Jae Won Yang

CHA University, Seoul, Seoul, South Korea

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Publications (34)105.4 Total impact

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    ABSTRACT: The polymer-supported transfer of chemical vapor deposition (CVD)-grown graphene provides large-area and high-quality graphene on a target substrate; however, the polymer and organic solvent residues left by the transfer process hinder the application of CVD-grown graphene in electronic and photonic devices. Here, we describe an inverse transfer method (ITM) that permits the simultaneous transfer and doping of graphene without generating undesirable residues by using polymers with different functional groups. Unlike conventional wet transfer methods, the polymer supporting layer used in the ITM serves as a graphene doping layer placed at the interface between the graphene and the substrate. Polymers bearing functional groups can induce n-doping or p-doping into the graphene depending on the electron donating or withdrawing characteristics of functional groups. Theoretical models of dipole layer-induced graphene doping offered insights into the experimentally measured change in the work function and the Dirac point of the graphene. Finally, the electrical properties of pentacene field effect transistors prepared using graphene electrodes could be enhanced by employing the ITM to introduce a polymer layer that tuned the work function of graphene. The versatility of polymer functional groups suggests that the method developed here will provide valuable routes to the development of applications of CVD-grown graphene in organic electronic devices.
    ACS Nano 07/2014; · 12.03 Impact Factor
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    ABSTRACT: Oxalate nephropathy is commonly caused by ethylene glycol, vitamin C, and foods like star fruit that contain a lot of oxalate. Peanuts also have high oxalate contents. However, case reports of peanut-induced oxalate nephropathy are not common. Here, we describe a case of peanut-induced acute oxalate nephropathy with acute kidney injury and intend to demonstrate the conditions under which peanut-induced oxalate nephropathy is likely to occur.
    Kidney Research and Clinical Practice. 06/2014;
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    ABSTRACT: Aims: Urinary cystatin C has been suggested as a useful biomarker for diagnosis of acute kidney injury (AKI). Multiple myeloma is often complicated by AKI. Therefore, we investigated whether the urinary cystatin C was available for diagnosis of AKI in multiple myeloma. Materials and methods: This study included 39 patients with monoclonal gammopathy of undetermined significance (MGUS) or multiple myeloma. We reviewed the medical records retrospectively and investigated whether urinary γ-globulin and myeloma progression had effects on urinary cystatin C excretion. Results: Spearman's correlation analysis showed that serum β2-microglobulin and serum cystatin C had a significant positive correlation with the urinary cystatin C excretion (r = 0.513, p = 0.001, r = 0.659, p < 0.001) and FEcystatinC (r = 0.585, p = 0.002, r = 0.711, p < 0.001). The GFRcr also had a significant negative correlation with the urinary cystatin C excretion (r = -0.582, p < 0.001) and FEcystatinC (r = -0.474, p = 0.002). In addition, the urinary γ-globulin had a significant positive correlation with the urinary cystatin C excretion (r = 0.678, p < 0.001) and FEcystatinC (r = 0.731, p < 0.001). Urinary γ-globulin was the most significant factor to influence urinary cystatin C excretion in multiple regression test. Conclusion: These results indicate that urinary γ-globulin and myeloma progression can increase the fractional and total excretion of urinary cystatin C. Therefore, it is believed that the urinary cystatin C can be affected by urinary γ-globulin and myeloma progression in the diagnosis of AKI in multiple myeloma. In addition, urinary γ-globulin is believed to be the most significant factor to influence on urinary cystatin C.
