• 한국세라믹학회지
• /
• 제31권6호
• /
• pp.643-650
• /
• 1994

Highly [100]-oriented MgO thin films were deposited on Si(100) single crystal substrates by reactive RF magnetron sputtering. The effects of substrate temperature, gas pressure, RF input powder, and gas composition on the characteristics of MgO thin films were studied. The higher substrate temperature and the lower operating pressure were, the better crystallinity of the deposited MgO thin films were. The influences of the RF input power and oxygen to argon ratio were very complex. The physical characteristics of the films changed dramatically with deposition conditions. Highly smooth and epitaxial MgO films were obtained at the deposition conditions as follows; subatrate temperature, $600^{\circ}C$; operating pressure, 10 mtorr; RF input power density, 2 W/$\textrm{cm}^2$; the percentage of oxygen, 10%.

• Bulletin of the Korean Chemical Society
• /
• 제33권8호
• /
• pp.2483-2488
• /
• 2012

The X-ray line broadening technique was used to calculate the grain size of MgO at 1023, 1123, 1223 K respectively either in $CO_2$ or during the thermal decomposition of magnesites in air as well as in vacuum. By referring to the conventional grain growth equation, $D^n=kt$, the activation energy and pre-exponential factor for the process in air are gained as 125.8 kJ/mol and $1.56{\times}10^8\;nm^4/s$, respectively. Ranman spectroscopy was employed to study the surface structure of MgO obtained during calcination of magnesite, by which the mechanism of grain growth was analyzed and discussed. It is suggested that a kind of highly reactive MgO is produced during the thermal decomposition of magnesites, which is exactly the reason why the activation energy of the grain growth during the thermal decomposition of magnesite is lower than that of bulk diffusion or surface diffusion.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
• /
• pp.795-798
• /
• 2003

Inside of working PDP, there exist highly reactive conditions in the gap between two glass panels. MgO layer and phosphor have been investigated as a function of discharge and temperature. A drastic reduction in carbon impurity was observed on the surfaces after discharging and heat treatment. Carbon composition on the MgO and phosphor is a dominant factor for their instability

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
• /
• pp.495-498
• /
• 2004

PDP use the mixture of inert gases to generate a discharge inside display pixels. Inside of PDP, there exist highly reactive conditions in the gap between two glass panels. MgO layer and phosphor have been investigated as a function of discharge and thermal process. Impurities such as CO, $CO_2$, OH and $H_2O$ in discharge region may deteriorate the characteristics of PDP operation during life time. Change of impurity generation of various MgO and phosphor surfaces were measured by using x-ray photoelectron spectroscopy(XPS) and quadropole mass spectrometer (QMS). Carbon containing species such as C, CO and $CO_2$ were drastically increased on the surfaces during discharge and thermal treatment. Carbon impurities on the MgO and phosphor are the dominant factor for their instability.

• 한국세라믹학회지
• /
• 제54권4호
• /
• pp.303-307
• /
• 2017

Pure $In_2O_3$, 0.5 and 1.0 wt% Mg doped $In_2O_3$ hollow spheres were synthesized by ultrasonic spray pyrolysis of a solution containing In-, Mg-nitrate and sucrose and their gas sensing characteristics to 5 ppm $C_2H_5OH$, p-xylene, toluene, and HCHO were measured at 250, 300 and $350^{\circ}C$. Although the addition of Mg decreases the specific surface area and the volume of meso-pores, the gas response (resistance ratio) of the 0.5 wt% Mg doped $In_2O_3$ hollow spheres to 5 ppm $C_2H_5OH$ at $350^{\circ}C$ (69.4) was significantly higher than that of the pure $In_2O_3$ hollow spheres (24.4). In addition, the Mg doped $In_2O_3$ hollow spheres showed the highest selectivity to $C_2H_5OH$. This was attributed to the dehydrogenation of $C_2H_5OH$ assisted by basic MgO into reactive $CH_3CHO$ and $H_2$.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
• /
• pp.1199-1202
• /
• 2005

Inside of working PDP, there exist highly reactive conditions in the gap between two glass panels. MgO film and phosphor have been investigated as a function of discharge, also phosphor and sealing frits have been investigated as a function of temperature. Changes of impurity generation of MgO, phosphor and sealing fits were measured by using x-ray photoelectron spectroscopy (XPS) and quadropole mass spectroscopy (XPS) and quadropole mass spectrometer (QMS). Impurities such as CO, $CO_2$, OH and $H_2O$ were increased during discharge and heating treatment. Gaseous impurities such as carbon compounds and water deteriorated the characteristics of PDP operation during of lifetime. So metal is used to remove the impurities of phosphor and sealing frits during hearting, the result that the quantity of the impurities such as carbon monoxide and water was reduced.

