• Journal of the Korean Wood Science and Technology
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• 제20권1호
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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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• 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.

• 한국광물학회지
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• 제21권2호
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• pp.201-208
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• 2008

최근 기능성 나노물질로서 반도체 공정 중 기계.화학적 평탄화(CMP)용 연마제로 중요하게 사용되는 세리아(Ceria, $CeO_2$)에 대해서 X-선 회절분석을 실시하여 리트벨트법에 의한 상세한 구조해석 및 세리아의 입자크기와 미세응력을 측정하였다. 두 시료(RT735. RT835)의 리트벨트 계산 결과 R지수 값은 각각 $R_p(%)=8.50$, 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, 1.2를 보여주며 계산이 잘 이루어졌음을 알 수 있다. $CeO_2$는 공간군 Fm3m을 가지며, 격자상수는 a=5.41074(2), 5.41130(6) ${\AA}$, V=158.406(1), 158.455(3) ${\AA}^3$으로 각각 계산되었다. 입자크기 및 미세응력 계산 결과, RT735의 평균 입자크기와 최대 응력은 37.42(1) nm, 0.0026이며, RT835는 72.80(2) nm, 0.0013으로 각각 결정되었다. 입자크기와 미세응력은 서로 반비례함을 알 수 있다.

• Advances in nano research
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• 제16권1호
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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.

• 한국군사과학기술학회지
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• 제6권3호
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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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• 제36권4호
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• pp.11-18
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• 2008

국내 간척지에서 생장한 양마(kenaf)의 생장특성을 이해하기 위하여 전보(이 등, 2007)와 동일한 시료를 이용하여 생장기간과 높이에 따른 조직 및 구성 세포의 비율, 섬유 길이 및 도관 직경을 광학현미경을 이용하여 측정하였다. 또한, 세포벽 중의 셀룰로오스 상대결정화도와 결정 폭을 X선회절법으로 측정하였다. 양마의 구성 비율은 사부 10~15%, 목부 66~82%, 수 7~19% 정도였는데, 줄기 높이와 생장기간에 따른 차이를 보였다. 사부내에서는 사부방사조직이 약 50%, 인피섬유가 약 20%, 피층, 사관 등 기타 요소가 30% 정도인 것으로 나타났다. 반면, 목부의 구성 비율은 목부섬유가 약 75%, 방사조직이 약 15%, 도관이 약 10%를 차지하였다. 양마목부의 세포벽 비율은 기부 30.92%, 최상부 46.40%로 최상부가 기부보다 높게 나타났다. 인피섬유의 길이는 줄기 기부에서 약 2.8 mm이고 높이가 증가할수록 감소되며 생장기간이 길어지면 다소 증가하는 경향을 보인 반면, 목부섬유 길이는 생장기간과 줄기 높이에 관계없이 약 0.9 mm의 안정된 값을 나타내었다. 도관의 방사 및 접선방향 직경은 생장기간이 길어질수록 증가하였고, 줄기 높이가 높아질수록 감소하였다. 상대결정화도는 사부에서 70~79%, 목부에서 50~56%로 사부가 높았고, 줄기 기부가 상부보다 다소 높게 나타났다. 셀룰로오스 결정 폭은 사부와 목부에서 약 3 nm로 거의 차이가 없었다. 결론적으로 각 조직과 조직 구성 요소의 비율 및 세포의 치수는 양마의 줄기 높이와 생장기간에 따라 차이를 보였지만 셀룰로오스의 결정구조는 차이가 없는 것으로 확인되었다.