• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
• /
• pp.161-164
• /
• 2004

In this study, to develop the composition ceramics for the Ultrasonic vibrator, $Pb(Mn_{1/3}Nb_{2/3})O_3Pb(Zr.Ti)O_3$ system ceramics were manufactured as a function of PCN substitution. Its dielectric and piezoelectric characteristics were investigated. With increasing the amount of PCN substitution, electromechanical coupling factor(kp) were increased until 3mol% PCN and that after decreased. mechanical quality factor(Qm) showed the maxinum value at 2mol% PCN. Eletromechanical coupling factor, mechanical quality factor and dielectric constant were showed optimum value at PCN 2mol% as 0.58, 1630 and 1407, respectively for ultrasonic vibrator applications.

• 한국염색가공학회지
• /
• 제8권6호
• /
• pp.27-32
• /
• 1996

This research is to investigate the reaction kinetics by air-lift bioreactor using calcium hydroxide, the neutralization agent and immobilization media, for removing ethylene glycol remained after chemical pretreatment. It was found that the optimum hydraulic retention time was obtained as 24.2hours at the optimum F/M ratio of 1.32kg-$TCOD_{Mn}$/day.kg-MLVSS, and then, infiuent $TCOD_{Mn}$ and MLVSS concentration were 3,290mg/l and 2,472mg/l, respectively. During the steady state, the kinetics constants such as maximum specific substrate removal rate, half saturation velocity coefficient, yield coefficient and endogenous respiration coefficient were estimated in the base of $TCOD_{Mn}$ as substrate concentration. And they were 1.47day$^{-1}$, 3.95mg/l, 0.391 and 0.092day$^{-1}$, respectively. And also, the oxgen use coefficients for cell synthesis, a', and energy of maintenance, b', were obtained as 0.4kg-O$_{2}$/kg-$TCOD_{Mn}$ and 0.056day$^{-1}$, at the steady state by the experimental result of oxygen uptake rate.

• 상하수도학회지
• /
• 제22권6호
• /
• pp.633-640
• /
• 2008

In this research, the $3.6m^3/day$ scale pilot plant consisting preozonation, coagulation, flocculation, and ceramic membrane processes was operated for long term period to evaluate the validity of ceramic membrane filtration process for treating lake water containing high concentration manganese. The higher concentration of dissolved manganese($Mn^{2+}$) was effectively oxidized to the bigger insoluble colloidal manganese ($MnO^2$) by 1~2 mg/L ozone. The colloidal manganese reacted with coagulant (poly aluminium chloride, PAC) and then formed the big floc. Ceramic membrane rejected effectively manganese floc during membrane filtration. Dissolved organic carbon(DOC) removal was dependent upon $Mn^{2+}$ concentration. While average $Mn^{2+}$ concentration was 0.43 and 0.85 mg/L in raw water, DOC removal rate in preozonation was 26.5 and 13.5%, respectively. The decrease rate of membrane permeability was faster without preozonation than with preozonation while membrane fouling decreased with NOM oxidation by ozone. In conclusion, raw water containing high concentration of manganese can be effectively treated in preozonation-coagulation-ceramic membrane filtration system.

