• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.3
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• pp.119-123
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• 2011

Carbon nanotilaments (CNFs) could be synthesized on nickel catalyst layer-deposited silicon oxide substrate using $C_2H_2$ and$H_2$ as source gases under thermal chemical vapor deposition system. By the incorporation of $SF_6$ as a cyclic modulation manner, the geometries of carbon coils-related materials, such as nano-sized coil and wave-like nano-sized coil could be observed on the substrate. The characteristics (formation density and morphology) of as-grown CNFs with or without $SF_6$ incorporation were investigated. Diameter size reduction for the individual CNFs-related shape and the enhancement of the formation density of CNFs-related material could be achieved by the incorporation of $SF_6$ as a cyclic modulation manner. The cause for these results was discussed in association with the slightly increased etching ability by $SF_6$ addition and the sulfur role in SF 6 for the geometry change.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.331-337
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• 2000

When microorganism is injected into porous medium such as soils, biomass retained in the pore. Bacteria within these microcolonies produced large amounts of exopolysaccharides and formed a plugging biofilm. Soil pore size and shape are varied from the initial condition as a result of biofilm formation, which make hydraulic conductivity reduced and friction rate between soil aggregates increased. In this research, hydraulic conductivity reduction was measured after microorganism are inoculated and cultured with synthetic substrate and nutrient. Also, pore sand of before and after biofilm formation compared with scanning electron microscopy. Hydraulic conductivity of Sand and Poorly Graded Sand was decreased approximately 1/10∼1/100 after biomass inoculation and cultivation. Biofilm attached on soil aggregates is resistant to acidic or basic condition.

• Tribology and Lubricants
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• v.26 no.5
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• pp.297-302
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• 2010

This study is focused on the resin layer formation of UV imprinting process by changing imprinting pressure and period. The mold shape is made for the process of window open over the pattern transfer area and the imprinting period is assigned as the time just before the UV light curing. The residual layer is measured by changing the imprinting period and pressure magnitude, and the measured data of residual layer provides useful information for the design of the process conditions of imprinting processes.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.96-98
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• 2003

The evolution of texture and microstructure during continuous confined strip shearing (CCSS) in aluminum 3003 alloy sheets was investigated. The tools of CCSS based on the equal channel angular pressing (ECAP) were designed to provide a constant shear deformation of the order of 0.5 per pass while preserving the original sheet shape. FEM results indicated that the shear formation is not homogeneous throughout the sample thickness, in particular at the surface layers. A randomization of textures took place during the CCSS deformation. Observations by TEM and EBSD revealed the formation of sub-micrometer sized grains after CCSS.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1315-1318
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• 2004

Nano-scale fabrication of silicon substrate in an aqueous solution based on the use of atomic force microscopy was demonstrated. A specially designed cantilever with diamond tip, allowing the formation of damaged layer on silicon substrate easily by a simple scratching process (Tribo-Nanolithography, TNL), has been applied instead of conventional silicon cantilever for scanning. A slant nanostructure can be fabricated by a process in which a thin damaged layer rapidly forms in the substrate at the diamond tip-sample junction along scanning path of the tip and simultaneously the area uncovered with the damaged layer is being etched. This study demonstrates how the TNL parameters can affect the formation of damaged layer and the shape of 3-D structure, hence introducing a new process of proximal nanolithography in aqueous solution.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.4
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• pp.135-141
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• 2001

An experimental study to find the effect of processing parameters for self-healing microcapules is performed. These microcapsules can be applied to accomplish the healing of delamination damage in woven E-glass/epoxy composites. This paper introduces the self-healing concept and presents a method for solving the microcapsule size and shape. Additionally, processing parameters are varied during the formation of microcapsules and these capsules are observed through optical microscope. To obtain thermogravimetric(TG) curve for the manufactured microcapsules, TGA tests are executed. From these results, the best processing conditions for the formation of capsules are found as follows: (1) temperature of solution $ 50^{\circ}C$, (2) potential of hytdrogen(pH) 3.5ppm, and (3) agitation 500~600rpm.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.153-159
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• 2007

The performance of a direct-injection type diesel engine often depends on the strength of air flow in the cylinder, shape of combustion chamber, the number of nozzle holes, etc. This is of course because the process of combustion in the cylinder was affected by the mixture formation process. In the present paper, high speed photography was employed to investigate the effectiveness of holes penetrated from the bottom of cavity wall to piston crown for some more useful utilization of air. The holes would function to improve mixing of fuel and air by the increase of air flow in the cylinder. The results obtained are summarized as follows, (1) Activated first of the combustion by shorten of ignition timing and rapid flame propagation (2) Raised the combustion peak pressure, more close to TDC the formation timing of peak pressure.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2002.05a
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• pp.35-35
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• 2002

Atomic force microscopy was applied to study the formation and growth mechanism of thin chrome layers prepared under various pulse plating conditions. The chrome was electro-deposited from an electrolyte bath containing 250 gl-l of chromic acid, 25 gl-l of sulfuric acid using direct current density of $1.6{\;}mA.$\textrm{mm}^{-2} and pulse currents with on-off time from 5 to 900 ms. The higher current density enhanced nucleation rate which resulted in refining grain size. The chrome growth kinetics determining nodule size and shape significantly depends on the duration of on-time rather than duration of off-time and on/off time ratio.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.366-369
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• 1992

In this paper we propose a 3-dimensional formation system using an arc welding robot. The principle of our system is just only to accumulate welding beads, so that the target 3-dimensional surfaces can be built up. Considering the effects of the gravity on the arc welding, the welding torch is steadily clamped and the position and the posture of the target board on which target work is formed is controlled by a 6-axis robot hand. Movements of the target board are controlled considering the 3dimensional shape of the target and the accumulating speed of the welding bead. In order to realize such systems, a distance sensor is mounted on the tip of the robot hand. And a coordinate transformation technique is employed

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.129-132
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• 1996

Surface modification like cone formation on Pulsed laser deposition (PLD) occurs in YBCO target surface irradiated by laser beam. Cone formation results in a reduction of deposition rate, so that it is significant obstacles to an efficient deposition process. With the change of various conditions such as the number of laser shot, target density, direction of incoming laser beam, we have systematically analyzed the modification of target surface. Because cones formed by beam-target interactions grow in direction of incoming laser beam, we have used the method of rotating the target position by 180$^{\circ}$ with the same number and position of laser shot. Experimental results of losing the directionality and changing the shape of cones formed on laser irradiated YBCO target surface is obtained by the SEM image. Also, we have observed that the size of cones formed on target by pulsed laser became larger with increasing the number of laser shots.