• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3800-3805
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• 2012

Infrared(IR) reflective black cool pigment and paint which is used for interior/exterior materials(IR reflectance >30%) to prevent heat island effect and to increase energy efficiency were studied. Cool pigment was synthesized using mixture of $Fe_2O_3$ and $Cr_2O_3$ with calcination from 900 to $1,200^{\circ}C$. Cool paint was prepared by formulation of cool pigment, acrylic resins, and other additives. Results showed that optimum color fixation of pigment obtained by mole ratio of Fe to Cr was 0.9 with calcination temperature at $1,000^{\circ}C$. The cool paint formulated by 20% pigment and 1.5% dispersive additive with $125{\mu}m$ thickness of coated layer showed optimum IR reflectance. Temperature difference on surface between cool paint and ordinary paint(STD) was $36.5^{\circ}C$ and IR reflectance(TSR) was 39.3% at wavelength from 700 to 2,500nm. And color change was not detected during 500hrs weathering test.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.3
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• pp.128-136
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• 2023

In this study, the effects of heat treatment on the nano-scale creep behavior of CoCrFeMnNi high-entropy alloy (HEA) processed by high-pressure torsion (HPT) was investigated through nanoindentation technique. Nanoindentation experiments with a Berkovich indenter were performed on HPT-processed alloy subjected to heat treatment at 450℃, revealing that the hardness of the HPT-processed alloy (HPT sample) significantly increased with the heat treatment time. The heat treatment-induced microstructural change in HPT-processed alloy was analyzed using transmission electron microscopy, which showed the nano-sized Cr-, NiMn-, and FeCo-rich phases were formed in the HPT-processed alloy subjected to 10 hours of heat treatment (HPT+10A sample). To compare the creep behavior of HPT and HPT+10A samples, constant load nanoindentation creep experiments were performed using spherical indentation indenters with two different radii. It was revealed that the predominant mechanism for creep highly depended on the applied stress level. At low stress level, both HPT and HPT+10A samples were dominated by Coble creep. At high stress level, however, the mechanism transformed to dislocation creep for HPT sample, but continued to be Coble creep for HPT+10A sample, leading to higher creep resistance in the HPT+10A sample.

• Korean Journal of Materials Research
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• v.10 no.7
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• pp.489-492
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• 2000

Three different white cast irons alloyed with Cr and Si were prepared in order to study their distribution be-havior in matrices and carbides. The specimens were produced using a 15kg-capacity high frequency induction fur-nace. Melts were super-heated to $1600^{\circ}C$, and poured at $1550^{\circ}C$ into a pepset mold. Three combinations of the alloys were selected so as to observe the distribution behavior of Cr and Si : 0.5%C-25.0%Cr-1.0%Si(alloy No. 1), 0.5%C-5.0%Cr-1.0%Si(alloy No. 2) and 2.0%C-5.0%Cr-1.0%Si(alloy No. 3). Cellular $M_7C_3$ carbides-$\delta$ferrite eutectic were developed at $\delta$ferrite liquid interfaces in the alloy No. 1 while only traces of $M_7C_3$ carbides-$\delta$ferrite eutectic were precipitated in the alloy No. 2. With the addition of 2.0% C and 5.0% Cr, ledeburitic $M_3C$ carbides instead of cellular $M_7C_3$ carbides were precipitated in the alloy No. 3. Cr was distributed preferentially to the $M_7C_3$ carbides rather than to the matrix structure while more Si was partitioned in the matrix structure rather than the $M_7C_3$ carbides. $K^m$ for Cr was ranged from 0.56 to 0.68 while that for Si was from 1.12 to 1.28. $K^m$ for Cr had a lower value with increased carbon contents. The mass percent of Cr was higher in the $M_7C_3$ carbides with increased Cr contents.

