Seung Hee Lee

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

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Publications (373)711.26 Total impact

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    ABSTRACT: Polyaniline (PAni)-coated reduced multiwall carbon nanotubes (PRMWNTs) and carbon black (CB)-filled high-density polyethylene (HDPE) composites (PRMWNTs/CB/HDPE) were prepared through a melt mixing method. Oxidized MWNTs (OMWNTs) were prepared by treating pristine multiwall carbon nanotubes (MWNTs) with an acid mixture (HNO3:H2SO4), and PAni-coated OMWNTs (POMWNTs) were synthesized via in-situ polymerization of aniline monomer in the presence of OMWNTs. POMWNTs were further reduced using hydrazine monohydrate to obtain the PRMWNTs. Fourier transform infrared (FT-IR) spectra and thermogravimetric analysis (TGA) confirmed the formation of PRMWNTs. PRMWNTs showed significantly improved thermal stability and electrical conductivity comparing to POMWNTs. The positive temperature coefficient (PTC) behavior of PRMWNTs/CB/HDPE composites revealed enhanced PTC intensity and electrical conductivity at room temperature compared to POMWNTs/CB/HDPE composites. The PRMWNTs-10/CB/HDPE composite showed high peak resistivity (301.99 MΩ-cm) and low room temperature resistivity compared to the POMWNTs/CB/HDPE composite, and thus showed the highest PTC intensity value of 6.693 as well as very excellent cyclic stability.
    Full-text · Article · Apr 2016 · Polymer Testing
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    ABSTRACT: A highly efficient circularly-polarized-light detector with excellent wavelength selectivity is demonstrated with an elegant and simple microelectronics-compatible way. The circularly-polarized-light detector based on a proper combination of the geometry-controlled TiO2-SnO2 hetero-chiral thin film as an effective chiroptical filter and the Si active layer shows excellent chiroptical response with external quantum efficiency as high as 30% and high helicity selectivity of ~15.8% in an intended wavelength range. Furthermore, we demonstrated the ability of manipulating both bandwidth and responsivity of the detector simultaneously in whole visible wavelength range by a precise control over the geometry and materials constituting hetero-chiral thin film. The high efficiency, wavelength selectivity and compatibility with conventional microelectronics processes enabled by the proposed device can result in remarkable developments in highly integrated photonic platforms utilizing chiroptical responses.
    Full-text · Article · Jan 2016 · Scientific Reports
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    ABSTRACT: Surface anchoring strength of the alignment layer on liquid crystal (LC) determines electro-optic characteristics in the LC devices. This paper investigates how azimuthal and polar anchoring strength affects the electro-optic performance of a fringe-field switching (FFS) mode associated with electrode structure, cell gap and dielectric anisotropy of the LC by numerical simulation. Our important findings in the FFS mode are that both azimuthal and polar anchoring energy can considerably affect the operating voltage and also maximum transmittance when using a LC with positive dielectric anisotropy; however, when using a LC with negative dielectric anisotropy only azimuthal anchoring energy affects electro-optic characteristics. The study proposes an optimal design of an alignment layer for maximizing transmittance in the FFS mode.
    No preview · Article · Nov 2015 · Journal of Physics D Applied Physics
  • Kyung Yeon Kim · Seung Hee Lee · Jeong Hye Kim · Pok Ja Oh
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    ABSTRACT: Purpose: The purpose of this study was to examine the mediation of psychological distress in the relationship between disturbance in ADL from chemotherapy induced peripheral neuropathy and quality of life in order to provide a basis for planning nursing interventions to improve the quality of life in cancer patients. Methods: A purposive sample of 130 patients treated with chemotherapy were recruited in the cross-sectional survey design. Data were collected using self-report questionnaires. The instruments were the Chemotherapy Induced Peripheral Neuropathy Assessment Tool (CIPNAT), Hospital Anxiety Depression Scale (HADS), and Functional Assessment of Cancer Therapy-General (FACT-G). Results: The mean score for disturbance in ADL from chemotherapy induced peripheral neuropathy was 3.30. Overall quality of life was 2.48. The mean score was 1.04 for psychological distress. The prevalence was 35.4% for anxiety and 47.7% for depression. There were significant correlations among the three variables, disturbance in ADL from chemotherapy induced peripheral neuropathy, psychosocial distress, and quality of life. Psychosocial distress had a complete mediating effect (β=-.74, p<.001) in the relationship between disturbance in ADL from chemotherapy induced peripheral neuropathy and quality of life (Sobel test: Z=-6.11, p<.001). Conclusion: Based on the findings of this study, nursing intervention programs focusing on disturbance of ADL management, and decrease of psychological distress are highly recommended to improve quality of life in cancer patients.
