• 한국환경농학회지
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• 제27권4호
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• pp.328-336
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• 2008

폐금속 광산에서 유출되는 광산배수로 인한 수계의 수질오염 영향을 파악하기 위하여 삼보광산 광미댐 침출수 및 하류 하천수의 화학성분 및 미량금속을 분석 검토한 결과는 다음과 같다. 삼보광산 주변 광미댐 침출수의 pH 값은 $5.8{\sim}6.9$ 사이로 중성에 가까운 약산성이였다. 주 광미댐 침출수의 주요 용존 화학성분 평균치는 EC 1.77 dS/m, $SO_4^{2-}$ 929, $K^+$ 14.6, $Ca^{2+}$ 263.3, $Mg^{2+}$ 46.9 mg/L 이였다. 특히 화학성분 중 EC 값과 $SO_4^{2-}$ 농도는 벼의 농업용수 피해한계 농도 (EC 1.0 dS/m, $SO_4^{2-}$ 54.0 mg/L)를 상회하였다. 광산 침출수의 Cd 평균 농도($0.016{\sim}0.021\;mg/L$)는 농업용수 수질기준인 0.01 mg/L을 초과하였고, Cd 최고치는 수질기준의 4배정도 높았다. 또한 미량금속 중 Zn, Fe 및 Mn 농도는 FAO의 관개용수 최대 권고치(Cd 0.01, Zn 2.0, Fe 5.0, Mn 0.2 mg/L)를 초과하였고, 특히 Zn 및 Mn 평균 농도는 권고치의 $8{\sim}26$배, $45{\sim}313$배 이상 높았다. 본 조사결과에서 광산배수에 의한 수계의 수질오염은 하류 1 km 이상까지 영향을 미치는 것으로 나타났다. 광산배수와 하천수의 수질항목 중 pH 값은 용존 Cd, Zn, Al 및 Mn 농도와 부의 상관을, 주 오염성분인 EC 값, $SO_4^{2-}$ 및 $Ca^{2+}$ 농도는 각각의 Cd, Zn, Al 및 Mn 농도와 고도의 정의 상관을 보였다. 또한 주요 화학성분 중에서는 pH 값이 EC 값 및 $SO_4^{2-}$ 농도와 부의 상관을 보였다.

• 한국지구과학회지
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• 제32권7호
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• pp.707-718
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• 2011

보성-화순지역 하상퇴적물에 대한 지질집단별 자연배경치와 지구화학적 특성에 대해 연구하였다. 이를 위해 1차 수계를 따라 하상퇴적물시료 186개를 채취하였고, 실험실에서 자연건조 시킨 후, XRF, ICP-AES, NAA분석을 실시하였다. 하상퇴적물의 지질집단별 자연배경치와 지구화학적 특성을 알기 위해, 시료를 화강암질편마암(GGn)지역과 반상변정질편마암(PGn)지역으로 분리하였다. 화강암질편마암지역의 주성분원소 함량은 $SiO_2$ 45.5-73.09 wt.%, $Al_2O_3$ 12-20.76 wt.%, $Fe_2O_3$(T) 3.72-8.85 wt.%, $K_2O$ 2.38-4.2 wt.%, MgO 0.75-2.77 wt.%, $Na_2O$ 0.78-1.88 wt.%, CaO 0.27-2.1 wt.%, $TiO_2$ 0.56-1.72 wt.%, $P_2O_5$ 0.06-0.73 wt.% and MnO 0.03-0.95 wt.%이고 반상변정질편마암지역의 주성분원소 함량은 $SiO_2$ 43.74-70.71 wt.%, $Al_2O_3$ 11.54-25.05 wt.%, $Fe_2O_3$(T) 3.44-13.46 wt.%, $K_2O$ 2.08-3.86 wt.%, MgO 0.65-2.99 wt.%, $Na_2O$ 0.63-1.7 wt.%, CaO 0.35-2.07 wt.%, $TiO_2$ 0.68-4.17wt.%, $P_2O_5$ 0.1-0.31 wt.% and MnO 0.07-0.33 wt.%이다. 화강암질편마암지역 하상퇴적물의 위해원소 함량은 크롬 41.7-242 ppm, 코발트 7.6-25.1 ppm, 니켈 12-61 ppm, 구리 10-47 ppm, 아연 48.5-412 ppm, 납 17-215 ppm이고 반상변정질편마암지역은 크롬 29.6-454 ppm, 코발트 5.9-53.7 ppm, 니켈 8.7-287 ppm, 구리 6.4-134 ppm, 아연 43.6-370 ppm, 납 15-37 ppm이다. 화강암질편마암지역에서 크롬은 MgO와 코발트는 $Al_2O_3$, $Fe_2O_3$(T), MgO와 니켈은 $Fe_2O_3$(T), CaO, MgO와 높은 상관성을 가지나, 구리, 아연, 납은 비교적 낮은 상관성을 보였다. 반상변정질편마암지역에서 일반적으로 크롬, 코발트, 니켈, 구리는 주성분원소와 대부분 높은 상관성을 보였으나, 아연과 납은 낮은 상관성을 보였다.

