• Journal of the Korean Wood Science and Technology
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• v.48 no.6
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• pp.896-906
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• 2020

Wood deterioration experiments were carried out for 6 months in an intertidal zone of South Korea to monitor the changes in the chemical properties of two types of species, Korean red pine and sawtooth oak. The results of FT-IR spectra and XRD patterns have shown that the chemical properties of the wood did not change significantly during the 6-month burial period. However, the brightness of the surface decreased after burial; the value of the sawtooth oak sample was lower than that of the Korean red pine sample owing to an accumulation of inorganic compounds in cell lumen as observed by ICP analysis. Among the inorganic compounds, sodium and sulfur concentrations increased significantly over the burial period compared with the control. Further, the maximum moisture content decreased from 199% to 136% in the Korean red pine and 62% to 60% for the sawtooth oak. Nevertheless, the major chemical composition of both the wood species did not change significantly during the 6-month burial period, whereas, the crystallinity decreased with an increasing burial period owing to an accumulation of inorganic compounds in the lumen.

• Journal of the Korean Ceramic Society
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• v.31 no.10
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• pp.1159-1168
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• 1994

We powders were synthesized from W powders in differnet particle sizes by Self-propagating High-temperature Synthesis process (SHS) using a chemical furnace. The effects of the mole ratio of chemical fuel content, pellet thickness and the mole ratio between carbon and tungsten (C/W Ratio) on synthesis were investigated with the tungsten powders have different particle size each other. Compositional and structural characterization of these powders was carried out by scanning electron microscope (SEM0 and x-ray diffractometer. Powder characterization was carried out by the measurement of particle size distribution with laser-particle size analyzer. The amounts of WC obtained by SHS process depend very much on the particle size of tungsten powder and heat contents given in a product, i.e. as the particle size of W powder is smaller, the amounts of WC produced increase. Also the more heat contents is given, the more amounts of WC increase. By optimizing the synthesis conditions, it is possible to fabricate WC powders which have little secondary phases (W2C, C).

• Korean Chemical Engineering Research
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• v.46 no.2
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• pp.310-315
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• 2008

Organic-inorganic hybrid solutions were made using glycidoxypropyl trimethoxysilane (GPTMS) and vinyltriethoxysilane (VTES) as starting materials by sol-gel method. Photochromic coating solutions were prepared by mixing the solution of photochromic dye (spiropyran) dissolved in ethylacetate with the organic-inorganic hybrid solutions. Photochromic films were prepared on polycarbonate sheets by spin coating and cured for 2 h at $100^{\circ}C$. The resulting films exhibited a reversible color change upon irradiation with UV light from transparent to blue. The color-fading speed and pencil hardness of the coating films increased with increasing the GPTMS content in the coating solutions.

• Korean Journal of Organic Agriculture
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• v.21 no.1
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• pp.61-68
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• 2013

This study was conducted to evaluate overwintering of hairy vetch (Vicia villosa Roth), biomass, and inorganic N concentration in soil to verify the adaptability of eight cultivars of hairy vetch into country. Winter survival rate was higher for the hairy vetch cultivars, such as Hungvillosa or Ostsaat, than those of Minnie, Oregon common, and TTF1, which affected amount of biomass of each hairy vetch, with higher biomass observed in Hungvillosa or Ostsaat cultivar. There were no significant difference for the mineral nutrients of each hairy vetch cultivar. Inorganic N concentration in soil was increased at 10 days after mowing by application of Hungvillosa and Ostsaat cultivars that had highly produced N content from the raw materials.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.4
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• pp.371-376
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• 1999

A large NaX type zeolite crystal of a uniform particle size of 20$\mu\textrm{m}$ are grown with various {{{{{H}_{2}O}}}} content by hydrothermal reaction and added seed crystal (2~3$\mu\textrm{m}$) to reactant solution as a function of different adding seed levels from 3 to 15%. The result that increased purity of NaX zeolite above 95% and homogeneity of crystal size by increasing adding seed levels, also decreased crystallization time. It was explained that adding seed to synthesis solution leaded out increase of surface area for physical contact reaction and directed growth of seed crystal, so more rapid consumption of reaction gel as increase seeding levels.

