• Journal of the Korean institute of surface engineering
• /
• v.30 no.1
• /
• pp.23-32
• /
• 1997

The electrolytic boronizing on carbon steels in the mixture of $Na_2B_4O_7$ and NaCl was conducted at 750~$950^{\circ}C$ for 1~6 hours under 0.5A/$\textrm{cm}^2$ current density. The micorostructrure and microheredness of boronized layer was also studien. The effect of the additive such as $CaCl_2$ or NaOH on the formation of boronized layer was also investigated. The boronized layer were composed of two sublayers, i.e., FeB and $Fe_2B$ , which have tooth structure. the average layer thinknesses of the low carbon steel and SM45C boronized at $900^{\circ}C$ for 4hours were 153 and 138 $\mu\textrm{m}$, respectively. The thickness of the twosublayers was significantly increased with increasing boronizing temperature. To obtain a single $Fe_2B$ layer without FeB sublayer, the boronized materials ware homegenized at $950^{\circ}C$ for 4 hours. It was fount that the single layer with a microhardness Hv$\thickapprox$ 1120 -1250 was formed. The calculated activation energies for formation of boronized layer on the low carbon steel and SM45C were 18.7 and 12.6 Kcal/mol, respectively.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1998.10a
• /
• pp.251-257
• /
• 1998

Spherical space frame structure with triangular network pattern, which has the various characteristics for the mechanic property, a funtional property, an aesthetic property and so on, has often been used as one of the most efficient space structures. It is expected that this type will be used widely in large-span structural roofs. But because this structure is made of network by combination of line elements there me many nodes therefore, the structure behavior is very complicated and there can be an overall collapse of structure by buckling phenomenon if the external force reaches a limitation. This kind of buckling is due to geometric shape, network pattern, the number of layer and so on, of structure. Therefore spherical space frame with triangle network pattern have attracted many designers and researchers attention all over the world. The number of layer of space frame is divided in to the simgle, double, multi layer. That is important element which is considered deeply in the beginning of structural design. The buckling characteristics of single-layer model and double-layer model for the spherical space frame structure with triangular network pattern are evaluated and the buckling loads of these types are compared with investigation their structural efficiency in this study.

• Proceedings of the KIEE Conference
• /
• 2006.10a
• /
• pp.119-120
• /
• 2006

The impedance spectroscopy is one of the effective ways to understand the electrical properties of organic light emitting diodes. The frequency-dependant properties of small molecule based OLEDs have been studied. The equivalent circuit of single-layer device is composed of contact resistance ($R_c$), bulk resistance ($R_p$) and bulk capacitance ($C_p$). The equivalent circuit of double layer device is composed of two parallel circuits connected in series, each of which is a parallel resistor and a capacitor. We have fabricated a double layer device indium-rio-oxide (ITO, anode), N,NV -diphenyl- N,NV -bis(3-methylphenyI)-1,1V -diphenyl-4,4V-diamine (TPD, hole-transporting layer), tris-(8-hydroxyquinoline) aluminum (Alq3, emitting layer), and aluminum (AI, cathode) and two single layer devices ([TO/ Alq3/ AI, ITO/TPD/AI).

• Tribology and Lubricants
• /
• v.25 no.1
• /
• pp.7-12
• /
• 2009

Coating brittle intermetallic compounds on metal can enlarge the range of their use. It is found that intermetallic compound coating layers made by only combustion synthesis in an electric furnace have porous multi-phase structures containing several intermediate phases, even though the coating layers show good wear resistance. In this study, dense $Ni_{3}Al$ single phase layer corresponding to the initial composition of the mixed powder is coated on two different ferrous materials by the diffusing treatment after combustion synthesis. After- ward, sliding wear behaviors of the coating layer are evaluated in comparison with that of the coating layer with porous multi-phase structure made by only combustion synthesis. As a result, the wear properties of the coating layer composed of dense $Ni_{3}Al$ single phase are considerably improved at the range of low sliding speed com- pared with that of the coating layer with porous multi-phase structure, particularly in the running-in wear region. This is attributed to the fact that wear of the coating layer is progressed by shearing as a sequence of adhesion, not by occurring of pitting on the worn surface due to having dense structure without pores.

• Journal of Ceramic Processing Research
• /
• v.13 no.spc1
• /
• pp.140-144
• /
• 2012

Ga-doped ZnO (GZO) was a limit of application on the photovoltaic devices such as CIGS, CdTe and DSSC requiring high process temperature, because it's electrical resistivity is unstable above 300 ℃ at atmosphere. Therefore, ZTO (zinc tin oxide) was introduced in order to improve permeability and thermal stability of GZO film. The resistivity of GZO (300 nm) single layer increased remarkably from 1.8 × 10-3Ωcm to 5.5 × 10-1Ωcm, when GZO was post-annealed at 400 ℃ in air atmosphere. In the case of the ZTO (150 nm)/GZO (150 nm) double layer, resistivity showed relatively small change from 3.1 × 10-3Ωcm (RT) to 1.2 × 10-2Ωcm (400 ℃), which showed good agreement with change of carrier density. This result means that ZTO upper layer act as a barrier for oxygen at high temperature. Also ZTO (150 nm)/GZO (150 nm) double layer showed lower WVTR compared to GZO (300 nm) single layer. Because ZTO has lower WVTR compared to GZO, ZTO thin film acts as a barrier by preventing oxygen and water molecules to penetrate on top of GZO thin film.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.04a
• /
• pp.127-130
• /
• 2003

