• Journal of the Korean Society of Safety
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• v.20 no.4 s.72
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• pp.29-33
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• 2005

In this paper, reflectance and the dielectric characteristics for $P_2O_5-ZnO-BaO$ system and $SiO_2-ZnO-B_2O_3$ system have been investigated as a function of contents of $TiO_2$. The reflectance was decreased with increasing the contents of $TiO_2$ and the reflectance of $P_2O_5-ZnO-BaO$ system was lowered than that of $SiO_2-ZnO-B_2O_3$ system. The dielectric constant of $P_2O_5-ZnO-BaO$ system was higher than $SiO_2-ZnO-B_2O_3$ system, and the dielectric constant in the both system was increased with increasing of $TiO_2$ contents. This can be explained as the space charge effects. These results are could be applied to the under plate dielectrics of PDP required high reflective ratio and breakdown strength.

• Ocean and Polar Research
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• v.26 no.2
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• pp.199-205
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• 2004

$SiO_2$ and CaO are added to decrease the smelting temperature in the reduction-smelting method for manganese nodule processing. These elements are components of the manganese nodules and might be very important controlling factors in the processing due to the locally variable content. The 707 chemical data of manganese nodules acquired from 1994 to 2001 in KODOS(Korea Deep Ocean Survey) area were used for the hierarchical cluster analysis. The chemical data were classified by the morphological types, and the averages of the chemical data for each station were classified by the facies groups and the localities. All data are plotted on the $SiO_2-CaO-MnO$ phase diagram at $1773^{\circ}K$ to compare with the best compositional area in the nodule smelting. Variations and distributions of $SiO_2$ and CaO in KODOS nodules were also reviewed. The mineral phases assigned by the cluster analysis are CFA(Carbonate Fluorapatite), Fe-oxide, Al-silicate, and Mn-oxide. MnO contents are generally higher than $SiO_2$ contents in most of the morphological types except for the Is- and It-type. The Dt- and Tt-type show wider range and the E-types show high anomaly in their CaO contents. The stations which belong to facies group A and B show generally higher MnO contents than $SiO_2$ contents, however, the stations of facies group C and D show wide range in their MnO and $SiO_2$ contents. It seems to be very important to control the $SiO_2$ contents in the processing because of the wide range in the northern area. The additions of approximately 10 wt.% CaO and 10 wt.% $SiO_2$ are recommended for the northern area, whereas, the additions of approximately 10 wt.% CaO and 20 wt.% $SiO_2$ are recommended for the southern area.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.224-225
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• 2007

The Low dielectric properties of epoxy/Annealing $SiO_2$ composites using Annealing new material of nanosized amorphous particles were investigated as function frequency, temperature and filler contents composition. The dielectric constant decrease with increasing frequency and also increase with increasing ambient temperature. The dielectric constant decrease with increase annealing filler contents for epoxy base. The result of x-ray diffraction could obtained single crystal of annealing $SiO_2$ from 500nm amorphous $SiO_2$ powder.

• 전자공학회논문지 IE
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• v.43 no.4
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• pp.8-12
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• 2006

In this paper, reflectance and the dielectric characteristics for $P_2O_5$-ZnO-BaO system and $SiO_2-ZnO-B_2O_3$ system have been investigated as a function of contents of $TiO_2$. The reflectance was decreased with increasing the contents of $TiO_2$ contents, and the reflectance of $P_2O_5$-ZnO-BaO system was lowered than that of $SiO_2-ZnO-B_2O_3$ system. The dielectric constant of $P_2O_5$-ZnO-BaO system was higher than $SiO_2-ZnO-B_2O_3$ system, and the dielectric constant in the both system was increased with increasing of $TiO_2$ contents. This can explained as the space charge effects. These results are could be applied to the lower dielectrics layer of PDP required high reflective ratio and breakdown strength.

• Korean Journal of Materials Research
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• v.14 no.1
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• pp.67-72
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• 2004

The glass-forming conditions are investigated in the $K_2$O-CaO-$SiO_2$ $-P_2$$O_{5}$ system with 10~65 mole% of$ P_2$$O_{5}$. Thermal properties and dissolution properties were investigated according to variation of the SiO and KO contents in selected compositions. The glass formation condition was determined when $K_2$O/$P_2$$O_{5}$ mole ratio 0~0.24, $SiO_2$/($SiO_2$+$P_2$$O_{5}$ ) mole ratio 0～0.29, and CaO/$P_2$$O_{5}$ mole ratio 0~1.00. In the result of the thermal properties, the glass transition temperature($T_{g}$) and softening temperature($T_{s}$ ) were gradually shifted to the lower temperature range with increase of $K_2$O contents. The maximum value of the chemical durability was shown in $K_2$$PO_2$$O_{5}$ mole ratio 0.17 when the $SiO_2$ contents were changed, and $K_2$O was fixed at 10 mole%. Hence the change of the $K_2$O/$P_2$$O_{5}$ mole ratio was found that a new main factor of the chemical durability.

