• 한국산학기술학회논문지
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• 제19권10호
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• pp.598-602
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• 2018

석유정제공장에서 사용된 폐촉매의 특성을 조사하여 바나듐 레독스 흐름전지용 소재인 전해액의 제조에 대하여 연구하였다. 석유정제공정에서 사용된 폐촉매의 총공극 부피, 비표면적 및 평균 기공크기는 BET법과 BJH법으로 계산하여 각각 3.96cc/g, 13.81m2/g, 1.15A 구하여 폐촉매에서 바나듐을 회수하여 전해액으로 제조 할 수 있음을 확인하였다. 폐촉매를 TG-DTA분석결과, $25^{\circ}C$부터 $700^{\circ}C$ 범위에서 중량손실이 약 23wt%였다. 폐촉매의 성분을 ICP 장비를 분석하여 황, 바나듐, 니켈, 알루미늄, 망간 철 구리 등의 원소를 확인하였다. 또한 TEM 장비로 측정한 결과 바나듐 외 다른 원소들이 결정성 클러스터가 밝은 점으로 명백하게 드러남을 알 수 있었다. 액액 추출법을 사용하여 폐촉매로 부터 바나듐을 99.25%로 분리하여 추출한 바나듐용액의 전기화학적 특성분석을 위해 CV(cyclic votammetry)측정한 결과, 산화/환원피크가 나타남으로서 전해질 용액으로서의 가능성을 보여주고 있다. 또한 폐촉매로 부터 추출된 바나듐 용액의 순도를 더욱 높여 전해질 용액을 제조하면 기존 상용화된 전해질 성능과 같은 것을 제조 할 것으로 사료된다.

• 한국분말재료학회지
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• 제16권3호
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• pp.196-202
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• 2009

A visible-light photoactive $TiO_{2-x}N_x$ photocatalyst was synthesized successfully by means of cogrinding of anatase-$TiO_2(a-TiO_2)$ in $NH_3$ ambient, followed by heat-treatment at $200^{\circ}C$ in air environment. In general, it is well known that the grinding-operation induces phase transformation of a-$TiO_2$ to rutile $TiO_2$. This study investigates the influence of the amount of $NH_3$ gas on the phase transformation rate of a-$TiO_2$ and enhancement of visible-light photocatalytic activity, and also examines the relation between the photocatalytic activity and the period of grinding time. The phase transformation rate of a-$TiO_2$ to rutile is retarded with the amount of NH3 injected. And the visible-light photocatalytic activity of samples, was more closely related to the period of grinding time than $NH_3$ amount injected, which means that the doping amount of nitrogen into $TiO_2$ more effective to mechanical energy than $NH_3$ amount injected. XRD, XPS, FT-IR, UV-vis, Specific surface area (SSA), NOx decomposition techniques are employed to verify above results more clearly.

• Korean Chemical Engineering Research
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• 제48권3호
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• pp.292-299
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• 2010

그래핀(graphene)은 $sp^2$ 탄소원자들이 벌집 격자를 이룬 형태의 2차원 나노시트를 의미하며, 높은 비표면적(이론치 $2600m^2\;g^{-1}$)과 우수한 전기전도도(전형치 $8{\times}10^5S\;cm^{-1}$) 및 기계적 강도로 인해 리튬이온전지의 음전극 활물질 및 초고용량 커패시터의 전극 활물질로서 사용 가능성이 높아지고 있다. 본 총설에서는 현재까지 알려진 그래핀 나노시트와 그래핀을 기반으로 하는 나노복합체의 제조법을 소개하고, 이를 리튬이온전지와 초고용량 커패시터의 전극소재로 적용하였을 때의 특성을 그 나노구조적 관점과 연관하여 논의하였다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.241.1-241.1
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• 2011

