• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.12
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• pp.1079-1084
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• 2002

Because complex insulation method is used in EHV(extra high voltage) insulation systems, macro Interfaces between two different bulk materials which affect the stability of insulation system exist inevitably. Interface between toughened epoxy and silicone rubber was selected as a interface in EHV insulation systems and tested AC interfacial breakdown properties with variation of many conditions to influence on electrical Properties, such as interfacial pressure, roughness and oil. Specimen was designed to reduce the effect of charge transport from electrode in the process of breakdown and to have the tangential electrical potential with the direction of the interface between epoxy and silicone rubber by using FEM(finite elements method). It could control the interfacial pressure, roughness and viscosity of oil. From the result of this study, it was shown that the interfacial breakdown voltage is improved by increasing interfacial Pressure and oil. In particular, the dielectric strength saturates at certain interracial Pressure level. The decreasing ratio of the interfacial breakdown voltage in non-oiled specimen was increased by the temperature rising, while oiled specimen was not affected by temperature.

• Transactions on Electrical and Electronic Materials
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• v.6 no.3
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• pp.101-105
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• 2005

Electroluminescence(EL) and current-voltage(I-V) characteristics of hybrid EL devices containing Pr and Mn co-doped ZnS nanoparticles were investigated in this study. For the insertion of a hole transport layer of poly (N-vinyl carbazole)(PVK), the current level became lower due to the accumulation of electrons at the interface between PVK and nanoparticles. When both PVK and buffer layer $BaF_2$ were simultaneously introduced, the enhanced EL efficiency and improved I-V characteristics were obtained. This results from the additional increase of hole injection owing to the internal field induced by the significant accumulation of electrons at the interface. The presence of buffer layer $BaF_2$ together with PVK makes it possible the charge accumulation enough to induce the sufficient internal field for further hole injection.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.296-296
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• 2013

Supercapacitor is a capacitor with extraordinarily high energy density, which basically consists of current collector, active material and electrolyte. Ruthenium oxide ($RuO_2$) is one of the most widely studied active materials due to its high specific capacitance and good electrical conductivity. In general, it is known that the coating of $RuO_2$ on nanoarchitectured current collector shows improved performance of energy storage device compared to the coating on the planar current collector. Especially, the surface structure with standing coaxial nanopillars are most desirable since it can provide direct paths for efficient charge transport along the axial paths of each nanopillars and the inter-nanopillar spacing allows easy access of electrolyte ions. However, well-known fabrication methods for metal or metal oxide nanopillars, such as the process using anodize aluminum oxide (AAO) templates, often require long and complicated nanoprocess.In this work, we developed relatively simple method fabricating indium tin oxide (ITO) nanopillars via sputtering. We also electrodeposited $RuO_2$ nanoparticles onto these ITO nanopillars and investigated its physical and electrochemical properties.

• Journal of the Korean institute of surface engineering
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• v.49 no.6
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• pp.490-497
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• 2016

In this study, 3-dimensional ripple structured anion (chlorine) doped ZnO thin film are developed, and used as electron transporting layer (ETL) in inverted organic photovoltaics (I-OPVs). Optical and electrical characteristics of ZnO:Cl ETL are investigated depending on the chlorine doping ratio and optimized for high efficient I-OPV. It is found that optimized chlorine doping on ZnO ETL enhances the ability of charge transport by modifying the band edge position and carrier mobility without decreasing the optical transmittance in the visible region, results in improvement of power conversion efficiency of I-OPV. The highest performance of 8.79 % is achieved for I-OPV with ZnO:Cl-x (x=0.5wt%), enhanced ~10% compared to that of ZnO:Cl-x (x=0wt%).

• KSBB Journal
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• v.8 no.4
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• pp.370-374
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• 1993

In transportation the amount of metal ion by crown ethers, dibenzo-18-crown-6 were investigated using ultraviolet spectrometer. Transported the amount of one valence metal ion as $K^+ and Li^+}$ was not so much. On the other hand, two valence metal ion increased by dibenzo-18-crown-6, which means that the ionic charge and hydration of two valence metal ion affected the carrying ability of crown ethers. The carrying ability of dibenzo-18-crown-6 was, therefore, adequate for two valence metal ion as $Ca^{2+}$ and $Ba^{2+}$. It was also suggested that transport metal ion by crown ethers, which is related rather the catching ability than the selectivity of metalion.