• 한국수소및신에너지학회논문집
• /
• 제13권1호
• /
• pp.13-23
• /
• 2002

Hydrogenation properties of Mg-Ni and Mg-Ti-Ni alloys were investigated by Pressure-Composition Isotherm (PCI) test. Those alloys were fabricated by a new alloying method, Rotation-Cylinder Method (RCM). The as-cast microstructure of Mg-10 mass% Ni alloy consists of an island-like hydride forming $\alpha$-Mg phase and the eutectic structure. After 350 cyclic tests, Mg-lO mass % Ni alloy was pulverized into fine particles of 100 nm. The fine particles, which have a large specific surface area, are highly reactive with hydrogen. However, extreme pulvehzation can separate Mg from $Mg_2Ni$ in the eutectic structure, so $Mg_2Ni$ of the eutectic structure cannot behave as a dissociated hydrogen supplier.

• 한국물환경학회지
• /
• 제29권2호
• /
• pp.204-211
• /
• 2013

In this study, the deriving optimum conditions for decolorization of Acid Orange II solution was carried using $TiO_2$ advanced oxidation process. After that, on base of the deriving results, the range of dye concentration was estimated. In addition, acute toxicity test was also carried to assess toxicity unit according to decolorization and TOC removal. In case of the blockage of light, 20 mg/L of dye solution, and 0.5 g $TiO_2$, the effect of decolorization at pH 3 was larger than at pH 6 and 10, so it was shown that decolorization is dependent on pH. The use of 5 g $TiO_2$ showed best performance of decolorization, but that of 3 g $TiO_2$ was chosen to optimum condition in considering of economical aspects. Four light sources, sun, fluorescent lamp, BLB lamp, and UV-B lamp, were used and decolorization was 99.4% and 100% at 50 mg/L, 98.6% and 99.7% at 100 mg/L for sun and UV-B lamp, respectively. In spite of the optimum condition of decolorization at pH 3, the evaluation of acute toxicity test showed highly toxic. In conclusion, although the optimum treatment of dye solution is performed, water ecology can be polluted in discharging it into water system. Therefore, it is needed to study of water ecological system with dye water treatment, and it takes all the circumstances into consideration.

• Korean Chemical Engineering Research
• /
• 제59권3호
• /
• pp.399-409
• /
• 2021

백운석을 칼슘/마그네슘 화합물 소재로 활용하기 위해 마이크로웨이브 소성로(950 ℃, 60 min)을 이용하여 소성하여 고반응성 경소백운석(CaO·MgO)을 제조하였다. Hydration test(ASTM C 110) 기준에 따라 실험을 실시하였으며 수화 반응성 결과, 중 반응성(max 74.1 ℃, 5 min)으로 분석 되었다. 경소백운석의 수화 반응에 기초하여 경소백운석과 염(MgCl₂·6H₂O) (a) 1:1, (b) 1:1.5, (c) 1:2 wt%로 실험을 진행하였다. 염 첨가 비율이 증가 할수록 경소백운석의 MgO가 Mg(OH)₂로 증가되는 것을 X-선 회절 분석 결과 확인하였다. 분리 반응 후 칼슘은 CaCl₂ 용액 상태로 80 ℃, 24 시간 동안 교반시켜 흰색 결정체인 CaCl₂가 제조 되었다. XRD 분석 결과, CaCl₂·(H₂O)x(calcium chloride hydrate)로 경소백운석과 염 첨가 반응에 의한 CaO는 CaCl₂로 분리 되는 것을 확인하였다. 그리고 CaCl₂ 용액에 NaOH 첨가 반응으로 순도 99 wt%의 Ca(OH)₂ 합성하였으며, 합성된 Ca(OH)₂를 열처리 과정을 통하여 CaO를 제조하였다. 탄산칼슘을 제조하기 위해 CaCl₂ 용액에 Na₂CO₃ 첨가 반응으로 CaCO₃를 합성하였으며, 형상은 큐빅(cubic) 형태로 순도 99 wt%로 분석 되었다.

• 한국식품영양과학회지
• /
• 제33권1호
• /
• pp.201-206
• /
• 2004

쑥 분말의 첨가와 원료육 등급이 돼지고기 햄의 저장성에 미치는 영향을 검토하기 위하여, 규격돈(B등급) 및 경산모돈(E등급)에 쑥 분말을 첨가한 것과 첨가하지 않은 네 종류의 돼지고기 햄을 제조하였다. $L^{*}$ 값은 $B_{o}$ 및 $B_{+}$ 햄은 저장 후기가 높았으며, $E_{o}$ 햄은 저장 2주째 가장 높았고, $E_{+}$ 햄은 저장 중 변화가 없었다. 그러나 B등급육 햄의 $L^{*}$ 값이 E등급육 햄보다 높았으며, $a^{*}$ 값은 E등급육 햄이 높았다. 햄의 pH는 저장 중 감소하다가 저장 8주까지 증가하였다. 아질산 잔류량은 저장 2주까지 급격히 감소하였으며, 쑥 분말의 첨가는 아질산 잔류량의 감소에 영향을 미쳤다. VBN 함량은 저장초기 6.90∼7.90 mg%이던 것이 저장 중 증가하여 8주 째에는 14.07∼14.83 mg%를 나타내었다. TBARS는 저장 중 증가하였으며, 쑥 분말을 첨가한 것이 첨가하지 않은 것보다 저장 4주와 6주 째에 더 낮았다. 총균수는 모든 햄이 저장 중에 증가하였으며, 쑥 분말의 첨가는 총균수에 영향을 미치지 않았다.