• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.85-90
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• 2018

This paper compares the adaptive eualization performance of CR-MMA (Constellation Reduction-MMA) and CR-MMA (Constellation Matching-MMA) in order to minimization of intersymbol interference that is occur in channel for 2-dimensional QAM signal. For obtain the error signal in order to updating the tap coefficient of conventional adaptive equalization algorithm MMA, the CR-MMA converts the constellation reduction concept of high order 2-dimensional QAM nonconstant modulus signal to constant modulus signal and the CM-MMA use the constellation matchine error concept in order to force the matching the $2^{nd}$ and $4^{th}$ cumulant of equalizer output and transmitted signal constellation. By applying the different method for getting the error signal, these algorithm are possible to obtain the improved equalization performance compared to the conventional MMA algorithm, the improved performance of CR-MMA and CM-MMA were compared by computer simulation in this paper. As a result of simulation, the CM-MMA has more better performance in the equalizer internal performance than CR-MMA, but not in equalizer external performance as in SER.

• Journal of the Korean Ceramic Society
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• v.47 no.2
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• pp.122-126
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• 2010

In this article photoluminescence of the $Al_2O_3:xCr_2O_3$ solid solutions prepared by solid state reaction method are represented. The effect of $Cr_2O_3$-activator concentration and heat treatment time on the PL characteristics have been discussed in conjunction with microstructure of phosphor samples. The $Al_2O_3:xCr_2O_3$ phosphors show the highest PL intensity at x=0.003 mole when the samples are reacted at $1600^{\circ}C$ for 5 h. The PL emission and absorption spectra show the maximum peaks at 698 nm and at 398 nm respectively. The CIE color coordinate is (x=0.646, y=0.316) at 0.003 mole $Cr_2O_3$, which value is very close to the NTSC coordinate of red color. This characteristic feature of $Al_2O_3:xCr_2O_3$ has been applied for an additive to improve the color characteristic of other red phosphor $LiEuW_2O_8$ which has a relatively poor color purity with an emission peak centered at 615 nm and with a CIE coordinate (x=0.530, y=0.280). The $Al_2O_3:0.003Cr_2O_3$ phosphor has been mixed with the $LiEuW_2O_8$ phosphor powder and the PL characteristics and CIE color coordinates are characterized. The $Al_2O_3:xCr_2O_3$ phosphor was found effective for improving the CRI (color rendering index) of $LiEuW_2O_8$ phosphor.

• Journal of the Korean institute of surface engineering
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• v.47 no.2
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• pp.93-98
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• 2014

The $Cr_2AlC$ carbides oxidized at 700, 850 and $1000^{\circ}C$ in air from 70 hours up to 360 days. They oxidized according to the reaction; $Cr_2AlC+O_2{\rightarrow}{\alpha}-Al_2O_3+CO(g)$. The scales consisted primarily of the thin, essentially pure $Al_2O_3$ layer and the underlying Al-dissolved $Cr_7C_3$ layer. They grew via the outward diffusion of Al and carbon, and the inward diffusion of oxygen. The oxidation resistance of $Cr_2AlC$ was excellent due to the formation of the protective $Al_2O_3$ layer. Even when $Cr_2AlC$ oxidized at $1000^{\circ}C$ for 360 days, the ${\alpha}-Al_2O_3$ layer was only about 4 ${\mu}m$-thick.

• Korean Journal of Mathematics
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• v.6 no.2
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• pp.243-257
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• 1998

The purpose of this paper is to give some characterizations of $n$-dimensional CR-submanifolds with ($n-1$) CR-dimension immersed in a complex projective space $CP^{\frac{n+2}{2}}$, in terms of the Riemannian curvature tensor R.

• Journal of Technologic Dentistry
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• v.35 no.2
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• pp.105-112
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• 2013

Purpose: This study was to analyze the castability, surface oxide characteristic of Co-Cr alloy for porcelain fused to metal crown and the bonding strength of porcelain fused to metal crown. Co-Cr and Ni-Cr alloy for porcelain fused to metal crown was used for tests of the castability and surface oxide state and shear bonding strength by various porcelain. The aim of this study was to suggest the differences of result according to Co-Cr and Ni-Cr alloy. Methods: The kinds of alloy as test specimen was Co-Cr and Ni-Cr alloy. The castability index on the alloy specimens. The surfaces of two alloys were analyzed by SEM and EDX in order to observe oxide characteristic. And the shear test was performed by MTS. Results: The castability index of Co-Cr alloy was 96.8% and Ni-Cr alloy was 94.4%. The strongest bonding strength of Co-Cr alloy was shown 67.37 MPa. Conclusion: The shear bonding strength between Co-Cr alloy and EX3 porcelain was the strongest comparing with others. And all of each alloy was indicated as same level about the castability.

