Hak Yong Kim

Chonbuk National University, Tsiuentcheou, Jeollabuk-do, South Korea

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Publications (41)103.36 Total impact

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    ABSTRACT: Alone, it is expected, and also was experimentally proved, that calcium carbonate and reduced graphene oxide do have negligible specific capacitance due to the chemical composition of both materials. However, synthesis of CaCO3 on the form of very thin sporadic layer attaching rGO results in dramatic increase in the specific capacitance of the obtained composite due to formation of the electrochemical double layer at the interfacial area. Moreover, the specific capacitance could be further enhanced by nitrogen-doping of the rGO sheets. Typically, a novel N-rGO/CaCO3 composite has been successfully synthesized by heat reflux strategy with graphite powder, calcium acetate and urea as raw materials.The composite was characterized by X-Ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), field-emission scanning electron microscopy (FESEM), coupled with rapid EDAX (energy dispersive analysis of X-Ray) and X-ray photoelectron spectroscopy. The utilized physiochemical characterizations indicated that the final prepared composite can be demonstrated as N-doped rGO decorated by very thin discrete layer from calcium carbonate. Supercapacitive performance of N-rGO/CaCO3 composite has been investigated by cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy in 1 M KOH solution. The results reveal that the N-rGO/CaCO3 composite delivers a large specific capacitance of as high as 214 Fg−1 and 188 Fg−1 at 5 mV s−1and 1.0 Ag−1, according to CV and galvanostatic charge-discharge tests, respectively; while the CaCO3, rGO, rGO/CaCO3, N-rGO based electrodes has a poor electrochemical performance at the same conditions. Moreover, the as-prepared composite exhibited excellent long cycle stability with about 88.7% specific capacitance retained after 10,000 cycles.
    Full-text · Article · Dec 2015 · Electrochimica Acta
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    ABSTRACT: We report a droplet-based microfluidic immunosensor for the rapid and accurate detection of melamine, an organic base that has been implicated in widescale adulteration of food products such as milk. Our melamine assay is based on the competitive reaction between native melamine and a melamine-fluorescein isothiocyanate (FITC) conjugate against an anti-hapten antibody. The adoption of fluorescence polarization, allows the quantification of melamine in a more direct and rapid manner than established heterogeneous methods based on liquid chromatography, mass spectrometry, and enzyme-linked immunosorbent assay (ELISA). The detection protocol provides a limit of detection of 300 ppb, which is below the maximum allowable melamine levels (2.5 ppm) defined by the U.S. Food and Drug Administration and the European Commission to a significant extent.
    No preview · Article · Dec 2015 · Biosensors & Bioelectronics
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    ABSTRACT: In this study, a facile, controllable, and efficient process (electrospinning followed by calcination at 1100 °C under argon atmosphere) is developed for in-situ synthesis of Ni/N-CNFs catalyst as thin film immobilized on graphite disk. Moreover, the influence of nitrogen content on the catalytic activity of the supported Ni-doped CNFs toward methanol oxidation was investigated. The composition and morphology of the prepared catalysts were characterized by XRD, EDX, FE-SEM and TEM techniques. The electrocatalytic activity and stability were evaluated by cyclic voltammetry (CV) and chronoamperometry, respectively. Compared to the powder form, the results indicated that the proposed in-situ immobilization of the introduced nanofibers on graphite disk reveals distinct enhancement in the electrocatalytic activity due to merging of the underneath nanofibers with the graphite support which eliminates the interfacial resistance. Numerically, the detected maximum current density was 270.44 and 80.59 mA/cm2 for Ni/N-CNFs/graphite and unsupported nanofibers, respectively. Moreover, the obtained results have also showed that nitrogen doping effectively enhances the electrocatalytic activity and stability of Ni/CNFs toward methanol oxidation in the alkaline medium. However, due to the influence of methanol content on the water-alcohol mixture fluidity, the optimum methanol concentration was observed to be 0.5 and 5.0 M for the supported and unsupported nanofibers, respectively. Overall, this study opens new avenue to prepare one-pot current collector/electrode plate to be utilized in the fuel cell technology.
