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Bucheon, South Korea

The Catholic University of Korea is a private Roman Catholic institution of higher education in South Korea. It operates campuses in Seoul and in the neighboring Bucheon City. The university's medical school, considered as one of the most prestigious in South Korea, has eight affiliated hospitals in major cities of the country. The university has been consistently ranked as one of the premier universities in South Korea and has been regarded in both national and international university rankings. Wikipedia.

Wee J.-H.,Catholic University of Korea
Applied Energy | Year: 2011

Molten carbonate fuel cell (MCFC)/gas turbine (GT) hybrid system has attracted a great deal of research effort due to its higher electricity efficiency. However, its technology has remained at the conceptual level due to incomplete examination of the related issues, challenges and variables. To contribute to the development of system technology, the MCFC/GT hybrid system is analyzed and discussed herein. A qualitative comparison of the two kinds of MCFC/GT hybrid system, indirect and direct, is hindered by the many variables involved. However, the indirect system may be preferred for relatively small-scale systems with the micro-GT. The direct system can be more competitive in terms of system efficiency and GT selection due to the optionality of system layouts as well as even higher GT inlet temperature. System layout is an important factor influencing the system efficiency. The other issues such as GT selection, system pressurization and part-load operation are also significant. © 2011 Elsevier Ltd.

An B.-K.,Catholic University of Korea | Gierschner J.,IMDEA Madrid Institute for Advanced Studies | Park S.Y.,Seoul National University
Accounts of Chemical Research | Year: 2012

π-Conjugated organic molecules represent an attractive platform for the design and fabrication of a wide range of nano- and microstructures for use in organic optoelectronics. The desirable optical and electrical properties of π-conjugated molecules for these applications depend on their primary molecular structure and their intermolecular interactions such as molecular packing or ordering in the condensed states. Because of the difficulty in satisfying these rigorous structural requirements for photoluminescence and charge transport, the development of novel high-performance π-conjugated systems for nano-optoelectronics has remained a challenge.This Account describes our recent discovery of a novel class of self-assembling π-conjugated organic molecules with a built-in molecular elastic twist. These molecules consist of a cyano-substituted stilbenic π-conjugated backbone and various terminal functional groups, and they offer excellent optical, electrical, and self-assembly properties for use in various nano-optoelectronic devices. The characteristic "twist elasticity" behavior of these molecules occurs in response to molecular interactions. These large torsional or conformational changes in the cyanostilbene backbone play an important role in achieving favorable intermolecular interactions that lead to both high photoluminescence and good charge carrier mobility in self-assembled nanostructures.Conventional π-conjugated molecules in the solid state typically show concentration (aggregation) fluorescence quenching. Initially, we describe the unique photoluminescence properties, aggregation-induced enhanced emission (AIEE), of these new cyanostilbene derivatives that elegantly circumvent these problems. These elastic twist π-conjugated backbones serve as versatile scaffolds for the preparation of well-defined patterned nanosized architectures through facile self-assembly processes. We discuss in particular detail the preparation of 1D nanowire structures through programmed self-assembly.This Account describes the importance of utilizing AIEE effects to explore optical device applications, such as organic semiconducting lasers (OSLs), optical memory, and sensors. We demonstrate the rich electronic properties, including the electrical conductivity, field-effect carrier mobility, and electroluminescence of highly crystalline 1D nanowire and coaxial donor-acceptor nanocable structures composed of elastic twist π-conjugated molecules. The electronic properties were measured using various techniques, including current-voltage (I-V), conducting-probe atomic force microscopy (CP-AFM), and space-charge-limited- current (SCLC) measurements. We prepared and characterized several electronic device structures, including organic field-effect transistors (OFETs) and organic light-emitting field-effect transistors (OLETs). © 2011 American Chemical Society.

Wee J.-H.,Catholic University of Korea
Applied Energy | Year: 2013

This work reviews the availability and the potential of the carbon capture and storage (CCS) technology using coal fly ash (FA). Because the technology can be effectively applied on-site to coal fired power plants and as FA contains sufficient alkali components, the technology may be another option of CCS technology to a limited extent. The technology can be divided into wet and dry processes. In the former, the available components for CCS in FA are leached into solution by the solvent where they are subsequently consumed for carbonation to store CO2. Particularly, the CO2 storage capacity of CaO-enriched FA solution mixed with brine under high pressure may be equal to or greater than the true CO2 emission reduction achieved by applying FA as a cement additive. In the dry process, FA can be used as a direct support or as the raw material of the sorbent supports for CO2 capture. The dry process is effectively applied for CO2 capture rather than storage because the sorbents should be regenerated. Another advantage of the technology is the stabilization of the harmful components present in FA, which are mostly co-precipitated with carbonated FA during the process. © 2013 Elsevier Ltd.

Wee J.-H.,Catholic University of Korea
Renewable and Sustainable Energy Reviews | Year: 2010

Fuel cells (FCs) and their hybrid systems can play a key role in reducing carbon dioxide (CO2) emissions. The present paper analyzes the contributions of the FC system to CO2 emission reduction in three application fields. In the mobile application field, the direct methanol FC system has little or no influence on CO2 emission reduction. The benefit of the FC in CO2 emission reduction in the transportation field is directly dependant on the H2 production method. Pre-combustion technology (with carbon capture) represents one of the best mid-term solutions for H2 production. If FC vehicles (FCVs) use the H2 produced by this process, the CO2 emissions in this field could be decreased to 70-80% of the traditional CO2 emissions. In the stationary application field, the FC system can be effectively operated as the distributed generation (DG) in terms of CO2 emission reduction. Among the various types of FC or FC hybrid system used for DG, the solid oxide FC (SOFC) hybrid system with a CO2 capture unit is the best option as it doubled the electricity efficiency compared to the traditional combustion cycle and decreases the CO2 emission to 13.4% of the traditional CO2 emission. However, the FC and carbon capture and sequestration (CCS) technologies need to be fully developed before the FC can contribute to reducing CO2 emissions. © 2009 Elsevier Ltd. All rights reserved.

Wee J.-H.,Catholic University of Korea
Renewable and Sustainable Energy Reviews | Year: 2014

The contribution of the molten carbonate fuel cell system (MCFCs) to carbon dioxide (CO2) emission reduction in power application is analyzed. MCFCs can separate and concentrate CO2 emitted from traditional thermal power plants (PPs) without reducing the plant's overall energy efficiency. MCFCs can also be used by itself as an effective CO2 separator or concentrator by managing the anode gas stream to increase the heat utilization of the system. The CO2 separated and concentrated by MCFCs is most effectively captured by condensation. MCFCs is currently used as a CO2 separator only to a limited extent due to its high cost and relatively small scale operation. However, MCFCs will substantially contribute to reduce CO2 emissions in power generation applications in the near future. © 2014 Elsevier Ltd.

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