• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1258_1259
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• 2009

염료감응형 태양전지 (dye-sensitized solar cell; DSC)는 경제성 한계에 달한 Si 태양전지를 대체할 수 있는 유력한 후보로서, 지금까지 많은 연구개발로 큰 효율향상을 기록했다. 다양한 연구 분야 중에서도, 투명전도성 막과 전해질 층간의 접촉으로 발생하는 전자의 재결합을 막기 위해 삽입하는 compact layer는 ZnO dip-coating, $TiCl_4$ dip-coating, Ti sputtering 등 다양한 제조방법이 제시되었다. 본 연구에서는 $TiCl_4$ 용액을 이용해 spin-coating 방법으로 $TiO_2$ compact layer를 제조하는 시도를 했다. 기존 dip-coating 방법과의 비교를 통해서 본 연구의 spin-coating 방법에 의한 효과를 확인한 결과, standard DSC 대비 33.4%, dip-coating 방법으로 compact layer를 삽입한 DSC 대비 6%의 효율 향상을 기록했다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.11 no.1
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• pp.67-75
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• 1993

The urban expansion and the modernization of the urban infrastructure need a new technology to manage the facilities. The sewer management, one of the urban infrastructures, requires geographical information systems(GIS) for this purpose, and can be supported by the expert system. Consequently, non-professionals can use this system conveniently. In this study, the search and retrieving capacity of the relational database management system(DBMS) and the chain topology generator of the vector-based GIS were integrated into the sewer management system together with the expert knowledge. This system can predict the sewer volume charge by the simulation, and automate these procedures. This system is also user-friendly by using the user-interface. Finally, the system was applied to one of the Seoul drainage districts and tested.

• Journal of the Korea Computer Industry Society
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• v.7 no.4
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• pp.421-426
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• 2006

Because the 3-Tier structure cia share a business logic, the reuse of existing code could be guaranteed Al so tiny and little client application in charge of user interface can he made that it doesn't need plenty of client memory and calculation capability. Catering system that capable of meal material code management autom atic production of requiring quantity, purchase and shipping management menu management, account management was developed for grafting 3-Tire structure technology using database language and ADO(ActiveX Dat a Object). This system improved production in field of school lunch program and saved o(poises. finally, this system is suitable to the service environment of school lunch program and lots of utilizations would be anticipated.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.11
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• pp.1323-1328
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• 1988

Thermally grown $SiO_2$ films on silicon have been thermally nitrided in the $NH_3$ gas ambient and their properties have been investigated by analyzing the AES data and the results of the I-V and the C-V measurements. The Auger depth profile show that the nitrogen-rich layers are formed at the nitrided oxide film surface and near the $SiO_2$-Si interface. The higher the nitridation temperature is, the larger the refractive index of nitroxide film is. And the thinner the oxide film to be nitrided for the same nitridation temperature is, the larger the refractive index of nitroxide film is. When thin $SiO_2$ film is thermally nitrided, the I-V characteristics show the Fowler-Nordheim conduction fashion. Flatband voltages of $SiO_2$ films are shifted by nitridation, due to the fixed charge formation.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.12
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• pp.39-46
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• 1996

In AlGaAs/GaAs HBT the temperature dependence of DC parameters was investigated over the temperature range between 95K and 580K. The temperature dependence of DC parameters depends on the relative contribution of each of the current components suc as emitter-injection-current, base-injection-current, bulk recombination current, interface recombination curretn, thermal generation ecurrent and avalanche current due to impact ionization within the collector space charge layer in a specific temperature. In this paper we investigated the temperature effects on DC parameters such as V$_{BE,ON}$ current gain, input and output characteristics, V$_{CE, OFF}$, R$_{E}$, R$_{C}$ and analyzed the origins, and extracted the qualitativ econditions for a stable HBTs against the temperature variation. Finally, in order to keep HBTs stable with respect to the variation of temperature, the valance-band-energy-discontinuity at emitter-base heterojunction should be large enough to enhance the effect of carrier suppression at a relatively high temperature. In addition the recombination centers, especially around collector junction, should be removed and the area of emitter and collector junction should be identical as well.

