Jeong Hun Kim

Ulsan National Institute of Science and Technology, Ulsan, Ulsan, South Korea

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Publications (204)599.03 Total impact

  • Dong Hyun Jo · Jin Hyoung Kim · Tae Geol Lee · Jeong Hun Kim
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    ABSTRACT: Nanoparticles are widely utilized in the fields of medicine and industry. Accordingly, it is vital to deliberately assess the toxicity of nanoparticles in the development of nanoparticle-related products and therapeutic agents. This chapter reviews in vitro and in vivo procedures for the assessment of the toxicity of nanoparticles. As the first step, various in vitro and in vivo procedures are listed and discussed with suggestions from various researchers. Furthermore, we discuss the issues regarding the determination of toxicity assays for the evaluation of the toxicity of nanoparticles. Especially, these assays are valuable tools to investigate the differential effects of nanoparticles of various sizes and different surface modification. We expect that this chapter can be a stepping stone for further discussion about the toxicity of nanoparticles and will help researchers to evaluate the toxicity of nanoparticles efficiently. © Springer International Publishing Switzerland 2016. All rights reserved.
    No preview · Chapter · Jan 2016
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    ABSTRACT: The manipulation of droplets is used in a wide range of applications, from lab-on-a-chip devices to bioinspired functional surfaces. Although a variety of droplet manipulation techniques have been proposed, active, fast and reversible manipulation of pure discrete droplets remains elusive due to the technical limitations of previous techniques. Here, we describe a novel technique that enables active, fast, precise and reversible control over the position and motion of a pure discrete droplet with only a permanent magnet by utilizing a magnetically responsive flexible film possessing actuating hierarchical pillars on the surface. This magnetically responsive surface shows reliable actuating capabilities with immediate field responses and maximum tilting angles of ∼90°. Furthermore, the magnetic responsive film exhibits superhydrophobicity regardless of tilting angles of the actuating pillars. Using this magnetically responsive film, we demonstrate active and reversible manipulation of droplets with a remote magnetic force.
    Preview · Article · Dec 2015 · Scientific Reports
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    ABSTRACT: Objectives To evaluate the mobile health applications (apps) developed by a single tertiary hospital in Korea with a particular focus on quality and patient safety. Methods Twenty-three mobile health apps developed by Asan Medical Center were selected for analysis after exclusion of the apps without any relationship with healthcare or clinical workflow, the apps for individual usage, and the mobile Web apps. Two clinical informaticians independently evaluated the apps with respect to the six aims for quality improvement suggested by the United States Institute of Medicine. All discrepancies were resolved after discussion by the two reviewers. The six aims observed in the apps were reviewed and compared by target users. Results Eleven apps targeted patients, the other 12 were designed for healthcare providers. Among the apps for patients, one app also had functions for healthcare providers. 'My cancer diary' and 'My chart in my hand' apps matched all the six aims. Of the six aims, Timeliness was the most frequently observed (20 apps), and Equity was the least observed (6 apps). Timeliness (10/11 vs. 10/12) and Patient safety (10/11 vs. 9/12) were frequently observed in both groups. In the apps for patients, Patient-centeredness (10/11 vs. 2/12) and Equity (6/11 vs. 0/12) were more frequent but Efficiency (5/11 vs. 10/12) was less frequent. Conclusions Most of the six aims were observed in the apps, but the extent of coverage varied. Further studies, evaluating the extent to which they improve quality are needed.
    Full-text · Article · Oct 2015 · Healthcare Informatics Research
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    ABSTRACT: Changes in the carrier mobility of tensile strained Si and SiGe nanowires (NWs) were examined using an electrical push-to-pull device (E-PTP, Hysitron). The changes were found to be closely related to the chemical structure at the surface, likely defect states. As tensile strain is increased, the resistivity of SiGe NWs deceases in a linearly manner. However, the corresponding values for Si NWs increased with increasing tensile strain, which is closely related to broken bonds induced by defects at the NW surface. Broken bonds at the surface, which communicate with the defect state of Si are critically altered when Ge is incorporated in Si NW. In addition, the number of defects could be significantly decreased in Si NWs by incorporating a surface passivated Al2O3 layer, which removes broken bonds, resulting in a proportional decrease in the resistivity of Si NWs with increasing strain. Moreover, the presence of a passivation layer dramatically increases fracture strain in NWs and a significant enhancement in mobility of more than 2.6 times was observed for a tensile strain of 5.7 %.
