Sung Hyun Kim

Institute for Basic Science, Daiden, Daejeon, South Korea

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Publications (230)564.59 Total impact

  • Sung Hyun Kim
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    ABSTRACT: This paper focuses on deriving an improved stability criterion for discrete time-delay systems via a Lyapunov–Krasovskii functional approach that takes advantage of triple summation terms. To this end, novel convex combination coefficients coupled with second-order time-varying delay terms are introduced, and the corresponding reciprocally convex approach is established with the use of the minimal number of slack matrix variables. Finally, three numerical examples are provided to illustrate the effectiveness of the proposed method, with particular regard to robustness and performance.
    Applied Mathematics and Computation 06/2015; 261. DOI:10.1016/j.amc.2015.03.086 · 1.60 Impact Factor
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    ABSTRACT: This study proposes to determine the correlation between the Volume Pulse Height (VPH) measured by nuclear emulsion and Linear Energy Transfer (LET) calculated by Monte Carlo simulation based on Geant4. The nuclear emulsion was irradiated at the National Cancer Center (NCC) with a therapeutic proton beam and was installed at 5.2 m distance from the beam nozzle structure with various thicknesses of water-equivalent material (PMMA) blocks to position with specific positions along the Bragg curve. After the beam exposure and development of the emulsion films, the films were scanned by S-UTS developed in Nagoya University. The proton tracks in the scanned films were reconstructed using the ‘NETSCAN’ method. Through this procedure, the VPH can be derived from each reconstructed proton track at each position along the Bragg curve. The VPH value indicates the magnitude of energy loss in proton track. By comparison with the simulation results obtained using Geant4, we found the correlation between the LET calculated by Monte Carlo simulation and the VPH measured by the nuclear emulsion.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 04/2015; 349. DOI:10.1016/j.nimb.2014.12.083 · 1.19 Impact Factor
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    ABSTRACT: Anabaena sensory rhodopsin transducer (ASRT) is believed to be a major player in the photo-signal transduction cascade, which is triggered by Anabaena sensory rhodopsin. Here, we characterized DNA binding activity of ASRT probed by using fluorescence correlation spectroscopy. We observed clear decrease of diffusion coefficient of DNA upon binding of ASRT. The dissociation constant, KD, of ASRT to 20 bp-long DNA fragments lied in micro-molar range and varied moderately with DNA sequence. Our results suggest that ASRT may interact with several different regions of DNA with different binding affinity for global regulation of several genes that need to be activated depending on the light illumination.
    Bioscience Biotechnology and Biochemistry 03/2015; DOI:10.1080/09168451.2015.1015950 · 1.21 Impact Factor
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    ABSTRACT: Ca-promoted Ni/MgAl2O4 catalysts prepared by co-impregnation method with different Ca/Ni ratios of 0.0-1.0 were applied to syngas production for direct reduced iron via the combined H2O and CO2 reforming (CSCR) of coke oven gas (COG). The physicochemical properties of prepared catalysts were characterized by XRD, BET, H2-chemisorption, TPR and CO2-TPD. The SEM, TGA and TEM analysis was carried out to observe the coke deposition and agglomeration of Ni particle in used catalysts. It was confirmed that Ca addition improved the Ni dispersion, strong metal-support interaction (SMSI) and CO2 adsorption of catalyst. The CSCR of COG was carried out under the reaction conditions of CH4:H2O:CO2:H2:CO:N2 = 1:1.2:0.4:2:0.3:0.3, 700-900 °C, 5 atm. The Ca-promoted 10Ni/MgAl2O4 catalysts show higher CH4 conversion and coke resistance than 10Ni/MgAl2O4 catalyst without Ca addition. In particular, 10Ni-5Ca/MgAl2O4 catalyst with Ca/Ni ratio of 0.5 showed a good catalytic activity and sinter-stability in CSCR of COG at high temperature of 900 °C due to high Ni dispersion and improved SMSI.