• Journal of the Korean Magnetics Society
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• v.8 no.6
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• pp.374-379
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• 1998

$Mn_1-xCr_xPt_3$ alloy films have been prepared by depositing (Mn, Cr)/Pt multilayers using a rf magnetron sputterer followed by heat treatment. Small and wide angle x-ray diffractometry, magnetic hysteresis loops and Kerr rotation angle spectra of the films have been measured and used to investigate structural, magnetic and magneto-optic properties of the films. The films had a crystal structure of ordered AuCu$_3$ type and the strong preferred orientation of a (111)plane parallel to the film surface. The saturation magnetization of the films was decreased with Cr content reaching almost zero near x=0.58 and then increased for further increasement of Cr content up to x=0.77 over that stayed almost constant. This indicated that Cr atoms were antiferromagnetically coupled with Mn atoms. The magnetic easy axis of MnPt$_3$(x=0) film was parallel to the film surface but those of the films with x$\geq$0.58 increased as Cr content increased reaching about 4 kOe at x=1(CrPt$_3$). The dependence of the Kerr rotation angle on the Cr content was similar to that of the saturation magnetization on the Cr content. The films with x=0.77 and x=1 showed the larger Kerr rotation angle at the wavelengths of near infrared compared to the magneto-optic recording medium, TbFeCo, currently being used.

• Elastomers and Composites
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• v.38 no.1
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• pp.81-87
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• 2003

In this work, $Fe_3O_4$ (magnetite), conductive filler was prepared from $FeCl_2{\cdot}4H_2O,\;(CH_2)_6N_4$ (hexamethylene tetramine), and $NaNO_2$, followed by mixing with crystallizable chloroprene rubber(CR). The influence of conductive filler content on the properties of the conductive composite was studied and temperature dependence of the electrical conductivity (${\sigma}$) was also investigated. It is found that the percolation threshold concept holds true for the conductive particle-filled composite where ${\sigma}$ indicates a nearly sharp increase when the fraction of magnetite in the mixture exceeds 27%. The temperature dependence of ${\sigma}$ is thermally activated blelow or at the $P_c$. Magnetite acts as reinforcement and conductive filler for CR rubber. Moreover, it is shown that the composite with magnetite of 50 phr gives the most significant mechanical properties for tensile strength and elongation at break, which is due to the formation of optimum physical interlock and crosslinking. The results of 100%, 200%, and 300% moduli suggest that the moduli are related with reinforcement effect of magnetite and viscosity of the blend.

• Journal of Food Hygiene and Safety
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• v.26 no.2
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• pp.107-113
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• 2011

Plantago asiatica L. (PA), which is widely distributed in Korea, Japan and China, has traditionally been used as a popular folk medicine for the treatment of liver diseases. A variety of activities of PA was reported, that is hepatoprotective, anti-inflammatory, anti-glycation and anti-oxidant effect. Ferric nitrilotriacetate (Fe-NTA) is a potent nephrotoxic agent and has been reported to induce renal proximal tubular necrosis. In the present study, pre-treatment with PA extract (PAE) in Wistar rat followed by Fe-NTA i.p. treatment (13.5 mg Fe/kg body weight) was performed to detect the renal protective effect of PAE. Only Fe-NTA treated group showed increases in the level of serum blood urea nitrogen (BUN) and serum creatinine (Cr), and renal tissue malondialdehyde (MDA), product of lipid peroxidation. Moreover, the level of biomarkers indicate the antioxidants status, reduced glutathione (GSH), glutathione-S-transferase (GST) and glutathione reductase (GR) were decreased. However, PAE pre-treated group showed decreases in the levels of serum BUN, serum Cr and renal tissue MDA in concentration dependent manner and increases in the level of GSH, GST and GR. These results are significantly different (p < 0.05) to the other groups. Our data suggest that PAE may be used as an chemopreventive material against Fe-NTA-mediated renal oxidative stress.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.525-532
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• 2014

