• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2909-2912
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• 2010

Hydrogenated microcrystalline silicon (${\mu}c$-Si:H) thin film for solar cells is prepared by plasma-enhanced chemical vapor deposition and physical properties of the ${\mu}c$-Si:H p-layer has been investigated. With respect to stable efficiency, this film is expected to surpass the performance of conventional amorphous silicon based solar cells and very soon be a close competitor to other thin film photovoltaic materials. Silicon in various structural forms has a direct effect on the efficiency of solar cell devices with different electron mobility and photon conversion. A Raman microscope is adopted to study the degree of crystallinity of Si film by analyzing the integrated intensity peaks at 480, 510 and $520\;cm^{-1}$, which corresponds to the amorphous phase (a-Si:H), microcrystalline (${\mu}c$-Si:H) and large crystals (c-Si), respectively. The crystal volume fraction is calculated from the ratio of the crystalline and the amorphous phase. The results are compared with high-resolution transmission electron microscopy (HR-TEM) for the determination of crystallinity factor. Optical properties such as refractive index, extinction coefficient, and band gap are studied with reflectance spectra.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.32.1-32.1
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• 2018

Novel soft magnetic materials can be achieved by altering material properties such as morphology, composition, crystallinity, and grain size of soft magnetic alloys. Especially, magnetic properties (i.e., saturation magnetization, coarcivity) of soft magnetics are significantly affected by grain boundaries which act as a control of magnetic domain wall movement. Thus, we herein develop a two-step electroless plating method to control morphology and grain size of FeCo films for excellent magnetic properties. Accordingly, the chemical composition to control the degree of polarization of FeCo alloys was altered by electroless deposition parameters; for example, electrolyte concentration and temperature. The grain size and crystallinity of FeCo alloys was dramatically affected by the reaction temperature because the grain growth mechanism dominantly occurs at $90^{\circ}C$ where as the neucleation only happens at $50^{\circ}C$. By simply controlling the temperature, the micron-sized FeCo grains embedded FeCo film was synthesized where the large grains allow high magnetization originated from larger magnetic domain with low corecivity and the nano-sized grains allow excellent soft magnetic properties due to the magnetic correlation length.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2008.04a
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• pp.222-228
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• 2008

The chemical composition and thermal, crystal characterization of oak mushroom waste were investigated in comparison with those normal oak wood for utilization of cellulose from oak mushroom waste. The oak mushroom waste contained a higher percentage of ash, and hot water extractives than oak wood. This results indicated that the materials inside the body are easily decomposed during the oak mushroom cultivation. The lower percentage of holocellulose and a-cellulose of oak mushroom waste caused by fungal decomposition too. Whereas, the thermal decomposition behavior and crystallinity of oak mushroom waste was similar to that of normal oak wood, which indicated that the cellulose characterization of oak mushroom waste is resistant to fungal decomposition. In additionally, a degree of polymerization of oak mushroom waste must be investigate for examination of cellulose crystalline characterization, especially.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.442-446
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• 2004

Reducing the particle size of drug materials down to submicron is an important matter in pharmaceutical industry. Cryogenic milling technology is one of the mechanical milling processes, which is mostly utilized in refining grain size of metal and ceramics at extremely low temperature environment. This technique has not been readily studied in application to medical and biotechnology. This paper, therefore, describes the application of cryogenic milling process to reduce particle size of Ibuprofen. The shape and size of the Ibuprofen particle before and after the cryogenic ball milling process were analyzed. XRD analysis was performed to examine a change in crystallinity of Ibuprofen by the cryogenic ball milling process. The results showed that the size of Ibuprofen particles was reduced to 1/10 or less of its initial size. The results also showed that the degree of crystallinity of Ibuprofen was slightly reduced after cryogenic ball milling with nitrogen

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.5
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• pp.320-323
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• 2018

SiGe thin films were deposited by remote plasma enhanced chemical vapor deposition (RPE-CVD) at $400^{\circ}C$ using $SiH_4$ or $SiCl_4$ and $GeCl_4$ as the source of Si and Ge, respectively. The growth rate and the degree of crystallinity of the fabricated films were characterized by scanning electron microscopy and Raman analysis, respectively. The optical and electrical properties of SiGe films fabricated using $SiCl_4$ and $SiH_4$ source were comparatively studied. SiGe films deposited using $SiCl_4$ source showed a lower growth rate and higher crystallinity than those deposited using $SiH_4$ source. Ultraviolet and visible spectroscopy measurement showed that the optical band gap of SiGe is in the range of 0.88~1.22 eV.