    Fuel 03/2015; 153. DOI:10.1016/j.fuel.2015.03.007 · 3.41 Impact Factor
  • Sung Hyun Kim, Choul Yong Park
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    ABSTRACT: To compare neodymium-doped yttrium aluminum garnet (Nd:YAG) laser capsulotomy rates between 2 different aspheric intraocular lenses, SN60WF and MI-60, in patients who underwent cataract surgery.
    Journal of the Korean Ophthalmological Society 01/2015; 56(2):190. DOI:10.3341/jkos.2015.56.2.190
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    ABSTRACT: RecA proteins form a long stable filament on a single-stranded DNA and catalyze strand exchange reaction. The stability of RecA filament changes dramatically with pH, yet its detailed mechanism is not known. Here, using a single molecule assay, we determined the binding and dissociation rates of RecA monomers at the filament ends at various pH. The pH-induced rate changes were moderate but occurred in opposite directions for binding and dissociation, resulting in a substantial increase in filament stability in lower pH. The highly charged residues in C-terminal domain do not contribute to the pH dependent stability. The stability enhancement of RecA filament in low pH may help the cell to cope with acidic stress by fine-tuning of the binding and dissociation rates without losing the highly dynamic nature of the filament required for strand exchange.
    PLoS ONE 01/2015; 10(1):e0115611. DOI:10.1371/journal.pone.0115611 · 3.53 Impact Factor
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    ABSTRACT: To date, several regulatory proteins involved in mitochondrial dynamics have been identified. However, the precise mechanism coordinating these complex processes remains unclear. Mitochondrial chaperones regulate mitochondrial function and structure. Chaperonin 10 (Cpn10) interacts with heat shock protein 60 (HSP60) and functions as a co-chaperone. In this study, we found that down-regulation of Cpn10 highly promoted mitochondrial fragmentation in SK-N-MC and SH-SY5Y neuroblastoma cells. Both genetic and chemical inhibition of Drp1 suppressed the mitochondrial fragmentation induced by Cpn10 reduction. Reactive oxygen species (ROS) generation in 3-NP-treated cells was markedly enhanced by Cpn10 knock down. Depletion of Cpn10 synergistically increased cell death in response to 3-NP treatment. Furthermore, inhibition of Drp1 recovered Cpn10-mediated mitochondrial dysfunction in 3-NP-treated cells. Moreover, an ROS scavenger suppressed cell death mediated by Cpn10 knockdown in 3-NP-treated cells. Taken together, these results showed that down-regulation of Cpn10 increased mitochondrial fragmentation and potentiated 3-NP-mediated mitochondrial dysfunction in neuroblastoma cells.
    PLoS ONE 11/2014; 9(11):e112130. DOI:10.1371/journal.pone.0112130 · 3.53 Impact Factor
  • Sung Hyun Kim
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    ABSTRACT: This paper investigates the problem of stochastic stability analysis for a class of discrete-time singular Markovian jump systems with time-varying delays and incomplete (i.e., unknown and uncertain) transition probabilities. To derive an improved delay-range-dependent stability criterion under the incomplete transition descriptions, a relaxation scheme is proposed with consideration of the free-weighting matrix method compatible with the delay partitioning technique, and its purpose is accomplished (1) by making full use of the available boundary information on incomplete transition probabilities, and (2) by employing novel slack variables that allow some useful equality constraints to be exploited.
    Journal of the Franklin Institute 10/2014; 352(1). DOI:10.1016/j.jfranklin.2014.10.012 · 2.26 Impact Factor
  • Sung Hyun Kim
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    ABSTRACT: The attention of this paper is focused on deriving less conservative stabilization conditions for Markovian jump fuzzy systems by introducing a relaxation scheme for incomplete transition probability descriptions. To this end, this paper proposes a representation approach that can express the considered conditions in terms of homogeneous polynomial of unknown and uncertain transition rates. Furthermore, based on this approach, this paper incorporates all possible slack variables into the relaxation process with consideration of the property of transition rates. Finally, three numerical examples are given to show the effectiveness of the derived stabilization conditions.
