SunWon Kim

Al2O3 nanotubes and nanorods fabricated by coating and filling of carbon nanotubes with atomic-layer deposition

Aluminum oxide (Al2O3) nanotubes and nanorods were fabricated by coating and filling of multiwalled carbon nanotubes (MWNTs) with atomic-layer deposition (ALD). Al2O3 material was deposited on the MWNTs at a substrate temperature of 300°C using trimethylaluminum and distilled water. Transmission electron microscopy, high resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, and selected area electron diffraction of the deposited MWNTs revealed that amorphous Al2O3 material coats the MWNTs conformally and that this material fills the inside of the MWNTs. These illustrate that ALD has an excellent capability to coat and fill any three-dimensional shapes of MWNTs conformally without producing any crystallites.

Magnetostriction of melt-spun Dy-Fe-B alloys

The magnetostriction of melt‐spun ribbons of Dyx(Fe1−yBy)1−x (x=0.2, 0.25, 0.3; 0≤y≤0.2) alloys is systematically investigated as a function of the wheel speed during melt quenching. As the wheel speed increases from 10 to 50 m/s, the magnetic softness improves with the wheel speed rather continuously for the alloys with the Dy content x=0.2 and 0.25 but it exhibits a maximum at the wheel speed of 30 or 40 m/s for the alloys with the highest B content (x=0.3). The softness also improves with the B content for a fixed wheel speed. Homogeneous and ultrafine grain structure is observed for the first time even in the as‐spun state when the ribbons of the alloy Dy0.3(Fe0.8B0.2)0.7 are fabricated at the wheel speed of 30 m/s. The ribbon having the ultrafine grain structure exhibits good magnetic softness together with a high strain.

Trends in the incidence rate of device-associated infections in intensive care units after the establishment of the Korean Nosocomial Infections Surveillance System

BACKGROUND The effectiveness of continuous nationwide surveillance on healthcare-associated infections should be investigated in each country. AIM To assess the rate of device-associated infections (DAIs) in intensive care units (ICUs) since the establishment of the Korean Nosocomial Infections Surveillance System (KONIS). METHODS Nationwide data were obtained on the incidence rate of DAI in ICUs reported to KONIS by all participating hospitals. The three major DAIs were studied: ventilator-associated pneumonia (VAP), central line-associated bloodstream infection (CABSI), and catheter-associated urinary tract infection (CAUTI). The pooled and year-wise incidence rates (cases per 1000 device-days) of these DAIs were determined for the period 2006 and 2012. In addition, data from institutions that had participated in KONIS for at least three consecutive years were analysed separately. FINDINGS The number of ICUs participating in KONIS gradually increased from 76 in 2006 to 162 in 2012. Between 2006 and 2012, the incidence rate per 1000 device-days for VAP decreased significantly from 3.48 to 1.64 (F = 11, P < 0.01), for CAUTI the rate decreased non-significantly from 1.85 to 1.26 (F = 2.02, P = 0.07), and for CABSI the rate also decreased non-significantly from 3.4 to 2.57 (F = 1.73, P = 0.12). In the 132 ICUs that had participated in KONIS for at least three consecutive years, the VAP rate significantly decreased from the first year to third year (F = 20.57, P < 0.01), but the rates of CAUTI (F = 1.06, P = 0.35) and CABSI (F = 1.39, P = 0.25) did not change significantly. CONCLUSION The decreased incidence rate of VAP in ICUs in Korea might be associated with the continuous prospective surveillance provided by KONIS.

Coronary Stent Fracture Complicated Multiple Aneurysms Confirmed by 3-Dimensional Reconstruction of Intravascular-Optical Coherence Tomography in a Patient Treated With Open-Cell Designed Drug-Eluting Stent

