• 한국세라믹학회지
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• 제50권1호
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• pp.25-30
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• 2013

The pore volume of hardened cement with waterproofing materials is lower compared to that of hardened cement without waterproofing materials. Thus, fewer gaps will appear by means of chemical reactions between $Ca^{2+}$ ions in hardened cement and water, solutes, and other ions. Due to the selective permeability, the osmotic pressure of hardened cement can change due to physical effects such as the reduction of the pore volume and the reduction in the number of pores, as well as by the electrochemical reaction between water, solutes, other ions and $Ca^{2+}$ ions in hardened cement. Of course, these factors do not have independent effects but instead a combined complex effect. Accordingly, we studied changes in the osmotic pressure due to the difference in the pore structure of hardened cement. A pore size smaller than 1 nm in hardened cement had only a slight effect on the osmotic pressure, whereas a pore size larger than 1 nm had a direct effect on the osmotic pressure.

• 공업화학
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• 제26권3호
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• pp.239-246
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• 2015

나노 탄소재료를 복합화하면 기존 재료의 특성을 유지하면서 그 효율을 극대화할 수 있다. 여기에 이종원소를 부가하면 전기화학적인 특성이 디자인되므로, 나노 탄소재료의 복합화를 통해 한 종류의 나노 재료로부터 여러 강점을 얻을 수 있다. 특히 탄소나노섬유와 금속산화물을 복합화하면 탄소나노섬유의 전기이중층 뿐만 아니라 금속산화물의 산화 환원 반응을 이용하여 비축전 용량, 고율 특성, 수명 특성이 향상되고 높은 수준의 출력밀도가 유지되는 고용량 슈퍼 캐퍼시터용 전극 소재를 개발할 수 있다. 본 총설에서는 탄소의 고출력특성과 금속산화물의 고에너지 특성이 동시에 발현되는 금속산화물계 탄소나노섬유복합체의 제법과 응용에 대한 최신연구를 다루도록 하겠다.

• Bulletin of the Korean Chemical Society
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• 제24권4호
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• pp.437-440
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• 2003

In a mediator-aided microbial fuel cell, the choice of a proper mediator is one of the most important factors for the development of a better fuel cell system as it transfers electrons from bacteria to the electrode. The electrochemical behaviors within the lipid layer of two representative mediators, thionin and safranine O both of which exhibit reversible electron transfer reactions, were compared with the fuel cell efficiency. Thionin was found to be much more effective than safranine O though it has lower negative formal potential. Cyclic voltammetric and fluorescence spectroscopic analyses indicated that both mediators easily penetrated the lipid layer to pick up the electrons produced inside bacteria. While thionin could pass through the lipid layer, the gradual accumulation of safranine O was observed within the layer. This restricted dynamic behavior of safranine O led to the poor fuel cell operation despite its good negative formal potential.

• 한국산학기술학회논문지
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• 제11권6호
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• pp.2306-2310
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• 2010

상수도관의 부식은 수돗물이 공급되는 과정에서 관 표면의 금속과 물 사이의 일련의 복잡한 산화/환원 반응이다. 부식으로 인해 발생할 수 있는 1차적인 고려사항은 철, 납, 동과 같은 독성이 있는 중금속이 물속에 존재할 수 있다는 것이며, 이는 상수도관에 악영향을 미치며, 세탁물을 훼손하거나 맛을 낼 수 있는 심미적인 문제도 발생된다. 본 연구에서는 부식억제제가 상수도관의 부식도, 수돗물 중의 철 및 동의 용출 농도에 어떠한 영향을 미치는지에 대해서 평가하였다. 부식저감 효과는 인산염계 부식억제제와 큰 관련성이 있었다. 부식반응은 물과 관의 표면에서 이루어지는 일련의 전기화학적인 반응임을 고려하면 철의 용출농도와 부식도는 양(+)의 상관관계에 있다.

• Journal of Microbiology and Biotechnology
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• 제22권11호
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• pp.1471-1477
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• 2012

Carotenoids produced by non-photosynthetic bacteria protect organisms against lethal photodynamic reactions and scavenge oxygenic radicals. However, the carotenoid produced by Gordonia alkanivorans SKF120101 is coupled to reducing power generation. SKF120101 selectively produces carotenoid under light conditions. The growth yield of SKF120101 cultivated under light conditions was higher than that under dark condition. In the cyclic voltammetry, both upper and lower voltammograms for neutral red (NR) immobilized in intact cells of SKF120101 were not shifted in the condition without external redox sources but were commonly shifted downward by glucose addition and light. Electric current generation in a biofuel cell system (BFCS) catalyzed by harvested cells of SKF120101 was higher under light than dark condition. The ratio of electricity generation to glucose consumption by SKF120101 cultivated in BFCS was higher under light than dark condition. The carotenoid produced by SKF120101 catalyzes production of reducing power from light energy, first evaluated by the electrochemical technique used in this research.

