Jun Young Lee

Korea University, Sŏul, Seoul, South Korea

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Publications (299)628.57 Total impact

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    ABSTRACT: A hybrid structure comprising organic dye molecules (e.g., rhodamine 6G) and graphene was developed for the realization of high-performance optoelectronic devices. The fabricated photodetector offered a broad spectral photo-response across wavelengths in the infrared, visible, and ultraviolet regions, as well as a high responsivity (∼460 A/W at illumination power of 1 μW). The photocurrent generated in the hybrid photodetector (∼mA) was much higher than that generated in a pristine graphene photodetector (<μA). The performance of the dye-sensitized photodetector relied on enhanced photoabsorption and the implementation of a photocurrent gain arising from the photo-excited charges.
    Carbon 07/2015; 88. DOI:10.1016/j.carbon.2015.02.071 · 6.16 Impact Factor
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    ABSTRACT: Prior intracerebral haemorrhage and cerebral microbleeds may increase the risk of haemorrhagic stroke. However, the optimal long-term antiplatelet therapy and lipid management in these patients remain unclear. PreventIon of CArdiovascular events in iSchemic Stroke patients with high risk of cerebral hemOrrhage was designed to compare cilostazol and aspirin and to assess the effect of adding probucol, a lipid-lowering and anti-oxidative agent, in patients at high risk of haemorrhagic stroke. The projected sample size is 1600 patients with at least 12 months of follow-up. PreventIon of CArdiovascular events in iSchemic Stroke patients with high risk of cerebral hemOrrhage is a randomized trial involving 67 institutes from 3 countries. Patients with non-cardioembolic ischemic stroke or transient ischemic attack within 180 days and with prior intracerebral haemorrhage or multiple cerebral microbleeds on gradient echo imaging are eligible. Enrolled patients are simultaneously randomized in a 2 × 2 factorial design: double-blind for cilostazol 200 mg/day vs. aspirin 100 mg/day, and an open-label, blind end-point evaluation for probucol 500 mg/day vs. non-probucol. The co-primary end-points are the safety end-point of haemorrhagic stroke and the efficacy end-point of a composite of stroke, myocardial infarction, or vascular death. Time-to-event will be analyzed separately for each intervention: superiority testing for the safety of cilostazol over aspirin as well as the efficacy of probucol over non-probucol, and non-inferiority testing for the efficacy of cilostazol to aspirin. PreventIon of CArdiovascular events in iSchemic Stroke patients with high risk of cerebral hemOrrhage is the largest secondary stroke prevention trial for informing antiplatelet therapy and lipid management in patients at high risk of haemorrhagic stroke. © 2015 World Stroke Organization.
    International Journal of Stroke 07/2015; DOI:10.1111/ijs.12519 · 4.03 Impact Factor
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    ABSTRACT: Copeptin has been considered as a useful marker for diagnosis and prediction of prognosis in heart diseases. However, copeptin has not been investigated sufficiently in hemodialysis patients. This study aimed to investigate the general features of copeptin in hemodialysis and to examine the usefulness of copeptin in hemodialysis patients with left ventricular dysfunction (LV dysfunction). This study included 41 patients on regular hemodialysis. Routine laboratory data and peptides such as the N-terminal of the prohormone brain natriuretic peptide and copeptin were measured on the day of hemodialysis. Body fluid volume was estimated by bioimpedance spectroscopy, and the E/Ea ratio was estimated by echocardiography. Copeptin increased to 171.4 pg/mL before hemodialysis. The copeptin had a positive correlation with pre-dialysis body fluid volume (r=0.314; p=0.04). The copeptin level decreased along with body fluid volume and plasma osmolality during hemodialysis. The copeptin increased in the patients with LV dysfunction more than in those with normal LV function (218.7 pg/mL vs. 77.6 pg/mL; p=0.01). Receiver operating characteristic curve analysis showed that copeptin had a diagnostic value in the hemodialysis patients with LV dysfunction (area under curve 0.737; p=0.02) and that the cut-off value was 125.48 pg/mL (sensitivity 0.7, specificity 0.8, positive predictive value 0.9, negative predictive value 0.6). Copeptin increases in hemodialysis patients and is higher in patients with LV dysfunction. We believe that copeptin can be a useful marker for the diagnosis of LV dysfunction in hemodialysis patients.