    No preview · Article · Oct 2015 · Nano Letters
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    ABSTRACT: A series of fluorophenyl and pyridine analogues of 1 and 2 were synthesized as ring-truncated deguelin surrogates and evaluated for their HIF-1α inhibition. Their structure-activity relationship was systematically investigated based on the variation of the linker B-region moiety. Among the inhibitors, compound 25 exhibited potent HIF-1α inhibition in a dose-dependent manner and significant antitumor activity in H1299 with less toxicity than deguelin. It also inhibited in vitro hypoxia-mediated angiogenic processes in HRMECs. The docking study indicates that 25 occupied the C-terminal ATP-binding pocket of HSP90 in a similar mode as 1, which implies that the anticancer and antiangiogenic activities of 25 are derived from HIF-1α destabilization by binding to the C-terminal ATP-binding site of hHSP90.
    No preview · Article · Oct 2015 · European Journal of Medicinal Chemistry
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    ABSTRACT: On page 6029, S.‐Y. Lee, S.‐Y. Lee, and co‐workers present cellulose nanofibril/multiwall carbon nanotube‐based hetero‐nanonet paper batteries as 1D material‐mediated cell architectures to enable ultrahigh energy density and shape versatility far beyond those achievable with conventional battery technologies. Benefiting from 3D bicontinuous electron/ion transport pathways and exceptional mechanical compliance, the hetero‐nanonet paper batteries provide unprecedented improvements in the electrochemical reaction kinetics, energy density, and origami foldability.
    Full-text · Article · Oct 2015 · Advanced Functional Materials
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    ABSTRACT: Intracellular amyloid beta (Aβ) has been implicated in neuronal cell death in Alzheimer's disease (AD). Intracellular Aβ also contributes to tight junction breakdown of retinal pigment epithelium (RPE) in age-related macular degeneration (AMD). Although Aβ is predominantly secreted from neuronal cells, the mechanism of Aβ transport into RPE remains to be fully elucidated. In this study, we demonstrated that intracellular Aβ was found concomitantly with the breakdown of tight junction in RPE after subretinal injection of Aβ into the mouse eye. We also presented evidence that receptor for advanced glycation end products (RAGE) contributed to endocytosis of Aβ in RPE. siRNA-mediated knockdown of RAGE prevented intracellular Aβ accumulation as well as subsequent tight junction breakdown in RPE. In addition, we found that RAGE-mediated p38 MAPK signaling contributed to endocytosis of Aβ. Blockade of RAGE/p38 MAPK signaling inhibited Aβ endocytosis, thereby preventing tight junction breakdown in RPE. These results implicate that intracellular Aβ contributes to the breakdown of tight junction in RPE via the RAGE/p38 MAPK-mediated endocytosis. Thus, we suggest that RAGE could be a potential therapeutic target for intracellular Aβ induced outer BRB breakdown in AMD.
    Full-text · Article · Sep 2015 · Oncotarget
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    ABSTRACT: We fabricated a carbon nanotube (CNT)/adhesive polydimethylsiloxane (aPDMS) composite-based dry electroencephalograph (EEG) electrode for capacitive measuring of EEG signals. As research related to brain-computer interface applications has advanced, the presence of hairs on a patient's scalp has continued to present an obstacle to recorder EEG signals using dry electrodes. The CNT/aPDMS electrode developed here is elastic, highly conductive, self-adhesive, and capable of making conformal contact with and attaching to a hairy scalp. Onto the conductive disk, hundreds of conductive pillars coated with Parylene C insulation layer were fabricated. A CNT/aPDMS layer was attached on the disk to transmit biosignals to the pillar. The top of disk was designed to be solderable, which enables the electrode to be connected with a variety of commercial EEG acquisition systems. The mechanical and electrical characteristics of the electrode were tested, and the performances of the electrodes were evaluated by recording EEGs, including alpha rhythms, auditory-evoked potentials, and steady-state visually-evoked potentials. The results revealed that the electrode provided a high signal-to-noise ratio with good tolerance for motion. Almost no leakage current was observed. Although preamplifiers with ultra-high input impedance have been essential for previous capacitive electrodes, the EEGs were recorded here by directly connecting a commercially available EEG acquisition system to the electrode to yield high quality signals comparable to those obtained using conventional wet electrodes.
