Kyung Min Kim

Korea University, Sŏul, Seoul, South Korea

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Publications (84)218.11 Total impact

  • Organic Electronics 12/2014; 15(12):3538–3545. · 3.68 Impact Factor
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    ABSTRACT: In this article, we described a roll-to-roll (R2R) deposition processed amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs), depending on the source/drain (S/D) offset length from 10 to 80μm equally at S/D each side. It was fabricated at a maximum temperature under 250°C. Increasing length of S/D offset makes the device performance be lowered, but additional process at the offset region can minimize this problem. We demonstrated that the R2R deposition processed TFTs exhibited competitive device characteristics with large S/D offset (∼80μm), including an averaged field-effect mobility of 3.06cm2/Vs, an on-to-off current ratio of ∼107, a threshold voltage of 1.33V, and a subthreshold gate swing of 0.54V/dec.
    SID Symposium Digest of Technical Papers. 06/2014; 45(1).
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    ABSTRACT: Shear stress activates cellular signaling involved in cellular proliferation, differentiation, and migration. However, the mechanisms of mesenchymal stem cell (MSC) differentiation under interstitial flow are not fully understood. Here, we show the increased osteogenic differentiation of MSCs under exposure to constant, extremely low shear stress created by osmotic pressure-induced flow in a microfluidic chip. The interstitial level of shear stress in the proposed microfluidic system stimulated nuclear localization of TAZ (transcriptional coactivator with PDZ-binding motif), a transcriptional modulator of MSCs, activated TAZ target genes such as CTGF and Cyr61, and induced osteogenic differentiation. TAZ-depleted cells showed defects in shear stress-induced osteogenic differentiation. In shear stress induced cellular signaling, Rho signaling pathway was important forthe nuclear localization of TAZ. Taken together, these results suggest that TAZ is an important mediator of interstitial flow-driven shear stress signaling in osteoblast differentiation of MSCs.
    PLoS ONE 03/2014; 9(3):e92427. · 3.53 Impact Factor
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    ABSTRACT: Cardiovascular disease is an important cause of death in patients with end-stage renal disease. Although coronary artery bypass graft (CABG) surgery and drug-eluting stent (DES) implantation have been compared in chronic hemodialysis patients, the results are unclear. The study population consisted of chronic hemodialysis patients (dialysis duration >6 months) with coronary artery disease who underwent DES implantation or CABG at the Asan Medical Center (Seoul, Korea) between January 1, 2003, and February 28, 2006. We followed them until December, 2012. The mean follow-up was 50.91 ± 31.86 months for DES patients and 50.63 ± 36.43 months for CABG patients. Primary end points were major adverse cardiac and cerebral events (MACCE). Propensity-score matching was used to reduce selection bias and variable characteristics. Of 87 chronic hemodialysis patients with coronary artery disease, 44 underwent DES implantation and 43 underwent CABG surgery. Multivessel disease patients were 70.45 % in the DES group and 95.35 % in the CABG group. After propensity score adjustment, the MACCE-free survival was significantly higher in the CABG group than in the DES group (HR 3.265; 95 % CI 1.357-7.858; p = 0.008), but overall survival did not differ between the groups (HR 0.968; 95 % CI 0.267-3.507; p = 0.960). We found that, compared with DES, CABG showed significantly better MACCE-free survival in chronic hemodialysis patients.
    Journal of nephrology 02/2014; 27(1):87-93. · 2.00 Impact Factor
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    ABSTRACT: Increased epicardial adipose tissue (EAT) may be closely associated with the development of metabolic abnormalities. We investigated whether EAT predicts the incident metabolic syndrome in a community-based, middle-aged population. The study subjects were comprised of 354 adults (134 men and 220 women) aged 40 to 70 yr without metabolic syndrome. Baseline EAT thickness, measured by echocardiography, was compared between subjects who developed new-onset metabolic syndrome at follow-up survey and those who did not. After an average of 2.2 yr of follow-up, 32 men (23.9%) and 37 women (16.8%) developed metabolic syndrome. Median EAT thickness at baseline was significantly higher in male subjects who developed metabolic syndrome than those who did not (1.52 mm vs 2.37 mm, P<0.001). The highest quartile of EAT thickness (≥2.55 mm) was associated with increased risk of progression to metabolic syndrome (Odds ratio [OR], 3.09; 95% confidence interval [CI], 1.11-8.66) after adjustment for age, smoking, alcohol intake, regular exercise, total energy intake, high sensitive C-reactive protein and homeostasis model assessment of insulin resistance in men. A significant association of EAT with incident metabolic syndrome was not seen in women (OR, 1.25; 95% CI, 0.54-2.90). In conclusion, increased EAT thickness is an independent predictor for incident metabolic syndrome in men.