    Yonsei medical journal 07/2015; 56(4):976-980. DOI:10.3349/ymj.2015.56.4.976 · 1.26 Impact Factor
  • The Journal of Dermatology 06/2015; DOI:10.1111/1346-8138.13011 · 2.35 Impact Factor
  • Pediatric Dermatology 05/2015; 32(3). DOI:10.1111/pde.12397 · 1.52 Impact Factor
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    03/2015; 51(2). DOI:10.1016/j.jdcr.2015.02.003
  • 03/2015; 25(3):169-175. DOI:10.5050/KSNVE.2015.25.3.169
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    ABSTRACT: We devised a simple transparent metal oxide thin film transistor architecture composed of only two component materials, an amorphous metal oxide and ion gel gate dielectric, which could be entirely assembled using room temperature processes on a plastic substrate. The geometry cleverly takes advantages of the unique characteristics of the two components. An oxide layer is metallized upon exposure to plasma, leading to the formation of a monolithic source-channel-drain oxide layer, and the ion gel gate dielectric is used to gate the transistor channel effectively at low voltages through a coplanar gate. We confirmed that the method is generally applicable to a variety of sol-gel processed amorphous metal oxides, including indium oxide, indium zinc oxide, and indium gallium zinc oxide. An inverter NOT logic device was assembled using the resulting devices as a proof of concept demonstration of the applicability of the devices to logic circuits. The favorable characteristics of these devices, including i) the simplicity of the device structure with only two components, ii) the benign fabrication processes at room temperature, iii) the low-voltage operation under 2 V, and iv) the excellent and stable electrical performances, together support the application of these devices to low-cost portable gadgets, i.e., cheap electronics.
    ACS Nano 03/2015; 9(4). DOI:10.1021/acsnano.5b00700 · 12.03 Impact Factor
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    ABSTRACT: The influence of processing conditions, such as ink concentration and coating method, on the thermoelectric properties of SWCNT/P3HT nanocomposite films was investigated systematically. Using simple wire-bar-coating, SWCNT/P3HT nanocomposite films with high thermoelectric performance could be obtained without additional P3HT doping. The wire-bar-coated SWCNT/P3HT nanocomposite films exhibited power factors of up to 105 µW m-1K-2 at room temperature. The SWCNT bundles with diameters in the range of 6 - 23 nm formed an interconnected network in the wire-bar-coated nanocomposite films. Network formation in these nanocomposite films was expected to be strongly related to the development of electrical pathways due to inter-SWCNT bundle connections. This study suggests that the thermoelectric performance of SWCNT/P3HT nanocomposite films could be optimized by controlling their processing conditions and morphology.
    ACS Applied Materials & Interfaces 03/2015; 7(12). DOI:10.1021/acsami.5b00626 · 5.90 Impact Factor
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    Annals of Dermatology 02/2015; 27(1):90-2. DOI:10.5021/ad.2015.27.1.90 · 0.95 Impact Factor
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    ABSTRACT: Patients with atopic dermatitis (AD) should be relatively well informed about the disorder to control their condition and prevent flare-ups. Thus far, there is no accurate information about the disease awareness levels and therapeutic behavior of AD patients. To collect data on patients' knowledge about AD and their behavior in relation to seeking information about the disease and its treatment. We performed a questionnaire survey on the disease awareness and self-management behavior of AD patients. A total of 313 patients and parents of patients with AD who had visited the The Catholic University of Korea, Catholic Medical Center between November 2011 and October 2012 were recruited. We compared the percentage of correct answers from all collected questionnaires according to the demographic and disease characteristics of the patients. Although dermatologists were the most frequent disease information sources and treatment providers for the AD patients, a significant proportion of participants obtained information from the Internet, which carries a huge amount of false medical information. A considerable number of participants perceived false online information as genuine, especially concerning complementary and alternative medicine treatments of AD, and the adverse effects of steroids. Some questions on AD knowledge had significantly different answers according to sex, marriage status, educational level, type of residence and living area, disease duration, disease severity, and treatment history with dermatologists. Dermatologists should pay more attention to correcting the common misunderstandings about AD to reduce unnecessary social/economic losses and improve treatment compliance.
