• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.8
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• pp.52-59
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• 2021

In this study, we experimentally evaluated the mechanical properties and geometric form accuracy in FDM 3D printing processes based on the printing direction, building direction, and layer thickness. The specimen test results showed that the tensile strength increased by over 33% in the printing direction compared to the direction perpendicular to printing and the tensile strength becomes larger as the layer thickness decreased. Furthermore, the tensile and impact strengths in the building direction were significantly reduced due to the difference in the interlayer joining and bonding strengths of the fused material. Additionally, shrinkage of the material due to phase change induced curl distortion especially in thin and long 3D-printed products, which increased as the layer thickness increased.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.1
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• pp.10-16
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• 2021

Exhaust manifold is a very important component that is directly connected to air environment pollution and that requires strict mechanical properties such as high temperature fatigue and oxidation. Among stainless steels, the ferritic stainless steel with body-centered cubic structure shows excellent resistance of stress-corrosion cracking, ferromagnetic at room temperature, very excellent cold workability and may not be enhanced by heat treatment. The microstructural characteristics of four cast ferritic stainless steels which are high heat-resistant materials, were analyzed. By comparing and evaluating the mechanical properties at room temperature and high temperature in a range of 400℃~800℃, a database was established to control and predict the required properties and the mechanical properties of the final product. The precipitates of cast ferritic stainless steels were analyzed and the high-temperature deformation characteristics were evaluated by comparative analysis of hardness and tensile characteristics of four steels at room temperature and from 400℃ to 800℃.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.469-472
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• 2008

As a general rule, concrete has higher compression strength than bending and toughness. but Ductile fiber reinforced cementitious composite has high toughness property owing to adding a large volume fiber. Therefore uniaxial tensile strength test is imperative to evaluate high toughness property of ductile fiber reinforced cementitious composite in comparison with general concrete test. but in testing compression strength, Result is different by factor of thickness, shape and edge condition. Uniaxial tensile strength test is affected by fiber's length and section area because of cementitious composite property and factor of fiber arrangement. This study evaluates toughness property of ductile fiber reinforced cementitious composite according to thickness and edge condition. The more thickness is thin, the more high performance by fiber arrangement

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.2
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• pp.213-221
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• 2009

This study provides the optimum papain treatment method and its effect on wool/polyester blend fabrics. The enzymatic treatment condition is optimized depending on its pH level, temperature, concentration of enzyme, treatment time and concentration of activators. The characteristics of samples treated with the papain are measured using weight loss, tensile strength, whiteness, WCA, dyeing property and surface micrographs. The results are described as follows: According to measuring weight loss, tensile strength and whiteness, a pH level of 7.5, $70^{\circ}C$, 10% papain(o.w.f.) and 60minutes of treatment time are optimized for papain treatment. L-cysteine and sodium sulfite are able to activate the papain. The optimum concentrations of them are 10mM and 50mM respectively. The WCA of fabrics is decreased since papain treatment makes wool/polyester blend fabrics more hydrophilic. Scouring with papain treatment improves whiteness and dyeing property of fabrics. The dyeing property of papain-treated fabrics is enhanced simply by a single step dyeing process using a basic dye. The surface of wool treated with papain in the presence of L-cysteine shows to be descaled. The surface of wool fibers in the presence of sodium sulfite, however, shows it is hydrolyzed evenly instead of being descaled. The surface of papain treated polyester fibers shows cracks and voids.

• Korean Journal of Materials Research
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• v.14 no.12
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• pp.863-869
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• 2004

The purpose of this research is to investigate the mechanical property and ductile-brittle transition temperature of Ti-Nb-P added extra low carbon interstitial free steel having a tensile strength of 440 MPa. The mechanical property and transition temperature of hot rolled steel sheets were more influenced by the coiling temperature rather than by the small amount of alloying element. Further, at the same composition, the property of the specimen coiled at low temperature was superior to that obtained at higher coiling temperature. The fracture surface of 0.005C-0.2Si-1.43Mn steel coiled at $630^{\circ}C$ showed a ductile fracture mode at $-100^{\circ}C$, but coiling at $670^{\circ}C$ showed a transgranular brittle fracture mode at $-90^{\circ}C$. The galvannealed 0.006C-0.07Si-1.33Mn steel sheet annealed at $810^{\circ}C$ has tensile strength and elongation of 442.8 MPa and $36.6\%$, respectively. The transition temperature of galvannealed 0.006C-0.07Si-1.33Mn steel sheet was increased with a drawing ratio, and the transition temperature of the galvannealed 0.006C-0.07Si-1.33Mn steel was $-60^{\circ}C$ at a drawing ratio of 1.8

• Fashion & Textile Research Journal
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• v.8 no.3
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• pp.357-362
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• 2006

