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Kim, Doyeon,Lee, Geumbee,Kim, Daeil,Yun, Junyeong,Lee, Sang-Soo,Ha, Jeong Sook The Royal Society of Chemistry 2016 Nanoscale Vol.8 No.34
<P>In this study, we report the fabrication of a high performance flexible micro-supercapacitor (MSC) with an organic gel electrolyte containing a redox-active additive, referred to as poly(methyl methacrylate)-propylene carbonate-lithium perchlorate-hydroquinone (PMMA-PC-LiClO4-HQ). Hexagonal MSCs fabricated on thin polyethylene terephthalate (PET) films had interdigitated electrodes made of spray-coated multi-walled carbon nanotubes (MWNTs) on Au. The addition of HQ as a redox-active additive enhanced not only the specific capacitance but also the energy density of the MSCs dramatically, which is approximately 35 times higher than that of MSCs without the HQ additive. In addition, both areal capacitance and areal energy density could be doubled by fabrication of double-sided MSCs, where two MSCs are connected in parallel. The double-sided MSCs exhibited stable electrochemical performance during repeated deformation by bending. By dry-transferring the double-sided MSCs based on PMMA-PC-LiClO4-HQ on a deformable polymer substrate, we fabricated a stretchable MSC array, which also retained its electrochemical performance during a uniaxial strain of 40%. Furthermore, a wearable energy storage bracelet made of such an MSC array could operate a mu-LED on the wrist.</P>
Kim, Jisu,Kim, Bongkyu,An, Junyeong,Lee, Yoo Seok,Chang, In Seop Elsevier 2016 Bioresource technology Vol.213 No.-
<P><B>Abstract</B></P> <P>To prevent the occurrence of the organic crossover in membraneless microbial fuel cells (ML-MFCs), dual-anode MFC (DA-MFC) was designed from multi-anode concept to ensure anode zone. The anode zone addressed increase the utilization of organic matter in ML-MFCs, as the result, the organic crossover was prevented and performance of MFCs were enhanced. The maximum power of the DA-MFC was 0.46mW, which is about 1.56 times higher than the ML-MFC (0.29mW). Furthermore, the DA-MFC had advantage in correlation of organic substance concentration and dissolved oxygen concentration, and even electric over-potential. In addition, in terms of cathode fouling, the DA-MFC showed clearer surface. Hence, the anode zone should be considered in the advanced ML-MFC for practically use in wastewater treatment process, and also for scale–up of MFCs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ML-MFCs suffer from organic crossover to the cathode. </LI> <LI> The development of an anode zone using a dual-anode system was demonstrated. </LI> <LI> ML-MFC studies should consider anode zone characterizations. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Adsorption/desorption behavior of carbonyl sulfide gas on Scheelite type MWO<sub>4</sub> adsorbent
Kim, Junyeong,Do, Jeong Yeon,Park, No-Kuk,Hong, Jin-Pyo,Kang, Misook Elsevier 2018 Separation and purification technology Vol.207 No.-
<P><B>Abstract</B></P> <P>This study focused the metal oxide adsorbents to remove small amounts of carbonyl sulfide (OCS) during coal gasification, which was a preliminary step for Integrated Gasification Fuel Cell operation. This study attempted to improve the function of the adsorbent by introducing two kinds of metal species, alkaline earth metals (M=Ca, Mg, Sr, and Ba) and W, fabricated as a Scheelite-typed MWO<SUB>4</SUB> crystal. COS gases were broken down into CO and S segments on the surface of the adsorbents, and were then adsorbed onto the alkaline and W sides. The COS removals decreased in the order of CaWO<SUB>4</SUB> > SrWO<SUB>4</SUB> > BaWO<SUB>4</SUB> > MgWO<SUB>4</SUB> > WO<SUB>3</SUB>. When the adsorbent had an ideal basicity, the CO and S adsorbed well on the surface of the adsorbent, resulting in easy breakage of the CO and S bonds. But, this study indicated that it was more influential to optimally align the adsorbate and adsorbent surface. For the Scheelite-type CaWO<SUB>4</SUB> adsorbent, the distance of the adsorbing active site, CaOW, was similar in size to the COS adsorbate molecule, suggested a good alignment approaching the <I>C</I>-axis of the adsorbent. Moreover, an important result in this study determined by mass spectroscopy was that when COS adsorption was saturated on the MWO<SUB>4</SUB> surface, the adsorbed COS gases could desorb from the MWO<SUB>4</SUB> surface with CO<SUB>2</SUB>, SO<SUB>2</SUB>, CS, and CS<SUB>2</SUB> gases, which are more toxic than COS. This can be considered to other secondary environmental pollutants.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Scheelite-typed MWO<SUB>4</SUB> crystals fabricated by alkaline earth metals and W. </LI> <LI> COS molecules were broken down into CO and S segments on adsorbents. </LI> <LI> COS removal ability was the best on CaWO<SUB>4</SUB> adsorbent. </LI> <LI> On CaWO<SUB>4</SUB>, the COS adsorbate had a good alignment approaches forward the <I>C</I>-axis of the adsorbent. </LI> <LI> COS gases were desorbed as CO<SUB>2</SUB>, SO<SUB>2</SUB>, CS, and CS<SUB>2</SUB> gases. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Kim, Daehee,An, Junyeong,Kim, Bongkyu,Jang, Jae Kyung,Kim, Byung Hong,Chang, In Seop Wiley-VCH 2012 CHEM SUS CHEM Vol.5 No.6