    No preview · Article · Sep 2015 · IEEE transactions on bio-medical engineering
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    ABSTRACT: Objective: The influence of high-dose statin therapy on the serial stent healing process has not been fully investigated. Using optical coherence tomography, the effect of high-dose statin therapy on stent strut coverage was evaluated in drug-eluting stent-treated patients. Approach and results: Sixty patients were randomly assigned to 2 groups according to the statin dose (atorvastatin 40 mg as high-dose statin therapy [n=29] versus pravastatin 20 mg as low-dose statin therapy [n=31]). Serial optical coherence tomographic evaluation post procedure and at the 3-month and 12-month follow-ups was performed in 50 patients with 54 stents (23 atorvastatin-treated patients versus 27 pravastatin-treated patients). The percentage of uncovered struts was defined as the ratio of uncovered struts/total struts. The primary end point was the percentage of uncovered struts at the 12-month follow-up. The secondary end point was the percentage of uncovered struts at the 3-month follow-up and the comparative percentage change (Δ) of uncovered struts at the 3- and 12-month follow-ups between the different dose statin therapies. The percentage of uncovered struts was 7.4% (range, 4.3%-10.4%) in atorvastatin-treated patients versus 10.6% (range, 5.7%-22.6%) in pravastatin-treated patients at the 3-month follow-up (P=0.13) and 1.3% (0.3%-3.8%) versus 2.5% (0.9%-9.7%), respectively, at the 12-month follow-up (P=0.01). The percentage Δ of uncovered struts from 3 to 12 months of follow-up was -7.9±8.5% in atorvastatin-treated patients versus -9.3±12.5% in pravastatin-treated patients (P=0.67). Conclusions: This study suggested that high-dose statin therapy might provide a beneficial effect for the vascular healing process after drug-eluting stent implantation.
    No preview · Article · Sep 2015 · Arteriosclerosis Thrombosis and Vascular Biology
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    ABSTRACT: Forthcoming smart energy era is in strong pursuit of full-fledged rechargeable power sources with reliable electrochemical performances and shape versatility. Here, as a naturally abundant/environmentally friendly cellulose-mediated cell architecture strategy to address this challenging issue, a new class of hetero-nanonet (HN) paper batteries based on 1D building blocks of cellulose nanofibrils (CNFs)/multiwall carbon nanotubes (MWNTs) is demonstrated. The HN paper batteries consist of CNF/MWNT-intermingled heteronets embracing electrode active powders (CM electrodes) and microporous CNF separator membranes. The CNF/MWNT heteronet-mediated material/structural uniqueness enables the construction of 3D bicontinuous electron/ion transport pathways in the CM electrodes, thus facilitating electrochemical reaction kinetics. Furthermore, the metallic current collectors-free, CNF/MWNT heteronet architecture allows multiple stacking of CM electrodes in series, eventually leading to user-tailored, ultrathick (i.e., high-mass loading) electrodes far beyond those accessible with conventional battery technologies. Notably, the HN battery (multistacked LiNi0.5Mn1.5O4 (cathode)/multistacked graphite (anode)) provides exceptionally high-energy density (=226 Wh kg−1 per cell at 400 W kg−1 per cell), which surpasses the target value (=200 Wh kg−1 at 400 W kg−1) of long-range (=300 miles) electric vehicle batteries. In addition, the heteronet-enabled mechanical compliance of CM electrodes, in combination with readily deformable CNF separators, allows the fabrication of paper crane batteries via origami folding technique.
