• 한국광물학회지
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• 제13권3호
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• pp.147-163
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• 2000

The mineralogy and chemical composition of reddish to brownish yellow residual soils, so called "Hwangto" have been examined according to representative host rocks. The result of the study indicates that Hwangto consists of 40-80% clay minerals and various minerals such as quartz, feldspar, hornblende, goethite, and gibbsite. Clay minerals include kaolinite, halloysite, illite, hydroxy interlayered vermiculite (HIV), mica/vermiculite interstratifield mineral and chlorite. The mineralogical constituents and contents of Hwangto were different depending on the types of host rocks. Moreover, the Jurassic granitic rocks contain relatively more kaolin minerals, whereas the Cretaceous granitic rocks contain more HIV and illite. In addition, reddish Hwangto contains relatively more kaolinite and HIV, and yellowish Hwangto contains more illite and halloysite. It is suggested that feldspars and micas of host rocks were chemically weathered into illite, halloysite, illite/vermiculite interstratified minerals, and HIV, and finally into kaolinite. Compared with their host rocks, the major chemical compositions of Hwangto tend to contain more $Al_2O_3,\;Fe_2O_3,\;H_2O$ in amount and less Ca, Mg, and Na. Hwangto contains relatively high amount of trace elements, P, S, Zr, Sr, Ba, Rb, and Ce including considerable amount of Li, V, Cr, Zn, Co, Ni, Cu, Y, Nb, La, Nd, Pb, Th in excess of 10 ppm. Relatively high amount of most trace elements were detected in the Hwangto. The major and minor chemical compositions of the Hwangto were different depending on the types of host rocks. However, their difference was in the similar range compared with the compositions of host rocks.

• 한국환경농학회지
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• 제13권3호
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• pp.321-337
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• 1994

주택용 소형 퇴비화용기에 의한 부엌쓰레기의 퇴비화 가능성을 검토하기 위하여 두가지 용기(Type 1과 Type 2)를 제작하여 실험실 실험을 통하여 조사하였다. 두 용기의 구조는 같으나 차이점은 Type 1은 보온을 하였고 Type 2는 보온을 하지 않았다. 겨울철 실험을 통하여 Type 2는 우리나라의 기후 여건에 사용이 불가능한 것으로 판단되어 봄철 및 여름철 실험에서 제외하였다. 따라서 Type 1에 대한 계절 실험결과를 요약하면 다음과 같다. 1) 퇴비화기간 중 상승한 최고온도는 봄철 $58^{\circ}C$, 여름철 $57^{\circ}C$, 겨울철 $41^{\circ}C$였다. 따라서 우리나라의 기후조건에서는 반드시 보온이 필요하다는 것이 확인되었다. 2) 퇴비화원료물질의 무게는 8주 후 평균 62.5% 그리고 부피는 평균 74% 감소하였다. 3) 퇴비충의 밀도는 봄철 0.7kg/l, 여름철 0.8kg/l, 겨울철 1.1kg/l였다. 4) 수분함량은 전 퇴비화기간동안 큰 변동이 없었으며 8주 후 봄철 75.6%, 여름철 76.6%, 겨울철 76.6%였다. 5) pH는 계절에 따라 큰 차이를 보였으며 여름철에 가장 높았고, 겨울철에 가장 낮았다. 8주 후 봄철 6.13, 여름철 8.62, 겨울철 4.75였다. 6) 퇴비화시간의 경과에 따른 회분 및 유기물 함량은 유기물 분해속도가 빠를수록 증감현상이 뚜렷하였고 cellulose 및 lignin은 증가, hemicellulose 함량은 감소하였다. 7) 질소함량은 3.1-5.6%로 높았으며, 특히 여름철에 가장 높았다. 암모늄태 질소는 전반기에 증가했다가 감소하는 경향이었으며 겨울철 2주째 3,243mg/kg, 봄철 3주째 6,052mg/kg, 여름철 6주째 30,828mg/kg으로 가장 높았다. C/N율은 퇴비화시간이 경과함에 따라 감소하였으나 차이는 크지 않았다. 그러나 질산화는 봄 및 여름철에만 일어나고 겨울철에는 거의 일어나지 않았다. 8) 휘발성 및 고급유기산함량은 초기에 증가했다가 계절적으로 시기적 차이는 있으나 감소하였다. 총 유기산의 최고농도는 겨울철 2주째 10.1%, 봄철 2주째 5.8%, 여름철 4주째 15.7%였다. 9) 퇴비의 부숙도와 무관하게 각 무기성분함량은 $P_2O_5$ 0.9-4.4%, $K_2O$ 1.6-2.9%, CaO 2.4-4.6%, MgO 0.30-0.80%였다. 10) CN 및 각종 중금속함량도 퇴비화시간에 따라 큰 변화가 없었으며 각 함량범위는 계절 구분없이 CN 0.11-28.89mg/kg, Zn 24-l30mg/kg, Cu 5-219mg/kg, Cd 0.8-14.3mg/kg, Pb 7-42mg/kg, Cr ND-30mg/kg, Hg $ND-132.16\;{\mu}g/kg$이었다.

