• 공업화학
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• 제3권1호
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• pp.53-63
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• 1992

프로필렌을 선택산화시켜 아크로레인을 제조하는 반응을 Bi-molybdate 촉매상에서 고정층 반응기를 사용하여 연구하였다. ${\alpha}-Bi_2Mo_3O_{12}$위에 $MoO_3$를 담지시킨 M/BM-series 촉매는 함침법으로 제조되었고, 역으로 BM/M-series 촉매는 $MoO_3$위에 ${\alpha}-Bi_2Mo_3O_{12}$을 침전시켜 제조하였다. 또한 촉매의 특성분석을 위하여 질소흡착과 XRD, SEM을 이용하였다. M/BM-series 촉매에서는 $MoO_3$가 작은 입자로 분산되고 ${\alpha}-Bi_2Mo_3O_{12}$의 결정구조는 $MoO_3$상이 추가되어도 그 형상이 변하지 않는 채로 유지되었으나, BM/M-series 촉매의 표면형상 및 전체 구조는 촉매제조 중에 생기는 침전물인 $Bi(OH)_3$가 소성 도중 $MoO_3$와 반응하여 ${\alpha}-Bi_2Mo_3O_{12}$을 형성하는 관계로 그 조성에 따라 매우 불규칙적으로 변화하였다. 반응실험 결과, 두 종류의 촉매 모두에서 excess $MoO_3$가 포함되었을 때 활성이 크게 증가하였는데, 이는 선별산화반응이 주로 ${\alpha}-Bi_2Mo_3O_{12}$에서 일어나고 $MoO_3$는 ${\alpha}-Bi_2Mo_3O_{12}$에 산소 공급을 원활히 하여 활성을 증가시키기 때문으로 판명되었다. 또한 이러한 활성 증가는 ${\alpha}-Bi_2Mo_3O_{12}$와 기계적 혼합물 (mechanical mixture)에서도 관찰되었다.

• 한국전기전자재료학회논문지
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• 제21권2호
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• pp.111-117
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• 2008

We have studied surface roughness, contamination of impurity, bonding with some gas element, reflectance and zeta potential on masks to be generated or changed during photolithography/dry or wet etching process. Mask surface roughness was not changed after photolithography/dry etching process. But surface roughness was changed on some area under MoSi film of Cr/MoSi/Qz. There was not detected any impurity on mask surface after plasma dry etching process. Reflectance of mask was increased after variable plasma etching treatment, especially when mask was treated with plasma including $O_2$ gas. Blank mask was positively charged when the mask was treated with Cr plasma etching gas($Cl_2:250$ sccm/He:20 $sccm/O_2:29$ seem, source power:100 W/bias power:20 W, 300 sec). But this positive charge was changed to negative charge when the mask was treated with $CF_4$ gas for MoSi plasma etching, resulting better wet cleaning. There was appeared with negative charge on MoSi/Qz mask treated with Cr plasma etching process condition, and this mask was measured with more negative after SC-1 wet cleaning process, resulting better wet cleaning. This mask was charged with positive after treatment with $O_2$ plasma again, resulting bad wet cleaning condition.

• 한국재료학회지
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• 제26권4호
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• pp.200-206
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• 2016

This study was carried out to investigate the effect of W substitution on the precipitation behavior of ${\chi}$ and ${\sigma}$ phases in super duplex stainless steel. The ${\chi}$ phase was precipitated at the interface of ferrite / austenite phases and inside the ferrite phase at the initial stage of aging. With an increase in the aging time, the volume fraction of the ${\chi}$ phase increased, and then decreased with the transformation from the ${\chi}$ phase to the ${\sigma}$ phase. The ${\sigma}$ phase was precipitated later than the ${\chi}$ phase, and the volume fraction of x phase increased with the increase in the aging time. The ferrite phase was decomposed into the new austenite (${\gamma}2$) and ${\sigma}$ phases by aging treatment. The decomposition of the ferrite phase into the ${\gamma}2$ and ${\sigma}$ phases was retarded by W substitution for Mo. The volume fraction of the ${\chi}$ phase increased and that of the ${\sigma}$ phase decreased due to W substitution. The ${\chi}$ and ${\sigma}$ phases were intermetallic compounds, which had lower nickel concentration, and higher chromium, molybdenum, and tungsten concentrations. The ${\chi}$ phase has higher molybdenum and tungsten concentrations than those of the ${\sigma}$ phase. The amounts of chromium and nickel in the ${\chi}$ and ${\sigma}$ phases did not change, but these phases have higher concentrations of molybdenum and tungsten due to W substitution for Mo.

