Yoonmi Lee, Hyun Jae Song, Hyeon Suk Shin, Hyun Joon Shin, Hee Cheul Choi,
Discrete transition-metal nanoparticles are spontaneously formed on the sidewalls of single-walled carbon nanotubes (SWNTs), which are noncovalently functionalized with 2,2′;6,2′′-terpyridine (Terpy). Such nanotubes are electron-rich hybrid systems, which overcome the energy barrier that prohibits spontaneous electron transfer from SWNTs to transition-metal ions. Hence, the nucleation of transition-metal ions on the nanotube surfaces becomes energetically favorable at room temperature.
Tópico(s): Nanopore and Nanochannel Transport Studies
2005 - Wiley | Small
Hyung Mo Jeong, Jung Woo Lee, Weon Ho Shin, Yoon Jeong Choi, Hyun Joon Shin, Jeung Ku Kang, Jang Wook Choi,
Although various carbon nanomaterials including activated carbon, carbon nanotubes, and graphene have been successfully demonstrated for high-performance ultracapacitors, their capacitances need to be improved further for wider and more challenging applications. Herein, using nitrogen-doped graphene produced by a simple plasma process, we developed ultracapacitors whose capacitances (∼280 F/gelectrode) are about 4 times larger than those of pristine graphene based counterparts without sacrificing ...
Tópico(s): Advancements in Battery Materials
2011 - American Chemical Society | Nano Letters
Jaeku Park, Intae Eom, Tai‐Hee Kang, Seungyu Rah, Ki Hyun Nam, Jaehyun Park, Sangsoo Kim, Soonnam Kwon, Sang Han Park, Kyung Sook Kim, H.J. Hyun, Seung Nam Kim, Eun Hee Lee, Hocheol Shin, Seonghan Kim, Myong-jin Kim, Hyun‐Joon Shin, Docheon Ahn, Jun Lim, Chung-Jong Yu, Changyong Song, Hyunjung Kim, Do Young Noh, Heung Sik Kang, BongSoo Kim, Kwang-Woo Kim, In Soo Ko, Moo–Hyun Cho, Sunam Kim,
The Pohang Accelerator Laboratory X-ray Free Electron Laser project, a new worldwide-user facility to deliver ultrashort, laser-like x-ray photon pulses, will begin user operation in 2017 after one year of commissioning. Initially, it will provide two beamlines for hard and soft x-rays, respectively, and two experimental end-stations for the hard x-ray beamline will be constructed by the end of 2015. This article introduces one of the two hard x-ray end-stations, which is for hard x-ray pump-probe ...
Tópico(s): X-ray Spectroscopy and Fluorescence Analysis
2015 - Elsevier BV | Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
Hoyoung Jang, Hyeong‐Do Kim, Minseok Kim, Sang Han Park, Soonnam Kwon, Ju Yeop Lee, Sang‐Youn Park, Gisu Park, Seonghan Kim, H.J. Hyun, S. M. Hwang, Chae-Soon Lee, Chae-Yong Lim, Wonup Gang, Myeongjin Kim, Seongbeom Heo, Jin‐Hong Kim, Gigun Jung, Seung-Nam Kim, Jaeku Park, Jihwa Kim, Hocheol Shin, Jaehun Park, T. Y. Koo, Hyun‐Joon Shin, Hoon Heo, Changbum Kim, Changi-Ki Min, Jang-Hui Han, Heung-Sik Kang, Heung‐Soo Lee, Kyung Sook Kim, Intae Eom, Seungyu Rah,
Resonant elastic x-ray scattering has been widely employed for exploring complex electronic ordering phenomena, such as charge, spin, and orbital order, in particular, in strongly correlated electronic systems. In addition, recent developments in pump–probe x-ray scattering allow us to expand the investigation of the temporal dynamics of such orders. Here, we introduce a new time-resolved Resonant Soft X-ray Scattering (tr-RSXS) endstation developed at the Pohang Accelerator Laboratory X-ray Free ...
Tópico(s): Physics of Superconductivity and Magnetism
2020 - American Institute of Physics | Review of Scientific Instruments
Dongyoon Shin, Beomgyun Jeong, Bongjin Simon Mun, Hongrae Jeon, Hyun‐Joon Shin, Jaiyoon Baik, Jaeyoung Lee,
Nitrogen–carbon (N–C) species is a potential electrocatalyst for oxygen reduction reaction (ORR) in electrochemical energy conversion cells, but its mechanistic origin of ORR on the N–C surface is still unclear. We show our facile approach to the synthesis of highly active Co-modified N–C catalyst and investigated the origin of ORR activity of electrospun N–C species by removing the metal with hydroxide carbon etching and acid metal leaching. Through the detailed investigation on the origin of ORR ...