• 한국전기전자재료학회논문지
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• 제11권10호
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• pp.842-848
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• 1998

The stability of paraseodymium-based zinc oxide varistor consisting of Zn-Pr-Co-Cr-Y oxide was investigated according to yttria additives under different stress conditons, such as 0.8V\ulcorner\ulcorner/373K/12h and 0.85V\ulcorner\ulcorner/393K/12h. Wholly, all varistor after the stress showed nearly symmetric and stable I-V characteristics. Particularly, in the case of 2.0mol% and 4.0mol% yttria-added varistor showing a good I-V characteristics, the varation rate of varistor voltage were less 1% and that of nonlinear coefficient were about degree of 5%, and what is remarkable, leakage current with increasing stress time during the applied stress was almost constant. It the light of these facts, it is estimated that varistor constituents having 2.0mol% and 4.0mol% yittria, respectively, will be utilized to various application fields.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.339-339
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• 2002

In the RABiTS approach to coated conductor development, successful (both economic and technological) depends on the refinement and optimization of each of three important components: the metal tape substrate, the buffer layer(s), and the HTS layer. Here we will report on the ORNL approach and progress in each of these areas. - Most applications will require metal tapes with low magnetic hysteresis, mechanical strength, and excellent crystalline texture. Some of these requirements are competing. We report on progress in obtaining a good combination of these characteristics on metal alloys of Ni-Cr and Ni-W. - The deposition of appropriate buffer layers is a crucial step. Recently, base research has shown that the presence of a stable sulfur superstructure present on the metal surface is needed for the nucleation and epitaxial growth of vapor-deposited seed buffer layers such as YSZ, CeO$_2$ and SrTiO$_3$. We report on the details and control of this superstructure for nickel tapes, as well as recent results for Cu and Ni-13%Cr. - Processes for deposition of the HTS coating must economically provide large values of the figure-of-merit for conductors, current x length. At ORNL, we have devoted efforts to a precursor/post-annealing approach to YBCO coatings, for which the deposition and reaction steps are separate. We describe motivation for and progress toward developing this approach. - Finally, we address some issues for the implementation of coated conductors in real applications, including the need for texture control and electrical stabilization of the HTS coating.

• Environmental Engineering Research
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• 제19권1호
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• pp.15-22
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• 2014

