Hye Sung Kim

Seoul National University, Sŏul, Seoul, South Korea

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Publications (58)143.67 Total impact

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    ABSTRACT: Indium tin oxide (ITO) films with various thicknesses from 104 nm to 513 nm were prepared onto polyethylene terephthalate (PET) substrates by using r.f. magnetron sputtering without intentionally heating the substrates. The structural, optical, and electrical properties of ITO films were investigated as a function of film thickness. It was found that the amorphous nature of the ITO film was dominant below the thickness of about 200 nm but the degree of the crystallinity increased with an increasing thickness above the thickness of about 250 nm, resulting in the increase of carrier concentration and therefore reducing the electrical resistivity from 5.1×10−3 to 9.4 × 10−4 Ω ·cm. The average transmittance (400–800 nm) of the ITO deposited PET substrates decreased as the film thickness was increasing and was above 80% for the thickness below 315 nm. The results show that the improvement of the film crystallinity with the film thickness contributes to the increase of the carrier concentration and the enhancement of the electrical conductivity.
    No preview · Article · Feb 2016 · Journal of Nanoscience and Nanotechnology
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    ABSTRACT: AlN/Cu composite powders with a core-shell structure were synthesized by a new technique using electroless plating of Cu on AlN particles and consolidated by spark plasma sintering (SPS). Dependence of the thermal conductivity and coefficient of thermal expansion (CTE) of the AlN/Cu composites on the particle size of AlN were studied. The thermal conductivity and coefficient of thermal expansion were significantly dependent on the existence of both boundary pores surrounding the Cu-coated AlN particles and the internal pores of the AlN particles. In order to eliminate the pores, the temperature and pressure of SPS were increased and the lIN particles were heat-treated at high temperature. Adoption of the core-shell AlN/Cu composite powders facilitated the fabrication of AlN/Cu composites with low porosity and uniform distribution in the AlN in Cu matrix.
    No preview · Article · Dec 2015 · Taehan-Kŭmsok-Hakhoe-chi = Journal of the Korean Institute of Metals and Materials
  • Young Ju Son · Hye Sung Kim · Dong Hoon Choi · Hyuk Sang Yoo
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    ABSTRACT: Nanofiber is a flexible and highly porous mesh that is advantageous for coating bare metal stent and local drug delivery. Herein, we developed drug-eluting stent coated with PCL/PU blending coaxial nanofiber for controlling drug release manner and suppressing in-stent restenosis, which is a representative side effect of stenting surgery. The shell of coaxial electrospun nanofibrous are composed of poly (ε-caprolactone) (PCL) and polyurethane (PU) for biodegradability and elasticity to the polymeric coating of stent. Paclitaxel (PTX) is loaded into both the core and shell through electrospinning using coaxial nozzle with different weight ratio. The morphology of nanofiber-coated stent, expansion state, and core/shell structure of nanofiber were visualized by scanning electron microscope and transmission electron microscope. As more amount of PCL/PU was infused from the outer nozzle, PTX release speed from the nanofiber was increased. And PTX suppressed L6 cell proliferation in vitro expecting potential possibility of PTX-loaded coaxial nanofiber as a drug-eluting stent coating material. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2015.
    No preview · Article · Dec 2015 · Journal of Biomedical Materials Research Part B Applied Biomaterials
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    ABSTRACT: A CaO-SiO2 layer was deposited on a pure magnesium substrate that had been prepared by using the spark plasma sintering of atomized powders via a sol-gel process. Various concentrations of tetraethyl orthosilicate (TEOS) were added during the synthesis of the CaO-SiO2 nanocomposites on the pure magnesium substrate; the effects of the TEOS concentration on the corrosion protection and the adhesive properties of the material were investigated. The total thickness of the coating layer ranged from approximately 6 to 10 μm and was affected by the TEOS concentration. Despite the slight surface cracking that occurred on the coating as a result of the strain induced by the annealing process during the deep coating procedure, excellent corrosion and adhesive properties were observed when the TEOS concentration was higher than 15 vol%. When the TEOS concentration was increased to 15 vol%, the corrosion resistance was enhanced, but the adhesive strength was unaffected. Therefore, to produce a CaO-SiO2 coating on pure magnesium for bio-applications, we consider the optimal TEOS concentration to be higher than 15%.
