• 전자공학회논문지A
• /
• 제33A권12호
• /
• pp.47-52
• /
• 1996

Cl-based gas chemistry is generally used to etching for al alloy metallization. After the etching of Al alloy with Cl-based gas plasma, residual chlorine on Al alloy reacts with H$_{2}$O due to air exposure and results in Al corrosion. In this study, the corrosion phenomena of Al wer examined with XPS(X-ray photoelectron spectroscopy) and SEM (scanning electorn microscopy). It was confirmed that chlorine mainly existed at the grian boundary of Al alloy after plasma etching of Al alloy with cl-based gas chemistry and Al corrosion was largely generated at the grain boundary of Al alloy. And residual chlorine was passivated by sulfur and fluorine which were generated by SF$_{6}$ plasma. These effects of passivation reduced the Al corrosion due to air exposure.

• Journal of the Optical Society of Korea
• /
• 제11권3호
• /
• pp.133-137
• /
• 2007

We compare electroabsorption modulators (EAMs) with multiple quantum wells (MQWs) based on InGaAs(P)/InP and InGa(Al)As/InAlAs material systems. We carefully choose the quantum-well structures so that the structures based on different material systems have similar band-offset energies and excition-peak wavelengths. Assuming the same light wavelength of $1.55{\mu}m$, we show the transfer functions of EAMs with each quantum-well structure and calculate the escape times of photogenerated charge carriers. As the heavy-hole escape time of the quantum well based on InGaAs(P)/InP is much longer than those of photogenerated charge carriers of InGa(Al)As/InAlAs, the EAM based on the InGa(Al)As/InAlAs material seems to be more suitable for high-optical-power operation.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2005년도 춘계학술대회 논문집
• /
• pp.176-179
• /
• 2005

Spray casting of hypereutectic Al-Si based alloy has been reported to provide distinct advantages over ingot metallurgy (IM) or rapid solidification/powder metallurgy (RS/PM) process in terms of microstructure refinement. Hypereutectic Al-Si based alloys have been regarded attractive for automotive and aerospace application, due to high specific strength, good wear resistance, low coefficient of thermal expansion, high thermal stability, and good creep resistance. In this study, hypereutectic Al-25Si-2.0Cu-1.0Mg alloy was prepared by OSPREY spray casting process. High temperature deformation behavior of the hypereutectic Al-Si based alloy has been investigated by applying the internal variable theory proposed by Chang et al. The change of strain rate sensitivity and Creep transition were analyzed by using the load relaxation test and constant creep test.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1996년도 추계학술대회 논문집
• /
• pp.252-255
• /
• 1996

Cl-based gas chemistry is generally used to etching for Al alloy metallization. After the etching of Al alloy with Cl-based gas plasma, residual chlorine on Al alloy reacts with $H_2O$ due to air exposure and results in Al corrosion. In this study, the corrosion Phenomena of Al were examined with XPS(X-ray photoelectron spectroscopy) and SEF(Scanning electron microscopy). It was confirmed that chlorine mainly existed at the grain boundary of Al alloy after plasma etching of Al alloy with Cl-based gas chemistry and Al corrosion was largely generated at the grain boundary of Al a1loy. And residual chlorine was passivated by sulfur and fluorine which were generated by SF$_{6}$ plasma. These effects of passivation reduced the Al corrosion due to air exposure.e.

• 디지털산업정보학회논문지
• /
• 제14권4호
• /
• pp.125-134
• /
• 2018

Lamport firstly suggested password base authentication scheme and then, similar authentication schemes have been studied. Due to the development of Internet network technology, remote user authentication using smart card has been studied. Li et al. analyzed authentication scheme of Chen et al. and then, Li et al. found out the security weakness of Chen et al.'s scheme such forward secrecy and the wrong password login problem, and proposed an a new smart card based user password authentication scheme. But Liu et al. found out that Li et al.'s scheme still had security problems such an insider attack and man-in-the-middle attack and then Liu et al. proposed an efficient and secure smart card based password authentication scheme. This paper analyzed Liu et al.'s authentication and found out that Liu et al.'s authentication has security weakness such as no perfect forward secrecy, off-line password guessing attack, smart-card loss attack, and no anonymity. And then, this paper proposed security enhanced efficient smart card based password authentication scheme using fuzzy extraction technology.

