• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.143-148
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• 2018

3D printing has been expanding beyond the bio/nano field to the automobile and aviation industries. 3D-printing technology has to overcome real problems to have economic value compared to its unlimited usability. Typically, the difference in mechanical strength along the lamination direction requires sufficient research to ensure reliability. In this paper, we study the anisotropic properties of ABS based on the stacking method of FDM 3D printing. Specifically, the mechanical properties of ABS material are determined through a tensile test and 3-point bending test, and the in-plane orthotropic properties are ascertained.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.2
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• pp.119-123
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• 2014

In this study, four kinds of specimens of PE(polyethylene)-based insulating materials were prepared for selecting the optimum insulation materials in a wet environment. The specimens were tested by various methods, the anti tracking test, the transmittance test in the water vapor transmittance(WVT) and the abrasion resistive test, etc. The HDPE(high-density polyethylene) specimen was showed excellent property in the tracking resistance test and the lowest transmittance in water vapor transmittance test. In the abrasion resistive test, the LLDPE(linear low-density polyethylene) and MDPE(medium-density Polyethylene) were showed excellent mechanical properties. The value of cut-through resistance for MDPE and HDPE were superior to that for LLDPE and LDPE(low-density polyethylene).

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.11
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• pp.2676-2683
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• 1993

Plane strain punch stretching test(PSST) was performed for various automotive steel sheets. To clarify the effect of tensile properties on plane strain stretchability, the limiting punch height(LPH) values were obtained in plane strain punch stretching test and related to the tensile properties of the materials. The results show that the total elongation El and work hardening exponent n compared to other parameters obtained from tensile test well correlate with the LPH value. In comparision with the Erichsen test and LDH test the PSST can be statistically used as an alternative in assessing the stamping formability of automotive steel sheets with the advantages of good reproducibility and easy testing method.

• Journal of Korea Foundry Society
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• v.35 no.4
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• pp.88-98
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• 2015

The effects of quenching and tempering temperatures on the tensile, impact and corrosion properties of A487 alloy cast with different C contents of 0.16, 0.19 to 0.23 wt.% were examined. The impact tests were conducted at $25^{\circ}C$ and $-60^{\circ}C$ and the immersion test was performed using 3.5% NaCl solution for 14 days. The quenching temperature affected the mechanical properties of A487 alloy cast, while the magnitude of change varied depending on the C content. The increase in tempering temperature showed the typical trend of decreasing tensile strength and increasing impact properties. The change in quenching and tempering temperature in this study did not affect the corrosion properties of A487 alloy significantly. The change in mechanical and corrosion properties of A487 with different C contents was discussed based on the microstructural and fractographic observation.

• Journal of Korea Foundry Society
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• v.17 no.5
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• pp.494-501
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• 1997

In order to manufacture large rod preforms of 2014 Al alloy with a good mechanical property by spray forming method, it was spray-formed at a droplet temperature of $715^{\circ}C$, a droplet flight distance of 400mm, and a spraying angle of $35^{\circ}$. The rod preforms were extruded at $397^{\circ}C$ with the die temperature of $420^{\circ}C$ under the hot extrusion ratio 21:1 and T6 heat treatment was performed. The 2014 Al alloys cast by hot top process were also extruded and heat-treated at the same condition as a reference material. Microstructural observation and tensile test were carried out to investigate the effects of extrusion on microstructure and mechanical property of spray-formed Al alloy. Spray-formed Al alloys had many porosities due to inappropriate process conditions such as long droplet flight distance and low droplet temperature but have fine equiaxed grain. These porosities were reduced with decreasing in grain size by hot extrusion. Ultimate tensile strength and yield strength of spray formed-extruded 2014 Al alloy were inferior to those of the normal cast-extruded 2014 Al alloy, but elongations were superior. The control of porosity was important to get spray formed preform with a good mechanical property.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.48-53
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• 2006

A methodology is described for predicting the fatigue life of the resistance spot weldment including strain rate effect. Because it is difficult to perform a physical failure test with high strain rate, an analytical method is necessary to get the mechanical properties of various strain rate, To this end, quasi-static tensile-shear tests at several strain rate were performed on spot weldments of SPC. These test provided the empirical data with the strain rate. With these results, we formulated the function of fatigue life prediction using the lethargy coefficient which is the global material property from tensile test. And, we predicted the fatigue life of spot weldment at dynamic strain rate. To confirm this method for fatigue life prediction, analytical results were compared with the experimental fatigue data.

