Kyungpook National University

About: Kyungpook National University is a education organization based out in Daegu, South Korea. It is known for research contribution in the topics: Population & Catalysis. The organization has 20497 authors who have published 42107 publications receiving 834608 citations.

Search for supersymmetry in hadronic final states using MT2 in pp collisions at √s = 7 TeV

Abstract: A search for supersymmetry or other new physics resulting in similar final states is presented using a data sample of 4.73 inverse femtobarns of pp collisions collected at sqrt(s)=7 TeV with the CMS detector at the LHC. Fully hadronic final states are selected based on the variable MT2, an extension of the transverse mass in events with two invisible particles. Two complementary studies are performed. The first targets the region of parameter space with medium to high squark and gluino masses, in which the signal can be separated from the standard model backgrounds by a tight requirement on MT2. The second is optimized to be sensitive to events with a light gluino and heavy squarks. In this case, the MT2 requirement is relaxed, but a higher jet multiplicity and at least one b-tagged jet are required. No significant excess of events over the standard model expectations is observed. Exclusion limits are derived for the parameter space of the constrained minimal supersymmetric extension of the standard model, as well as on a variety of simplified model spectra.

Solar water oxidation using nickel-borate coupled BiVO4 photoelectrodes

Abstract: A naturally abundant nickel-borate (Ni–Bi) complex is demonstrated to successfully catalyze the photoelectrochemical (PEC) water oxidation of BiVO4 electrodes at 1.23 VRHE with nearly 100% faradaic efficiency for oxygen evolution. Ni–Bi is electrodeposited (ED) and photodeposited (PD) for varying times on BiVO4 electrodes in the 0.1 M borate electrolyte with 1 mM Ni2+ at pH 9.2. Surprisingly, optimally deposited Ni–Bi films (ED-10 s and PD-30 min) display the same layer thickness of ca. 40 nm. Both Ni–Bi films enhance the photocurrent generation of BiVO4 at 1.23 VRHE by a factor of 3–4 under AM 1.5-light irradiation (100 mW cm−2) along with ca. 250% increase in the incident and absorbed photon-to-current efficiencies. Impedance analysis further reveals that the charge transfer resistance at BiVO4 is markedly decreased by Ni–Bi deposits. The primary role of Ni–Bi has been suggested to be a hole-conductor making photogenerated electrons more mobile and catalyzing a four-hole transfer to water through cyclic changes between the lower and higher Ni oxidation states. However, thick Ni–Bi films (>∼40 nm) significantly reduce the PEC performance of BiVO4 due to the kinetic bottleneck and charge recombination. Under identical PEC conditions (0.1 M, pH 9.2), the borate electrolyte (good proton acceptor) is found to be better than nitrate (poor proton acceptor), indicative of a proton-coupled electron transfer pathway in PEC water oxidation.

Recent trends of mean and extreme precipitation in Korea

Abstract: The spatial and temporal variability of precipitation in Korea were investigated using 183 weather station data for 1973–2005. A set of 16 indices that represent mean and extreme values of precipitation data were estimated using daily precipitation data, linear and spatial trend relationships of the indices were analysed using the Mann–Kendall test and Moran's I test statistic, respectively. Results demonstrate that annual precipitation data have a significant positive trend and there is a strong spatial relationship in their variability. The increase of annual precipitation is mainly associated with the increase of frequency and intensity of heavy precipitation during summer season. However, precipitation during spring and winter seasons had a decreasing trend. This variation of precipitation is likely to increase flood and drought risk. It means that the increase of annual precipitation should not be helpful for water resources management but could be a burden to river management and dam operation in Korea. Copyright © 2010 Royal Meteorological Society

Observation of Anomalous Υ(1S)π + π - and Υ(2S)π + π - Production near the Υ(5S) Resonance

Abstract: Reference EPFL-ARTICLE-154550doi:10.1103/PhysRevLett.100.112001View record in Web of Science Record created on 2010-11-05, modified on 2017-12-10