• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.2 no.2
• /
• pp.20-32
• /
• 1992

$Na_2O-CaO-MgO-Al_2O_3-SiO_2$ glass was taken as a basic glass and then $Li_2O$ O.5wt%, $K_2O$ 2.0wt% were substituted to $Na_2O$content, MgO 12.0wt %, ZnO 6.0wt % to CaO content. And also nucleation agent $ZrO_2 and $CaF_2$ were added to 1-2wt% respectively. The crystal according to the compositions appeared wollastonite, diopside and diopside.tremolite. The glasses substituted NazO by LizO was decreased thermal expansion coeffcient but substituted by ZnO was opposite direction and both of them increased bending strength. In the ratio of ZrOz to CaF, each 1: 1 and 1: 2 have shown considerable crystal growth at $1000^{circ}C~1050^{\circ}C$ and high bending strength, but the glass in the ratio 1: 2 have shown lowest thermal expansion coefficient. The activation energy was at the glass in the ratio of ZrO, to CaFz 1:2 evaluated 55.24kvsl/mol by Ozawa type and 53.05kal/mol by kissinger type.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.165.1-165.1
• /
• 2016

Zn의 수요는 매년 증가하지만 매장량의 한계로 대체용 물질계가 개발이 필요한 시점이다. Zn보다 상대적으로 풍부하고 동일 두께의 Zn 코팅층과 비교하여 우수한 내식성을 보이는 Al과 Mg의 코팅층을 제작하여 Al-Mg 코팅 강판의 특성 분석 및 평가를 실시하였다. Al-Mg 코팅층은 99.99%의 Al, 99.9%의 Mg target을 사용하여 스퍼터링을 이용하여 냉연강판 위에 코팅하였다. 증발물질과 기판과의 거리는 7cm 이며, 기판은 세척을 실시한 후 클리닝 챔버에 장착하고 ~10-5 Torr 까지 진공배기를 실시하였다. 클리닝 챔버가 기본 압력까지 배기되면 아르곤 가스를 주입하고 기판 홀더에 -800 V의 직류 전압을 인가하여 약 30분간 글로우 방전 청정을 실시하였다. 기판의 청정이 끝나면 아르곤 가스를 차단하고 코팅 챔버로 시편을 이송 후 코팅층 성분의 구성형태에 따라 Al과 Mg을 코팅하였다. Al-Mg 코팅층은 $3{\mu}m$의 두께를 기준으로 Mg wt.%의 비율을 5% ~ 90%까지 변화시키며 코팅하였다. 그리고 후속 공정으로 질소 분위기 $400^{\circ}C$에서 10분간 열처리를 하였다. Al-Mg 코팅층을 주사전자현미경으로 관찰한 결과, 표면에서는 Al-Mg 코팅층에 존재하는 Mg 함량이 높아질수록 grain의 크기가 증가하였고 단면에서는 열처리 전의 치밀한 구조에서 열처리 후에는 주상구조 혹은 grain 구조가 선명해지는 것을 볼 수 있었으며 글로우방전분광기로 Al과 Mg의 성분 비율변화를 확인할 수 있었다. 또한 Al-Mg가 코팅된 강판을 염수분무시험을 통해서 내부식 특성을 확인하였다. Al-Mg 코팅 강판의 염수분무시험 결과, Mg 함량이 낮은 Al-Mg 코팅층은 열처리 후 뚜렷한 내식성 향상을 보였으며 Mg 조성 변화에 따라 일정한 경향성을 보였다. 하지만 Mg 함량이 높은 Al-Mg 코팅층은 열처리 후 급격한 내식성 저하와 함께 시편간의 편자가 커지는 것을 확인 할 수 있었다. 최적의 내식성을 보이는 Mg의 조성을 확인하기 위해서는 향후 보다 변별력이 높은 평가가 결과가 필요하다고 판단되어진다.