    No preview · Article · Nov 2015 · Journal of Korean Academy of Nursing
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    ABSTRACT: In general, surface anchoring energy is one of the most important parameters that strongly affect electrooptical performance, especially the optical response time of liquid crystal (LC) displays. In this paper, we proposed a photoalignment method for strong surface anchoring energy by applying double ultraviolet (UV) exposure with a separated bandwidth to a photosensitive polyimide layer with embedded reactive mesogens (RMs) that can increase the anchoring energy during polymerization. We first polymerized the embedded RM molecules using long wavelength UV rays (over 340 nm), and then achieved the ordered photosensitive alignment layer using short UV rays (between 254 and 340 nm). We compared the measured surface anchoring energy and the optical response time by the proposed method with the conventional UV exposure using the in-plane switching LC mode for verification. As a result, we confirmed that the anchoring energy increased two times and the optical response time improved by 22% compared with the conventional pure UV exposure method.
    No preview · Article · Nov 2015 · IEEE Transactions on Electron Devices
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    Hyunah Kwon · Seung Hee Lee · Jong Kyu Kim
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    ABSTRACT: Three-dimensional (3D) nanostructured thin films have attracted great attention due to their novel physical, optical, and chemical properties, providing tremendous possibilities for future multifunctional systems and for exploring new physical phenomena. Among various techniques to fabricate 3D nanostructures, oblique angle deposition (OAD) is a very promising method for producing arrays of a variety of 3D nanostructures with excellent controllability, reproducibility, low cost, and compatibility with modern micro-electronic processes. This article presents a comprehensive overview of the principle of OAD, and unique structural and optical properties of OAD-fabricated thin films including excellent crystallinity, accurate tunability of refractive indices, and strong light scattering effect which can be utilized to remarkably enhance performances of various systems such as antireflection coatings, optical filters, photoelectrodes for solar-energy-harvesting cells, and sensing layers for various sensors.
    Preview · Article · Sep 2015 · Nanoscale Research Letters
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    Seung Hee Lee · Hyunsoo Lee
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    ABSTRACT: The physical environment, servicescape, could serve as a differentiator in intended market segment positioning. It needs to define for facility managers their market positioning, segmentation, and target market by creating a servicescape that will meet the target customer's needs, wants and expectations. The purpose of this study is to segment users by employing a cluster analysis based on benefit sought and to suggest a strategy for designing servicescape in hotel facilities adopting Bitner's (1992) conceptual framework. This research conducted a questionnaire survey to identify the benefit sought by various market segments, and to investigate demand on servicescape in hotel facilities. Based on the results of the survey, servicescacpe design for the segment groups was developed. The customized design of the servicescape by benefit segmentation, proposed that this research could support particular positioning and segmentation strategies and enhance ultimate marketing objectives. By application of the proposed strategy, various hotel facilities can be developed for target consumers.
