• Corrosion Science and Technology
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• 제21권5호
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• pp.412-417
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• 2022

Proton exchange membrane fuel cells (PEMFCs) provide zero emission power sources for electric vehicles and portable electronic devices. Although significant progresses for the widespread application of electrochemical energy technology have been achieved, some drawbacks such as catalytic activity, durability, and high cost of catalysts still remain. Pt-based catalysts are regarded as the most efficient catalysts for sluggish kinetics of oxygen reduction reaction (ORR). However, their prohibitive cost limits the commercialization of PEMFCs. Therefore, we proposed a NiCo@Au core shell structure as Pt-free ORR electrocatalyst in PEMFCs. NiCo alloy was synthesized as core to introduce ionization tendency and autoxidation reaction. Au as a shell was synthesized to prevent oxidation of core NiCo and increase catalytic activity for ORR. Herein, we report the synthesis, characterization, electrochemical properties, and PEMFCs performance of the novel NiCo@Au core-shell as a catalyst for ORR in PEMFCs application. Based on results of this study, possible mechanism for catalytic of autoxidation core@anti-oxidation shell in PEMFCs is suggested.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2009년도 제41차 학술발표회
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• pp.103-104
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• 2009

Treatment of wool fabric with aromatic aldehydes followed by oxidation with hydrogen peroxide gave rise to coloring reaction. The colored fabric was bleached by reduction and recovered the color by oxidation. The oxidation in ethanol solution gave higher k/s values than that in aqueous solution. Photo-stability of the colored fabric was improved by treating with nickel sulfate.

• Journal of Microbiology and Biotechnology
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• 제26권4호
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• pp.757-762
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• 2016

The group of Fe(III) oxide-reducing bacteria includes exoelectrogenic bacteria, and they possess similar properties of transferring electrons to extracellular insoluble-electron acceptors. The exoelectrogenic bacteria can use the anode in microbial fuel cells (MFCs) as the terminal electron acceptor in anaerobic acetate oxidation. In the present study, the anodic community was compared with the community using Fe(III) oxide (ferrihydrite) as the electron acceptor coupled with acetate oxidation. To precisely analyze the structures, the community was established by enrichment cultures using the same inoculum used for the MFCs. High-throughput sequencing of the 16S rRNA gene revealed considerable differences between the structure of the anodic communities and that of the Fe(III) oxide-reducing community. Geobacter species were predominantly detected (>46%) in the anodic communities. In contrast, Pseudomonas (70%) and Desulfosporosinus (16%) were predominant in the Fe(III) oxide-reducing community. These results demonstrated that Geobacter species are the most specialized among Fe(III)-reducing bacteria for electron transfer to the anode in MFCs. In addition, the present study indicates the presence of a novel lineage of bacteria in the genus Pseudomonas that highly prefers ferrihydrite as the terminal electron acceptor in acetate oxidation.

• 한국세라믹학회지
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• 제43권3호
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• pp.173-176
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• 2006

${Sr_{1-x}Ba_xNb_2O_6$(SBN) have been obtained in Pt crucible by melting and cooling in air atmosphere. Some SBNs being at the bottom of the crucible are black and transparent, and the other SBNs colorless. The black SBN became to be colorless by oxidation heat treatment $1,300^{\circ}C$ for 4 h, Curie temperature is changed by colorless change of black SBN. The reason seems to be $Nb^{5+}$ oxidation of some $Nb^{4+}$ ions in SBN or effect of unknown impurities. Diffused Phase Transition (DPT) was appeared during heating and cooling process. Various sintered SBN ceramics specimen showed relaxor characteristics.

• Journal of Electrochemical Science and Technology
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• 제7권2호
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• pp.91-96
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• 2016

Oxidation behaviours of ash free coal (AFC), carbon, and H₂ fuels were investigated with a coin type molten carbonate fuel cell. Because AFC has no electrical conductivity, its oxidation occurs via gasification to H₂ and CO. An interesting behaviour of mass transfer resistance reduction at higher current density was observed. Since the anode reaction has the positive reaction order of H₂, CO₂ and H₂O, the lack of CO₂ and H₂O from AFC results in a significant mass transfer resistance. However, the anode products of CO₂ and H₂O at higher current densities raise their partial pressure and mitigate the resistance. The addition of CO₂ to AFC reduced the resistance sufficiently, thus the resistance reduction at higher current densities did not appear. Electrochemical impedance results also indicate that the addition of CO₂ reduces mass transfer resistance. Carbon and H₂ fuels without CO₂ and H₂O also show similar behaviour to AFC: mass transfer resistance is diminished by raising current density and adding CO₂.