• Journal of Nutrition and Health
• /
• v.26 no.1
• /
• pp.89-97
• /
• 1993

This study was carried out to estimate the relationship between dietary intake, blood level, and urinary excretion of minerals and blood pressure in 30 healthy adults living in rural area of Korea(12 males and 18 females). Analysis for the nutritional status of the subjects were performed by 3-day dietary intake record, duplicated diet collection, 24-hour urine collection, and venous blood sampling before measuring blood pressure. The mean blood pressure of subjects was 117.50/80.83mmHg in males and 110.00/73.89mmHg in females. The mean daily intakes of Na, K, Ca, P, Mg, Fe, Cu, Zn estimated for 3 days were 199.97mEq, 49.56mEq, 452.50mg, 725.57mg, 240.40mg, 12.48mg, 3.41mg, 8.28mg, respectively. The serum concentration of Na, K, Ca, P, Mg, Fe, Cu, Zn were 139.83mEq/dl, 4.06mEq/dl, 8.86mg/dl, 3.28mg/dl, 2.13mg/dl, 0.12mg/dl, 0.12mg/dl, 0.14mg/dl, respectively. The 24-hour urinary excretions of Na, K, Ca, p, Mg, Fe, Cu, Zn estimated for 169.60mEq, 39.37mEq, 80.40mg, 398.97mg, 64.77mg, 0.21mg, 0.07mg, 0.29mg, respectively. No significant correlation was found between dietary intake, serum concentration, and urinary excretion of minerals and blood pressure. But, the serum Ca/Mg ratio showed negative correlation with the systolic and diastolic blood pressure at the level of significance of 5%. The study verifies the need for more systematic studies on interrelationship among minerals and mineral requirements in normotensive and hypertensive subjects.

• Clean Technology
• /
• v.28 no.1
• /
• pp.1-8
• /
• 2022

To confirm the applicability of the water gas shift reaction for the production of high purity hydrogen for petroleum cokes, an unutilized low grade resource, Cu/ZnO/MgO/Al₂O₃ (CZMA), catalyst was prepared using the co-precipitation method. The prepared catalyst was analyzed using BET and H₂-TPR. Catalyst reactivity tests were compared and analyzed in two cases: a single LTS reaction from syngas containing a high concentration of CO, and an LTS reaction immediately after the syngas passed through a HTS reaction without condensation of steam. Reaction characteristics in accordance with steam/CO ratio, flow rate, and temperature were confirmed under both conditions. When the converted low concentration of CO and steam were immediately injected into the LTS, the CO conversion was rather low in most conditions despite the presence of large amounts of steam. In addition, because the influence of the steam/CO ratio, temperature, and flow rate was significant, additional analysis was required to determine the optimal operating conditions. Meanwhile, carbon deposition or activity degradation of the catalyst did not appear under high CO concentration, and high CO conversion was exhibited in most cases. In conclusion, it was confirmed that when the Cu/ZnO/MgO/Al₂O₃ catalyst and the appropriate operating conditions were applied to the syngas composition containing a high concentration of CO, the high concentration of CO could be converted in sufficient amounts into CO₂ by applying a single LTS reaction.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2015.11a
• /
• pp.163-163
• /
• 2015

아연(Zn)을 대체할 수 있는 물질계 인 알루미늄(Al)과 마그네슘(Mg)을 본 연구에서는 In-Line PVD 장치의 스퍼터링 소스를 이용하여 냉연강판 위에 코팅하고 열처리를 실시하여 전자현미경 및 글로우방전 분광기를 이용한 코팅층의 특성 분석 및 염수분무시험을 통해 내식성을 평가하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2014.11a
• /
• pp.22-22
• /
• 2014

아연(Zn)을 대체할 수 있는 물질계 인 알루미늄(Al)과 마그네슘(Mg)을 본 연구에서는 전자빔 증착을 이용하여 냉연 강판 위에 다층으로 코팅하고 열처리를 실시하여 전자현미경 및 글로우방전 분광기를 이용한 코팅층의 특성 분석 및 염수 분무시험을 통해 내식성을 평가하였다.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.29 no.1
• /
• pp.99-105
• /
• 2000

The purpose of this study was to evaluat the Zn, Cu, Mn and Ni status and correlation of their concentrations in serum, urine, hair and fingernail in female college students. As the results are follows; The mean age of subjects was 22.5 years and height, weight and BMI were 160.1 cm, 51.0 kg and 20.0 respectively. The daily intake of energy 1769.5 kcal and the ratio of carbohydrate, fat and protein for energy is 60 : 20 : 15. The daily intake of energy (88.5%), vitamin B2 (86.1%), Ca (75.4%), Fe (58.3%) and Zn (63.0%) of subjects did not reach to Korean Recommended Dietary Allowance (RDA). The daily mean intake of Zn, Cu, Mn and Ni were 7.56 mg, 2.30 mg, 3.81 mg and 0.18 mg respectively. The concentrations of Zn in serum, urine, hair and nail were 85.6$\mu\textrm{g}$/dL, 391.2$\mu\textrm{g}$/day, 174.6$\mu\textrm{g}$/g and 102.4$\mu\textrm{g}$/g respectively and those Cu were 84.2$\mu\textrm{g}$/dL, 56.6 $\mu\textrm{g}$/day, 20.3$\mu\textrm{g}$/g and 4.3$\mu\textrm{g}$/g respectively. The concentrations of Mn in serum, urine, hari and nail were 0.2$\mu\textrm{g}$/dL, 1.1$\mu\textrm{g}$/day, 1.8$\mu\textrm{g}$/g and 1.6$\mu\textrm{g}$/g respectively and those of Ni were 0.6$\mu\textrm{g}$/dL, 24.5$\mu\textrm{g}$/day, 3.5$\mu\textrm{g}$/g and 3.1$\mu\textrm{g}$/g respectively. The daily intake of Mn showed the positive correlations with concentration of Mn in hair (p<0.05) and the daily intake of Ni was positively correlated with urinary exretion (p<0.05) and hair contents (p<0.001) of Ni. The more detailed studies about these trace mineral status should be required.

