• Journal of the Korean Ceramic Society
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• v.52 no.1
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• pp.1-8
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• 2015

Thermoelectric (TE) technology is becoming increasingly important in applications of solid-state cooling and renewable energy sources. $Bi_2Te_3$-based TE materials are widely used in small-scale cooling and temperature control applications; however, higher levels of TE performance are required for new applications such as large-scale cooling (e.g., domestic refrigerators or air conditioners) and for highly efficient power generation system. Recently, the TE performance of $Bi_2Te_3$-based materials has been remarkably enhanced by the introduction of nanostructuring technologies which can be used to prepare TE raw materials. Because it takes into account the theoretical and experimental characteristics, nanostructuring has been shown to be one of the most promising ways to realize the simultaneous control of the electronic and thermal transport properties. In this review, emphasis is placed on bulk-type nanostructured $Bi_2Te_3$-based TE materials. Nanostructuring technologies for enhanced TE performance are summarized, and a few important strategies are presented.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.825-827
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• 2012

In this study, the variation in surface morphology of copper phthalocyanine (CuPc) thin films treated with a flow of acetone vapor assisted by nitrogen carrier gas was investigated. The CuPc nanorods with similar dimensions were well dispersed throughout the whole film surfaces after ~20 min. of treatment. However, the electronic absorption spectra only changed slightly, which indicates that molecular stacking was not altered during treatment. This treating method is simple and more advantageous compared to other solvent treating technologies such as mixed solvent spray treatment using organic solvents and water since it requires relatively mild treating conditions and does not need the presence of water.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.295-295
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• 2013

Supercapacitors with higher energy and power density are attracting growing attention for their wide range of potential applications such as portable electronic equipments, hybrid vehicle and cellular devices. In various classes of materials for supercapacitors, the redox pseudocapacitive materials such as conducting polymers and metal oxides have been most widely studied recently. The nanostructuring of the electrode surface has also been focused on since it can provide large surface area and consequently easy diffusion of ions in the capacitors. Among the active materials, in this work, we have used polyaniline (PANi) and manganese oxide ($MnO_2$). PANi is one of the promising electrode and active materials due to its desirable properties such as high electrochemical activity, high doping level and stability. $MnO_2$ is also widely studied material for supercapacitors since it is relatively cheap and environmentally friendly. In this work, we fabricated PANi hollow nanospheres by polymerizing aniline monomers on the polystyrene (PS) nanospheres and then dissolving the inner PS spheres. This nanostructuring of the PANi surface can provide large surface area and hence easy diffusion of electrolyte ions. We also incorporated $MnO_2$ nanoparticles into the PANi hollow nanospheres and investigated its electrochemical properties. It is expected that the combination of these two active materials with slightly different working potential windows show synergetic effects such as broader working potential range and enhanced specific capacitance.

• Applied Science and Convergence Technology
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• v.23 no.2
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• pp.72-82
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• 2014

Lithium-ion batteries (LIBs) have become popular electrochemical devices. Due to the unique advantages of LIBs in terms of high operating voltage, high energy density, low self-discharge, and absence of memory effects, their application range, which was primarily restricted to portable electronic devices, is now being extended to high-power applications, such as electric vehicles (EVs) and hybrid electrical vehicles (HEVs). Among various anode materials, $Li_4Ti_5O_{12}$ (LTO) is believed to be a promising anode material for high-power LIBs due to its advantages of high working potential and outstanding cyclic stability. However, the rate performance of LTO is limited by its intrinsically low electronic conductivity and poor $Li^+$ ion diffusion coefficient. This review highlights the recent progress in improving the rate performance of LTO through doping, compositing, and nanostructuring strategies.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.220-220
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• 2012

