• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.1
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• pp.9-16
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• 2011

Primary water stress corrosion cracking (PWSCC) has been found in the weld region of the nuclear power plant. Welding can produce tensile residual stress. Tensile residual stress contributes to the initiation and growth of PWSCC. It is important to estimate weld residual stress accurately to predict or prevent the initiation and growth of PWSCC. This paper shows the results of finite element analysis and measurement experiment for weld residual stress. For the study, four kinds of specimen were fabricated with the materials used in the nuclear power plant. Residual stresses were measured by four kinds of methods of hole drilling, x-ray diffraction, instrumented indentation and sectioning. Through the study, numerical analysis and measurement results were compared and the characteristics of each measurement technique were observed.

• Journal of the Korean Ceramic Society
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• v.43 no.8 s.291
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• pp.492-497
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• 2006

SiC coating has been introduced as protective layer in TRISO nuclear fuel particle of High Temperature Gas cooled Reactor (HTGR) due to excellent mechanical stability at high temperature. In order to inhibit the failure of the TRISO particles, it is important to evaluate the fracture strength of the SiC coating layer. ]n present work, thin silicon carbide coating was fabricated using chemical vapor deposition process with different microstructures and thicknesses. Processing condition and surface status of substrate.affect on the microstructure of SiC coating layer. Sphere indentation method on trilayer configuration was conducted to measure the fracture strength of the SiC film. The fracture strength of SiC film with different microstructure and thickness were characterized by trilayer strength measurement method nanoindentation technique was also used to characterize the elastic modulus and th ε hardness of the SiC film. Relationships between microstructure and mechanical properties of CVD SiC thin film were discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.8
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• pp.514-519
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• 2017

TiN (titanium nitride) films were prepared using the RF magnetron sputtering technique. The films were deposited by pure $N_2$ plasma sputtering. Their mechanical properties, such as nano-indentation hardness, friction coefficient, and surface wettability, have been investigated. X-ray diffraction (XRD) studies revealed that the orientation of $TiN_X$ films changed towards the (111) orientation with decreasing working pressure due to a strong compressive stress during deposition. The strongest TiN (111) orientation was found when the film was deposited at a working pressure of 1 Pa. This film showed the largest hardness (16 GPa) and smallest friction coefficient (0.17) among the studied samples. Moreover, this film was found to be accompanied by a water-repellent surface with water contact angle more than $100^{\circ}$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05a
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• pp.70-73
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• 2004

The packaging of the integrated circuits requires knowledge of ceramics and metals to accommodate the fabrication of modules that are used to construct subsystems and entire systems from extremely small components. Composite ceramics (Al$_2$O$_3$-SiO$_2$) were tested for substrates. A stress analysis was conducted for a linear work-hardening metal cylinder embedded in an infinite ceramic matrix. The bond between the metal and ceramic was established at high temperature and stresses developed during cooling to room temperature. The calculations showed that the stresses depend on the mismatch in thermal expansion, the elastic properties, and the yield strength and work hardening rate of the metal. Experimental measurements of the surface stresses have also been made on a Cu/Al$_2$O$_3$-SiO$_2$ceramic system, using an indentation technique. A comparison revealed that the calculated stresses were appreciably larger than the measured surface stresses, indicating an important difference between the bulk and surface residual stresses. However, it was also shown that porosity in the metal could plastically expand and permit substantial dilatational relaxation of the residual stresses. Conversely it was noted that pore clusters were capable of initiating ductile rupture, by means of a plastic instability, in the presence of appreciable tri-axiality. The role of ceramics for packaging of microelectronics will continue to be extremely challenging.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.308-312
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• 2003

The packaging of the integrated circuits requires knowledge of ceramics and metals to accommodate the fabrication of modules that are used to construct subsystems and entire systems from extremely small components. Composite ceramics ($Al_2O_3-SiO_2$) were tested for substrates. A stress analysis was conducted for a linear work-hardening metal cylinder embedded in an infinite ceramic matrix. The bond between the metal and ceramic was established at high temperature and stresses developed during cooling to room temperature. The calculations showed that the stresses depend on the mismatch in thermal expansion, the elastic properties, and the yield strength and work hardening rate of the metal. Experimental measurements of the surface stresses have also been made on a $Cu/Al_2O_3-SiO_2$ ceramic system, using an indentation technique. A comparison revealed that the calculated stresses were appreciably larger than the measured surface stresses, indicating an important difference between the bulk and surface residual stresses. However, it was also shown that porosity in the metal could plastically expand and permit substantial dilatational relaxation of the residual stresses. Conversely it was noted that pore clusters were capable of initiating ductile rupture, by means of a plastic instability, in the presence of appreciable tri-axiality. The role of ceramics for packaging of microelectronics will continue to be extremely challenging.

• Korean Journal of Metals and Materials
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• v.46 no.7
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• pp.464-470
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• 2008

Metallic nanostructures have great potential for bio-chemical sensor applications due to the excitation of localized surface plasmon and its sensitive response to environmental change. Unlike the commonly explored absorption-based sensing, the optical scattering provides single particle detection scheme. For the localized surface plasmon resonance spectroscopy, the metallic nanostructures with controlled shape and size have been usually fabricated on adhesion-layer pre-coated transparent glass substrates. In this study, we calculated the optical scattering properties of plasmonic Au nanodisc using a discrete dipole approximation method and analyzed the effect of adhesion layer on them. Our result also indicates that there is a trade-off between the surface plasmon damping and the capability of supporting nanostructures in determining the optimal thickness of adhesion layer. Marginal thickness of Ti adhesion layer for supporting Au nanostructures fabricated on a silica glass substrate was experimentally analyzed by an adhesion strength test using a nano-indentation technique.