    Annals of Dermatology 02/2015; 27(1):40-7. DOI:10.5021/ad.2015.27.1.40 · 0.95 Impact Factor
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    ABSTRACT: We investigated the heterojunction effects of perylene tetracarboxylic diimide (PTCDI) derivatives on the pentacene-based field-effect transistors (FETs). Three PTCDI derivatives with different substituents were deposited onto pentacene layers, and served as charge transfer dopants. The deposited PTCDI layer, which had a nominal thickness of a few layers, formed discontinuous patches on the pentacene layers, and dramatically enhanced the hole mobility in the pentacene FET. Among the three PTCDI molecules tested, the octyl substitut-ed PTCDI, PTCDI-C8, provided the most efficient hole doping characteristics (p-type) relative to the fluoro-phenyl substituted PTCDIs, 4-FPEPTC and 2,4-FPEPTC. The organic heterojunction and doping characteristics were systematically investigated using atomic force microscopy (AFM), 2D grazing incidence X-ray diffraction (2D GIXD) studies, and ultraviolet photoelectron spectroscopy (UPS). PTCDI-C8, bearing octyl substituents, grew laterally on the pentacene layer (2D growth), whereas 2,4-FPEPTC, with fluorophenyl substituents, un-derwent 3D growth. The different growth modes resulted in different contact areas and relative orientations between the pentacene and PTCDI molecules, which significantly affected the doping efficiency of the deposited adlayer. The differences between the growth modes and the thin-film microstructures in the different PTCDI patches were attributed to mismatch between the surface energies of the patches and the underlying pentacene layer. The film morphology-dependent doping effects observed here offer practical guidelines for achieving more effective charge transfer doping in thin film transistors.
    ACS Applied Materials & Interfaces 01/2015; 7(3). DOI:10.1021/am507854s · 5.90 Impact Factor
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    ABSTRACT: The major issues of self-assembled nanoparticles as drug carriers for cancer therapy include biostability and tumor-targetability because the premature drug release from and nonspecific accumulation of the drug-loaded nanoparticles may cause undesirable toxicity to normal organs and lower therapeutic efficacy. In this study, we developed robust and tumor-targeted nanocarriers based on an amphiphilic hyaluronic acid (HA)-polycaprolactone (PCL) block copolymer, in which the HA shell was cross-linked via a bioreducible disulfide linkage. Doxorubicin (DOX), chosen as a model anticancer drug, was effectively encapsulated into the nanoparticles with high drug loading efficiency. The DOX-loaded bioreducible HA nanoparticles (DOX-HA-ss-NPs) greatly retarded the drug release under physiological conditions (pH 7.4), whereas the drug release rate was markedly enhanced in the presence of glutathione, a thiol-containing tripeptide capable of reducing disulfide bonds in the cytoplasm. Furthermore, DOX-HA-ss-NPs could effectively deliver the DOX into the nuclei of SCC7 cells in vitro as well as to tumors in vivo after systemic administration into SCC7 tumor-bearing mice, resulting in improved antitumor efficacy in tumor-bearing mice. Overall, it was demonstrated that bioreducible shell-cross-linked nanoparticles could be used as a potential carrier for cancer therapy.
    Biomacromolecules 01/2015; 16(2). DOI:10.1021/bm5017755 · 5.79 Impact Factor
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    ABSTRACT: The Oxford classification of immunoglobulin A nephropathy (IgAN) is a pathology-based prognostic classification system. However, further study is needed to determine its validity. We studied the relationships between the Oxford classification and established prognostic factors and renal survival. We also examined associations between electron microscopy findings and these parameters.
    01/2015; 88(4):397. DOI:10.3904/kjm.2015.88.4.397
  • Organic Electronics 12/2014; 15(12):3439–3444. DOI:10.1016/j.orgel.2014.09.034 · 3.68 Impact Factor
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    ABSTRACT: Although silver bromide has recently drawn considerable attention due to its high photocatalytic activity, it tends to form agglomerated metallic silver under the irradiation of visible light. Therefore, photocatalytic activity decreases with time and cannot be applied for repeated uses. To overcome this limitation, in the present work, we complexed AgBr with nitrogen doped (N-doped) and amine functionalized reduced graphene oxide (GN). N-doped and/or amine functionalized graphene shows intrinsically good catalytic activity. Besides, amine groups can undergo complexation with silver ions to suppress its reduction to metallic Ag. As a result, this complexed catalysts show excellent photocatalytic activity for the degradation of methylene blue (MB) dye under the irradiation of visible light. Photocatalytic degradation of MB shows that the catalytic activity is optimized at a condition of 0.5 wt% GN, under which ~ 99 % of MB was degraded only after 50 min of visible light irradiation. Notably, the complexed catalyst is quiet stable and retained almost full of its catalytic activity even after greater than ten repeated cycles. Moreover, the catalyst can also efficiently decompose 2-chlorophenol, a colorless organic contaminant, under visible light exposure. Detailed experimental investigation reveals that hydroxyl (·OH) radicals play an important role for dye degradation reactions. A relevant mechanism for dye degradation has also been proposed.
