Sung Hyun Kim

University of Ulsan, Urusan, Ulsan, South Korea

Are you Sung Hyun Kim?

Claim your profile

Publications (217)540.82 Total impact

  • [Show abstract] [Hide abstract]
    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. · 3.53 Impact Factor
  • Sung Hyun Kim
    [Show abstract] [Hide abstract]
    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; · 2.26 Impact Factor
  • [Show abstract] [Hide abstract]
    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). · 3.16 Impact Factor
  • Sung Hyun Kim
    Nonlinear Dynamics 10/2014; 78(1):691-701. · 2.42 Impact Factor
  • [Show abstract] [Hide abstract]
    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; · 11.44 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    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. · 2.93 Impact Factor
  • [Show abstract] [Hide abstract]
    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.
    International Journal of Modern Physics: Conference Series. 03/2014; 29.
  • [Show abstract] [Hide abstract]
    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. · 1.17 Impact Factor
  • Sung Hyun Kim
    [Show abstract] [Hide abstract]
    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
  • Sung Hyun Kim
    [Show abstract] [Hide abstract]
    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 01/2014; 75(4). · 2.42 Impact Factor
  • [Show abstract] [Hide abstract]
    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; · 2.28 Impact Factor
  • [Show abstract] [Hide abstract]
    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; · 1.75 Impact Factor
  • [Show abstract] [Hide abstract]
    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; · 1.75 Impact Factor
  • [Show abstract] [Hide abstract]
    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; · 2.06 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We propose a facile method to control the growth and areal density of zinc-oxide (ZnO) nanowire arrays using gold or silver films deposited on aluminum-doped ZnO (AZO) layers coated on glass substrates. Nanowires exceeding 5 μm in length grew on both the glass/AZO-layer and on the glass/AZO-layer/Au-film where the areal array density was controlled primarily by changing the annealing temperature. In contrast, the nanowire arrays grew only on the AZO surface but not on the Ag film owing to the formation of an Ag-oxide layer. We fabricated field emitter de-vices with density controlled ZnO nanowire arrays and low turn-on electric field of ∼6 V/μm and a field enhancement factor of up to 1188 were obtained with density controlled ZnO nanowire arrays. C 2013 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. [http://dx.doi.org/10.1063/1.4824311]
  • [Show abstract] [Hide abstract]
    ABSTRACT: The effects of the isocyanate (NCO) index and blowing agent on the morphology, mechanical strength, thermal conductivity and thermal stability of the polyisocyanurate-polyurethane (PIR-PUR) foams were investigated. When the NCO index was increased, the isocyanurate ring content in the PIR-PUR foams was found to be increased regardless the type of blowing agents. As a results, the thermal stability of the PIR-PUR foams was improved. When the isocyanurate ring content in the PIR-PUR foams was increased, the cell size was slightly decreased. The decreased cell size of the foams affected the decrease in the thermal conductivity of the PIR-PUR foams regardless the type of the blowing agents. From the results of thermogravimetric analysis (TGA), the thermal stability of the PIR-PUR foams was found to increase with an increase in the NCO index. When the NCO index was 200, the compressive strength was maximal for the PIR-PUR foams regardless the type of the blowing agents. The compressive strength of the foams blown by cyclopentane was higher than that of the water blown foams. From the above results, it is suggested that the thermal insulation property and thermal stability of the PIR-PUR foams increased with an increase in the NCO index. However, the compressive strength of the PIR-PUR foams showed maximum value at a specific NCO index.
    Macromolecular Research 08/2013; 21(8). · 1.68 Impact Factor
  • Sung Hyun Kim
    [Show abstract] [Hide abstract]
    ABSTRACT: Based on the fuzzy weighting-dependent Lyapunov function, this paper proposes a method to drive the relaxed stabilization condition for continuous-time Takagi-Sugeno (T-S) fuzzy control systems without resorting to elimination and bounding techniques. Here, to achieve an improved robust H∞ performance while enhancing the interactions among the fuzzy subsystems, this paper proposes a valuable relaxation technique that is capable of incorporating the derivatives of fuzzy weighting functions to the relaxation process. Finally, three examples are given to verify the effectiveness of the proposed method.