Numerous possible applications for $ZrO_2$ nanotubes exist such as for catalyst support structures, for sensing or for applications as a solid state electrolyte. Especially, because of a large specific surface area, high efficiency for solid oxide fuel cell (SOFC) application at low temperature can be expected for nanotublar structures in even small size. A zirconium precursor, Tetrakis (ethylmethylamino) zirconium, TEMAZr and $H_2O$ oxidant were used to deposit$ZrO_2$ thin films on an anodized aluminum oxide (AAO) templates having sub-100nm cylindrical pores by atomic layer deposition (ALD) in the temperature range of 150~250$^{\circ}C$. The crystalline structures of as-prepared and post-annealed $ZrO_2$ nanotubes were characterized by x-ray diffraction and high-resolution transmission electron microscopy. The as-prepared samples at $150^{\circ}C$ and $200^{\circ}C$ were showed amorphous, whereas a mixed phase of tetragonal, monoclinic and amorphous polymorph was observed at $250^{\circ}C$. In the bulk, zirconia remains monoclinic phase up to $1,175^{\circ}C$, however, $ZrO_2$ nanotubes were showed tetragonal phase upon post thermal treatments merely at $400^{\circ}C$. This trend may be indicative of high-curvature surfaces of nanotubes and thereby the presence of intrinsic compressive strain. The amount of amorphous structures in the mixed phase as well as as-grown $ZrO_2$ nanotubes were also gradually decreased by subsequent heat treatment.

• 임산에너지
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• 제25권2호
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• pp.55-63
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• 2006

전통 방식으로 제조되어 시중에 유통 중인 2종의 참나무 백탄과 2종의 소나무 백탄에 대한 물성과 수용액 상 구리(II) 이온 흡착 성질을 시험하였다. 물성시험 결과, 탄의 pH는 약 9.5-9.8로 시료 탄간의 차가 크지 않았다. 원소 조성에 있어서는, 4종 시료 탄의 탄소(C) 함량이 약 85-90%로 나타났으며 S사 소나무탄의 수소(H) 함량이 1.62%로 타 시료에 비해 3배가량 높았다. 4종 시료 탄의 요오드 흡착량과 비표면적 측정의 결과에서는, 소나무탄이 참나무탄 보다 높게 나타났다. 이들 시료 목탄의 수용액 내 구리(II) 이온 흡착율 측정 시험에서는, 목탄 시료의 처리양이 늘어날수록, 처리 시간이 길수록, 그리고 pH가 높을수록 높은 구리(II) 이온 흡착율을 나타냈다.

• 한국패류학회지
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• 제21권1호
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• pp.47-56
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• 2005

A series of radiotracer experiments were employed to quantitatively compare the biokinetics of uptake from the dissolved phase (influx rates), uptake from the various types of food source (assimilation efficiency), and loss (efflux) of Ag between Potamocorbula amurensis and Macoma balthica. Simultaneously, influx rates of dissolved Cd in both clams were determined to compare with those of Ag. Effects of salinity on influx rates were evaluated in these 2 euryhaline species, as were effects of clam size. Influx rate of Ag and Cd (${\mu}g g^{-1}$ [dry wt.] $d^{-1}$) increased linearly with metal concentrations. Influx rates of Ag in both clams were 3 to 4 times those of Cd. Absolute influx rates of the 2 metals were 4 to 5 times greater in P. amurensis than M. balthica, probably because of differences in biological attributes (i.e. clearance rate or gill surface area). As salinity was reduced from 20 to 2.5 psu, the influx rate of Cd in P. amurensis increased 4-fold and that of Ag increased 6-fold, consistent with expected changes in speciation. Weight-specific metal influx rates (${\mu}g g^{-1}$ [dry wt.] $d^{-1}$) were negatively correlated with the tissue dry weight of the clams, but most rate constants determining physiological turnover of assimilated metals were not affected by clam size.

• 한국환경과학회지
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• 제21권12호
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• pp.1495-1501
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• 2012

In this study, an experiment was conducted on influent water with low concentrations of organic matter, such as river water or secondary treatment water of a sewage treatment plant, according to HRT changes by using aerobic biofilm. In the biofilm process, as the biofilm increases in thickness, the inner membrane can be low in oxygen transfer rate and become anaerobic conditions, while the detachment of biomass from biofilm occurs. To overcome these limitations in the detachment of microorganisms in biofilm, the yarn, which was made from poly propylene(PP), was weaved and manufactured into a tube. Then, a test was carried out by injecting air so that the interior of the biofilm could create aerobic conditions. The results of the experiment showed that the removal efficiency of $TCOD_{cr}$ reached 66.1~81.2% by HRT 2hr, and 50.9 ~61.8% after HRT 1 hr. The removal efficiency of $SCOD_{cr}$ was 45.9 to 55.1% by HRT 1hr, and 26.1% in HRT 0.5hr, showing the highest removal efficiency in HRT 1hr. The SS removal efficiency was at 81.8 to 94.6%, and the effluent SS concentration was very low, indicating less than 2.2 mg/L in all HRT's. As a result, the $SCOD_{cr}$ and $NH_4{^+}$-N that were removed per specific surface area and attached to microbial biofilm showed the highest efficiency in HRT 1hr with 8.37 $gSCOD_{cr}/m^2{\cdot}d$, 2.93 $gNH_4{^+}-N/m^2{\cdot}d$. From the result of reviewing the characteristics of biofilm growth, microorganisms were found to be attached, and increased by 36 days. Later, they decreased in number through detachment, but showed a tendency to increase again 41 days later due to microbial reproduction.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.525-528
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• 2008

