• Membrane and Water Treatment
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• 제8권5호
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• pp.437-448
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• 2017

A high quality Na-X zeolite membrane was synthesized on a seeded ${\alpha}-alumina$ disc by the secondary growth method. Structural characterization was done by X-ray spectroscopy, FT-IR spectroscopy, SEM and AFM imaging. The performance evaluation of the membrane was firstly tested in separation of glucose/water solutions by pervaporation process. There was obtained a separation factor $182.7{\pm}8.8$, while the flux through the membrane was $3.6{\pm}0.3kg\;m^{-2}\;h^{-1}$. The zeolite membrane was then used for desalination of aqueous solutions consisting of $Na^+$, $Ca^{2+}$, $Cs^+$ and $Sr^{2+}$ because of the importance of these ions in water and wastewater treatments. The effects of some parameters such as temperature and solution concentration on the desalination process were studied for investigating of diffusion/adsorption mechanism in membrane separation. Finally, high water fluxes ranged from 2 up to $9kg\;m^{-2}\;h^{-1}$ were obtained and the rejection factors were resulted more than 95% for $Na^+$ and $Ca^{2+}$ and near to 99% for $Cs^+$ and $Sr^{2+}$. Based on the results, fluxes were significantly improved due to convenient passage of water molecules from large pores of NaX, while the fouling was declining dramatically. Based on the results, NaX zeolite can efficiently use for the removal of different cations from wastewaters.

• Transactions on Electrical and Electronic Materials
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• 제7권6호
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• pp.283-292
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• 2006

So that high-strength and electrical properties apply by excellent high voltage insulator electricity material, ATH content and platinum-based flame retardant that influence in flame retardant and tracking characteristic among composite of silicone rubber studied mechanical strength and influence getting to electrical properties. Composition of ${\alpha}$, ${\omega}-vinyl$ poly (dimethyl-methylphenyl) siloxane(VPMPS) of a polymer quantity made doing mole of D4, $D3^{Me,Ph}$ and VMS by 1000:15:0.2 mole ratio and uses basic catalyst tetramethylammonium silanolate(TMAS) and do opening equilibrium polymerization to be used to main polymer for high voltage insulation insulator. Control ATH content and content of platinum-based flame retardant and made high voltage insulation silicone rubber. Measured mechanical strength of making silicone rubber using UTM, and tracking characteristic according to standard of IEC 60587, flame retardant test studied effect that flame retardant characteristic gets in tracking characteristic, measuring according to UL94V method of test.

• 한국전기전자재료학회논문지
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• 제22권9호
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• pp.776-780
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• 2009

In this study, the opto-electric properties of EL devices with PMN dielectric layer with variation of firing tempereature were investigated. For the PMN dielectric layer process, the paste was prepared by optimization of quantitative mixing of PMN powder, $BaTiO_3$, Glass Frit, $\alpha$-Terpineol and ethyl cellulose. The EL device stack consists of Alumina substrate ($Al_2O_3$), metallic electrode (Au), insulating layer (manufactured PMN paste), phosphor layer (ELPP- 030, ELK) and transparent electrode (ITO), which is well structure as a thick film EL device. The phase transformation properties of PMN dielectric with various firing temperatures of $150^{\circ}C$ to $850^{\circ}C$ was characterized by XRD. Also the opto-electric properties of EL devices with different firing temperature were investigated by LCR meter and spectrometer. We found the best opto-electric property was obtained at the condition of $550^{\circ}C$ firing which is 3432.96 $cd/m^2$ at 1948.3 pF Capacitance, 40 kHz Frequency, 40% Duty, Vth+330 V voltage.

• Membrane and Water Treatment
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• 제10권5호
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• pp.353-360
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• 2019

ZSM-5 membrane was prepared on tubular macroporous ${\alpha}$-alumina support using a different synthesis route. The effects of organic template agent and Si/Al ratio of the synthesis gel on morphology, structure, and separation performance of the ZSM-5 membrane used for dehydration of isopropanol were investigated. High water perm-selectivity ZSM-5 membrane with a thickness of about $3.0{\mu}m$ and a low Si/Al ratio of 10.1 was successfully prepared from organotemplate-free synthesis gel with a molar composition of $SiO_2$ : $0.050Al_2O_3$ : $0.21Na_2O$ : NaF : $51.6H_2O$ at $175^{\circ}C$ for 24 h. The ZSM-5 membrane exhibited high pervaporation performance with a flux of $3.92kg/(m^2{\cdot}h)$ and corresponding separation factor of higher than 10,000 for dehydration of 90 wt.% isopropanol/water mixture at $75^{\circ}C$.