Since mine wastes were merely dumped in the mine waste dump, they have produced acid mine drainage (AMD). Therefore, main objective of this study was to evaluate the effect of coal combustion products (CCPs) on heavy metal stabilization and detoxification for mine wastes. Total six treatments for incubation test were conducted depending on mixing method (completely mixing and layered). Also, lysimeter experiment was conducted to examine efficiency of polyacrylamide (PAM) on reduction of mine wastes erosion. Result of incubation test showed that concentrations of soluble aluminium (Al) and iron (Fe) in leachate decreased compared to control. The lowest soluble Al and Fe in leachate was observed in 50% mixed treatment (14.2 and $1.03mg\;kg^{-1}$ for Al and Fe respectively) compared to control treatment (253.0 for Al and $52.6mg\;kg^{-1}$ for Fe). The pH of mine wastes (MW) and leachate increased compared to control after mixing with CCPs and ordered as control (MW 6.4, leachate 6.3) < 10% (MW 7.7, leachate 7.1) < 20% (MW 9.0, leachate 7.8) < 30% (MW 9.5, leachate 8.3) < 40% (MW 9.9, leachate 8.5) < 50% (MW 10.5, leachate 8.6). Application of PAM, both in liquid and granular type, dramatically decreased the suspended solid (SS) concentration of CCPs treatments. Reduction of SS loss was ordered as MW70CR30L ($24.4mg\;L^{-1}$) > MW70CR30LPL ($6.7mg\;L^{-1}$) > NT ($3.1mg\;L^{-1}$) > MW70CR30M ($1.6mg\;L^{-1}$) > MW70CR30MPL ($1.1mg\;L^{-1}$) > MW70CR30PGM ($0.7mg\;L^{-1}$) > MW70CR30LPG ($0.5mg\;L^{-1}$) > MW70CR30MPG ($0.4mg\;L^{-1}$). Overall, application of CCPs can be environmental friendly and cost-effective way to remediate coal mine wastes contaminated with heavy metals. In addition, use of PAM could help to prevent the erosion coal mine wastes in mine waste disposal area.

• Journal of the Korean Society for Heat Treatment
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• v.13 no.3
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• pp.151-157
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• 2000

This study aims to investigate the effect of carbon content on the surface nitrogen permeation of 13%Cr-1.8%Al alloyed stainless steels. The surface nitrogen permeation was performed at $1050^{\circ}C{\sim}1200^{\circ}C$ in the $1kg/cm^2$ nitrogen gas atmosphere. The nitrogen permeated surface layer of the specimen containing 0.03%C consists of AlN, martensite and retained austenite phases. while the surface layer of the specimen containing 0.14%C appears the $AlFe_3C_x$ phase including former three phases. The specimen containing 0.14%C shows lower total case depth than that containing 0.03%C at the nitrogen permeation temperatures of $1050^{\circ}C$ and $1100^{\circ}C$, while the total case depth of the specimen containing 0.14%C is remarkably increased at the temperature of $1150^{\circ}C$ and $1200^{\circ}C$ due to the increase in the retained austenite content. Martensitic phase, AlN and $AlFe_3C_x$ precipitate of the nitrogen permeated surface layer cause to increase the surface hardness of 550~600Hv.

• Textile Coloration and Finishing
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• v.6 no.2
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• pp.1-9
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• 1994

In order to study the effect of mordanting on silk fabrics treated with tannin, those fabrics were treated with Al, Cu, Cr, Fe, Sn by pre and post mordanting. It was studied about color change, weighting effect, dgree of photodegradation by pre and post mordanting. The results are as fallows ; 1. On the addition of mordants into mimosa and tannic acid solution, &{\lambda}_{max}& of the former was slightly blue-shifted, on the other hand, &{\lambda}_{max}& of the latter was obviously Red-shifted. 2. In case of Cu, Cr, Pre mordanting, weighting effect were appeared. Weighting effect of silk fabrics treated with Tannic acid increased higher than mimosa by mordanting. 3. In color change, Silk fabrics treated with Mimosa and Tannic acid generally changed to red direction and fabrics treated with tannic acid changed to yellow direction by pre and post mordanting. 4. In the photodegradation, the degree of photodegradation on mordanted fabrics increased. Its degree was slack in Cu, Cr, Post mordanting. On the other hand, Al, Fe, Sn were greate. Silk fabrics treated with Mimosa and Tannic acid got inhibiting effect on photodegradation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.96-99
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• 2001

The formation of soft magnets on paper(SMOP) is proposed for the first time and we have demonstrated it successfully. Iorn was used to form the soft magnet thin film on paper. And Cr layer was used as a buffer layer because the roughness of substrate(paper) is not negligible. The maximum magnetization of Cr/Fe/Cr/Paper(Fe:5000${\AA}$) is about 1000 [emu/cc] and the coercive field is about 80 [Oe.]. It is necessary to reduce the coercivity and to enlarge the magnetization value of SMOP to perform a good soft magnetic characteristics on paper. On, the permalloy material is the proper candidate for its high permeability, low coercivity and high magnetization values.