In this study, the performances of various adsorbents-red mud, zeolite, limestone, and oyster shell-were investigated for the adsorption of multi-metal ions ($Cr^{3+}$, $Ni^{2+}$, $Cu^{2+}$, $Zn^{2+}$, $As^{3+}$, $Cd^{2+}$, and $Pb^{2+}$) from aqueous solutions. The result of scanning electron microscopy analyses indicated that the some metal ions were adsorbed onto the surface of the media. Moreover, Fourier transform infrared spectroscopy analysis showed that the Si(Al)-O bond (red mud and zeolite) and C-O bond (limestone and oyster shell) might be involved in heavy metal adsorption. The changes in the pH of the aqueous solutions upon applying adsorbents were investigated and the adsorption kinetics of the metal ions on different adsorbents were simulated by pseudo-first-order and pseudo-second-order models. The sorption process was relatively fast and equilibrium was reached after about 60 min of contact (except for $As^{3+}$). From the maximum capacity of the adsorption kinetic model, the removal of $Pb^{2+}$ and $Cu^{2+}$ were higher than for the other metal ions. Meanwhile, the reaction rate constants ($k_{1,2}$) indicated the slowest sorption in $As^{3+}$. The adsorption mechanisms of heavy metal ions were not only surface adsorption and ion exchange, but also surface precipitation. Based on the metal ions' adsorption efficiencies, red mud was found to be the most efficient of all the tested adsorbents. In addition, impurities in seawater did not lead to a significant decrease in the adsorption performance. It is concluded that red mud is a more economic high-performance alternative than the other tested adsorption materials for applying a removal of multi-metal in seawater.

• 대한화학회지
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• 제58권2호
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• pp.169-178
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• 2014

A new series of metal complexes of V(IV), Pd(II), Pt(IV), Ce(IV) and U(VI) with 3-[(3-chlorophenyl)-hydrazono]-pentane-2,4-dione (Cphpd) were synthesized and characterized by elemental analysis, molar conductivity, magnetic moment measurements, UV-vis, FT-IR and $^1H$ NMR as well as TG-DTG techniques. The data indicated that the Cphpd acts as a bidentate ligand through the hydrazono nitrogen and one keto oxygen. The kinetic parameters have been evaluated by using Coats Redfern (CR) and Horowitz-Metzeger (HM) methods. The thermodynamic data reflected the thermal stability for all complexes. The calculated bond length and the bond stretching force constant, F(U=O), values for $UO_2$ bond are $0.775{\AA}$ and $286.95Nm^{-1}$. The bond lengths, bond angles, dipole moment and the lowest energy model structure of the complexes have been determined with DFT calculations. The antimicrobial activity of the synthesized ligand and its complexes were screened.

• 광물과 암석
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• 제33권4호
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• pp.307-324
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• 2020

백두산 북동쪽으로 약 25 km 떨어져있는 지역의 마이오세 현무암(황송푸 현무암, 20 Ma)에 대한 주성분원소와 미량원소, Sr-Nd 동위원소 조성에 대한 연구가 수행되었다. 황송푸 현무암은 비현정질 암석으로 Na2O+K2O=3.5~4.7 wt.%, MgO=9.9~11.1 wt.%을 보인다. Mg 성분이 풍부한 감람석(Mg#=75~86)과 단사휘석(Mg#=72~85), Ca성분이 풍부한 사장석 미반정을 함유하고 있다. 이 현무암은 경희토류원소 부화가 나타나는 해양도현무암과 유사한 미량원소 패턴을 보이고, 높은 Cr(394~479 ppm)과 Ni(389~519 ppm) 성분, Nb-Ta 부화 이상치, Rb과 Ba을 포함하는 LILE가 부화되어 있는 특징을 보인다. 이러한 조직과 주성분원소/미량원소조성 데이터는 황송푸 현무암이 알칼리 마그마 계열에 속하는 원시적인 마그마임을 나타낸다. 황송푸 마그마는 상승하는 도중에 분별결정작용, 지각오염, 마그마혼합과 같은 분화작용을 거의 경험하지 않은 액상선 환경에서 고화된 암석으로 이는 황송푸 현무암이 부분용융이 일어났던 맨틀에서의 특성을 지니고 있음을 반영한다. 황송푸 현무암의 높은 (Gd/Yb)sample/(Gd/Yb)PM 비율(2.8~3.5)은 황송푸 현무암이 판내부 환경에서 형성된 마그마로써 석류석이 존재하는 맨틀에서 페리도타이트의 낮은 부분용융(3~5%)으로 형성되었다. BSE보다 모두 높은 143Nd/144Nd와 87Sr/86Sr 성분을 보이는 황송푸 현무암은 이 지역 아래 부화된 맨틀영역이 존재한다는 것을 의미한다. 황송포 현무암은 과거(ancient)의 태평양판 섭입대에 의해 공급되어 재활용된 해양지각 혹은 대륙지각으로 교대작용을 경험한 맨틀에서 부분용융에 의해 형성되었다.