<P>To scale-up microbial fuel cells (MFCs), installing multiple unit cells in a common reactor has been proposed; however, there has been a serious potential drop when connecting unit cells in series. To determine the source of the loss, a basic stack-MFC (BS-MFC) has been devised, and the results show that the phenomenon is due to ions on the anode electrode traveling through the electrolyte to be reduced at the cathode connected in series. As calculated by means of the percentage potential drop, the degree of potential drop decreased with an increase in the unit-cell distance. When the distance was increased from 1 to 8 cm, the percentage potential drop in BS-MFC1 decreased from 46.76 ± 0.90 to 45.08 ± 0.70 % and in BS-MFC2 from 46.41 ± 0.95 to 43.82 ± 2.23 %. As the p-value of the t-test was lower than 0.05, the difference was considered significant; however, if the unit cells are installed far enough from each other to avoid the potential drop phenomenon, the system will be less dense, consequently reducing the ratio of electrode area per volume of anode compartment and decreasing the power density of the system. Finally, this study suggests design criteria for scaling-up MFC systems: Multiple-electrode-installed MFCs are modularized, and the unit cells are connected in series across the module (connecting each unit cell does not share the anolyte).</P>
Junyeong Kim,Kug-Hwan Kim,Dongil Kwon 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.2
Since materials used in or exposed to high-temperature environments can undergo variation or degradation of mechanical properties, it is important to evaluate mechanical properties at high temperature, in particular for structural applications and aerospace materials. Instrumented indentation testing (IIT) is widely used to evaluate such mechanical properties of materials as tensile properties, residual stress, fracture toughness, etc., exploiting theoretical approaches to indentation mechanics. In this study, we used IIT to evaluate variations in tensile properties with temperature of the Ti alloy Ti-6Al-4V, a candidate material for aerospace applications, using a high-temperature chamber and a modified representation method. Comparison of our results with conventional uniaxial tensile test results showed good agreement (within a 10% error range) in yield strength and ultimate tensile strength. This confirms the potential of IIT for evaluating to evaluate high-temperature tensile properties of metallic materials and for research on material behavior in various temperature conditions.
A case of congenital non-neural granular cell tumor mimicking nevus lipomatosus superficialis
( Junyeong Park ),( Jiyun Jung ),( Eunbyul Cho ),( Eunjoo Park ),( Kwangho Kim ),( Kwangjoong Kim ) 대한피부과학회 2016 대한피부과학회 학술발표대회집 Vol.68 No.1
A 4-month-old infant presented with asymptomatic soft nodules on his right forearm, which had developed since birth and grown gradually. On the suspicion of nevus lipomatosus superficialis, biopsy was performed. Histopathologic findings showed monomorphic polygonal cells with abundant granular cytoplasm. Immunohistochemical stains for CD68 and vimentin were strongly positive, but were negative for S-100 protein. Based on the pathologic findings, the patient was finally diagnosed as non-neural granular cell tumor. Granular cell tumor (GCT) is benign, indolent and slow growing tumor which can be divided into conventional and non-neural GCT by immunoreactivity for S-100 protein. Non-neural granular cell tumor (NN-GCT) is typically manifested as a well-circumscribed, papulo-nodular dermal mass, and is known to occur in a younger group than does in conventional GCT, but is rare among children. To our knowledge, there have been no case reports of NN-GCT which appeared at birth and presented as grouped nodules as seen in this case. Therefore, we herein report this interesting case of congenital NN-GCT clinically mimicking NLS.