Tópico(s): Advanced battery technologies research
2013 - American Chemical Society | The Journal of Physical Chemistry C
J.‐S. Kang, S. S. Lee, G. Kim, Hongjoo J. Lee, H.K. Song, Y. J. Shin, Sang Wook Han, Chanyong Hwang, Min‐Cherl Jung, Hyun Joon Shin, B. H. Kim, S. K. Kwon, B. I. Min,
Electronic structures of delafossite oxides $\mathrm{Ag}{\mathrm{Ni}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}{\mathrm{O}}_{2}$ and the frustrated Jahn-Teller (JT) system $A\mathrm{Ni}{\mathrm{O}}_{2}$ $(A=\mathrm{Li},\mathrm{Na})$ have been investigated by employing soft x-ray absorption spectroscopy and photoemission spectroscopy (PES). It is found that Ni ions are in the ${\mathrm{Ni}}^{2+}\text{\ensuremath{-}}{\mathrm{Ni}}^{3+}$ mixed-valent states and that the low-spin (LS) ${\mathrm{Ni}}^{3+}$ component increases ...
Tópico(s): Advanced Condensed Matter Physics
2007 - American Physical Society | Physical Review B
Hyunseob Lim, Hyeon Suk Shin, Hyun‐Joon Shin, Hee Cheul Choi,
We developed a facile chemical route by which single-walled carbon nanotube (SWNT) Schottky diodes are realized. When a bias voltage was applied to a lithium ion intercalated SWNT field effect transistor (FET) device, lithium ions intercalated between 1-pyrenmethylamine (1-PMA), and SWNTs are migrated to the drain (−) electrode to be reduced at the junction of SWNT and drain metal electrode. As a result, asymmetric work function energy levels are formed between both junctions of SWNT−drain and SWNT−source, ...
Tópico(s): Molecular Junctions and Nanostructures
2008 - American Chemical Society | Journal of the American Chemical Society
Beomgyun Jeong, Dongyoon Shin, Hongrae Jeon, Joey D. Ocon, Bongjin Simon Mun, Jaeyoon Baik, Hyun‐Joon Shin, Jaeyoung Lee,
Abstract Platinum (Pt) is the best electrocatalyst for the oxygen reduction reaction (ORR) in hydrogen fuel cells, but it is an extremely expensive resource. The successful development of a cost‐effective non‐Pt ORR electrocatalyst will be a breakthrough for the commercialization of hydrogen‐air fuel cells. Ball milling has been used to incorporate metal and nitrogen precursors into micropores of carbon more effectively and in the direct nitrogen‐doping of carbon under highly pressurized nitrogen ...
Tópico(s): Advanced battery technologies research
2014 - Wiley | ChemSusChem
Hyeon Suk Shin, Hyun Chul Choi, Yeon-Wook Jung, Seung Bin Kim, Ha Jin Song, Hyun Joon Shin,
We have taken a systematic approach for interpreting X-ray photoemission spectroscopy data for passivated silver nanoparticles, and for the first time we have been able to determine the effects of nanoparticle size and of the nanoparticle stabilizers on the observed binding energies of Ag core electrons. The binding energy of Ag 3d5/2 core electrons was found to increase with decreasing nanoparticle size.
Tópico(s): Copper-based nanomaterials and applications
2003 - Elsevier BV | Chemical Physics Letters
Ji Hoon Yang, Dae Ho Lee, Min Hyung Yum, Yong Sook Shin, Eun‐Jung Kim, Chong-Yun Park, Myeung Hoi Kwon, Cheol‐Woong Yang, Ji‐Beom Yoo, Hajin Song, Hyun‐Joon Shin, Yong‐Wan Jin, Jong Min Kim,
Tópico(s): Semiconductor materials and devices
2006 - Elsevier BV | Carbon
Hyun‐Joon Shin, Sang‐Hum Kwon,
Abstract We have examined the barium ferrite powder X-ray diffraction patterns in the PDF using experimental and calculated diffractograms. An improved calculated diffractogram is proposed. The result indicates that the primary peak of barium ferrite is not (107) but is (114).