    Preview · Article · Sep 2015 · Journal of Asian Architecture and Building Engineering
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    ABSTRACT: Anisotropically structured upconversion nanocrystals capable of exhibiting bright upconversion emission properties are a promising new class of high performance optical materials. In this study, we investigate a facile synthetic method for the new nanoplate structure of YF3:Yb3+/Er3+ with enhanced luminescence intensity. The shape of YF3:Yb3+/Er3+ nanocrystals can be controlled by changing the synthesis conditions of the NaOH concentration, reaction time, and surfactant. The concentration of NaOH determines the final structure of YF3:Yb3+/Er3+. By increasing the NaOH concentration from 0.25 mmol to 2.5 mmol, YF3:Yb3+/Er3+ nanoplates transform into NaYF4:Yb3+/Er3+ nanoparticles; in the absence of NaOH, the nanoplate structure of YF3:Yb3+/Er3+ changes to particles. The YF3:Yb3+/Er3+ nanoplates show luminescence efficiency much greater than that of the spherical YF3:Yb3+/Er3+ nanocrystals. This journal is
    No preview · Article · Sep 2015 · Journal of Materials Chemistry C
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    ABSTRACT: Multiwalled carbon nanotubes (MWCNTs) exhibited distinct electrical stretching behavior in nematic liquid crystals (NLC) depending on nanotube surface state. We found that two different samples prepared by chemical functionalization (f-CNT) and physical grinding (g-CNT) revealed distinct field dependence from each other. The threshold stretching field was lower in the f-CNT aggregates than in g-CNT aggregates. This was attributed to polar functionality induced weakened van der Waals interaction in f-CNTs, which was confirmed in infrared (IR) and Raman spectroscopy. Dynamic reorientation of f-CNTs was observed under polarized optical microscopy where f-CNTs were found to follow orientation of NLC director. Uniformly aligned f-CNTs also exhibited selective light absorption in sufficiently long transient field off-state which could find potential applications in memory and modulator devices as well as the versatile functional composites.
    No preview · Article · Sep 2015
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    Namhee Kim · Seung Hee Lee · Jongyoun Yi · Chulhun L Chang
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    ABSTRACT: Peptide nucleic acid (PNA) probes are artificial DNA analogues with a hydrophobic nature that can penetrate the mycobacterial cell wall. We evaluated a FISH method for simultaneous detection and identification of Mycobacterium tuberculosis (MTB) and non-tuberculous mycobacteria (NTM) in clinical respiratory specimens using differentially labeled PNA probes. PNA probes targeting the mycobacterial 16S ribosomal RNA were synthesized. The cross-reactivity of MTB- and NTM-specific probes was examined with reference strains and 10 other frequently isolated bacterial species. A total of 140 sputum specimens were analyzed, comprising 100 MTB-positive specimens, 21 NTM-positive specimens, and 19 MTB/NTM-negative specimens; all of them were previously confirmed by PCR and culture. The PNA FISH test results were graded by using the United States Centers for Disease Control and Prevention-recommended scale and compared with the results from the fluorochrome acid-fast bacterial stain. The MTB- and NTM-specific PNA probes showed no cross-reactivity with other tested bacterial species. The test results demonstrated 82.9% agreement with the culture results with diagnostic sensitivity of 80.2% and diagnostic specificity of 100.0% (kappa=0.52, 95% confidence interval: 0.370-0.676). Dual-color PNA FISH showed high specificity for detecting and identifying mycobacteria in clinical specimens. However, because of its relatively low sensitivity, this method could be more applicable to culture confirmation. In application to direct specimens, the possibility of false-negative results needs to be considered.