• 자원환경지질
• /
• 제12권4호
• /
• pp.181-195
• /
• 1979

The Nambu orebodies of the Okbang tungsten mine are hosted in the Precambrian amphibolite and Weonnam formation. These orebodies can be classified into two types; The scheelite-bearing ore vein occurring in the amphibolite (the Nambu 1, 2 adits) and tungsten-bearing quartz vein along the contact between the amphibolite and the Weonnam formation (the Young-ho, -1, -2, -3 levels). The scheelite-bearing ore vein in the amphilbolite is discontinuous, narrow, and highly irregular in geometry, occurring only within the amphibolite with which of the vein is graduational. Based on these feature of the mode of occurrence, the origin of this ore type might be attributed to a potential segregation of tungsten ore fluid in situ from hornblenditic basic magma of the host rock. Tungsten-bearing quartz vein, however, is considered to have deposited along the N30-60E trending fractures as a later hypothermal vein after the hornblendite was emplaced. The principal ore mineral is scheelite with minor amount of wolframite, and the gangue minerals are quartz, and small amounts of fluorite, pyrrhotite, chalcopyrite and calcite. Fluid inclusion study of minerals from the Nambu orebody reveals that the fluids in fluorite of the scheelite-bearning ore vein attained a temperature range of $208{\sim}256^{\circ}C$ and those in quartz from the tungsten-bearing quartz vein a temperature range of $220{\sim}357^{\circ}C$. The real formation temperatures can be somewhat higher than filling temperatures, if pressure correction is made. Chemical analysis of 8 amphibolitc samples on major and some trace elements indicate that the amphibolite is igneous origin. On a Niggli diagram (al-alk)versus c, the analytical values are plotted on an igneous field, and on a Niggli diagram mg versus c they follow a karroo igneous trend line. According to the Ba, Cr, and Ni versus Niggli mg plots suggested by Leake (1964), Okbang amphibolite fall outside a pelitic field and compare favorably with his plots form ortho-amphibolites. Analitical values of $MoO_3$ of 8 samples of scheelite minerals from the Nambu orebody indicate that the tungsten-bearing quartz vein (type n) of Nambu orebody shows a range from 1. 69% to 4.38% which is higher than 0.94%~3.25% $MoO_3$ for the scheelite-bearing ore vein (type I). This fact indicates that the type II was deposited in a lower $fO_2/higher$ $fO_2$ environment and under lower temperature than the type I. Analysis of major components $WO_3$, MnO, and FeO of 6 samples of wolframite from the type II veins revealed that they contain 73.35~76.2% $WO_3$, 7.94~11.63% MnO, and 10.53~14.82% FeO. MnO/FeO ratios of wolframite shows the range of 0.85~1.17 which suggests a slightly higher temperature type of deposits than other major tungsten deposits in the country.

• 전기화학회지
• /
• 제19권2호
• /
• pp.50-56
• /
• 2016

본 연구에서는 습식분쇄, 분무건조 및 열처리 공정을 통해 알루미늄 및 마그네슘이 치환된 구형의 스피넬계 $Li_{1.10}Mn_{1.86}Al_{0.02}Mg_{0.02}O_4$ 양극재료를 합성하였다. 이때 공정변수로는 전구체를 만드는 분무건조공정에서 고형분(20~30 wt%)을, 열처리 공정에서는 산소분위기 유무를 변수로 하였다. 제조된 모든 양극재료는 상온에서 매우 우수한 전지특성을 보여주었으나, 출력특성에 있어서는 5C 방전곡선이 기준이 되는 0.1C 방전곡선 대비 서로 상이한 거동을 보임을 확인하였다. 이러한 고출력 거동의 차이는 첫째, 충방전 곡선상에서 3.3 V(vs. $Li/Li^+$) plateau 구간의 반응 용량 측정을 통해 양극재료의 산소결함 수준의 차이로 인한 것임을 확인하였다. 공기분위기에서 제조한 양극재료는 산소분위기에서 제조한 것에 비해 두 배 이상의 plateau 거동을 보이고 있으며, 이러한 현상으로부터 제조된 양극재료의 산소결함 정도와 방전초기 과전압 정도는 상관관계가 있음을 확인할 수 있었다. 둘째로는 임피던스 측정을 통해 산출된 확산계수로부터 고형분이 상대적으로 낮은 상태에서 제조된 양극재료가 그렇지 않은 양극재료에 비해 상대적으로 절반 이하 낮은 값을 가지고 있음을 알 수 있었다. 또한 입자 내부 형상 분석을 통한 내부 치밀도 및 임피던스 분석을 통한 확산속도의 차이를 확인함으로써, 방전 말단의 과전압 거동은 입자 내부의 리튬이온 확산속도와 관련이 있음을 확인하였다. 확산계수는 고형분이 상대적으로 낮은 20 wt% 상태에서 제조된 양극재료의 경우가 가장 낮으며, 이는 동일 양극재료의 내부 공극률이 가장 높은 결과와 부합하는 것이다.

• 한국전기전자재료학회논문지
• /
• 제30권1호
• /
• pp.17-22
• /
• 2017

Effects of pH value and deposition time on the electrical properties of (NMC) Ni-Mn-Cu-O and (NMCC) Ni-Mn-Cu-Co-O thin films were investigated. The NMC and NMCC films were prepared by spin spray method. The crystal structure and thickness of the annealed films were changed by the pH value and deposition time, respectively. A single phase of cubic spinel structure was confirmed for the annealed films deposited from solutions with pH 7.6. The resistivity of the annealed films was affected by the crystal structure and microstructure. The TCR (temperature coefficient of resistance) was dependent on the $Mn^{3+}/Mn^{4+}$. Typically, the resistivity of $70.5{\Omega}{\cdot}cm$ and TCR of -3.56%/K at room temperature were obtained for NMCC films deposited from solutions with pH 7.6 for 5 min, and annealed at $450^{\circ}C$ for 3 h.

