• The Journal of the Petrological Society of Korea
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• v.6 no.1
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• pp.1-18
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• 1997

Andesitic pyroclastics and lava flows are deposited as a part of composite volcanoes by Cretaceous volcanic activity in Geojae Island, off the coast of Korea. The andesitic pyroclastics are composed of tuff breccia and lapilli tuff minor intercalated tuff. Lava flows are divided into dense and porphyritic andesite containing phenocrysts of plagioclase, pyroxene, and/or hornblende. The andesitic rocks represent charactersitcs of carc-alkaline BAR association with basalt, basaltic andesite, andesite, and dacite to rhyolite. Major element variations of the volcanic rocks show that $Al_2O_3$, total FeO, CaO, MgO and $TiO_2$ decrease with increasing $SiO_2$ but $K_2O$ and total alkalis increase, and represent differntiation trend of calc-alkaline rock series. In spider diagram, contents of Sr, K, Rb, Ba, and Th are relatively high, but contents of Nb, P, Ti and Cr are low. These petrochemcial characteristics are similar to those of rocks from island arc or continental margein related to plate subduction. Chondrite-normalized REE patterns of volcanic rocks are paralle to subparallel, with LREE enriched than HREE, and show gradual increase of negative Eu anomaly from basalt to dacite and rhyolite, suggesting comagmatic fractional crystallization with minor effects of assimilation and magma mixing. Andesitic rocks are assumed medium-K orogenic andesites that formed in the tectomagmatic environment of subduction zone under normal continental margin arc.

• Economic and Environmental Geology
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• v.31 no.2
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• pp.111-125
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• 1998

Dispersion, migration and enrichment of environmental toxic elements from the Samkwang Au-Ag mine area were investigated based upon major, minor and rare earth element geochemistry. The Samkwang mine area composed mainly of Precambrian granitic gneiss. The mine had been mined for gold and silver, but closed in 1996. According to the X-ray powder diffraction, mineral composition of stream sediments and soils were partly variable mineralogy, which are composed of quartz, orthoclase, plagioclase, amphibole, muscovite, biotite and chlorite, respectively. Major element variations of the host granitic gneiss, stream sediments and soils of mining and non-mining drainage, indicate that those compositions are decrese $Al_2O_3$, $Fe_2O_3$, MgO, $TiO_2$, $P_2O_5$ and LOI with increasing $SiO_2$ respectively. Average compositional ranges (ppm) of minor and/or environmental toxic elements within those samples are revealed as As=<2-4500, Cd=<1-24, Cu=6-117, Sb=1-29, Pb=17-1377 and Zn=32-938, which are extremely high concentrations of sediments from the mining drainage (As=2006, Cd=l1, Cu=71, Pb=587 and Zn=481 ppm, respectively) than concentrations of the other samples and host granitic gneiss. Major elements (average enrichment index=6.53) in all samples are mostly enriched, excepting $SiO_2$, $Na_2O$ and $K_2O$, normalized by composition of host granitic gneiss. Rare earth element (average enrichment index=2.34) are enriched with the sediments from the mining drainage. Minor and/or environmental toxic elements within all samples on the basis of host rock were strongly enriched of all elements (especially As, Br, Cu, Pb and Zn), excepting Ba, Cr, Rb and Sr. Average enrichment index of trace elements in all samples is 15.55 (sediments of mining drainage=37.33). Potentially toxic elements (As, Cd, Cr, Cu, Ni, Pb, and Zn) of the samples revealed that average enrichment index is 46.10 (sediments of mining drainage=80.20, sediments of nonmining drainage=5.35, sediments of confluent drainage=20.22, subsurface soils of mining drainage=7.97 and subsurface soils of non-mining drainage=4.15). Sediments and soils of highly concentrated toxic elements are contained some pyrite, arsenopyrite, sphalerite, galena and goethite.

• Journal of Mechanical Science and Technology
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• v.20 no.1
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• pp.1-12
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• 2006

This work reviews the effects of catalyst formulation and exhaust gas composition on soot oxidation in CDPF (Catalytic Diesel Particulate Filter). DOC's (Diesel Oxidation Catalysts) have been loaded with Pt catalyst (Pt/$Al_{2}O_3$) for reduction of HC and CO. Recent CDPF's are coated with the Pt catalyst as well as additives like Mo, V, Ce, Co, Fe, La, Au, or Zr for the promotion of soot oxidation. Alkali (K, Na, Cs, Li) doping of metal catalyst tends to increase the activity of the catalysts in soot combustion. Effects of coexistence components are very important in the catalytic reaction of the soot. The soot oxidation rate of a few catalysts are improved by water vapor and NOx in the ambient. There are only a few reports available on the mechanism of the PM (particulate matter) oxidation on the catalysts. The mechanism of PM oxidation in the catalytic systems that meet new emission regulations of diesel engines has yet to be investigated. Future research will focus on catalysts that can not only oxidize PM at low temperature, but also reduce NOx, continuously self-cleaning diesel particulate filters, and selective catalysts for NOx reduction.