• Transactions on Electrical and Electronic Materials
• /
• v.4 no.6
• /
• pp.13-16
• /
• 2003

Mn-doped $ZnGa_{2}O_{4}$:$Mn^{2+}$ (M=S, Se) thin film phosphors have been grown using a pulsed laser deposition technique under various growth conditions. The structural characterization carr~ed out on a series of $ZnGa_{2}O_{4}$:$Mn^{2+}$ (M=S, Se) films grown on MgO(l00) substrates usmg Zn-rich ceramic targets. Oxygen pressure was varied from 50 to 200 mTorr and Zn/Ga ratio was the function of oxygen pressure. XRD patterns showed that the lattice constants of the $ZnGa_{2}O_{4}$:$Mn^{2+}$ (M=S, Se) thin film decrease with the substitution of sulfur and selenium for the oxygen in the $ZnGa_2O_4$. Measurements of photoluminescence (PL) properties of $ZnGa_{2}O_{4}$:$Mn^{2+}$ (M=S, Se) thin films have indicated that MgO(100) is one of the most promised substrates for the growth of high quality $ZnGa_2O_{4-x}M_{x}$:$Mn^{2+}$ (M=S, Se) thin films. In particular, the incorporation of Sulfur or Selenium into $ZnGa_2O_4$ lattice could induce a remarkable increase in the intensity of PL. The increasing of green emission intensity was observed with $ZnGa_2O_{3.925}Se_{0.075}:$Mn^{2+}$ and $ZnGa_2O_{3.925}S_{0.05}$:$Mn^{2+}$ films, whose brightness was increased by a factor of 3.1 and 1.4 in comparison with that of $ZnGa_{2}O_{4}$:$Mn^{2+}$ films, respectively. These phosphors may promise for application to the flat panel displays.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.2
• /
• pp.313-321
• /
• 2000

This research is to remove heavy metals from AMD(Acid Mine Drainage) using AFMR(Anaerobic Floating Media Reactor) process. Two AFMR were operated at HRT(hydraulic retention time) of 3 days. COD/sulfate ratio from 0.3 to 0.8, temperature from $30^{\circ}C$ to $35^{\circ}C$, and alkalinity of 1.000mg/l(as $CaCO_3$). At COD/sulfate($SO{_4}^{2-}$) ratio of 0.5 and temperature of $35^{\circ}C$, the ratio of reduced sulfate($SO{_4}^{2-}$)/removed COD(mg/mg) kept about 1 and the reactor achieved 99.99% of Cr, Pb anee Fe, 98% of Cd, and 90% of Mn removal efficiencies, respectively. Decreasing temperature to $30^{\circ}C$ increased the ratio of reduced sulfate($SO{_4}^{2-}$)/removed COD(mg/mg) to 1.37. Amount of sulfate reduction maximized at the temperature of $30^{\circ}C$ and the COD/sulfate ratio of 0.4 in the influent and then removal efficiencies of heavy metals were 99.99% of Fe, 99.99% of Pb, 99,99% of Cr, 97.3% of Mn, 99.9% of Zn, 99.9% of Cd and 99.9% of Cu.

• Clean Technology
• /
• v.23 no.4
• /
• pp.429-434
• /
• 2017

To investigate the effect of magnesium oxide addition, $Cu/ZnO/MgO/Al_2O_3$ (CZMA) catalysts were prepared using co-precipitation method with fixed molar ratio of Cu/Zn/Mg/Al as 45/45/5/5 mol% for low-temperature water gas shift reaction. Synthesized catalysts were characterized by using BET, $N_2O$ chemisorption, XRD, $H_2-TPR$ and $NH_3-TPD$ analysis. The catalytic activity tests were carried out at a GHSV of $28,000h^{-1}$ and a temperature range of $200{\sim}320^{\circ}C$. At the same condition, magnesium oxide added catalyst (CZMA 400) showed that the lowest reduction temperature and stable presence of $Cu^+$, that is active species and abundant weak acid site. Also magnesium oxide added catalysts (CZMA) showed higher catalytic activity at temperature range above $240^{\circ}C$ than the catalyst without magnesium oxide (CZA). Consequently, CZMA 400 catalyst is considered to be excellent catalyst showing CO conversion of 77.59% without deactivation for about 75 hours at $240^{\circ}C$, GHSV $28,000h^{-1}$.