• 열처리공학회지
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• 제20권4호
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• pp.181-186
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• 2007

Effect of heat treatment conditions on formability and property of warm hydroformed parts for Al 6061 extruded tubes was investigated in this study. For the investigation, as-extruded, fully annealed and T6-treated Al 6061 seamless tubes were prepared. To evaluate the warm hydroformability, uni-axial tensile test and free bulge test were performed at various pre- and post-heat treatment conditions. And the tensile test specimens were obtained from hexagonal prototype hydroformed parts at $250^{\circ}C$. As a result, hydroformability of fully annealed tube is 25% higher than that of extruded tube. The tensile strength and strain of hydroformed part reach to 330 MPa and 12%, respectively, when the part was T6 treated after warm hydroforming. However, the hydroformability of T6 pre-treated tube is relatively low due to the decreased elongation, 8%.

• 한국도로학회논문집
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• 제16권6호
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• pp.19-25
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• 2014

PURPOSES : This study was performed to evaluate the possibility of Indirect Tensile Strength (ITS) as a testing method that can predict cracking on pavement. METHODS : Three asphalt binders and one kind of aggregate were used in this study, and all asphalt mixtures were produced using Gyratory Compactor followed asphalt mix design. The ITS test was performed for the mixture which are artificially short-term aged using the oven. The ITS properties were analyzed by air void, compaction temperature, asphalt content, and asphalt binder. RESULTS : The results of this study indicated that (1) the compaction temperature did not show relationship with the ITS test; (2) there was no specific trend between the asphalt content and the ITS test; (3) the ITS could reveal the property of kinds of asphalt binders; (4) the asphalt mixture that were produced at optimum temperature suggested by manufacturer did not exhibit optimum result for all asphalt binder. CONCLUSIONS : The possibility of ITS was confirmed from this study for replacement of the Marshall Stability method. However, it needs to perform in further studies of aggregate and compaction property to suggest a new ITS standard value.

• 한국주조공학회지
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• 제35권6호
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• pp.163-169
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• 2015

This study reports the influence of gadolinium (Gd) addition on mechanical and corrosion properties of 2205 duplex stainless steel. In all alloys produced, regardless of the initial Gd content, Gd-based inclusions were well distributed in the duplex stainless steel matrix. As the Gd content increased from 0 wt% to 0.19 wt%, the ultimate tensile strength and hardness of the alloy increased from 630 MPa to 977 MPa and from 57 to 61, respectively, while elastic modulus, tensile elongation and impact energy of the alloy decreased. The critical crevice temperatures of Alloy1, Alloy2 and Alloy3 were $20^{\circ}C$, $20^{\circ}C$ and $15^{\circ}C$, respectively.

• 대한금속재료학회지
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• 제49권2호
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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.

• 한국초전도ㆍ저온공학회논문지
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• 제25권3호
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• pp.34-37
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• 2023

The practical application of REBCO coated conductor (CC) tapes, vital for energy transmission (e.g., cable application) and high-field magnets (e.g., coil application), necessitates efficient and simple quality assessment procedures. This study introduces a systematic approach to assess the electromechanical properties of REBCO CC tapes under 77 K and self-field conditions. The approach involves customized tensile and bending tests that clarify the critical current (I_c) response of the CC tapes under mechanical loads induced by tension and bending. This study measures the retained Ic values of commercially available GdBCO CC tapes under 250 MPa tensile stress and 40 mm bending diameter. Through experimentation, the study demonstrates the resilience of these tapes and their suitability for applications. By presenting a simplified stress-based analysis and a bending test of the tapes, the study contributes to effective quality assessment methods for the development of practical superconducting products.

• Journal of the Korean Wood Science and Technology
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• 제42권4호
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• pp.376-384
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• 2014

본 연구는 가소화 전분필름의 열적 및 강도적 성질에 미치는 두 종류의 나노셀룰로오스, 즉 마이크로피브릴 셀룰로오스(MFC)와 셀룰로오스 나노크리스탈(CNC) 및 아민화전분의 첨가영향을 조사하였다. 글리세롤(23 wt%)을 전분의 가소제로 사용하였으며, 나노셀룰로오스를 각각 1, 5, 10, 30 중량부(phr)를 첨가하여 나노필름을 제조하였다. 나노셀룰로오스의 첨가량이 증가함에 따라 인장강도 및 탄성율은 비례적으로 증가하였으나 신장율은 저하하였다. 또한, MFC 강화필름의 강도적 성질이 CNC 강화필름보다 큰 값을 나타냈다. 제지용 사이즈제로 사용하는 아민화전분의 소량 첨가는 강도적 성질의 향상에 양호한 영향을 미쳤다. MFC 강화 전분나노필름의 TGA에 의한 열적 안정성은 MFC (30 phr)의 첨가에 의하여 향상되었으며, 아민화전분 첨가 나노필름의 경우에도 MFC를 첨가함으로써 향상되었다.

• Journal of Welding and Joining
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• 제25권2호
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• pp.55-61
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• 2007

Flash butt weldability of 590MPa dual phase steel is carried out under micro metallographical examination and macro mechanical property tests. The objective of present study is to investigate the cause that brings on bond line fracture, and is to improve mechanical properties of the flash butt welded joint. The joint of flash butt welding has a superior tensile property, but has bad formability due to oxide formed at bond interface. The HAZ softening in the weld joint does not show. It was found that mechanical properties were increased with optimizing welding parameters and making application of oil dripping and post-weld heat treatment.

• 한국염색가공학회지
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• 제21권3호
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• pp.43-48
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• 2009

This paper surveys the mechanical properties of nylon high tenacity coarse yarn and fabric for military and technical textiles. For this purpose, 6 kinds of yarns and 2 kinds of fabrics are prepared. The yarn physical properties such as yarn count, thermal shrinkages, and tensile properties are measured and discussed with the characteristics of the domestic and imported yarns. And, the physical and mechanical properties of these fabrics are also measured and discussed with the usage of these fabrics in the military and technical textiles fields. Hereafter, the differences of physical properties between domestic and foreign yarn specimens for high functional military and technical fabrics are estimated through this study.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1104-1110
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• 2003

There are many applications of nanostructures, have been suggested by lots of researchers. It is highly required to measure the properties of nano-sized materials for design and fabrication of the nanostructures. In this paper, several techniques for measuring the mechanical properties of nano-structures are presented laying emphasis on the activity of Nano Property Measurement Team in KIMM. Some advanced applications of nano-indenter are described for measuring elastic, visco-elastic, frictional and adhesive properties as well as the standard methods of it. Micro-tensile test technique with accurate in-plane strain measurement method is also presented and its role in the property measurement of nanostructures is discussed.

• Macromolecular Research
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• 제13권3호
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• pp.194-205
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• 2005

The network structure of Ni-coated carbon black (NCB) composites filled with phenolic resin was investigated by means of using scanning electron microscopy, viscosity, interfacial tension, shrinkability, Flory-Huggins interaction parameters, and swelling index. The electrical properties of the composites have been characterized by measurement of the specific conductivity as a function of temperature. Additionally, the variation of conductivity with temperature for the composites has been reported and analyzed in terms of the dilution volume fraction, relative volume expansion, and barrier heights energy. The thermal stability of phenolic-NCB composites has been also studied by means of the voltage cycle processes. The experimental data of EMI wave shielding were analyzed and compared with theoretical calculations. The mechanical properties such as tensile strength, tensile modulus, hardness and elongation at break (EB) of NCB-phenolic resin composites were also investigated.