• Journal of the Korean Crystal Growth and Crystal Technology
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• v.3 no.1
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• pp.31-36
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• 1993

Na-Fe Tourmalene ($NaFe_3Al_6B_3Si_6O_{27}F_4$)single crystals were grown by FZ method. The Growth conditions are counter rotation 20~30rpm, growth rate 1~5mm/hr in the atmospheric environment. The transition elements as Fe(in this research), Mn, Co, etc, are exist in the theoretical fomulae so that dopants were not added. The feed rod was sintered between $1000^{\circ}C$ and $1l00^{\circ}C$, but at higher temperature, it was difficult to manufacture the feed rod because of evaporation of the elements such as F. As grown crystals had a black color and the length of 50~60mm, the diameter of 5~6mm. X-ray powder diffraction pattern indicated that the composition of the feed rod was right to the Tourmaline composition. By FT-IR spectra, the state of bonding of each element was charaterized.

• Membrane Journal
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• v.18 no.1
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• pp.103-107
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• 2008

Membrane process has been focused as an alternative separation process because not only it exhibits a high selectivity compared with a traditional distillation process, but also it is known to be an energy saving separation process. Inorganic membrane, especially zeolite membrane, has been studied since it can be operated in severe conditions compared to the organic membranes. Recently, new zeolite materials are tested as an inorganic membrane material to overcome disadvantages of existing zeolite membranes. Kalsilite can be used as an inorganic membrane material for gas separation and selective water separation from water/organic mixtures because it is expected to be hydrophilic resulted from Si/Al ratio of 1 like zeolite 4A and has a narrow pore size of 0.36 nm. In this study, kalsilite was synthesized by a new economical hydrothermal process using Si : Al : K : $H_2O$ mole ratio of 1 : 1 : 8 : 60. The synthesized kalsilite powder was confirmed by XRD and has a mean diameter of $2.73{\mu}m$. The vapor adsorption test showed the synthesized kalsilite is hydrophilic.

• Korean Journal of Materials Research
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• v.4 no.1
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• pp.31-36
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• 1994

The bonding behavior of $SiO_{2}$ thin film and glass during VCR head fabrication was investigated, varying the surface roughness of substrate and the sputtering parameter. Insufficient fillings of grooves In the $SiO_{2}$ film with glass was postulated to give rise to the generation of bubble in the glass. The surface roughness of $SiO_{2}$ film was found to depend on that of substrate. The lower the deposition rate, the smoother the surface of film. The bubble free glass after bonding could be obtained using substrate polished with 0.05$\mu\textrm{m}$ $Al_2O_3$ powder under the sputtering condition of 10% oxygen pressure.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.498-506
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• 2019

This study is based on a coating method that provides utilization value as a micronised powder for cosmetic raw materials using natural minerals buried in Bonghwa, Gyeongsangbuk-do in Korea. The mineral powder name is called Buseok, and chemical name is pumice powder. The results of a study on the efficacy of cosmetics are reported by the development of particulate powder to assess the performance of this powder. First of all, in order to coat the surface of this powder with oil, aluminum hydroxide was coated on the particulate surface and then coated with alkylsilan. In addition, it was coated with vegetable oil to prevent condensation of the powder and increase the dispersion in the oil phase. First; the particle size of pumice powder was from 10 to 50mm having porous holes on the surface of the particles. Second; The components of this powder contained $SiO_2$, $Al_2O_3$, $Fe_2O_3$, MgO, CaO, $K_2O_2$, $Na_2O$, $TiO_2$, $TiO_2$, MnO, $Cr_2O_3$, $V_2O_5$. Third: The particles of this powder have a planetary structure and are reddish-brown with porosity through SEM and TEM analysis. Fourth; the far-infrared radiation rate of this parabolic powder was $0.924{\mu}m$, and the radiative energy was $3.72{\times}102W/m^2$ and ${\mu}m$. In addition, the anion emission is 128 ION/cc, which shows that the coating remains unchanged. Based on these results, it is expected to be widely applied to basic cosmetics such as BB cream, cushion foundation, powderfect, and other color-coordinated cosmetics, sunblock cream, wash-off massage pack as an application of cosmetics. (Small and Medium Business Administration: S2601385)

