provided by 10% whole canola seed). Digestibility coefficients for dry matter, crude protein and gross energy were significantly higher (p<0.05) for the control diet than for the other three diets. Extrusion produced no beneficial effects (p>0.05) on nutrient digestibility and there were no differences in digestibility between the diet based on intact canola seed compared with the diet containing canola meal and oil. Choice of protein supplement had no significant effects on gain, feed intake or feed conversion during the grower or finisher phases and over the entire experimental period. Extrusion of the pea-canola blend produced no beneficial effects on pig performance as the performance of pigs fed either the extruded or unextruded blend of peas and canola seed was similar. In addition, the performance of pigs fed diets containing intact canola seed was similar to that of pigs fed canola meal and oil. Castrates gained faster and consumed more feed than gilts (p<0.05). However, their feed conversion was poorer than that of the gilts during the finisher period. There were no significant differences in carcass traits between pigs fed the control and any of the experimental treatments. Extrusion had no effect on carcass traits and the carcasses of pigs fed canola meal and oil did not differ from those of pigs fed whole canola seed. Castrates had a significantly lower dressing percentage, lower estimated lean yield but greater loin fat depth than gilts (p<0.05). The results of this experiment indicate that peas in combination with canola seed or canola meal are an acceptable alternative to soybean meal as a protein supplement for use in growing-finishing swine diets. Extrusion did not appear to have any beneficial effects on the nutritional value of the canola seed-pea blend as nutrient digestibility, growth performance and carcass traits were similar for pigs fed the unextruded blend of peas and canola seed compared with the extruded product. Since the process adds to the cost of the raw products, its use is unlikely to be economical.

• Transactions of Materials Processing
• /
• v.22 no.8
• /
• pp.437-441
• /
• 2013

Recently, the engraving of letters or a pattern on a product surface has received more attention especially in trying to satisfy the customer requirements. Half-piecing is a protrusion forming process that pierces only 40~50% of the material thickness. In the current study, the half-piercing technique for making clear letters by protruding sheet material was selected and studied. The influence of clearance and penetration depth was investigated by measuring the camber and extruded length of a protrusion after experiments. In addition, a numerical analysis was performed for the same working conditions and compared with experimental results. It is shown that, as the clearance increases, the camber of a protrusion increases rapidly and the extruded length decreases slightly. The deformation pattern around the cutting edge during half-piercing changes from an extrusion mode to a shearing mode as the clearance changes from minus to plus values. It is also confirmed that the experimental results show a good agreement with the numerical analyses.

• Proceedings of the KSR Conference
• /
• 2004.10a
• /
• pp.704-709
• /
• 2004

The wear behavior and the mechanical property of Cu-$TiB_2$ composites were examined. Cu-$TiB_2$ composites were fabricated by hot extrusion and cold drawing with $TiB_2$ contents(1$\∼$5vol.$\%$) and the size of $TiB_2$ particles(10$\mu$m and 20$\mu$m). The pin-an-disk wear test was carried out under dry sliding wear conditions which loads varied with from 20N to 100N. At the time, counterpart wear material used SM45C. The experimental results showed that the friction coefficient and wear rate decreased with increasing the $TiB_2$ contents and decreasing the size of $TiB_2$ particle. Also, the depth of plastically deformed zone decreased with increasing the $TiB_2$ contents and decreasing the size of $TiB_2$ particle.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.05a
• /
• pp.78-81
• /
• 2005

The aluminum Subframe for automobile was developed using hybrid process, i.e. extruforming and press forming. To achieve a $30\%$ weight reduction compared with convensional steel subframe keeping satisfactory performance, the design of cross-section of extrusion part was initiated, then forming simulation was performed and the final design was determined. In addition, we tried to estibilish proper aluminum welding conditions for good penetration depth and few pore defact, finally the prototype of aluminum subframe was assembled using MIG welding method.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.28 no.1
• /
• pp.1-8
• /
• 2008

The object of this study is to develop the examination technique for measuring the O-ring deformation behavior under the pressure and the squeezed condition simultaneously. The O-ring deformation measuring device in which two grooves were dug to insert the two O-rings was manufactured to be not deformed under the high pressure and the 1 mm and 0.1 mm gap were designed to measure the extrusion lengths under the internal pressure. The beam hardening correction, the histogram analysis and the dead zone correction were executed to exactly measure the shape of O-ring deformation and the lengths of the O-ring deformation were measured by the LSF and the ERF. The computed tomography applied the pressure of 0, 1.378, 4.902, 9.804, 15.692 MPa at 22.3% squeezed condition and the expanded diameter, contact length and extrusion depth were measured in each pressure. The shape of O-ring deformation was evaluated by the FEM to verify the results of measuring by the computed tomography and the area of O-ring was mutually compared to the area measured by the computed tomography.

