Sang Woo Kim

Pohang University of Science and Technology, Geijitsu, North Gyeongsang, South Korea

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Publications (272)508.77 Total impact

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    ABSTRACT: We report the fabrication of nickel nanofiber catalysts supported on nickel metallic foam using a modified electrospinning with a grounded rotor and sequential reduction process. The robust deposition of aligned Ni nanofibers with a uniform morphology on the highly porous surfaces of the metallic foam could be achieved by controlling electrospinning parameters such as applied voltage, tip-collector-distance (TCD), concentration of polymer, and humidity. The diameters of the obtained nanofibers decreased with increasing voltage and TCDs. The uniform and thinnest Ni nanofibers on the Ni foam were obtained at a humidity of less than 30%, 15 kV applied voltage, and 17 cm TCD when using a precursor composed of nickel nitrate salt and poly(vinyl) pyrrolidone. The Ni foam catalyst support exhibited the superior thermal conducting property than other supports of MgO–MgAl2O4, Al2 O3, and SiC, enabling to a higher heat transfer during catalytic reaction. As a result, the Ni nanofiber catalyst with a high surface area and superior heat transfer performance, which is supported on the metallic foam, were successfully fabricated via a modified electrospinning for potential application of XTL process converting anything to liquids, such as for Gas-to-Liquid (GTL), Coal-to-Liquid (CTL), and Biomass-to-Liquid (BTL).
    Journal of Nanoscience and Nanotechnology 07/2015; 15(7). · 1.34 Impact Factor
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    ABSTRACT: A new minimization criterion for the normalized subband adaptive filter (NSAF), which is called improved NSAF (INSAF), was introduced recently to improve the performance of the steady-state mean-square deviation (MSD). However, the steady-state MSD analysis of the INSAF was not studied. Therefore, this paper proposes a general solution of steady-sate MSD analysis of the INSAF algorithm, which is based on the substitution of the past weight error vector in the weight error vector. The simulation shows that our theoretical results correspond closely with the computer simulation results in various environments.
    Signal Processing 01/2015; 106:49–54. · 2.24 Impact Factor
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    ABSTRACT: A series of Cu–ZnO–Al2O3 catalysts were prepared by coprecipitation method. The pH of solution was adjusted from 6 to 8 by using Na2CO3 solution. The prepared catalysts were evaluated for methanol synthesis from syngas (H2, CO and CO2) at lower temperature and pressures. Catalysts have been characterized by N2 physisorption, porosity measurements, XRD, TG/DTA, TPD (CO2/NH3) and XPS. Among all the catalysts pH 7 catalyst was shown higher catalytic activity towards methanol formation. It was found that the catalyst is mainly possessed the higher number of surface active sites (Cu0/Cu+), acidic and basic nature and optimum synergism between three components (Cu–ZnO–Al2O3). The activity results were evaluated with and without CO2 in syngas and it was found that higher CO conversion and higher methanol selectivity in the presence CO2.
    Journal of Nanoscience and Nanotechnology 01/2015; 15(1). · 1.34 Impact Factor
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    ABSTRACT: To overcome the performance degradation of least mean square (LMS)-type algorithms when input signals are correlated, the normalized subband adaptive filter (NSAF) was developed. In the NSAF, the regularization parameter influences the stability and performance. In addition, there is a trade-off between convergence rate and steady-state mean square deviation (MSD) according to the change of the parameter. Therefore, to achieve both fast convergence rate and low steady-state MSD, the parameter should be varied. In this paper, a variable regularization scheme for the NSAF is derived on the basis of the orthogonality between the weight-error vector and weight vector update, and by using the calculated MSD. The performance of the variable regularization algorithm is evaluated in terms of MSD. Our simulation results exhibit fast convergence and low steady-state MSD when using the proposed algorithm.
    Signal Processing 11/2014; 104:432–436. · 2.24 Impact Factor
  • Advanced Functional Materials 11/2014; 24(44). · 10.44 Impact Factor
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    Ik Chan Jeon, Sang Woo Kim, Young Jin Jung
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    ABSTRACT: The causes of sciatica are variable and include musculoskeletal, dermatologic, infectious, neoplastic, and vascular disorders. In many cases, the symptom is usually caused by degenerative disease in the spine with the compression or irritation of spinal nerve. On the other hands, there are also several announced extra-spinal causes including aneurysm, diabetes, and radiation for sciatica in a low rate. Among the extra-spinal cases, aneurysms arising from iliac vessels are sometimes developing a diagnostic confusion with the spinal causes, and delayed diagnosis can lead to poor prognosis. It is very important to pay attention weather the aneurysmal cause is involved in the symptom of sciatica.
    The Korean journal of pain. 10/2014; 27(4):360-4.