• KSBB Journal
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• 제20권5호
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• pp.350-354
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• 2005

수소생산을 최적화하기 위하여 Enterobacter cloacae YJ-1을 이용해 생산성에 미치는 탄소원 농도, 질소원 농도, 금속이온 농도, 아미노산 효과로서 회분식 배양을 통하여 실험을 수행하였다. 각종 탄소원의 종류에 따라 수소생산을 검토한 결과 glucose 첨가시에 가장 양호하였다. 따라서 glucose 농도를 변화시켜 수소생산량을 조사한 결과 $2\%$(w/v) 농도에서 최대를 보여 975.4 mL/L를 생산하였다. 각종 질소원 중에서 가장 효과적인 질소원은 yeast extract이었으며, 최대 수소생산량은 $1.5\%$(w/v) 농도에서 1651.5mL/L이었다. 금속이온으로는 $Na_2MoO_4$가 가장 효과적으로 나타나 $0.04\%$(w/v) 농도에서 1753.3 mL/L를 생산하였다. 아미노산은 cystein에서 가장 생산량이 많았으며, 다음은 proline, histidine, alanine 등 순이었다. 회분식 배양의 최적 조건하에 수소를 연속적으로 생산하기 위하여 반연속배양을 행한 결과 $3\%$ (w/v) 농도에서 2215.4 mL/L로 가장 높았다. 생산균주의 대사에 관한 물질을 보다 세밀히 조사하고 연속적인 수소생산을 살펴 산업적인 공정개발도 가능하리라 생각된다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2001년도 학술대회논문집
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• pp.93-99
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• 2001

광원별로 형광등 32W 3등을 사용한 터널과 고압나트륨 램프 100W를 사용한 터널, 그리고 저압나트륨 램프 36W와 91W를 혼용한 터널의 조도 및 휘도를 측정한 결과 조도 및 휘도의 균제도는 3 가지 광원이 모두 거의 일치하였으나, 평균 조도와 정균 휘도값에 있어서 저압나트륨 램프를 사용한 터널이 절반 수준이 되는 차이를 보였다. 또한 경제성 평가 도구인 WEELS를 이용하여 터널의 길이를 300[m], 터널 폭을 10.7[m]로 일정하게 하여 경제성을 평가한 결과, 연간 비용에 있어서 고압나트륨 100W가 비용이 가장 켰고, 그 다음이 형광등 32W 3등용, 그 다음이 저압나트륨(36W+91W)이었지만 그 값은 근소한 차이였다.

• 자원환경지질
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• 제31권5호
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• pp.375-388
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• 1998

The purpose of this study is to investigate the ore genesis and occurrence of the Wondong polymetallic mineral deposits. The Pb-Zn, Fe and W-Mo mineralizations are found in skarn zones which formed mainly in or along the fault shear zones with the $N25-40^{\circ}W$ and $N10-50^{\circ}E$ directions, whereas the Cu-Mo mineralization is appeared hydrothermal replacement zone. The skarn minerals consist mainly of garnet and epidote, which were the last alteration phases between pneumatolytic and hydrothermal stages. The mineral paragenesis toward the late stage are as follows: arsenopyrite, scheelite, magnetite, pyrite, pyrrhotite, sphalerite, galena, chalcopyrite and molybdenite. Average ore grades are 0.33 g/t Au, 46.29 g/t Ag, 0.06% Cu, 4.4% Pb, 2.61% Zn and 29.39% Fe in tunnels, and 0.31 % Cu, 0.52% Pb, 6.29% Zn, 29.29% Fe, 0.03% Mo and 0.12% $WO_3$ in drill cores. Fluid inclusion data shows that Type I (liquid-rich), Type II (vapor-rich) and Type III (halite-bearing) inclusions are coexisted and their homogenization temperatures are quite similar. This indicates that boiling conditions have been reached during the mineralization. It is also likely that the ore solutions were evolved through the mixing between magmatic and meteoric waters. Rhyolite and quartz porphyry far the mineralization probably are not responsible of the Wondong polymetallic mineral deposits.

