• Title/Summary/Keyword: Na-Si

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Dielectric Relaxation Properties of KNN-BT Ceramics with (Ba,Ca)SiO3 Glass Frit ((Ba,Ca)SiO3 Glass Frit 첨가에 따른 NKN-BT 세라믹스의 유전 완화 특성)

  • Bae, Seon Gi;Shin, Hyeo-Kyung;Lee, Seung-Hwan;Im, In-Ho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.27 no.6
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    • pp.367-371
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    • 2014
  • We investigated dielectric relaxation properties of $0.95(Na_{0.5}K_{0.5})NbO_3-0.05BaTiO_3$ ceramics by addition (0~0.3 wt%) of $(Ba,Ca)SiO_3$ glass frit. All composition of $0.95(Na_{0.5}K_{0.5})NbO_3-0.05BaTiO_3$ added $(Ba,Ca)SiO_3$ glass frit showed the same crystallographic properties, coexistence of orthorhombic and tetragonal phase. By increasing addition of $(Ba,Ca)SiO_3$ glass frit, the Curie temperatures of $0.95(Na_{0.5}K_{0.5})NbO_3-0.05BaTiO_3$ ceramics were decreased, whereas maximum dielectric constants of $0.95(Na_{0.5}K_{0.5})NbO_3-0.05BaTiO_3$ ceramics were dramatically increased. Especially the deviations of Curie temperature $0.95(Na_{0.5}K_{0.5})NbO_3-0.05BaTiO_3$ ceramics were increased by increasing amount of $(Ba,Ca)SiO_3$ glass frit, and it indicated that $0.95(Na_{0.5}K_{0.5})NbO_3-0.05BaTiO_3$ ceramics added $(Ba,Ca)SiO_3$ glass frit have relaxor characteristics.

The Effect of Co2+-Ion Exchange Time into Zeolite Y (FAU, Si/Al = 1.56): Their Single-Crystal Structures

  • Seo, Sung Man;Kim, Hu Sik;Chung, Dong Yong;Suh, Jeong Min;Lim, Woo Taik
    • Bulletin of the Korean Chemical Society
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    • v.35 no.1
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    • pp.243-249
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    • 2014
  • Three single crystals of fully dehydrated $Co^{2+}$-exchanged zeolite Y (Si/Al = 1.56) were prepared by the exchange of $Na_{75}$-Y ($|Na_{75}|[Si_{117}Al_{75}O_{384}]$-FAU) with aqueous streams 0.05 M in $Co(NO_3)_2$, pH = 5.1, at 294 K for 6 h, 12 h, and 18 h, respectively, followed by vacuum dehydration at 673 K. Their single-crystal structures were determined by synchrotron X-ray diffraction techniques in the cubic space group Fd3m at 100(1) K. They were refined to the final error indices $R_1/wR_2$ = 0.0437/0.1165, 0.0450/0.1228, and 0.0469/0.1278, respectively. Their unit-cell formulas are $|Co_{29.1}Na_{11.8}H_{5.0}|[Si_{117}Al_{75}O_{384}]$-FAU, $|Co_{29.8}Na_{11.0}H_{4.4}|[Si_{117}Al_{75}O_{384}]$-FAU, and $|Co_{30.3}Na_{9.5}H_{4.9}|[Si_{117}Al_{75}O_{384}]$-FAU, respectively. In all three crystals, $Co^{2+}$ ions occupy sites I, I' and II; $Na^+$ ions are also at site II. The tendency of $Co^{2+}$ exchange slightly increases with increasing contact time as $Na^+$ content and the unit cell constant of the zeolite framework decrease.

Verification for the Validity and Reliability of the Type D Scale-14 (D 유형 성격 측정 도구의 타당도와 신뢰도 검증)

  • Son, Haeng-Mi
    • Journal of Korean Academy of Fundamentals of Nursing
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    • v.15 no.3
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    • pp.312-320
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    • 2008
  • Purpose: The purpose of this study was to verify the validity and reliability of the Type D Scale-14 (DS14). Methods: The participants were 288 patients who were diagnosed with angina pectoris, myocardial infarction, and hypertension. DS14 was developed by Denollet(2005) and consists of two domains, 7 items on negative affectivity (NA) and 7 items on social inhibition (SI). The Korean version of DS14 was developed through translation-reversed translation and a preliminary test. Data were collected using a self-report questionnaire. Cronbach $\alpha$ and Guttman split-half were used to test reliability and item analysis and factor analysis for validity. The SPSS program was used. Results: 35.8% of the participants were classified as Type D. Mean score for NA was 16.80 and for SI, 14.10 in Type D participants. For reliability of NA, Cronbach $\alpha$=0.771, and for SI, 0.707. Factor analysis on 12 items(numbers 1 & 3 were excluded as the corrected item-total correlations were below r=0.3) yielded two factors for NA (6 items) and SI (6 items). Number 7 in the NA domain was sorted into the SI domain. Conclusion: The results indicate, the cultural differences were between Europeans and Koreans. Repetition of the research is needed for generalization of DS14.

