• Korean Journal of Materials Research
• /
• v.12 no.2
• /
• pp.117-120
• /
• 2002

We investigated the possibility of direct bonding of the Si ∥SiO$_2$/Si$_3$N$_4$∥Si wafers for Oxide-Nitride-Oxide(ONO) gate oxide applications. 10cm-diameter 2000$\AA$-thick thermal oxide/Si(100) and 500$\AA$-Si$_3$N$_4$LPCVD/Si (100) wafers were prepared, and wet cleaned to activate the surface as hydrophilic and hydrophobic states, respectively. Cleaned wafers were premated wish facing the mirror planes by a specially designed aligner in class-100 clean room immediately. Premated wafer pairs were annealed by an electric furnace at the temperatures of 400, 600, 800, 1000, and 120$0^{\circ}C$ for 2hours, respectively. Direct bonded wafer pairs were characterized the bond area with a infrared(IR) analyzer, and measured the bonding interface energy by a razor blade crack opening method. We confirmed that the bond interface energy became 2,344mJ/$\m^2$ when annealing temperature reached 100$0^{\circ}C$, which were comparable with the interface energy of homeogenous wafer pairs of Si/Si.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.5
• /
• pp.483-487
• /
• 2014

In this study, joining methods with SiC powder as the joining adhesives were studied in order to avoid the residual stresses coming from CTE (Coefficient of Thermal Expansion) mismatch between substrate and joining layer. The shear strength and microstructure of joined material between SiC substrates are investigated. The commercial Hexoloy-SA (Saint-Gobain Ceramics, USA) used in this work as substrate material. The fine ${\beta}$-SiC nano-powder which the average particle size is below 30 nm, $Al_2O_3$, $Y_2O_3$, and $SiO_2$ were used as joining adhesives. The specimens were joined with 20MPa and $1400-1900^{\circ}C$ by hot pressing in argon atmosphere. The shear test was performed to investigate the bonding strength. The cross-section of the joint was characterized by using an optical microscope and scanning electron microscopy (SEM).

• Composites Research
• /
• v.23 no.6
• /
• pp.32-38
• /
• 2010

The effect of the atmospheric pressure plasma(APP) treatments is experimentally investigated to ascertain the optimum condition to yield the best adhesive properties between a polyamide woven fabric and acrylonitrile butadiene rubber(NBR). For the atmospheric pressure flame plasma(APFP) treatment, the optimum number of treatment at given conditions is 2 times. The thermal deformation of the fabric is more serious with increasing the number of APFP treatment. The adhesive strength of the case with APFP treated fabric is increased about 35% when compare to the case with non-APFP treated one for the interface(bonding agent one or two coatings). When the surface is coated twice with the bonding agent, the adhesive energy with APFP treated fabric is increased about 4 times. It was found that the surface modification of polyamide woven fabric by APFP treatment is a fast, economic and applicable method to improve the adhesive properties between woven fabric and rubber when compared to other APP treatments.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.23 no.3
• /
• pp.99-108
• /
• 2021

The present study examines the overall manufacturing status of local wetsuit makers, problems in the manufacturing process, and future research tasks. The study revealed that most manufacturers use neoprene fabric of varying thickness, depending on the body part. Normally, 3 mm-thick fabric is utilized for high-activity body parts and 5 mm-thick fabric is used for high-activity areas requiring thermal insulation. In terms of the manufacturing method, the tools and manufacturing processes used by companies were found to be similar. However, because of the nature of wetsuits requiring a more complicated manufacturing method than that of general clothing, there were some differences in the manufacturing method processes from company to company, such as bonding and ease treatments. According to wetsuit manufacturers, they make incisions in consideration of the body's curvature and the overall shape and design of the wetsuit when developing patterns. For example, most answered that they preform the wrist and ankle parts, where the body's curvature is obvious. On the question regarding the "difficult manufacturing process", the most frequent response was the "bonding" process. Most manufacturers were found to focus on designs that can improve mobility and clothing fit, and commonly experienced low-order quantity as an operational difficulty. As for the question on the wetsuit-related technology needed in the future, the "development of various designs" was the most frequent answer, followed by the "development of lightweight and diverse materials".

• Composites Research
• /
• v.20 no.3
• /
• pp.37-42
• /
• 2007

Tensile residual stress is occurred by difference of coefficients of thermal expansion between fiber and matrix is one of the serious problems in metal matrix composite(MMC). TiNi alloy fiber was used to solve the problem of the tensile residual stress as the reinforced material. TiNi alloy fiber improves the tensile strength of composite with occurring of compressive residual stress in the matrix by its shape memory effect. A hot press method was used to create the optimal fabrication condition for a Shape Memory Alloy(SMA) composite. The bonding effect of the matrix and the reinforcement within the SMA composite by the hot press method was strengthened by cold rolling. In addition, acoustic emission technique was used to quantify the microscopic damage behavior of cold rolled TiNi/A16061 shape memory alloy composite at low temperature. The damage degree for the specimen that underwent thermal shock cycles was also discussed.