• Corrosion Science and Technology
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• v.4 no.4
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• pp.121-129
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• 2005

Basic design concept of the future steel structure requires environmental compatibility and maintenance free capability to minimize economic burdens. Recent trends in alloy design for advanced weathering steel include addition of various alloying elements which can enhance formation of stable and protective rust layer even in polluted urban and/or high $Cl^{-}$ environment. The effects of Ca, Ni, W, and Mo addition on the corrosion property of Ca-modified weathering steel were evaluated through a series of electrochemical tests (pH measurement and electrochemical impedance spectroscopy: EIS) and structural analysis on rust layer formed on the steel surface. Ca-containing inclusions of Ca-Al-Mn-O-S compound are formed if the amount of Ca addition is over 25 ppm. Steels with higher Ca content results in higher pH value for condensed water film formed on the steel surface, however, addition of Ni, W, and Mo does not affect pH value of the thin water film. The steels containing a high amount of Ca, Ni, W and Mo showed a dense and compact rust layer with enhanced amount of ${\alpha}-FeOOH$. Addition of Ni, W and Mo in Ca-modified weathering steel shows anion-selectivity and contributes to lower the permeability of $Cl^{-}$ ions. Effect of each alloying element on the formation of protective rust layer will be discussed in detail with respect to corrosion resistance.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.309-312
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• 2010

본 연구에서는 유동층반응기를 이용하여 왕겨의 탄화반응을 수행하였다. 탄화반응은 내경 40mm, 높이 1.8m의 유동층을 사용하였으며, 분산판은 다공성 스테인레스스틸을 사용하였다. 탄화반응은 질소를 이용하여 수행하였다. 왕겨 주입입자 크기는 직경 2.0mm, 0.715mm, 0.359mm, 0.194mm를 각각 사용하였으며, 유동층의 온도는 $400^{\circ}C$, $500^{\circ}C$, $600^{\circ}C$, $700^{\circ}C$에서 탄화특성을 측정하였다. 또한 유동층의 매질로는 직경 1.0mm의 Co-Mo-Fe/$Al_2O_3$ 촉매를 사용하였으며, 탄화물은 유동층상부에 설치된 사이크론에 의하여 포집 분리 되었다. 탄화온도, 유속, 입자크기 등 조업변수에 따른 생성 탄소체의 물성을 규명하여 최적 조업조건을 제시하였다.

• Journal of Environmental Health Sciences
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• v.26 no.3
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• pp.92-97
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• 2000

The treatment of the washout from small scale incinerator was performed physically, chemically and biologically. The results are as follows. 1. SS, FS removal efficiency of washout wastewater from incinerator was 67.4%, 37.4%, while SS, FS of sewage wastewater was removed 63.2% 35.4% respectively. 2. The optimal conditions for chemical coagulation turned out to be pH 7.5, alum(Al2O3 10%) 30ml/ι and polyelectrolyte(A-601P 0.1%) 4ml/ι. SS 86%, FS 89.5%, BOD 42.5% and CODMn, 63.5% was removed and the removal efficiency of some metals are shown as Pb 93.5%, Zn 86.5% and Fe 80.6%. The concentration of the effluent was SS 9mg/ι, BOD 98.4mg/ι, and CODMn 138.4mg/ι. 3. The removal efficiency in treating washout wastewater of incinerator through HBC-briquet media was getting higher with increasing HRT, and mixed wastewater with 1:1, 1:2 ratio could be met up to the standard limit with higher HRT than 12hr. Under the condition of 1:2 mix ratio and HRT 24 hr, removal efficiency of SS, BOD, CODMn, T-N and T-P was 92.1%, 90%, 87%, 48.2% and 48%, respectively, and the concentration of treated wastewater was SS 2.9 mg/ι, BOD 10.3mg/ι, CODMn 14.1mg/ι, T-N 11.6 mg/ι and T-P 1.3 mg/ι, respectively.

• Journal of computational fluids engineering
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• v.6 no.1
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• pp.1-13
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• 2001

The natural convection heat transfer and solidification in a stratified pool are studied. The flow and heat transfer characteristics in a heat generating pool are compared between single-layered and double-layered pools. And local Nusselt number distributions on outer walls are obtained to consider thermal loads on a vessel wall. The cooling and solidification of Al₂O₃/Fe melt in a hemispherical vessel are simulated to study the mechanism of heat transfer and temperature distribution. A unstructured mesh is chosen for this study because of the non-orthogonality originated from the boundaries of double-layered pool. Interface between the layers is modeled to be fixed. With this assumption mass flux across the interface is neglected, but shear force and heat flux are considered by boundary conditions. The colocated cell-centered finite volume method is used with the Rhie-Chow interpolation to compute cell face velocity. To prevent non-physical solutions near walls in case body force is large the wall pressure is extrapolated by the way to include body force. The numerical solutions calculated by current method show that averaged downward heat flux of the double-layered pool increases compared to single-layered pool and maximum temperature occurs right below the interface of the layers.