• Restorative Dentistry and Endodontics
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• v.46 no.1
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• pp.12.1-12.9
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• 2021

Objectives: The present study aims to compare the obturation quality of 2 confluence confirmation techniques in artificial maxillary first premolars showing Vertucci type II root canal configuration. Materials and Methods: Thirty artificial maxillary premolars having Vertucci type II root canal configuration were made. They were divided into 3 groups according to the confluence confirmation technique as follows. Gutta-percha indentation (GPI) group (confluence confirmation using a gutta-percha cone and a K file); electronic apex locator (EAL) group (confluence confirmation using K files and EAL); and no confluence detection (NCD) group. In the GPI group and the EAL group, shaping and obturation were performed with the modified working length (WL). In the NCD group, shaping was performed without WL adjustment and obturation was carried out with an adjusted master cone. Micro-computed tomography was used before preparation and after obturation to calculate the percentage of gutta-percha occupied volume (%GPv) and the volume increase in the apical 4 mm. Data were analyzed using 1-way analysis of variance and post hoc Tukey's test. Results: Statistically significant difference was not found in terms of the %GPv from the apex to apical 4 mm. However, the NCD group showed a statistically significant volume increase compared with the EAL group (p < 0.05). Conclusions: In terms of gutta-percha occupied volume, no significant difference was observed among the 3 groups. Confluence confirmation using an EAL in teeth with Vertucci type II configuration showed less volume increase during canal shaping compared with no confluence confirmation.

• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.1-8
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• 2004

The microstructural features and mechanical behavior of directionally solidified $(Y_2O_3)ZrO_2/Al_2O_3$ eutectic fibers after extended beat treatment in oxidizing environment were investigated. The fiber was grown continuously by an Edge-defined Film-fed Growth (EFG) technique. The microstructure was characterized using X-Ray Diffraction (XRD) and Scanning Electron Microscopy(SEM). The microstructure of the fiber in the as-fabricated state consists of highly oriented colonv and fine lamellar microstructure along the fiber axis. Tensile strength of the $(Y_2O_3)ZrO_2/Al_2O_3$ eutectic fiber remained unchanged with heat treatment at temperatures between $1200^{\circ}C$ and $1500^{\circ}C$ up to 300h. The weibulls modulus remained fairly constant after extended thermal exposure. The fracture toughness and crack propagation behavior were investigated. The fracture toughness ($K_{1C}$) of the $(Y_2O_3)ZrO_2/Al_2O_3$ eutectic fiber in the as-fabricated state were measured to be 3.6 ${\pm}$ 0.5 MPa${\cdot}m^{1/2}$ by an indentation technique and 2.2 ${\pm}$ 0.2 MPa${\cdot}m^{1/2}$ by assuming elliptical flaw of a semi-infinite solid, respectively. The $(Y_2O_3)ZrO_2/Al_2O_3$ eutectic fiber showed a radial (Palmqvist) crack type and exhibited an orthotropic crack growth behavior under 100 g load.

• Journal of the Korean Vacuum Society
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• v.17 no.6
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• pp.518-522
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• 2008

The miniaturization of device size and multilevel interlayers have been developed by ULSI circuit devices. These submicron processes cause serious problems in conventional metallization due to the solubility of silicon and metal at the interface, such as an increasing contact resistance in the contact hole and interdiffusion between metal and silicon. Therefore it is necessary to implement a barrier layer between Si and metal. Thus, the size of multilevel interconnection of ULSI devices is critical metallization schemes, and it is necessary reduce the RC time delay for device speed performance. So it is tendency to study the Cu metallization for interconnect of semiconductor processes. However, at the submicron process the interaction between Si and Cu is so strong and detrimental to the electrical performance of Si even at temperatures below $200^{\circ}C$. Thus, we suggest the tungsten-carbon-nitrogen (W-C-N) thin film for Cu diffusion barrier characterized by nano scale indentation system. Nano-indentation system was proposed as an in-situ and nanometer-order local stress analysis technique.

• Journal of Dental Rehabilitation and Applied Science
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• v.17 no.3
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• pp.199-204
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• 2001

This study was to investigate the reused possibility of zirconia reinforced glass-ceramic(IPS Empress Cosmo ceramic) with sprue button in the flexure strength and fracture toughness. 40 disk-shaped ceramic specimens (20 specimens: as-pressed material; 20 specimens: reused material) with approximately 1.7 mm thickness and 15 mm diameter were prepared by "lost wax" technique. The remnants(sprue buttons) were used for repressing. The surface treatments for the discs were gradually abraded with 320, 800, 1200, and 2000 grit SiC sandpaper. The specimens were evaluated their flexure strength with the biaxial flexure jig(ball-on-three balls) and their fracture toughness with Vickers Indentation-microfracture test. The Weibull moduli were calculated for biaxial flexural strength. The mean flexure strength and fracture toughness of each group were $122.2{\pm}18.3MPa$, $1.00{\pm}0.09MPa{\cdot}m^{0.5}$ (as-pressed ceramics), and $122.2{\pm}20.3MPa$, $1.01{\pm}0.10MPa{\cdot}m^{0.5}$ (reused ceramics). There were no significant differences in the strength and the fracture toughness between the as-pressed and the reused IPS Empress Cosmo ceramic (P>0.05). This implied zirconia reinforced glass-ceramic(IPS Empress Cosmo ceramic) could be used one more time by reusing of sprue button in the flexure strength and fracture toughness.