• Journal of Powder Materials
• /
• v.13 no.6 s.59
• /
• pp.421-426
• /
• 2006

The microstructural and mechanical properties of Al-Si alloyed powder, prepared by gas atomization fallowed by hot extrusion, were studied by optical and scanning electron microscopies, hardness and wear testing. The gas atomized Al-Si alloy powder exhibited uniformly dispersed Si particles with particle size ranging from 5 to $8{\mu}m$. The hot extruded Al-Si alloy shows the average Si particle size of less than $1{\mu}m$. After heat-treatment, the average particle size was increased from 2 to $5{\mu}m$. Also, mechanical properties of extruded Al-Si alloy powder were analyzed before and after heat-treatment. As expected from the microstructural analysis, the heat-treated samples resulted in a decrease in the hardness and wear resistance due to Si particle growth. The friction coefficient of heat-treated Al-Si alloyed powder showed higher value tough all sliding speed. This behavior would be due to abrasive wear mechanism. As sliding speed increases, friction coefficient and depth and width of wear track increase. No significant changes occurred in the wear track shape with increased sliding speed.

• Computers and Concrete
• /
• v.14 no.3
• /
• pp.211-231
• /
• 2014

Prestressed hollow-core slabs (HCS) are widely used for modern lightweight precast floor structures because they are cost-efficient by reducing materials, and have excellent flexural strength and stiffness by using prestressing tendons, compared to reinforced concrete (RC) floor system. According to the recently revised ACI318-08, the web-shear capacity of HCS members exceeding 315 mm in depth without the minimum shear reinforcement should be reduced by half. It is, however, difficult to provide shear reinforcement in HCS members produced by the extrusion method due to their unique concrete casting methods, and thus, their shear design is significantly affected by the minimum shear reinforcement provision in ACI318-08. In this study, a large number of shear test data on HCS members has been collected and analyzed to examine their web-shear capacity with consideration on the minimum shear reinforcement requirement in ACI318-08. The analysis results indicates that the minimum shear reinforcement requirement for deep HCS members are too severe, and that the web-shear strength equation in ACI318-08 does not provide good estimation of shear strengths for HCS members. Thus, in this paper, a rational web-shear strength equation for HCS members was derived in a simple manner, which provides a consistent margin of safety on shear strength for the HCS members up to 500 mm deep. More shear test data would be required to apply the proposed shear strength equation for the HCS members over 500 mm in depth though.

• The korean journal of orthodontics
• /
• v.44 no.2
• /
• pp.77-87
• /
• 2014

Objectives: This study was designed to define the Korean norm values for the Ricketts analysis. Methods: In this longitudinal study, lateral cephalograms of 31 subjects with normal occlusion were taken biennially from ages 9-19 years. Cephalometric measurements were performed. Parameters for which the 10-year change did not exceed one standard deviation were defined as unchanged. The means and standard deviations for the measured parameters were determined for each age group. Results: No significant changes in growth were observed in the molar relationship, incisor overjet, incisor overbite, mandibular incisor extrusion, interincisor angle, lower incisor tip (B1) to A point-Pogonion (A-PO) plane, upper incisor tip (A1) to A-PO plane, B1 inclination to A-PO, A1 inclination to A-PO, B1 inclination to Frankfurt plane (FH), convexity, lower facial height, facial axis, maxillary depth, maxillary height, palatal plane to FH, cranial deflection, ramus Xi position, or porion location. Continual changes over the 10 years of growth were observed in the maxillary first molar distal position to pterygoid true vertical plane, facial depth, mandibular plane to FH, anterior cranial length, mandibular arc, and corpus length. Conclusions: Clinicians can apply the Korean norms at age 9 as determined in this study when using the Ricketts analysis. The patient's age at the beginning of treatment and their sex should be taken into consideration when drawing visual treatment objectives.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.30 no.4
• /
• pp.654-659
• /
• 2003

Intrusive luxation that takes approximately three percent of permanent teeth commonly occures at anterior teeth. This intrusion frequently leads to pulp necrosis, root resorption, marginal bone loss and these complications are influenced by depth of intrusion and stage of root development. Various treatment approaches have been suggested to manage of intrusive luxation. Techniques aiming to reposition the intruded tooth include an observation for spontaneous re-eruption, surgical or orthodontic repositioning. We report two cases with clinically satisfactory results for traumatically intruded maxillary central incisor. In one case which has a large open apex and mild intrusion depth, we observed for spontaneous eruption and then repositioning by forced eruption method. In other case, which has been completely intruded, was repositioned by surgical extrusion and followed by apexification.