    Clinical nephrology 05/2014; 81(5):345-349. · 1.29 Impact Factor
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    ABSTRACT: Purpose: Estimation of body fluid volume in hyponatremia is useful for diagnosis and therapeutic decision-making. Physical examination has been generally used to estimate body fluid volume, but it depends on the physician's abilities. Bioimpedance spectroscopy has been suggested to be a reliable method for the estimation of body fluid volume. Therefore, this study investigated whether bioimpedance spectroscopy could replace physical examination in hyponatremia. Materials and Methods: The study included 30 patients with hyponatremia. At the time of the initial visit, body fluid volume was estimated simultaneously by both physical examination and bioimpedance spectroscopy. Estimation of body fluid status by clinical diagnosis was performed as well, which determined body fluid status corresponds with the most likely cause of hyponatremia (clinical body fluid estimation). Results: The results of body fluid volume estimated by physical examination, bioimpedance spectroscopy, and clinical body fluid estimation showed that 9, 10, and 9 patients, respectively, were hypervolemic; 13, 15 and 16 patients, respectively, were euvolemic; and 8, 5, and 5 patients, respectively, were hypovolemic. Cohen's kappa analysis showed a significant agreement between physical examination and bioimpedance spectroscopy (kappa coefficient, 0.632, p<0.001). In addition, bioimpedance spectroscopy showed a higher level of agreement with clinical body fluid estimation than physical examination (kappa coefficient, 0.602 vs. 0.524). Conclusion: This study suggests that bioimpedance spectroscopy could replace physical examination for estimating body fluid status in hyponatremia. In addition, bioimpedance spectroscopy might correspond better with clinical diagnosis than physical examination in the estimation of body fluid status in hyponatremia.
    Yonsei medical journal 03/2014; 55(2):482-6. · 0.77 Impact Factor
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    ABSTRACT: Epitaxial semiconductor/graphene double heterostructures are fabricated by vapor-phase van der Waals epitaxy of InAs on both sides of suspended graphene, as reported on page 6847. K. S. Kim, Y. J. Hong and co-workers demonstrate that the weak van der Waals attraction facilitates a preferential growth direction of InAs exclusively along the As-polar direction, which results in a polarity inversion of the double heterostructures. The first-principles and density functional calculations clarify why and how the conductive graphene layer yields the polarity inversion for sp(3) /sp(2) /sp(3) -type double heterostructures.
    Advanced Materials 12/2013; 25(47):6914. · 14.83 Impact Factor
  • Psychiatry research. 11/2013;
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    ABSTRACT: Background: Autism spectrum disorder (ASD) is a neurobiological disorder characterized by distinctive impairments in cognitive function, language, and behavior. Linkage and population studies suggest a genetic association between solute carrier family 6 member 4 (SLC6A4) variants and ASD. Method: Logistic regression was used to identify associations between single-nucleotide polymorphisms (SNPs) and ASD with 3 alternative models (additive, dominant, and recessive). Linear regression analysis was performed to determine the influence of SNPs on Childhood Autism Rating Scale (CARS) scores as a quantitative phenotype. Results: In the present study, we examined the associations of SNPs in the SLC6A4 gene and the fibrinogen alpha chain (FGA) gene. Logistic regression analysis showed a significant association between the risk of ASD and rs2070025 and rs2070011 in the FGA gene. The gene-gene interaction between SLC6A4 and FGA was not significantly associated with ASD susceptibility. However, polymorphisms in both SLC6A4 and the FGA gene significantly affected the symptoms of ASD. Conclusion: Our findings indicate that FGA and SLC6A4 gene interactions may contribute to the phenotypes of ASD rather than the incidence of ASD. © 2013 S. Karger AG, Basel.
    Neuropsychobiology 11/2013; 68(4):212-220. · 2.37 Impact Factor
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    ABSTRACT: Autism spectrum disorder (ASD) is a neurodevelopmental syndrome associated with impairments of reciprocal communication and cognitive function. Associations between single-nucleotide polymorphisms (SNPs) and ASD were analysed by logistic regression. Polymorphisms in FNDC3A exhibited significant associations in genotype and diplotype analyses. We conclude that FNDC3A influences the prevalence of ASD.