• Bulletin of the Korean Chemical Society
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• 제35권6호
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• pp.1639-1646
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• 2014

A series of novel fused-ring spiro compounds, spiro[benzo[ij]tetraphene-7,9'-fluorene] (SBTF) derivatives containing an end-capping aryl substituent at both the C3 and C10-positions hasbeen designed and synthesized via multi-step Suzuki coupling reactions. 3-(1-Naphthyl)-10-phenylSBTF (1N-PSBTF), 3-(2-naphthyl)-10-phenylSBTF (2N-PSBTF) and 3-[4-(1-naphthyl)phenyl]-10-phenylSBTF (NP-PSBTF) showed improved glass transition temperatures ($T_g$) with good thermal stability. Their photophysical, electrochemical, and electroluminescent properties were investigated and were used to construct blue organic light emission diodes (OLEDs). The typical OLED devices showed excellent performance; the NP-PSBTF-based device exhibited highly efficient deep blue-light emission with a maximum efficiency of 5.27 cd/A (EQE, 4.63%) with CIE (x = 0.133, y = 0.144). According to these characteristics, these deep-blue light emitting materials have sufficient potential for fluorescent OLED applications.

• 한국수소및신에너지학회논문집
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• 제29권1호
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• pp.56-63
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• 2018

In this study, a $100cm^2$ cell frame for a molten carbonate fuel cell was designed using CFD analysis. Electrochemical reactions, gas flow, and the heat transfer in $100cm^2$ cell frame were modeled using COMSOL Multiphysics. Two design variables such as the height of the cell frame and the length of the gas input area were determined to obtain minimized temperature distribution and uniform gas distribution. With two design parameter such as height of the cell frame and the length of the gas flow channel, the temperature difference in the cell fame was decreased to $5^{\circ}C$ and the gas uniformity in the flow channel were achieved.

• 한국수소및신에너지학회논문집
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• 제21권1호
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• pp.35-41
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• 2010

Water management is an important issue of PEM fuel cell operation. Water is the product of the electrochemical reactions inside fuel cell. If liquid water accumulation becomes excessive in a fuel cell, water columns will clog the gas flow channel. This condition is referred to as flooding. A number of researchers have examined the water removal methods in order to improve the performance. In this paper, a new water removal method that investigates the use of vibro-acoutic methods is presented. Piezo-actuators which are devices to generate the flexural wave are attached at the end of a cathode bipolar plate. Flexural wave is used to impart energy to resting droplets and thus cause movement of the droplets in the direction of the traveling wave.

• 한국수소및신에너지학회논문집
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• 제24권2호
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• pp.172-178
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• 2013

This study examined the electrochemical deposition and dissolution of lithium on nickel electrodes in 1 mol $dm^{-3}$ (M) $LiPF_6$ dissolved in propylene carbonate (PC) containing different 1,2-dimethoxyethane (DME) concentrations as a co-solvent. The DME concentration was found to have a significant effect on the reactions occurring at the electrode. The poor cycleability of the electrodes in the pure PC solution was improved considerably by adding small amounts of DME. This results suggested that the dendritic lithium growth could be suppressed by using co-solvents. After hundredth cycling in the 1 M $LiPF_6$/PC:DME (67:33) solution, almost no dead lithium has been found from the disassembled cell, resulting from suppression of dendritic lithium growth. Scanning electron microscopy revealed that dendritic lithium formation was greatly affected by the ratio of DME. Raman spectroscopy results suggested that the structure of solvated lithium ions is a crucial important factor in suppressing dendritic lithium formation.

• Mycobiology
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• 제36권4호
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• pp.260-265
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• 2008

Cyclic voltammetric measurements were performed for Co(II), Ni(II), Cu(II) and Zn(II) complexes of 1 : 1 alternating copolymer, poly(3-nitrobenzylidene-1-naphthylamine-co-succinic anhydride) (L) and Ni(II) and Cu(II) complexes of 1 : 1 alternating copolymer, poly(3-nitrobenzylidene-1-naphthylamine-co-methacrylic acid) ($L^1$). The in vitro biological screening effects of the investigated compounds were tested against the fungal species including Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans and bacterial species including Staphylococcus aureus, Escherichia coli, Klebsiella pneumaniae, Proteus vulgaris and Pseudomonas aeruginosa by well diffusion method. A comparative study of inhibition values of the copolymers and their complexes indicates that the complexes exhibit higher antimicrobial activity. Copper ions are proven to be essential for the growth-inhibitor effect. The extent of inhibition appeared to be strongly dependent on the initial cell density and on the growth medium. The nuclease activity of the above metal complexes were assessed by gel electrophoresis assay and the results show that the copper complexes can cleave pUC18 DNA effectively in presence of hydrogen peroxide compared to other metal complexes. The degradation experiments using Rhodamine B dye indicate that the hydroxyl radical species are involved in the DNA cleavage reactions.