    Full-text · Article · Nov 2015 · International Journal of Hydrogen Energy
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    Hye Kyoung Shin · Mira Park · Hak Yong Kim · Soo-Jin Park
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    ABSTRACT: This work evaluated the effect of various amounts of tension on polyacrylonitrile (PAN) precursor fibers during electron beam irradiation (EBI) stabilization. X-ray diffraction (XRD), tensile testing, and scanning electron microscopy (SEM) were implemented to determine the effects of tension on the PAN fibers. During the stabilization process, the fibers shrunk due to a loss of molecular alignment, and the addition of tension acting on the PAN fibers during stabilization was proposed to address this issue. In this work, PAN fibers were stabilized by EBI under various loads. It was found from the XRD data that tension led to the development of crystalline structures during EBI stabilization. From the tensile test, it was found that tension led to a small increase in strength due to conversion of disordered structures into ordered structures in the fibers. © 2015 The Korean Society of Industrial and Engineering Chemistry.
    Full-text · Article · Aug 2015 · Journal of Industrial & Engineering Chemistry
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    ABSTRACT: Novel luminescent and amorphous La2O3-ZrO2 : Eu3+ (LZE) nanofibrous membranes with robust softness are fabricated for the first time via a facile electrospinning technique. By employing zirconium oxide incorporation, the as-prepared lanthanum oxide nanofibrous membranes can be dramatically changed from the extreme fragility to robust softness. Meanwhile, the softness and luminescent performance of LZE nanofibrous membranes can be finely controlled by regulating the doping concentration of zirconium oxide and europium in lanthanum oxide nanofibers. Additionally, the crystal structure analysis using X-ray diffractometer and high resolution transmission electron microscopy measurements have confirmed the correlation between the amorphous structure and softness. Furthermore, LZE membranes show the characteristic emission of Eu3+ corresponding to 5D0, 1-7F0, 1, 2, 3, 4 transitions due to an efficient energy transfer from O2- to Eu3+. The LZE nanofibrous membranes with the optimum doping Eu3+ concentration of 3 mol%, the as-prepared LZE membranes exhibit excellent softness and luminescent properties, which make the materials have potential applications in fluorescent lamps and field emission displays.
    Full-text · Article · Jun 2015 · Nanoscale
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    ABSTRACT: In this study, we report the preparation and comparison of the rosin based thin films and electrospun fibers in terms of their formation and characterizations. Rosin in the form of thin films and fibers can be obtained via wet casting method and electrospinning process, respectively. Systematic experiments were performed to study the morphology, structure and thermal properties of the rosin thin films and electrospun fibers. Finally, in order to understand the accurate mass values of rosin in the different morphologies, we performed matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) spectroscopy. The rosin thin film prepared via wet casting method exhibited very smooth surfaces whereas the electrospun fibers were continuous without any beads over long distances. The MALDI-TOF data revealed that the most intense peak in the molecular weight of rosin components is about 302 for the rosin powder, thin film and fibers. On the other hand, some of the higher molecular component can also be observed for electrospun rosin fibers owing to the structural morphology. The present study demonstrated that the full structural characterization of the molecular species present in these different forms of rosin.
    No preview · Article · Apr 2015 · Journal of Nanoscience and Nanotechnology
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    ABSTRACT: Poly(ɛ-caprolactone) (PCL)-containing rosin nanofibers were prepared via electrospinning technique for biomedical applications. To improve the biocompatibility properties, rosin was blended into PCL to prepare nanofibers. Nanofibers mats were prepared with different concentrations of rosin. The morphology, structure, and thermal properties of the resultant PCL/rosin nanofibers were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetry (TGA) analysis. SEM images revealed that the nanofibers were well-oriented and had good incorporation of rosin. FTIR results indicated the various bonding groups of PCL/rosin nanofibers with stable structure. TGA analysis revealed that the onset degradation temperature was decreased with increasing rosin content in the nanofibers. The bactericidal activity of PCL/rosin nanofibers was also investigated. These results indicate that the PCL blended with rosin nanofibers can be utilized as a promising candidate material for many biomedical applications.
    No preview · Article · Feb 2014 · Macromolecular Research
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    ABSTRACT: Feline leukemia virus (FeLV) causes a range of neoplastic and degenerative diseases in cats. For the more sensitive and convenient diagnosis of the disease, we prepared monoclonal antibodies specific to the FeLV p27 to develop a rapid diagnostic test with enhanced sensitivity and specificity. Among these antibodies, we identified two clones-hybridomas 8F8B5 and 8G7D1-that specifically bound to FeLV and were very suitable for application to a diagnostic kit. The affinity constants of 8F8B5 and 8G7D1 were 0.35 × 109 and 0.86 × 109, respectively. To investigate the diagnostic characteristics of the rapid kit based on these antibodies, we carried out several clinical studies. In an experiment of analytical sensitivity, the detection threshold of the rapid diagnostic test was 2 ng/mL for recombinant p27 and was 12.5 × 104 IU/mL for FeLV. In an evaluation using 252 cases of cat's sera, the kit showed 0.88 kappa value compared with PCR, indicating a significant correlation between the rapid diagnostic test and PCR method. The sensitivity and specificity of the kit were 95.2% (20/21) and 98.5% (257/261), respectively. Thus, the rapid diagnostic test would be a suitable diagnostic tool for rapid detection of FeLV progressive infection in cats.