    No preview · Article · Dec 2015 · Journal- Korean Physical Society
  • Seoung Mo Koo · G.-H. Kim · Dae Youn Hwang · Hye Sung Kim
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    ABSTRACT: The microstructural evolution and mechanical properties during mechanical milling of pure magnesium powders were investigated as a function of the milling time and processing control agent. Commercially pure magnesium powders were mechanically milled in a SPEX 8000 shaker Mixer/Mill in an inert atmosphere. From the TEM observations and the analysis of the X-ray diffraction patterns, the steady state grain size was approximately 75 nm regardless of the addition of a processing control agent, while the milling time to reach steady state was shorter when a processing control agent (lwt% stearic acid) was added to the pure magnesium. It is noteworthy that the steady state hardness of the pure magnesium with the processing control agent was hardly different from that of the pure magnesium milled without PCA. Hence, we conclude that the oxides present in the magnesium surface function the same as that of the PCA, and their effectiveness is dependent on the characteristics of the magnesium surface oxides broken by mechanical milling.
    No preview · Article · Oct 2015 · Taehan-Kŭmsok-Hakhoe-chi = Journal of the Korean Institute of Metals and Materials
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    ABSTRACT: During the first trimester of pregnancy, thyroid-stimulating hormone (TSH) >2.5 mIU/L has been suggested as the universal criterion for subclinical hypothyroidism. However, TSH levels change continuously during pregnancy, even in the first trimester. Therefore the use of a fixed cut-off value for TSH may result in a different diagnosis rate of subclinical hypothyroidism according to gestational age. The objective of this study was to obtain the normal reference range of TSH during the first trimester in Korean gravida and to determine the diagnosis rate of subclinical hypothyroidism using the fixed cut-off value (TSH >2.5 mIU/L). The study population consisted of pregnant women who were measured for TSH during the first trimester of pregnancy (n=492) and nonpregnant women (n=984). Median concentration of TSH in pregnant women was lower than in non-pregnant women. There was a continuous decrease of median TSH concentration during the first trimester of pregnancy (median TSH concentration: 1.82 mIU/L for 3+0 to 6+6 weeks; 1.53 mIU/L for 7+0 to 7+6 weeks; and 1.05 mIU/L for 8+0 to 13+6 weeks). Using the fixed cut-off value of TSH >2.5 mIU/L, the diagnosis rate of subclinical hypothyroidism decreased significantly according to the gestational age (GA) at TSH (25% in 3+0 to 6+6 weeks, 13% in 7+0 to 7+6 weeks, and 9% for 8+0 to 13+6 weeks, P<0.001), whereas the diagnosis rate was 5% in all GA with the use of a GA-specific cut-off value (P=0.995). Therefore, GA-specific criteria might be more appropriate for the diagnosis of subclinical hypothyroidism.
    Preview · Article · Sep 2015 · Journal of Korean medical science
  • Seong Mo Koo · H.-G. Jeong · T.-S. Kim · Hye Sung Kim
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    ABSTRACT: Optimum heat treatment conditions to improve the hardness and corrosion resistance of ternary Mg-Ca-Zn alloys have been studied, based on the theoretical models and DSC (Differential scanning calorimetry) experimental data. Two-step heating process at 420 °C and 480 °C has been applied and we have found that the low melting point phase, Ca2Mg6Zn3 can effectively be dissolved into a-Mg matrix without premature melting. Due to preceding treatment at lower temperature followed by the second stage solid solution heat treatment at 480 °C, Mg-1.4 wt%Ca-xwt%Zn alloys (x=0, 1.5 and 4.0) exhibit improved corrosion resistance than that from the single step solid solution treated alloy at 480 °C. However, aging treatment of the alloy at 200 °C has led to the homogeneous precipitation of Ca2Mg6Zn3 and Mg2Ca phases in the matrix as well as at the grain boundary. This microstructural change results in the deterioration of corrosion resistance mainly originated from galvanic corrosion between the matrix and the precipitates. The hardness of Mg-1.4%Cax%Zn alloy, on the other hand, significantly increases with Zn addition by applying two-step solid solution and aging heat treatment.