    ACS Applied Materials & Interfaces 11/2014; DOI:10.1021/am5051422 · 5.90 Impact Factor
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    ABSTRACT: It is extremely important to provide the substrate of the flexible OLED with transparent and flexible moisture barrier property since the organic functional layers and metal electrodes are highly sensitive to water vapor. Solution processible moisture barrier may be a potential candidate to achieve low cost, high productivity and large area moisture barrier. In this study, we fabricated an organic–inorganic hybrid moisture barrier thin film by the condensation reaction between poly(melamine-co-formaldehyde) (PMF) and tetraethyl orthosilicate (TEOS) using sol–gel method. It was expected that PMF and silicone oxide provided the thin film with mechanical flexibility and moisture barrier property, respectively. It was confirmed that very dense hybrid monolayer and multi-layer films with very smooth surface and high optical transmittance were successfully fabricated using the sol–gel process. Moisture barrier property was determined by water vapor transmission rate (WVTR) measured by Ca-test at 85 °C and 85% RH. WVTR of the bare poly(ethylene naphthalate) (PEN, 150 μm) film was found to be about 17 g/m2/day, while the PEN film coated with the hybrid film showed the lower WVTR value of 4.5 g/m2/day. The WVTR value at 85 °C and 85% RH corresponds to the value in the range of 10–2–10–3 g/m2/day under ambient condition, confirming the efficient moisture barrier property of the hybrid layers.
    Science of Advanced Materials 11/2014; 6(11). DOI:10.1166/sam.2014.2212 · 2.91 Impact Factor
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    ABSTRACT: Bioreducible carboxymethyl dextran (CMD) derivatives are synthesized by the chemical modification of CMD with lithocholic acid (LCA) through a disulfide linkage. The hydrophobic nature of LCA allows the conjugates (CMD-SS-LCAs) to form self-assembled nanoparticles in aqueous conditions. Depending on the degree of LCA substitution, the particle diameters range from 163 to 242 nm. Doxorubicin (DOX), chosen as a model anticancer drug, is effectively encapsulated into the nanoparticles with high loading efficiency (>70%). In vitro optical imaging tests reveal that the fluorescence signal of DOX quenched in the bioreducible nanoparticles is highly recovered in the presence of glutathione (GSH), a tripeptide capable of reducing disulfide bonds in the intracellular compartments. Bioreducible nanoparticles rapidly release DOX when they are incubated with 10 mm GSH, whereas the drug release is greatly retarded in physiological buffer (pH 7.4). DOX-loaded bioreducible nanoparticles exhibit higher toxicity to SCC7 cancer cells than DOX-loaded nanoparticles without the disulfide bond. Confocal laser scanning microscopy observation demonstrate that bioreducible nanoparticles can effectively deliver DOX into the nuclei of SCC7 cells. In vivo biodistribution study indicates that Cy5.5-labeled CMD-SS-LCAs selectively accumulate at tumor sites after systemic administration into tumor-bearing mice. Notably, DOX-loaded bioreducible nanoparticles exhibit higher antitumor efficacy than reduction-insensitive control nanoparticles. Overall, it is evident that bioreducible CMD-SS-LCA nanoparticles are useful as a drug carrier for cancer therapy.
    Advanced Healthcare Materials 11/2014; 3(11). DOI:10.1002/adhm.201300691 · 4.88 Impact Factor
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    ABSTRACT: Bioreducible nanoparticles, composed of hydrophilic carboxymethyl dextran and hydrophobic bile acid, are developed by J. H. Park and co-workers on page 1829 for the site-specific delivery of poorly water-soluble anticancer drugs at the tumor microenvironment.
    Advanced Healthcare Materials 11/2014; 3(11). DOI:10.1002/adhm.201470057 · 4.88 Impact Factor
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    ABSTRACT: Objective To investigate the natural course of depressive symptoms among community-dwelling elderly over 5 years. Rates and correlates of the incidence and the persistence of late-life depression were examined.MethodsA total of 701 elderly people 65 years of age or older without dementia at baseline were included in this study. The association between categorically defined late-life depression (score of ≥8 on the Korean version of the Geriatric Depression Scale-Short Form) and possible lifestyle and clinical risk factors, including physical activity assessed with a modified Korean version of the International Physical Activity Questionnaire (IPAQ) and transformed into weekly Metabolic Equivalent Task (MET) values, was longitudinally investigated using multiple logistic regression analyses. Adjustment was done with sociodemographic variables, chronic medical illnesses, and cognitive dysfunction.ResultsDuring the 5-year follow-up, 74 (26.5%) of the non-depressed elderly developed depression, whereas 30 (49.2%) of the depressed elderly experienced persistent depression. Above-moderate baseline physical activity was independently associated with decreased incidence and persistence rates of late-life depression (adjusted odds ratio (AOR) = 0.44, 95% confidence interval (CI) = 0.22–0.85; AOR = 0.17, 95% CI = 0.03–0.92, respectively), whereas mild physical activity was not. Conversely, poorer executive function also predicted 5-year incident depression (AOR = 0.93, 95% CI = 0.89–0.98) but not persistent depression.Conclusion This study suggests that a minimum of moderate physical activity is related to both emergent and persistent depression in elderly individuals. Research with an extended follow-up period and a shorter inter-assessment interval is needed to confirm this result. Copyright © 2014 John Wiley & Sons, Ltd.