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    ABSTRACT: Bowel preparation with sodium phosphate was recently prohibited by the U.S. Food and Drug Administration. Polyethylene glycol (PEG) is safe and effective; however, it is difficult to drink. To identify an easy bowel preparation method for colonoscopy, we evaluated three different bowel preparation regimens regarding their efficacy and patient satisfaction.
    Annals of coloproctology. 10/2014; 30(5):222-7.
  • Sang Woo Kim, Kyoung Joo Cho
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    ABSTRACT: Fragile X syndrome (FXS), the most common cause of inherited human mental retardation, results from the loss of function of fragile X mental retardation protein (FMRP). To date, most researchers have thought that FXS neural pathologies are primarily caused by extreme dendritic branching and spine formation. With this rationale, several researchers attempted to prune dendritic branches and reduce the number of spines in FXS animal models. We propose that increased dendritic arborization and spinogenesis in FXS are developed rather as secondary compensatory responses to counteract the compromised postsynaptic activity during uncontrollable metabotropic glutamate receptor (mGluR)-dependent long-term depression (LTD). When postsynaptic and electrical activities become dampened in FXS, dendritic trees can increase their sensitivity to brain-derived neurotrophic factor (BDNF) by using the molecular sensor called eukaryotic elongation factor 2 (eEF2) and taking advantage of the tight coupling of mGluR and BDNF-TrkB signaling pathways. Then, this activity-dependent elevation of the BDNF signaling can strategically alter dendritic morphologies to foster branching and develop spine structures in order to improve the postsynaptic response in FXS. Our model suggests a new therapeutic rationale for FXS: correcting the postsynaptic and electrical activity first, and then repairing structural abnormalities of dendrites. Then, it may be possible to successfully fix the dendritic morphologies without affecting the survival of neurons. Our theory may also be generalized to explain aberrant dendritic structures observed in other neurobehavioral diseases, such as tuberous sclerosis, Rett syndrome, schizophrenia, and channelopathies, which accompany high postsynaptic and electrical activity.
    Medical Hypotheses 10/2014; · 1.15 Impact Factor
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    ABSTRACT: We demonstrate the control over the morphology and shape of microparticles. Two different types of microparticles (core-shell or acorn shaped) were produced by the varying the blend ratio of two immiscible biodegradable polymers in tube-type microfluidic device. Subsequent use of selective solvent extraction resulted in the formation of hollow-core, crescent-shaped and dimple surfaced microparticles. Selective solvent, glycofurol, which has been applied for intravenous injection in human body, is used instead of organic solvents which can be toxic if remained in microparticles.
    RSC Advances 09/2014; · 3.71 Impact Factor
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    ABSTRACT: Unintentionally formed nanocrystalline graphene (nc-G) can act as a useful seed for the large-area synthesis of a hexagonal boron nitride (h-BN) thin film with an atomically flat surface that is comparable to that of exfoliated single-crystal h-BN. A wafer-scale dielectric h-BN thin film was successfully synthesized on a bare sapphire substrate by assistance of nc-G, which prevented structural deformations in a chemical vapor deposition process. The growth mechanism of this nc-G-tailored h-BN thin film was systematically analyzed. This approach provides a novel method for preparing high-quality two-dimensional materials on a large surface.
    Angewandte Chemie International Edition 09/2014; · 11.34 Impact Factor
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    ABSTRACT: Unintentionally formed nanocrystalline graphene (nc-G) can act as a useful seed for the large-area synthesis of a hexagonal boron nitride (h-BN) thin film with an atomically flat surface that is comparable to that of exfoliated single-crystal h-BN. A wafer-scale dielectric h-BN thin film was successfully synthesized on a bare sapphire substrate by assistance of nc-G, which prevented structural deformations in a chemical vapor deposition process. The growth mechanism of this nc-G-tailored h-BN thin film was systematically analyzed. This approach provides a novel method for preparing high-quality two-dimensional materials on a large surface.
    Angewandte Chemie 09/2014; 126(43).
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    ABSTRACT: Remarkable enhancement of piezoelectric power output from a nanogenerator (NG) based on a zinc oxide (ZnO) thin film is achieved via native defect control. A large number of unintentionally induced point defects that act as n-type carriers in ZnO have a strong influence on screening the piezoelectric potential into a piezoelectric NG. Here, additional oxygen molecules bombarded into ZnO lead to oxygen-rich conditions, and the n-type conductivity of ZnO is decreased dramatically. The acceptor-type point defects such as zinc vacancies created during the deposition process trap n-type carriers occurring from donor-type point defects through a self-compensation mechanism. This unique insulating-type ZnO thin film-based NGs (IZ-NGs) generates output voltage around 1.5 V that is over ten times higher than that of an n-type ZnO thin film-based NG (around 0.1 V). In addition, it is found that the power output performance of the IZ-NG can be further increased by hybridizing with a p-type polymer (poly(3-hexylthiophene-2,5-diyl):phenyl-C61-butyric acid methyl ester) via surface free carrier neutralization.
