• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.31-34
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• 2006

The characteristic of carbon nano fiber (CNF) as electron emitters was described. Carbon nano fiber (CNF) of herringbone was prepared by thermal chemical vapor deposition(CVD), mixed with binders and conductive materials, and then were formed by screen-printing process. In order to increase effectively field emissions, the surface treatment of rubbing & peel-off was applied to the printed CNF emitters on cathode electrode. The measurements of field emission properties were carried out by using a diode structure inline vacuum chamber. CNF of herringbone type showed good emission properties that a turn on field was as low as $2.5V/{\mu}m$ and current density was as large as $0.15mA/cm^2$ of $4.5V/{\mu}m$ with electric field. After the vacuum packaged panel of 5-inch in diagonal, the measured white brightness was as high as $7000cd/m^2$ at 1900V of anode and 700V of gate voltage.

• Korean Journal of Metals and Materials
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• v.47 no.1
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• pp.1-6
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• 2009

Magnesium alloys are drawing a lot of attention and have been extensively studied. The major obstacle to the practical application of the alloys is the poor formability at room temperature, originating basically from the insufficient number of slip system. Development of a proper texture is one promising solution to improve the formability. In the present work, after extrusion and full annealing, microstructures, texture developments and tensile properties of AZ31 Mg alloys are studied. After full annealing strong <1010>||ED fiber texture and weak <1120>+<1230>||ED fiber texture (c-axes in the radial direction) were developed. The textures are distinctly influencing the tensile properties, which can be understood in terms of the activation of basal slip modes. With the random orientation, which is developed in the $45^{\circ}$ sample to the extrusion direction, the better workability can be achieved at room temperature.

• Korean Journal of Materials Research
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• v.17 no.7
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• pp.390-395
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• 2007

We systematically investigated the effects of InAs coverage variation, two-step annealing and an asymmetric InGaAs quantum well (QW) on the structural and optical characteristics of InAs quantum dots (QDs) by using atomic force microscopy (AFM), transmission electron microscopy (TEM) and photoluminescence (PL) measurement. The transition of size distribution of InAs QDs from bimodal to multi-modal was noticeably observed with increasing InAs coverage. By means of two-step annealing, it is found that significant narrowing of the luminescence linewidth (from 132 to 31 meV) from the InAs QDs occurs together with about 150 meV blueshift, compared to as-grown InAs QDs. Finally, the InAs QDs emitting at longer wavelength of $1.3\;{\mu}m$ with narrow linewidth were grown by an asymmetric InGaAs QW. The excited-state transition for the InAs QDs with an asymmetric InGaAs QW was not noticeably observed due to the large energy-level spacing between the ground states and the first excited states. The InAs QDs with an asymmetric InGaAs QW will be promising for the device applications such as $1.3\;{\mu}m$ optical-fiber communication.

• Proceedings of the Korean Fiber Society Conference
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• 2002.04a
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• pp.309-312
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• 2002

The polymer nanocomposites are attracting considerable attention on account of the characteristic properties of nanoparticles have extremely large surface area per a unit mass. Recentry, mica-type silicates like montmorillonite have received a good deal of attention as effective nano-reinforcemen(1), but actually some critical problems such as the difficulties of exfoliation and surface modification, the weak heat-resistance of modifier, and inferior processability due to the increase in melt viscosity have restricted the mass production and various applications of the nanocoposite. (omitted)

• Proceedings of the Korean Fiber Society Conference
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• 2007.11a
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• pp.31-34
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• 2007

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• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.7
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• pp.1095-1099
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• 2002

We experimentally investigate the evolution of nanosecond Stokes pulses in a single-pass Raman laser pumped by a Q-switched Nd:YAG laser at 1064 na As a Raman medium, a GeO2-doped graded-index multimode fiber ot 220 m long Is used. We demonstrate that efficient generation of several Stokes components with 1.5∼2.7 nanosecond pulsewidth is obtained by varying the input pump energy.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.3
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• pp.339-345
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• 2012

Electrospun meshed poly-caprolactone PCL was patterned by femtosecond laser with linear grooves. As parametric variables, focus spot size, pulse energy, and scanning speed were varied to determine the affects on groove size and the characteristics of the electrospun fiber at the edges of these grooves. The femtosecond laser was seen to be an effective means for flexibly structuring the surface of ES PCL scaffolds and the width of the ablated grooves was well controlled by laser energy and focus spot size. The ablation threshold was measured to be $14.9J/cm^2$ which is a little higher than other polymers. These affects were attributed to optical multiple reflections inside nano-fibers. By the laser-induced plasma at higher pulse energies, some melting of fibers was observed.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.21-24
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• 2006

Based on the improvement in reinforcing SiC fibers and the utilization of very fine nano-SiC powders, the well known liquid phase sintering (LPS) process was drastically improved to become a new process called the Nano Infiltration and Transient Eutectic Phase (NITE) Process. Laboratory scale NITE-SiC/SiC composites demonstrated excellent mechanical properties, thermal conductivity, hermeticity and microstructure stability which made them attractive for not only energy application but many other industrial applications. For the real deployments of these materials, mass production system and evaluation methods, together with the design code and safety assurance systems are essential. The current efforts to establish these bases were introduced.

• Fibers and Polymers
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• v.7 no.2
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• pp.139-145
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• 2006

Cotton fabric was treated with montmorillonite (MMT) so as to evaluate its effectiveness on improving its wrinkle resistance. The MMT in emulsion form was applied to cotton fabric by padding and finally the wrinkle resistance of the MMT-treated cotton fabric was improved. Furthermore, instrumental methods were used for studying the presence of MMT particles on the cotton fabric surface. It was noted that nano-scale MMT particles adhered on the fiber surface and the particle size played an important role in influencing the wrinkle resistance of the cotton fabric. The experimental results are discussed thoroughly in this paper.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.597-600
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• 2014

In this work, the electromagnetic interference shielding effectiveness (EMI-SE) of carbon nanotube/carbon fiber-reinforced HDPE matrix composites are investigated with various preparation conditions, such as the carbon fiber and carbon nanotube content, the presence of metal additives, as well as mixing speed and time. It was found that the EMI-SE of the composites increased with filler contents and metal additives. These results indicate that the content and length of carbonaceous fillers determine the electric networks in the composites, resulting in the control of the EMI-SE of the composites.