• Advances in environmental research
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• 제6권4호
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• pp.255-264
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• 2017

This work investigated the use of sugarcane bagasse ash (SCBA) generated by an energy cogeneration process in sugarcane mill as an alternative raw material in soil-cement brick. The SCBA obtained from a sugarcane mill located in southeastern Brazil was characterized with respect to its chemical composition, organic matter content, X-ray diffraction, plasticity, and pozzolonic activity. Soil-cement bricks were prepared by pressing and curing. Later, they were tested to determine technical properties (e.g., volumetric shrinkage, apparent density, water absorption, and compressive strength), present crystalline phases, and microstructural evolution. It was found that the SCBA contains appreciable amounts of silica ($SiO_2$) and organic matter. The results showed that the SCBA could be used in soil-cement bricks, in the range up to 30 wt.%, as a partial replacement for Portland cement. These results suggest that the SCBA could be valorized for manufacturing low-cost soil-cement bricks.

• 한국재료학회지
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• 제17권6호
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• pp.303-307
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• 2007

ZnO thin films were prepared by pulsed laser deposition on amorphous fused silica substrates at different ambient $O_2$ pressures varying from 0.5 to 500 mTorr, to observe the effect of ambient gas on their crystalline structure, morphology and optical properties. Results of X-ray diffraction, scanning electron microscopy, atomic force microscopy and photoluminescence studies showed that crystallinity, surface features and optical properties of the films significantly depended on the oxygen background pressure during growth. A low oxygen pressure (0.5 mTorr) seems to be suitable for the growth of highly c-axis oriented and smoother films possessing a superior luminescent property. The films grown at the higher $O_2$ pressures (50-500 mTorr) were found to have many defects probably due to an excessive incorporation of oxygen into ZnO lattice. We speculate that the film crystallinity could be affected by the kinetics of atomic arrangement during deposition at the higher oxygen pressures.

• 한국세라믹학회지
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• 제37권2호
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• pp.174-180
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• 2000

Y-TZP/mullite composites were prepared by the infiltration of Y-TZP precursor into partially reaction-sintered mullite. The addition of Y-TZP(~7.2 wt%) increased the bend strength(207 MPa), fracture toughness(4.6MPa.m1/2) and Vickers microhardness(853kg/$\textrm{mm}^2$) of the uninfiltrated mullite sintered at 162$0^{\circ}C$ for 10h by more than 75, 70 and 105%, respectively. Residual alumina-rich glass was observed at a mullite/mullite junction, due to the mullitization reaction of silica melt with crystalline $\alpha$-Al2O3 during a final sintering. Although ZrO2 inclusions improved the final sintered density of mullite they did not effectively prevent its grain growth.

• 한국세라믹학회지
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• 제30권1호
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• pp.41-45
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• 1993

synthesis of artificial kaolinite and the transformation of domestic halloysite have been attempted by means of the hydrothermal treatment. The hydrothermal reaction of the mixtures of gibbsite and amorphous silica was conducted for the synthesis of kaolinite under the pressure of 125MPa at 30$0^{\circ}C$ and especially the seed of kaolinite was added so as to facilitate the synthesis reaction. Domestic pink kaolin of B-grade was hydrothermally treated, in a similar way, for the transformation of crystalline form of it. Boehmite and the artificial kaolinite less than 0.4${\mu}{\textrm}{m}$ could be obtained through the hydrothermal reaction. It could also be found that the majority of hyalloysite was transformed into the plate-type kaolinite through the recrystallization by treating hydrothermally for a long time.

• 생약학회지
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• 제4권4호
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• pp.167-172
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• 1973

Five crystalline substances, which are positive to$L_{IEBERMAN}-B_{URCHARD}$ reaction, were isolated from the unsaponifiable fraction of the fresh leaves of Betula latifolia $K_{OMAROV}$ (Betulaceae)by silica gel column chromatographic purification. Compound $A\;(C_{29}H_{50}O,\;mp\;136^{\circ}), \;B\;(C_{30}H_{52}O_3,\;mp\;165^{\circ}), \;C\;(C_{30}H_{52}O_4,\;mp\;237^{\circ}), \;D\;(C_{30}H_{52}O_3,\;mp\;196^{\circ})\;and\; E\;(C_{30}H_{52}O_4,\;mp\;121^{\circ})$ were isolated. Compound B was characterized as a new tetracyclic triterpenoid. Compounds A, C and D were identified as ${\beta}-sitosterol$, betulatriterpene C, and betulafolienetriol, respectively.