• Fibers and Polymers
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• v.7 no.4
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• pp.367-371
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• 2006

Thermal properties of copolyetherester/silica nanocomposites were examined by using DSC and TGA. The segmented block copolyetheresters with various hard segment structures and hard segment contents (HSC) were synthesized and their silica nanocomposite films were prepared by solution casting method. The nano-sized fumed silica particles were found to act as a nucleating agent of the copolyetheresters. The nanocomposites always showed reduced degree of supercooling or faster crystallization than the corresponding copolyetheresters. The nanocomposites also showed increased hard segment crystallinity except HSC 35 sample which had short hard segment length. In case of 2GT [poly(ethylene terephthalate)] copolyetheresters, which were not developed commercially because of their low crystallization rate, the hard segment crystallinity increased considerably. The copolyetherester/silica nanocomposites showed better thermal stability than copolyetheresters.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.11
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• pp.195-199
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• 2004

For the present study, the cryogenic ball milling process was applied to make Ibuprofen microsized. The cryogenic ball milling was performed at low temperature of about -18$0^{\circ}C$ for 6 hours. The particle size distribution was determined before and after the cryogenic process. X-ray diffraction (XRD) measurement was made to determine the effect of cryogenic process on the crystallinity of Ibuprofen. The results showed that the size of Ibuproffn was reduced about 10 times by the cryogenic process. The degree of crystallinity of Ibuproffn was slightly reduced by the cryogenic process.

• Journal of the Korean Ceramic Society
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• v.27 no.4
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• pp.521-528
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• 1990

Li2O.2SiO2 glass-ceramics were made from the melt by the nucleation and growth treatment. The optimum nucleation temperature and time were determined from DTA curves of as-quenched and thermally treated glasses, and found to be 44$0^{\circ}C$ and 3hrs. The optical microscopic technique was also used to support this result. The volume fractions of crystals present in the partially crystallized specimens were measured using the optical microscopy and the amorphous X-ray scattering methods. The degree of crystallization increased with increasing the crystallization temperature and time. The crystalline phase identified by X-ray diffraction was lithium disilicate. As the crystallinity increased up to 95%, the transmittance of glass-ceramics was decreased linearly. It was also found that for the same heat treatment condition (575$^{\circ}C$, 30min), a thicker specimen showed higher transmittance, presumably due to less crystallinity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.131-134
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• 2001

Vertically aligned carbon nanotubes are grown on iron-deposited silicon oxide substrates by thermal chemical vapor deposition of acetylene gas at the temperature range 750∼950$^{\circ}C$. As the growth temperature increases from 750 to 950$^{\circ}C$, the growth rate increases by 4 times and the average diameter also increases from 30 nm to 130 nm while the density increases progresively with the growth temperature and a higher degree of crystalline perfection can be achieved at 950$^{\circ}C$. This result demonstrates that the growth rate, diameter, density, and crystallinity of carbon nanotubes can be controlled with the growth temperature.

• Journal of Powder Materials
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• v.15 no.6
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• pp.489-495
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• 2008

Colored tantalum oxy-nitride (TaON) and tantalum nitride ($Ta_{3}N_{5}$) were synthesized by ammonolysis. Oxygen deficient tantalum oxides ($TaO_{1.7}$) were produced by a titration process, using a tantalum chloride ($TaCl_5$) precursor. The stirring speed and the amount of $NH_{4}OH$ were important factors for controling the crystallinity of tantalum oxides. The high crystallinity of tantalum oxides improved the degree of nitridation which was related to the color value. Synthesized powders were characterized by XRD, SEM, TEM and Colorimeter.