    Psychiatry research. 04/2013;
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    ABSTRACT: Background: The cyclosporin A (CsA) nephrotoxicity limits its usefulness as an immunosuppression. We studied the administration of both nitroprusside and phosphodiesterase-5 inhibitor (udenafil) in order to determine whether these agents could ameliorate the renal injury in CsA nephrotoxicity. Methods: 30 8-week-old SD rats were divided into 5 groups: the control (1), SQ with 15 mg/kg CsA (Group 2), CsA along with 5 mg/kg IP nitroprusside (Group 3), CsA with 10 mg/kg PO udenafil (Group 4), and CsA with udenafil and nitroprusside (Group 5). Results: Group showed an increase in creatinine compared o the control group. Group 5 showed a decrease in creatinine compared to Group 2. In TUNEL, Group 2 increased apoptosis in proximal tubules compared to control. Group 5 showed a decrease in apoptosis compared to Groups 2, 3, and 4. In IHC, the eNOS in Group 2 was stronger than in the controls. Groups 3, 4, and 5 showed decreased staining intensity compared to Group 2. In IHC, the VEGF in Groups 2, 3, and 4 increased compared to the controls. The eNOS protein expression was increased in both Groups 3 and 5 compared to the controls. The VEGF protein expression was increased in Groups 3 and 5 compared to Group 2. The eNOS mRNA was decreased in Group 2 compared to the control group and tended to increase in Groups 3, 4, and 5 compared to Group 2. The VEGF mRNA was increased in Group 2 and tended to increase more in Groups 3 and 5. Conclusion: The udenafil and nitroprusside ameliorated renal injury in rat model of CsA nephrotoxicity. The mechanism appears to be associated with decreasing tubular apoptosis by decreasing eNOS and increasing VEGF.
    Clinical nephrology 02/2013; · 1.29 Impact Factor
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    ABSTRACT: BACKGROUND:: Genetic variations in interleukin 28B (IL28B) have been strongly associated with a sustained virological response (SVR) in European and African-American patients. Genetic variation of IL28B was investigated in healthy controls and chronic hepatitis C (CHC) patients, and the treatment response in the CHC patients was analyzed according to IL28B polymorphism in the Korean population. METHODS:: IL28B polymorphisms (rs12979860 and rs8099917) were studied in 200 healthy controls and in 167 CHC patients who were treated with peginterferon-α and ribavirin. RESULTS:: The prevalence of rs12979860 in healthy controls is as follows: the CC-genotype was 88.5%, the CT-genotype was 11.5%, and the TT-genotype was not found. The prevalence of rs8099917 in healthy controls is as follows: the TT-genotype was 89.5%, the TG-genotype was 10.5%, and the GG-genotype was not found. The CC-genotype of rs12979860 and the TT-genotype of rs8099917 were found to be closely related (linkage disequilibrium; D'=1.0, χ=0.9082). In 106 CHC patients treated with peginterferon and ribavirin, the SVR was 67.2% (n=58) for 1b, 91.6% (n=47) for 2a. In hepatitis C virus (HCV) genotype 1b with respect to rs12979860, the SVR in CC-genotype was 72.9% and that in CT-genotype was 40.0%. On investigating predictive factors for SVR, pretreatment low-HCV RNA levels, HCV genotype non-1, early virological response, and also the IL28B CC-genotype for rs12979860 were good indicators of an SVR. CONCLUSIONS:: In Korea, genetic variation of IL28B is different from that in western countries in view of high prevalence of rs12979860 CC-genotype. It seems likely that a high SVR in Korean patients with genotype 1 CHC patients is due to the genetic polymorphism in IL28B.
    Journal of clinical gastroenterology 02/2013; · 2.21 Impact Factor
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    ABSTRACT: Despite intense studies of carbon nanotubes for decades, the separation of semiconducting and metallic single-walled carbon nanotubes (SWNTs) remains to be one of the most important tasks to be resolved. Here we demonstrate that a K atom binds the semiconducting SWNTs more strongly than the metallic SWNTs, while this binding strength hierarchy is reversed for a K+ ion, consistent with experimental reports. This was shown by first-principles calculations, which properly describe the van der Waals interactions, and the origin of such results is explained. These results could be exploited as useful guidance toward separating semiconducting and metallic SWNTs via noncovalent functionalization.
    The Journal of Physical Chemistry C. 02/2013; 117(8):4309–4313.