    Full-text · Article · Sep 2015 · Advanced Functional Materials
  • Sung Wook Park · Jin Hyoung Kim · Woo Jin Park · Jeong Hun Kim
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    ABSTRACT: The eye is a small and enclosed organ which makes it an ideal target for gene therapy. Recently various strategies have been applied to gene therapy in retinopathies using non-viral and viral gene delivery to the retina and retinal pigment epithelium (RPE). Subretinal injection is the best approach to deliver viral vectors directly to RPE cells. Before the clinical trial of a gene therapy, it is inevitable to validate the efficacy of the therapy in animal models of various retinopathies. Thus, subretinal injection in mice becomes a fundamental technique for an ocular gene therapy. In this protocol, we provide the easy and replicable technique for subretinal injection of viral vectors to experimental mice. This technique is modified from the intravitreal injection, which is widely used technique in ophthalmology clinics. The representative results of RPE/choroid/scleral complex flat-mount will help to understand the efficacy of this technique and adjust the volume and titer of viral vectors for the extent of gene transduction.
    No preview · Article · Aug 2015 · Journal of Visualized Experiments
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    ABSTRACT: Familial exudative vitreoretinopathy (FEVR) is a rare hereditary disorder characterized by the failure of peripheral retinal vascularization. The genes FZD4, LRP5, and TSPAN12 are known to be associated with the autosomal inheritance form of FEVR. In this study, we performed mutation screening for FZD4, LRP5, and TSPAN12 in patients with clinical diagnosis of FEVR. In patients with no mutation detected, sequencing analyses for ZNF408, a novel gene potentially related to FEVR, and two other genes related to retinal development, LGR4 and ATOH7, were performed. Mutational studies were done in 51 unrelated patients with diagnosis of FEVR during 2008 to 2012 at the Seoul National University Hospital. These patients were screened previously for NDP gene and confirmed to be negative for mutations. Diagnosis of FEVR was established by ophthalmic examinations. Data collected from medical records included sex, age at diagnosis, clinical presentation, and angiographic findings. In this study, we identified 3 known mutations, 10 novel variants with high possibility of pathogenicity, and a whole gene deletion in a total of 18 unrelated patients of 51, resulting in 35.3% of patients being genetically confirmed as having FEVR. Among the patients with pathogenic mutations detected, FZD4 mutations accounted for the largest proportion of autosomal inheritance FEVR cases (13/18 patients, 72.2%), followed by LRP5 (4/18 patients, 22.2%) and TSPAN12 (1/18 patients, 5.6%). No pathogenic mutations were identified in ZNF408, LGR4, and ATOH7. A significant difference in FEVR stage and visual acuity was observed according to the gene involved, showing that patients with FZD4 mutations had milder phenotype. Mutations of FZD4 accounted for the largest proportion, which could be directly applied to the testing strategy to start with screening for FZD4 mutations. Panel sequencing consisting of related genes would be an alternative choice for the diagnosis of FEVR. Also, genotype-phenotype correlation suggested in this study could be helpful in genetic counseling of the probands and their family members as well.
    No preview · Article · Aug 2015 · Investigative ophthalmology & visual science

  • No preview · Article · Aug 2015
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    ABSTRACT: Anti-vascular endothelial growth factor (VEGF) agents are the mainstay treatment for various angiogenesis-related retinal diseases. Currently, bevacizumab, a recombinant humanized anti-VEGF antibody, is trailed in retinopathy of prematurity, a vasoproliferative retinal disorder in premature infants. However, the risks of systemic complications after intravitreal injection of anti-VEGF antibody in infants are not well understood. In this study, we show that intravitreally injected anti-VEGF antibody is transported into the systemic circulation into the periphery where it reduces brown fat in neonatal C57BL/6 mice. A considerable amount of anti-VEGF antibody was detected in serum after intravitreal injection. Furthermore, in interscapular brown adipose tissue, we found lipid droplet accumulation, decreased VEGF levels, loss of vascular network, and decreased expression of mitochondria-related genes, Ppargc1a and Ucp1, all of which are characteristics of “whitening” of brown fat. With increasing age and body weight, brown fat restored its morphology and vascularity. Our results show that there is a transient, but significant impact of intravitreally administered anti-VEGF antibody on brown adipose tissue in neonatal mice. We suggest that more attention should be focused on the metabolic and developmental significance of brown adipose tissue in bevacizumab treated retinopathy of prematurity infants.