    Preview · Article · Sep 2015 · Annals of Laboratory Medicine
  • Seung Hee Lee · Jong Won Park · Koo Young Yoon

    No preview · Article · Aug 2015
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    ABSTRACT: High quality flower-like NiCo2O4 has been fabricated on three-dimensional (3D) graphene foam (GF) and used as an electrode for supercapacitors. The 3D GFs are prepared through chemical vapor deposition (CVD) followed by the electro-deposition of flower-like NiCo2O4. The NiCo2O4/3D GF nanohybrids are characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy analysis. The lack of defects in the 3D GF ensures the formation high quality graphene sheets by CVD method. The supercapacitor performances of the electrode materials are evaluated through cyclic voltammetry, charge-discharge analysis and electrochemical impedance spectroscopy. A maximum specific capacitance of 1402 F g−1 is achieved at a current density of 1 A g−1. The NiCo2O4/3D GF nanohybrid-based supercapacitors exhibit long-cycle stability with a 76.6% retention in specific capacitance after 5000 cycles at a current density of 5 A g−1. The high electrochemical performance is attributed to the synergistic effects of the high electrical conductivity and large surface area of 3D GF along with the catalytic activity of the flower-like NiCo2O4.
    Full-text · Article · Aug 2015 · Carbon
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    ABSTRACT: Electrically tunable focusing microlens arrays based on polarization independent optical phase of nano liquid crystal droplets dispersed in polymer matrix are demonstrated. Such an optical medium is optically isotropic which is so-called an optically isotropic liquid crystals (OILC). We not only discuss the optical theory of OILC, but also demonstrate polarization independent optical phase modulation based on the OILC. The experimental results and analytical discussion show that the optical phase of OILC microlens arrays results from mainly orientational birefringence which is much larger than the electric-field-induced birefringence (or Kerr effect). The response time of OILC microlens arrays is fast~5.3ms and the tunable focal length ranges from 3.4 mm to 3.8 mm. The potential applications are light field imaging systems, 3D integrating imaging systems and devices for augment reality.
    Full-text · Article · Jun 2015 · Optics Express
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    ABSTRACT: A simple single-step method to fabricate spatially graded TiO<sub>2</sub>-SiO<sub>2</sub> Bragg stack with rainbow colored photonic band gap is presented. The gradation in thickness of the Bragg stack was accomplished with a modified glancing angle deposition (GLAD) technique with dynamic shadow enabled by a block attached to one edge of the rotating substrate. A linear gradation in thickness over a distance of about 17 mm resulted in a brilliant colorful rainbow pattern. Interestingly, the photonic band gap position can be changed across the whole visible wavelength range by linearly translating the graded Bragg stack over a large area substrate. The spatially graded Bragg stack may find potential applications in the tunable optical devices, such as optical filters, reflection gratings, and lasers.
    No preview · Article · Jun 2015 · Optics Express
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    ABSTRACT: Uniformly oriented macroscopic monodomain of cholesteric blue phase liquid crystal has been realised by the influence of surface anchoring. Orientation of the lattice planes in surface-treated (ST) and non-surface-treated (NST) cell were analysed and compared by Kossel diagram technique. NST cell has revealed the green and blue domains corresponding to reflection from oriented (110) and (112) planes of the body-centred cubic lattice. However, in the ST cell only the lattice plane (110) oriented uniformly and tailored the macroscopic monodomain. Electric field driven reorientation of the (110) lattice plane was noticed in NST cell whereas for ST cell such reorientation was absent. Two distinct electric field-induced capacitive responses have been observed in the two different cells. In NST cell anomalous electrostriction was observed, whereas for ST cell normal electrostriction was observed. Interestingly, the capacitance has decreased with an increasing electric field for anomalous electrostriction in NST cell, whereas for normal electrostriction in ST cell it was increased with increasing the field. Such a capacitive change behaviour is explained by dielectric anisotropic change followed by the electric field induced elongation and contraction of the cubic unit cell along and perpendicular to the electric field.
    No preview · Article · Jun 2015 · Liquid Crystals
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    ABSTRACT: We investigated how the electro-optic characteristics of the fringe-field switching (FFS) liquid crystal (LC) mode are affected by elastic constants of LCs. Unlike conventional liquid crystal (LC) devices, in which mainly the dielectric torque determines reorientation of LC, the field-induced LC reorientation in the fringe-field switching (FFS) mode is controlled first by dielectric torque and then by pure elastic torque between LCs so that the transmittance oscillates along the electrode positions. We find that elastic constants of the LC play an important role on the field-induced dynamics of the LC molecules such that the higher the splay constant is, the higher the light efficiency becomes, which is a unique characteristic of the FFS mode. The results present an important design of physical properties of LC to enhance better transmittance in the FFS mode.