    No preview · Article · Sep 2015 · Taehan-Kŭmsok-Hakhoe-chi = Journal of the Korean Institute of Metals and Materials
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    ABSTRACT: Gold nanoparticles (AuNP) and quantum dots (Qdot) were clicked into doxorubicin nanoclusters that showed enzyme-dependent dissociation behaviors for differential cellular uptakes and imaging. The AuNP were co-functionalized with doxorubicin (DOX) and azide-terminated polymer (DOX/azide@AuNP), while an enzyme-cleavable peptide and alkyne-terminated polymer were sequentially conjugated on Qdot surface (Alkyne-MMP@Qdot). Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and fluorescence imaging detected the azide and alkyne groups on DOX/azide@AuNP and Alkyne-MMP@Qdot, respectively, and the click-reactivity was also confirmed. In the presence of the catalyst, two nanoparticles were clicked to doxorubicin nanoclusters, which increased the volume of the particles ca. 343-fold within 30min. Upon matrix metalloproteinase-2 (MMP-2) digestion, the nanoclusters were clearly dissociated into smaller particles, and the fluorescence of the quenched Qdot was also recovered, which suggests that the nanoclusters respond to MMP-2 concentrations and can thus be employed for cancer imaging. Confocal microscopy and an elemental analysis of the cancer cells revealed that the cellular uptakes of doxorubicin nanoclusters significantly increased at higher MMP-2 concentrations, and doxorubicin could also be cleaved for anti-cancer effects. In vivo and in vitro cytotoxicity assay accordingly showed that the cytotoxicity of doxorubicin nanoclusters against cancer cells increased in MMP-2-rich environments such as tumor site. Thus, these nanoclusters containing DOX/azide@AuNP and Alkyne-MMP@Qdot are expected to be multifunctional carriers for targeted anti-cancer treatments and imaging. Copyright © 2015. Published by Elsevier B.V.
    No preview · Article · Aug 2015 · Journal of Controlled Release
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    Hye Sung Kim · Hyuk Sang Yoo
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    ABSTRACT: Focal adhesion between substrates and cells greatly controls cytoskeletal changes as well as differentiation of the cultivating cells. We here investigated focal adhesion behaviors and differentiation profiles of adipose-derived stem cells on the nano-scaled pillar arrays with diverse pillar-to-pillar distances.
    Preview · Article · Jun 2015 · RSC Advances
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    ABSTRACT: Bacteria cellulose membranes (BCM) are used for wound dressings, bone grafts, tissue engineering, artificial vessels, and dental implants because of their high tensile strength, crystallinity and water holding ability. In this study, the effects of BCM application for 15 days on healing of burn wounds were investigated based on evaluation of skin regeneration and angiogenesis in burn injury skin of Sprague-Dawley (SD) rats. BCM showed a randomly organized fibrils network, 12.13MPa tensile strength, 12.53% strain, 17.63% crystallinity, 90.2% gel fraction and 112.14g×m(2)/h highest water vapor transmission rate (WVTR) although their swelling ratio was enhanced to 350% within 24h. In SD rats with burned skin, the skin severity score was lower in the BCM treated group than the gauze (GZ) group at all time points, while the epidermis and dermis thickness and number of blood vessels was greater in the BCM treated group. Furthermore, a significant decrease in the number of infiltrated mast cells and in vascular endothelial growth factor (VEGF) and angiopoietin-1 (Ang-1) expression was observed in the BCM treated group at day 10 and 15. Moreover, a significant high level in collagen expression was observed in the BCM treated group at day 5 compared with GZ treated group, while low level was detected in the same group at day 10 and 15. However, the level of metabolic enzymes representing liver and kidney toxicity in the serum of BCM treated rats was maintained at levels consistent with GZ treated rats. Overall, BCM may accelerate the process of wound healing in burn injury skin of SD rats through regulation of angiogenesis and connective tissue formation as well as not induce any specific toxicity against the liver and kidney. Copyright © 2014 Elsevier Ltd. All rights reserved.
    No preview · Article · May 2015
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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.
    Full-text · Article · Feb 2015 · Annals of Dermatology
  • Ka Ram Kim · Hye Sung Kim · Soon Hong Kwon · D.-Y. Hwang
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    ABSTRACT: Many studies have shown that particle boundaries in spark plasma sintering (SPS) can be easily removed by using a combination of sintering temperature and pressure. We already reported that a degassing treatment prior to sintering by SPS was a critical step to remove particle-particle boundaries effectively and to obtain a magnesium alloy having high strength and high ductility. In this study, the microstructural evolution and the mechanical properties of nanocrystalline Mg-6%Al alloys were investigated to determine the effect of sintering pressure combined with an appropriate degassing treatment.
