• Korean Journal of Materials Research
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• v.17 no.4
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• pp.222-226
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• 2007

[ $SiO_2$ ]thin films containing Si-nanocrystals and $Er^{3+}$ were fabricated by the RF-sputtering method. Intense emission of $Er^{3+}$ was observed at 1530 nm region after the annealing of the film at $1050^{circ}C$ for 5 min. Channel waveguides were fabricated using such films for the core. The films containing Si higher than 2.4 at% exhibited the change in stress from compression to tension after annealing, which induced the fatal loss-increase in waveguide. The optical gain might be attained by the Er-doped waveguide with Si lower than 2.4 at% by a visible-light-excitation.

• Korean Journal of Materials Research
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• v.17 no.3
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• pp.132-136
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• 2007

Oxidation resistance of sintered ${\beta}-FeSi_{2}$ was investigated at intermediate temperature range in air atmosphere. Fully dense and porous bodies of ${\beta}-FeSi_{2}$ samples were fabricated by using the Spark Plasma Sintering (SPS). They were annealed at $900^{\circ}C$ for 5days to obtain ${\beta}-FeSi_{2}$ phase. The bulk samples were oxidized at $800,\;900\;and\;950^{\circ}C$ in air atmosphere. The high temperature oxidation tests reveal that amorphous $SiO_{2}$ layer, similar to Si was formed and grew parabolically on ${\beta}-FeSi_{2}$. Accelerated oxidation is not observed as well as cracks and grain boundary oxidation. Granular ${\varepsilon}-FeSi$ was developed below the oxide layer as a result of oxidation of ${\beta}-FeSi_{2}$. Oxidation resistance of sintered ${\beta}-FeSi_{2}$ was excellent for high-temperature thermoelectric application.

• Corrosion Science and Technology
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• v.20 no.5
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• pp.249-255
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• 2021

In this work, we proposed a facile method to fabricate the three-dimensional porous copper current collector (3D Cu CC) for a Si-dominant anode in a Li-ion battery (LiB). The 3D Cu CC was prepared by combining chemical etching and thermal reduction from a planar copper foil. It had a porous layer employing micro-sized Cu balls with a large surface area. In particular, it had strengthened attachment of Si-dominant active material on the CC compared to a planar 2D copper foil. Moreover, the increased contact area between a Si-dominant active material and the 3D Cu could minimize contact loss of active materials from a CC. As a result of a battery test, Si-dominant active materials on 3D Cu showed higher cyclic performance and rate-capability than those on a conventional planar copper foil. Specifically, the Si electrode employing 3D Cu exhibited an areal capacity of 0.9 mAh cm^-2 at the 300^th cycles (@ 1.0 mA cm^-2), which was 5.6 times higher than that on the 2D copper foil (0.16 mAh cm^-2).

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.411-412
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• 2008

The chromatic dispersion of the germano-silicate optical fiber incorporated with Si nanocrystals was determined with the aid of simulation and demonstrated using experiments, which showed dependence of the launched power and the pump wavelength due to optical nonlinearity of the fiber.

• Laser Solutions
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• v.13 no.1
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• pp.6-10
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• 2010

Crystallization of 100 nm thick amorphous silicon (a-Si) films on glass substrates was carried out by using a double laser irradiation method. Depending on a-Si deposition method or glass types, the quality of crystallized silicon film varies significantly. For a-Si films deposited with high concentration of impurities, large grains or high crystallinity can not be achieved. Crystallization with different a-Si deposition methods confirmed that for the polycrystallization of a-Si films on glass substrates, controlling the impurity density during substrate preparation is critical.

• Proceedings of the Korean Vacuum Society Conference
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• 2005.08a
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• pp.58-58
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• 2005

• Journal of Environmental Science International
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• v.28 no.11
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• pp.959-969
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• 2019

This study sought to contribute to the revitalization of local economy by developing a natural recreation forest, which is the base of ecotourism recreation, through utilizing forest resources and the natural environment of Gwangju-si. The study conducted a feasibility assessment through on-site surveys such as the suitability of the candidate sites, location analysis, and possibility of damage to the forest, before developing recreation forest sites in Gwangju-si and, based on the result, selected appropriate subject sites. The candidates for this study were 5 forest sites such as one site in the Mokheon-dong area, two in the Docheok-myeon area, and one in the Toechon-myeon area. For this study, the current status of the natural recreation forest was surveyed, its feasibility index and assessment process were investigated, and the local status and related regulations of Gyeonggi-do and Gwangju-si were reviewed. The final subject sites were selected after feasibility assessment utilizing assessment index in order to evaluate the candidate sites. The feasibility assessment was conducted after three separate on-site surveys for each candidate site between October 2018 and January 2019 utilizing "The Feasibility Assessment Criteria for Natural Recreation Forest (Notification 2018-71)" of the Korean Forest Service. The items instrumental to the feasibility assessment were classified into landscape, location, water system, induction of recreation, and development condition; the assessment was made after redefining each item into detailed items. Through this process, the Usan-ri area was selected as the final site for developing natural recreation forest, having obtained more than 100 points according to "The Feasibility Assessment Criteria for Natural Recreation Forest" of the Korean Forest Service. In order to develop natural recreation forest in the Usan-ri area in the future, further discussion is necessary with the relevant departments in consideration of the degree of ecological zoning map.

• Proceedings of the Korean Vacuum Society Conference
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• 2006.02a
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• pp.148-148
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• 2006

• Proceedings of the Korean Vacuum Society Conference
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• 2006.08a
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• pp.135-135
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• 2006

• Proceedings of the Membrane Society of Korea Conference
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• 2005.05a
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• pp.126-127
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• 2005