    No preview · Article · Jun 2015 · Liquid Crystals
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    ABSTRACT: A reduced graphene oxide (RGO)-NiFe2O4 nanocomposite was synthesized by a simple one step hydrothermal approach and its application in the electrocatalytic oxidation of hydrazine was demonstrated. The as-synthesized nanocomposite was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, UV-visible spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Thermogravimetric analysis, Field emission-scanning electron microscopy (FE-SEM), and Transmission electron microscopy (TEM). The FE-SEM and TEM image analyses revealed that the NiFe2O4 nanoparticles were uniformly distributed on the RGO sheets with a diameter and length of ∼10 and ∼100 nm, respectively. The XPS analysis confirmed the ionic states of Ni and Fe to be Ni3+ and Ni2+, and Fe2+ and Fe3+, respectively. Further, the electrochemical activity of the RGO-NiFe2O4 nanocomposite was investigated by studying the oxidation of hydrazine. The RGO-NiFe2O4 modified glassy carbon electrode (GCE) showed an outstanding electrocatalytic activity towards the oxidation of hydrazine as compared to the NiFe2O4 and RGO modified electrodes. The enhanced electrocatalytic activity is due to the synergistic effect between RGO and NiFe2O4. Using amperometry, the lowest detection limit of 200 nM was achieved with the RGO-NiFe2O4 modified GCE. Therefore, the RGO-NiFe2O4 modified GCE can be used for the electrochemical oxidation of hydrazine.
    Full-text · Article · Jun 2015 · Composites Part B Engineering
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    ABSTRACT: We report the H2 and LPG gas sensing behavior of RGO/SnO2 QDs synthesized by surfactant assisted hydrothermal method. The RGO/SnO2 QDs based sensor shows high response ~89.3% to H2 and ~92.4% to LPG for 500 ppm test gas concentration at operating temperatures 200 °C and 250 °C, respectively. Further, the RGO/SnO2 QDs based sensor shows good selectivity to H2 and LPG in the presence of other interfering gases such as ammonia, chloroform, toluene, benzene, acetone, n-butylacetate, acetic acid and formic acid. We observed that the gas response to H2 is 29.8 times higher than that of acetic acid whereas gas response to LPG is 17.8 times higher than that of formic acid. The long-term analyses have also been performed to demonstrate the reproducible nature of RGO/SnO2 QDs based sensor over passing time which shows excellent reproducibility.
    Full-text · Article · Jun 2015 · Nanoscale
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    ABSTRACT: The fringe-field switching (FFS) mode that uses liquid crystals (LC) with negative dielectric anisotropy is used in high resolution FFS-LCD owing to its higher transmittance over positive LC. In this paper, the FFS mode with electrode width 1 µm and distances between the electrodes 1.5 µm is proposed. In such an electrode structure, operating voltage (Vop) decreases with decreasing cell gap to 2 µm so that a proper Vop, high LC's light efficiency of 90%, and a fast response time less than 10 ms, can be achieved, which maximizes electro-optic performance of the FFS mode. In addition, the color temperature of a white state becomes higher in the fine patterned FFS cell.
    No preview · Article · Jun 2015
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    ABSTRACT: Defects in graphene governs electrical and optical properties. Although grain boundaries in graphene inevitably formed during large area synthesis process, which act as scattering centers for charge carriers to degrade mobility, have been studied extensively, point defects have been rarely investigated mainly due to the absence of facile observation tools. Here, we report polarized optical microscopy to observe defect distributions in monolayer graphene. This was realized by aligning liquid crystal s (LC) on graphene where the defect population was modulated by irradiating ultraviolet (UV) light directly on graphene surface under moisture condition. Aromatic rings in LC molecules are oriented with hexagonal rings in graphene to have preferred orientation, providing a way to identify relative orientations of graphene domains and point defects. Our studies show that point defects generated by prolonged UV irradiation time give rise to irregular LC alignment with disclination lines on the graphene surface and a large-size LC domain associated with graphene single domain eventually disappeared. This indicates that defects associated with oxygen-containing functional groups cause to reduce the strong stacking interaction between graphene and LC molecules.
