• Structural Engineering and Mechanics
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• v.24 no.5
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• pp.561-584
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• 2006

The paper presents results of parametric studies, and an overall approach for the design of a modular bridge system which incorporates a steel-reinforcement free concrete slab cast on top of carbon FRP stiffened deck panels which act as both structural formwork and flexural reinforcement, spanning between hollow box type FRP girders. Results of the parametric studies are highlighted to elucidate important relationships between critical configurational parameters and empirical equations based on numerical studies are presented. Results are discussed at the level of the individual deck and girder components, and as a slab-on-girder bridge system. An overall design methodology for the components and bridge system including critical performance checks is also presented.

• Steel and Composite Structures
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• v.26 no.5
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• pp.649-662
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• 2018

In this study, based on the three-dimensional theory of elasticity, free vibration characteristics of sandwich sectorial plates with multiwalled carbon nanotube-(MWCNT)-reinforced composite core are considered. Modified Halpin-Tsai equation is used to evaluate the Young's modulus of the MWCNT/epoxy composite samples by the incorporation of an orientation as well as an exponential shape factor in the equation. The exponential shape factor modifies the Halpin-Tsai equation from expressing a straight line to a nonlinear one in the MWCNTs wt% range considered. In this paper, free vibration of thick functionally graded sandwich annular sectorial plates with simply supported radial edges and different circular edge conditions including simply supported-clamped, clamped-clamped, and free-clamped is investigated. A semi-analytical approach composed of two-dimensional differential quadrature method and series solution are adopted to solve the equations of motion. The material properties change continuously through the core thickness of the plate, which can vary according to a power-law, exponentially, or any other formulations in this direction. This study serves as a benchmark for assessing the validity of numerical methods or two-dimensional theories used to analysis of laminated sectorial plates.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.467.2-467.2
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• 2014

유기태양전지는 친환경 에너지 소스로써 저가 대량 생산이 가능하고 특히 유연한 기판에 적용이 가능하여 많은 관심을 받고 있다. 그럼에도 불구하고 기존에 사용되는 indium tin oxide (ITO)의 사용으로 인한 유연성 부족으로 대체되는 투명전극의 개발이 요구되어지고 있다. 이로 인해 carbon nanotubes, graphene, thin metals, metal grids, and conducting polymers 등이 연구되고 있으며, 이중 Silver nanowires (Ag NWs)를 이용한 방식도 많은 관심과 함께 전기광학적 특성에 대한 연구가 진행되고 있다. 하지만 유기전자소자에 사용되기에는 몇 가지 문제점이 발생하는데 이를 해결하기 위한 노력이 다양하게 이루어지고 있다. 특히 다양한 물질의 혼합을 통해 개선하고자 하는 노력이 증가하고 있는데 적층구조의 전도성필름 형성을 통해 ITO-free OPVs에서 Ag nanowire를 transparent conductive electrodes로 활용하였다. Ag NWs층과 PEDOT:PSS layer의 복합화를 통해 저가의 ITO-free OPVs용 transparent anodes가 가능해졌다.

• Journal of Sensor Science and Technology
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• v.16 no.6
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• pp.449-456
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• 2007

The work described in this study concerns the development of a disposable amperometric sensor for the electrochemical detection of a well-known aqueous pollutant, free available chlorine (FAC). The FAC sensor developed used screen printed carbon electrodes (SPCEs) coupled with immobilised syringaldazine, commonly used as an indicator in photometric FAC detection, which was directly immobilised on the surface of SPCEs using a photopolymer PVA-SbQ. To enable in-field analysis of FAC, a prototype hand-held electrochemical analyzer has been developed to withstand the environment with its rugged design and environmentally sealed connections; it operates from two PP3 (9 volt) batteries and is comparable in accuracy and sensitivity to commercial bench top systems. The sensitivity of the FAC sensor developed was $3.5{\;}nA{\mu}M^{-1}cm^{-2}$ and the detection limit for FAC was found to be $2.0{\;}{\mu}M$.

• Advances in materials Research
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• v.9 no.4
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• pp.323-335
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• 2020

This article reviews findings and progresses in the past decade on manganese-aluminium (MnAl) based magnets as the interest has been revived to fulfill their potential as commercial magnets. The challenges in developments of these rare-earth-free magnets are to acquire a high remanence and coercivity from the ferromagnetic τ-phase in MnAl alloys. To this end, the phase transformation to this τ-MnAl with L10 body centered tetragonal structure has been promoted by a variety of methods and a few percents of carbon (C) is often added to prevent the phase decomposition. Magnetization and coercivity are not only influenced by the phase composition but also the microstructure. The fabrication processes and factors affecting the phase and microstructure are therefore covered. Finally, the productions of bulk MnAl magnets are addressed.