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Dry Media Reaction Procedure for Synthesis of α,β-Unsaturated Acids, α-Cyanoacrylonitriles and α-Cyanoacrylates via Knoevenagel Condensation Using NaHSO4·SiO2 Catalyst (NaHSO4·SiO2 촉매를 이용한 Knoevenagel 축합을 거친α,β의 불포화산, α-Cyanoacrylonitriles와 α-Cyanoacrylates의 합성을 위한 무수조건하의 반응 절차)

  • Gopalakrishnan, M.;Sureshkumar, P.;Kanagarajan, V.;Thanusu, J.;Thirunavukkarasu, S.
    • Journal of the Korean Chemical Society
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    • v.51 no.4
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    • pp.346-351
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    • 2007
  • Efficient stereoselective synthesis of α,β-Unsaturated acids, α-Cyanoacrylonitriles and α-Cyanoacrylates has been carried out in the presence of NaHSO4·SiO2 under solvent?free conditions with an E-geometry.

Flowing and Strength Properties of Ternary System Inorganic Composite According to the Change of W/B and Addition Ratio of Na2SiO3 (3성분계 무기결합재의 W/B 및 규산나트륨 첨가율 변화에 따른 유동 및 강도특성)

  • Bae, Sang-Woo;Moon, Ji-Hwan;Lee, Yun-Seong;Lee, Kang-Pil;Lee, Sang-Soo;Song, Ha-Young
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2011.11a
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    • pp.49-50
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    • 2011
  • This study tried to utilize basic data for developing the cement substitute material through ternary system inorganic composite properties of flowing and strength. W/B and addition ratio of Na2SiO3 have been changed in ternary system inorganic composite combined blast furnace slag, red mud and fly ash. As to the experimental result inorganic composite, the flowing and intensity improvement effect was showed to be bigger than W/B according to the addition ratio change of the Na2SiO3. When particularly the Na2SiO3 addition ratio was 6%, the rapid flowing and strength improvement effect was confirmed.

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NaHSO4/SiO2: An Efficient Catalyst for the Synthesis of β-Enaminones and 2-Methylquinolin-4(1H)-Ones under Solvent-Free Condition (NaHSO4/SiO2: Solvent-Free 반응 조건에서 β-Enaminone들과 2-Methylquinolin-4(1H)-One들의 합성을 위한 효율적인 촉매)

  • Sapkal, Suryakant B.;Shelke, Kiran F.;Shingate, Bapurao B.;Shingare, Murlidhar S.
    • Journal of the Korean Chemical Society
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    • v.54 no.6
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    • pp.723-726
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    • 2010
  • An efficient and simplified protocol for $NaHSO_4/SiO_2$ catalyzed solvent-free synthesis of $\beta$-enaminone and 2-methylquinolin-4(1H)-one derivatives under microwave irradiation is described. A series of functionalized derivatives have been synthesized in shorter reaction times with moderate to good yields. The use of milder catalyst in non-conventional method offers significant advantages over conventional methods, such as higher selectivities, simplicity, solvent-free reaction and non-environmental polluting conditions.

A Facile Entry for One-pot Synthesis of 5,7-Diaryl-4,4-dimethyl-4,5,6,7-tetrahydropyridino[3,4-d]-1,2,3-selenadiazoles (5,7-Diaryl-4,4-dimethyl-4,5,6,7-tetrahydropyridino [3,4-d]-1,2,3-selenadiazoles의 손쉬운 One-pot 합성)

  • Gopalakrishnan, M.;Thanusu, J.;Kanagarajan, V.
    • Journal of the Korean Chemical Society
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    • v.52 no.1
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    • pp.47-51
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    • 2008
  • A simple synthetic strategy is described for one-pot synthesis of 5,7-diaryl-4,4-dimethyl-4,5,6,7-tetrahydropyridino[3,4-d]-1,2,3-selenadiazoles (11-15) in the presence of NaHSO4.SiO2 as a heterogeneous catalyst in dry media under microwave irradiation.Key words: One-pot synthesis, 3,3-Dimethyl-2,6-diarylpiperidin-4-one; 1,2,3-Selenadiazoles; Selenium dioxide; NaHSO4.SiO2 Heterogeneous catalyst.