• Journal of Powder Materials
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• v.19 no.6
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• pp.416-423
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• 2012

This paper introduces an effect of a preparing $ZrO_2$-Ag composite on its mechanical properties and microstructure. In present study, $ZrO_2$-Ag was prepared by reduction-deposition route and wetting dispersive milling method, respectively. Two type of Ag powders (nano Ag and micron Ag size, respectively) were dispersed into $ZrO_2$ powder during wetting dispersive milling in D.I. water. Each sample was sintered at $1450^{\circ}C$ for 2hr in atmosphere, and then several mechanical tests and analysis of microstructure were carried out by bending test, hardness, fracture toughness and fracture surface microstructure. As for microstructure, the Ag coated $ZrO_2$ showed homogeneously dispersed Ag in $ZrO_2$ in where pore defect did not appear. However, $ZrO_2$-nano Ag and $ZrO_2$-micro Ag composite appeared Ag aggregation and its pore defect, which carried out low mechanical property and wide error function value.

• Korean Journal of Food Science and Technology
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• v.16 no.2
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• pp.175-178
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• 1984

The effects of the addition of starch, salt and soda ash to the dough for Naengmyon (wheat-sweet potato starch) on the mechanical property of Naengmyon noodle were evaluated by using creep test. The strain measurement was made by taking photograph with VTR system. The creep curve of noodle strand could be fitted to the 4 element Burgers model. The instantaneous elasticity and Newtonian viscosity of the noodle strand decreased by the addition of starch. The instantaneous elasticity decreased by the addition of salt up to 4%. The mechamical parameters of the noodle varied inconsistently by the addition of soda ash.

• Korean Journal of Metals and Materials
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• v.49 no.2
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• pp.145-152
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• 2011

Mechanical and property corrosion resistance of Mg-Zn-Y alloys with an atomic ratio of Zn/Y of 6.8 are investigated using optical microscopy, scanning electron microscopy, transmission electron microscopy, uniaxial tensile test and corrosion test with immersion and dynamic potentiometric tests. The alloys showed an in-situ composite microstructure consisting of ${\alpha}$-Mg and icosahedral phase (I-phase) as a strengthening phase. As the volume fraction of the I-phase increases, the yield and tensile strengths of the alloys increase while maintaining large elongation (26~30%), indicating that I-phase is effective for strengthening and forms a stable interface with surrounding ${\alpha}$-Mg matrix. The presence of I-phase having higher corrosion potential than ${\alpha}$-Mg, decreased the corrosion rate of the cast alloy up to I-phase volume fraction of 3.7%. However further increase in the volume fraction of the I-phase deteriorates the corrosion resistance due to enhanced internal galvanic corrosion cell between ${\alpha}$-Mg and I-phase.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.17 no.2
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• pp.109-118
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• 2021

In the periodic surveillance material test for the spacer component of fuel channel assembly in CANDU, a microstructural characterization analysis is required in addition to the mechanical property evaluation test. In this study, detailed microstructure analysis and simple mechanical property evaluation of archive spacer parts were conducted to indirectly support the surveillance test and assist in the study of spacer material degradation. We investigated the microstructural characteristics of the spacer garter spring coil through comparative analysis with the plate material. The main microstructure characteristics of the garter spring coil X-750 are represented by the fine grain size distribution, the ordering phase distribution developed inside the matrix, the high dislocation density inside the grains, and the arrangement of coarse carbides. In addition, the yield strength of the garter spring coil X-750 was indirectly evaluated to be approximately 1 GPa. We also established an analytical method to elucidate the microstructural evolution of the radioactive spacer garter spring coil X-750 based on Canadian research experiences. Finally, we confirmed the measurement technique for helium bubble formation through TEM examination on the helium implanted X-750 material.