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Lee H.-S.,Korea Advanced Institute of Science and Technology | Ryu K.-S.,Korea Advanced Institute of Science and Technology | Kang I.-S.,Korea Science Academy | Shin S.-C.,Korea Advanced Institute of Science and Technology
Journal of Applied Physics | Year: 2011

We have investigated the Barkhausen critical scaling behavior of Ni xFe 1-x (x 0-0.5) films using a magneto-optical microscope, capable of time-resolved domain observation. Real-time direct observations of the domain evolutions in these films revealed that magnetization reversal occurred with a sequence of random Barkhausen jumps. From more than 1000 repeated experiments with each sample, it was found that the distribution of the Barkhausen jump size followed a power-law distribution. The scaling exponent of the power-law distribution was found to have the same value of 1.1, independent of the film composition, revealing a universal critical scaling behavior in these alloy films. © 2011 American Institute of Physics. Source


Bae D.S.,Changwon National University | Bae D.S.,Korea Science Academy
IOP Conference Series: Materials Science and Engineering | Year: 2013

Iron doped TiO2 nanoparticles were prepared under the high temperature and pressure conditions by mixture of metal nitrates solution and TiO2 sol. Fe doped TiO2 particles were reaction at the temperature range of 170°C-200°C for 6 h. The microstructure and phase of synthesized particles were studied by SEM(FE-SEM), TEM and XRD. Thermal properties of the synthesized particles were investigated by TG-DTA analysis. Also, Specific Surface Area of synthesized particles were studied by BET analysis. X-ray diffraction pattern shows that the synthesized particles shows the coexistence of anatase and rutile reaction at the temperature range of 170°C to 200°C for 6 h. The amount of rutile phase on the synthesized particles increased with decreasing Ag concentration in solution because the less a content of the transposition metal, the easier to phase transition in the same temperature condition. The average size and distribution of the synthesized particles was about 10nm and narrow, respectively. The average size of the synthesized particles increased as reaction temperature increased. Also, BET surface areas of synthesized particles by a hydrothermal process were found to be larger than that of pure TiO2 which is synthesized by a sol-gel process. © Published under licence by IOP Publishing Ltd. Source


Choi H.J.,Pusan National University | Ahn J.H.,Korea Science Academy | Park S.-H.,Pusan National University | Do K.H.,Pusan National University | And 2 more authors.
Infection and Immunity | Year: 2012

The gastrointestinal mucosa has a remarkable ability to repair damage with the support of epidermal growth factor (EGF), which stimulates epithelial migration and proliferative reepithelialization. For the treatment of mucosal injuries, it is important to develop efficient methods for the localized delivery of mucoactive biotherapeutics. The basic idea in the present study came from the assumption that an intestinal probiotic vehicle can carry and deliver key recombinant medicinal proteins to the injured epithelial target in patients with intestinal ulcerative diseases, including inflammatory bowel disease. The study was focused on the use of the safe probiotic E. coli Nissle 1917, which was constructed to secrete human EGF in conjunction with the lipase ABC transporter recognition domain (LARD). Using the in vitro physically wounded monolayer model, ABC transporter-mediated EGF secretion by probiotic E. coli Nissle 1917 was demonstrated to enhance the wound-healing migration of human enterocytes. Moreover, the epithelial wound closure was dependent on EGF receptor-linked activation, which exclusively involved the subsequent signaling pathway of the mitogen-activated protein kinase kinase (MEK) extracellular-related kinases 1 and 2 (ERK1/2). In particular, the migrating frontier of the wounded edge displayed the strongest EGF receptor-linked signaling activation in the presence of the recombinant probiotic. The present study provides a basis for the clinical application of human recombinant biotherapeutics via an efficient, safe probiotic vehicle. © 2012, American Society for Microbiology. Source


Phanikumar D.V.,Aryabhatta Research Institute of Observational science | Kwak Y.-S.,Korea Astronomy and Space Science Institute | Patra A.K.,National Atmospheric Research Laboratory | Maurya A.K.,KSK Geomagnetic Research Laboratory | And 2 more authors.
Advances in Space Research | Year: 2014

In this paper, we analyze VLF signals received at Busan to study the the D-region changes linked with the solar eclipse event of 22 July 2009 for very short (∼390 km) transmitter-receiver great circle path (TRGCP) during local noon time 00:36-03:13 UT (09:36-12:13 KST). The eclipse crossed south of Busan with a maximum obscuration of ∼84%. Observations clearly show a reduction of ∼6.2 dB in the VLF signal strength at the time of maximum solar obscuration (84% at 01:53 UT) as compared to those observed on the control days. Estimated values of change in Wait ionospheric parameters: reflection height (h′) in km and inverse scale height parameter (β) in km-1 from Long Wave Propagation Capability (LWPC) model during the maximum eclipse phase as compared to unperturbed ionosphere are 7 km and 0.055 km-1, respectively. Moreover, the D-region electron density estimated from model computation shows 95% depletion in electron density at the height of ∼71 km. The reflection height is found to increase by ∼7 km in the D-region during the eclipse as compared to those on the control days, implying a depletion in the Lyman-α flux by a factor of ∼7. The present observations are discussed in the light of current understanding on the solar eclipse induced D-region dynamics. © 2014 COSPAR. Published by Elsevier Ltd. All rights reserved. Source


Huang J.Y.,Pohang Accelerator Laboratory | Jin K.S.,Pohang Accelerator Laboratory | Lim J.H.,Pohang Accelerator Laboratory | Kim H.Y.,Pohang Accelerator Laboratory | And 4 more authors.
Journal of the Korean Physical Society | Year: 2010

Since Roentgen's discovery of X-ray, X-ray imaging technique has been the most important medical diagnosis tool for more than a century. Though there has been remarkable progress in X-ray imaging techniques, the contrast and the resolution of conventional X-ray imaging have been limited due to the weak absorption contrast of X-rays in bio-medical matter. However, as partially coherent synchrotron X-ray radiation and high-resolution detectors are now available, it is possible to get high-resolution phase-contrast X-ray images of bio-medical tissue in 3rd generation synchrotron light sources. In the Pohang Light Source (PLS), there are two X-ray microscopy beamlines operating for public users: the 1B2 beamline dedicated to high-resolution phase-contrast microscopy, and the 7B2 beamline for lensless white-beam micro-tomography. In this paper, we report phase-contrast X-ray imaging techniques and their applications in the PLS. Source

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