• Journal of Powder Materials
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• v.16 no.5
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• pp.316-325
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• 2009

Fe based (Fe$_{68.2}$C$_{5.9}$Si$_{3.5}$B$_{6.7}$P$_{9.6}$Cr$_{2.1}$Mo$_{2.0}$Al$_{2.0}$) amorphous powder, which is a composition of iron blast cast slag, were produced by a gas atomization process, and sequently mixed with ductile Cu powder by a mechanical ball milling process. The experiment results show that the as-prepared Fe amorphous powders less than 90 $\mu$m in size has a fully amorphous phase and its weight fraction was about 73.7%. The as-atomized amorphous Fe powders had a complete spherical shape with very clean surface. Differential scanning calorimetric results of the as-atomized Fe powders less than 90 $\mu$m showed that the glass transition, T$_g$, onset crystallization, T$_x$, and super-cooled liquid range $\Delta$T=T$_x$-T$_g$ were 512, 548 and 36$^{\circ}C$, respectively. Fe amorphous powders were mixed and deformed well with 10 wt.% Cu by using AGO-2 high energy ball mill under 500 rpm.

• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3289-3293
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• 2014

Femtosecond laser ablation (fs LA) was used in this study to identify pollution by heavy metals and the distribution of elemental nutrients at different rice milling ratios. Polished rice (degrees of milling of 3, 5, 7, 9, and 11) was collected from major Korean supermarkets and one sample thereof was selected. An internal quality control experiment was conducted using a rice flour certified reference material from the Korea Research Institute of Standards and Science (KRISS CRM) for the evaluation of the efficacy. To assess the effectiveness of the analysis method, the reliability was validated using a food analysis performance assessment scheme (FAPAS), with chili powder serving as an external quality control. The results of the analysis of the inorganic elements Ti, Ca, Al, Fe and Mn in white and brown rice with degrees of milling of 3, 5, 7, 9 and 11 using ICP-MS, ICP-OES and AAS revealed contents of 0.40, 49.2, 2.43, 5.36 and 10.3 mg/kg in white rice and 0.59, 78.0, 7.52, 11.0 and 18.5 mg/kg in brown rice, respectively. Among the elements, there were remarkable differences in the measured contents. By comparing the contents of the elements at different degrees of milling, Ti, Co, As, Ca, Al, Cu, Fe, and Mn were determined to be distributed on the surface of the rice grains, whereas the contents of Cd and Pb increased toward the center of the rice grains, and Si was evenly distributed. After the quantitative analysis of rice samples polished to different degrees of milling, Ca and Al, which were contained in large amounts, and Si were analyzed with specificity by fs LA. The results show that Ca and Al were distributed in the rice husk (protective covering of rice) and Si was distributed in all parts of the rice.

• Journal of the Microelectronics and Packaging Society
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• v.8 no.2
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• pp.31-36
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• 2001

Teflon-like fluorocarbon thin film was deposited by using difluoromethane$(CH_2F_2$) added with Ar, $O_2$, and $CH_4$ on Si, $SiO_2$, TEOS, and Al substrate. The deposited thin film was characterized by static contact angles for measuring hydrophobicity in various additive gas ratio. temperature, and working pressure. In case of addition with Ar, the static contact angles decreased as additive gas ratio and power increased. But the static contact angles increased as working pressure increased. Specially, super-hydrophobic surface was obtained using the powder-like fluorocarbon thin film above 2 Torr. Added with $O_2$, the static contact angles decreased as the $O_2$ ratio and working pressure increased. And the static contact angles did not change in 100W, but hydrophilic surface was obtained at 200W. In case of addition of CE$_4$, static contact angles dramatically increased in $CH_4/CH_2F_2$ ratio 5. And continuous static contact angles obtained above ratio 5. As compare with previous experiments by thermal evaporation, the fluorocarbon thin film by plasma polymerization was obtained very low hysteresis. This results shows more homogenous surface by plasma polymerization than thermal evaporation process.