    No preview · Article · Dec 2014 · Journal- Korean Physical Society
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    ABSTRACT: The microstructure and characteristics of silicon-incorporated diamond-like carbon film, fabricated using a radio-frequency plasma-enhanced chemical vapor deposition process with hexamethyldisilane [(CH3)3Si·Si(CH3)3:HMDS] gas as a silicon source, were investigated. Diamond-like carbon films with silicon compositions from 0 to 5 atomic percent were deposited onto ultra-fine grained AZ31 magnesium alloy substrate as buffer layers or multilayers. Si doping led not only to an increase in the bonding ratio (sp3/sp2), but improvements in hardness, critical adhesion, and corrosion resistance. Out of the investigated samples, the multi-deposited silicon diamond-like carbon thin film on magnesium substrate showed the best combination of adhesive, wear resistance, and corrosion resistance properties.
    No preview · Article · Dec 2014 · Journal of Nanoscience and Nanotechnology
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    ABSTRACT: This study aimed to check the status of the contact investigation in congregate settings to eradicate tuberculosis (TB) in the Republic of Korea. The "Integrated System for Disease and Public Health Management" is used for care and follow-up for patients and contacts of TB. We downloaded data for contact investigations conducted from January to December 2013. A total of 1,200 contact investigations in congregate settings were carried out by 25 field investigators in 2013. We performed the status of contact investigation, TB, and LTBI rate by age, accept rate of LTBI treatment, and complete rate of LTBI treatment during 2013. A total of 1,547 index TB patients, 149,166 contacts, and 259 additional TB patients were found through the investigation. Kindergartens showed the highest LTBI rate, 19.8%, among educational facilities. The second highest was in elementary schools and the subtotal LTBI rate of educational facilities was 7.8%. Social welfare/correctional facilities and workplaces showed relatively high LTBI rates of 23.8% and 23.6%, respectively. By age, individuals >35 years showed the highest LTBI rate, followed by those aged 0-4 years, 30-34 years, and 5-9 years, with rates of 18.1%, 16.4%, and 15.4% respectively. When comparing the tuberculin skin test (TST) positive conversion ratio by facility, middle school and high school were relatively high compared to the others. The accept rate of LTBI treatment in the workplace was lowest at 63% and the complete rate in elementary schools was lowest at 76.5%. TB contact investigation is considered as a meaningful strategy for preventing TB outbreaks in congregate settings and decreasing the prevalence of TB in young people. Results of this study could be used to establish the LTBI management policy.
    Full-text · Article · Dec 2014
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    ABSTRACT: Microstructural changes and corrosion behavior of pure magnesium for different milling times were investigated. The samples with a finer grain size showed poor corrosion resistance because of unstable or metastable protective film formation after immersion in 0.8 wt% NaCl solution. The corrosion resistance did not improve despite the strong (0002) texture of the sample prepared by spark plasma sintering at 500 degrees C for 0.3 Ks and milling for 2 h. By studying the microstructural changes and texture development, we concluded that the deformation-dependent grain size is the dominant factor controlling the corrosion properties of mechanically milled magnesium. Increased grain boundary densities lead to an enhancement of the overall surface reactivity and, consequently, the corrosion rate.
    No preview · Article · Nov 2014 · Metals and Materials International
  • Hye Sung Kim · Hyuk Sang Yoo

    No preview · Article · Sep 2014 · Journal of Controlled Release
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    ABSTRACT: Background Idiopathic interstitial pneumonia (IIP) is characterized by chronic interstitial inflammation and fibrosis. Although mounting evidence has suggested that toll-like receptor (TLR) 2 and TLR4 are involved in the pathogenesis of non-infectious lung injury in vitro and in mouse models, their roles in human IIP remain unknown. Methods To address this issue, we investigated the expression patterns of TLR2 and TLR4 by immunohistochemistry in resected lung tissues from patients with usual interstitial pneumonia (UIP) or nonspecific interstitial pneumonia (NSIP). Results Type II pneumocytes, bronchial epithelial cells (BECs), and alveolar macrophages accounted for the majority of TLR2- and TLR4-expressing cells in both UIP and NSIP. The numbers of TLR2 and TLR4-positive respiratory epithelial (RE) cells, including type II pneumocytes and BECs, were significantly greater in UIP and NSIP than in the control. In particular, the numbers of TLR2-positive RE cells were much greater in UIP than in NSIP. The intensities of TLR2 and TLR4 expression in type II pneumocytes were also significantly stronger in UIP and NSIP than in the control. A comparison of the TLR expression patterns between the fibroblastic and fibrotic areas in UIP indicated that the numbers TLR2 and TLR4-positive RE cells were similar in fibroblastic areas, whereas the TLR2-positive RE cells outnumbered the TLR4-positive RE cells in the fibrotic areas. Conclusions This study demonstrates that RE cells over-express TLR2 and TLR4 in the lungs of IIP patients. These findings suggest that high expression of TLRs may contribute to the pathogenesis of human IIP.