    IEEE Transactions on Fuzzy Systems 08/2013; 21(4):761-766. · 6.31 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this study, the effects of hybrid fillers on the electrical conductivity and electromagnetic interference shielding efficiency (EMI SE) of the polypropylene (PP)/Ni-coated carbon fiber (NCCF) composites with the second fillers, such as multi-walled carbon nanotube (MWCNT), carbon black and TiO2, were investigated. The morphological behavior showed that the NCCF and the second fillers, such as MWCNT, carbon black and TiO2, seemed to disperse evenly in the PP phase. Among the PP/NCCF composites with MWCNT, carbon black and TiO2, the PP/NCCF/TiO2 composites showed the higher electrical conductivity and EMI SE compared with those of the PP/NCCF/MWCNT and PP/NCCF/carbon black composites. This was the case because TiO2 has high dielectric constant with dominant dipolar polarization. The estimated EMI SE values of the PP/NCCF composites with MWCNT, carbon black and TiO2 are in good agreement with the experimentally obtained values of the composites. Based on the electrical properties of the composites, it was suggested that TiO2 was the most effective second filler when it was hybridized with the NCCF of the PP/NCCF/TiO2 composite. Based on the analysis of the flexural modulus, the PP/NCCF/MWCNT composite had a higher flexural modulus than the PP/NCCF/TiO2 and PP/NCCF/carbon black composites because of the higher aspect ratio of the MWCNT.
    Macromolecular Research 08/2013; 21(8). · 1.68 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Several inflammatory response materials could be used for prediction of prognosis of cancer patients. The neutrophil lymphocyte ratio (NLR), and the platelet lymphocyte ratio (PLR) have been introduced for prognostic scoring system in various cancers. The objective of this study was to determine whether the NLR or the PLR would predict the clinical outcomes in advanced gastric cancer patients treated with oxaliplatin/ 5-fluorouracil (FOLFOX). The study population consisted of 174 advanced gastric cancer patients. Patients were treated with 85 mg/m2 of oxaliplatin as a 2-h infusion at day 1 plus 20 mg/m2 of leucovorin over 10 min, followed by 5-FU bolus 400 mg/m2 and 22-h continuous infusion of 600 mg/m2 at days 1-2. Treatment was repeated in 2-week intervals. The NLR and PLR were calculated from complete blood counts in laboratory test before and after first cycle of chemotherapy. NLR was a useful prognostic biomarker for predicting inferior overall survival (OS) (p = 0.005), but was not associated with progression free survival (PFS) (p = 0.461). The normalization of NLR after one cycle of chemotherapy was found to be in association with significant improvement in PFS (5.3 months vs. 2.4 months, p < 0.001), and OS (11.9 months vs. 4.6 months, p < 0.001). The normalization of PLR was also associated with longer PFS (5.6 months vs. 3.4 months, p = 0.006), and OS (16.9 months vs. 10.9 months, p = 0.002). In multivariate analysis, changes in NLR were associated with PFS (Hazard ratio (HR): 2.297, 95% confidence interval (CI): 1.429-3.693, p = 0.001). The NLR, (HR: 0.245, 95% CI: 0.092-0.633, p = 0.004), PLR (HR: 0.347, 95%CI: 0.142-0.847, p = 0.020), changes in NLR (HR: 2.468, 95% CI: 1.567-3.886, p < 0.001), and changes in PLR (HR: 1.473, 95%CI: 1.038-2.090, p = 0.030) were independent prognostic markers for OS. This study demonstrates that NLR, PLR, and changes in NLR or PLR are independent prognostic factor for OS in patients with advanced gastric cancer treated with chemotherapy. These specific factors may also help in identifying the patients, who are more sensitive to FOLFOX regimen.
    BMC Cancer 07/2013; 13(1):350. · 3.32 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Working memory is an essential component of higher cognitive function, and its impairment is a core symptom of multiple CNS disorders, including schizophrenia. Neuronal mechanisms supporting working memory under normal conditions have been described and include persistent, high-frequency activity of prefrontal cortical neurons. However, little is known about the molecular and cellular basis of working memory dysfunction in the context of neuropsychiatric disorders. To elucidate synaptic and neuronal mechanisms of working memory dysfunction, we have performed a comprehensive analysis of a mouse model of schizophrenia, the forebrain-specific calcineurin knock-out mouse. Biochemical analyses of cortical tissue from these mice revealed a pronounced hyperphosphorylation of synaptic vesicle cycling proteins known to be necessary for high-frequency synaptic transmission. Examination of the synaptic vesicle cycle in calcineurin-deficient neurons demonstrated an impairment of vesicle release enhancement during periods of intense stimulation. Moreover, brain slice and in vivo electrophysiological analyses showed that loss of calcineurin leads to a gene dose-dependent disruption of high-frequency synaptic transmission and network activity in the PFC, correlating with selective working memory impairment. Finally, we showed that levels of dynamin I, a key presynaptic protein and calcineurin substrate, are significantly reduced in prefrontal cortical samples from schizophrenia patients, extending the disease relevance of our findings. Our data provide support for a model in which impaired synaptic vesicle cycling represents a critical node for disease pathologies underlying the cognitive deficits in schizophrenia.
    Journal of Neuroscience 07/2013; 33(27):10938-49. · 6.75 Impact Factor