• Journal of Korea Foundry Society
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• v.7 no.2
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• pp.108-113
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• 1987

Al-Cr alloy with composition in the range from 1.5 wt% to 10 wt% Cr were rapidly solidified from the melt by the single roller method. The supersaturated solid solution was obtained up to 6 wt% Cr in Al-Cr alloy for $20{\mu}m$ thickness. Lattice parameter decreased with increasing Cr content at the rate of 0.00456A per wt% Cr up to 6 wt% Cr. Microhardness increased with increasing Cr content at the rate of $10\;Kg/mm^2$ per wt% Cr up to 6 wt% Cr. Microhardness measurements on the Al-6 wt% Cr supersaturated solid solution annealed isothermally showed no sign of age hardening. Decomposition temperature, determined by lattice parameter changes and microhardness changes, was $470^{\circ}C$ for Al-6 wt% Cr supersaturated solid solution. Transmission electron microscopy showed that decomposition within one hour below $400^{\circ}C$ occurred at grain boundaries only, and also the additional decomposition within grains being evident at $450^{\circ}C$ The coarse precipitate structure showed at $500^{\circ}C$ and $550^{\circ}C$, respectively. The coarse precipitate structure is considered $Al_7Cr$.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.192-193
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• 2009

CrN 코팅막은 고온에서 치밀한 Cr2O3 확산방지막을 형성함으로 $800^{\circ}C$까지 기계적성질을 유지할 수 있다. 본 실험에서는 Ar, N2, 그리고 $O_2$ 가스 분위기에서 AIP(Arc Ion Plating) 기법에 의해 다양한 조성의 Cr-O-N 박막을 Si(200)과 AISI 304 기판 위에 증착되었다. Cr-O-N 코팅막은 47.4at% 미만의 산소함량을 포함 할 때까지 B1구조를 유지하였고 코팅막 내 산소함량 24.6at%에서는 강한 XRD peak intensification을 나타내었다. 47.4at%에서는 결정상을 전혀 찾아볼 수 없는 전이구조를 나타내었고, 그 이상의 산소함량에서는 Cr22O3 결정상을 나타내었다. Cr-O(17at%)-N 조성의 코팅막에서는 (200)배향의 Grain 크기 증가 및 압축잔류응력이 증가하였으나, 그 이상의 산소함량에서는 점차 감소하였다. Cr-O(24.6at%)-N 조성의 코팅막이 가장 높은 경도를 나타내었고, 산소함량이 증가할수록 점차 향상된 마찰특성을 보였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.8
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• pp.714-719
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• 2005

NiCr thin film was deposited by DC magnetron sputtering on $A;_2O_3$/Si substrate with NiCr (80:20) alloy target. NiCr thin films were annealed at $300^{\circ}C,\;400^{\circ}C,\;500^{\circ}C,\;600^{\circ}C,\;and\;700^{\circ}C$ for 6 hr in $H_2$ after annealing at $500^{\circ}C$ for 6hr in air atmosphere, respectively. To analyze NiCr thin film properties, the changes of its micro structure were Investigated through field emission scanning electron microscope (FESEM). X-ray photoelectron spectroscopy (XPS) was used to analyze a surface of NiCr thin film. Resistance of NiCr thin film was measured by 4-point probe technique. The generated heats were measured by infrared thermometer through the application of DC voltage (5 V/l2 V). NiCr thin film treated by gradational double annealing process had uniform and small grains. Maximum temperature generated heat by NiCr micro heater was $173^{\circ}C$. We expect that our results will be a useful reference in the realization of NiCr micro heater.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.8
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• pp.704-710
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• 2000

Metal electrode materials for plasma display panel should have low electrical resistivity in order to maintain stable gas discharge and have fast response time. They should also hae good film uniformity adhesion and thermal stability. In this study Cr/Cu/Cr metal electrode structure is formed by DC magnetron sputtering. Cr and Cu films were deposited on ITO coated glasses with various DC power density and main pressures as the major parameters. After metal electrodes were formed a heat treatment was followed at 55$0^{\circ}C$ for 20 min in a vacuum furnace. The intrinsic stress of the sputtered Cr film passed a tensile stress maximum decreased and then became compressive with further increasing DC power density. Also with increasing the main pressure stress turned from compression to tension. After heat the treatment the electrical resistivity of the sputtered Cu film of 2${\mu}{\textrm}{m}$ in thickness prepared at 1 motor with the applied power density of 3.70 W/cm$^2$was 2.68 $\mu$$\Omega$.cm With increasing the main pressure the DC magnetron sputtered Cu film became more open structure. The heat treatment decreased the surface roughness of the sputtered Cr/Cu/Cr metal electrodes.

• Journal of the Korean institute of surface engineering
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• v.40 no.5
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• pp.219-224
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• 2007

The corrosion characteristics of Fe-18Cr-10Ni steels were studied between $600^{\circ}C$ and $1000^{\circ}C$ in Ar+(0.2, 1)%$SG_2$ gas for up to 300 hr in order to employ Fe-18Cr-10Ni steels in the coal-fired power plants. The corrosion resistance of Fe-18Cr-10Ni steels was good due mainly to the high amount of Cr, which formed $Cr_2O_3$ from the initial corrosion stage. Fe in the steels corroded to mainly $Fe_2O_3$ and $Fe_3O_4$. Ni was not susceptible to corrosion under the current corrosion condition. Relatively thin, single-layered scales formed.