    No preview · Article · May 2014 · Respiratory medicine
  • Hye Sung Kim · Hyuk Sang Yoo
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    ABSTRACT: Fabricating tissue architecture-mimicking scaffolds is one of the major challenges in the field of tissue engineering. Electrospun nanofibers have been considered as potent techniques for fabricating fibrous scaffolds biomimicking extracellular frameworks. Therapeutic agent-incorporated nanofibrous meshes have widely served as excellent substrates for adhesion, proliferation and differentiation. Many drugs, proteins and nucleic acids were incorporated into the scaffolds for regeneration of skin, musculoskeletal, neural and vascular tissue engineering in aims to control the release of the therapeutic agents. In the current article, we focus on introducing various fabrication techniques for electrospun nanofiber-based scaffolds and subsequent functionalization of nanofibers for therapeutic purposes. We also detail how the therapeutic nanofibrous meshes can be employed in the field of tissue engineering.
    No preview · Article · Apr 2014 · Nanomedicine
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    ABSTRACT: This study was carried out to investigate the residual characteristics and calculate processing factor of the environment friendly material matrine in fresh chilli pepper by drying. Spray solution of matrine was prepared by dilution of the commercial product (2% active ingredient) with water at 1 : 1000 (v/v) ratio and sprayed onto chilli pepper plants at seven day intervals. Samples were collected at 0, 1, 3, 5 and 7 days after last application and then dried using a hot air dry oven at for 36 hours until the water content was reduced to 14%. Recoveries and storage period stabilities of matrine in the samples ranged from 106.6 to 119.1% and 106.6 to 113.1%, respectively. The residual concentrations of matrine in fresh chilli pepper and dried chilli peppers treated only once were found to be from less than 0.01 to 0.11 and from 0.03 to 0.25 mg/kg, respectively. In case of plants sprayed twice with matrine, the residual concentrations ranged from 0.02 to 0.12 and from 0.04 to 0.4 mg/kg, respectively. Processing factor of matrine in the fresh chilli pepper by drying was found to be from 1.5 to 3.3, indicating that the residual concentration of matrine in dried chilli pepper increased about two or three times by drying.
    Full-text · Article · Dec 2013
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    Byung Ju Song · Ka Ram Kim · Hye Sung Kim
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    ABSTRACT: Microstructural and mechanical properties of Ni-YSZ fabricated using SPS processing have been investigated at various sintering temperatures. Our study shows samples to be applied as a SOFC anode have the proper porosity of 40% and high hardness when processed at . These results are comparable to the values obtained at higher sintering temperature reported by others. This result is important because when the fabrication processes are performed above , the mechanical property starts to decrease drastically. This is caused by the fast grain coarsening at the higher temperature, which initiates a mismatch between thermal expansion coefficients of Ni and YSZ and induces cracks as well.
    Preview · Article · Dec 2013

Publication Stats

309 Citations
143.67 Total Impact Points

Institutions

  • 2010-2015
    • Seoul National University
      • Department of Biomedical Sciences
      Sŏul, Seoul, South Korea
    • Seoul National University Hospital
      • Department of Pathology
      Sŏul, Seoul, South Korea
  • 2009-2015
    • Kangwon National University
      • • Department of Mechanical and Biomedical Engineering
      • • Department of Forest Biomaterials Engineering
      Shunsen, Gangwon-do, South Korea
  • 2007-2015
    • Catholic University of Korea
      • • Department of Dermatology
      • • Department of Internal Medicine
      • • College of Medicine
      Sŏul, Seoul, South Korea
  • 2006-2015
    • Pusan National University
      • • College of Nanoscience and Nanotechnology
      • • Department of Nanomaterials Engineering
      Tsau-liang-hai, Busan, South Korea
  • 2014
    • Korea Centers for Disease Control and Prevention
      Daiden, Daejeon, South Korea
  • 2011
    • Hongik University
      • Department of Materials Science and Engineering
      Sŏul, Seoul, South Korea