• Applied Chemistry for Engineering
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• v.8 no.4
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• pp.667-672
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• 1997

Thermal behavior of high capacity Nickel/Metal hybride battery in analyzed using the NISA software which is based on the three dimensional finite element method. Differential energy balance equation is used for the conduction heat transfer of the battery, while convective heat transfer equation is used for the interface between the battery and air. Heat generation rate and convective heat transfer coefficient are tested as variables to investigate thermal behavior, and the generalized equation for maximum temperature inside the battery is developed. The abrupt rise of the battery temperature due to the quick charge or discharge can be prevented from the use of metallic cooling fin. In addition, temperature augmentation of the battery is negligible when the low thermal conductive and thin insulating material is used outside of the battery case.

• Journal of Information Display
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• v.11 no.1
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• pp.1-7
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• 2010

The intermediate connectors play crucial roles in the performance of tandem organic light-emitting diodes (OLEDs) because they are required to facilitate charge carrier transport and to guarantee transparency for light transmission and deposition compatibility. Understanding the physical properties of the intermediate connector is not only fundamentally important but is also crucial to developing high-efficiency organic devices with a tandem structure. In this study, several effective intermediate connectors in tandem OLEDs using a doped or non-doped organic p-n heterojunction were systematically investigated by studying their interfacial electronic structures and corresponding device characteristics. The working mechanisms of the intermediate connectors are discussed herein by referring to their relevant energy levels with respect to those of the neighboring organic layers. The factors affecting the operation of the intermediate connectors in tandem OLEDs, as demonstrated herein, provide guidance for the identification of new materials and device architectures for high-performance devices.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.3
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• pp.161-167
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• 2018

In battery-operated systems, an isolated converter is used to interface the utility grid with the system to increase stability when charging and discharging batteries. Systems such as vehicle-to-grids (V2Gs), on-board chargers, and energy storage systems (ESSs) have recently become popular, and the roles of isolated converters have become important considerations in fabricating such devices. A fixed-frequency LLC converter, which is a type of isolated converter, presents the advantages of high efficiency and high power density by performing zero-voltage switching (ZVS) over wide frequency ranges. However, the magnetizing inductance of the LLC converter should be designed to enable ZVS in all switching devices. Therefore, in this study, the operating characteristics of the LLC circuit are analyzed, and an optimal design method for ZVS operation is established. Moreover, an 8 kW LLC high-efficiency and high-power-density resonant converter is designed and tested for ESS application. The LLC converter achieves 98% efficiency at rated power.

• The Korean Journal of Ceramics
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• v.5 no.4
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• pp.353-356
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• 1999

Highly proten-conductive elastic composites have been successfully prepared from $H_3PO_4$-doped silica gel and styrene-ethylene-butylene-styrene block elastic copolymer. In addition solid state electric double-layer capacitors have been fabricated using the composite as an electrolyte and activated carbon powders(ACP) hybridized with the composite as a polrizable electrode. The cyclic voltammogram of the electric double-layer capacitor fabricated demonstrated that electric charge was stored in the elecric double-layer at the interface between the polarizable electrode and the electrolyte. The value of capacitance of the capacitor was 10 F/(gram of total ACP), which was comparable to that of the capacitors using conventional liquid electrolytes.

• Journal of the Korean Electrochemical Society
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• v.10 no.3
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• pp.179-183
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• 2007

The corrosion behavior of metal covered with mortar under a wet-dry cyclic condition were investigated to apply for the measurement of corrosion rates of reinforcing steel in concrete structure. The carbon steel in mortar having t=3 mm cover thickness was exposed to the alternate condition of 6 h immersion in chloride containing solution and 18 h drying at $25^{\circ}C$ and 50%RH. The electrochemical phenomena of a carbon steel and mortar interface was explained by an equivalent circuit consisting of a solution resistance, a charge transfer resistance and a CPE(Constant Phase Element). The corrosion rates were monitored continuously during exposure using an AC impedance technique. Simultaneously, the current distribution over the working electrode during impedance measurement was analyzed from the phase shift, $\theta$, in an intermediate frequency. The result showed that corrosion rate monitoring using an AC impedance method is suitable under the given exposure conditions even during the drying period when the metal is covered with the wetted mortar.