Tópico(s): Magnetic Properties and Synthesis of Ferrites
1992 - Cambridge University Press | Powder Diffraction
Won‐Sub Yoon, Kwang‐Bum Kim, Min Gyu Kim, Min-Kyu Lee, Hyun-Joon Shin, Jay-Min Lee, Jae‐Sung Lee, Chul-Hyun Yo,
To investigate the electronic structure of the electrochemically Li-ion deintercalated Li1-xCoO2 system, soft X-ray absorption spectroscopy (XAS) for the oxygen K-edge and the Co LII,III-edge has been carried out intensively with compositional x value variation, compared with Co K-edge X-ray absorption near edge structure (XANES) spectroscopy. To get reasonably good XAS spectra for the electrochemically Li-ion deintercalated Li1-xCoO2 system, we made a binder-free LiCoO2 film electrode using the electrostatic ...
Tópico(s): Electron and X-Ray Spectroscopy Techniques
2002 - American Chemical Society | The Journal of Physical Chemistry B
Hyun Chul Choi, Sang‐Yun Lee, Seung Bin Kim, Min Gyu Kim, Min Kyu Lee, Hyun Joon Shin, Jae Sung Lee,
Cobalt oxide is known to exhibit a large capacity as a negative electrode in lithium-ion batteries. Here, Co K-edge X-ray absorption spectroscopy (XAS) was used to investigate variations in the local structure during the first electrochemical cycle of the insertion−extraction of lithium into CoO. The XANES and EXAFS spectra in LiyCoO (y: lithium content) varied markedly with the lithium content. The initial insertion of lithium leads to the reduction of Co2+ in the pristine CoO to the reduced metallic ...
Tópico(s): Extraction and Separation Processes
2002 - American Chemical Society | The Journal of Physical Chemistry B
J. W. Kim, Han Woong Yeom, Yong‐Duck Chung, K. Jeong, C. N. Whang, M. K. Lee, Hyun Joon Shin,
Chemical bonding structures of nitrogen within very thin oxynitride films on Si(100) have been investigated by high-resolution photoemission spectroscopy using synchrotron radiation. The oxynitride films nitrided by the rapid thermal process with NO and ${\mathrm{N}}_{2}\mathrm{O}$ are systematically compared. Two distinct N $1s$ components are resolved for both films with a binding-energy difference of \ensuremath{\sim}0.61 eV, which are assigned to the N atoms at the interfaces and those in the ${\mathrm{ ...
Tópico(s): Electronic and Structural Properties of Oxides
2002 - American Physical Society | Physical review. B, Condensed matter
Yong-Hee Han, In-Hoon Choi, Ho-Kwan Kang, Jong‐Yeon Park, Kun-Tae Kim, Hyun‐Joon Shin, Sung Moon,
Vanadium oxide thin film is a promising material for uncooled microbolometers due to its high temperature coefficient of resistance (TCR) at room temperature. It is, however, very difficult to deposit vanadium oxide thin films having a high temperature coefficient of resistance and low resistance because of the process limits in microbolometer fabrication. We present a novel fabrication method for vanadium oxide thin films having good electrical properties. Through the formation of a sandwich structure ...
Tópico(s): Advanced Memory and Neural Computing
2003 - Elsevier BV | Thin Solid Films
Michael Gleicher, Hyun Joon Shin, Lucas Kovar, Andrew Jepsen,
No abstract available.
Tópico(s): Human Pose and Action Recognition
2003 - Association for Computing Machinery | ACM Transactions on Graphics
Sungdae Ji, Changyong Song, Jin Young Koo, K.-B. Lee, Yong Joon Park, J. Y. Kim, J.-H. Park, Hyun Joon Shin, Jong‐Soo Rhyee, B. H. Oh, B. K. Cho,
Resonant x-ray scattering experiments at the Gd L3 edge show interference between magnetic and anisotropic tensor susceptibility (ATS) reflections in GdB4. Energy profiles obtained from the magnetic and ATS resonances exhibited approximately 10 eV separation between the maximum resonance energies. The findings show that the Gd 5d band experienced hybridization giving rise to a significant split into isotropic lower energy band and distorted upper band states that account for the magnetic and ATS ...