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    ABSTRACT: Here, we report a substrate-induced intercalation phenomenon of an organic solvent at the interface between monolayer graphene and a target substrate. A simple dipping of the transferred chemical vapor deposition (CVD)-grown graphene on the SiO(2) substrate into chloroform (CHCl(3), CF), a common organic solvent, induces a spontaneous formation of CF clusters beneath the basal plane of the graphene as well as inside the wrinkles. The microscopic and spectroscopic observations showed the doping behavior of monolayer graphene, which indicates the adsorption of CF to monolayer graphene. Interestingly, the intercalated organic solvent showed remarkable stability for over 40 days under ambient conditions. To reveal the underlying mechanism of the stable solvent intercalation, desorption energy of CF molecules at the graphene/substrate interface was measured using Arrhenius plots of the conductance change upon time and temperature. Two stages of solvent intercalations with high desorption energies (70 and 370 meV) were observed along with the consecutive shrinkage of the solvent clusters at the basal plane and the wrinkles, respectively. Moreover, the theoretical calculation based on density functional theory (DFT) also shows the strong intercalation energy of CF between monolayer graphene and the SiO(2) substrate, which results from the stabilization of the graphene-SiO(2) interactions. Furthermore, the thermal response of the conductance could be utilized to maintain a certain degree of p-doping of monolayer graphene, which provides the facile, sustainable, and controllable large-area doping method of graphene for future generation of printed flexible electronics.
    ACS Nano 01/2013; · 12.03 Impact Factor
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    ABSTRACT: Diastolic dysfunction occurs frequently in patients with chronic kidney disease (CKD) and is associated with heart failure (HF) or mortality. We investigated whether the ratio of early diastolic mitral inflow velocity to early diastolic mitral annulus velocity (E/e' ratio), estimated using tissue Doppler imaging, has prognostic value for cardiovascular morbidity and all-cause mortality in patients with CKD. For 186 patients with CKD of stages III to V, we obtained echocardiograms with tissue Doppler imaging. A 5-year follow-up of 136 patients was performed based on hospital records and telephone interviews. The enrolled patients (79 males and 57 females) were categorized into the following CKD subgroups: stage III (n = 25); stage IV (n = 22); and stage V (n = 89). The average follow-up period was 30.45 months and the mean age of the patients was 61.13 years. The mortality rate after 5 years was 60.0%. The causes of death were: sepsis, 21.9%; HF, 16.2%; and sudden death, 15.2%. Age (p = 0.000), increased C-reactive protein level (p = 0.018), and increased E/e' ratio (p = 0.048) were found to correlate with mortality. Age (p = 0.000), decreased ejection fraction (p = 0.003), and increased E/e' ratio (p = 0.045) correlated with cardiovascular event. The E/e' ratio can predict mortality and cardiovascular events in patients with CKD who have diastolic dysfunction.
    The Korean Journal of Internal Medicine 01/2013; 28(1):35-44.
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    ABSTRACT: Nurr1 is an orphan nuclear receptor best known for its essential role in the development and maintenance of midbrain dopaminergic (DA) neurons. During DA neurogenesis, Nurr1 directly targets human tyrosine hydroxylase (hTH). Here we investigated this targeting to identify the molecular mechanisms by which Nurr1 regulates DA neurogenesis. We previously cloned the hTH promoter and found three consensus elements for Nurr1 binding: NBRE-A, -B, and -C. In the present study, gel retardation and luciferase assays using hTH constructs showed that Nurr1 preferentially bound to NBRE-A, through which it mediated transcriptional activity. Furthermore, Nurr1 displayed dual-function transcriptional activities depending on the cell type. In DA-like SH-SY5Y cells, Nurr1 dose-dependently stimulated hTH-3174 promoter activity by 7- to 11-fold. However, in the human neural stem cell (hNSC) line HB1.F3, Nurr1 strongly repressed transcription from the same promoter. This repression was relieved by mutation of only the NBRE-A element and by nicotinamide [an inhibitor of class III histone deacetylases (HDACs), such as SIRT1], but not by trichostatin A (an inhibitor of class I and II HDACs). SIRT1 was strongly expressed in the nucleus of HB1.F3 cells, while it was localized in the cytoplasm in SH-SY5Y cells. ChIP assays of HB1.F3 cells showed that Nurr1 overexpression significantly increased the SIRT1 occupancy of the NBRE-A hTH promoter region, while low SIRT1 levels were observed in control cells. In contrast, no significant SIRT1 recruitment was observed in SH-SY5Y cells. These results indicate that differential SIRT1 localization may be involved in hTH gene regulation. Overall, our findings suggest that Nurr1 exists in dual transcriptional complexes, including co-repressor complexes that can be remodeled to become co-activators and can fine-tune hTH gene transcription during human DA neurogenesis.
