• Journal of the Korean Wood Science and Technology
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• 제22권3호
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• pp.26-31
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• 1994

To provide further information for reutilization of the waste wood obtained after cultivating oak mushroom in Kangwon-do, the crystal structures of the waste wood were investigated and compared to those of normal woods by a series of x-ray diffraction analysis. The results obtained are as follows: 1. An x-ray diffraction diagram of cultivated wood for 5 years was same as that of typical cellulose with some orientation of cellulose crystallites, but that of cultivated wood for 8 years a random. 2. Crystallinity indices in normal and cultivated woods for 5 years ranged from 57% to 60%. In the cultivated wood for 8 years, however, the value showed about 40%. 3. Crystallite widths of cultivated woods for 5 years and for 8 years were 3 nm and 2.5 nm, respectively. 4. Intensity ratios of equatorial and meridional layers did not show any significant differences. From the above results, it is clear that the waste wood obtained after cultivating oak mush room for 5 years showed basically same crystal structures with normal wood. Therefore, we think that the waste wood may be used available for cellulosic material instead of normal wood.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.1
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• pp.43-49
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• 2006

The surface and pore structure of cellulose fibers have a significant impact on the properties and performance in applications. Cellulase enzymatic hydrolysis of cellulose fibers can result in changes to the surface and pore structure thus providing a useful tool for fiber modification. This research characterizes these changes using various test methods such as fiber dimension, water retention value, hard-to-remove water content, freezing and non-freezing bound water content, polymer adsorption, and crystallinity index. For a high-dosage enzyme treatment (0.10 g/g), the fiber length was significantly decreased and the fibers were 'cut' in the cross direction, not in the axial direction. The swelling capacities as measured by the WRV and HR water content increased for the high-dosage treatment. Three independent measurements (non-freezing bound water, polymer adsorption, and crystallinity index) are in good agreement with the statement that the amorphous regions of cellulose fibers are a more readily available substrate relative to crystalline regions. Based on the experimental results obtained herein, a model was proposed to explain surface and pore structure modification of cellulose fibers via enzymatic treatment.

• Macromolecular Research
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• 제17권7호
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• pp.476-482
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• 2009

The crystallization behavior of poly(vinyl alcohol) (PVA) in the presence and absence of polypyrrole nanoparticles (PPy NPs) was investigated in terms of the heterogeneous nucleation effect of PPy NPs using FTIR, X-ray diffraction, differential scanning calorimeter and polarized optical microscope analysis. PPy NPs were prepared by dispersion polymerization method stabilized by PVA in aqueous solution. A polymer nanocomposite with uniform dispersity could be readily obtained due to the enhanced compatibility between the filler and matrix. Compared with the PPy NP-absent PVA, the PPy NP/PVA nanocomposite exhibited an enhanced degree of crystallinity. The degree of crystallinity increased up to 17% at the PPy NP concentration of 1 wt%, compared to the pristine PVA. The PPy NP acted as an effective nucleating agent during the crystallization process, thereby enhancing the degree and rate of crystallization. The kinetics study of the crystallization also revealed the decreased value of the Avrami coefficient in the case of the PPy NP/PVA nanocomposite.

• 한국입자에어로졸학회지
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• 제11권3호
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• pp.87-92
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• 2015

MCM-41 (Mobil Composition of Matter) and SBA-15 (Santa Barbara Amorphous) were used as a supported catalyst for ethylene polymerization due to their combination of large surface area and wide range of pore size distribution. The morphology of supports was used to control the morphology of the resulting polymer. Different molar ratios of Al/Ti were used for ethylene polymerization at $60^{\circ}C$ under atmospheric pressure. The effect of different mass ratios of MCM-41/SBA-15 and 1-hexene concentration on polymerization activity and polymer properties was investigated. The catalytic activity and the crystallinity reached the highest value at Al/Ti of 480. Upon incorporation of MCM-41 and SBA-15 into $MgCl_2/TiCl_4$ catalyst, the molecular weight and crystallinity of polyethylene were enhanced. The obtained polyethylene showed melting temperature between 130 and $135^{\circ}C$. The polyethylene with replication structure of support and bimodal MWD was expected.

• 센서학회지
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• 제28권4호
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• pp.256-261
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• 2019

In this study, mid-infrared transparent zinc sulfide (ZnS) ceramics were fabricated through hydrothermal synthesis with different molar ratios of S/Zn (S/Zn = 0.8, 1.0, 1.2, 1.4, and 1.6). The ZnS ceramics were sintered at a relatively low temperature of $850^{\circ}C$ to prevent the occurrence of the hexagonal phase featuring optical anisotropy. The phase composition, microstructure, and optical properties of the ZnS ceramics were subsequently investigated by employing X-ray diffraction, scanning electron microscopy, and Fouriertransform infrared spectroscopy. The results obtained indicate that the ZnS nanoparticles feature the cubic phase, without the hexagonal phase. Moreover, with increasing S, the crystallinity and particle size of the ZnS nanoparticles increased. The crystallinity and density of the ZnS ceramics improved when the molar ratio of S was higher than the molar ratio of Zn, thereby enhancing the transmittance. Furthermore, the ZnS ceramic with an S/Zn value of 1.2 was found to exhibit the highest transmittance of approximately 69% owing to the reduced occurrence of the hexagonal phase and a high density of 99.8%.