• Journal of Korea Foundry Society
• /
• v.12 no.4
• /
• pp.317-325
• /
• 1992

Diamond is the hardest material known to humans, also possesses the highest thermal conductivity and a very low thermal expansion coefficient. Therefore, these properties of diamond make them logical choices for many difficult grinding application. Bonding material is a very important factor to performance of a grinding wheel. Grinding glass constitutes one of the major application areas of diamond grinding wheels, and Cu-Sn tin bronze matrix is widely used as a metal bond of diamond wheel in grinding glass but these studies are rarely reported. The bronze test pieces excluding diamond are sintered by the method of hot sizing respectively at $600^{\circ}C$, $650^{\circ}C$, $700^{\circ}C$, with a composition(Cu-10wt%Sn) on ${\alpha}$ phase and two compositions(Cu-20wt%Sn and Cu-23wt%Sn) on ${\alpha}+{\beta}$ phase. The rupture strength of Cu-10wt%Sn is highest. The bronze bonded diamond wheels are manufactured by same conditions as the bronze test pieces. The results of grinding ratio of wheels are highest in case of Cu-10wt%Sn bonded wheel sintered at $650^{\circ}C$ and grinding power is highest in same composition sintered at $700^{\circ}C$.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.9
• /
• pp.3255-3260
• /
• 2011

Two novel binuclear metal-organic coordination complexes $[Cd_2(L)_2(bpy)_2(H_2O)_2]{\cdot}6H_2O$ (1), $[Cd_2(L)_2(phen)_2-(H_2O)_2]{\cdot}2H_2O$ (2) (where L = 2-methylquinoline-3,4-dicarboxylate dianion, bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline) have been synthesized under hydrothermal conditions and characterized by single crystal Xray diffraction, spectral method (IR), elemental analysis and thermal gravimetric analysis (TGA). Both 1 and 2 consist of two Cd(II) atoms bridged by two monoatomic bridging carboxylate groups from two L ligands, and the second carboxylate group of each L is monodentately coordinated to Cd(II), creating a sevenmembered chelating ring. The coordination at each metal nucleus is completed by a water molecule and a chelating bidentate molecule. The 3D structures of the complexes are stabilized by ${\pi}-{\pi}$ stacking interactions and hydrogen-bonds.

• The Journal of the Korean dental association
• /
• v.54 no.12
• /
• pp.985-995
• /
• 2016

Titanium (Ti) has been widely used for dental implant due to great biocompatibility and bonding ability against natural alveolar bone. A lot of titanium surface modification has been introduced in dentistry and, among them, methods to introduce micro/nano-roughened surface were considered as clinically approved strategy for accelerating osseointegration of Ti dental implant. To have synergetic effect with topography oriented favors in cell attachment, chair-side surface treatment with reproducibility of micro/nano-topography is introduced as next strategy to further enhance cellular functionalities. Extensive research has been investigated to study the potential of micro/nano-topography preserved chair-side surface treatment for Ti dental implant. This review will discuss ultraviolet, low level of laser therapy and non-thermal atmospheric pressure plasma on Ti dental implant with micro/nano-topography as next generation of surface treatment due to its abilities to induce super-hydrophilicity or biofunctionality without change of topographical cues.

• Macromolecular Research
• /
• v.12 no.5
• /
• pp.534-539
• /
• 2004

Two biopolymers, silk fibroin (SF) and chitosan, were conjugated by tyrosinase (EC 1.14.18.1), a polyphenolic oxidase, to improve their physicochemical properties, such as their thermal properties and morphological stabilities in organic solvents. The crosslinking between SF and chitosan took place mainly through Michael addition reactions. A main reaction between the amino groups in chitosan and o-quinone, the oxidation product of the tyrosyl residue in SF, was confirmed by UV spectroscopy. Measurements of viscosity and light scattering indicated that the crosslinked SF/chitosan conjugate was compact: it had a smaller particle size because of tight bonding forces between the SF and chitosan molecular chains. Thermal decomposition of SF/chitosan conjugates crosslinked by tyrosinase occurred at higher temperatures. The adhesiveness of the SF/chitosan conjugates decreased steadily as the crosslinking reaction progressed. We propose that this new crosslinking method be used for the preparation of silk fibroin/chitosan conjugates using tyrosinase. We expect that SF/chitosan conjugates crosslinked by tyrosinase can be used preferentially in biomedical applications because of its unique properties and non-toxicity.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.3
• /
• pp.939-942
• /
• 2011

Conductive carbon films were prepared at room temperature by unbalanced magnetron sputtering (UBMS) on silicon substrates using argon (Ar) gas, and the effects of post-annealing temperature on the structural, tribological, and electrical properties of carbon films were investigated. Films were annealed at temperatures ranging from $400^{\circ}C$ to $700^{\circ}C$ in increments of $100^{\circ}C$ using a rapid thermal annealing method by vacuum furnace in vacuum ambient. The increase of annealing temperature contributed to the increase of the ordering and formation of aromatic rings in the carbon film. Consequently, with increasing annealing temperature the tribological properties of sputtered carbon films are deteriorated while the resistivity of carbon films significantly decreased from $4.5{\times}10^{-3}$ to $1.0{\times}10^{-6}\;{\Omega}-cm$ and carrier concentration as well as mobility increased, respectively. This behavior can be explained by the increase of sp2 bonding fraction and ordering $sp^2$ clusters in the carbon networks caused by increasing annealing temperature.