    PLoS ONE 01/2013; 8(8):e71469. · 3.53 Impact Factor
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    ABSTRACT: Hepatitis C virus (HCV) infection is a major cause of liver disease, including cirrhosis and hepatocellular carcinoma. Due to significant adverse effects and emergence of resistant strains of currently developed anti-HCV agents, plant extracts have been considered to be potential sources of new bioactive compounds against HCV. The aim of this study was to evaluate the functional effects of triterpenoid saponins contained in the root extract of Platycodon grandiflorum (PG) on viral enzyme activities and replication in both HCV replicon cells and cell culture grown HCV- (HCVcc-) infected cells. Inhibitory activities of triterpenoid saponins from PG were verified by NS5B RNA-dependent RNA polymerase assay and were further confirmed in the context of HCV replication. Six triterpenoid saponins (platycodin D, platycodin D2, platycodin D3, deapioplatycodin D, deapioplatycodin D2, and platyconic acid A), PG saponin mixture (PGSM), were identified as active components exerting anti-HCV activity. Importantly, PGSM exerted synergistic anti-HCV activity in combination with either interferon- α or NS5A inhibitors. We demonstrated that combinatorial treatment of PGSM and IFN- α efficiently suppressed colony formation with significant reduction in drug resistant variant of HCV. These data suggest that triterpenoid saponin may represent a novel anti-HCV therapeutic agent.
    Evidence-based Complementary and Alternative Medicine 01/2013; 2013:560417. · 1.72 Impact Factor
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    ABSTRACT: Sustained virologic response (SVR) for the treatment of chronic hepatitis C (CHC) may differ with ethnicity due to differences in genetic traits. This study evaluated the efficacy of peginterferon and ribavirin, and the association between IL28B genotypes and the treatment efficacy in Korean CHC patients. This was a retrospective cohort study using data from medical records. Eighty-five CHC patients were eligible for assessment of the efficacy of antiviral therapy, and 47 patients were available for an IL28B genetic study, which was performed using the Multiplex tetra-primer PCR method for rs12979860. Overall, the early virologic response rate was 87.1%: 84.9% in HCV genotype 1 and 90.6% in genotype 2. The overall end-of-treatment virologic response rate was 81.2%: 75.5% in genotype 1 and 90.6% in genotype 2. The overall SVR rate was 81.2%: 75.5% in genotype 1 and 90.6% in genotype 2. For rs12979860, the frequencies of polymorphisms were 89% for the CC type, 11% for the CT type, and 0% for the TT type. Their overall SVR rate was 87% (39/47): 90.5% (38/42) for the CC type and 20% (1/5) for the CT type. For genotype 1, SVR rates were 88% (21/24) for the CC type and 0% (0/4) for the CT type. Multivariate analysis revealed that the IL28B-CC type was a good predictor for SVR. The SVR of the combination therapy in Koreans was higher than that observed in Western countries. This finding might be attributable to the high prevalence of IL28B-CC type among Koreans, which may be a good predictor of SVR.
    Clinical and molecular hepatology. 12/2012; 18(4):360-7.
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    ABSTRACT: Arsenic is a terribly poisonous material. There have been many reports of arsine poisoning in workers, and a few have discussed acute kidney injury by arsine. But literatures which investigated the pathologic findings are uncommon, and especially, the ones describing ultrastructural findings are rare. Here, we report an incident of acute arsine poisoning complicated by acute kidney injury and suggest the characteristics of the renal pathology in arsine-induced renal injury, especially the ultrastructural findings.