    No preview · Article · Jul 2015 · PLoS ONE
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    ABSTRACT: R-(-)-β-O-methylsynephrine (OMe-Syn) is a naturally occurring small molecule that was identified in a previous screen as an inhibitor of angiogenesis. In this study, we conducted two animal model experiments to investigate the in vivo antiangiogenic activity of OMe-Syn. OMe-Syn significantly inhibited angiogenesis in a transgenic zebrafish model as well as in a mouse retinopathy model. To elucidate the underlying mechanisms responsible for the antiangiogenic activity of OMe-Syn, we used phage display cloning to isolate potential OMe-Syn binding proteins from human cDNA libraries and identified nucleoporin 153 kDa (NUP153) as a primary binding partner of OMe-Syn. OMe-Syn competitively inhibited mRNA binding to the RNA-binding domain of NUP153. Furthermore, depletion of NUP153 in human cells or zebrafish embryos led to an inhibition of angiogenesis, in a manner similar to that seen in response to OMe-Syn treatment. These data suggest that OMe-Syn is a promising candidate for the development of a novel antiangiogenic agent and that inhibition of NUP153 is possibly responsible for the antiangiogenic activity of OMe-Syn.
    Full-text · Article · Jul 2015 · International journal of biological sciences
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    ABSTRACT: Pericytes enveloping the endothelium play an important role in the physiology and pathology of microvessels, especially in vessel maturation and stabilization. However, our understanding of fundamental pericyte biology is limited by the lack of a robust in vitro model system that allows researchers to evaluate the interactions among multiple cell types in perfusable blood vessels. The present work describes a microfluidic platform that can be used to investigate interactions between pericytes and endothelial cells (ECs) during the sprouting, growth, and maturation steps of neovessel formation. A mixture of ECs and pericytes was attached to the side of a pre-patterned three dimensional fibrin matrix and allowed to sprout across the matrix. The effects of intact coverage and EC maturation by the pericytes on the perfused EC network were confirmed using a confocal microscope. Compared with EC monoculture conditions, EC-pericyte co-cultured vessels showed a significant reduction in diameter, increased numbers of junctions and branches and decreased permeability. In response to biochemical factors, ECs and pericytes in the platform showed the similar features with previous reports from in vivo experiments, thus reflect various pathophysiological conditions of in vivo microvessels. Taken together, these results support the physiological relevancy of our three-dimensional microfluidic culture system but also that the system can be used to screen drug effect on EC-pericyte biology.
    Full-text · Article · Jul 2015 · PLoS ONE
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    ABSTRACT: Carbon nanotubes (CNTs) have an important role in nanotechnology due to their unique properties, retaining the inherent material flexibility, superior strength, and electrical conductivity, unless the bottleneck of CNTs to persist aggregated structure is overcome. Here, we report on the highly enhanced mechanical and electrical properties of the CNT-chitosan nanocomposites through homogeneous dispersion of CNTs into chitosan solution using a high-pressure homogenizer. The optimal condition is a 50% w/w in chitosan-CNT film, providing about 7 nm thickness of homogenous chitosan layer on CNTs, a good tensile strength of 51 MPa, high electrical conductivity under 16 ohm/sq and a stable bending and folding performance. This CNT-chitosan nanocomposite with highly enhanced properties is an amenable material to fabricate structures of various shapes like films, sensors, and circuits and also enables a simple and cost-effective approach to improve the performance of a device that presents the first flexible and soft electric circuits yet reported using only CNT-chitosan as the conductor.