Tópico(s): Boron and Carbon Nanomaterials Research
2003 - American Physical Society | Physical Review Letters
Chang Ouk Kim, Hyun Joon Shin,
Tópico(s): Distributed and Parallel Computing Systems
2003 - Springer Science+Business Media | The International Journal of Advanced Manufacturing Technology
Ranju Jung, Jae-Cheol Lee, Ye-Won So, Taewon Noh, S.-J. Oh, Jong‐Cheol Lee, Hyun‐Joon Shin,
We have investigated the electronic structure of transition-metal (TM=Sc, Y, Zr, and Nb)-doped Al2O3 by x-ray photoemission spectroscopy (XPS) and x-ray absorption spectroscopy (XAS). In valence bands of these TM-doped Al2O3 measured by XPS, the highest occupied levels and the shapes of valence bands are almost unchanged from the pure alumina. On the other hand, XAS spectra obtained at the oxygen K-edge show that Nb- and Zr-doped Al2O3 show localized d states in the bandgap below the conduction band ...
Tópico(s): Integrated Circuits and Semiconductor Failure Analysis
2003 - American Institute of Physics | Applied Physics Letters
Joo‐Yul Lee, Jae Woo Kim, Min‐Kyu Lee, Hyun‐Joon Shin, Hyuntae Kim, Su‐Moon Park,
Effects of organic additives such as benzoic acid (BA) and poly(ethylene glycols) (PEGs) on the initial stages of zinc electroplating were investigated at an iron electrode using cyclic voltammetry, energy-dispersive spectroscopy, soft X-ray absorption spectroscopy, and electrochemical impedance spectroscopy in an acidic zinc chloride solution. BA mainly contributed to the roughness control of the zinc layer with a relatively weak interaction with zinc ions. However, PEG molecules raise the overpotential ...
Tópico(s): Electrocatalysts for Energy Conversion
2003 - Institute of Physics | Journal of The Electrochemical Society
Eun Seong Lee, Hyun Joon Shin, Kun Na, You Han Bae,
Poly(L-histidine)-poly(ethylene glycol) diblock copolymers (polyHis-b-PEG) were prepared and used for the construction of polymeric micelles responding to local pH changes in the body. PolyHis was synthesized by ring opening polymerization of L-histidine N-carboxyanhydride, the imidazole amine group of which was protected by the dinitrophenyl group. The resulting polymer (M(n): 5,000 g/mole) was coupled to poly(ethylene glycol) (M(n): 2,000 g/mole) via an amide linkage using the dicyclohexyl carbodiimide ...
Tópico(s): Polymer Surface Interaction Studies
2003 - Elsevier BV | Journal of Controlled Release
Hyun‐Joon Shin, Dong-Eon Kim, Tong-Nyong Lee,
Soft-x-ray amplification in the C vi Balmer \ensuremath{\alpha} transition is observed in a capillary discharge. The capillary is made of polyethylene with a bore diameter of 1.2 mm. A hot and dense carbon plasma which is formed on the capillary axis region expands radially and collides with the wall where it undergoes a rapid cooling and subsequent recombination. The amplification takes place in this cool (${\mathit{T}}_{\mathit{e}}$\ensuremath{\sim}13 eV) plasma region, according to space-resolved ...
Tópico(s): Plasma Diagnostics and Applications
1994 - American Physical Society | Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics
D. H. Kim, H. J. Lee, G. Kim, Y. S. Koo, Jong Hoon Jung, Hyun Joon Shin, J.-Y. Kim, J.-S. Kang,
The electronic structures of ${\text{BaTiO}}_{3}@X$ (core@shell) nanoparticles ($X=\ensuremath{\gamma}{\text{-Fe}}_{2}{\text{O}}_{3}$, ${\text{Fe}}_{3}{\text{O}}_{4}$, and Fe) have been investigated by employing soft x-ray-absorption spectroscopy and x-ray magnetic circular dichroism (XMCD). It is found that the valence states of Ti ions near interfaces are formally tetravalent $({\text{Ti}}^{4+}:3{d}^{0})$ and that the valence states of Fe ions in shells are essentially the same as those of the corresponding ...
Tópico(s): Magnetic Properties and Synthesis of Ferrites
2009 - American Physical Society | Physical Review B
Shanshan Li, Hyun Joon Shin, Eric L. Ding, Rob M. van Dam,
The association of obesity with development of type 2 diabetes may be partly mediated by altered secretion of adipokines by adipose tissue. Greater adiposity down-regulates secretion of adiponectin, an adipokine with anti-inflammatory and insulin-sensitizing properties. The strength and consistency of the relation between plasma adiponectin and risk of type 2 diabetes is unclear.To systematically review prospective studies of the association of plasma adiponectin levels and risk of type 2 diabetes. ...