• 멤브레인
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• 제25권5호
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• pp.422-430
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• 2015

본 연구에서는 silicalite-1 제올라이트 분리막 합성 시에 종결정 코팅용액 pH 변화가 제올라이트 분리층 미세구조에 미치는 영항을 고찰하였다. 75 nm 크기로 합성된 종결정은 에탄올에 분산된 후 침지코팅법으로 지지체 표면에 코팅되었으며 분산용액의 pH는 2.2, 7.0, 9.3으로 조절되었다. pH가 7인 경우, 균일하고 두께가 $3{\sim}4{\mu}m$인 silicalite-1 제올라이트 분리층이 형성되었고 분리층 결정입 크기는 100 nm로 미세하였다. 반면, pH가 2.2와 9.3인 경우, 분리층 두께가 얇고 불완전하였으며 분리층 결정입 크기도 약 $1{\mu}m$로 조대하였다. pH 7에서 완전한 제올라이트 분리층이 형성된 것은 침지코팅 중에 지지체와 종결정이 서로 다른 부호의 전하를 가져 정전기적 인력이 작용하여 균일하고 조밀하며 두껍고 다층의 종결정 코팅층이 형성되었기 때문이었다. 반면에 pH가 2.2와 9.3인 경우, 침지코팅 중에 지지체와 종결정이 서로 같은 부호의 전하를 가져 정전기적 반발력이 작용하기 때문에 불완전한 덮힘에 의하여 불완전한 분리층이 형성된다고 판단되었다. 결론적으로, 종결정 코팅용액의 pH가 silicalite-1 제올라이트 분리층의 두께, 결정립 크기 등 미세구조를 결정하는 중요한 인자임을 확인할 수 있었다.

• 센서학회지
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• 제8권2호
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• pp.195-201
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• 1999

$Al_2O_3$ (알루미나 및 R-면 사파이어)기판 위에 c-축 $YBa_2Cu_3O_{7-{\delta}}$ (YBCO) 박막을 펄스레이저 증착법을 이용하여 성장하였다. 완충층으로 사용하기 위해 $Al_2O_3$ 기판 위에 증착한 $CeO_2$ 박막의 결정성은 기판온도에 많은 영향을 받았다. $CeO_2$ 박막은 $800^{\circ}C$의 기판온도에서 $\alpha$-축방향으로 잘 성장하였으며, $CeO_2$ 완충층의 두께에 따라 YBCO/$CeO_2/Al_2O_3$ 박막의 초전도 특성은 큰 변화를 나타내었다. 알루미나 기판 위에서 $CeO_2$ 완충층의 두께는 약 $1200\;{\AA}$이하, 사파이어 기판의 경우 $100{\sim}1000\;{\AA}$ 범위에서 YBCO 박막은 양호한 초전도 특성을 나타내었으나, 그 보다 두껍게 성장시킬 경우 초전도 특성이 급격하게 나빠졌다. 알루미나 기판 위에 성장된 YBCO 박막의 임계온도는 83 K였으며, R-면 사파이어 기판 위에 성장된 YBCO 박막의 임계온도는 ${\geq}89.5\;K$였고, 임계전류밀도는 77K에서 $3{\times}10^6\;A/cm^2$로 나타났다.

• The Journal of Advanced Prosthodontics
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• 제3권1호
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• pp.16-19
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• 2011

PURPOSE. Purpose of this study was to evaluate effect of two surface treatments, sandblasting and monomer treatment, on tensile bond strength between two long term resilient liners and poly (methyl methacrylate) denture base resin. MATERIALS AND METHODS. Two resilient liners Super-Soft and Molloplast-B were selected. Sixty acrylic resin (Trevalon) specimens with cross sectional area of $10{\times}10$ mm were prepared and divided into two groups of 30 specimens each. Each group was surface treated (n = 10) by sandblasting (250 ${\mu}$ alumina particles), monomer treatment (for 180 sec) and control (no surface treatment). Resilient liners were processed between 2 poly(methyl methacrylate) surfaces, in the dimensions of $10{\times}10{\times}3$ mm. Tensile strength was determined with Instron Universal testing machine, at a crosshead speed of 5 mm/min; and the modes of failure (adhesive, cohesive or mixed) were recorded. The data were analyzed using one-way ANOVA, followed by Tukey HSD test (${\alpha}$= 0.05). RESULTS. Monomer pretreatment of acrylic resin produced significantly higher bond strengths when compared to sandblasting and control for both resilient liners (P < .001). Sandblasting significantly decreased the bond strength for both the liners when compared to monomer pretreatment and control (P < .001). Mean bond strength of Super-Soft lined specimens was significantly higher than Molloplast-B in various surface treatment groups (P < .05). CONCLUSION. Surface pretreatment of the acrylic resin with monomer prior to resilient liner application is an effective method to increase bond strength between the base and soft liner. Sandblasting, on the contrary, is not recommended as it weakens the bond between the two.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.942-945
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• 2003

