Yura Kim

Fabrication of monodisperse silica-polymer core-shell nanoparticles with excellent antimicrobial efficacy

Monodisperse nanoparticles with antimicrobial polymer shells were fabricated using a seeded copolymerization; they exhibited excellent antibacterial activities against gram-positive bacteria as well as gram-negative bacteria.

Correlation between clinical diagnosis based on RDC/TMD and MRI findings of TMJ internal derangement

This study was conducted to investigate the value of magnetic resonance imaging (MRI) in the diagnostic process based on the Research Diagnostic Criteria for Temporomandibular Disorder (RDC/TMD) by evaluating agreement between RDC/TMD and MRI diagnosis of disc displacement (DD) and correlation amongst MRI findings such as DD, joint effusion (JE), degenerative change and superior lateral pterygoid muscle (SLPM) attachment. Randomly selected MRIs of 200 joints from 100 TMD patients differentiated into RDC/TMD group II representing DD by clinical examination were reviewed retrospectively. The results show that Cohens kappa value was 0.336 showing overall disagreement between RDC/TMD group II and MRI diagnoses (P<0.001). The Cohens kappa value for group IIa, DD with reduction (DDWR), was -0.223 (P<0.01) showing disagreement, whilst the value was 0.546 for group IIb, DD without reduction (DDWOR) with limited opening, and 0.490 for group IIc, DDWOR without limited opening, showing moderate agreement (P<0.001). JE was detected with a higher probability as the state of DD advanced (P<0.001) and when degenerative joint changes were present (P<0.05). The difference of DD according to SLPM attachment was insignificant. MRI could be used when clinical examination cannot predict the true position of the disc.

Burden of disease attributable to obesity and overweight in Korea.

Objective:To estimate the burden of disease attributable to overweight and obesity using disability-adjusted life-year (DALY) in Korea.Research methods:Firstly, overweight and obesity-related diseases and their relative risk (RR) were selected by the systematic review. Secondly, population-attributable fractions (PAFs) were computed by using the formula including RR and the prevalence of exposure (Pe) of overweight and obesity. Thirdly, DALYs of overweight and obesity-related diseases in Korea were estimated. Finally, the attributable burden (AB) of diseases due to overweight and obesity was calculated as the sum of the products from multiplying DALYs of overweight and obesity-related diseases by their PAFs.Results:The disease burden attributable to overweight was 827.1 person years (PYs) overall, 732.6 for men, 922.9 for women per 100u2009000 persons. The disease burden attributable to obesity was 260.0u2009PYs overall, 144.2 for men, 377.3 for women. Diabetes attributable to overweight and obesity accounts for highest burden among other diseases in both genders. The disease burden attributable to overweight was 3.2 times higher than that attributable to obesity.Conclusion:Most proportion of disease burden attributable to high body mass index (BMI) occurred among those with only moderately raised levels such as overweight, not the extremes such as obesity. It suggests that population-based, public health intervention rather than high-risk group-focused strategies are more effective to reduce the burden of disease attributable to overweight and obesity in Korea.

A 35-60 GHz single-pole double-throw(SPDT) switching circuit using direct contact MEMS switches and double resonance technique

In this paper, a single-pole double-throw(SPDT) switching circuit was demonstrated using direct contact MEMS switches and double resonance technique for Q-band and V-band applications. The size of the fabricated SPDT switching circuit is about 1 mm/spl times/2 mm. The direct contact MEMS switches are formed on the CPW transmission lines and actuated with electrostatic force. The fabricated single-pole single-throw(SPST) MEMS switch shows the insertion loss of 0.34 dB and the isolation of 15.5 dB at 50 GHz, respectively. The responses of the fabricated SPDT switching circuit were measured with the frequencies from 0 to 100 GHz. The insertion loss is below 1 dB and isolation is better than 19 dB from 35 GHz to 60 GHz. At the center frequency of 47 GHz, the insertion loss is measured 0.45 dB and isolation is 22 dB. The actuation voltage of the switch is 35V.

Tunable Plasmonic Cavity for Label-free Detection of Small Molecules

Owing to its high sensitivity and high selectivity along with rapid response time, plasmonic detection has gained considerable interest in a wide variety of sensing applications. To improve the fieldwork applicability and reliability of plasmonic detection, the integration of plasmonic nanoparticles into optical devices is desirable. Herein, we propose an integrated label-free detection platform comprising a plasmonic cavity that allows sensitive molecular detection via either surface-enhanced Raman scattering (SERS) or plasmon resonance energy transfer (PRET). A small droplet of metal ion solution spontaneously produces a plasmonic cavity on the surface of uncured poly(dimethylsiloxane) (PDMS), and as PDMS is cured, the metal ions are reduced to form a plasmonic antennae array on the cavity surface. Unique spherical feature and the integrated metallic nanoparticles of the cavity provide excellent optical functions to focus the incident light in the cavity and to rescatter the light absorbed by the nanoparticles. The optical properties of the plasmonic cavity for SERS or PRET are optimized by controlling the composition, size, and density of the metal nanoparticles. By using the cavity, we accomplish both 1000-fold sensitive detection and real-time monitoring of reactive oxygen species secreted by live cells via PRET. In addition, we achieve sensitive detection of trace amounts of toxic environmental molecules such as 5-chloro-2-methyl-4-isothiazolin-3-one/2-methyl-4-isothiazol-3-one (CMIT/MIT) and bisphenol A, as well as several small biomolecules such as glucose, adenine, and tryptophan, via SERS.

MEMS for TPMS and exhaust of automobiles

In this paper, MEMS devices for TPMS and exhaust monitoring of automobiles are investigated. To counteract to EURO6 regulation, particulate matter sensor for detecting DPF failure of diesel engine as well as accelerometers for calibrating centrifugal effect on pressure measurement and secondary energy harvesting device will have strong effect for car safety. Heater embedded PM sensor uses electro dynamic principle and achieves resolution of 0.25mg/km. The accelerometer for TPMS application focuses on simplicity and low cost using piezoresistive beams and anodic bonding. Electrostatic energy harvester uses only 3 masks and shows symmetrical output of up to 0.73uW/cm3.

Determination of nanomolar levels of reactive oxygen species in microorganisms and aquatic environments using a single nanoparticle-based optical sensor

Reactive oxygen species (ROS) are strong oxidants, and have attracted considerable attention in both biological and environmental fields. Although various methods for ROS detection, including optical and electrochemical techniques, have been developed, they still face challenging issues in terms of poor sensitivity, reproducibility, stability, and inxa0vivo applicability. Here, we present a sensitive and selective optical sensor for ROS detection, based on single plasmonic nanoprobes and redox-active cytochrome c (Cyt c)-mediated plasmon resonance energy transfer. By measuring the spectral changes of plasmonic nanoprobes, derived from the unique molecular absorption of Cyt c in accordance with the redox state, calibration curves for H2O2, a representative ROS, in various media were obtained over a wide concentration range from 100xa0mM to 1xa0nM. Limit of detection and limit of quantification in accordance with the used medium were determined from 8.3 to 12.8xa0nM and from 27.6 to 42.7xa0nM, respectively. Selectivity coefficients for major interfering solutes were much lower than 0.1 indicating a good selectivity for ROS. From the dynamic spectral changes, we sensitively monitored ROS generated in Caenorhabditis elegans (C.xa0elegans) exposed to graphene oxide. Based on the calibration curves, we also determined ROS levels in various aquatic environments, such as river streams and a small pond, as a way of environmental monitoring. We believe that our approach could provide an avenue for achieving dynamic and sensitive monitoring of ROS in toxicological, biological, and environmental fields in the future.