A 55-year-old man with a previous history of cerebral infarct and hypertension presented to our cardiovascular center complaining of angina in November 2011. Chronic total occlusion in the proximal left anterior descending artery was identified by coronary angiography (Figure 1A). The patient subsequently underwent percutaneous coronary intervention. Wiring was done successfully with a tapered stiff wire (Conquest Pro 20; ASAHI INTECC). After multiple predilation, a single drug-eluting stent (3.0 × 18 mm) of an open-cell design and bioabsorbable polymer (Nobori; Terumo, Tokyo, Japan) was implanted using a 3.5-mm noncompliant balloon (inflation pressure, 24 atmospheric pressure; Quantum Maverick Balloon; Boston Scientific/Scimed, Maple Grove, MN) for application of final high-pressure postdilation (Figure 1B). The patient has been asymptomatic since percutaneous coronary intervention and on dual antiplatelet therapy. A 6-month scheduled angiographic follow-up demonstrated a structural misalignment at the stent implantation site with a change in focal aneurysm (Figure 1C). Digital subtraction imaging by StentBoost (Subtract; Philips Healthcare, Best, The Netherlands) was done under the suspicion of stent distortion, but the imaging was unclear to clarify the diagnosis (Figure 1D). To determine the precise configuration of the stent, we performed intravascular optical coherence tomography (OCT). Conventional 2-dimensional (2-D) OCT revealed a focal thrombus and 2 additional aneurysms …

Trends in the distribution and antimicrobial susceptibility of causative pathogens of device-associated infection in Korean intensive care units from 2006 to 2013: results from the Korean Nosocomial Infections Surveillance System (KONIS).

BACKGROUND For all countries, information on pathogens causing healthcare-associated infections is important in order to develop proper strategies for preventing and treating nosocomial infections. AIM To assess the change in frequencies and antimicrobial resistance of pathogens causing device-associated infections (DAIs) in intensive care units (ICUs) in South Korea between July 2006 and June 2014. METHODS Data from the Korean Nosocomial Infections Surveillance System (KONIS) were analysed, including three major DAI types in ICUs. FINDINGS The frequency of Gram-negative bacteria gradually increased for central line-associated bloodstream infection (CLABSI) and ventilator-associated pneumonia (VAP) (from 24.6% to 32.6% and from 52.8% to 73.5%, respectively). By contrast, the frequency of Gram-positive bacteria decreased from 58.6% to 49.2% for CLABSI, and from 44.3% to 23.8% for VAP (P < 0.001). Staphylococcus aureus was the most frequent causative pathogen in CLABSI throughout the surveillance period, but for VAP was replaced as the most frequent pathogen by Acinetobacter baumannii as of 2010. Candida albicans was the most frequent pathogen for catheter-associated urinary tract infection. The meticillin resistance rate in S. aureus decreased from 95% to 90.2% (P < 0.001); amikacin resistance in Klebsiella pneumoniae and Escherichia coli decreased from 43.8% to 14.7% and from 15.0% to 1.8%, respectively (P < 0.001); imipenem resistance in A. baumannii increased from 52.9% to 89.8% (P < 0.001). CONCLUSION The proportion of Gram-negative bacteria as nosocomial pathogens for CLABSI and VAP has increased. The prevalence of A. baumannii causing DAIs in Korean ICUs has increased rapidly, as has the rate of carbapenem resistance in these bacteria.

Generation of functionally mature dendritic cells from elutriated monocytes using polyinosinic : polycytidylic acid and soluble CD40 ligand for clinical application

Despite the increasing use of dendritic cell (DC) vaccination in clinical trials, optimal conditions for the generation of functionally mature DCs remain to be established. The current standard DC maturation protocol for clinical trials has been used as an inflammatory cytokine cocktail [tumour necrosis factor (TNF)‐α, interleukin (IL)‐1β, IL‐6 and prostaglandin E2], but this cocktail induced insufficient maturation of DCs derived from elutriated monocytes when cultured in X‐VIVO 15. The aim of this study was to define effective combinations of stimulators for generating functionally mature DCs from elutriated monocytes under current good manufacturing practice conditions. We compared the functional capacity of DCs in response to all possible pairwise combinations of four different classes of stimuli: TNF‐α, peptidoglycan, polyinosinic : polycytidylic acid [poly(I:C)] and soluble CD40 ligand (CD40L). Maturation status of DCs stimulated with combination of four stimuli was similar to that of the cytokine cocktail as assessed by the cell surface phenotype. However, only the combination of poly(I:C) + CD40L induced complete functional activation of the whole DC population, assessing IL‐12p70 production, allostimulatory activity, migratory response to CCL19 and T helper 1‐polarizing capacity. Thus, the protocol based on the combination of poly(I:C) and CD40L is more effective for the induction of clinical‐grade DCs from elutriated monocytes than the standard cytokine cocktail.