    No preview · Article · Jun 2015 · Optics Express

Publication Stats

3k Citations
711.26 Total Impact Points

Institutions

  • 2002-2016
    • Chonbuk National University
      • • Department of Polymer Nano Science & Technology
      • • Division of Advanced Materials Engineering
      Tsiuentcheou, Jeollabuk-do, South Korea
  • 2014-2015
    • Pohang University of Science and Technology
      • Department of Materials Science and Engineering
      Geijitsu, Gyeongsangbuk-do, South Korea
    • Yale University
      New Haven, Connecticut, United States
    • Kyungpook National University Hospital
      Sŏul, Seoul, South Korea
    • Kangbuk Samsung Hospital
      Sŏul, Seoul, South Korea
  • 2001-2015
    • Yonsei University
      Sŏul, Seoul, South Korea
  • 1989-2015
    • Jeonju National University of Education
      Tsiuentcheou, Jeollabuk-do, South Korea
  • 2013-2014
    • Pusan National University
      • Department of Laboratory Medicine
      Busan, Busan, South Korea
    • University of Ulsan
      • Department of Nursing
      Ulsan, Ulsan, South Korea
    • University of Akron
      • College of Polymer Science and Polymer Engineering
      Akron, Ohio, United States
    • Southern Illinois University Carbondale
      Illinois, United States
    • Catholic University of Korea
      Sŏul, Seoul, South Korea
  • 2006-2013
    • Sungkyunkwan University
      • • Institute of Basic Science
      • • Department of Physics
      Sŏul, Seoul, South Korea
  • 2005-2013
    • Gwangju Institute of Science and Technology
      • Department of Life Sciences
      Gwangju, Gwangju, South Korea
    • Seoul National University Hospital
      • Department of Thoracic and Cardiovascular Surgery
      Sŏul, Seoul, South Korea
  • 2003-2012
    • Hongik University
      • Department of Chemical Engineering
      Sŏul, Seoul, South Korea
    • Inje University
      Kŭmhae, Gyeongsangnam-do, South Korea
  • 2011
    • Ewha Womans University
      Sŏul, Seoul, South Korea
  • 2009-2011
    • Catholic University of Daegu
      • Department of Ophthalmology
      Kayō, Gyeongsangbuk-do, South Korea
  • 2008-2011
    • University of Texas at Austin
      • School of Nursing
      Austin, Texas, United States
    • Korea Photonics Technology Institute
      Sŏul, Seoul, South Korea
    • Inha University Hospital
      Sinhyeon, Gyeongsangnam-do, South Korea
  • 2005-2011
    • Seoul National University
      • • College of Veterinary Medicine
      • • Department of Agricultural Biotechnology
      Sŏul, Seoul, South Korea
  • 2010
    • Catholic Sangji College
      Antō, North Gyeongsang, South Korea
  • 2005-2009
    • Inha University
      • College of Medicine
      Chemulpo, Incheon, South Korea
  • 2007
    • National Institutes of Health
      Maryland, United States
  • 2004
    • CHA University
      • College of Medicine
      Sŏul, Seoul, South Korea
  • 2000-2001
    • Hong-ik university
      United States
    • Asan Medical Center
      Sŏul, Seoul, South Korea
  • 1998
    • Samsung Advanced Institute of Technology
      Usan-ri, Gyeonggi Province, South Korea
  • 1996
    • Kent State University
      • Liquid Crystal Institute
      Kent, OH, United States