    International Journal of Geriatric Psychiatry 11/2014; 30(7). DOI:10.1002/gps.4244 · 3.09 Impact Factor

Publication Stats

2k Citations
628.57 Total Impact Points

Institutions

  • 2015
    • Korea University
      • College of Medicine
      Sŏul, Seoul, South Korea
  • 2001–2015
    • Catholic University of Korea
      • Department of Dermatology
      Sŏul, Seoul, South Korea
  • 2000–2015
    • Sungkyunkwan University
      • • Department of Chemical Engineering
      • • Institute of Science and Technology Law
      • • Department of Polymer Science and Engineering
      Sŏul, Seoul, South Korea
  • 2014
    • Gyeongju University
      Gyeongju, Gyeongsangbuk-do, South Korea
    • Soongsil University
      • Department of Chemical Engineering
      Sŏul, Seoul, South Korea
  • 2008–2014
    • Seoul National University
      • • College of Medicine
      • • Department of Neuropsychiatry
      Sŏul, Seoul, South Korea
    • Kyung Hee University
      • Pharmaceutical Science Division
      Sŏul, Seoul, South Korea
  • 2004–2014
    • Chosun University
      • College of Medicine
      Gwangju, Gwangju, South Korea
  • 2000–2014
    • Yonsei University
      • • Department of Materials Science and Engineering
      • • Department of Chemical and Biomolecular Engineering
      Sŏul, Seoul, South Korea
  • 2013
    • International St. Mary's Hospitals
      Chemulpo, Incheon, South Korea
    • Kookmin University
      • Graduate School of Automotive Engineering
      Sŏul, Seoul, South Korea
  • 2012–2013
    • Yonsei University Hospital
      • Department of Internal Medicine
      Seoul, Seoul, South Korea
    • Dongguk University
      • College of Science and Technology
      Sŏul, Seoul, South Korea
  • 2011–2012
    • Chonbuk National University Hospital
      Sŏul, Seoul, South Korea
    • Fukushima Medical University
      • Department of Gastroenterology and Rheumatology
      Hukusima, Fukushima, Japan
    • Seoul Medical Center
      Sŏul, Seoul, South Korea
    • Wonkwang University
      • Department of Medicine
      Riri, North Jeolla, South Korea
    • University of Seoul
      Sŏul, Seoul, South Korea
  • 2009–2012
    • Wonkwang University School of Medicine and Hospital
      Riri, North Jeolla, South Korea
    • Korea Institute of Industrial Technology
      Anzan, Gyeonggi Province, South Korea
  • 2001–2012
    • Korea Advanced Institute of Science and Technology
      • • Department of Chemistry
      • • Department of Chemical and Biomolecular Engineering
      Sŏul, Seoul, South Korea
  • 2007–2011
    • Electronics and Telecommunications Research Institute
      Sŏul, Seoul, South Korea
    • Soonchunhyang University
      • College of Medicine
      Onyang, South Chungcheong, South Korea
  • 2010
    • Yeungnam University
      • Division of Internal Medicine
      Gyeongsan, Gyeongsangbuk-do, South Korea
  • 2006
    • Keimyung University
      • Department of Chemical System Engineering
      Sŏul, Seoul, South Korea
  • 2005–2006
    • Sejong University
      • Department of Physics
      Sŏul, Seoul, South Korea
  • 1999–2003
    • University of Suwon
      Suigen, Gyeonggi Province, South Korea
  • 2002
    • Catholic University of Daegu
      • Department of Food Science and Nutrition
      Kayō, Gyeongsangbuk-do, South Korea
    • University of Ulsan
      • College of Medicine
      Urusan, Ulsan, South Korea
  • 1997
    • Korea Institute of Science and Technology
      • Electronic Materials Research Center
      Sŏul, Seoul, South Korea