• Journal of the Microelectronics and Packaging Society
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• v.23 no.3
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• pp.69-75
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• 2016

This study investigated the effect of heat treatment conditions not only on the Cr surface crack propagation behaviors but also on the Ni/Cr interfacial reaction characteristics in electroless Ni/electroplated Cr double coating layers on Cu substrate. Clear band layer of Ni-Cr solid solutions were developed at Ni/Cr interface after heat treatment at $750^{\circ}C$ for 6 h. Channeling cracks formed in Cr layer after 1 step heat treatment, that is, heat treatment after Ni/Cr plating, while little channeling cracks formed after 2 step heat treatment, that is, same heat treatments after Ni and Cr plating, respectively, due to residual stress relaxation due to crystallization of Ni layer before Cr plating.

• Journal of the Korean institute of surface engineering
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• v.22 no.1
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• pp.10-16
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• 1989

The properties of carburization on Fe-Cr alloys at 900-96$0^{\circ}C$were investiged. The study on carbide layer which had developed during solid-carburizing was made by use of S.E.M, E.PM.A, and X-ray analyzer. The results obtained were summarized as follows, the composition of carbide and the value of activation energy for the growth of carbide layer on each Fe-Cr alloy were 1) Fe-1Cr : M3C and 52Kcal/mole 2) Fe-3Cr and Fe-5Cr : M7C3and 85-88Kcal/mole 3) Fe-7Cr and Fe-9Cr : (M7C3+M23C6)and 55-66Kcal/mole.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.208-211
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• 2000

We prepared Co-Cr-Ta and Co-Cr-Ta/Ti thin film for perpendicular magnetic recording media by facing targets sputtering system (FTS system). Ti underlayer effects on crystallographic and magnetic characteristics of Co-Cr-Ta perpendicular magnetic recording media have been investigated. Crystallgraphic and magnetic characteristic of prepared thin films were evaluated by x-ray diffractometry(XRD), vibrating sample magnetometer(VSM) and kerr hysteresis loop measurement. The coercivity and anisotropy field increase by introduced Ti underlayer when substrate temperature is higher than 150$^{\circ}C$. The c-axis dispersion angle and grain size of Co-Cr-Ta/Ti thin film is decrease than Co-Cr-Ta when substrate temperature is higher than 100$^{\circ}C$. Consequently, the use of a Ti underlayer highly orientated can be improved crystallographic and magnetic characteristics of Co-Cr -Ta perpendicular media layer.

• Korean Journal of Materials Research
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• v.8 no.6
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• pp.538-544
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• 1998

The spallation of a thermal barrier coating layer depends on the formation of brittle spinels. thermal expansion mismatch between ceramic and metal. the phase transformation of a ceramic layer and residual stress of coating layer. In this work. the formation mechanism of oxide scale formed by oxidation treatment at 90$0^{\circ}C$ was investigated in order to verify oxidation behavior at the interface between E-beam coated $Zr0_2$-7wt.% $Y_20_3$ and plasma sprayed CoNiCrAIY. Some elements distributed in the bond coating layer were selectively oxidized after oxidation. At the initial time of oxidation. AI-depletion zone and $\alpha$-$Al_O_3$,O, were formed at the bond coating layer by the AI-outward diffusion. After layer grew until critical thickness. spinels. $Cr_20$, and $C0_2CrO_4$ by outward diffusion of Co. Cr, Ni were formed. It was found that the formation of spinels may be related to the spallation of $Zr0_2$-7wt.% $Y_20_3$ during isothermal oxidation.

• Journal of the Korean Magnetics Society
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• v.16 no.2
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• pp.111-114
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• 2006

We investigated the magnetism and electronic structures for the layered structures consisting of (110) layers of zinc-blende CrAs and MnAs. We calculated the electronic structures for $(CrAs)_3(MnAs)_3(110)$ superlattice consisted of alternating three layers of CrAs(110) and MnAs(110) by the full-potential linearized augmented plane wave (FLAPW) method. The calculated magnetic moment of Cr in interface layer ($3.07\;\mu_B$) was slightly larger than that of Cr atom in center layer ($3.06\;\mu_B$), while that of interface Mn atom ($3.74\;\mu_B$) was slightly smaller than the value of Mn atom in center layer ($3.76\;\mu_B$). The electronic structure and half-metallicity in this superlattice were discussed using the calculated density of states.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1982-1984
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• 1996