    Nonlinear Dynamics 10/2014; 78(1):691-701. DOI:10.1007/s11071-014-1469-z · 2.42 Impact Factor
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    ABSTRACT: The silicon carbide (SiC) ceramic filter is the most favorable component to remove particulate matter from hot flue gas due to its high filtration efficiency and high thermal durability. The effect of SiC powder size on the physical properties and filtration performance to prepare high-performance granular ceramic filter media was investigated in this study. Disk-type filter media were prepared by mixing ceramic components followed by physical compression and sintering. The porosity and average pore diameter in the filter media increased with increasing powder size. However, the mechanical strength decreased with increasing powder size, while it increased with increasing physical compressive force. The filter performance factor, qFM was introduced to evaluate the ceramic filter properties, and the SiC50 filter was the best of the ceramic filters prepared in this study. We also found that diffusion was a dominant collection mechanism for particles smaller than 0.7 μm, and direct interception and inertia were dominant collection mechanisms for particles larger than 0.7 μm in the SiC50 filter based on a single collector efficiency model. In addition, the predicted collection efficiencies showed reasonably good agreement with the experimental ones.Copyright 2014 American Association for Aerosol Research
    Aerosol Science and Technology 10/2014; 48(10). DOI:10.1080/02786826.2014.957755 · 3.16 Impact Factor
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    ABSTRACT: The active, stretched conformation of the RecA filament bound to single stranded DNA is required for homologous recombination. During this process, the RecA filament mediates homology search and base pair exchange with a complementary sequence. Subsequently, the RecA filament dissociates from DNA upon reaction completion. ATP binding and hydrolysis is critical throughout these processes. Little is known about the time scale, order of conversion between different co-factor bound forms during ATP hydrolysis and the associated changes in filament conformation. We used single-molecule fluorescence techniques to investigate how ATP hydrolysis is coupled with filament dynamics. For the first time, we observed real-time cooperative structural changes within the RecA filament. This cooperativity between neighboring monomers provides a time window for nucleotide cofactor exchange, which keeps the filament in the active conformation amidst continuous cycles of ATP hydrolysis.
    Journal of the American Chemical Society 09/2014; 136(42). DOI:10.1021/ja506363y · 11.44 Impact Factor
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    ABSTRACT: A highly dispersed 50 wt% Ni/MgO–Al2O3 catalyst was prepared by deposition–precipitation (DP) method for the diesel pre-reforming reaction. The pH of the precursor solution was controlled from pH 9.5 to 12.0 to examine the effects on NiO crystallite size and metal dispersion. The increase of pH of the precursor solution causes an increase of specific surface area and metal dispersion, and reduces NiO crystallite size. The pre-reforming reaction was carried out using n-tetradecane as surrogate compound of diesel. The coke formation of used catalysts was examined by TGA, TEM, SEM, and Raman analysis. The 50 wt% Ni/MgO–Al2O3 catalyst prepared at pH 11.5 showed a high catalytic activity and excellent coke resistance due to high metal dispersion (8.71%), small NiO crystallite size (3.5 nm), and strong interaction between Ni and support. Furthermore, this catalyst showed a good stability in the pre-reforming reaction at S/C ratio of 3.5 and 450 °C for 88 h.
    International Journal of Hydrogen Energy 07/2014; 39(21):10941–10950. DOI:10.1016/j.ijhydene.2014.05.041 · 2.93 Impact Factor
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    ABSTRACT: Computations of electric field and the electron drift volume of the HypTPC for E42 experiment have been accomplished with FEM and Garfield software. The double side strips field cage with shielding flange has been developed. The advantage of application a Kapton based field cage with mirror strips has been proved. According to a simulation results the spatial resolution of 300m in x-y plane and 600m in drift direction must be achieved.