This study is to evaluate the objective sensibility of the commercial lining fabrics. Five kinds of the linings were collected by adding taffetas with four kinds of fibers (polyester, nylon, rayon, and acetate) to one polyester stretch fabric. The six basic mechanical and hand properties were studied by using KES-FB system (Kawabata Evaluation System). The result of measuring the mechanical properties shows that polyester has high bending rigidity (B), that polyester-stretch has a high value of linearity of load-extension curve (LT), tensile energy (WT), tensile resilience (RT), and coefficient of friction (MIU) and a low value of bending rigidity(B), shear property, and geometrical roughness (SMD). The nylon has a high value of bending rigidity (B), shear property, and compression resilience (RC). The rayon has a high value of coefficient of friction (MIU) and linearity of compression-thickness curve (LC) and a low value of shear property, and the acetate has a low value of shear property. The result of hand value shows that polyester, nylon, and acetate are a high value of KOSHI (stiffness), NUMERI (smoothness), and FUKURAM (fullness & softness), and they feel stiff and massive, that rayon has a low value of NUMERI and FUKURAMI. The total result of hand value shows that polyester taffeta and polyester stretch fabric are about the same as the best material for the lining of a woman's dress for spring and summer, and the next thing is acetate, but nylon and rayon are somewhat inferior materials. This provides a fundamental data for the comfortable clothing production of a higher value-added product through the study on the mechanical and hand properties of the lining as well as the right side of fabrics.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.217-223
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• 2019

The application of 3D printing technology is expanding due to the production of the complex-shape parts and the one-step manufacturing process. Moreover, various technical solutions in 3D printing are emerging through continuous research and development. Representative technologies include SLS technology, in which a desired area is sintered and laminated by irradiating a powder-type material with a laser. In addition, high-performance engineering plastic parts are being manufactured in increasing numbers. In this study, tensile specimens were fabricated from polyamide 12, a widely available polymer, and the glass bead-reinforced polyamide 12. The specimen-build orientation was divided into 0°, 45°, and 90° on the fabrication platform, and the tensile test temperature was -25℃, 25℃, and 60℃. The test results showed that the tensile modulus of both materials decreases as the build orientation becomes closer to 90°. In addition, the tensile strength of glass bead-reinforced PA12 showed more dependence on the build orientation than PA12. In addition, the tensile modulus and tensile strength decreased with increasing test temperature.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.5
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• pp.1543-1551
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• 1996

The static tensile load bearing capability of as adhesively-bonded tubular single lap jint that is calculated usign the linear mechanical properties of adhesive is usually far from the experimentally determined because the majority of the load transfer of the adhesively-bonded jointd is accomplished by the nonlinear behavior of the rubber-toughened eoxy adhesive. In this paper, both the nonlinear mechanical properties and the fabrication residual thermal stresses of adhesive were included in the calculation of the stresses of adhesively-bonded joints. The onlinear tensile properties of adhesive were approximated by an exponential form which was represented by the initial tensile modulus and ultimate tensile stength of adhesive. The stress distribution in the adhesive were calculated by applying the load obtained from the tensile tests. From the tensile tests and the stress analysis of adhesively-bonded hoints, the failure model for adhesively-bonded tubular single lap joints was proposed.

• Applied Microscopy
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• v.39 no.1
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• pp.49-56
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• 2009

In this study, we investigated tensile properties and ultrastructural changes of straight permed hair using the rheometer and the scanning electron microscopy. First, we compared the morphological characteristic between the virgin hair and the straight permed hair after testing tensile strength. Cuticle cells were heavily lifted off in straight permed hair than in the virgin hair. Cuticle cells were separated by the destruction of intercellular membrane complex and no destruction or damage were found in cytoplasm. In the comparative test for tensile characteristic between the virgin hair and the straight permed hair, tensile distance of the straight permed hair was decreased by 24.5% or 3.05 mm than the virgin hair. The tensile strength was decreased by 34.63% or $5.62\;g/cm^2$ and the maximum stress by 34.59% or 56.12 g. As a result, the tensile property dropped to the lowest level with the straight permed hair than with the bleached hair or the permanent dyed hair of previous studies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.25-31
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• 2018

Selective Laser Melting is one of the representative 3D printing techniques for handling metal materials. The main factors influencing the characteristics of structures fabricated by the SLM method include the build-up angle of structures, laser power, laser scan speed, and scan spacing. In this study, the tensile properties of AlSi10Mg alloys were investigated by considering the build-up angle of tensile test specimens, laser scanning speed and scan spacing as variables. The yield stress, tensile strength, and elongation were considered as tensile properties. From the test results, it was confirmed that the yield stress values were lowered in the order of 0, 45, and 90 based on the manufacturing direction of the tensile specimen. The maximum yield stress value was obtained at 1870 mm / min based on the laser scan speed. The yield stress size decreased with decreasing scan speed. Based on the laser scan spacing, as the value increases, the yield stress increases, but the variation is smaller than the other test criteria. The tendency of the tensile strength and elongation variation depending on the test conditions was difficult to understand.