Korea University

About: Korea University is a education organization based out in Seoul, South Korea. It is known for research contribution in the topics: Population & Catalysis. The organization has 39756 authors who have published 82424 publications receiving 1860927 citations. The organization is also known as: Bosung College & Bosung Professional College.

High prevalence of multidrug-resistant nonfermenters in hospital-acquired pneumonia in Asia.

Abstract: Rationale: Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) remain important causes of morbidity and mortality. Increasing antimicrobial resistance has aroused the concern of the failure of antibiotic treatment.Objectives: To determine the distribution of the bacterial isolates of HAP and VAP, their antimicrobial resistance patterns, and impact of discordant antibiotic therapy on clinical outcome in Asian countriesMethods: A prospective surveillance study was conducted in 73 hospitals in 10 Asian countries from 2008–2009. A total of 2,554 cases with HAP or VAP in adults were enrolled and 2,445 bacterial isolates were collected from 1,897 cases. Clinical characteristics and antimicrobial resistance profiles were analyzed.Measurement and Main Results: Major bacterial isolates from HAP and VAP cases in Asian countries were Acinetobacter spp., Pseudomonas aeruginosa, Staphylococcus aureus, and Klebsiella pneumoniae. Imipenem resistance rates of Acinetobacter and P. aeruginosa were 6...

Predicting Firms' Corporate Governance Choices: Evidence from Korea

Abstract: In a companion paper, we report evidence that a broad corporate governance index predicts higher share prices for Korean firms. Bernard Black, Hasung Jang and Woochan Kim, Does Corporate Governance Affect Firms' Market Values? Evidence from Korea, 22 Journal of Law, Economics and Organization 366-413 (2006), nearly final version at http://ssrn.com/abstract=311275For our related, subsequent work with panel data on Korean governance, see:Bernard Black and Woochan Kim, The Effect of Board Structure on Firm Value: A Multiple Identification Strategy Approach Using Korean Data (working paper 2008), http://ssrn.com/abstract=968287 (identification of board structure reforms with an increase in firm market value).Bernard Black, Woochan Kim, Hasung Jang and Kyung-Suh Park, How Corporate Governance Affects Firm Value: Evidence on Channels from Korea (working paper 2008), http://ssrn.com/abstract=844744 (channels through which governance may affect firm value).

Complete amplitude and phase control of light using broadband holographic metasurfaces

Abstract: Reconstruction of light profiles with amplitude and phase information, called holography, is an attractive optical technology with various significant applications such as three-dimensional imaging and optical data storage. Subwavelength spatial control of both amplitude and phase of light is an essential requirement for an ideal hologram. However, traditional holographic devices suffer from their restricted capabilities of incomplete modulation in both amplitude and phase of visible light; this results in sacrifice of optical information and undesirable occurrences of critical noises in holographic images. Herein, we have proposed a novel metasurface that is capable of completely controlling both the amplitude and phase profiles of visible light independently with subwavelength spatial resolution. The full, continuous, and broadband control of both amplitude and phase was achieved using X-shaped meta-atoms based on the expanded concept of the Pancharatnam-Berry phase. The first experimental demonstrations of the complete complex-amplitude holograms with subwavelength definition at visible wavelengths were achieved, and excellent performances with a remarkable signal-to-noise ratio as compared to those of traditional phase-only holograms were obtained. Extraordinary control capability with versatile advantages of our metasurface paves a way to an ideal holography, which is expected to be a significant advancement in the field of optical holography and metasurfaces.

High-Performance Next-Generation Perovskite Nanocrystal Scintillator for Nondestructive X-Ray Imaging

Abstract: Readily commercializable and cost-effective next-generation CsPbBr3 perovskite nanocrystals (PNCs) based X-ray detectors are demonstrated. The PNCs-based X-ray detector exhibits higher spatial resolution (9.8 lp mm-1 at modulation transfer function (MTF) = 0.2 and 12.5-8.9 lp mm-1 for a linear line chart), faster response time (≈200 ns), and comparable stability (>40 Gyair s-1 of X-ray exposure) compared with the commercialized terbium-doped gadolinium oxysulfide (GOS)-based detectors (spatial resolution = 6.2 lp mm-1 at MTF = 0.2 and 6.3 lp mm-1 for a linear line chart, response time = ≈1200 ns) because the PNCs-based scintillator has ≈5.6-fold faster average photoluminescence lifetime and stronger emission than the GOS-based one.