• 한국세라믹학회지
• /
• 제34권7호
• /
• pp.703-712
• /
• 1997

The PTCR devices of BaTiO3 doped with Sb2O3, SiO2 were prepared by Liquid Addition Method(LPAM) where doping sources were used in the forms of Liquid. The amounts of doping in LPMA is smaller than that in solid state mixing method. Also the doping process in LPMA is very suitable for BaTiO3-based PTCR devices because it is easy to obtain homogeneous mixing and reproductivity. By optimizing the doping condition in BaTiO3 system, (0.09 mol% Sb2O3, 0.25 wt% SiO2 and 0.02 wt% MnO2) it was possible to fabricate BaTiO3-based PTCR devices whee the room-temperature resistivity and specific resistivity were 15{{{{ OMEGA }}cm and 2$\times$106 respectively.

• 대한화학회지
• /
• 제44권3호
• /
• pp.220-228
• /
• 2000

청송 달기약수(상탕,중탕,하탕)의 수질특성을 파악하기 위해 1999년 5월부터 2000년 2월까지 약 1년 동안 계절별로 총 28개 항목의 함유성분을 분석하여 다음과 같은 결론을 얻었다. 각 탕별 약수의 수질에 큰 차이가 있었다. 하탕약수는 Mg과 Na이 상대적으로 높았?만? 중탕약수는 Ca, K, Si, Fe, Mn, 전기전도도, 총염기도, DO, $Cl^-$, $SO_4^{2-}$등에서 상대적으로 높은 값을 보였다. 건강상 유해성분인 As, Cd, $Cr^{6+}$, Hg는 검출되지 않았으며, Pb는 기준이하로 나타났다. 먹는물 수질기준을 초과한 항목으로는 경도, Fe와 Mn이었다. 그러나 샘물의 경우에는 이 기준을 적용하지 아니한다고 규정하였다. 약수의 계절별 특징으로는 온도를 제외한 기타 항목에서는 뚜렷한 차이가 없었다. 음용수에서 섭취할 수 있는 미네랄 양을 알아보고자 미국 국립과학아카데미의 하루 요구허용량과 섭취 음용수의 양을 1.O L로 하고 購종善嗤?기준으로 계산한 결과, Ca 35.05%, Mg 36.43%, Na 5.88∼10.63%, K 0.19∼0.57%, Mn 21.86∼43.72%, Zn 0.65%, Cr,Cu, P 등은 0.01% 이하이고, Fe는 95.1%이었다. 따라서 달기약수는 철분이 풍부한 약수임을 알 수 있었다.달기약수는 K index가 111.7∼254.6,O index가 2.3∼4.5로서 Hashimoto가 주장한 K index 5.2,O index 2.O을 상회하므로 건강에 좋고 맛있는 물의 조건을 만족하고 있다.

• 한국표면공학회지
• /
• 제52권6호
• /
• pp.350-356
• /
• 2019

In this study, the effect of mechanical polishing of carbon steel on the tribological properties of manganese phosphate coating on carbon steel has investigated. The microstructure, surface morphology and chemical composition were analyzed by SEM, EDS, and XRD. The surface roughness test was carried out in order to calculate Rvk value by 3D laser microscopy. Also, the tribology property of manganese phosphate coating was tested by ball-on disk. In the results of EDS analysis, coating layer consists of elements such in Mn, P, Fe, and O. XRD showed that (Mn,Fe)₅H₂(PO₄)₄·4H₂O in manganese phosphate coating layer was formed by the chemical reaction between manganese phosphate and elements in carbon steel. As the mechanical polishing degree increased, the friction coefficient was reduced. The rougher the mechanical polishing degree, the better corrosion resistance was obtained.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
• /
• pp.364-367
• /
• 2003

[ $(Ba_{0.93}Ca_{0.07})_{1.009}(Ti_{0.82}Zr_{0.18})O_{2.}$ ] 이고 첨가제로 $MnO_2$ 0.2wt%, $Y_2O_3$ 0.18wt%, $SiO_2$ 0.15wt% 유리프릿으로 $(Ba_{0.4}Ca_{0.6})SiO_3$ 1 wt%를 첨가한 조성을 이용하여 각 공정별 최적화를 통해 고 신뢰성이면서 고용량 MLCC를 제작하였다 고 신뢰성 MLCC 제작에서 있어 최적의 소성온도를 확인 할 수 있었으며 외부 전극을 통한 도금액 침투를 방지하여 절연저항 특성을 향상할 수 있음을 확인하였다. 또한 1608 크기의 1.13uF의 용량을 가지는 고 신뢰성 MLCC를 제작하였다.