    Renal Failure 11/2012; · 0.94 Impact Factor
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    ABSTRACT: Pathogenesis of Parkinson's disease and related catecholaminergic neurological disorders is closely associated with changes in the levels of tyrosine hydroxylase (TH). Therefore, investigation of the regulation of the TH gene system should assist in understanding the pathomechanisms involved in these neurological disorders. To identify regulatory domains that direct human TH expression in the central nervous system (CNS), we generated two transgenic mouse lines in which enhanced yellow fluorescent protein (EYFP) is expressed under the control of either 3.2-kb (hTHP-EYFP construct) human TH promoter or 3.2-kb promoter with 2-kb 3'-flanking regions (hTHP-ex3-EYFP construct) of the TH gene. In the adult transgenic mouse brain, the hTHP-EYFP construct directs neuron-specific EYFP expression in various CNS areas, such as olfactory bulb, striatum, interpeduncular nucleus, cerebral cortex, hippocampus, and particularly dentate gyrus. Although these EYFP-positive cells were identified as mature neurons, few EYFP-positive cells were TH-positive neurons. On the other hand, we could detect the EYFP mRNA expression in a subset of neurons in the olfactory bulb, midbrain, and cerebellum, in which expression of endogenous TH is enriched, with hTHP-ex3-EYFP transgenic mice. These results indicate that the 3.2-kb sequence upstream of the TH gene is not sufficient for proper expression and that the 2-kb sequence from the translation start site to exon 3 is necessary for expression of EYFP in a subset of catecholaminergic neurons.
    Journal of Neuroscience Research 06/2012; 90(10):1949-59. · 2.97 Impact Factor
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    ABSTRACT: The measurement of glomerular filtration rate (GFR) applying serum creatinine (Cr) does not reflect the GFR of patients accurately, and thus recently, studies on the measurement of GFR applying serum cystatin-C (Cys-C) have been conducted. We investigated the relationship between Cys-C and proteinuria in patients with chronic kidney disease. We compared the biochemical test, including serum Cys-C, the amount of proteinuria and the concentration of Cys-C measured by the 24-h urine test, and the difference of GFR on 105 patients who visited our hospital in 6 months (January to June 2007). Among 105 patients, 58 patients were males, and the mean age was 56.74 ± 16.31 years. With regard to underlying diseases, the group with diabetes had 76 patients and the group showing nephrotic proteinuria [nephrotic syndrome (NS)] had 29 patients. The GFR-Cys-C in the NS group (44.17 ± 26.32 mL/min) was higher than in the non-NS group (33.68 ± 14.29 mL/min; p = 0.041). The fractional excretion (FE) of Cys-C increased according to FE of albumin ( p = 0.000) and GFR-modification of diet in renal disease (MDRD) equation (p = 0.000). Serum Cys-C increased according to corrected urine Cys-C (p = 0.010). The GFR calculated by serum Cys-C decreased according to FE of albumin (p = 0.003). The degree of difference between GFR-Cys-C and GFR-MDRD was negatively correlated according to the FE of albumin (p = 0.001). We confirmed that urinary excretion of Cys-C could be altered by previously known mechanisms such as proteinuria. Difference between GFR-Cys-C and GFR-MDRD was negatively correlated according to FE of albumin.
    Renal Failure 05/2012; 34(6):676-84. · 0.94 Impact Factor

Publication Stats

93 Citations
105.40 Total Impact Points

Institutions

  • 2013
    • CHA University
      • Department of Biomedical Science
      Seoul, Seoul, South Korea
  • 2006–2013
    • Ajou University
      • • Brain Disease Research Center
      • • Institute for Medical Sciences
      Sŏul, Seoul, South Korea
  • 2002–2013
    • Yonsei University Hospital
      • Department of Internal Medicine
      Seoul, Seoul, South Korea
  • 2012
    • Yonsei University
      Sŏul, Seoul, South Korea
  • 2011–2012
    • Pohang University of Science and Technology
      • Department of Chemistry
      Andong, North Gyeongsang, South Korea