• 에너지공학
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• 제8권2호
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• pp.256-264
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• 1999

본 연구에서는 메탄의 부분산화반응에 미치는 base metal 의 영향을 살펴보기 위하여 6~l2wt%의 Mn, Cu, V, Co, Cr 그리고 Ba 등이 2 wt% Pt, 70 wt% Alumina, 28 wt% Ceria and Zirconia 와 함께 cordierite (2MgO.2Al$_2$O$_3$.5SiO$_2$)에 담지된 Pt-B/cordierite 촉매(B: base metal)를 사용하여 메탄의 부분산화반응 실험을 수행하였다. 메탄의 부분산화반응에 대한 활성은 Ba, Co그리고 Cr 담지 촉매는 Ni담지 촉매와 유사하게 Mn, Cu, V을 담지 했을 때 보다 우수한 것으로 나타났으나, 코크 생성에 대한 활성도 큰 것으로 나타났다. 또한 5wt% Ni/Al$_2$O$_3$촉매를 이용한 메탄의 부분산화반응 실험 후의 촉매에 대한 XRD 분석결과 Ni은 3가지 형태의 상으로 존재하는 것을 확인할 수 있었으며, 촉매층 전단에서는 주로 NiAl$_2$O$_4$와 NiO 형태로 존재하여 메탄의 산화반응이 일어나며, 그리고 촉매층 후단에서는 환원상태의 Ni로 존재는 것으로 보아 개질반응이 일어나는 것을 알 수 있었다.

• 열처리공학회지
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• 제37권3호
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• pp.121-127
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• 2024

We investigate the effect of T6 heat treatment on the microstructure and mechanical properties of AA365 (Al-10.3Si-0.37Mg-0.6Mn-0.11Fe, wt.%) alloy fabricated by vacuum-assisted high pressure die casting by means of thermodynamic calculation, X-ray diffraction, scanning and transmission electron microscopy, and tensile tests. The as-cast alloy consists of primary Al (with dendrite arm spacing of 10~15 ㎛), needle-like eutectic Si, and blocky α-AlFeMnSi phases. The solution treatment at 490 ℃ induces the spheroidization of eutectic Si and increase in the fraction of eutectic Si and α-AlFeMnSi phases. While as-cast alloy does not contain nano-sized precipitates, the T6-treated alloy contains fine β' and β' precipitates less than 20 nm that formed during aging at 190℃. T6 heat treatment improves the yield strength from 165 to 186 MPa due to the strengthening effect of β' and β' precipitates. However, the β' and β' precipitates reduce the strain hardening rate and accelerate the necking phenomenon, degrading the tensile strength (from 290 to 244 MPa) and fracture elongation (from 6.6 to 5.0%). Fractography reveals that the coarse α-AlFeMnSi and eutectic Si phases act as crack sites in both the as-cast and T6 treated alloys.

• 환경위생공학
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• 제14권3호
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• pp.99-106
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• 1999

This research was carried out to investigate chemical pretreatment using lime and limestone in treating abandoned mine drainage with anaerobic treatment. If treating lime with abandoned mine drainage, after 2day, pH was increased to 5.6, and $SO_4^{2-}$, Fe, Al, Pb and Mn were removed 5.7%, 63%, 57, 45% and 28%, respectively. It was estimated that lime dosage was 2,000mg/L for increasing to pH 7. If treating limestone with abandoned mine drainage, after 2day, pH was increased to 3.67, and $SO_4^{2-}$, Fe, Al, Pb and Mn were removed 4.7%, 26%, 22% 18% and 8%, respectively. It could be showed that limestone did slowly react with temperature increasing. If treating anaerobic limestone packing column with abandoned mine drainage, for experimental period, average pH was 4.51, and average $SO_4^{2-}$, Fe, Al, Pb and Mn were removed 4.5%, 15.3%, 20.1%, 23.7% and 5.87%, respectively. So, it would not be suitable for abandoned mine drainage. But if utilizing limestone as pretreatment process for treating abandoned mine drainage with SRB, because it did initally neutralize abandoned mine drainage, it could forward to stabilize system.