    Advanced Functional Materials 09/2014; · 10.44 Impact Factor
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    ABSTRACT: Perovskite nanoparticle-based nanocomposite thin films strictly tailored using unconventional layer-by-layer (LbL) assembly in organic media for piezoelectric nanogenerators (NGs) are demonstrated. By employing sub-20-nm BaTiO3 nanoparticles stabilized by oleic acid ligands (i.e., OA-BTONPs) and carboxylic acid (COOH)-functionalized polymers, such as poly(acrylic acid) (PAA), the resulting OA-BTONP/PAA nanocomposite multilayers are prepared by exploiting the high affinity between the COOH groups of PAA and the BTONPs. The ferroelectric and piezoelectric performance of the (PAA/OA-BTONP)n thin films can be precisely controlled by altering the bilayer number, inserted polymer type, and OA-BTONP size. It is found that the LbL assembly in nonpolar solvent media can effectively increase the quantity of adsorbed OA-BTONPs, resulting in the dramatic enhancement of electric power output from the piezoelectric NGs. Furthermore, very low leakage currents are detected from the (PAA/OA-BTONP)n thin films for obtaining highly reliable power-generating performance of piezoelectric NGs.
    Advanced Functional Materials 08/2014; · 10.44 Impact Factor
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    ABSTRACT: This study was performed to investigate the discomfort reported by patients taking phosphodiesterase type 5 inhibitors (PDE5Is) in clinical practice.
    The world journal of men's health. 08/2014; 32(2):69-75.
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    ABSTRACT: We report the fabrication of a flexible and binder-free metal fibril mat-supported Si anode (Si@SFM) by a simple process. The fabricated Si@SFM anode showed a high discharge capacity, ∼3000 mAh g(-1) at a current rate of 300 mA g(-1), and exhibited stable capacity retention, 90% at a 1 C rate (2000 mA g(-1)) after 200 cycles. The rate capability of the electrode was still high even when both the charge and the discharge current rates were markedly increased at the same time (1234 mAh g(-1) for charge-discharge time of ∼12 min). Moreover, owing to its mechanical flexibility, the Si@SFM can be adopted as a key component of flexible lithium-ion batteries (LIBs). After cell packaging, the rechargeable flexible battery under bending stress showed only a little capacity fading (86% of initial capacity) at 1000 mA g(-1) over 150 cycles. These results suggest that the Si@SFM electrode is readily suitable for use in rechargeable flexible LIBs.
    ACS Applied Materials & Interfaces 07/2014; · 5.90 Impact Factor
  • Jong Hyun Choi, Seung Hun Kim, Sang Woo Kim
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    ABSTRACT: We propose a novel scheme for combining two adaptation terms of affine projection algorithms with different projection orders and step-sizes. The selection of the mixing parameter that determines the performance of the proposed combination scheme is derived by the largest decrease of the mean-square deviation. The experimental results show that the proposed algorithm exhibits a fast convergence speed and a small steady-state misalignment. Moreover, the proposed algorithm achieves a low computational complexity in the steady-state.
    Signal Processing 07/2014; 100:64–70. · 2.24 Impact Factor
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    ABSTRACT: To investigate the incidence and clinical outcome of Clostridium difficile (C. difficile) associated diarrhea (CDAD) in patients with hematologic disease.
    World journal of gastroenterology : WJG. 06/2014; 20(21):6602-7.
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    ABSTRACT: Hydrophobic sponge structure-based triboelectric nanogenerators using an inverse opal structured film for sustainable energy harvesting over a wide range of humid atmosphere have been successfully demonstrated. The output voltage and current density reached a record value of 130 V and 0.10 mA cm−2 from the device, giving over 10-fold power enhancement, compared with the flat film-based triboelectric nanogenerator.
    Advanced Materials 05/2014; · 15.41 Impact Factor
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    ABSTRACT: The drink test has been regarded as a surrogate marker of gastric accommodation. The aims of this study were to develop a novel nutrient drink test (NDT) protocol and investigate its potential for application to a clinical trial of functional dyspepsia (FD).
    Journal of neurogastroenterology and motility 04/2014; 20(2):219-27. · 2.70 Impact Factor
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    ABSTRACT: Glomus tumors are rare benign neoplasms. They typically present with a triad of severe pain, point tenderness, and cold sensitivity. Most glomus tumors will form well-circumscribed nodules, and excisional biopsy of masses detected by ultrasonography or magnetic resonance imaging of the lesion can relieve the symptoms. We describe a 30-year-old female patient with nontumorous glomus cell proliferation with clinical symptoms similar to those of glomus tumors. The lesion was treated by exploration and excision, with a satisfactory clinical outcome.
    The Journal of foot and ankle surgery: official publication of the American College of Foot and Ankle Surgeons 04/2014;