    Journal of Korean medical science 12/2013; 28(12):1762-7. · 0.84 Impact Factor
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    ABSTRACT: The aim of our study was to compare the values of brachial-ankle pulse wave velocity (baPWV) measured with two different non-invasive methods as predictors of coronary artery disease (CAD) in patients who had undergone coronary angiography. From 6373 patients who visited our laboratory for non-invasive procedures, we enrolled 965 consecutive patients undergoing coronary angiography. Data for baPWV and peripheral augmentation index (pAI) were recorded. CAD was defined as greater than 50% stenosis of a major epicardial artery in a coronary angiogram. In addition, the severity of CAD was classified as: none/minimal or 1-, 2-, or 3-vessel disease, based on previous or current angiographic findings. Among 965 subjects, the mean age was 63.7±11.6 years, and 58.2% were male. Compared with subjects without CAD disease, those with CAD showed higher values of baPWV (16.6±3.5 m/sec vs. 15.9±3.4 m/sec, p<0.001), and lower values of pAI (73.5±15.9% vs. 76.0±15.7%, p=0.01). When the severity of CAD was expressed as none/minimal or 1-, 2-, or 3-vessel disease, there was a significant association between the extent of CAD and baPWV (p<0.001). In univariate analysis, high PWV and low pAI were associated with an increased prevalence of CAD (p<0.001). Increased baPWV and decreased pAI were associated with the presence of CAD in the elderly.
    Korean Circulation Journal 12/2013; 43(12):819-24.
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    ABSTRACT: Hybrid solar cells, based on organic and inorganic semiconductors, are a promising way to enhance the efficiency of solar cells because they make better use of the solar spectrum and are straightforward to fabricate. We report on a new hybrid solar cell comprised of hydrogenated amorphous silicon (a-Si:H), [6,6]-phenyl-C71-butyric acid methyl ester ([71]PCBM), and poly-3,4-ethylenedioxythiophene poly styrenesulfonate (PEDOT:PSS). The properties of these PEDOT:PSS/a-Si:H/[71]PCBM devices were studied as a function of the thickness of the a-Si:H layer. It was observed that the open circuit voltage and the short circuit current density of the device depended on the thickness of the a-Si:H layer. Under simulated one sun AM 1.5 global illumination (100 mW cm(-2)), a power conversion efficiency of 2.84% was achieved in a device comprised of a 274 nm-thick layer of a-Si:H; this is the best performance achieved to date for a hybrid solar cell made of amorphous Si and organic materials.
    Physical Chemistry Chemical Physics 10/2013; · 4.20 Impact Factor
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    ABSTRACT: TAZ (transcriptional coactivator with PDZ-binding motif) is a transcriptional modulator that regulates mesenchymal stem cell differentiation. It stimulates osteogenic differentiation while inhibiting adipocyte differentiation. FGFs (fibroblast growth factors) stimulate several signaling proteins to regulate their target genes, which are involved in cell proliferation, differentiation, and cell survival. Within this family, FGF2 stimulates osteoblast differentiation though a mechanism that is largely unknown. In this report, we show that TAZ mediates FGF2 signaling in osteogenesis. We observed that FGF2 increases TAZ expression by stimulating its mRNA expression. Depletion of TAZ using small hairpin RNA blocked FGF2-mediated osteogenic differentiation. FGF2 induced TAZ expression was stimulated by ERK (extracellular signal-regulated kinase) activation and the inhibition of ERK blocked TAZ expression. FGF2 increased nuclear localization of TAZ and, thus, facilitated the interaction of TAZ and Runx2, activating Runx2-mediated gene transcription. Taken together, these results suggest that TAZ is an important mediator of FGF2 signaling in osteoblast differentiation.