    03/2014; 29. DOI:10.1142/S2010194514602221
  • Sung Hyun Kim
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    ABSTRACT: In light of the nonquadratic Lyapunov function approach, this paper investigates the problem of deriving less conservative stability and stabilization conditions for T-S fuzzy systems by considering two cases of additional constraints to impose bounds on the derivative of fuzzy weights. Specifically, in the first case where such constraints are ignored, this paper presents a method that allows the cross relationship between fuzzy weights and their derivatives to be reflected in the derivation. Then, in the second case, the reduction of the first case-based conditions to the local stabilization conditions is introduced.
    Nonlinear Dynamics 03/2014; 75(4). DOI:10.1007/s11071-013-1090-6 · 2.42 Impact Factor
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    ABSTRACT: Electrospinning is a simple and versatile process to produce polymer nanofibers, which are useful for ultrafine particle filtration. In this study, a polyurethane filter with an average fiber diameter of 150-250 nm was prepared through the electrospinning process and its filtration characteristics were investigated. We found that the electrospun fiber diameter was highly dependent on the polyurethane concentration, electric field, and tip-to-collector distance. As the polyurethane concentration, electric field, and tip-to-collector distance under the same electric field increased, the fiber diameter increased. We also found that the produced filter media had a minimum collection efficiency at particles sizes from 80 to 100 nm, which implies an electrostatic attraction between the filter and the test particles. Furthermore, we observed that interception was a predominant collection mechanism at Peclet numbers higher than 10 in nanofiber filtration for ultrafine particles. A polyurethane nanofiber filter with excellent mechanical properties was prepared, and the effect of operating conditions on fiber morphology was examined. The filter fabricated by an electrospinning process is charged and has high filtration efficiency due to electrostatic force. Therefore, it can be a good alternative to control hazardous ultrafine particles.
    Journal of the Air & Waste Management Association (1995) 03/2014; 64(3):322-9. DOI:10.1080/10962247.2013.858652 · 1.17 Impact Factor
  • Sung Hyun Kim
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    ABSTRACT: This paper is devoted to the robust stabilization problem for a class of MJLSs with mode transition probabilities taken to be partly known, unknown, and unknown but with known bounds. To meet the needs of less conservative stabilization conditions, this paper proposes a valuable approach that (1) can express the conditions in terms of matrix inequalities with homogeneous polynomial dependence on partly unknown transition probabilities and (2) can include all possible slack variables related to transition probability constraints in the relaxation process coupled with deriving a finite set of linear matrix inequalities (LMIs). Finally, two numerical examples are reported to illustrate the effectiveness of the derived stabilization conditions.
    Journal of the Franklin Institute 01/2014; · 2.26 Impact Factor
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    ABSTRACT: Jazf1 is a 27 kDa nuclear protein containing three putative zinc finger motifs that is associated with diabetes mellitus and prostate cancer; however, little is known about the role that this gene plays in regulation of metabolism. Recent evidence indicates that Jazf1 transcription factors bind to the nuclear orphan receptor TR4. This receptor regulates PEPCK, the key enzyme involved in gluconeogenesis. To elucidate Jazf1's role in metabolism, we fed a 60% fat diet for up to 15 weeks. In Jazf1 overexpression mice, weight gain was found to be significantly decreased. The expression of Jazf1 in the liver also suppressed lipid accumulation and decreased droplet size. These results suggest that Jazf1 plays a critical role in the regulation of lipid homeostasis. Finally, Jazf1 may provide a new therapeutic target in the management of obesity and diabetes.