Publication Stats

2k Citations
508.77 Total Impact Points

Institutions

  • 1995–2015
    • Pohang University of Science and Technology
      • • Department of Electronic and Electrical Engineering
      • • Department of Electrical and Computer Engineering
      Geijitsu, North Gyeongsang, South Korea
  • 2014
    • Kongju National University
      • Division of Advanced Materials Engineering
      Gongju, South Chungcheong, South Korea
    • Ulsan University Hospital
      Urusan, Ulsan, South Korea
    • Brown University
      • Department of Neuroscience
      Providence, Rhode Island, United States
  • 2012–2014
    • Sungkyunkwan University
      • School of Advanced Materials Science and Engineering (AMSE)
      Sŏul, Seoul, South Korea
    • Gyeongnam National University of Science and Technology
      Sŏul, Seoul, South Korea
  • 2010–2014
    • Catholic University of Korea
      • • Department of Internal Medicine
      • • College of Medicine
      Sŏul, Seoul, South Korea
  • 2002–2014
    • Daegu University
      • Department of Biotechnology
      Daikyū, Daegu, South Korea
  • 2013
    • University of Ulsan
      • College of Medicine
      Urusan, Ulsan, South Korea
  • 2009–2013
    • Kangwon National University
      • Department of Applied Plant Sciences
      Kang-neung, Gangwon, South Korea
    • Yeungnam University
      • Department of Neurosurgery
      Daikyū, Daegu, South Korea
    • Kyungpook National University Hospital
      Sŏul, Seoul, South Korea
  • 2004–2013
    • Korea Institute of Science and Technology
      • • Clean Energy Research Center
      • • High Temperature Energy Materials Research Center
      Sŏul, Seoul, South Korea
    • Hankuk University of Foreign Studies
      • Department of Chemistry
      Sŏul, Seoul, South Korea
  • 2011
    • Chonnam National University
      • Department of Pathology
      Gwangju, Gwangju, South Korea
  • 2008–2010
    • Chung-Ang University
      • College of Pharmacy
      Sŏul, Seoul, South Korea
    • Yonsei University Hospital
      • Department of Internal Medicine
      Sŏul, Seoul, South Korea
    • Dong-A University
      • Department of Electronics Engineering
      Pusan, Busan, South Korea
    • Chungnam National University
      • Department of Chemical Engineering
      Sŏngnam, Gyeonggi Province, South Korea
    • Chosun University
      • Department of Advanced Materials Engineering
      Goyang, Gyeonggi, South Korea
    • Chonbuk National University
      • School of Medicine
      Seoul, Seoul, South Korea
  • 2005–2009
    • Inje University Paik Hospital
      • • Department of Pediatrics
      • • Department of Laboratory Medicine
      Sŏul, Seoul, South Korea
    • Cheongju University
      • Department of Electronic Engineering
      Sŏul, Seoul, South Korea
  • 2007
    • Inje University
      • College of Medicine
      Kŭmhae, South Gyeongsang, South Korea
  • 1989–2007
    • Seoul National University
      • Department of Electrical and Computer Engineering
      Sŏul, Seoul, South Korea
  • 2001–2002
    • Korea Advanced Institute of Science and Technology
      • Department of Chemistry
      Seoul, Seoul, South Korea
  • 1996
    • Korea University
      • Department of Materials Science and Engineering
      Seoul, Seoul, South Korea