• Journal of the Korean Ceramic Society
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• v.29 no.2
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• pp.101-106
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• 1992

Sintering behavior, distribution of dopant oxides and electrical properties in the ZnO-Bi2O3-CoO-Sb2O3 and ZnO-Bi2O3-CoO-Sb2O3-Cr2O3 systems were studied. The linear shrinkage of ZnO varistors from 850 to 950$^{\circ}C$ was related to the decomposition reaction (py\longrightarrowsp+Bi2O3) of the pyrochlore phase. In the distribution of the dopant oxides (CoO, Sb2O3, Cr2O3), Co distribute uniformly throughout the sample, the distribution of Sb coincided with small particles (spinel phase, Zn7Sb2O12), and Cr distributed very consistently with Sb. The increase in breakdown voltage, due to the addition of Cr2O3, was not only attributed to the decrease in the ZnO grain size but also to the solution of Cr2O3 in the spinel phase. The leakage current (80% V60 ${\mu}\textrm{A}$) was increased by the addition of Cr2O3.

• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.409-413
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• 2001

In this study, high rate deposition of thick CrNx films was carried out by crossed field unbalanced magnetron sputtering for the special application such as piston ring employed in automobile engine. For the high rate deposition and thick CrNx films formation with thickness of 30$\mu\textrm{m}$, high power density of $35W/cm^2$ in each target was induced and the multi-layer films of Cr/CrN and $\alpha$-Cr/CrN were synthesized by control of $N_2$ flow rate. The dynamic deposition rate of Cr and $\alpha$-CrN film was reached to 0.17$\mu\textrm{m}$/min and 0.12$\mu\textrm{m}$/rnin and the thick CrN$_{x}$. film of 30$\mu\textrm{m}$ could be obtained less than 5 hours. The maximum hardness was obtained above 2200 kg/mm$^2$ and adhesion strength was measured in about 70N, in case of multi-layers films. And the friction coefficient was measured by 0.4, which was similar to the value of CrN single-layer film.m.

• Applied Microscopy
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• v.45 no.1
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• pp.9-15
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• 2015

In the present study, microstructural evolution in CuCrFeNi, CuCrFeNiMn, and CuCrFeNiMnAl alloys has been investigated. The as-cast CuCrFeNi alloy consists of a single fcc phase with the lattice parameter of 0.358 nm, while the as-cast CuCrFeNiMn alloy consists of (bcc+fcc1+fcc2) phases with lattice parameters of 0.287 nm, 0.366 nm, and 0.361 nm. The heat treatment of the cast CuCrFeNiMn alloy results in the different type of microstructure depending on the heat treatment temperature. At $900^{\circ}C$ a new thermodynamically stable phase appears instead of the bcc solid solution phase, while at $1,000^{\circ}C$, the heat treated microstructure is almost same as that in the as-cast state. The addition of Al in CuCrFeNiMn alloy changes the constituent phases from (fcc1+fcc2+bcc) to (bcc1+bcc2).

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.8
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• pp.570-576
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• 1999

$LaCrO_3$-dispersed Cr alloys for metallic interconnector of solid oxide fuel cell have been studied as function of $LaCrO_3$ content in the range of 5 to 25 vol.% in order to examine the electric conductivity, the oxidation property and the thermal expansion behavior of these alloys. The $LaCrO_3$-dispersed Cr alloys showed high electrical conductivities of $3~5\times10^4$ S/cm at room temperature, and as the $LaCrO_3$content increased the conductivity decreased slightly. During the cyclic oxidation test at $1100^{\circ}C$, the weight change of the Cr alloys decreased with increasing number of oxidation cycle except first cycle, which is attributed to the vaporization of the oxide scale. More addition of the $LaCrO_3$ content reduced also the weight change of the Cr alloys. These mean that the oxide scale formed at the surface of the Cr alloy becomes stable with increasing number of oxidation cycle and$LaCrO_3$ content. The measured thermal expansion of the Cr alloy was well fitted to that of 8 mol% $Y_2O_3$-stabilized $ZrO_2$ electrolyte. These results demonstrate that $LaCrO_3$-dispersed Cr alloy is a useful material for metallic interconnector of solid oxide fuel cell.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.142-142
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• 2011

Epitaxial $CuCrO_2$ thin films have been grown on single crystal substrate of c-plane $Al_2O_3$, $SrTiO_3$, YSZ and Quarts by laser ablation of a $CuCrO_2$ target using 266nm radiation from a Nd:YAG laser. X-ray measurements indicate that the $CuCrO_2$ grows epitaxially on all substrate, with its orientation dependent on the kinds of substrates. Most of the layer were polycrystalline with (001), (015) and random as the dominant surface orientation on c-plane YSZ, $SrTiO_3$ and quarts substrate, respectively. (001) orientated $CuCrO_2$ grows on C-plane $Al_2O_3$ and YSZ substrate, (015) orientated $CuCrO_2$ films are found on c-plane $SrTiO_3$ substrate and random orientated $CuCrO_2$ films grows on quarts substrate. These data are compared with the in-plane orientation and the mismatch of the $CuCrO_2$ and each substrate lattices in an attempt to relate the preferred orientation to the plane of the sapphire on which it is grown. Further characterization show that the grain size of the films increases for a substrate temperature increase, whereas the electrical properties of $CuCrO_2$ thin films depend upon their crystalline orientation.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.1-1
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• 2008

본 연구에서는 비대칭 마그네트론 스퍼터링법을 이용하여 Cr-Zr-N 박막을 합성하였다. Cr-Zr-N 박막의 합성을 위해 사용된 타겟은 Cr 과 Zr의 segments(Cr:Zr= 50:50 vol.%)로 구성된 단일 타겟을 사용하였고, 공정조건 중 질소분압을 변화시켜 Cr-Zr-N 박막을 합성하였다. 또한 질소분압 변화에 따른 박막의 물리적, 기계적, 화학적 특성들의 변화를 분석하였으며, 기 발표된 Cr 타겟과 Zr 타겟을 이용하여 합성된 Cr-Zr-N 박막의 특성들과 비교하였다.