In this paper, we have evaluated the physical characteristicsof the Pt/Cr bilayer, fabricated the micro hot plate by using the Pt/Cr bilayer and E-beam evaporated oxide as a passivation layer, and simulated the thermal distribution by using the commercial software FIDAP. From the researches the sheet resistance of Pt/Cr bilayer didn't be affected by the Cr layer thickness. This results was considered due to the Cr-oxide resided at the interface between Pt and Cr layer. After manufacturing the hot plate, we measured its temperature by type k thermo-couple and I.R. thermo-vision system. In those experiments, the emission coefficient( ${\varepsilon}$ ) of the E-beam evaporated oxide was 0.5 and the temperature of centural region was reached about $305\;^{\circ}C$ at 1.3 watts. The temperature simulation obtained by FIDAP commercial package stewed that the temperature of centural region was about $311\;^{\circ}C$ after 5 sec.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.9
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• pp.2323-2340
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• 2012

Recent advances in cognitive radio technology have drawn immense attention to higher layer protocols above medium access control, such as transmission control protocol (TCP). Most proposals to improve the TCP performance in cognitive radio (CR) networks have assumed that either all nodes are in CR networks or the TCP sender side is in CR links. In those proposals, lower layer information such as the CR link status could be easily exploited to adjust the congestion window and improve throughput. In this paper, we consider a TCP network in which the TCP sender is located remotely over the Internet while the TCP receiver is connected by a CR link. This topology is more realistic than the earlier proposals, but the lower layer information cannot be exploited. Under this assumption, we propose an enhanced TCP protocol for CR networks called TCP for cognitive radio (TCP-CR) to improve the existing TCP by (1) detection of primary user (PU) interference by a remote sender without support from lower layers, (2) delayed congestion control (DCC) based on PU detection when the retransmission timeout (RTO) expires, and (3) exploitation of two separate scales of the congestion window adapted for PU activity. Performance evaluation demonstrated that the proposed TCP-CR achieves up to 255% improvement of the end-to-end throughput. Furthermore, we verified that the proposed TCP does not deteriorate the fairness of existing TCP flows and does not cause congestions.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.53-54
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• 2013

Nano-multilayered CrAlSiN films consisting of crystalline CrN nanolayers and amorphous AlSiN nanolayers were deposited by cathodic arc plasma deposition. Their oxidation characteristics were studied between 600 and $1000^{\circ}C$ for up to 70 h in air. During their oxidation, the amorphous AlSiN nanolayers crystallized. The formed oxides consisted primarily of $Cr_2O_3$, ${\alpha}-Al_2O_3$, $SiO_2$. The outer $Al_2O_3$ layer formed by outward diffusion of Al ions. Simultaneously, an inner ($Al_2O_3$, $Cr_2O_3$)-mixed layer formed by the inward diffusion of oxygen ions. $SiO_2$ was present mainly in the lower part of the oxide layer due to its immobility. The CrAlSiN films displayed good oxidation resistance, owing to the formation of oxide crystallites of $Cr_2O_3$, ${\alpha}-Al_2O_3$, and amorphous $SiO_2$.

• Journal of Powder Materials
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• v.22 no.6
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• pp.408-412
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• 2015

This study attempts to manufacture a Ni-Cr-Al-Y coating layer using a kinetic spray process and investigates the microstructure and physical properties of the manufactured layer. The Ni-22Cr-10Al-1Y (wt.%) composition powder is used, and it has a spherical shape with an average diameter of $23.7{\mu}m$. Cu plate is used as the substrate. Optical microscope, X-ray diffraction, scanning electron microscope and Vickers hardness test are carried out to characterize the macroscopic properties of the coating layer. Furthermore, the coating layer underwent vacuum heat treatment at temperatures of $400^{\circ}C$ and $600^{\circ}C$ for 1 hour to check the effect of heat treatment temperature on the properties. The manufactured coating layer is 1.5 mm thick, and featured identical phases to those found in the powder. The porosity of the coating layer is measured at 2.99%, and the hardness is obtained at $490.57H_v$. The layer shows reduced porosity as heat treatment temperature increased, and hardness is reduced at $400^{\circ}C$ but shows a slight increase at $600^{\circ}C$. Based on the findings described above, this study also discusses possible manufacturing methods for a Ni-Cr-Al-Y coating layer using the kinetic spray process.

• Journal of the Korean Magnetics Society
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• v.9 no.5
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• pp.256-262
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• 1999

Sputter deposited CoCr(Mo)/Si film were studied with emphasis on the correlation between magnetic properties and crystallographic orientation. The perpendicular coercivities of CoCr films decreased with Si underlayer thickness, whereas those of CoCrMo films increased with Si underlayer thickness. It has been explained that additions of the larger atomic radius Mo atoms in CoCr films impedes crystal growth resulting in a decrease in grain size, thus this small grain size may induce high perpendicular coercivity. The c-axis alignment of CoCrMo film was improved due to addition of 2at.%Mo. It means CoCrMo layer grow self-epitaxial directly from orientation and structure of Si underlayer when the main layer grow on underlayer.