We have carried out two-beam interference experiment to form holographic grating on amorphous $As_{40}Ge_{10}Se_{15}S_{35}$ single-laver, $MgF_{2}/As_{40}Ge_{10}Se_{15}S_{35}$ muliti-layer. In this study holographic grating formed using He-Ne laser(632.8nm) under different polarization state(intensity, phase polarization holography). The diffraction efficiency was obtained by first order intensity. The maximum diffraction efficiency of $As_{40}Ge_{10}Se_{15}S_{35}$ single-laver was 0.8% and The maximum diffraction efficiency of $MgF_{2}/As_{40}Ge_{10}Se_{15}S_{35}$ multi-layer(multi-layer I, multi-layer II) were 1.4% and 3.1%.

• Journal of the Korean institute of surface engineering
• /
• v.54 no.1
• /
• pp.30-36
• /
• 2021

In this study, double-layered anodizing films were formed on Al 5052 and Al 6061 alloys consecutively first in sulfuric acid and then in oxalic acid, and hardness, withstand voltage, surface roughness and acid resistance of the anodizing films were compared with single-layered anodizing films in sulfuric acid and oxalic acid electrolytes. Hardness of the double-layered anodizing film decreased with increasing ratio of inner layer to outer layer for both Al 5052 and Al 6061 alloys, suggesting that outer anodizing film formed in sulfuric acid electrolyte is damaged during the second anodizing in oxalic acid electrolyte. Withstand voltage of the double-layered anodizing films increased with increasing the thickness ratio of inner layer to outer layer. Surface roughness of the double-layered anodizing films were comparable with that of single-layered anodizing film formed in sulfuric acid but higher than that of single layer anodizing film formed in oxalic acid electrolyte. In acid resistance test, all of the double-layered and single-layered anodizing films showed good acid resistance more than 3 h without any visible gas evolution, which is attributable to sealing of pores. Based on the experimental results obtained in this work, it is possible to design a double-layered anodizing film with cost-effectiveness and improved physical and electrical properties by combining two consecutive anodizing processes of sulfuric acid anodizing and oxalic acid anodizing methods.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.3
• /
• pp.9-15
• /
• 2011

The microstrip reflectarray antenna is rapidly becoming an attractive alternative solution to the traditional parabolic reflector antenna. However, the bandwidth of the microstrip reflectarray using the single layer structure is very narrow. To obtain wide bandwidth characteristic, the microstrip reflectarray using the multi-layer structure has been used, but it has some disadvantages such as high cost and complicated design. In this paper, to obtain low cost and wide bandwidth, the microstrip reflectarray antenna composed of square patch with two U-slots using the single-layer structure is proposed. The proposed antenna demonstrate radiation efficiency closed to 55.5 % and 1 dB gain bandwidth over 14 % at 12.5 GHz.

• Journal of Environmental Science International
• /
• v.14 no.12
• /
• pp.1195-1201
• /
• 2005

In order to develop a dye coloring technology on Conchiolin layer in cultured pearls, appropriate dyes were selected, their solubilities in various solvents were studied, and adsorption and desorption experiments were performed. Solubilities of several basic dyes known to suitable for the pearl coloring, i.e., Rhodamine 6G(R6), Rhodamine B(RB) and Methylene Blue(MB), in several solvents (distilled water, methanol, ethanol, and acetone) were investigated. Among these dyes, R6 was chosen as a dye for single component adsorption and desorption experiment due to the relatively good solubility in various solvents tested. Solubilities of dyes were judged to be enough to color the pearls since dye concentrations in pearl coloring are, in general, not so high. The internal surface area of the pearl layer is believed to be directly related to the dye adsorption, the single-point internal surface area of the pearl layer measured at the nitrogen relative pressure of 0.3 was found to be $0.913m^2/g$, and the BET internal surface area, $1.01m^2/g$ The most probable diameters of micropores and macropores were found to be $40{\AA}$and $5000{\AA}$ respectively, from the pore size distribution data. Adsorption isotherm was well fitted to the Langmuir isotherm model, resulting in q=$\frac{1.62C}{1+1.09C^{.}}$

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.10 s.181
• /
• pp.2520-2528
• /
• 2000

Mechanical and physical properties of composite materials make a great difference due to their cure process condition. In order to clarify the effect of cure process condition on the microscopic damage behavior and failure mechanism of Carbon/Epoxy composites, three point bend test has been performed. For this purpose, two kinds of specimens with single adhesive and multiple adhesive layers were prepared. For single adhesive layer, four different types of specimen were used, that is, non-sanding, sanding, cocured, laminated specimens. Three different types of specimen were also used for the multiple adhesive layer, non-sanding, sanding, cocured specimens. Acoustic emission technique has also been employed to monitor the damage progresses associated with each micro-failure mechanism. The characteristics of AE parameters associated with micro-failure mechanism of each specimen were discussed.