• Polymer(Korea)
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• v.36 no.5
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• pp.662-667
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• 2012

Poly(ethylene terephthalate) (PET) base films with high light transmittance have been used for the substrate of various functional films in the flat panel display. The effects of the reflective index of coated films, the roughness of the film surface and the content of inorganic silica particles on the light transmittance were studied in this article. Light transmittance was increased by coating a water soluble resin with a low reflective index at an optimum thickness. The roughness of the film did not affect light transmittance when the Ra of the film surface was less than a quarter of the wavelength of incident light. Inorganic silica particles decreased light transmittance due to their absorbance and scattering of the incident light.

• Bulletin of the Korean Chemical Society
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• v.23 no.6
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• pp.884-890
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• 2002

An inorganic-organic hybrid system, silica-poly(ethylene glycol) songel is reported. This system was prepared via sol-gel method by varying varous processing variables. e.g. ultrasonic radiation time, gelling temperanture, PEG content and its molecular weight. Various experimental techniques wee employed to analyze the morphological, mechanical and optical properties of the system. The results were discussed in the light of existing theories. The sonogel system exhibited the common features of inorganic-organic hybrids. $SiO_2-10$ wt% PEG sonogel exhibited the morphological and optical properties superior to those reported earlier for the classic gels and found suitable for device applications.

• The Korean Journal of Ceramics
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• v.3 no.1
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• pp.47-51
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• 1997

The dense sintered bodies of Si/SiC composite with various Si contents could be fabricated by changing the green density in the forming process. The Si/SiC/graphite composites with various graphite contents could be also fabricated by changing a graphite content in the starting composition. Their mechanical and tribological properties were characterized and wear mechanism was also studided. The hardness and strength of the Si/SiC and the Si/SiC/graphite were decreased with increasing the contents of free Si and graphite, respectively. However, the friction coefficient and specific wear rate had no specific relations to their hardness and strength. Adhesion of free Si was a main factor to determine a wear resistance of the Si/SiC composite. In the case of the Si/SiC/graphite, solid lubricationl and liquid reservoir of the graphite particles played the main role of the reduction of the friction force. In the torque test to estimate the possibility of practical of practical applications, the value of torque between the Al2O3 disk and Si/SiC/graphite disk was 1/6 lower compared with two $Al_2O_3$ disks on the basis of 100,000 cycles.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.112-117
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• 2008

Organic-inorganic hybrid solutions were prepared via sol-gel method using glycidoxypropyl trimethoxysilane (GPTMS) and methyl triethoxysilane (MTES) as starting precursors at a molar ratio of 1:1. The photochromic coating solutions were prepared by mixing the solutions of photochromic dye (spiropyran) dissolved in ethylacetate (EA) with the organic-inorganic hybrid solutions. Photochromic films were prepared on polycarbonate substrate by spin coating and cured for 2 h at $100^{\circ}C$. The resulting films exhibited a reversible color change upon irradiation with UV light. The photochromic properties of the films showed that the color-fading speed increases with increasing the EA content in the coating solutions.

• Composites Research
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• v.35 no.5
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• pp.359-364
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• 2022

Polymers are inherently vulnerable to flame, which limits their application to various high-tech industries. In addition, environmental regulations restrict the use of halogen-based flame retardants which has best flame-retardant effect. There are inorganic flame retardants and phosphorous flame retardants as representative non-halogen-based flame retardants. However, high content of flame retardants is required to impart high flame retardancy of the polymers, and this leads to a decrease in mechanical properties. In this research, a new approach for inorganic flame retardant-based polymer composites with high mechanical properties and flame retardancy was suggested. Inorganic flame retardants called as magnesium oxysulfate whisker (MOSw) were used in this research. MOSw can extinguish fire by releasing water and non-combustible gases when exposed to flame. In addition, they have reinforcing effect when added into the polymer with its high aspect ratio. Expandable graphite (EG) was used as a flame-retardant supplement by helping to form a more dense char layer. Through this research, it is expected that it can be applied to various industries requiring flame retardancy such as automobile, and architecture by replacing halogen-based flame polymer composites.