• 한국세라믹학회지
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• 제43권12호
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• pp.805-811
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• 2006

The microstructural changes in Ni/YSZ anode substrate and crack formation during Ni oxidation were investigated. The composition of as-sintered anodes was 56 wt% NiO+44 wt% YSZ and that of electrolyte was 8 mol% yttria. After complete reduction, specimens were oxidized in $N_2$ + air at $600\sim800^{\circ}C$. Oxygen partial pressure was controlled in between 0.05 atm and 0.2 atm $O_2$. When the anode was oxidized, at higher than $690^{\circ}C$, three layers were formed in the specimens. The first was fully oxidized layer(NiO/YSZ), the second was a mixed layer and the third, near-intact layer. Under $640^{\circ}C$ such distinctive layers were not observed. Cracks formed at electrolyte layer when weight gain attained at $65\sim75%$ of the total gain due to complete oxidation despite of different oxidation temperature and oxygen partial pressure.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.159-159
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• 2008

Indium-tin oxides (ITO) films have been widely used as transparent electrodes for optoelectronic devices such as organic light emitting diodes (OLEDs), photovoltaics, touch screen devices, and flat-paneldisplay. In particular, to improve hole injection efficiency in OLEDs, transparent electrodes should have high work-function besides their transparency and low resistivity. Nevertheless, few studies have been made on engineering the work function of ITO for use as an efficient anode. In this study, the effects of a wide range of Nb or Zn doping rate on the changes in work functions of ITO anode were investigated. The Nb or Zn doped ITO films were fabricated on glass substrates using combinatorial sputtering system which yields a linear composition spread of Nb or Zn concentration in ITO films in a controlled manner by co-sputtering two targets of ITO and Nb2O5 or ITO and ZnO. We have also examined the resistivity, transmittance, and other structural properties of the Nb or Zn-doped ITO films. Furthermore, OLEDs employing Nb or Zn-doped ITO anodes were fabricated and the device performances were investigated concerned with the work function changes.

• Bulletin of the Korean Chemical Society
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• 제34권5호
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• pp.1435-1440
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• 2013

To investigate the influence of the carbon matrix on the electrochemical performance of Si/C composites, four types of Si/C composites were prepared using graphite, petroleum coke, pitch and sucrose as carbon precursors. A ball mill was used to prepare Si/C blends from graphite and petroleum coke, whereas a dispersion technique was used to fabricate Si/C composites where Si was embedded in disordered carbon matrix derived from pitch or sucrose. The Si/pitch-based carbon composite showed superior Si utilization (96% in the first cycle) and excellent cycle retention (70% after 40 cycles), which was attributed to the effective encapsulation of Si and the buffering effect of the surrounding carbon matrix on the silicon particles.

• 대한화학회지
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• 제57권3호
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• pp.316-321
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• 2013

Electrocoagulation (EC) technique is applied for the treatment of wastewater containing heavy metals ions such as nickle (Ni), lead (Pb) and cadmium (Cd) by using sacrificial anodes corrode to release active coagulant flocs usually aluminium or iron cations into the solution. During electrolytic reactions hydrogen gas evolve at the cathode. All the experiments were carried out in Batch mode. The tank was filled with synthetic wastewater containing heavy metals and efficiency of electro-coagulation in combination with aluminum and iron electrodes were investigated for removal of such metals. Several parameters, such as contact time, pH, electro-coagulant concentration, and current density were optimized to achieve maximum removal efficiency (%). The concentrations of heavy metals were determined by using Atomic Absorption Spectroscopy (AAS). It is found that the electro-coagulation process has potential to be utilized for the cost-effective removal of heavy metals from wastewater specially using iron electrodes in terms of high removal efficiencies and operating cost.

• Corrosion Science and Technology
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• 제7권4호
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• pp.197-200
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• 2008

In this paper, physical scale modeling was employed to identify the configurations of ICCP system and the electric field signatures. Computational boundary element modeling technique has been used to simulate the performance of the CP system and to predict the associated electric fields signatures. The optimization methods combined with the computer models and physical scale modeling will be presented here, which enable the optimum system design to be achieved both in terms of the location and current output of the anode but also in the location of reference electrodes for impressed current cathodic protection(ICCP) systems. The combined methodology was utilized to determine optimal placement of ICCP components (anodes and reference electrodes) and to evaluate performance of ICCP system for the 2%, 10% and 14% wetted hull coatings loss. The objective is to design the system to minimise the electric field while at the same time provide adequate protection for the ship. The results show that experimental scale modeling and computational modeling techniques can be used in concert to design an optimum ICCP system and to provide information for quickly analysis of the system and its surrounding environment.