• Clean Technology
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• v.27 no.4
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• pp.359-366
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• 2021

Halloysite nanotubes (HNTs), the multiwalled clay mineral with the composition of Al₂Si₂O₅(OH)₄·nH₂O, have been highlighted as a low-cost adsorbent for the removal of dyes from wastewater. Although a powder of halloysite presents a high specific surface area, forming media are significantly considered due to sludge-clogging induced by the water-bound agglomeration. However, higher firing temperature to achieve the structural durability of the media and lower utilization rate due to longer penetration depth into the media act as hurdles to increase the dye-adsorption capacity. In this work, the retention of the adsorption capacity of halloysite was evaluated with methylene blue solution after the heat treatment at 750 ℃. In order to improve the utilization rate, tubular media were fabricated by extrusion. The images taken by transmission electron microscopy show that HNTs present excellent structural stability under heat treatment. The HNTs also provide superb capacity retention for MB adsorption (93%, 18.5 mg g^-1), while the diatomite and Magnesol^® XL show 22% (7.65 mg g^-1) and 6% (11.7 mg g^-1), respectively. Additionally, compositing with lignin enhances adsorption capacity, and the heat treatment under the hydrogen atmosphere accelerates the adsorption in the early stage. Compared to the rod-type, the tubular halloysite media rapidly increases methylene blue adsorption capacity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.5
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• pp.455-462
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• 2000

The objective of this study was to examine the physicochemical characteristics of coagulation reaction between loess and red tide organisms (RTO) and its feasibility, in developing a technology for the removal of RTO bloom in coastal sea. The physicochemical characteristics of loess were examined for a particle size distribution, surface characteristics by scanning electron microscope, zeta potential, and alkalinity and pH variations in sea water. Two kinds of RTO that were used in this study, Cylindrothen closterium and Skeietonema costatum, were sampled in Masan bay and were cultured in laboratory. Coagulation experiments were conducted using various concentrations of loess, RTO, and a jar tester. The supernatant and RTO culture solution were analyzed for pH, alkalinity, RTO cell number. A negative zeta potential of loess increased with increasing pH at $10^(-3)M$ NaCl solution and had -71.3 mV at pH 9.36. Loess had a positive zeta potential of +1,8 mV at pH 1.98, which resulted in a characteristic of material having an amphoteric surface charge. In NaCl and $CaCl_2$, solutions, loess had a decreasing negative zeta potential with increasing $Na^+\;and\;Ca^(+2)$ ion concentration and then didn't result in a charge reversal due to not occurring specific adsorption for $Na^+$ ion while resulted in a charge reversal due to occurring specific adsorption for $Ca^(+2)$ ion. In sea water, loess and RTO showed the similar zeta potential values of -112,1 and -9.2 mV, respectively and sea sand powder showed the highest zeta potential value of -25.7 mV in the clays. EDLs (electrical double-layers) of loess and RTO were extremely compressed due to high concentration of salts included in sea water, As a result, there didn't almost exist EDL repulsive force between loess and RTO approaching each other and then LVDW (London-yan der Waals) attractive force was always larger than EDL repulsive force to easily form a floe. Removal rates of RTO exponentially increased with increasing a loess concentration. The removal rates steeply increased until $800 mg/l$ of loess, and reached $100{\%}$ at 6,400 mg/l of loess. Removal rates of RTO exponentially increased with increasing a G-value. This indicated that mixing (i.e., collision among particles) was very important for a coagulation reaction. Loess showed the highest RTO removal rates in the clays.