• Journal of the Korean Wood Science and Technology
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• v.20 no.1
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• pp.28-37
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• 1992

Fine structures of some Korean woods were investigated by X-ray diffraction methods. Relative crystallinity measured by the Segal's method and by the area method was $53{\pm}6%$ and $43{\pm}8%$ in softwoods, and $54{\pm}5%$ and $45{\pm}5%$ in hardwoods, respectively. The crystallite dimension in width was $3.11{\pm}0.45nm$ in softwoods and $3.22{\pm}0.25nm$ in hardwoods. In the longitudinal direction, the dimension was $12.79{\pm}0.89nm$ in softwoods and $12.60{\pm}0.72nm$ in hardwoods. The d-spacings of (200) in equatorial and (004) in meridional layers were about 0. 397 run and about. 0.260 nm, respectively. As a result, relative crystallinity, crystallite dimensions and d-spacings of (200) did not show any differences between the softwoods and hardwoods. The ratio of integrated intensities of (002) and (004), however, showed some differences between the softwoods and hardwoods. Namely, it was $0.101{\pm}0.027$ in softwoods and $0.138{\pm}0.037$ in hardwoods.

• Journal of the Korean Wood Science and Technology
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• v.22 no.3
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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.

• Journal of the Mineralogical Society of Korea
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• v.21 no.2
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• pp.201-208
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• 2008

Ceria ($CeO_2$) becomes one of important functional nanomaterials and a key abrasive material for chemical-mechanical planarization (CMP) of advanced integrated circuits in silicon semi-conductor technology. Two synthetic crystalline ceria (RT735, RT835) are studied by the Rietveld structural refinement to determine crystallite size and microstrain. Rietveld indices of RT735 and RT835 indicate good fitting with $R_p(%)=8.50$, 8.34; $R_{wp}(%)=13.4$, 13.5; $R_{exp}(%)=11.3$, 11.5; $R_B(%)=2.21$, 2.36; S(GofF: Goodness of fit)=1.2, 1.2, respectively. $CeO_2$ with space group Fm3m show a=5.41074(2), 5.41130(6) ${\AA}$, V=158.406(1), 158.455(3)${\AA}^3$ in dimension. Detailed Rietveld refinement reveals that crystallite size and microstrain are 37.42(1) nm, 0.0026 (RT735) and 72.80(2) nm, 0.0013 (RT835), respectively. It also shows that crystallite size and microstrain of ceria are inversely proportional to each other.

• Advances in nano research
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• v.16 no.1
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• pp.53-69
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• 2024

Advancements in the technology of building materials has led to diverse applications of nanomaterials with the aim to monitor concrete structures. While there are myriad instances of the use of nanoparticles in building materials, the production of smart nano cement-composites is often expensive. Thereupon, this research aims to discover a sustainable nanomaterial from tyre waste using the pyrolysis process as part of the green manufacturing circle. Here, Nano Structure Tyre-Char (NSTC) is introduced as a zero-dimension carbon-based nanoparticle. The NSTC particles were characterized using various standard characterization techniques. Several salient results for the NSTC particles were obtained using microscopic and spectroscopic techniques. The size of the particles as well as that of the agglomerates were reduced significantly using the milling process and the results were validated through a scanning electron microscope. The crystallite size and crystallinity were found to be ~35nm and 10.42%, respectively. The direct bandgap value of 5.93eV and good optical conductivity at 786 nm were obtained from the ultra violet visible spectroscopy measurements. The thermal analysis reveals the presence of a substantial amount of carbon, the rate of maximum weight loss, and the two stages of phase transformation. The FT-Raman confirms the presence of carboxyl groups and a ID/IG ratio of 0.83. Water contact angle around 140° on the surface implies the highly hydrophobic nature of the material and its low surface energy. This characteristic process assists to obtain a sustainable nanomaterial from waste tyres, contributing to the development of a smart building material.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.3
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• pp.54-61
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• 2003

$SnO_2$ gas sensor for the detection DMMP, simulant of nerve gas was fabricated and its characteristics were examined. Sensing materials were $SnO_2$ added by TEX>$\alpha$-$Al_{2}O_{3}$ with 0∼20wt.% and $In_{2}O_{3}$ with 0∼3wt.% and were physically mixed each material. They were deposited by screen printing method on alumina substrate. The sensor was consisted of sensing electrode with interdigit(IDT) type in front and a heater in back side. Its dimension was 7$\times$10$\times$0.6$\textrm{mm}^2$. Crystallite size 8t phase identification, specific surface area and morphology of fabricated $SnO_2$ powders were analyzed by X-ray diffraction(XRD), surface area analyzer(BET) and by a scanning electron microscope(SEM), respectively. Sensor was measured as flow type and sensor resistance change was monitored as real time using LabVIEW program. The best sensitivities were 75% at adding 4wt.% TEX>$\alpha$-$Al_{2}O_{3}$, operating temperature $300^{\circ}C$ and 87% at adding 2wt.% $In_{2}O_{3}$, operating temperature $350^{\circ}C$ to DMMP 0.5ppm. Response and recovery times were about 1 and 3 min., respectively. Repetition measurement was very good with $\pm$3% in full scale. As a result, operating temperature was lower TEX>$\alpha$-$Al_{2}O_{3}$ than $In_{2}O_{3}$, but sensitivity was higher $In_{2}O_{3}$ than $\alpha$-$Al_{2}O_{3}$.

• Journal of the Korean Wood Science and Technology
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• v.36 no.4
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• pp.11-18
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• 2008

Anatomical characteristics of volumetric composition, fiber length, vessel diameter, and crystalline properties of cellulose in kenaf (Hibiscus cannabinus L.) planted in the reclaimed land of Buan-si, Korea were examined to understand the growth characteristics using a light microscopy and an X-ray diffraction method. The samples of kenaf were taken from six positions (3 cm, 35 cm, 70 cm, 105 cm, 280 cm, and 320 cm) of each stem over the growth period (July, August, September, and October) after seeding in the mid-May. In the kenaf stem, phloem constituted 10 to 15 %, xylem 66 to 82%, and pith 7 to 19%. The ray, bast fiber, and remainder comprised 50%, 20%, and 30% of the phloem, respectively. The volume of vessel, ray, and fiber in the xylem was approximately 10, 15, and 75%, respectively. The proportion of cell wall was 30.92% at the base of stem and 46.40% at the top of stem, respectively. The average length of bast fiber and xylem fiber was about 2.8 mm and 0.9 mm, respectively. Radial and tangential diameters of vessel increased with the increase of growth period, while they decreased with increasing the stem height. Relative crystallinity ranged from 70 to 79% in phloem and from 50 to 56% in xylem. Cellulose crystallite width was about 3 nm both in the phloem and xylem. Thus, the volumetric composition and cell dimensions in the phloem and xylem appeared to be varied with the growth period and the stem height.