• Journal of Electrical Engineering and Technology
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• v.10 no.6
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• pp.2364-2367
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• 2015

In this study, we fabricated an electrolyte-insulator-metal (EIM) device incorporating a high-k Al₂O₃ sensing membrane using a porous anodic aluminum oxide (AAO) through a two-step anodizing process for pH detection. The structural properties were observed by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction patterns (XRD). Electrochemical measurements taken consisted of capacitance-voltage (C-V), hysteresis voltage and drift rates. The average pore diameter and depth of the AAO membrane with a pore-widening time of 20 min were 123nm and 273.5nm, respectively. At a pore-widening time of 20 min, the EIM device using anodic aluminum oxide exhibited a high sensitivity (56mV/pH), hysteresis voltage (6.2mV) and drift rate (0.25mV/pH).

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.167-167
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• 2013

최근 발수 특성은 자동차 표면, 건축 구조물, 가전제품 및 모바일 기기 등 여러 분야에서 사용되고 점차 그 필요성이 대두되고 있다. 이러한 발수성의 표면은 연 잎이나 곤충의 날개, 도마뱀의 발바닥 등 자연계의 여러 곳에서 관찰 할 수 있다. 특히 연 잎의 표면에서 나타나는 초발수 특성이 마이크로와 나노 크기의 돌기 구조와 표피 왁스 성분에 기인한다는 것이 밝혀지면서 이를 응용한 다양한 연구가 진행되고 있다. 본 연구에서는 물리적인 표면처리로 마이크로와 나노 구조물을 형성하고 그 위에 표면에너지를 낮출 수 있는 물질을 증착하여, 발수 특성을 가지는 표면을 개발하였다. 알루미늄 표면에 마이크로 크기의 알루미나(Al2O3) 분말을 이용한 블라스트(blast) 공정으로 마이크로 구조를 형성하고, 선형 이온 소스(LIS)를 이용한 Ar 이온 빔 에칭으로 나노 구조를 형성하였다. FE-SEM 분석을 통해 수~수십 마이크로 구조 위에 나노 크기의 구조가 형성 된 것을 관찰하였다. 마이크로와 나노 구조가 형성된 알루미늄의 표면에너지를 낮추기 위해 trimethylsilane (TMS) 및 Ar을 이용한 플라즈마처리로 표면에 기능성 코팅막을 형성하였다. 그 결과 TMS처리 전에 비해 표면에너지가 99.75 mJ/m2에서 9.05 mJ/m2으로 급격히 낮아지고 접촉각이 $54^{\circ}$에서 $123^{\circ}$로 향상되었다.

• The Korean Journal of Quaternary Research
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• v.10 no.1
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• pp.27-52
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• 1996

금강 퇴적물의 지화학적 특성을 파악하기 위하여 상류에서 하류까지 21개의 표층 퇴적물을 채취하고 총금속(Al, Fe, Mn, Cr, Co, Ni, Cu, Zn, Pb) 입도별 금속 및 존재형태별 금속을 분석하였다. 또한 하천에서 연안역까지 미량금속의 공간적 변화를 보기 위해 부유물 을 일정 간격으로 채취하여 미량금속을 분석하였다. 퇴적물 중 미량 금속 함량을 평균 입도 와 밀접히 관계하여 변화하며 세립질실트 이하 부분에서 가장높은 함량을 보였고 이 높은 함량은 하천 부유물 중 금속 함량과 Mn을 제외하고 거의 유사한 수준이었다. Pb은 조립질 모래에서도 높은 함량을 보이는데 이는 조립질 모래에 많이 포함된 정장석에 의한 영향이 되고 세립질 실트에서의 높은 금속 함량은 세립한 중광물에 의한 영향이다. Mn과 Pb을 제 안한 금속들은 퇴적물 중 주로(70% 이상) 결정 격자와 관계하여 존재하는데 이는 퇴적물의 주구성 입도가 조립하여 금속이 풍부하고 세립한 중광 물에 의한 영향이 크기 때문이다. 하 천에서 염하구로 금속 함량이 급격히 감소하는데 이는 용존 $Mn^{+2}$이온이 $MnO_2$로 변화하는 산화반응과 하천구역에서의 퇴적 그리고 염하구에서 금속이 적어 진 입자(염하구 내에서 유기물 분해/용해로 만들어지거나 재부유 작요에 의한 조립질 물질) 와 하천 부유물과의 혼합작용에 의해 이루어진다.