    Full-text · Article · Oct 2013 · Journal of veterinary science (Suwŏn-si, Korea)
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    ABSTRACT: Electrospun nylon-6/chitosan (nylon-6/Ch) nanofibers were prepared by nanospider technology. Quater-nary ammonium salts as antibacterial agent were immobilized onto electrospun nylon-6/Ch nanofibers via surface modi-fication by soaking the mat in aqueous solution of glycidyltrimethylammonium chloride (GTMAC) at room temperature overnight to give nylon-6/N-[(2-hydroxy-3-trimethylammonium)propyl] chitosan chloride (nylon-6/HTCC). The mor-phological, structural and thermal properties of the nylon-6/ch nanofibers were studied by field-emission scanning elec-tron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, and thermo-gravimetric analysis (TGA). Biological screening has demonstrated the antibacterial activity of the electrospun nanofi-bers against Gram negative bacteria, Escherichia coli 35218, and Pseudomonas aeruginosa and Gram positive bacteria, Staphylococcus aureus 24213 among the tested microbes. Thus, the study ascertains the value of the use of electrospun nanofibers, which could be of considerable interest to the development of new antibacterial materials for biomedical applications.
    Full-text · Article · Feb 2013 · Korean Journal of Chemical Engineering
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    ABSTRACT: Modifications in the tumor microenvironment (TME) play a major role in the establishment, progression, and metastasis of cancer. Matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) is a powerful technique that enables the simultaneous identification and localization of biological compounds within tissues. To detect markers of early TME remodeling in invasive breast cancer, we used MALDI-MSI to compare the molecular profiles of tissues from the breast cancer interface zone, tumor zone, and normal-tissue zone. Using direct-tissue MALDI tandem mass spectrometry (MS/MS), we identified immunoglobulin heavy constant alpha 2 (IGHA2) as a new, zone-specific protein in the breast TME. The zone-specific expression of IGHA2 was verified by immunoblotting and immunohistochemical analysis. IGHA2 expression was consistently positive in tumor cells that were metastatic to regional nodes, with intense expression along the cytoplasmic borders. As a factor related to an increased percentage of nodes with tumor metastasis, IGHA2 expression was upregulated 3.745-fold in cases with an increased number of cancerous nodes (p = 0.0468). Our results provide the first evidence of IGHA2 as a marker of the early process of TME remodeling in invasive breast cancer. Furthermore, IGHA2 may be a novel marker for regional metastases in the lymph nodes of patients with breast cancer.
    No preview · Article · Aug 2012 · Journal of Proteome Research
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    ABSTRACT: Nanobiocatalysis has received growing attention for use in commercial applications. We investigated the efficiency, stability, and reusability of laccase-poly(lactic-co-glycolic acid) (PLGA) nanofiber for diclofenac transformation. NH stretching vibrations (3400-3500 cm(-1) and 1560 cm(-1)) in FT-IR spectra confirmed immobilization of laccase on PLGA nanofibers. The relative activity of immobilized laccase was 82% that of free laccase. Immobilized laccase had better storage, pH, and thermal stability than free laccase. The immobilized laccase produced complete diclofenac transformation in three reuse cycles, which was extended to 6 cycles in the presence of syringaldehyde. Results suggest that laccase-PLGA nanofiber may be useful for removing diclofenac from aqueous sources and has potential for other commercial applications.
    Full-text · Article · Jul 2012 · Enzyme and Microbial Technology
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    ABSTRACT: Plasmodium falciparum and P. vivax malaria are endemic to many parts of the world and humans can be co-infected with both species. Because each Plasmodium species has different biological and clinical characteristics, accurate differentiation of the infecting species is essential for effective treatment. Therefore, we produced three monoclonal antibodies that recognize the lactate dehydrogenase of P. falciparum, P. vivax, or both to develop the first P. falciparum, P. vivax, and mixed-species infections malaria antigen detection kit. The detection limits of this kit were 150 and 250 parasites/μL for P. falciparum and P. vivax, respectively, and the kit was able to detect mixed-species infections. The sensitivity and specificity of this kit was assessed with 722 clinical specimens. Our results showed that its sensitivities for P. falciparum, P. vivax, and mixed-species infection were 96.5%, 95.3%, and 85.7%, respectively. In addition, its specificity was high (99.4%).