    Bone 10/2013; · 4.46 Impact Factor
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    ABSTRACT: Abstract is missing (Quiz).
    Acta Dermato-Venereologica 09/2013;
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    ABSTRACT: Cells resembling bone marrow mesenchymal stem cells (BM-MSCs) have been isolated from glioma specimens; however, little is known about the existence of mesenchymal stem-like cells (MSLCs) in meningioma. Here, we hypothesized that cells similar to BM-MSCs exist in meningioma specimens and sought to investigate whether these putative meningioma stroma MSLCs (MS-MSLCs) could be isolated. To this end, we cultured fresh meningioma specimens using the same protocols as used previously to isolate BM-MSC. Cultured cells were analyzed for surface markers associated with BM-MSCs by fluorescence-activated cell sorting (FACS) and candidate cells were exposed to mesenchymal differentiation conditions. Possible locations of MS-MSLCs were determined by immunohistochemical analysis of sections of meningioma specimens. Spindle-shaped and, adherent cells similar to BM-MSCs were isolated in 2 of 20 meningioma specimens. FACS analysis showed that the surface markers of MS-MSLCs were similar to those of BM-MSCs and the chosen cells demonstrated an ability to differentiate into osteogenic, adipogenic and chondrogenic cells. The tumorigenicity of MS-MSLCs was tested by injection of these cells into the brain of athymic nude mice; no tumors were subsequently discovered. Immunohistochemical analyses indicated that CD105+ cells were closely associated with endothelial cells and pericytes in meningioma specimens. Our results established for the first time that cells similar to BM-MSCs exist in meningioma specimens. These cells, termed MS-MSLCs, could be one component of the meningioma cellular microenvironment.
    International Journal of Oncology 08/2013; · 2.77 Impact Factor
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    ABSTRACT: We evaluated the effectiveness of genotype- and phenotype-directed individualization of P2Y12 inhibitors to decrease high on-treatment platelet reactivity (HOPR). Sixty-five patients undergoing percutaneous coronary intervention for non-ST elevation acute coronary syndromes were randomly assigned to genotype- or phenotype-directed treatment. All patients were screened for CYP2C19(*)2, (*)3, or (*)17 alleles by using the Verigene CLO assay (Nanosphere, Northbrook, IL, USA). The P2Y12 reaction unit (PRU) was measured using the VerifyNow P2Y12 assay (Accumetrics, San Diego, CA, USA). 21 CYP2C19 (*)2 or (*)3 carriers (65.6%) and 11 patients with HOPR (33.3%), defined as a PRU value ≥230, were given 90 mg ticagrelor twice daily; non-carriers and patients without HOPR were given 75 mg clopidogrel daily. The primary endpoint was the percentage of patients with HOPR after 30 days of treatment. PRU decreased following both genotype- and phenotype-directed therapies (242±83 vs. 109±90, p<0.001 in the genotype-directed group; 216±74 vs. 109±90, p=0.001 in the phenotype-directed group). Five subjects (16.2%) in the genotype-directed group and one (3.3%) in the phenotype-directed group had HOPR at day 30 (p=0.086). All patients with HOPR at the baseline who received ticagrelor had a PRU value of <230 after 30 days of treatment. Conversely, clopidogrel did not lower the number of patients with HOPR at the baseline. Tailored antiplatelet therapy according to point-of-care genetic and phenotypic testing may be effective in decreasing HOPR after 30 days.
    Korean Circulation Journal 08/2013; 43(8):541-9.
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    ABSTRACT: We have developed a 3.5-inch flexible display driven by solution-processed organic thin-film transistors manufactured using all-sputtered electrodes. For large area and mass production of OTFTs, low-cost and low-resistance copper electrode is adopted for S/D and Gate electrodes. There is no significant degradation after delamination of plastic substrate from the glass and bending stress.
    SID Symposium Digest of Technical Papers. 06/2013; 44(1).