• Corrosion Science and Technology
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• 제10권2호
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• pp.71-75
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• 2011

Corrosion properties of Al-0.3Ga-0.3Sn, Al-0.3Mn-0.3Ga, and Al-0.3Mn-0.3Sn alloys were examined to develop an anode material for Al-air battery with alkaline aqueous or ethanol electrolyte. The results of potentiodynamic polarization tests showed that the electrode potential of the Al alloys were lower than the pure Al, implying the cell voltage can be increased by using one of these alloys for an anode in 4 M KOH aqueous solution. The corrosion rate appeared to be increased by alloying Ga but to be reduced by Sn and Mn in the aqueous solution. The ethanol solution is expected to improve the cell performance in that the electrode potential and the corrosion rate of Al were lower in ethanol solution than in aqueous solution. However the Al-(Ga, Sn, Mn) alloys are not favorable in ethanol solution because of the high potential and corrosion rate.

• 한국세라믹학회지
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• 제52권5호
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• pp.325-330
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• 2015

Performance of solid oxide fuel cells (SOFCs), in comparison with that under hydrogen fuel, were investigated under direct internal reforming conditions. Anode supported cells were fabricated with an Ni+YSZ anode, YSZ electrolyte, and LSM+YSZ cathode for the present work. Measurements of I-V curves and impedance were conducted with S/C (steam to carbon) ratio of ~ 2 at $800^{\circ}C$. The outlet gas was analyzed using gas chromatography under open circuit condition; the methane conversion rate was calculated and found to be ~ 90% in the case of low flow rate of methane and steam. Power density values were comparable for both cases (hydrogen fuel and internal steam reforming of methane), and in the latter case the cell performance was improved, with a decrease in the flow rate of methane with steam, because of the higher conversion rate. The present work indicates that the short-term performance of SOFCs with conventional Ni+YSZ anodes, in comparison with that under hydrogen fuel, is acceptable under internal reforming condition with the optimized fuel flow rate and S/C ratio.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.416-417
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• 2007

We prepared flexible transparent conducting electrodes by spray coating of single-walled carbon nanotube (SWNT) networks on PET substrate and have demonstrated their use as transparent anodes for flexible organic light emitting diodes (OLEDs). The flexible CNT electrode produced by spray coating method shows relatively low sheet resistance ($150{\sim}220{\Omega}/sq.$) and high transmittance of ~60% even though it was prepared at room temperature. In addition, CNT electrode/PET sample exhibits little resistance change during 2000 bending cycles, demonstrated good mechanical robustness. Using transparent CNT electrode, it is readily possible to achieve performances comparable to commercial ITO-based OLEDs. This indicates that flexible CNT electrode is alternative anode materials for conventional ITO anode in flexible OLEDs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.273-275
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• 2005

The national need to establish a new stray current mitigation method to protect the underground metallic infrastructures in congested downtown area forced us to design and develop the distributed impressed current cathodic protection (DICCP) system. The main purpose of this system is to replace the stray current drainage bond methods, which is widely adopted by pipeline owners in Korea. Currently, forced drainage makes up about 85% of total drainage facilities installed in Korea because polarized drainage can neither drain perfectly the stray currents during normal operation of electric vehicle nor drain the reverse current during regenerative braking at all. The forced drainage, however, has been abused as an alternative cathodic protection system, which impresses currents from rails to the pipelines and accordingly uses the rails as anodes. As a result, it is necessary to consider a new method to both cathodically protect the pipelines and effectively drain the stray currents. In this paper, we describe the design parameters and installation schemes of DICCP system that can meet these demands.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.319.1-319.1
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• 2013

Solid oxide fuel cells (SOFCs) have been recognized as one of emerging renewable energy sources, due to minimized pollutant production and high efficiency in operation. The performance of SOFCs is largely dependent on the electrode polarization which involves the oxidation/reduction in cathodes and anodes along with the charge transport of ions and electronic carriers. Atomic layer deposition is based on the alternate chemical surface reaction occurring at low temperatures with high uniformity and superior step coverage. Such features can be extended into the coating of metal oxide and/or metal layer onto the porous materials. In particular, the atomic layer deposition is can manipulated in controlling the charge transport in terms of triple phase boundaries, in order to control artificially the electrochemical polarization in electrodes of SOFC. The current work applied atomic layer deposition of metal oxides intro the electrodes of SOFCs. The corresponding effect was monitored in terms of the electrochemical characterization. The roles of atomic layer deposition in solid oxide fuel cells are discussed towards optimized towards long-term durability at intermediate temperature.