• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.211-214
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• 2008

The Mechanical properties of steel in hot strip mill were associated with the various rolling conditions such as alloy composition, plastic deformation, cooling history and so on. After coiling process of strip which is the end of hot rolling process, the coil can be the final product or can be applied by another process, that is, cold rolling or skin pass rolling with the additional changes of mechanical properties. Skin pass rolling process with the small reduction affects the mechanical properties of the strip. Because many kinds of hot strips are delivered to the customers after the skin pass process, it is important for us to know the skin pass effects for the mechanical properties of the hot rolling strip. In this study, the variations of mechanical properties of the strip after the skin pass rolling will be discussed. Then, the mathematical model will be proposed for the prediction of mechanical properties of the final products with the comparison between measured and calculated values.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.669-674
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• 2020

Liquid-phase-sintered (LPS) SiC materials were briefly examined with their microstructure and mechanical property. Especially, effect of high-temperature exposure on the tendency of fracture toughness of LPS-SiC were introduced. The LPS-SiC was fabricated in hot-press by sintering powder mixture of sub-micron SiC and sintering additives of Al₂O₃-Y₂O₃. LPS-SiC represented dense morphology and SiC grain-growth with some amount of micro-pores and clustered additives as pore-filling. The strength of LPS-SiC might affected by distribution of micro-pores. LPS-SiC tended to decrease fracture toughness depending on increasing exposure temperature and time.

• Steel and Composite Structures
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• v.17 no.1
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• pp.105-121
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• 2014

A fundamental limitation of steel structures is the decrease in their load-bearing capacity at high temperatures in fire situations such that structural members may require some additional treatment for fire resistance. In this regard, this paper evaluates the structural stability of fire-resistant steel, introduced in the late 1999s, through tensile coupon tests and proposes some experimental equations for the yield stress, the elastic modulus, and specific heat. The surface temperature, deflection, and maximum stress of fire-resistant steel H-section columns were calculated using their own mechanical and thermal properties. According to a comparison of mechanical properties between fire-resistant steel and Eurocode 3, the former outperformed the latter, and based on a comparison of structural performance between fire-resistant steel and ordinary structural steel of equivalent mechanical properties at room temperature, the former had greater structural stability than the latter through $900^{\circ}C$.

• Journal of Welding and Joining
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• v.25 no.2
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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.

• Fashion & Textile Research Journal
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• v.13 no.2
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• pp.279-284
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• 2011

In this study, the process of preparation nonwoven with coated carbon nano fibers (CNFs) /poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) composite solution is described. The various contents of CNFs/PVDF-HFP composite coated nonwoven were prepared and characterized by morphological, mechanical, and electrical methods. Nonwovens are coated with CNFs/PVDF-HFP composite solution and decreased the pick up ratio with increasing CNFs contents in range from 0% to 16%. In the results of SEM images, it was clear that the CNFs were evenly distributed in coated nonwoven by SEM images, the existence of CNFs in coated nonwoven was confirmed regularly. The mechanical properties of various contents of CNFs/PVDF-HFP coated nonwoven were examined. The tensile linearity and compression linearity increased with increasing CNFs contents. The electrical properties of the CNFs/PVDF-HFP coated nonwoven increased with increasing CNFs contents.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.2
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• pp.641-648
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• 1996

Thermophoretic particle deposition on a circular cylinder in a uniform laminar air flow was numerically investigated using a control volume method based on the generalized non-orthogonal coordinate system. Variation of air properties due to the change of temperature was taken into account. Effects of variable property on the distribution of heat transfer and deposition rates of particle were discussed. A new correlation of thermophoretic particle deposition on a circular cylinder was proposed in the present study.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.4
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• pp.398-403
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• 2011

Terfenol-D is one of several magnetostrictive materials with property of converting energy into mechanical motion, and vice versa. Magnetostriction is the property that causes certain ferromagnetic materials to change shape in a magnetic field. Terfenol-D is said to produce giant magnetostriction, strain greater than any other commercially available smart material. In this paper, fundamental characteristics analysis of giant magnetostrictive materials(Terfenol-D) has been investigated. The magnetic field analysis is carried out by using finite element method simulation ANSYS. The results show 223N in force and 9.5T in maximum magnetic flux density and 7.56 $10^6A/m$ in maximum magnetic field intensity 1A current. Through the analysis, basic data of Terfenol-D for the application of mechanical system are obtained.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.102.2-102.2
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• 2012

Different layers of zirconium nitride (ZrN) and hydroxyapatite (HA) coatings were prepared on cp Ti substrate for biomedical applications. The main idea is to improve the mechanical strength as well as the biocompatibility of the coating. ZrN is known for its high mechanical strength, corrosion resistance. HA is well known for its biocompatibility properties. Hence, in this study, both materials were coated on a cp Ti substrate with bottom layer with ZrN for good bonding with substrate and the top layer with HA for induce bioactivity. Middle layer was formed by a composite of HA and ZrN. Detail analyses of the layered coatings for its structural, morphological, topographical properties were carried out. Then the mechanical property of the layered coatings was analyzed by nanoindentation. Biomimetic growths of apatite on the functionally graded coatings were determined by simulated body fluid method. This study provides promising results to use this kind of coatings in biomedical field.

• Journal of the Korean Ceramic Society
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• v.35 no.12
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• pp.1343-1350
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• 1998

A study is made of mechanical properties of unglazed matrix as a funtion of sintering temperature and crack patterns in layer structur pottery consisting of glaze and substrate and in matrix which is sintered at 120$0^{\circ}C$ and 130$0^{\circ}C$ respectively. The mechanical properties of matrix are increased due to density and vitrification to 130$0^{\circ}C$ The interface of glazed bilayer reveals the reactive intermediate layer. Herzian indentation testing is used to investigate the evolution of damage modes as a function of load. In the materials sintered at 120$0^{\circ}C$ quasi-plastic deformation is developed at the matrix and the cone-like cracks initiate at the glazing top surface and additionally upward-extending transverse cracks initiate at the internal in-just initiate at the glazing top surface which pass through the interface with increasing of indentation load. Finally the dominant damage mode shifts from substrate quasi-plasticity to coating fracture with increasing sintering temperature.

• Transactions of Materials Processing
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• v.13 no.3
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• pp.242-247
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• 2004

Literature review on reliability test method for developing high performance optical/thermofluidic components. Since the miniaturization by the conventional mechanical process is limited to milli-structure, i.e. $10^{-3}m$, new technology for fabricating of mechanical components is needed to match cost, reliability, and integrability criteria of micro-structure. Although numbers of various researches on MEMS/MOEMS devices and components, including material characterization, design and optimization, system validation, etc., the lack of standards and specifications make the researches and developments difficult. For that reason, this paper is intended to propose the methods of reliability test for measuring the mechanical property of optical/ thermofluidic components.