• 천문학회보
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• 제36권2호
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• pp.147.1-147.1
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• 2011

We investigate the chemical differentiation in F, G, K type stars with and without planets to extend the work by Kang et al. (2011) to various spectral types. Since the primordial chemical composition has been preserved in the stellar atmosphere, stellar metallicity can provide the information on the primordial material, which is the potential building block of planets. Therefore, we can explore the favored conditions for planet formation through the comparison of chemical compositions between planet-host stars (PHSs) and stars without planets. In this work, we analyze 19 F, G, and K type stars. In each spectrum, we measure equivalent widths (EWs) of Fe, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Co, and Ni using TAME (Tools for Automatic Measurement of Equivalent width). The abundances of these species can be derived with the measured EWs and MOOG code (Sneden 1973). Like results by precedent studies, we find that planet-host stars have abundances higher than stars without planets. The typical difference in the abundances of Na, Mn, Co and Ni is $0.4{\pm}0.2dex$. In addition, as found in Kang et al. (2011), Mn is the most different element between PHSs and comparison stars.

• 한국세라믹학회지
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• 제31권9호
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• pp.975-980
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• 1994

The thermal properties of cordierite (2MgO.2Al2O3.5SiO2)+30 wt% clay+ Xwt% MnO2 of infrared radiator have been investigated as a function of MnO2 additives (X=0,0.1,0.25,0.5,1.0,1.5,2.0,2.5). The thermal expansion coefficient was decreased with increasing amounts of MnO2 additives. Otherwise, the spectral emissivity was increased in the below 4.5 ${\mu}{\textrm}{m}$ wavelength. Also, the infrared radiator of cordierite system which spectral emissivity was approximately 1.0 can be attainable at from 4.5 ${\mu}{\textrm}{m}$ to 8 ${\mu}{\textrm}{m}$ wavelength. The spectral emissivity was decreased from 8 ${\mu}{\textrm}{m}$ to 14 ${\mu}{\textrm}{m}$ above X=2.5.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1317-1319
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• 1994

The thermal properties of Cordierite$(2MgO.2Al_2O_3.5SiO_2)$ + 30 [wt%]clay + X[wt%]MnO_2$ of infrared radiator have been investigated as a function of $MnO_2$ additives (X=0, 0.1, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5). The thermal expansion coefficient was decreased and the spectral emissivity was increased only in the below $4.5{\mu}m$ wavelength with increasing amaunts(wt%) of $MnO_2$ additives. Also, the infrared radiator of Cordierite system which spectral emissivity was approximately 1.0 can be attainable at from $4.5{\mu}m$ to $8{\mu}m$ wavelength. The spectral emissivity was decreased from $8{\mu}m$ to $14{\mu}m$ at X=2.5.

• 대한전기학회논문지
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• 제44권6호
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• pp.799-805
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• 1995

An infrared radiator of cordierite system were manufactured byslurry casting anddry pressing method. The characteristics of cordierite (2MgO.2Al$_{2}$O$_{3}$.5SiO$_{2}$)+30wt% clay+Xwt% MnO$_{2}$ of infrared radiator have been investigated as a function of MnO$_{2}$ additives (X=0, 0.1, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5). The thermal expansioncoefficient was decreased with increasing amounts of MnO$_{2}$ additives. Otherwise, the spectral emissivity was increased in the below 4.5.mu.m wavelength. Also, the infrared radiator of cordierite system which spectral emissivity was approximately 1.0 can be attainable at from 4.5.mu.m to 8.mu.m wavelength. The spectral emissivity was decreased from 8.mu.m to 14.mu.m above X=2.5.

• Journal of Welding and Joining
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• 제22권3호
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• pp.56-61
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• 2004

Friction stir weldability of AZ31B Mg alloy was studied using microstructural observation and mechanical tests. Defect free joints was obtained under the condition of 2000rpm-100mm/min. In TMAZ, a lot of twin deformation were observed due to the mechanical effect of the FSW tool and thus relatively high hardness was obtained. In SZ, the twin deformation was disappeared by recovery and the hardness decreased because the. grain structure was coarsened by dynamic recrystallization and grain growth. The Al-Mn precipitates were observed throughout the joint regions. On the other hand, $$\beta$-Mg_{17}Al_{12}$ intermetallic compounds were not observed in either of the zone. The joint efficiency was about 80% and the impact value of the joint was almost equal to that of base metal.