• Nuclear Engineering and Technology
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• 제7권2호
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• pp.107-118
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• 1975

천이금속을 구성하고 있는 성분 이온을 변형가능한 이온으로 취급함으로써 크로미움, 몰리브데늄 및 텅스텐의 격자진동을 전자각 모텔에 외해 수식화했다. 이 모델은 전하에 대한 두 변수와 다섯 개의 힘상수를 모두 합쳐 7개의 모텔상수를 포함하고 있으며 이들의 수치는 금속의 탄성 계수에 관한 자료와 중성자 산란 실험에 의해 측정된 격자진동의 특성 주파수 값과 일치하도록 하여 결정했다. 한편 전자각 모델은 Cr, Mo 및 W등 세 금속의 성파 확산곡선, 주파수 분포함수 및 비열을 계산하는데 응용하였고 그 결과를 실험치와 비교하였다. 이로부터 전자각 모델로도 천이금속의 격자진동에 대한 특성을 만족스럽게 설명할 수 있다는 것을 알아내었다. 또한 다른 격자 모델과의 비교를 통하여 전자각 모델의 유용성을 검토했다.

• 한국표면공학회지
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• 제51권6호
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• pp.354-359
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• 2018

NaCl-induced hot corrosion behavior of ASTM T22 (Fe-2.25Cr-1Mo), T91 (Fe-9Cr-1Mo), T92 (Fe-9Cr-1.8W-0.5Mo), 347HFG (Fe-18-Cr-11Ni), and 310H (Fe-25Cr-19Ni) steels was studied after spraying NaCl on the surface. During corrosion at $600-800^{\circ}C$ for 50-100 h, thick, non-adherent, fragile, somewhat porous oxide scales formed. All the alloys corroded fast with large weight gains owing to fast scaling and destruction of protective oxide scales. Corrosion rates increased progressively as the corrosion temperature and time increased. Corrosion resistance increased in the order of T22, T91, T92, 347HFG, and 310H, suggesting that the alloying elements of Cr, Ni, and W beneficially improved the corrosion resistance of steels. Basically, Fe oxidized to $Fe_2O_3$, and Cr oxidized to $Cr_2O_3$, some of which further reacted with FeO to form $FeCr_2O_4$ or with NiO to form $NiCr_2O_4$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.826-829
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• 2002

$MoO_3$ thin films were deposited on electrode and heater screen-printed alumina substrates in en atmosphere by RF reactive sputtering. The deposition was performed at $300^{\circ}C$ with 350W of a forward power in an $Ar-O_2$ atmosphere. The working pressure was maintained at $3{\times}10^{-2}$mtorr and all deposited films were annealed at $500^{\circ}C$ for 5hours. The surface morphology of films was observed by using a SEM and crystalline phases were analyzed by XRD. The sensing properties were investigated in term of gas concentration under exposure of reducing gases such as $H_2$, $NH_3$ and CO.

• 대한화학회지
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• 제13권1호
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• pp.37-40
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• 1969

The separation and species of $MoO_4^{--}$ and $WO_4^{--}$ at the various PH value have been studied by the method of cation exchange chromatography. Elution curves of $MoO_4^{--}$ and $WO_4^{--}$ have been made with a 5 cm column of the resin, $Dowe{\times}50W{\times}12$(100-200 mesh), using solutions of various PH value as eluent. Complete separation of $MoO_4^{--}$ and $WO_4^{--}$ was obtained in each PH of 10% EtOH. According to the evaluation of peak position and number of peaks of elution curves, it is likely to exist cationic species of $MoO_4^{--}$.