    Full-text · Article · Dec 2011 · The American journal of tropical medicine and hygiene
  • Hyun-Il Shin · Hak Yong Kim · Tae-Ju Cho
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    ABSTRACT: Turnip yellow mosaic virus (TYMV) is a spherical plant virus that has a single 6.3 kb positive strand RNA. The genomic RNA has a tRNA-like structure (TLS) at the 3'-end. The 3'-TLS and hairpins in the 5'-untranslated region supposedly serve as packaging signals; however, recent studies have shown that they do not play a role in TYMV RNA packaging. In this study, we focused on packaging signals by examining a series of deletion mutants of TYMV. Analysis of encapsidated viral RNA after agroinfiltration of the deletion constructs into Nicotiana benthamiana showed that the mutant RNA lacking the protease (Pro)/helicase (Hel) region was not encapsidated by the coat proteins provided in trans, implicating that a packaging signal lies in the Pro/Hel region. Examination of two Pro(-)Hel(-) mutants showed that protein activity from the Pro/Hel domains was dispensable for the packaging of the non-replicating TYMV RNA. In contrast, the mutant TYMV RNA lacking the Pro/Hel region was efficiently encapsidated when the mutant TYMV was co-introduced with a wild-type TYMV, suggesting that packaging mechanisms might differ depending on whether the virus is replicating or not.
    No preview · Article · May 2010 · Moleculer Cells
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    ABSTRACT: Kawasaki disease (KD) is an acute systemic vasculitis in children which causes coronary arterial dilatation (CAD) and gallbladder distension (GBD). There is a dearth of investigating the relationship between the severity of KD and GBD with lipid profiles. A total of 80 patients with 'complete KD' who were diagnosed from January 2005 to May 2009 was enrolled in this study. Serum cholesterol {total, high density lipoprotein-cholesterol (HDL-C) and low density lipoprotein-cholesterol (LDL-C)}, triglyceride (TG), complete blood count, inflammation markers {erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)} were measured at the time of admission during febrile period. Echocardiography and abdominal sonogram were performed in all patients to determine CAD and gallbladder size. According to GBD, patients with KD were classified as patients with GBD and patients without GBD. Between two groups, demographic and clinical data were analyzed. The serum level of LDL-C was significantly lower in patients with GBD (p=0.03) compared with patients without GBD or febrile control. There was no significant difference in inflammatory indices between patients with GBD and patients without GBD. GBD was not significant risk factor of CAD in this study (odds ratio=2.0, 95% confidence interval=0.82-5.3, p=0.16). This is the first study that highlights the relationship between the GBD and lipid metabolism in patients with KD. This study provides clinical insights about potential mechanism underpinning the relationship between the GBD and lipid metabolism.
    Full-text · Article · Mar 2010 · Korean Circulation Journal
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    ABSTRACT: The specific molecular profiles of ovarian cancer interface zones (IZ), the region between tumors and normal tissues, were evaluated using a new method involving matrix-assisted laser desorption/ionization (MALDI)-imaging mass spectrometry (IMS). We analyzed three ovarian serous carcinomas using MALDI-IMS. Principal component analysis (PCA) was used to evaluate the quality of tissue spatial features based on MALDI-IMS, and for analysis of large data sets of MALDI-IMS. Two-dimensional gel electrophoresis and fluorescence microscopy were used to verify interface-specific proteins. Unique profiles were identified for the tumors, the normal zone, and the IZ. Through MALDI analysis, two interface-specific proteins, plastin 2 and peroxiredoxin 1 (PRDX 1), were identified as differentially regulated between zones. Fluorescence microscopy revealed high expression levels of plastin 2 and PRDX 1 along the IZ of ovarian tumors. This comparative proteomics study using tissue MALDI-IMS suggested that the IZ is different from the adjacent tumor and normal zones, and that plastin 2 and PRDX 1 may be interface markers specific to ovarian tumors.
    No preview · Article · Oct 2009 · Journal of Proteome Research
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    Young-Sun Do · Hak Yong Kim · Mee Kyung Namgoong
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    ABSTRACT: Kimura's disease is a chronic inflammatory disorder of unknown etiology. A 14 year old boy suffering from steroid dependant nephrotic syndrome, was presented with relapsing painless subcutaneous masses on the left buccal area. Blood analysis showed increased IgE and eosinophilia. During 4 years follow up, he was been treated by low dose steroid and short term cyclosporine. Consequently, frequent relapses of subcutaneous masses and nephrotic syndrome has been relieved. Cyclosporine treatment combined with steroid may be useful for preventing frequent relapse of Kimura's disease.