• Journal of the Korean Wood Science and Technology
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• 제50권5호
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• pp.353-364
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• 2022

The crystalline domain of thermosetting urea-formaldehyde (UF) resins at low formaldehyde-to-urea (F/U) molar ratios (≤ 1.0) is known to be responsible for their poor performance as wood adhesives. Crystallization has been observed in 1.0 F/U UF resins during the addition reaction stage and at the end of the synthesis process (neat UF resins). The crystallinity and X-ray diffraction (XRD) spectra of the uncured neat UF resins, on the other hand, differed significantly from those of the cured neat UF resins, raising the possibility that their crystal structures were also different. This study demonstrates for the first time that the crystalline domains in 1.0 F/U UF resins generated from uncured and cured samples are identical. Despite having a lower crystallinity value, the synchrotron XRD patterns of purified neat UF resins were equivalent to the XRD patterns of cured neat UF resins. Transmission electron microscope images of the cured UF resins showed that the crystals were lamellar structures. This finding suggests that the crystal at low molar ratio UF resins are isotropic polycrystals with random orientation.

• 한국포장학회지
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• 제10권1호
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• pp.7-14
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• 2004

Migration behavior of selected solvents and food samples showed differences of the chemical structures and polarities, the food samples which have similar polar expresses more higher affinity than different polar degrees. Water which is polar has a highest partitioning coefficient values on polar isopropanol, and oil which is nonpolar has highest partitioning value on non-polar toluene. The increasing order of partitioning values was accord with increasing water contents in food samples. It is showed that the wheat flour with 13.2% moisture content has the highest partitioning coefficient values on the isopropanol with -OH. Kp value of sugar showed remarkable lower partitioning coefficient values than other food samples due to high degree crystallinity. This phenomenon can be predictable with ${\delta}$ values, because order of partitioning coefficient values which comes out through the experiment and the sequence of Hildebrand solubility parameter value difference between food sample and printing ink solvent correspond almost. This Hildebrand solubility parameter value can be easily applied to the food package industry because the effect of food-safety can be considered without passing through complicated steps by using this method.

• Carbon letters
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• 제10권1호
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• pp.38-42
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• 2009

This study aims to find a correlation between XRD and Raman result of the oxidized high modulus carbon fibers as a function of its oxidation degrees, and compare with the isotropic carbon fiber reported early. La of the high modulus carbon fiber prepared by oxidation in carbon dioxide gas have been observed using laser Raman spectroscopy. The basic structural parameters of the fibers were evaluated by XRD as well. The La of the original high modulus carbon fibers were measured to be 144 ${\AA}$ from Raman analysis and 135 ${\AA}$ from XRD analysis. La of the 92% oxidized fiber were 168 ${\AA}$ by using Raman and 182 ${\AA}$ by using XRD. There was some correlation between the La value obtained from Raman and XRD. However the La value changes of the high modulus carbon fiber through whole oxidation process showed opposite tendency compare with the isotropic carbon fiber because of the fiber structure basically.

• 전기학회논문지P
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• 제58권4호
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• pp.538-540
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• 2009

The SBN thin films were deposited at substrate temperature of 300[$^{\circ}C$] on Pt-coated electrode (Pt/Ti/$SiO_2$/Si(100)) using RF sputtering method. The grain and crystallinity of SBN thin films were increased with the increase of annealing temperature. The dielectric constant(150) of SBN thin film was obtained by annealing temperature above 750[$^{\circ}C$]. The voltage dependence of dielectric loss showed a value within 0.01 in voltage ranges of -5~+5[V]. The capacitance characteristics showed a stable value of about 0.7[${\mu}F/cm^2$].

• 한국재료학회지
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• 제27권5호
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• pp.242-247
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• 2017

ZnO film was prepared on a p-type Si wafer and then annealed at various temperatures in air and vacuum conditions to research the electrical properties and bonding structures during the annealing processes. ZnO film annealed in atmosphere formed a crystal structure owing to the suppression of oxygen vacancies: however, ZnO annealed in vacuum had an amorphous structure after annealing because of the increment of the content of oxygen vacancies. Schottky contact was observed for the ZnO annealed in an air. O 1s spectra with amorphous structure was found to have a value of 529 eV; that with a crystal structure was found to have a value of 531.5 eV. However, it was observed in these results that the correlation between the electronic characteristics and the bonding structures was weak.