• Journal of the Korean Society of Industry Convergence
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• v.9 no.1
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• pp.51-59
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• 2006

The study is diagnosis about fatigue failure phenomenon of heating coil spring (sup9) and heat treatment method that is used to crusher. Because more than 80~90% of damage announcement of breakdown of machine and construction is been caused in fatigue present state, fatigue failure became important leading person at design. Calculated design load is imposed repeatedly that fatigue breakdown is safe. Is phenomenon that change load is imposed in the construction continuously. Used coil spring applies heat 30minute by Quenching temperature $860^{\circ}C$ if see manufacturing process and temperature of gasoline of $50^{\circ}C$ keep after quench that know tempering a $460^{\circ}C$ 90minute a product be. If doto apply heat $950^{\circ}C$ material at rolling process historically before quenching, austenite formation clay pipe being done AGS(Austenite Grain Size) by 2.5~4 become. Apply heat quenching 30minute by $820^{\circ}C$ by improvement method and after quench that keep $50^{\circ}C$ in oil tempering if do $450^{\circ}C$, 90minute spring ideal formation sorbite formation of the river form and condition that satisfy most more than AGS 7 appeared. Also, we can secure authoritativeness through MT since shot peening processing.

• Journal of the Korean Society for Heat Treatment
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• v.7 no.4
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• pp.233-243
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• 1994

Constitutive relation of thermoelasto-plastic material undergoing phase transformation during quenching process were developed on the basic of continuum thermodynamics. The metallic structure, temperature and residual stresses distributions were numerically calculated by the finite element technique. The metallic structure were defined by transformation from austenite to pearlite and characterized as a fuction of thermal history and mixture rule of phase. On the distribution of thermal stress along the radial direction, axial and tangential stresses are compressive in the surface, and tential in the inner part. Radial stress is tensile in the whole body. The reversion of residual stress takes plase at 11.5~15.5mm from the center.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.240-243
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• 1997

The Quenching and Self Tempering (QST) rolling is treated in terms of an advance process on Controlled Rolling and Cooling Technology (CRCT). In the analysis, the effect of this process is governed by both quenching and finishing conditions in the related with temperature. The objective of the QST model is to simulate the temperature gradient of the stock being rolled in the rolling mill. A comparison of computer simulated and manufactured micro structure as well as mechanical properties shows a good consistency. The micro structure of this high-strength round bar consists of tempered martensite and ferrite + pearlite phases.

• Journal of the Korean Society for Heat Treatment
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• v.2 no.2
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• pp.11-16
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• 1989

Understanding and control of thermal history of heat-treated components are very important in heat treating process. A computer program was developed for prediction of thermal history in quenching process with various cooling media and agitation conditions. Computer simulation of heat flow in quenching treatment of spur gear of SCM 22 H was carried out by two and three dimensional finite difference method. Distributions of microstructure and hardness in heat-treated spur gear were predicted by computer simulation, and the results showed a good agreement with the experiments. It was concluded that the

• Journal of the Korean Society for Heat Treatment
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• v.8 no.1
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• pp.12-23
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• 1995

In this a set of constitutive equation relevant to the analysis of thermo-elasto-plastic materials with phase transformation during quenching process was presented on the basis of continuum thermo-dynamic. In calculating the transient thermal stresses, temperature between coolant and specimen(SM45C) surface was determined from the heat transfer coefficient. A calculation was made for specimen with 40mm in diameter quenched in coolant from $820^{\circ}C$ and the results are as follow. Stresses at starting point of transformation always show the maximum tensile value. Reverse of stresses takes place after completion of transformation of inner part at specimen.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.497-504
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• 1998

The manufacturing processes of the head hardened rails and the principles of the heat treatment for carbon steels are introduced in this paper, To get the good wear resistance of the rail, many kinds of microstructure had been developed for the rail head hardening. One of these is the tempered martensitic structure, which is very hard but brittle because of Quenching-Tempering Process. Another is the fine pearlitic structure by Slack Quenching. Now Banitic structure steels are emerging as a potential new material to replace eutectoid pearlitic steels for rail. The main reason of this change is due to the limitaion of pearlitic microstructure with regard to mechanical properties and wear resistances of railway rails.