    Full-text · Article · Jan 2009 · Journal of the Korean Society of Pediatric Nephrology
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    ABSTRACT: In the present study, silver metal nanofibers have been successfully prepared by using the electrospinning technique. Silver nanofibers have been produced by electrospinning a sol-gel consisting of poly(vinyl alcohol) and silver nitrate. The dried nanofiber mats have been calcined at 850 degrees C in an argon atmosphere. The produced nanofibers do have distinct plasmon resonance compared with the reported silver nanoparticles. Contrary to the introduced shapes of silver nanoparticles, the nanofibers have a blue-shifted plasmon resonance at 330 nm. Moreover, the optical properties study indicated that the synthesized nanofibers have two band gap energies of 0.75 and 2.34 eV. An investigation of the electrical conductivity behavior of the obtained nanofibers shows thermal hystersis. These privileged physical features greatly widen the applications of the prepared nanofibers in various fields.
    No preview · Article · Oct 2008 · Langmuir
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    ABSTRACT: We have constructed and analyzed a protein-protein interaction network from the Saccharomyces cerevisiae genome by using public genomic sequences. This provides a starting point for the construction of protein network analysis, leading to a better understanding of the functions of uncharacterized proteins and of the cellular functions of modules the networks. We acquired a highly filtered reliable protein interaction database through filtering by using subcellular localization and by using protein domains. The protein-protein interaction network constructed from the highly filtered protein interaction database shows scale-free and hierarchical properties as most networks in complex systems. For the prediction of unannotated proteins, we employed a modified Chi-square method based on neighborhood counting within structural modules and we predicted and elucidated the functions of the 98 unannotated proteins with high certainty.
    Preview · Article · Nov 2007 · Journal- Korean Physical Society
  • Tae Ho Kang · Jae Soo Yoo · Hak Yong Kim
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    ABSTRACT: Biological sequences such as DNA and amino acid sequences typically contain a large number of items. They have contiguous sequences that ordinarily consist of more than hundreds of frequent items. In biological sequences analysis (BSA), a frequent contiguous sequence search is one of the most important operations. Many studies have been done for mining sequential patterns efficiently. In recent years, the MacosVSpan algorithm was proposed based on the idea of the prefixSpan algorithm to significantly reduce its recursive process. However, the algorithm is inefficient for mining frequent contiguous sequences from long biological data sequences. In this paper, we propose an efficient method to mine maximal frequent contiguous sequences in large biological data sequences by constructing the spanning tree with a fixed length. To verify the superiority of the proposed method, we perform experiments in various environments. The experiments show that the proposed method is much more efficient than MacosVSpan in terms of retrieval performance.
    No preview · Conference Paper · Nov 2007
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    ABSTRACT: Angiogenin, a potent angiogenic factor, binds to endothelial cells and is endocytosed and rapidly translocated to and concentrated in the nucleolus where it binds to DNA. In this study, we report that angiogenin induces transient phosphorylation of protein kinase B/Akt in cultured human umbilical vein endothelial (HUVE) cells. LY294002 inhibits the angiogenin-induced protein kinase B/Akt activation and also angiogenin-induced cell migration in vitro as well as angiogenesis in chick embryo chorioallantoic membrane in vivo without affecting nuclear translocation of angiogenin in HUVE cells. These results suggest that cross-talk between angiogenin and protein kinase B/Akt signaling pathways is essential for angiogenin-induced angiogenesis in vitro and in vivo, and that angiogenin-induced PKB/Akt activation is independent of nuclear translocation of angiogenin in HUVE cells.
    No preview · Article · Feb 2007 · Biochemical and Biophysical Research Communications

Publication Stats

1k Citations
103.36 Total Impact Points

Institutions

  • 2004-2015
    • Chonbuk National University
      • • Department of Organic Materials and Fiber Engineering
      • • Department of Biotechnology
      Tsiuentcheou, Jeollabuk-do, South Korea
  • 2000-2015
    • Chungbuk National University
      • • Department of Biochemistry
      • • Division of Life Sciences
      Chinsen, Chungcheongbuk-do, South Korea
  • 2009-2010
    • Wonju Severance Christian Hospital
      Genshū, Gangwon, South Korea
  • 2005
    • Chonnam National University
      Gwangju, Gwangju, South Korea
  • 1996
    • University of Connecticut
      • Department of Molecular and Cell Biology
      Storrs, Connecticut, United States
    • University of California, Davis
      • Area of Chemical Biology
      Davis, California, United States