• Journal of Korea Foundry Society
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• v.28 no.4
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• pp.170-174
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• 2008

Mechanical properties of high strength ductile cast iron for the brake caliper of truck were investigated. Meanwhile the nodularity and nodule count decreased respectively from 92 and 95 to 80% and $60/mm^2$ with increased thickness, the volume fractions of graphite, pearlite and ferrite didn't change much and were in the ranges of 12.0-13.5, 52.6-55.0 and 33.0-35.2, respectively. Hardness, tensile strength and elongation in the mechanical properties of the castings of brake caliper were BHN 241, 710 MPa and 9.5%, respectively.

• Journal of the Korean Society for Heat Treatment
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• v.7 no.4
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• pp.298-306
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• 1994

This study was performed to investigation the effect of austempering temperature on the mecanical properties and fracture Characteristic of the ductile cast iron with contains Cu and Mo. The obtained results of this study were as follows; Microstructure of austemped ductile cast iron obtained by austempering were low bainite with some martensite at $250^{\circ}C$, mixture of low and upper bainite at $300^{\circ}C$ and upper bainite at $350^{\circ}C$. With increasing austempering temperature, yield strength, tensile strength and hardness decreased, while the elongation and impact absorption energy increased. With increasing austempering temperature, fracture toughness value increased and mainly controlled by bolume fraction of retained austenite. The volume fraction of retained austenite increased and the fracture surface obtained fibrous and dimple with increasing austempering temperature.

• Journal of the Korean Society for Heat Treatment
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• v.30 no.3
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• pp.99-105
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• 2017

This study was carried out to investigate the effect of heat treatment on the microstructure and mechanical properties in 90% hot forged Incoloy 825 alloy. With increasing solution treatment temperature, the grain size increased and the volume fraction of total precipitates decreased, and the precipitates disappeared at $1,000^{\circ}C$. With increasing aging time at $700^{\circ}C$, the volume fraction of precipitate increased and the precipitates size increased. Most of the precipitates consist $Cr_{23}C_6$ carbide, and a small amount of TiC carbide was also observed. With decreasing solution treatment temperature and increasing aging time, tensile strength and hardness increased, and the elongation and impact value decreased. With increasing aging time, the impact value decreased sharply by the increased of the precipitate size.

• Earthquakes and Structures
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• v.6 no.2
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• pp.127-140
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• 2014

Laminated rubber bearing is very popular base isolation of earthquake engineering pertaining to the passive structural vibration control technologies. Rubber used in fabricating NRB and LRB can be easily attacked by various environmental factors such as oxygen, heat, light, dynamic strain, and organic liquids. Among these factors, this study carried out thermal aging test to investigate the effect of thermal aging on the mechanical properties of laminated rubber bearings in accelerated exposure condition of $70^{\circ}C$ temperature for 168 hours. The compressive-shear test was carried out to identify the variation of compressive and shear properties of the rubber bearings before and after thermal aging. In contrast to tensile strength and elongation tests, the hardness of rubber materials showed the increasing tendency dependent on exposure temperature and period. Based on the test results, the property changes of rubber bearing mainly aged by heat are quantitatively presented.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2368-2373
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• 1994

The advancement of the mechanical properties of metal materials caused by a recent high technology contributes to the stability and productivity of mechanical structures. However, the advanced mechanical properties depends on the conditions of crystal boundaries and the improvement of the texture. Although the tensile strength and a hardness of a steel would be increased by the adding B, it seems to be a marked decreases of the toughness which caused in the weaken workability. This study is concerned with a characteristics of the B compound which will be mixed with $H_3BO_3$ and the metallic magnesium. What affected in the mechanical property and texture is checked by the strength and the texture test. As a result, it is shown that the improvement of the mechanical property and the texture homogeneity. In addition, it seems that a molten metal which is added by the B compound is deoxized and cleansed.

• Journal of Korea Foundry Society
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• v.32 no.2
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• pp.81-85
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• 2012

The effects of section size and melt holding time on the mechanical properties and microstructure of high silicon ductile cast iron were investigated. The strength, elongation and hardness of the test specimen with smaller cross-section were higher than those with larger one. The nodule count and volume fraction of pearlite of the former were higher than those of the latter. The mechanical properties decreased with increased melt holding time before pouring. Nodularity and nodule count decreased and the volume fraction of pearlite rather slightly increased with it.

• Elastomers and Composites
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• v.17 no.1
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• pp.13-21
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• 1982

The purpose of this dissertation is to compare bound andtioxidant, MHPPD with the ordinary one, IPPD, when high polymers are used like NR and SBR. The effect of rubber bound antioxidant and ordinary antioxidant on the Mooney scorch time has been studied by means of the Mooney viscometer. The ageing properties of vulcanizates containing rubber-bound antioxidant and ordinary antioxidant have been studied in terms of hardness, tensile strength and elongation. The results of the Mooney scorch time and ageing properties are as follows: When MHPPD was mixed with NR or SBR compounds, the Mooney scorch time was faster than the IPPD compounds. Also the ageing properties of the vulcanizates containing MHPPD were much superior to the IPPD compounds. Furthermore, the vulcanizates comporised of MHPPD have taken andvantage of and resistance in the ozone test.

• Elastomers and Composites
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• v.53 no.3
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• pp.168-174
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• 2018

Natural rubber (NR) and bromo-isobutylene-isoprene rubber (BIIR) were compounded with other formulation chemicals through polymer blending via a mechanical mixing method. After rubber vulcanization by hot-press compression molding, the cure characteristics, mechanical properties, and ozone resistance of the NR/BIIR blends were measured. As the BIIR content increased, the maximum torque of the blends decreased, while the optimum cure time and scorch time tended to increase. Furthermore, the hardness of the blends increased with increasing BIIR content, reaching the maximum value at 75 wt% BIIR, and decreased with a further increase in the BIIR loading. The tensile strength and elongation at break decreased with an increase in the BIIR content, reaching the minimum value at 75 wt% BIIR, and increased with a further increase in the BIIR content. In the ozone resistance test, cracks were not generated when the BIIR content was more than 75 wt%.

• Journal of Aerospace System Engineering
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• v.7 no.4
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• pp.36-41
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• 2013

In order to improve incombustibility of EPDM(Ethylene propylene diene monomer)-based rubber, inorganic materials as $Al(OH)_3$ and $Sb_2O_3$ were added. The mechanical and thermal properties have been measured for vulcanized rubber loaded with different concentrations of $Al(OH)_3$ and $Sb_2O_3$. As inorganic material contents increases from 5phr to 30phr, the specific gravity and hardness increase while elongation at break decreases. This study performed incombustibility test and thermal analysis through TGA(Thermogravimetric Analyzer). As a results, incombustible and thermal properties of EPDM-based rubber were improved as $Al(OH)_3$ and $Sb_2O_3$ contents increase.

• Corrosion Science and Technology
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• v.12 no.5
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• pp.245-252
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• 2013

In this study, mechanical and electrochemical characteristics with welding material in MIG welded with ROBOT for dissimilar Al alloys were investigated using various experiment methods. The MIG welding by ROBOT with ER5183 and ER5556 for the 5456-H116 and 6061-T6 Al alloy were carried out. The hardness of welding zone was lower than that of base metal. In electrochemical experiment, ER5183 welding material presented excellent characteristics. The yield strength and maximum tensile strength in welding with welding material of ER5183 presented lower value than those of ER5556. The elongation and time-to-fracture showed the opposite results.