The supercapacitors with extraordinarily high capability for energy storage are attracting growing attention for their potential applications in portable electronic equipments, hybrid vehicles, cellular devices, and so on. The nanostructuring of the electrode surface can provide large surface area and consequently easy diffusion of ions in the capacitors. In addition, compared to two-dimensional nanostructures, the three-dimensional (3D) nano-architecture is expected to lead to significant enhancement of mechanical and electrical properties such as capacitance per unit area of the electrode. Polyaniline (PANi) is known as promising electrode material for supercapacitors due to its desirable properties such as high electro activity, high doping level and environmental stability. In this context, we fabricated well-ordered 3D PANi nanostructures on 3D polystyrene (PS) nanospheres which was arrayed by layer-by-layer stacking method. The height of the PANi nanostructures could be controlled by the number of PS layers stacked. 3D PANi hollow nanospheres were also fabricated by dissolving inner PS nanospheres, which resulted in further enhancement of the surface area and capacitance of the electrode.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.402.2-402.2
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• 2016

In photoelectrochemical (PEC) water splitting, Cu2ZnSnS4 (CZTS) compound has attracted intense attention as a photocathode due to not only large optical absorption coefficient, but also earth-abundance of constituent elements and suitable band alignment. With rapid development of nanotechnology, one-dimensional nanostructures of CZTS have been investigated as a potential form to achieve high efficiency because the nanostructures are expected to be capable of capturing more light and enhancing charge separation and transport. Here, we report a well-controlled fabrication route for vertically-aligned CZTS nanorod arrays on anodic aluminium oxide (AAO) template via simple sol-gel process followed by deposition of ZnS or CdS buffer layers on the CZTS nanorod to enhance charge separation. The structure, morphology, composition, optical absorption, and PEC properties of the resulting CZTS nanorod samples were characterized using X-ray diffraction, Raman spectroscopy, transmission electron microscopy, energy dispersive X-ray spectrometry, scanning electron microscopy, and UV-vis spectroscopy.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.74-75
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• 2006

In organic opto-electronic applications, such as light emitting diodes (LEDs) and photovoltaic devices (PVDs), the morphology of the active layer is of crucial importance. To control the morphology of the active layer the self-assembling properties of block copolymers was used. Several rod-coil semiconducting diblock copolymers consisting of a conjugated block and a second coil block functionalized with electron transporting and/or accepting materials (such as $C_{60}$) were synthesized. The conjugated block acting as light absorbing, electron donating and hole transporting material. The donor/acceptor photovoltaic devices performance with active layer the above mentioned semiconducting block copolymers will be presented.

• Ceramist
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• v.22 no.3
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• pp.230-242
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• 2019

Functional ceramics are widely utilized in a variety of application fields such as structural materials, sensors, energy devices, purification filter and etc due to their high strength, stability and chemical activity. With the breakthrough development of nanotechnology, many researchers have studied new types of nanomaterials including nanoparticle, nanorod, nanowire and nanoplate to realize high-performance ceramics. Especially several groups have focused on the 3D nanostructured ceramics because of their large surface area, efficient load transfer, ultra-fast ion diffusion and superior electrical (or thermal) conductivity. In this review, we introduce the reported fabrication strategies of the 3D nanostructured and functional ceramics, also summarized the 3D nanostructured ceramic based high-performance applications containing photocatalysts, structural materials, energy harvesting and storage devices.

• Journal of Powder Materials
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• v.23 no.2
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• pp.170-176
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• 2016

Lithium-ion batteries (LIBs) are rapidly improving in capacity and life cycle characteristics to meet the requirements of a wide range of applications, such as portable electronics, electric vehicles, and micro- or nanoelectro-mechanical systems. Recently, atomic layer deposition (ALD), one of the vapor deposition methods, has been explored to expand the capability of LIBs by producing near-atomically flat and uniform coatings on the shell of nanostructured electrodes and membranes for conventional LIBs. In this paper, we introduce various ALD coatings on the anode, cathode, and separator materials to protect them and improve their electrochemical and thermomechanical stability. In addition, we discuss the effects of ALD coatings on the three-dimensional structuring and conduction layer through activation of electrochemical reactions and facilitation of fluent charge collection.

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.39.2-40
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• 2008