• 한국산학기술학회논문지
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• 제13권1호
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• pp.462-469
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• 2012

크롬(VI)-4,4'-bipyridine 착물(4,4'-bipyridinium dichromate)를 합성하여, 적외선분광광도법(IR), 유도결합 플라즈마(ICP) 등으로 구조를 확인하였다. 여러 가지 용매하에서 4,4'-bipyridinium dichromate를 이용하여 벤질 알코올의 산화반응을 측정한 결과 유전상수(${\varepsilon}$) 값이 큰 용매 순서인 시클로헥센<클로로포름<아세톤$CH_3$, H, m-Br, m-$NO_2$)를 효과적으로 산화시켰다. 그리고 전자받개 그룹들은 반응속도가 감소한 반면에 전자주개 치환체들은 반응속도를 증가시켰다. 또한 Hammett 반응상수(${\rho}$) 값은 -0.63(303K) 이었다. 그러므로 본 실험에서 알코올의 산화반응 과정은 먼저 크토메이트 에스테르 형성과정을 거친 후, 속도결정단계에서 양성자 전이가 일어나는 메카니즘임을 알 수 있었다.

• Korean Chemical Engineering Research
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• 제48권2호
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• pp.172-177
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• 2010

본 논문에서는 SOFC 금속연결재로서 Crofer22APU를 적용하고자 표면에 전도성 산화막($La_{0.8}Sr_{0.2}CoO_3$)을 습식코팅 후, SOFC 작동환경에서 산화거동, 전기적 특성변화 및 미세구조 변화를 관찰하였다. 코팅 전 샌드블러스트 장치를 이용한 Crofer22APU 표면처리를 통하여 코팅막/금속의 접합특성을 개선시킬 수 있었으며, 320 mesh의 입자크기를 갖는 알루미나 분말을 이용하여 표면처리한 경우 접착특성이 극대화되었다.$La_{0.8}Sr_{0.2}CoO_3$ 코팅된 시편의 전기적 특성 평가는 4-wire 법을 이용하여 SOFC 작동환경에서 약 4,000 시간 장기성능 평가하였으며 $12mW{\cdot}cm^2$의 낮은 면저항값을 얻을 수 있었다. 실험종료 후 미세구조 분석결과에서도 전도성 산화막($La_{0.8}Sr_{0.2}CoO_3$) 코팅이 금속의 부식으로 인한 산화층의 생성속도를 늦추고 이로 인한 금속의 전기적 특성이 감소하는 것을 방지하는데 유효함을 확인하였다.

• Corrosion Science and Technology
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• 제11권1호
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• pp.9-14
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• 2012

The formation of the Fe-Al inhibition layer in hot-dip galvanizing is a confusing issue for a long time. This study presents a characterization result on the inhibition layer formed on C-Mn-Cr and C-Mn-Si dual-phase steels after a short time galvanizing. The samples were annealed at $800^{\circ}C$ for 60 s in $N_{2}$-10% $H_{2}$ atmosphere with a dew point of $-30^{\circ}C$, and were then galvanized in a bath containing 0.2 %Al. X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) was employed for characterization. The TEM electron diffraction shows that only $Fe_{2}Al_{5}$ intermetallic phase was formed. No orientation relationship between the $Fe_{2}Al_{5}$ phase and the steel substrate could be identified. Two peaks of Al 2p photoelectrons, one from metallic aluminum and the other from $Al^{3+}$ ions, were detected in the inhibition layer, indicating that the layer is in fact a mixture of $Fe_{2}Al_{5}$ and $Al_{2}O_{3}$. TEM/EDS analysis verifies the existence of $Al_{2}O_{3}$ in the boundaries of $Fe_{2}Al_{5}$ grains. The nucleation of $Fe_{2}Al_{5}$ and the reduction of the surface oxide probably proceeded concurrently on galvanizing, and the residual oxides prohibited the heteroepitaxial growth of $Fe_{2}Al_{5}$.