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    ABSTRACT: Isolated middle cerebral artery (MCA) stenosis in young patients with no other medical condition may be a unique pathologic entity with a benign long-term course. Generally, moyamoya disease shows a progression of stenosis from internal cerebral artery (ICA) to other intracranial vessel. A 26-year-old woman was admitted for choreic movements of the right arm and leg. Brain magnetic resonance imaging showed no stroke. Conventional angiography revealed 48% stenosis of the left M1 without ICA stenosis. Single photon emission computed tomography revealed perfusion asymmetry after acetazolamide injection, suggesting decreased uptake in the left basal ganglia and the cerebral cortex. Her hemichorea was mildly decreased with risperidone. One year later, follow-up angiography showed complete occlusion of the left M1 with neovascularization suggestive of moyamoya disease. The patient underwent bypass surgery and her hemichorea disappeared. This may be an atypical presentation of moyamoya disease. The bypass surgery was an effective measure for restoring the vascular insufficiency and, resultantly, controlling her hemichorea.
    Journal of movement disorders. 05/2013; 6(1):13-6.
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    ABSTRACT: Tantalum-oxide-based bi-layered resistance-change memories (RRAMs) have recently improved greatly with regard to their memory performances. The formation and rupture of conductive filaments is generally known to be the mechanism that underlies resistive switching. The nature of the filament has been studied intensively and several phenomenological models have consistently predicted the resistance-change behavior. However, a physics-based model that describes a complete bi-layered RRAM structure has not yet been demonstrated. Here, a complete electro-thermal resistive switching model based on the finite element method is proposed. The migration of oxygen vacancies is simulated by the local temperature and electric field derived from carrier continuity and heat equations fully coupled in a 3-D geometry, which considers a complete bi-layered structure that includes the top and bottom electrodes. The proposed model accurately accounts for the set/reset characteristics, which provides an in-depth understanding of the nature of resistive switching.
    Scientific Reports 04/2013; 3:1680. · 5.08 Impact Factor
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    ABSTRACT: Early detection of renal cell carcinoma using serum/plasma biomarkers remains challenging. To validate clinical performance of potential candidate markers for kidney tumors, three-marker assay composed of nicotinamide N-methyltransferase (NNMT), L-plastin (LCP1), and nonmetastatic cells 1 protein (NM23A) was evaluated. Patients with kidney cancer and control group were included in the clinical evaluation. Participants were divided into cohorts representing the training group of control group including healthy and benign tumors (n = 102) and patients with kidney cancer (n = 87) that were used to identify criteria for scoring. Then, we developed a three-marker assay that was validated with a cohort of test group samples (n = 100). A scoring method based on the cut-point of each of the three markers was used to evaluate the diagnostic performance of the marker combination. Plasma levels of NNMT, LCP1, and NM23A were highly elevated in patients with kidney cancer (P < 0.0001). In 289 blind sample tests with control subjects (n = 175) and patients with kidney cancer (n = 114), the diagnostic accuracy of NNMT alone and the three-marker assay was 0.913 and 0.932, respectively. When 90% specificity was defined, the sensitivity of NNMT and the three-marker assay was 71.9% and 95.7%, respectively. The predictive value of the three-marker assay was 87.2% (+PPV) and 97% (-PPV). The composite assay with NNMT, LCP1, and NM23A was a promising novel serum marker assay for the early detection of malignant kidney tumors covering subtypes of RCC with high diagnostic characteristics. Impact: NNMT/LCP1/NM23A triple markers could be a helpful screening assay to detect early RCC. Cancer Epidemiol Biomarkers Prev; 22(3); 390-8. ©2013 AACR.
    Cancer Epidemiology Biomarkers & Prevention 03/2013; 22(3):390-8. · 4.56 Impact Factor
  • Movement Disorders 02/2013; · 5.63 Impact Factor
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    ABSTRACT: The nature of threshold switching (TS) in AsTeGeSiN-based selector devices is comprehensively investigated. The scaling of the AC response is limited up to 5 ns due to a finite intrinsic delay time. An analytical model allows the accurate prediction of the TS nature, which can be merged to a numerical circuit simulation for providing essential guideline of the required selectivity performance.
