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Beta-divergence based two-phase segmentation model for synthetic aperture radar images
IET 2016 Electronics letters Vol.52 No.20
<P>A general two-phase segmentation model (beta-CCV) for synthetic aperture radar (SAR) images is introduced. The proposed model is based on the beta-divergence similarity measure and the convex-relaxed Chan-Vese model. The main advantage of beta-divergence with non-positive value of beta is that it is an expedient similarity measure for high dynamic range SAR images with strong scatterers. In addition, due to the global optimum property of beta-divergence, naturally merge the beta-divergence similarity measure into the convex-relaxed Chan-Vese model. Hence, we can find solutions of beta-CCV in a more stable way through convex optimisation. The proposed beta-CCV model shows overall better performance than the state-of-the-art segmentation method.</P>
Woo, H.,Lee, K.,Park, J.C.,Park, K.H. Elsevier 2016 SOLID STATE SCIENCES Vol.53 No.-
<P>A one-pot synthesis of rose-like Pd-Fe3O4 nanocomposites via the controlled thermal decomposition of Fe(CO)(5) and reduction of Pd(OAc)(2) is reported. This rose-like Pd-Fe3O4 composite structure has a high surface area owing to the individual Pd-Fe3O4 nanosheets, which imparted a high catalytic activity for Sonogashira coupling reactions. Moreover, the catalyst also demonstrated magnetic recyclability. (C) 2016 Elsevier Masson SAS. All rights reserved.</P>
Development of carbon-based cathodes for Li-air batteries: Present and future
Woo, H.,Kang, J.,Kim, J.,Kim, C.,Nam, S.,Park, B. Springer Science + Business Media 2016 ELECTRONIC MATERIALS LETTERS Vol.12 No.5
<P>Rechargeable lithium-air (Li-air) batteries are regarded as one of the most fascinating energy storage devices for use in the future electric vehicles, since Li-air batteries provide ten-times-higher theoretical capacities than those from current Li-ion batteries. Nonetheless, Li-air batteries have not yet been implemented to the market because of several major drawbacks such as low capacity, poor cycle life, and low round-trip efficiency. These battery performances are highly dependent on the design of air cathodes, thus much effort has been devoted to the development of high performance cathode. Among various materials, carbonaceous materials have been widely studied as the basis of air cathodes especially for non-aqueous Li-O-2 cells due to their high electric conductivity, low cost, and ease of fabrication. This review summarizes the history, scientific background, and perspectives of Li-air batteries, particularly from the viewpoint of carbon-based air cathodes.</P>
Recent developments in hybrid iron oxide-noble metal nanocatalysts for organic reactions
Woo, H.,Park, K.H. Elsevier Science Publishers 2016 CATALYSIS TODAY - Vol.278 No.2
<P>A review of recent developments in the synthesis of hybrid iron oxide-noble metal nanocomposites and their application to various organic reactions is presented herein. Focus is placed on various strategies for achieving (1) Au nanoparticles (NPs) on Fe3O4@polymer catalysts, (2) optimized dispersion and stability of Fe3O4/Pd catalysts, (3) Au NPs supported on Fe2O3-graphene oxide hybrid nanosheets and (4) roselike Pd-Fe3O4 hybrid nanocomposite-supported Au nanocatalysts. Further application of such hybrid nanocomposites as catalysts for various organic reactions is discussed in brief. (C) 2016 Elsevier B.V. All rights reserved.</P>
Woo, H.,Jo, H.,Kim, J.,Cho, S.,Jo, Y.,Roh, C.H.,Lee, J.H.,Seo, Y.,Park, J.,Kim, H.,Hahn, C.K.,Im, H. ELSEVIER 2017 CURRENT APPLIED PHYSICS Vol.17 No.8
<P>A high quality, single phase InGaN film is fabricated on a GaN/Si (111) substrate by optimizing the pulse patterned In supply with a plasma-assisted MBE technique. Compositional phase separation in InGaN is considerably suppressed. The optical and structural properties of the single phase InGaN epitaxial film are consistently confirmed by atomic force microscopy, X-ray diffraction and photoluminescence measurements. We propose a growth mechanism for single phase InGaN in terms of optimal incorporation and surface migration of In atoms. (C) 2017 Elsevier B.V. All rights reserved.</P>
Woo, H.,Lee, J.,Jo, Y.,Han, J.,Kim, J.,Kim, H.,Roh, C.H.,Lee, J.H.,Park, J.,Hahn, C.K.,Im, H. Elsevier 2015 CURRENT APPLIED PHYSICS Vol.15 No.9
We report on the effect of oxygen annealing for GaN surface on the Schottky barrier configuration and leakage current in Ni-AlGaN/GaN Schottky barrier diodes. After oxygen annealing, their turn-on voltage and reverse-bias leakage current characteristics are significantly improved due to a reduction in the Schottky barrier height (SBH) and suppression in the surface states respectively. Interface state density extracted from the Terman method was reduced by 2 orders of magnitude. X-ray photoelectron spectroscopy measurements show that the oxygen annealing induces Ga<SUB>2</SUB>O<SUB>3</SUB> on the GaN surface. The formation of Ga<SUB>2</SUB>O<SUB>3</SUB> reduces the interface state density as well as lowers the SBH through the modification of hybridized metal induced gap states.
Simultaneous analysis of 17 diuretics in dietary supplements by HPLC and LC-MS/MS
Woo, H.,Kim, J.W.,Han, K.M.,Lee, J.H.,Hwang, I.S.,Lee, J.H.,Kim, J.,Kweon, S.J.,Cho, S.,Chae, K.R.,Han, S.Y.,Kim, J. Informa UK (TaylorFrancis) 2013 Food additives & contaminants. Part A. Chemistry, Vol.30 No.2
<P>In order to test health foods for illegally added diuretics for weight loss, we developed simple, rapid, selective, and sensitive methods using HPLC and LC-MS/MS for the simultaneous analysis of 17 diuretics in dietary supplements. HPLC conditions were set with a Capcell-pak C18, using a mobile phase consisting of gradient conditions, UV detection at 254 nm and validated for linearity (r(2)> 0.999), precision (CV 3%), recoveries (90.4-102.8%) and reproducibility. Identification and quantification of 17 diuretics were accomplished by ion-spray LC-MS/MS using multiple reaction monitoring (MRM). The chromatographic separation was carried out under the reversed-phase mechanism on an HSS-T3 column. The LC-MS/MS method was validated for linearity (r(2)> 0.99) and precision (CV < 13%). Sixteen dietary supplements were tested with the developed methods. Diuretics were not detected in all samples. Extraction recovery was also investigated and the extraction recoveries in different formulations were from 88% to 110% and from 81% to 116% using HPLC and LC-MS/MS, respectively. There was no significant difference in recoveries in the type of dietary supplements. Based on this result, the developed methods to monitor illegal drug adulterations in dietary supplements using HPLC and LC-MS/MS are simple, fast and reliable. Therefore, it is applicable to routine drug-adulteration screening.</P>