• Journal of Conservation Science
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• v.33 no.3
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• pp.215-223
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• 2017

The purpose of this study is to reveal the characteristics, correlations, and colorant materials of those using the chemical compositions of 30 glasses excavated from the Sarari hall of the Mireuksaji stone pagoda, and to determine the correlations between them and other glass excavated from the Wanggungri site. The results of the chemical analysis of the 11 glass beads show that they are a soda glass group with high contents of $SiO_2$ and $Na_2O$; these can be further subdivided into soda-alumina groups ($Na_2O-Al_2O_3-CaO-Si_2O$). The characteristics of the stabilizer are classified as being of the high alumina glass group (LCHA), except for two glasses. It was concluded that colorant materials affected the coloring for glass beads by various components including Ti, Mn, Fe, Cu and Pb. In addition, we examined six lead glasses which are glass plate and unknown fragments that are of a common lead glass system ($PbO-SiO_2$) with respect to the average contents of PbO (70wt.%) and $SiO_2$ (30wt.%). As a result of comparing these relics with those of the glass beads excavated by Wanggungri, there is a similarity in that they belong to the soda glass group. However, the contents of $Na_2O$ are relatively higher than that of the glass beads in the Mireuksaji pagoda, and most of relics include glasses with a low content of $K_2O$ and CaO. In addition, the PbO and $SiO_2$ contents are slightly different in the lead glass. It seems that the glass relics made at two different sites may have used different raw materials or techniques.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.853-855
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• 1998

The electrical resistivity and mechanical properties of the hot-pressed and annealed ${\beta}$-SiC+39vol.%$ZrB_2$ electroconductive ceramic composites were investigated as a function of the liquid forming additives of $Al_{2}O_{3}+Y_{2}O_{3}$(6:4wt%). In this microstructures. no reactions were observed between $\beta$-SiC and $ZrB_2$, and the relative density is over 97.6% of the theoretical density. Phase analysis of composites by XRD revealed mostly of a $\alpha$-SiC(6H, 4H), $ZrB_2$ and weakly $\beta$-SiC(15R) phase. The fracture toughness decreased with increased $Al_{2}O_{3}+Y_{2}O_{3}$ contents and showed the highest for composite added with 4wt% $Al_{2}O_{3}+Y_{2}O_{3}$ additives. The electrical resistivity increased with increased $Al_{2}O_{3}+Y_{2}O_{3}$ contents because of the increasing tendency of pore formation according to amount of liquid forming additives $Al_{2}O_{3}+Y_{2}O_{3}$. The electrical resistivity of composites is all positive temperature coefficient resistance(PTCR) against temperature up to $700^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.36 no.10
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• pp.1087-1093
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• 1999

Bioglass which is one of the surface active bionmaterials has a good biocompatibility but a poor mechanical strength, In the present work therefore two types of fluoride-containing bioglasses were coated on an alumina to improve mechanical strength. Crystallization of the coating layer and the hydroxyapatite formation on the bioactive glass coatings in tris-buffer solution were studied. When bioactive glass coated alumina was heat-treated Na2CaSi3O8 crystal was formed on the layer at lower temperature while wollastonite(CaSIO3) was obtained at higher temperature. Hydroxyapatite forming rate on the coating layer with Na2CaSi3O8 crystal was delayed with SiO2 contents in glass composition. However the hydroxyapatite was developed in 20minutes regardless SiO2 contents when the coating layer crystallized into wollastonite. More amount of P3+ ions were leached out of the coating layer with wollastonite than that with Na2CaSi3O8 crystal while Na+ and Ca2+ ions were leached out more easily from the Na2CaSi3O8 crystal containing coating layer.

• Korean Journal of Materials Research
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• v.30 no.11
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• pp.621-626
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• 2020

This study is aimed at preparing and evaluating the plasma resistance of YAS (Y₂O₃-Al₂O₃-SiO₂) coating layer with crystalline YAG phase contents. For this purpose, YAS frits with controlled phase contents are prepared and melt-coated on sintered Al₂O₃ ceramics. Then, the results of phase analysis of crystalline YAS coating layer are compared to that of YAS frits, and discussed with regard to the plasma resistance of the YAS coating layer. The phase contents of the YAS frit change in a manner different from that of the prepared YAS coating layer, presumably owing to the composition change of YAS frit during the melt-coating process. The plasma resistance of the YAS coating layer is shown to increase with the YAG phase contents in the coating layer. Comparing the weight loss of YAS coating layer with those of commercial Y₂O₃, Al₂O₃, and quartz ceramics, the plasma resistance of the prepared YAS coating layer is 8 times higher than that of quartz and 3 times higher than that of Al₂O₃; this layer shows 70 % of the resistance of Y₂O₃.

• Horticultural Science & Technology
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• v.30 no.3
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• pp.250-255
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• 2012

The effect of different source silicon ($CaSiO_3$, $K_2SiO_3$, and $NaSiO_3$) and their application methods (foliar application and subirrigation) on the growth of potted kalanchoe was investigated. Rooted terminal cuttings of Kalanchoe blossfeldiana 'Peperu' were transplanted into 10.5 cm plastic pots containing a commercial growing medium. Then, a nutrient solution, containing 0 or $50mg{\cdot}L^{-1}$ Si as $K_2SiO_3$, $Na_2SiO_3$, or $CaSiO_3$ and adjusted to EC 1.4-$1.6mS{\cdot}cm^{-1}$ and pH 6.0, was supplied through subirrigation along with the nutrient solution or by a foliar application. Plants were grown in a glasshouse under a mean temperature of $23^{\circ}C$ and RH of 70-80%. After 12 weeks of cultivation, plant growth characteristics and leaf tissue contents of P, K, Ca, Mg, Na, S, and Si were measured. Both subirrigational supply and foliar application of Si decreased the plant height and flower stem length. However, the plant condition in the foliar application resulted in disease-like soft rot on the leaf. Among three silicon sources tested, $CaSiO_3$ supplied through a subirrigation system increased shoot tissue contents of Si and chlorophyll as compared to the $Na_2SiO_3$ or $K_2SiO_3$ treatment. Shoot tissue contents of Ca, K, and Na increased when the plant was supplied with $CaSiO_3$, $K_2SiO_3$, and $Na_2SiO_3$, respectively. Subirrigational supply of $K_2SiO_3$ and $NaSiO_3$ decreased the shoot tissue contents of Ca and Mg, and K and Ca, respectively. Therefore, $CaSiO_3$ supplied through a subirrigation system could improve plant quality of kalanchoe 'Peperu' making compact potted plants.