The characteristics of metallophthalocyanine mono-, multilayer and application to the gas sensor for NO2

Abstract The preparation of Langmuir-Blodgett(LB) films of metallophthalocyanines(MPcs) with symmetric octa(2-ethylhexyloxy) side chain and their possible use in gas sensing device were examined. Complexed central metal ion, which include copper, lead, platinum, cobalt and dihydrogen was varied and 2-ethylhexyl chains were substituted at both 2- and 3-position of each bingo ring in the phthalocyanine compound. Mono- and multilayer LB films were transferred to a 6 MHz quartz crystal microbalance(QCM) by vertical dipping method. The interaction or responses of film coated QCM to NO 2 have been tested, and after the heat treatment, the good recovery efficiencies were achieved for repeated use.

Magnetic properties and reliabilities of FeXN (X=Ti,Al,Hf,CoHf,CrHf) nanocrystalline thin film head materials

A series of FeN and FeXN (X=Ti,Al,Hf,CoHf,CrHf) films were prepared by reactive RF magnetron sputtering. These FeXN films exhibit good soft magnetic properties with low coercivity (<2 Oe) and high moment (15-20 kG). To investigate the reliability of these films, we performed the thermal stability and electrochemical corrosion test for pure Fe, Permalloy, FeN and FeXN films. The results show that the direction of the magnetic anisotropy of FeTiN, FeCoHfN and FeCrHfN is not nearly changed by the DC magnetic field of 100 Oe perpendicular to the easy axis at 150/spl deg/C, for up to 3 hrs. The electrochemical corrosion tests were performed in 0.5 M NaCl electrolyte. Permalloy shows the best corrosion resistance in the films but the addition of Cr to FeHfN films significantly improves the corrosion resistance, to be nearly as good as Permalloy. This improvement results from the formation of a negative oxide layer.

Five-year decreased incidence of surgical site infections following gastrectomy and prosthetic joint replacement surgery through active surveillance by the Korean Nosocomial Infection Surveillance System

BACKGROUND Surveillance of healthcare-associated infection has been associated with a reduction in surgical site infection (SSI). AIM To evaluate the Korean Nosocomial Infection Surveillance System (KONIS) in order to assess its effects on SSI since it was introduced. METHODS SSI data after gastrectomy, total hip arthroplasty (THA), and total knee arthroplasty (TKA) between 2008 and 2012 were analysed. The pooled incidence of SSI was calculated for each year; the same analyses were also conducted from hospitals that had participated in KONIS for at least three consecutive years. Standardized SSI rates for each year were calculated by adjusting for SSI risk factors. SSI trends were analysed using the Cochran-Armitage test. FINDINGS The SSI rate following gastrectomy was 3.12% (522/16,918). There was a significant trend of decreased crude SSI rates over five years. This trend was also evident in analysis of hospitals that had participated for more than three years. The SSI rate for THA was 2.05% (157/7656), which decreased significantly from 2008 to 2012. The risk factors for SSI after THA included the National Nosocomial Infections Surveillance risk index, trauma, reoperation, and age (60-69 years). The SSI rate for TKA was 1.90% (152/7648), which also decreased significantly during a period of five years. However, the risk-adjusted analysis of SSI did not show a significant decrease for all surgical procedures. CONCLUSION The SSI incidence of gastrectomy and prosthetic joint replacement declined over five years as a result of active surveillance by KONIS.

Analysis of Machining Stability for a Parallel Machine Tool

Abstract Machine tool chatter is a self-excited vibration generated by chip thickness variation. It severely degrades the quality of the machined surface. The incidence of chatter is greatly affected by the dynamic characteristics of machine tool structure. This article extends chatter stability analysis to a machine tool equipped with a parallel mechanism. The vibration model of a parallel machine tool is derived, in which the legs of the parallel mechanism are considered as spring-damper systems. Then, the regenerative cutting dynamics is combined with the vibration model and stability analysis is performed. The chatter stability charts for various machining parameters are examined, with the example of the cubic parallel mechanism that is specially designed for machine tool use.