Effects of Heat-treatment Condition on the Characteristics of Sintering and Electrical Behaviors of Two NASICON Compounds (열처리조건이 두 NASICON 조성의 소결 및 전기적특성에 미치는 영향)

  • 강희복;조남희;김윤호
    • Journal of the Korean Ceramic Society
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    • v.34 no.7
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    • pp.685-692
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    • 1997
  • Effects of sintering temperature and time on the phase formation, the characteristics of sintering and electrical behaviors of NASICON compounds with Na3Zr2Si2PO12 and Na3.2Zr1.3Si2.2P0.8O10.5 compositions synthesized by solid state reaction were investigated. Maximum relative densities of 96% and 91% were obtained for Na3Zr2Si2PO12 and Na3.2Zr1.3Si2.2P0.8O10.5 compounds, respectively. Complex impedance analysis in a frequency range below 4 MHz was performed to measure the ionic conductivity and migration barrier height of the compounds at RT-30$0^{\circ}C$. The maximum ionic conductivity and the minimum migration barrier height were 0.45 ohm-1cm-1 and 0.07 eV, respectively. The migration barrier height of the high temperature form (space group : R3c) is about 30-40% of that of the low temperature form (space group : C2/c) in two NASICON compounds. Ionic conductivity increases with increasing sinterability, and the presence of glass phase in Na3.2Zr1.3Si2.2P0.8O10.5 compounds lowers significantly ionic conductivity at temperatures above 14$0^{\circ}C$.

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Development of Alkaline Degreasing Agent for Electroplating Pretreatment Process (도금 전처리공정에서 맞춤형 알칼리계 탈지제 개발)

  • Lee, Seung-Bum;Joeng, Koo-Hyung;Lee, Jae-Dong
    • Applied Chemistry for Engineering
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    • v.21 no.3
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    • pp.301-305
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    • 2010
  • In this study, the alkaline degreasing agent was developed for electroplating pretreatment process, and the efficiency and the durability was predicted. The alkaline deeping degreasing agent was prepared by blending sodium hydroxide (NaOH), sodium carbonate ($Na_2CO_3$), sodium silicate ($Na_2SiO_3$), and sodium lauric sulfate (SLS). The performance tests of the degreasing agent were evaluated in the $40{\sim}50^{\circ}C$ of the degreasing temperature and 30~40 min of the degreasing time. The efficiency and durability of the prepared degreasing agent were tested by the waterdrop formation test and Hull-cell plating test. The optimum ratio of alkaline degreasing agent was NaOH (30 g/L) + SLS (6.0 g/L) + $Na_2SiO_3$ (2.0 g/L) + $Na_2CO_3$ (40 g/L). Also, the optimum degreasing conditions were $50^{\circ}C$ of the degreasing temperature and 35 min of the degreasing time.

Characterization and Bacteicidal Effect of Na_2O-Al_2O_3-SiO_2$ Glass System by $Na^+$$\longleftrightarrow$$Ag^+$ Ion Exchange ($Na^+$$\longleftrightarrow$$Ag^+$ 이온교환에 따른 Na_2O-Al_2O_3-SiO_2$ 계 유리의 특성 및 살균효과)

  • 이광희;최세영
    • Journal of the Korean Ceramic Society
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    • v.33 no.2
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    • pp.242-250
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    • 1996
  • Glasses of Na2O-Al2O3-SiO2 system were prepared and ion-exchange characteristics change of properties and bactericidal effects by Na+↔Ag+ ion exchange were studied. Parent glasses with three compositions of varying Na2O in the 20~30 wt% were ion-exchanged in the molten salt of 2 mol% AgNO3+98 mol% NaNO3 at 320~36$0^{\circ}C$ for 15~16min. Amount of ion exchange and penetration depth of Ag+ ion increased with Na2O content in the parent glass ion exchange temperature and time. After ion exchange densities and Vickers hardness of the glasses increased and the glasses showed yellow-brown color and as amount of ion exchange increased the color turned deep because partial reduction and agglomeration of Ag+ into Ag0 results in absorption of visible light. After ion exchange chemical durability of the glass to wter was enhanced compara-bly that weight loss and change of surface of the glass were not found for the leaching test in 5$0^{\circ}C$ K.I water for 240hrs. Bactericidal effect of ion exchanged glass on Staphylococcus aureus and E. coli was determined by microorganism test and bactericidal effect increased with amount of ion exchange and incubation time.

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