    No preview · Article · Jun 2015 · Langmuir
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    ABSTRACT: Vascular integrity is important in maintaining homeostasis of brain microenvironments. In various brain diseases including Alzheimer’s disease, stroke, and multiple sclerosis, increased paracellular permeability due to breakdown of blood-brain barrier is linked with initiation and progression of pathological conditions. We developed a capacitance sensor array to monitor dielectric responses of cerebral endothelial cell monolayer, which could be utilized to evaluate the integrity of brain microvasculature. Our system measured real-time capacitance values which demonstrated frequency- and time-dependent variations. With the measurement of capacitance at the frequency of 100 Hz, we could differentiate the effects of vascular endothelial growth factor (VEGF), a representative permeability-inducing factor, on endothelial cells and quantitatively analyse the normalized values. Interestingly, we showed differential capacitance values according to the status of endothelial cell monolayer, confluent or sparse, evidencing that the integrity of monolayer was associated with capacitance values. Another notable feature was that we could evaluate the expression of molecules in samples in our system with the reference of real-time capacitance values. We suggest that this dielectric spectroscopy system could be successfully implanted as a novel in vitro assay in the investigation of the roles of paracellular permeability in various brain diseases.
    No preview · Article · Jun 2015 · Scientific Reports

  • No preview · Conference Paper · Jun 2015
  • Dong Hyun Jo · Jin Hyoung Kim · Tae Geol Lee · Jeong Hun Kim
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    ABSTRACT: Nanoparticles can be valuable therapeutic options to overcome physical barriers to reach central nervous system. Systemically administered nanoparticles can pass through blood-neural barriers; whereas, locally injected nanoparticles directly reach neuronal and perineuronal cells. In this review, we highlight the importance of size, surface charge, and shape of nanoparticles in determining therapeutic effects on brain and retinal diseases. These features affect overall processes of delivery of nanoparticles: in vivo stability in blood and other body fluids, clearance via mononuclear phagocyte system, attachment with target cells, and penetration into target cells. Furthermore, they are also determinants of nano-bio interfaces: they determine corona formation with proteins in body fluids. Taken together, we emphasizes the importance of considerations on characteristics of nanoparticles more suitable for the treatment of brain and retinal diseases in the development of nanoparticle-based therapeutics. Copyright © 2015. Published by Elsevier Inc.
    No preview · Article · May 2015 · Nanomedicine: nanotechnology, biology, and medicine

Publication Stats

4k Citations
599.03 Total Impact Points

Institutions

  • 2015
    • Ulsan National Institute of Science and Technology
      Ulsan, Ulsan, South Korea
  • 2012-2015
    • Hanyang University
      • Department of Electronic and Electrical Engineering
      Sŏul, Seoul, South Korea
    • University of Michigan
      • Life Sciences Institute
      Ann Arbor, MI, United States
  • 2006-2015
    • Korea University
      • • Department of Biomedical Engineering
      • • Department of Computer Science and Radio Communications Engineering
      • • Department of Electrical Engineering
      Sŏul, Seoul, South Korea
    • University of Auckland
      • Liggins Institute
      Окленд, Auckland, New Zealand
  • 2005-2015
    • Yonsei University
      • • Department of Biotechnology
      • • Department of Biochemistry
      Sŏul, Seoul, South Korea
  • 2002-2015
    • Seoul National University
      • • Department of Ophthalmology
      • • College of Pharmacy
      Sŏul, Seoul, South Korea
    • Seoul National University Hospital
      • Department of Ophthalmology
      Sŏul, Seoul, South Korea
  • 2014
    • MEDIPOST Biomedical Research Institute
      Sŏul, Seoul, South Korea
  • 2012-2014
    • Chonnam National University
      • Department of Cardiology
      Gwangju, Gwangju, South Korea
  • 2013
    • Yonsei University Hospital
      • Department of Internal Medicine
      Seoul, Seoul, South Korea
    • Asan Medical Center
      Sŏul, Seoul, South Korea
  • 2010
    • University of California, Los Angeles
      • Department of Computer Science
      Los Ángeles, California, United States
    • Chonnam National University Hospital
      Sŏul, Seoul, South Korea
  • 2009
    • Catholic Kwandong University
      Gangneung, Gangwon-do, South Korea
  • 2008
    • Chosun University
      Gwangju, Gwangju, South Korea
    • Korea Research Institute of Standards and Science
      Daiden, Daejeon, South Korea
  • 2007
    • Ewha Womans University
      Sŏul, Seoul, South Korea