Nerve gas sensor based on tin oxide was fabricated and its characteristics were examined. Target gas was dimethylmethylphosphonate($C_3H_9O_3P$, DMMP) that is simulant gas of nerve gas. Sensing material was $SnO_2$ added ${\alpha}-Al_2O_3$ with $4{\sim}20wt.%$ and was physically mixed. And then it was deposited by screen printing method on alumina substrate. Sensor device was consisted of sensing electrode with interdigit(IDT) type in front and heater in back side. Total size of device was $7{\times}10{\times}0.6mm^3$. Crystallite size of fabricated $SnO_2$ were characterized by X-ray diffraction(XRD, Rigaku) and morphology of the $SnO_2$ powders was observed by a scanning electron microscope(SEM, Hitachi). Fabricated sensor was measured as flow type and sensor resistance change was monitored real time using LabVIEW program. The best conditions as added $Al_2O_3$ amounts and operating temperature changes were 4wt.% and $300^{\circ}C$ in DMMP 0.5ppm, respectively. The sensitivity was over 75%. Response and recovery times were about 1 and 3 min., respectively. Repetition measurement was very good with ${\pm}3%$ in full scale.

• Preventive Nutrition and Food Science
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• 제16권1호
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• pp.55-61
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• 2011

A survey aiming to find out the chemical and textural properties of commercial fermented soy bean curd called sufu was conducted. Sixteen brands of plain sufu produced in the Northern or the Southern part of China were collected and examined for their crude protein, crude fat, texture profiles, free amino acids, and free fatty acid contents. Twenty-one free amino acids were extracted and derivatized using a commercial kit followed by separation and analyzed by the gas chromatography-mass spectrometry (GC-MS). Similarly, ten free fatty acids were extracted using alumina, eluted, separated and analyzed. The content ranges of crude fat and protein were 22~36% and 31~38%, respectively. In texture profile analysis, ranges of the texture parameters were 131~493 g (hardness), 0.4~0.5 (cohesiveness), -137 to -50 gs (adhesiveness), 0.6~1 (springiness), 47~220 g (gumminess) and 32~177 g (chewiness). Twenty-one different free amino acids, especially alanine, glycine, $\alpha$-aminobutyric acid, valine, leucine, allo-isoleucine, aspartic acid, glutamic acid and lysine in large amount, as well as ten fatty acids in total, notably linoleic acid (9-octadecanoic acid), oleic acid (9,12-octadecadienoic acid), linolenic acid (9,12,15-octadecadienoic acid), hexadecanoic acid and octadecanoic acid were found. This information provides important quality reference ranges for product developers and manufacturers to optimize and produce the plain sufu.

• 대한치과교정학회지
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• 제45권1호
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• pp.29-37
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• 2015

Objective: The coefficients of friction (COFs) of aesthetic ceramic and stainless steel brackets used in conjunction with stainless steel archwires were investigated using a modified linear tribometer and special computer software, and the effects of the bracket slot size (0.018 inches [in] or 0.022 in) and materials (ceramic or metal) on the COF were determined. Methods: Four types of ceramic (one with a stainless steel slot) and one conventional stainless steel bracket were tested with two types of archwire sizes: a $0.017{\times}0.025$-in wire in the 0.018-in slots and a $0.019{\times}0.025$-in wire in the 0.022-in slot brackets. For pairwise comparisons between the 0.018-in and 0.022-in slot sizes in the same bracket, an independent sample t-test was used. One-way and two-way analysis of variance (ANOVA) and Tukey's post-hoc test at the 95% confidence level (${\alpha}$ = 0.05) were also used for statistical analyses. Results: There were significant differences between the 0.022-in and 0.018-in slot sizes for the same brand of bracket. ANOVA also showed that both slot size and bracket slot material had significant effects on COF values (p < 0.001). The ceramic bracket with a 0.022-in stainless steel slot showed the lowest mean COF (${\mu}$ = 0.18), followed by the conventional stainless steel bracket with a 0.022-in slot (${\mu}$ = 0.21). The monocrystalline alumina ceramic bracket with a 0.018-in slot had the highest COF (${\mu}$ = 0.85). Conclusions: Brackets with stainless steel slots exhibit lower COFs than ceramic slot brackets. All brackets show lower COFs as the slot size increases.