Publication Stats

2k Citations
540.82 Total Impact Points

Institutions

  • 2012–2014
    • University of Ulsan
      • Department of Electrical Engineering
      Urusan, Ulsan, South Korea
    • Jeju National University
      Tse-tsiu, Jeju, 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
    • Pusan National University
      Tsau-liang-hai, Busan, South Korea
    • Albert Einstein College of Medicine
      • Department of Ophthalmology & Visual Sciences
      New York City, New York, United States
    • Sogang University
      Sŏul, Seoul, South Korea
  • 2011–2013
    • Kyung Hee University
      • Department of Advanced Materials Engineering for Information & Electronics
      Sŏul, Seoul, South Korea
    • Chung-Ang University
      • College of Pharmacy
      Sŏul, Seoul, South Korea
    • Korea Electronics Technology Institute
      Sŏngnam, Gyeonggi Province, South Korea
    • Samsung Electro-Mechanics
      Sŏul, Seoul, South Korea
  • 2009–2013
    • Weill Cornell Medical College
      • Department of Biochemistry
      New York City, NY, 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
    • Dong-A University
      • College of Medicine
      Tsau-liang-hai, Busan, South Korea
    • Purdue University
      • School of Civil Engineering
      West Lafayette, IN, United States
  • 2007–2010
    • Seoul National University Bundang Hospital
      • Department of Radiology
      Sŏul, Seoul, South Korea
    • Catholic University of Korea
      • Department of Family Medicine
      Sŏul, Seoul, South Korea
    • Kyonggi University
      • Department of Environmental Energy System Engineering
      Sŏul, Seoul, South Korea
  • 2006–2010
    • Pohang University of Science and Technology
      • Department of Electrical and Computer Engineering
      Andong, North Gyeongsang, South Korea
  • 2004–2009
    • Gwangju Institute of Science and Technology
      • Department of Life Sciences
      Gwangju, Gwangju, South Korea
  • 2008
    • Yonsei University Hospital
      • Department of Internal Medicine
      Sŏul, Seoul, South Korea
    • Hanyang University Medical Center
      Sŏul, Seoul, South Korea
  • 2003–2007
    • Korea Advanced Institute of Science and Technology
      • Department of Biological Sciences
      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