고에너지 소비형인 시멘트의 대체 재료로써 고로슬래그의 활용성을 높이기 위해 분쇄 방법과 입자의 분말도 그리고 알칼리 자극제의 종류에 따른 50wt.%의 고로슬래그를 치환한 고로 슬래그 시멘트의 수화 및 물리적 특성을 조사하였다. 알칼리 자극제로써 Ca(OH)$_2$, NaOH, Na$_2$SO$_4$,사용하였고 이런 특성들을 비교하기 위해 자극제를 넣지 않은 무첨가 슬래그 시멘트를 함께 실험하였다. 압축강도 실험에서의 분쇄방법에 차이로는 알칼리 자극제에 관계없이 롤러밀로 분쇄한 슬래그가 대체적으로 높은 강도를 나타내었으며 자극제에 따라서는 재령 7일 이내의 초기강도에서는 분말도와 분쇄방법에 관계없이 Na$_2$SO$_4$>Ca(OH)$_2$>None>NaOH 순으로 나왔으며 28일의 장기강도에선 Ca(OH)$_2$가 가장 높게 나타났다.

• 한국세라믹학회지
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• 제52권1호
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• pp.33-40
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• 2015

Onggi, described as a 'breathing' type of pottery' has significantly influenced the traditional food culture of Korea. It is known that Onggi is an optimal type of storage for fermented foods such as soy sauce, salted seafood, and Kimchi, as air or liquid can penetrate through the body of this material. These foods gain flavor due to the breeding of aerobic bacteria at the beginning of the fermentation process. In this study, Onggi materials from five regions, Gangjin, Yeoju, Ulsan, Yesan, and Jeju, were collected and analyzed to determine their chemical and physical properties before and after sintering. The differences in the raw materials of other mining regions are examined in terms of their chemical and mineralogical compositions, specific surface area, particle size, and particle distribution. Among them, the Gangjin raw material has the greatest mean particle size of $92.29{\mu}m$, as well as the widest particle size distribution. Differences in the levels of $SiO_2$ and $Fe_2O_3$ are shown among Onggi raw materials. However, the crystalline phases formed after sintering are identical, except for the Jeju samples. At all sintering temperatures tested here, Gangjin Onggi showed the greatest porosity, leading to complete air permeation through the body within 90 minutes. These results taken together indicate that air permeation is strongly related to the pore structures in the Onggi body. This is assumed to affect the fermentation behavior.

• Journal of Electrochemical Science and Technology
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• 제6권4호
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• pp.121-130
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• 2015

The micro emulsion method has been successfully used for preparing perovskite LaCoO₃ with uniform, fine-shaped nanoparticles showing high activity as electro catalysts in oxygen reduction reactions (ORRs). They are, therefore, promising candidates for the air-cathode in metal-air rechargeable batteries. Since the activity of a catalyst is highly dependent on its specific surface area, nanoparticles of the perovskite catalyst are desirable for catalyzing both oxygen reduction and evolution reactions. Herein, LaCoO₃ powder was also prepared by sol-gel method for comparison, with a broad particle distribution and high agglomeration. The electro catalytic properties of LaCoO₃ and LaCoO₃-carbon Super P mixture layers toward the ORR were studied comparatively using the rotating disk electrode technique in 0.1 M KOH electrolyte to elucidate the effect of carbon Super P. Koutecky-Levich theory was applied to acquire the overall electron transfer number (n) during the ORR, calculated to be ~3.74 for the LaCoO₃-Super P mixture, quite close to the theoretical value (4.0), and ~2.7 for carbon-free LaCoO₃. A synergistic effect toward the ORR is observed when carbon is present in the LaCoO₃ layer. Carbon is assumed to be more than an additive, enhancing the electronic conductivity of the oxide catalyst. It is suggested that ORRs, catalyzed by the LaCoO₃-Super P mixture, are dominated by a 2+2-electron transfer pathway to form the final, hydroxyl ion product.