    VLSI Technology (VLSIT), 2013 Symposium on; 01/2013
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    ABSTRACT: A rapid and sensitive chemiluminescence (CL) system coupled with a microfluidic chip has been presented to determine vitamin B12 (VB12) based on the reaction of luminol and silver nitrate (AgNO(3)) in the presence of gold nanoparticles (AuNPs). A microfluidic chip was fabricated by a soft-lithographic procedure using polydimethyl siloxane (PDMS) having four inlets and one outlet with a 200 μm wide, 250 μm deep, and 100 mm long microchannel. Ag(+) was used as a chemiluminogenic oxidant in this CL reaction which oxidized luminol to produce strong CL signal in the presence of AuNPs. Luminol reacted with AgNO(3) under the catalysis of AuNPs to produce luminol radicals which reacted with dissolved oxygen and emitted CL light. The proposed CL system was applied to determine the amount of VB12 in VB12 tablets and multivitamin. Under the optimum conditions, the CL intensity of the system was increased with the concentration of VB12 in the range of 0.25-100 ng mL(-1) with the correlation coefficient of 0.9982. The limit of detection was found to be 0.04 ng mL(-1) with the relative standard deviation of 1.56 % for five replicate determinations of 25 ng mL(-1) of VB12. The CL reaction mechanism was demonstrated by UV-visible spectra and CL emission spectra.
    Biomedical Microdevices 10/2012; · 2.72 Impact Factor
  • Biomedical Microdevices 09/2012; · 2.72 Impact Factor
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    ABSTRACT: We present the enhancement of luminescence of europium complex, Eu(3+)-ciprofloxacin (CIP), in the presence of silver nanoparticles (Ag NPs) for the CIP determination. The increment of the luminescence intensity of the Eu(3+)-CIP complex with Ag NPs was obtained due to the transfer of resonance energy to the fluorophores through the interaction of the excited-state fluorophores and surface plasmon electron in the metal nano surface. The luminescence intensity of Eu3+ was enhanced by complexation with CIP at 614 nm after excitation at 373 nm corresponding to the 5D0-7F2 transitions of Eu3+ ion. Based on the above phenomenon, a sensitive and rapid spectrofluorimetric method has been developed for the CIP determination. Linearity of the calibration curve was obtained in the range of 2.0 x 10(-10)-1.0 x 10(-8) g mL(-1) with correlation coefficient of 0.9992. The limit of detection of CIP was found to be 1.9 x 10(-11) g mL(-1) with the relative standard deviation (RSD) of 1.19% for 5 replicate measurements of 5.0 x 10(-7) g mL(-1) of CIP. The present method has been successfully applied for CIP determination in pharmaceutical and biological samples.
    Journal of Nanoscience and Nanotechnology 07/2012; 12(7):6125-30. · 1.34 Impact Factor

Publication Stats

1k Citations
218.11 Total Impact Points

Institutions

  • 2013
    • Korea University
      • Department of Life Sciences
      Sŏul, Seoul, South Korea
    • Samsung Advanced Institute of Technology
      Usan-ri, Gyeonggi Province, South Korea
    • Korea Institute of Energy Research
      • KIER-UNIST Advanced Center for Energy
      Sŏul, Seoul, South Korea
  • 2012–2013
    • Yonsei University Hospital
      • • Department of Internal Medicine
      • • Surgery
      Sŏul, Seoul, South Korea
  • 2010–2012
    • Kyungpook National University
      • • Department of Chemistry
      • • School of Dentistry
      • • Department of Oral Pathology
      Daikyū, Daegu, South Korea
  • 2006–2012
    • Seoul National University
      • • Inter-University Semiconductor Research Center
      • • Department of Materials Science and Engineering
      Sŏul, Seoul, South Korea
  • 2011
    • Kyungpook National University Hospital
      • Department of Ophthalmology
      Sŏul, Seoul, South Korea
  • 2007–2011
    • Yonsei University
      • • Department of Electrical and Electronic Engineering
      • • Department of Chemical and Biomolecular Engineering
      • • Department of Mechanical Engineering
      Seoul, Seoul, South Korea
    • Hongik University
      Sŏul, Seoul, South Korea
  • 2009–2010
    • Ulsan University Hospital
      Urusan, Ulsan, South Korea
    • Korea Railroad Research Institute
      Sŏul, Seoul, South Korea
  • 2007–2008
    • University of Seoul
      Sŏul, Seoul, South Korea
  • 2002
    • Dankook University
      Eidō, North Chungcheong, South Korea