• Proceedings of the Materials Research Society of Korea Conference
• /
• 2011.05a
• /
• pp.244.1-244.1
• /
• 2011

Memristors have been studied for many years due to better scalability than DRAMs and FLASH memories thus they are considered now as a strong candidate for future memories. To describe the electrical behavior of memristors, various memristor models have been developed. Especially, many kinds of window function have been used to express the non-linearity of memristors which are thought to cause different voltage-current relationships in memristors. In this paper, the previous memristor models with different window functions are compared and analyzed. This comparative study can be very useful in not only understanding the diversity in memristor's electrical behaviors but also developing memristor circuits. This work was financially supported by the SRC/ERC program of MOST/KOSEF (R11-2005-048-00000-0). The CAD tools were supported by the IC Design Education Center (IDEC), Korea.

• Journal of Welding and Joining
• /
• v.33 no.6
• /
• pp.42-48
• /
• 2015

Reduced activation ferritic/martensitic steels are recognized as the primary candidate structural materials for fusion blanket systems. Welding is an inevitable for breeding blanket for pressure tightness and radioisotope confinement. Especially, TIG welding was chosen for sealing because it has the largest gap allowance compared to the other welding methods, and its properties are controllable by feed wire and welding conditions. In this study, the low cycle fatigue test using two-type gage such as extensometer and strain gage was applied to the TIG welded joint of F82H steel, for evaluating fatigue damage accumulation behavior of the HAZs. As the result, the over-tempered HAZ have shown a higher fatigue damage accumulation compared with other materials at all the testing conditions.

• Nuclear Engineering and Technology
• /
• v.52 no.4
• /
• pp.856-862
• /
• 2020

Defect inspection system for industrial applications takes the important portion. Non-destructive inspection method has been significantly improved. Infrared thermography, as one of method for non-destructive inspection, can provide relatively precise data and quick inspection time. This study, it was performed to measure defect according to the measurement limit of the non-visible areas such as the back surface of the pipe using reflection plate using reflection plate based on Infrared thermography. The materials of the reflection plate were determined in consideration of the space limitation and the thermal characteristics, and defects were detected by the manufactured reflection plate. Detection of defect in non-visible area using the candidate materials for reflection plate was conducted.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2005.07b
• /
• pp.1245-1247
• /
• 2005

Glass frit was selected to be a $Bi_2O_3-RO-R_2O_3$ system as a sealing material to replace the current PbO system in PDP. Fillers such as a zircon, cordierite and ${\beta}-eucryptite$ were added for the control of thermal expansion coefficient (CTE), flowability and strength for sealing. At $450-500^{\circ}C$, reaction of frit and filler and interface were evaluated by a flow button test and SEM observation. The composite (frit and filler) showed CTE in the range of 70-83 x $10^{-7}/K$ and flowability of 14-20mm. It can be a candidate for the replacement of PbO system.

• Journal of the Korean Ceramic Society
• /
• v.48 no.1
• /
• pp.52-56
• /
• 2011

Silicon carbide (SiC) is a candidate material for heat exchangers for VHTR (Very High Temperature Gas Cooled Reactor) due to its refractory nature and high thermal conductivity. This research has focused on demonstration of physical properties and mock-up fabrication for the future heat exchange applications. It was found that the SiC-based components can be applied for process heat exchanger (PHE) and intermediate heat exchanger (IHX), which are operated at $400{\sim}1000^{\circ}C$, based on our examination for the following aspects: optimum fabrication technologies (design, machining and bonding) for compact design, thermal conductivity, corrosion resistance in sulfuric acid environment at high temperature, and simulation results on heat transferring and thermal stress distribution of heat exchanger mock-up.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.11a
• /
• pp.818-822
• /
• 2000

The low density, sustained high temperature strength and excellent resistivity to acid materials have made them strong candidate materials for future aerospace or medical applications. Nowadays their usage has already been broaden to everyday's commercial applications such as golf club heads, finger rings and many decorative items, Anticipating the general use of this material and development of the titanium alloys in domestic furnaces, the review and the study of the machining parameters for those alloys are deemed necessary. The present studies are concentrated to the machining parameters of the Ti-6Al-4V alloys due to their dominant position in the production of titanium alloys.

• Applied Microscopy
• /
• v.45 no.2
• /
• pp.52-57
• /
• 2015

Bulk metallic glass (BMG) shows higth strength, high elastic limit, corrosion resistance and good wear resistance and soft magnetic properties and has been considering as a candidate for new structural materials. But they show limited macroscopic plasticity and lack of tensile ductility due to highly localized shear deformation, which should be solved for real structural application. In this paper researches on the enhancement of plasticity of BMG were reviewed briefly. Introducing heterogeneous structure in glass is effective to induce more shear transformation zones (STZs) active for multiple shear band initiation and also to block the propagating shear band. Several methods such as BMG alloy design for high Poisson's ratio, addition of alloying element having positive heat of mixing, pre-straining BMG and variety of BMG composites have been developed for homogenous distribution of locally weak region, where local strain can be initiated. Therefore enhancement of plasticity of BMG is normally accompanied with some penalty of strength loss.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.20 no.5
• /
• pp.436-442
• /
• 2007

Physical properties and impedance-humidity characteristics of carbon nitride films were investigated for micro-humidity-sensors. Carbon nitride films were deposited in low temperature and low power for application of semiconductor fabrication process, and empirical equation was proposed for thickness evaluation. Deposited films had an uniform and compact surface comparing with previously reported results, which was expected a good candidate for humidity sensing materials. Carbon nitride humidity sensors based on Si substrate revealed good humidity-impedance characteristics with a wide range of relative humidity and showed low hysteresis.

• Applied Science and Convergence Technology
• /
• v.24 no.6
• /
• pp.245-249
• /
• 2015

Vertically coupled low density InGaAs quantum dots (QDs) buried in GaAs matrix were grown with migration enhanced molecular beam epitaxy method as a candidate for quantum information processing devices. We performed excitation power-dependent photoluminescence measurements at cryogenic temperature to analyze the effects of vertical coupling according to the variation in thickness of spacer layer. The more intense coupling effects were observed with the thinner spacer layer, which modified emission properties of QDs significantly. The low surface density of QDs was observed by atomic force microscopy, and scanning transmission electron microscopy verified the successful vertical coupling between low density QDs.

• Journal of Welding and Joining
• /
• v.31 no.3
• /
• pp.22-30
• /
• 2013

Due to ELV banning, automotive electronics cannot use four kinds of heavy metal element (Pb, Hg, Cd, $Cr^{6+}$) from 2016. Therefore, this study was focused on degradation characteristics of Sn-3.0Ag-0.5Cu Lead-free solder joint with OSP and ENIG finsh under various reliability assessment method, as like to thermal shock test and high temeprature/high humidity test with test duration for cabin electronics. Also, we compared bonding strength degradation to other advanced research results of electronic control unit for engine room because of difference service temperature with mount location in automotive. Whisker growth phenomenon and mitigation method which were essentially consideration items for Pb-free car electronics were examined. Conformal coating is a strong candidate for mitigating whisker growth in automotive electronics. Necessary condition to adapt Pb-free in car electronics was shown.