    Biochemical and Biophysical Research Communications 12/2013; DOI:10.1016/j.bbrc.2013.12.094 · 2.28 Impact Factor
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    ABSTRACT: The study evaluated the ray tracing method [total corneal refractive power (TCRP)] in a Pentacam apparatus (Oculus, Wetzlar, Germany) for postoperative keratometry measurement after myopic photorefractive keratectomy (PRK). Manifest refraction (MR) and Pentacam analyses were performed preoperatively and at 6 months postoperatively after the PRK (STAR S4 IR CustomVue; Abbott Medical Optics/Visx) in 49 right eyes from 49 patients (age, 25.42 ± 3.51 years). Postoperative corneal power was calculated using the clinical history method (CHM) and compared with postoperatively measured simulated keratometry (simK), true net power (TNP) at 3 mm, and pupil-centered TCRP at the center, 1, 3, and 4 mm (TCRP0, TCRP1, TCRP3, and TCRP4). Vertex-distance-adjusted refractive change (delta-MR) at the corneal plane was also compared with various keratometric changes (delta-K). Postoperative TCRP0, TCRP1, TCRP3, and TCRP4 showed no significant difference compared with that of the CHM. Postoperative simK was significantly higher than that of the CHM, whereas the TNP was significantly lower compared with that of the CHM. The delta-Ks measured by simK, TNP, and TCRPs were significantly smaller than delta-MR, and delta-TCRP4 showed the least difference [mean ± SD, 0.28 ± 0.55 diopters (D)] with delta-MR. The 95% limit of agreement between delta-MR and delta-TCRP4 was -0.85 to 1.31 D. The difference between delta-TCRP4 and delta-MR was <0.5 D in 55.1% and <1.0 D in 87.8% of the eyes studied. Although postoperative TCRPs showed no significant difference with CHM, delta-MR was still underestimated after myopic PRK.
    Cornea 12/2013; DOI:10.1097/ICO.0000000000000034 · 2.36 Impact Factor
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    ABSTRACT: To compare conjunctival autograft and anchored conjunctival rotation flap techniques, in terms of recurrence and complication rates, after performing a primary pterygium surgery. Sixty patients who underwent pterygium surgery, which was performed on 1 eye (M:F = 25:35), either using conjunctival autograft (25 eyes) or anchored conjunctival rotation flap (35 eyes) techniques, were followed up postoperatively for a minimum period of 18 months. The anchored conjunctival rotation flap surgery was conducted by designing a conjunctival flap with a similar shape as that of the autograft, but with the preservation of the inferior limbal anchoring point (1 mm) by the incomplete cutting of the limbal area. After rotation of the flap around the anchoring point, the flap was tightened with sutures to cover the bare scleral area. Early postoperative complications, such as flap or graft edema and granuloma formation, were assessed. The recurrence rate of pterygium was evaluated, and a comparison was made between the 2 surgical techniques. The recurrence rate was 8.0% in the conjunctival autograft group and 8.6% in the anchored conjunctival rotational flap group (P = 0.659). However, the occurrence of flap or graft edema was lower for anchored conjunctival rotational flap surgery (14.3% vs. 72.0%, P < 0.001). No granuloma formation was observed in either group. The anchored conjunctival rotational flap surgery showed similar pterygium recurrence rates and a lower incidence of flap edema, while enabling simple recognition of flap orientation, compared with the conjunctival autograft technique.
    Cornea 10/2013; 32(12). DOI:10.1097/ICO.0b013e3182a73a48 · 2.36 Impact Factor
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    ABSTRACT: Recent studies have shown that the inhibition of histone deacetylases (HDACs) induces the differentiation of diverse cancer and stem cells, which suggests HDAC inhibitors may be good candidates for the induction of stem cell differentiation. In this study, we investigated the effects of a HDAC inhibitor, valproic acid (VPA), for the neuronal differentiation of human bone marrow-mesenchymal stromal cells (hBM-MSCs). VPA-treated MSCs had significant increases in their expression of the neuro-progenitor marker Nestin, Musashi, CD133, and GFAP, as measured by real-time PCR and immunoblot analysis. When VPA-pretreated MSCs were differentiated with neuronal induction media (VPA-dMSCs), they exhibited a cell body and dendritic morphology similar to neurons. The number and neurite length of these VPA-dMSCs significantly increased compared to differentiated MSCs (dMSCs). The VPA-dMSCs and dMSCs had significantly increased transcripts of neuronal-specific marker genes, including Nestin, Musashi, CD133, GFAP, NeuN, MAP-2, NF-M, KCNH1, KCNH5. The cells also showed a higher expression of the neuronal marker proteins Nestin and NF-M from immunocytochemical staining and immunoblot analysis. This study has shown that VPA pretreatment of hBM-MSCs, following their incubation with neuronal induction media, effectively stimulates neuronal cell differentiation to BM-MSCs.