• Computers and Concrete
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• v.15 no.3
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• pp.461-471
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• 2015

The permeability is the most direct indicator to reflect the durability of concrete, and the testing methods based on external electric field can be used to evaluate concrete permeability rapidly. This study aims to use an experiment method to accurately predict the permeability of concrete box beam during service. The ion migration experiments and concrete surface resistivity are measured to evaluate permeability of five concrete box beams, and the relations between these results in service concrete and electric flux after 6 hours by ASTM C1202 in the laboratory are analyzed. The chloride diffusion coefficient of concrete, concrete surface resistivity and concrete 6 hours charge have good correlation relationship, which denote that the chloride diffusion coefficient and the surface resistivity of concrete are effective for evaluating the durability of concrete structures. The chloride diffusion coefficient of concrete is directly evaluated permeability of concrete box beam in service and may be used to predict the service life, which is fit to engineering applications and the concrete box beam is non-destructive. The concrete surface resistivity is easier available than the chloride diffusion coefficient, but it is directly not used to calculate the service life. Therefore the mathematical relation of the concrete surface resistivity and the concrete chloride diffusion coefficient need to be found, which the service life of reinforced concrete is obtained by the concrete surface resistivity.

• ETRI Journal
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• v.33 no.6
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• pp.887-896
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• 2011

We investigated the effects of a gate dielectric and its solvent on the characteristics of top-gated organic field-effect transistors (OFETs). Despite the rough top surface of the inkjet-printed active features, the charge transport in an OFET is still favorable, with no significant degradation in performance. Moreover, the characteristics of the OFETs showed a strong dependency on the gate dielectrics used and its orthogonal solvents. Poly(3-hexylthiophene) OFETs with a poly(methyl methacrylate) dielectric showed typical p-type OFET characteristics. The selection of gate dielectric and solvent is very important to achieve high-performance organic electronic circuits.

• Journal of the Korea Society of Computer and Information
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• v.22 no.6
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• pp.17-24
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• 2017

In recent digital broadcasting, up to 250 channels are multiplexed and transmitted. The channel transmission is made in the form of MPEG-2 Transport Stream (TS) and transmits one channel (Video, Audio). In order to check if many broadcast channels are transmitted normally, in multi-channel multi-view system, ability of real-time monitoring is required. In order to monitor efficient multi-channel, a distributed system in which functions and load are distributed should be implemented. In the past, we used an inefficient system that gave all of the functionality to a piece of hardware, which limited the channel acceptance and required a lot of resources. In this paper, we implemented a distributed multi-view system which can reduce resources and monitor them economically through efficient function and load balancing. It is able to implement efficient system by taking charge of decoding, resizing and encoding function in specific server and viewer function in separate server. Through this system, the system was stabilized, the investment cost was reduced by 19.7%, and the wall monitor area was reduced by 52.6%. Experimental results show that efficient real-time channel monitoring for multi-channel digital broadcasting is possible.

• Journal of Navigation and Port Research
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• v.31 no.2
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• pp.133-139
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• 2007

Relative importance of maritime transport that takes charge of main current of freight in country' economy is very large. Especially, port and facility carry out important role which treats freight of import and export smoothly and improves international trade as turning point, to achieve key role on connection and association between sea and land. For such reason, enlargement of port facilities or development of port needs to grasp exactly the utilization of port, attributes and selective factors of shipper. On the other hand, the amounts of physical distribution on Mokpo port located in Korean west coast are increasing, with fast economic growth of East Asian including China. This study uses discrete choice model that is measuring to analyze attribute and characteristic of Mokpo port, and analyzes port selection by decision factors of shipper. This paper composed a questionnaire using the result of preceding research, to decide port selection factor among competitive ports. Through factor analysis on a basis of the questionnaire' result, five principal components were extracted. These are resorted out by Logit model, to grasp competitive elements of port. This research fin present direction which raises competitive power of ports in west coast of Korea, especially on alternative and concentration of middle-class port as Mokpo may be useful.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.181-184
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• 2004

Organic semiconductors have attracted considerable attention due to their interesting physical properties followed by various technological applications in the area of electronics and opto-electronics. It has been a long time since organic solar cells were expected as a low-cost high-energy conversion device. Although practical use of them has not been achieved, technological progress continues. Morphology of the materials, organic/inorganic interface, metal cathodes, molecular packing and structural properties of the donor and acceptor layers are essential for photovoltaic response. We have fabricated solar-cell devices based on copper-phthalocyanine(CuPc) as a donor(D) and fullerene($C_{60}$) as an electron acceptor(A) with doped charge transport layers, and BCP as an exciton blocking layer(EBL). We have measured photovoltaic characteristics of the solar-cell devices using the xenon lamp as a light source.