• 생약학회지
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• 제4권4호
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• pp.189-190
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• 1973

Silica gel column chromatography on the ether extract from the fruits of Angelica gigas $M_{AKAI}$ gave two kinds of crystalline constituents. The following derivatives of coumarins were identified by IR, NMR spectra, elemental analysis and physico-chemical tests: iso-imperatorin $(mp\;108{\sim}109^{\circ},\;C_{16}H_{14}O_4)$ and decursidin $(mp\;60{\sim}61^{\circ},\;C_{24}H_{26}O_7)$.

• 생약학회지
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• 제4권4호
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• pp.191-192
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• 1973

Silica gel column chromatography of the ether extract of the root of Angelica decursiva $F_{RANCHET}\;et\;S_{AVATIER}$ form. albiflora $N_{AKAI}$ (Umbelliferae) gave four kinds of crystalline products of pyranocoumarin and furocoumarin: decursidin $(mp\;60{\sim}61^{\circ},\;C_{24}H_{26}O_7)$, decursin$(mp\;110{\sim}111^{\circ},\;C_{19}H_{20}O_5)$, umbelliferone $(mp\;227{\sim}228^{\circ},\;C_{9}H_{6}O_3)$, and nodakenetin $(mp\;187{\sim}189^{\circ},\;C_{14}H_{14}O_4)$. Besides, the methanol extract of the root was found to contain sucrose.

• 생약학회지
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• 제2호2호
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• pp.87-88
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• 1971

Silica gel column chromatography on the ether extract from the fruits of Angelica tenuissima $N_{AKAI}$ gave three kinds of crystalline constituents. The following derivatives of furocoumarins and steroid were identified by UV, IR, NMR spectra, elemental analysis and physico-chemical tests: iso-imperatorin m.p. $108{\sim}109^{\circ}\;C_{16}H_{14}O_4$, prangolarine m.p. $103{\sim}104^{\circ}\;C_{16}H_{14}O_5$, ${\beta}-sitosterol$ m.p. $138{\sim}139^{\circ}\;C_{29}H_{50}O$.

• 약학회지
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• 제12권3_4호
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• pp.59-64
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• 1968

Silica gel column chromatography of the ether extract of the root of Angelica Koreana $M_{AXIMOWICZ}$ (Umbelliferae) gave five kinds of crystalline products of coumarin. The following kinds of furocoumarins were identified by UV, IR, NMR spectra and physico-chemical tests. iso-imperatorin m.p. 108-$109^{\circ}$ $C_{16}H_{14}O_{4}$ oxypeucedanin m.p. 142-$143^{\circ}$ $C_{16}H_{14}O_{5}$ prangolarine m.p. 104-$105^{\circ}$ $C_{16}H_{14}O_{5}$ imperatorin m.p. 100-$101^{\circ}$ $C_{16}H_{14}O_{4}$ These analyses also showed that white needles m.p. 129-$130^{\circ}$ were likely to be a furocoumarin. Besides, the methanol extract of the root was found to contain sucrose.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.725-727
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• 2009

Lowering the dielectric constant is one of the important issues for the efficiency and the power consumption in the plasma display panel (PDP) industry. This study examined the effect of the addition of ceramic filler (up to 10% of crystalline and amorphous silica, respectively) to a $B_2O_3$-ZnO- $P_2O_5$ glass matrix on the dielectric, coefficient of thermal expansion, etching behaviors and residual stress for the barrier ribs in plasma display panels. The dielectric constant of barrier ribs is affected by containing two types of $SiO_2$ filler for the barrier rib composition in PDP.