    Neuroscience Letters 09/2013; 554. DOI:10.1016/j.neulet.2013.08.059 · 2.06 Impact Factor

Publication Stats

2k Citations
564.59 Total Impact Points


  • 2015
    • Institute for Basic Science
      Daiden, Daejeon, South Korea
  • 2007–2015
    • Sogang University
      • Department of Physics
      Sŏul, Seoul, South Korea
    • Dankook University
      • Department of Polymer Science and Engineering
      Eidō, Chungcheongbuk-do, South Korea
    • Catholic University of Korea
      • Department of Family Medicine
      Sŏul, Seoul, South Korea
  • 2012–2014
    • University of Ulsan
      • Department of Electrical Engineering
      Urusan, Ulsan, South Korea
    • Jeju National University
      Tse-tsiu, Jeju, South Korea
  • 2011–2014
    • Kyung Hee University
      • • Department of Medicine
      • • Department of Advanced Materials Engineering for Information & Electronics
      Sŏul, Seoul, South Korea
    • Korea Electronics Technology Institute
      Sŏngnam, Gyeonggi Province, South Korea
    • Chung-Ang University
      • College of Pharmacy
      Sŏul, Seoul, South Korea
    • Samsung Electro-Mechanics
      Sŏul, Seoul, South Korea
  • 2006–2014
    • Kyungpook National University
      • • Department of Physics
      • • School of Food Science and Biotechnology
      • • College of Natural Sciences
      Daikyū, Daegu, South Korea
    • University of Incheon
      • School of Mechanical System Engineering
      Sŏul, Seoul, South Korea
  • 2000–2014
    • Korea University
      • Department of Chemical and Biological Engineering
      Sŏul, Seoul, South Korea
  • 2013
    • Dongguk University
      • Department of Ophthalmology
      Sŏul, Seoul, South Korea
    • Pusan National University
      Tsau-liang-hai, Busan, South Korea
  • 2012–2013
    • Chosun University
      • • Department of Biology
      • • Department of Advanced Materials Engineering
      Gwangju, Gwangju, South Korea
  • 2009–2013
    • Weill Cornell Medical College
      • Department of Biochemistry
      New York, New York, United States
  • 2006–2013
    • Seoul National University
      • • Department of Chemistry
      • • Department of Chemical and Biological Engineering
      Sŏul, Seoul, South Korea
  • 2004–2013
    • Ewha Womans University
      • Department of Economics
      Sŏul, Seoul, South Korea
  • 2010–2012
    • Dong-A University
      • College of Medicine
      Tsau-liang-hai, Busan, South Korea
  • 2006–2011
    • Pohang University of Science and Technology
      • • Department of Electronic and Electrical Engineering
      • • Department of Electrical and Computer Engineering
      Geijitsu, Gyeongsangbuk-do, South Korea
  • 2006–2010
    • Seoul National University Bundang Hospital
      • Department of Radiology
      Sŏul, Seoul, South Korea
  • 2004–2009
    • Gwangju Institute of Science and Technology
      • Department of Life Sciences
      Gwangju, Gwangju, South Korea
  • 2008
    • Hanyang University Medical Center
      Sŏul, Seoul, South Korea
    • Yonsei University Hospital
      • Department of Internal Medicine
      Sŏul, Seoul, South Korea
  • 2003–2008
    • Korea Advanced Institute of Science and Technology
      • Department of Biological Sciences
      Sŏul, Seoul, South Korea
    • Catholic Sangji College
      Sŏul, Seoul, South Korea
    • Korea Institute of Energy Research
      Sŏul, Seoul, South Korea
  • 2005
    • Wonkwang University
      Riri, North Jeolla, South Korea
    • Bundang Jesaeng Hospital
      Sŏngnam, Gyeonggi Province, South Korea
  • 2001
    • Korea Information Society Development Institute
      Sŏngnam, Gyeonggi Province, South Korea