• Smart Structures and Systems
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• v.22 no.1
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• pp.105-120
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• 2018

In this paper, the nonlinear free and forced vibration responses of sandwich nano-beams with three various functionally graded (FG) patterns of reinforced carbon nanotubes (CNTs) face-sheets are investigated. The sandwich nano-beam is resting on nonlinear Visco-elastic foundation and is subjected to thermal and electrical loads. The nonlinear governing equations of motion are derived for an Euler-Bernoulli beam based on Hamilton principle and von Karman nonlinear relation. To analyze nonlinear vibration, Galerkin's decomposition technique is employed to convert the governing partial differential equation (PDE) to a nonlinear ordinary differential equation (ODE). Furthermore, the Multiple Times Scale (MTS) method is employed to find approximate solution for the nonlinear time, frequency and forced responses of the sandwich nano-beam. Comparison between results of this paper and previous published paper shows that our numerical results are in good agreement with literature. In addition, the nonlinear frequency, force response and nonlinear damping time response is carefully studied. The influences of important parameters such as nonlocal parameter, volume fraction of the CNTs, different patterns of CNTs, length scale parameter, Visco-Pasternak foundation parameter, applied voltage, longitudinal magnetic field and temperature change are investigated on the various responses. One can conclude that frequency of FG-AV pattern is greater than other used patterns.

• Steel and Composite Structures
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• v.28 no.5
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• pp.541-557
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• 2018

This paper presents the influence of carbon nanotubes (CNTs) waviness and aspect ratio on the vibrational behavior of functionally graded nanocomposite sandwich annular sector plates resting on two-parameter elastic foundations. The carbon nanotube-reinforced (CNTR) sandwich plate has smooth variation of CNT fraction along the thickness direction. The distributions of CNTs are considered functionally graded (FG) or uniform along the thickness and their mechanical properties are estimated by an extended rule of mixture. In this study, the classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube random contact, which explicitly accounts for the progressive reduction of the tubes' effective aspect ratio as the filler content increases. Effects of CNT distribution, volume fraction, aspect ratio and waviness, and also effects of Pasternak's elastic foundation coefficients, sandwich plate thickness, face sheets thickness and plate aspect ratio are investigated on the free vibration of the sandwich plates with wavy CNT-reinforced face sheets. The study is carried out based on three-dimensional theory of elasticity and in contrary to two-dimensional theories, such as classical, the first- and the higher-order shear deformation plate theories, this approach does not neglect transverse normal deformations. The sandwich annular sector plate is assumed to be simply supported in the radial edges while any arbitrary boundary conditions are applied to the other two circular edges including simply supported, clamped and free.

• The Korean Journal of Zoology
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• v.7 no.2
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• pp.1-5
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• 1964

Carbonyl compounds, glycine, ammonia, carbon dioxide and hydrogen have been identified in gamma-irradiated oxygenated aqueous solutions of triglycine. The reactions occurring in this system are postulated only by representing the initial process and the final products. The triglycine molecule undergoes a reaction to form an intermediate giving rise to carbonyl compounds and acid amides. These compounds are decomposed to acetamide, glycine, glyoxylic acid, formic acid, oxalic acid, ammonia, and carbon dioxide by free radical attack in the primary and/or secondary reactions. It is also possible that the unrecognized reactions may give rise to products formed by radical-radical combinations. Satisfactory material balance for all the products have to wait until the completion of a study now in progress.ogress.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.150-155
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• 2006

Carbon nanotubes backlight unit (CNT-BLU) that lightened by field emission was developed into practicability. According to our novel structure, AC mode circuit design and simple printing process, CNT-BLU could achieve 85% of uniformity, 8000 nits of brightness and low material and fabrication cost. Based on these performances, this new planar backlight technology has chances to proceed to mass production and has the potential to replace traditional backlight technology because of its good properties, like the simple processes, easy to large scale, low surface temperature, low power consumption, optical film-free and Hg-free, etc.

• Journal of the Korean Ceramic Society
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• v.48 no.1
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• pp.1-5
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• 2011

Silicon carbide (SiC) has recently drawn an enormous industrial interest because of its useful mechanical properties such as thermal resistance, abrasion resistance and thermal conductivity at high temperature. RF Thermal plasma (PL-35 Induction Plasma, Tekna CO., Canada) has been utilized for synthesis of high purity SiC powder from cheap inorganic solution (Tetraethyl Orthosilicate, TEOS). It is found that the powders by thermal plasma consist of SiC with free carbon and amorphous silica ($SiO_2$) and, by thermal treatment and HF treatment, the impurities are driven off resulting high purity SiC nano-powder. The synthesized SiC powder lies below 30 nm and its properties such microstructure, phase composition, specific surface area and free carbon content have been characterized by X-ay diffraction (XRD), field emission scanning electron microscopy (FE-SEM), thermogravimetric (TG) and Brunauer-Emmett-Teller (BET).