Sun Hyok Chung

  • Citations Per Year
Learn More
This study was performed to investigate the etiologic agents, age distribution, clinical manifestations and seasonal occurrence of acute viral lower respiratory tract infections in children. We confirmed viral etiologies using nasopharyngeal aspirates in 237 patients of the ages of 15 years or younger who were hospitalized for acute lower respiratory tract(More)
Pulsed-current controlled wall motion in 20 m wide 200 m long 160 nm thick patterned Permalloy strips was studied using magnetic force microscopy. By sequential imaging, the displacement of Bloch walls as far as 200 m along the strip was observed. The direction of motion was in the same direction as the carrier velocity, which reversed with current(More)
We show that ballistic magnetoresistance exhibits universal scaling in atomic or nanometer scale contacts. Plotting the data as conductance, we find that, if the maximum magnetoconductance is normalized to unity and the conductance is scaled with the conductivity of the bulk material, the data fall in a narrow region, independent of the nanocontact(More)
A commercial atomic force microscope/magnetic force microscope ~MFM! was modified to cool magnetic samples down to around 100 K under a high vacuum while maintaining its routine imaging functionality. MFM images of a 120 nm thick La0.7Ca0.3MnO3 film on a LaAlO3 substrate at low temperature show the paramagnetic-to-ferromagnetic phase transition. Evolution(More)
The dependence on nickel oxide thickness in unidirectional and isotropic exchange-coupled NiO/NiFe bilayer films was investigated by magnetic force microscopy to better understand exchange biasing at microscopic length scales. As the NiO thickness increased, the domain structure of unidirectional biased films formed smaller and more complex inplane domains.(More)
We present results of half-metallic ferromagnets formed by atomic nanocontact of CrO2 – CrO2 and CrO2 – Ni that show as much as 400% magnetoconductance. Analysis of the magnetoconductance versus conductance data for all materials known to exhibit so-called ballistic magnetoresistance strongly suggests that the magnetoconductance of nanocontacts follows(More)
We experimentally demonstrate transmission of 6 x 86 Gb/s DQPSK signals over 2 km of OM2 grade multimode fiber. The successful transmission of 86 Gb/s per wavelength over multimode fiber is the highest speed per wavelength ever reported to our knowledge. The transmission performance over OM2 grade multimode fiber is also compared with OM3 grade multimode(More)
Both ferromagnetic (FM) and charge-ordered domain structures of (La1 Pr )0 67Ca0 33MnO3 thin film were detected by magnetic force microscopy (MFM) and electric force microscopy (EFM) operated at low temperatures near the peak resistance temperature ( ). The in-plane-like FM domains of submicrometer size emerge below , and their magnetic interaction with an(More)
  • 1