• Tribology and Lubricants
• /
• 제28권2호
• /
• pp.56-61
• /
• 2012

In order to investigate the possibility of Ni-Al based intermetallics coating onto aluminum substrate, the coating process for induction heating has been evaluated by microscopically analyzing the intermetallic layers coated at temperatures lower than the melting temperature of aluminum. The coating layers were divided into two parts with different microstructure along the depth. Hard $NiAl_3$ layer was found at lower parts of the coatings near the interface with aluminum substrate. This layer was formed by the diffusion of aluminum atoms from the substrate into the coating layer across the interface during the induction heating. Meanwhile, at the upper parts of the coating near the surface, a large amount of un-reacted Ni was still remained and surrounded by several Ni-Al based intermetallic compounds, such as $Ni_3Al$, NiAl and $Ni_2Al_3$ formed by the lattice diffusion.

• 한국세라믹학회지
• /
• 제22권6호
• /
• pp.42-52
• /
• 1985

Several $Al_2O_3$-based polycrystalline which had different dopant ratio in the range of 0.5mol% were prepared by doping pure $Cr_2O_3$ $HfO_2$. Single crystalline which had same composition with above polycrystalline were made by means of floating zone method. This study examined the role of each dopant for enhancing the mechanical properties of $Al_2O_3$-based Ceramics. Optical micrographs $({ imes}200)$ of $Al_2O_3-Cr_2O_3$ single crystal showing not only radial crack (rc) on the specimen surface but median crack(mc) and lateral crack(lc) under surface at the edge of indentation mark. Fracture toughness of Al2O3-based Ceramics was increased with $ZrO_2$ content. Alloying effect of $Cr_2O_3$ contributed to the hardness of $Al_2O_3$ based ceramics.

• 한국재료학회지
• /
• 제12권11호
• /
• pp.845-849
• /
• 2002

Alloys of $Fe_3$Al, $Fe_3$Al-6Cr, $Fe_3$Al-4Cr-1Mo, $Ni_3$Al, and $Ni_3$Al-2.8Cr were oxidized at $1000^{\circ}C$ in air, and the oxide scales formed were studied using XRD. SEM, EPMA, and TEM. The oxide scales that formed on $Fe_3$Al-based alloys consisted primarily of $\alpha$-$Al_2$$O_3$ containing a small amount of dissolved Fe and Cr ions, whereas those that formed on $Ni_3$Al-based alloys consisted primarily of $\alpha$-$Al_2$$O_3$, together with a small amount of $NiAl_2$$O_4$, NiO and dissolved Cr ions. For the entire alloys tested, nonadherent oxide scales formed, and voids were inevitably existed at the scale-matrix interface.

• 대한금속재료학회지
• /
• 제48권10호
• /
• pp.936-941
• /
• 2010

Al-Zn based alloys are the most common types of wrought Al alloys. Although Al-Zn alloys have high strength, they cannot be applied to a conventional casting process. In this study, Al-Zn-based alloys applicable to a die casting process were developed successfully. The developed Al-45 wt% Zn-based alloys showed a fine equiaxed grain structure and high strength. A fine equiaxed grain having an average size of $25{\mu}m$ was obtained by the die casting process. The UTS and elongation of the new alloy are 475 MPa and ~3.5%, respectively. In addition, we elucidate the effect of a Zn addition on variations in different mechanical properties and the microstructure characteristics of (Al96.3-xZnxCu3Si0.4Fe0.3) x=20, 30, 40, and 45 wt% alloys fabricated by a die casting process.

• IEIE Transactions on Smart Processing and Computing
• /
• 제2권5호
• /
• pp.297-301
• /
• 2013

Key agreement protocols allow multi-parties exchanging public information to create a common secret key that is known only to those entities over an insecure network. Since Joux first published the pairing-based one round tripartite key agreement protocol, many authenticated protocols have been proposed. Unfortunately, many of them have been broken while others have been shown to be deficient in some desirable security attributes. In 2004, Cheng et al. presented two protocols aimed at strengthening Shim's certificate-based and Zhang et al.'s tripartite identity-based protocols. This paper reports that 1) In Cheng et al.'s identity-based protocol, an adversary can extract long-term private keys of all the parties involved; and 2) Cheng et al.'s certification-based protocol is weak against key integrity attacks. This paper suggests possible remedies for the security flaws in both protocols and then presents a modified Cheng et al.'s identity-based, one-round tripartite protocol that is more secure than the original protocol.