• Elastomers and Composites
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• v.54 no.3
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• pp.201-208
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• 2019

Superabsorbent hydrogel (SAH) is a lightly crosslinked hydrophilic functional polymer material comprising a flexible chain structure, which can absorb and retain high amounts of water or aqueous fluids even under high pressure. Therefore, it is important to improve their characteristics such as absorption performance, residual monomer content, and water permeability. SAH nanocomposites were prepared using clay mineral as an inorganic filler and the influence of post-treatment processes such as quenching and aging process on their properties was studied. In addition, surface-crosslinking process was applied to improve the absorption performance associated with mechanical properties and water permeability. The structure of the SAH was characterized using attenuated total reflectance Fourier transform infrared spectroscopy, X-ray diffraction analysis, and scanning electron microscopy.

• Journal of Ocean Engineering and Technology
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• v.25 no.6
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• pp.97-104
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• 2011

Modified C95600 bronze contains Fe component of 0.7 weight percentage besides Cu-7Al-2.5Si composition. The shape of centrifugal cast is a circular pipe with thick wall. Specimens machined from the centrifugal cast were quenched in oil after isothermal holding at a given heat treatment temperature in the range of $700{\sim}900^{\circ}C$. Mechanical properties and structural morphology are depended on the quenching heat treatment temperature regardless of isothermal holding time. Tensile strength or Brinell hardness is increased with increasing heat treatment temperature. The microstructure caused by quenching contains mixing phases of ${\alpha}+{\beta}'+FeSi+{\kappa}$ which martensite of ${\beta}'$ phase has been transformed from ${\beta}$ phase. Effect of isothermal holding temperature on mechanical properties in case of quenching heat treatment attributes to the change of volume fraction of ${\beta}'$ on the structural morphology. Mechanical characteristics of specimen, initially quenched from $850^{\circ}C$, and then tempered at $500^{\circ}C$, does not show an obvious softening indication, because disappearance of ${\beta}'$ during tempering process can be compensated by precipitation of brittle phase ${\gamma}$.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2253-2259
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• 2011

The self-assembly of one novel organic complex based on chlorogenic acid (HCA) and 2,2'-bipyridine (2,2'-bipy) has been synthesized and characterized. The complex achieved by hydrogen-bonding interactions, adopted a 1:1 stoichiometry in a solid state. The proton transfer occurred from the carboxyl oxygen to the aromatic nitrogen atom to form salts CA${\cdot}$(2,2'-Hbipy), the 2,2'-Hbipy molecule individually occupies the pseudo-tetragonum that is formed with CA. In this paper, the interactions of CA${\cdot}$(2,2'-Hbipy) with bovine serum albumin (BSA) were studied by fluorescence spectrometry. For CA${\cdot}$(2,2'-Hbipy), HCA and 2,2'-bipy, the average quenching constants for BSA were $2.4384{\times}10^4$, $4.653{\times}10^3$, and $3.059{\times}10^3\;L{\cdot}mol^{-1}$, respectively. The mechanism for protein fluorescence quenching is apparently governed by a static quenching process. The Stern-Volmer quenching constants and corresponding thermodynamic parameters ${\Delta}$H, ${\Delta}$G and ${\Delta}$S were calculated. The binding constants and the number of binding sites were also investigated. The conformational changes of BSA were observed from synchronous fluorescence spectra.

• Korean Journal of Materials Research
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• v.22 no.10
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• pp.513-518
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• 2012

Recently, automobile parts have been required to have high strength and toughness to allow for weight lightening or improved stability. But, traditional micro-alloyed steel cannot be applied in automobile parts. In this study, we considered the influence of quenching temperature and cooling rate for specimens fabricated by vacuum induction furnace. Directly quenched micro-alloyed steel for hot forging can be controlled according to its micro structure and the heat-treatment process. Low carbon steel, as well as alloying elements for improvement of strength and toughness, was used to obtain optimized conditions. After hot forging at $1,200^{\circ}C$, the ideal mechanical properties (tensile strength ${\geq}$ 1,000 MPa, Charpy impact value ${\geq}\;100\;J/cm^2$) can be achieved by using optimized conditions (quenching temperature : 925 to $1,050^{\circ}C$, cooling rate : ${\geq}\;5^{\circ}C/sec$). The difference of impact value according to cooling rate can be influenced by the microstructure. A fine lath martensite micro structure is formed at a cooling rate of over $5^{\circ}C/sec$. On the other hand, the second phase of the M-A constituent microstructure is the cause of crack initiation under the cooling rate of $5^{\circ}C/sec$.