• Korean Journal of Acupuncture
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• v.26 no.1
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• pp.125-137
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• 2009

Objectives : We studied anti-allergic effects of Cinnamomi Ramulus(CR) herbal acupuncture and Cinnamomi Ramulus extract. Methods : In vivo, animals were herbal-acupunctured with CR at both ST36s three times for 5 days. Then, we induced active systemic anaphylatic shock using compound 48/80 in ICR mice, and passive cutaneous anaphylaxis using anti-DNP IgE in Sprague Dawley rat. In vitro, we measured cell viability, ${\beta}$ -hexosaminidase release and the expressions of IL-4, TNF-${\alpha}$ and COX-2 mRNA in RBL-2H3 cells after treatment of various concentrations of CR extract. Results : In vivo, CR herbal acupuncture pretreatments at both ST36s inhibited compound 48/80-induced active systemic anaphylatic shock. Passive cutaneous anaphylaxis was inhibited by CR herbal acupuncture pretreatments at both ST36s and optional points. In vitro, CR extract treatments did not affect on cell viability and inhibited ${\beta}$-hexosaminidase release. CR extract treatments also decreased the expressions of IL-4, TNF-${\alpha}$ and COX-2 mRNA in RBL-2H3 cells. Conclusions : These results suggest that CR herbal acupuncture and CR extract should be beneficial in the inhibition of allergic inflammatory response.

• Reproductive and Developmental Biology
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• v.28 no.4
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• pp.253-256
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• 2004

Porcine fibroblasts were transferred into enucleated bovine oocytes for the interspecies nuclear transfer (NT). After NT, the embryos were cultured in three different culture systems. The media used for the experiment were CR1aa and NCSU23. The culture systems used for the experiment were: 1. Culture in CR1aa for 7 days (CR). 2. Culture in CR1aa for 2 days and subsequently in NCSU23 for 5 days (CR-NC). 3. Culture in NCSU23 for 7 days (NC). Bovine (intraspecies) NT group was used as a control. The oocytes in bovine NT group were treated the same as interspecies NT embryos except using bovine fibroblasts as nuclear donors. Regardless of their nuclear origin (interspecies vs bovine), the embryos in CR (68.4% vs 77.2%) and CR-NC (67.8% vs 70.5%) showed better developmental competence to the 2-cell stage (p<0.05) than those in NC (41.0% vs 10.0%). Bovine NT embryos in CR-NC did not develop over the 4-cell stage after the medium replacement, while interspecies NT embryos in CR-NC continued to develop and could reach over the 8-cell stage (12.2%). Blastocysts were only found in bovine NT group (17.4%), but no blastocyst was found in interspecies NT group. This study suggests that the development of interspecies NT embryos mostly depends on their recipient cytoplasm during the culture in vitro.

• Korean Journal of Materials Research
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• v.9 no.1
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• pp.73-80
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• 1999

The effect of alloy compositions of the bond coating on the plasma sprayed-thermal barrier coatings was investigated. The performance of the coating composed of Rene80/NiCrAl/ZrO$_2$-CeO$_2$-Y$_2$O$_3$ and Rene80/CoNiCrAlY/ZrO$_2$-CeO$_2$-Y$_2$O$_3$was evaluated by isothermal and thermal cyclic test in an ambient atmosphere at 115$0^{\circ}C$. The failure of Rene80/NiCrAl/ZrO$_2$-CeO$_2$-Y$_2$O$_3$ coatings was occurred at the bond coating/ceramic coating interface while Rene80/CoNiCrAlY/ZrO$_2$-CeO$_2$-Y$_2$O$_3$ coating was failed at the substrate/bond coating interface after thermal cyclic test. The lifetime of Rene80/NiCrAl/ZrO$_2$-CeO$_2$-Y$_2$O$_3$coatings was longer than Rene80/CoNiCrAlY/ZrO$_2$-CeO$_2$-Y$_2$O$_3$coating. The oxidation rate of the NiCrAl bond coating examined by TGA was lower than CoNiCrAlY bond coatings. In summary, these results suggest that Rene80/CoNiCrAlY/ZrO$_2$-CeO$_2$-Y$_2$O$_3$system as thermal barrier coating be not suitable considering the durability of the coating layer for high temperature oxidation and thermal stress.

• Journal of the Korean Mathematical Society
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• v.37 no.2
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• pp.245-251
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• 2000

Assume that two boundaries of worm domains, which are parpametrizd by harmonic functions, are CR equivalent. Then we determine the Taylor expansion of CR equivalence mapping and get a relation of harmonic functions.