• 대한한방내과학회지
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• 제24권2호
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• pp.203-212
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• 2003

Objective : As a link in chain of research to confirm the oriental medical prescription which has the anti-atherosclerosis effects, this research evaluated the effects on the macrophage-related factors by using KanghwalSokdantang(KS). Methods : In order to perform this research, we have evaluated the effects on the oxLDL formation from the macrophages, the nitric oxide formation, and the oxidation of macrophages. Thus, with this evaluation, we have investigated the applicapability on the artherosclerosis. Results : KanghwalSokdantang has showed a noticeable reduction of protein oxidation in the process of oxLDL formation, has remarkably restrained phospholipid peroxidation, an index to estimated the phospholipid oxidation and reduction that are formed in the process of macrophage's oxLDL formation, and has increased the nitrite concentration noticeably in the LDL-dealing macrophages. By increasing the survival rate of macrophages, KanghwalSokdantang has restrained the cellular damages. KanghwalSokdantang is ineffective on the LDH outflow from damaged cells. $1{\mu}g/ml$ KanghwalSokdantang sample has increased acid phosphatase activity remarkably. Conclusion : KanghwalSokdantang has the possibility to be used in the prevention and treatment of atherosclerosis, which is formed by the oxLDL formation of macrophages.

• 한국자동차공학회논문집
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• 제6권3호
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• pp.138-142
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• 1998

Among aftertreatment devices which reduce exhaust gas of diesel engine, diesel oxidation catalyst(DOC) with high reduction efficiency for gaseous matter and particulate matter is now being studied actively. In this study, an experiment was conducted to analyze the effects of low sulfur diesel fuel in heavy duty diesel engine equipped with DOC. We tested to estimate change of engine performance for the low and high sulfur diesel fuels in a 11,000cc diesel engine equipped with DOC. We conducted test to estimate the reduction efficiency of exhaust gas in D-13 mode of heavy duty diesel regulation mode and in smoke opacity mode for two samples of high sulfur content (0.2%) and low sulfur content(0.05%)

• 한국생산제조학회지
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• 제9권3호
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• pp.136-142
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• 2000

With the significant growth of the number of vehicles environmental problems is raised. NOx SOx, and PM emissions in diesel powered vehicles are larger than that in gasoline because the development of pollutants reduction techniques has not been yet achieved. So it is need to develop after-tratment or to convert into alternative fuel to satisfy emission regula-tion. Among the after-treatment systems to reduce the diesel emissions studies with diesel oxidation catalyst(DOC) are done greatly. In this study using DOC reduction efficiency with the change of temperature and catalyst loading was calculated through measurements of CO, HC, PM. and SOX.

• KSBB Journal
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• 제19권2호
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• pp.154-158
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• 2004

본 논문에서는 회분식 반응기에서 초기 산화환원전위가 ＋40 mV에서 -70 mV으로 낮아짐에 따라 탈질 속도는 1.25 mg/min에서 3.33 mg/min으로 증가하였고, 또한 회분식 반응기에서 질산성질소의 농도가 200 mg/1까지 증가할수록 nitrite의 축적없이 탈질 속도가 초기 농도에 비례적으로 증가하였다. 반면, 질산성질소의 농도가 400 mg/1가 되면 탈질 속도의 변화는 없으나 nitrite의 축적이 발생하기 시작하였으며, 질산성질소의 농도가 1,000 mg/l로 증가할 경우에는 많은 양의 nitrite가 축적이 되어 탈질의 저해가 발생하여 탈질 속도가 감소하였다. 회분식 반응기의 결과를 바탕으로, 충전탑식 반응기에서 유입수의 초기 산화환원전위를 낮추기 위하여 유출수를 재순환시킨 결과, 유입수의 초기 산화화원전위를 150 mV에서 30 mV로 낮출 수 있었고, 유입수의 초기 질산성질소의 농도를 120 mg/l에서 85 mg/l까지 낮출 수 있었다. 그 결과 충전탑식 반응기에서 유출되는 질산성질소의 농도가 재순환을 하기 전에는 약 61 mg/l이었으나, 유출수의 재순환으로 질산성질소의 농도를 10 mg/l까지 낮출 수 있었고, 질산 성질소의 제거율을 49.2%에서 91.7%로 증가시킬 수 있었다.

• 마이크로전자및패키징학회지
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• 제11권3호
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• pp.55-62
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• 2004

여러 가지 온도와 습도에 따라 Sn의 표면에 형성되는 산화물을 전기화학적 환원방법을 이용해 분석하였다. 전기화학적 방법을 이용하여 금속표면에 형성된 산화물을 환원시킬 때 나타나는 환원전위와 소모된 전하량을 측정하여 표면 산화물의 종류와 양을 정량적으로 분석하였다 우선 전기화학적 환원 방법이 금속 표면 산화물의 분석에 적합한지 알아보기 위해 여러 가지 산화물 분말의 환원 전위와 수소 발생 전위를 측정하였고, 분석을 위한 최적의 전류밀도 값을 구하였다. Sn 표면에 생성된 산화물을 분석한 결과 $85^{\circ}C$의 건조한 환경에서 보다 T/H (Temperature/Humidity, $85^{\circ}C$/$85\%$상대습도)조건에서 SnO가 더 빠르게 성장하였다. 또한 T/H 조건에서 하루가 지난 이후부터는 Sn의 표면 최상층에 매우 얇은 (<10 ${\AA}$) $SnO_2$ 가 형성되어 있는 것을 확인하였다. $150^{\circ}C$에서는 SnO와 $SnO_2$가 같이 존재하는 것을 확인하였다. 또한 XPS와 AES 표면분석을 통하여 환원 실험 결과를 뒷받침하였다.