Tópico(s): Biomarkers in Disease Mechanisms
2009 - American Medical Association | JAMA
Jieun Lee, Bongjae Kim, B. H. Kim, B. I. Min, S. Koleśnik, O. Chmaissem, J. Mais, B. Dąbrowski, Hyun Joon Shin, D. H. Kim, Hongjoo J. Lee, J.‐S. Kang,
The electronic structures of perovskite ${\text{SrMn}}_{1\ensuremath{-}x}{\text{Mo}}_{x}{\text{O}}_{3}$ $(0\ensuremath{\le}x\ensuremath{\le}0.5)$ have been investigated by employing soft x-ray absorption spectroscopy (XAS). $\text{Mn}\text{ }2p$ XAS shows the systematic change in the valence states of Mn ions in ${\text{SrMn}}_{1\ensuremath{-}x}{\text{Mo}}_{x}{\text{O}}_{3}$ due to the substitution of hexavalent ${\text{Mo}}^{6+}(4{d}^{0})$ ions. With increasing $x$, the valence states and the spin configurations ...
Tópico(s): Multiferroics and related materials
2009 - American Physical Society | Physical Review B
Mikel Sadek, Neal S. Cayne, Hyun Joon Shin, Irene C. Turnbull, Michael L. Marin, Peter L. Faries,
Introduction Prior neck irradiation may induce atherosclerosis in the carotid artery and is considered an indication for carotid angioplasty and stenting (CAS). This study sought to evaluate the effect of neck radiation therapy (XRT) on the rate of restenosis and embolic potential in patients undergoing CAS. Methods Two hundred ten CAS procedures were performed on 193 patients (XRT [N = 28], non-XRT [N = 182]). Mean follow-up was 347 ± 339 days (median, 305 days; range, 16-1354 days). Duplex velocity criteria for restenosis ...
Tópico(s): Cardiovascular Health and Disease Prevention
2009 - Elsevier BV | Journal of Vascular Surgery
Jinhee Kim, Ho-Kyun Lee, Jinwook Chung, Hyun Joon Shin, Hu Jong Lee, Ja Kang Ku,
We have investigated the dissipation characteristics in the mixed state of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ film, grown epitaxially on the ${\mathrm{SrTiO}}_{3}$(100) substrate, in terms of external transport current as well as magnetic field applied parallel to the c axis of the film. The dissipation fits well the thermally activated flux creep model, R=${\mathit{R}}_{0}$ exp(-U/${\mathit{k}}_{\mathit{B}}$T), where U is a function ...
Tópico(s): Magnetic and transport properties of perovskites and related materials
1991 - American Physical Society | Physical review. B, Condensed matter
The development of a scheduling methodology for a parallel machine problem with rework processes is presented in this paper. The problem is to make a schedule for parallel machines with rework probabilities, due-dates, and sequence dependent setup times. Two heuristics are developed based on a dispatching algorithm and problem-space-based search method. In order to evaluate the efficacy of the proposed algorithms, six performance indicators are considered: total tardiness, maximum lateness, mean ...
Tópico(s): Optimization and Packing Problems
2008 - Taylor & Francis | International Journal of Production Research
Zhimei Sun, Jian Zhou, Hyun‐Joon Shin, Andreas Blomqvist, Rajeev Ahuja,
Nitrogen doping is identified to be a sufficient way to reduce the power consumption of Ge2Sb2Te5, a phase-change material for data storage. On the basis of ab initio molecular dynamics simulations, we show that the doped N in amorphous Ge2Sb2Te5 coexist as Ge(Sb, Te)N complex and N2, and high density of the film produces more N2. Furthermore, both Ge(Sb, Te)N complex and N2 are stable upon annealing at 600 K.
Tópico(s): Chalcogenide Semiconductor Thin Films
2008 - American Institute of Physics | Applied Physics Letters
Yong Jae Cho, Changhyun Kim, Han Sung Kim, Jeunghee Park, Hyun Chul Choi, Hyun‐Joon Shin, Guohua Gao, Hong Seok Kang,
Silicon (Si)-doped multiwalled boron nitride nanotubes (BNNTs) were synthesized via thermal chemical vapor deposition. Electron energy-loss spectroscopy revealed that 5% of Si atoms were homogeneously doped into the BNNTs. X-ray absorption and photoelectron spectroscopy measurements demonstrated that the Si−B and Si−N bonding structures are produced, where both structures reduce the π bonding states of the BN sheets. The valence band analysis indicates that the Si doping decreases the band gap by ...
Tópico(s): MXene and MAX Phase Materials
2008 - American Chemical Society | Chemistry of Materials