• 한국재료학회지
• /
• 제30권3호
• /
• pp.111-116
• /
• 2020

Two different casting speeds of 60 and 80mm/min are adopted to determine the effect of casting speed on the microstructure and mechanical properties of Al-Mg-Si/Al hybrid material prepared by duo-casting. The obtained hybrid material has a uniform and straight macro-interface between the pure Al side and the Al-Mg-Si alloy side at both casting speeds. When the casting speed is increased to 80mm/min, the size of primary α phases in Al-Mg-Si alloy decreases, without change of shape. Although the Al-Mg-Si alloy produced at higher casting speed of 80mm/min shows much higher ultimate tensile strength (UTS) and 0.2 % proof stress and lower elongation, along with higher bending strength compared to the case of the 60mm/min in casting speed, the tensile properties and bending strength of the hybrid material, which are similar to those of pure Al, are the same regardless of the increase of casting speed. Despite the different casting speeds, deformation and fracturing in hybrid materials are observed only on the pure Al side. This indicates that the macro-interface is well-bonded, allowing it to endure tensile and bending deformation in all hybrid materials.

• 한국세라믹학회지
• /
• 제54권5호
• /
• pp.366-379
• /
• 2017

Nanostructured materials have attracted considerable research interest over the recent decades because of their potential applications in nanoengineering and nanotechnology. On the other hand, the developments in nanotechnology are strongly dependent on the availability of new materials with novel and engineered morphologies. Among the novel nanomaterials reported thus far, composite nanofibers (NFs) have attracted considerable attention in recent years. In particular, metal oxide NFs have great potential for the development of gas sensors. Highly sensitive and selective gas sensors can be developed by using composite NFs owing to their large surface area and abundance of grain boundaries. In composite NFs, gas sensing properties can be enhanced greatly by tailoring the conduction channel and surface properties by compositional modifications using the synergistic effects of different materials and forming heterointerfaces. This review focuses on the gas sensing properties of composite NFs synthesized by an electrospinning (ES) method. The synthesis of the composite NFs by the ES method and the sensing mechanisms involved in different types of composite NFs are presented along with the future perspectives of composite NFs.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
• /
• pp.546-549
• /
• 2009

In this paper, we investigated the effects of different source/drain (S/D) electrode materials in thin film transistors (TFTs) based on indium-gallium-zinc oxide (IGZO) semiconductor. A transfer length and effective resistances between S/D electrodes and amorphous IGZO thin-film transistors were examined. Intrinsic TFT parameters were extracted by the transmission line method (TLM) using a series of TFTs with different channel lengths measured at a low drain voltage. The TFTs fabricated with Cu S/D electrodes showed the lowest contact resistance and transfer length indicating good ohmic characteristics, and good transfer characteristics with a field-effect mobility (${\mu}_{FE}$) of 10.0 $cm^2$/Vs.

• Journal of Information Science Theory and Practice
• /
• 제9권4호
• /
• pp.1-14
• /
• 2021

Library communities face many problems and limitations in describing alternative format materials based on the traditional MAchine Readable Cataloging (MARC) structure. To address these problems, this research proposes an XML-based descriptive metadata framework that establishes general but fundamental bibliographic aspects of various alternative format materials by providing core elements that are essential in describing these materials. Different from existing bibliographic structures, the proposed metadata framework can represent a fundamental descriptive structure by establishing four upper-level categories, 17 core elements, and 10 sub-elements in a hierarchical structure optimized to alternative format materials. By using this principal descriptive structure, the proposed metadata framework can guide different institutions in the creation of bibliographic records for these materials in a consistent way. It is also expected to address the difficulties in describing alternative format materials in library communities and enhance the information accessibility of individuals with various types of disabilities. In addition, the proposed metadata framework is an alternative approach which functions as a mediator between heterogeneous characteristics of alternative format materials and the existing bibliographic structures in library communities.

• International journal of advanced smart convergence
• /
• 제7권4호
• /
• pp.84-91
• /
• 2018

In this paper, we simulated three different HV systems and analyzed of each vacuum characteristics by VacCAD modelling. In each of modelled vacuum systems, selection of chamber materials, combination of rough pump with high vacuum pump and conductance of roughing line (diameter and length) were proposed as system variables. In the modelling of chamber materials, the pumping times to ultimate pressures of different chamber materials (stainless steel, aluminum) were compared by the variations of chamber volume. In this model, the effects of outgassing dependent on the chamber materials was also simulated and aluminum was estimated to optimum chamber materials. It was also obtained that modelling of vane and roots pump with diffusion pump and diameter, length of $50{\times}250$ [mm]roughing line were characterized as optimum variables to reach the ultimate pressure of 10E-7 [mbar] most effectively. Optimum design factors for vacuum characteristics of modelled vacuum system were achieved by VacCAD simulations. Feasibility of VacCAD as vacuum simulator was verified and applications of VacCAD expected to be increased to fields in vacuum needed.

• 한국재료학회지
• /
• 제29권11호
• /
• pp.664-669
• /
• 2019

In this paper, a water-based green polymer mud is synthesized by simple compounding method. Effects of different kinds of tackifiers, their molecular weight on the viscosity of polymer mud and the effects of different fluid loss additives on mud fluid loss are studied. The results show that when polystyrene and anionic polyacrylamide with molecular weight of 8 ~ 10 million are used as the main thickening ingredient, polymer mud with high viscosity and high stability can be obtained. When the prepared polymer mud is formulated as NPAM: PEO: Hydroxypropyl cellulose(HPC) : Water = 42:10:10:100000 (unit: kg), the viscosity can reach 20.6 s, the filtration loss in 7.5 min is 24 mL, and the sand content is only 0.1 %. Compared with traditional bentonite mud, the green environment-friendly polymer mud has the advantages of small amount of waste, low environmental pollution, and low pulping cost, and can meet the construction needs for most topography and geomorphology drilling engineering.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2007년도 추계학술발표대회 및
• /
• pp.31.1-31.1
• /
• 2007

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 2008년도 Asian Magnetics Conference
• /
• pp.236.1-236.1
• /
• 2008

• Journal of Mechanical Science and Technology
• /
• 제20권4호
• /
• pp.513-521
• /
• 2006

The performances of porous bearings under different operating conditions were experimentally investigated in this study. Material groups studied are 90%Cu + 10%Sn bronze and 1%C + % balance Fe iron-based self-lubricating P/M bearings at constant (85%) density. In the experiments, the variation of the coefficient of friction and wear ratio of those two different group materials for different sliding speeds, loads, and temperatures were investigated. As a result, the variation of the friction coefficient-temperature for both constant load, and constant sliding speed, friction coefficient-average bearing pressure, PV-wear loss and temperature-wear loss curves were plotted and compared with each other for two materials, separately. The test results showed that Cu-based bearings have better friction and wear properties than Fe-based bearings.

• 한국실내디자인학회논문집
• /
• 제38호
• /
• pp.125-133
• /
• 2003

The apartment house is one of the representative housing types in Korea. However, it has not met the diverse and individualized needs of their residents. This study was intended to identify the residents' preference of interior design in apartment houses and suggest the guidelines for the diversity of Intoner design In apartments. The subjects were 412 apartment residents who lived in Haeundae, Busan. They were asked about their preference for interior images of each room and finishing materials. The findings were as follows. 1) The apartment interior images were composed of nine main factors. 2) The residents preferred to 'practical' interior image in apartment and different interior images for each room. 3) The residents preferred interior images were different by their housing sizes and space organization types. 4) The residents preferred to different finishing materials for each room..