Showing papers by "Pusan National University published in 2003"
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TL;DR: Time-resolved mid-infrared spectroscopy of flash-photolyzed L29F MbCO revealed a short-lived CO intermediate whose 140-ps lifetime is shorter than that found in wild-type protein by a factor of 1000.
Abstract: We report picosecond time-resolved x-ray diffraction from the myoglobin (Mb) mutant in which Leu29 is replaced by Phe (L29Fmutant). The frame-by-frame structural evolution, resolved to 1.8 angstroms, allows one to literally "watch" the protein as it executes its function. Time-resolved mid-infrared spectroscopy of flash-photolyzed L29F MbCO revealed a short-lived CO intermediate whose 140-ps lifetime is shorter than that found in wild-type protein by a factor of 1000. The electron density maps of the protein unveil transient conformational changes far more dramatic than the structural differences between the carboxy and deoxy states and depict the correlated side-chain motion responsible for rapidly sweeping CO away from its primary docking site.
736 citations
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Osaka University1, Pusan National University2, Konan University3, Japan Atomic Energy Agency4, Academia Sinica5, Seoul National University6, Ohio University7, Kyoto University8, Tohoku University9, Yamagata University10, Chiba University11, Wakayama Medical University12, Tokyo Institute of Technology13, Nagoya University14, University of Saskatchewan15, University of Minnesota16, University of Michigan17
TL;DR: The gamman-->K(+)K(-)n reaction on 12C has been studied by measuring both K+ and K- at forward angles and a sharp baryon resonance peak was observed, consistent with an antidecuplet of baryons predicted by the chiral soliton model.
Abstract: The $\ensuremath{\gamma}n\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}n$ reaction on $^{12}\mathrm{C}$ has been studied by measuring both ${K}^{+}$ and ${K}^{\ensuremath{-}}$ at forward angles. A sharp baryon resonance peak was observed at $1.54\ifmmode\pm\else\textpm\fi{}0.01\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V}/{c}^{2}$ with a width smaller than $25\text{ }\text{ }\mathrm{M}\mathrm{e}\mathrm{V}/{c}^{2}$ and a Gaussian significance of $4.6\ensuremath{\sigma}$. The strangeness quantum number ($S$) of the baryon resonance is $+1$. It can be interpreted as a molecular meson-baryon resonance or alternatively as an exotic five-quark state ($uudd\overline{s}$) that decays into a ${K}^{+}$ and a neutron. The resonance is consistent with the lowest member of an antidecuplet of baryons predicted by the chiral soliton model.
691 citations
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TL;DR: In this article, the authors studied the properties of cosmological shock waves identified in high-resolution, N-body/hydrodynamic simulations of a ΛCDM universe and their role on thermalization of gas and acceleration of nonthermal, cosmic-ray (CR) particles.
Abstract: We study the properties of cosmological shock waves identified in high-resolution, N-body/hydrodynamic simulations of a ΛCDM universe and their role on thermalization of gas and acceleration of nonthermal, cosmic-ray (CR) particles. External shocks form around sheets, filaments, and knots of mass distribution when the gas in void regions accretes onto them. Within those nonlinear structures, internal shocks are produced by infall of previously shocked gas to filaments and knots and during subclump mergers, as well as by chaotic flow motions. Due to the low temperature of the accreting gas, the Mach number of external shocks is high, extending up to M ~ 100 or higher. In contrast, internal shocks have mostly low Mach numbers. For all shocks of M ≥ 1.5, the mean distance between shock surfaces over the entire computed volume is ~4 h-1 Mpc at present, or ~1 h-1 Mpc for internal shocks within nonlinear structures. Identified external shocks are more extensive, with their surface area ~2 times larger than that of identified internal shocks at present. However, especially because of higher preshock densities but also due to higher shock speeds, internal shocks dissipate more energy. Hence, the internal shocks are mainly responsible for gas thermalization as well as CR acceleration. In fact, internal shocks with 2 M 4 contribute about one-half of the total dissipation. Using a nonlinear diffusive shock acceleration model for CR protons, we estimate the ratio of CR energy to gas thermal energy dissipated at cosmological shock waves to be about one-half through the history of the universe. Our result supports scenarios in which the intracluster medium contains energetically significant populations of CRs.
499 citations
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TL;DR: SSeCKS regulates BBB differentiation by modulating both brain angiogenesis and tight junction formation, which suggests that BBB maintenance is important in the central nervous system (CNS).
Abstract: The blood-brain barrier (BBB) is essential for maintaining brain homeostasis and low permeability. BBB maintenance is important in the central nervous system (CNS) because disruption of the BBB may contribute to many brain disorders, including Alzheimer disease and ischemic stroke. The molecular mechanisms of BBB development remain ill-defined, however. Here we report that src-suppressed C-kinase substrate (SSeCKS) decreases the expression of vascular endothelial growth factor (VEGF) through AP-1 reduction and stimulates expression of angiopoietin-1 (Ang-1), an antipermeability factor in astrocytes. Conditioned media from SSeCKS-overexpressing astrocytes (SSeCKS-CM) blocked angiogenesis in vivo and in vitro. Moreover, SSeCKS-CM increased tight junction proteins in endothelial cells, consequently decreasing [3H]sucrose permeability. Furthermore, immunoreactivity to SSeCKS gradually increased during the BBB maturation period, and SSeCKS-expressing astrocytes closely interacted with zonula occludens (ZO)-1-expressing blood vessels in vivo. Collectively, our results suggest that SSeCKS regulates BBB differentiation by modulating both brain angiogenesis and tight junction formation.
468 citations
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TL;DR: In this paper, the effect of clay contents on the tensile, dynamic mechanical, and thermal properties as well as the barrier properties of the nanocomposites were investigated using wide angle X-ray diffraction and transmission electron microscopy (TEM).
Abstract: As an attempt to develop environmentally friendly polymer hybrids, biodegradable thermoplastic starch (TPS)/clay nanocomposites were prepared through melt intercalation method. Natural montrorillonite (Na+ MMT; Cloisite Na+) and one organically modified MMT with methyl tallow bis-2-hydroxyethyl ammonium cations located in the silicate gallery (Cloisite 30B) were chosen in the nanocomposite preparation. TPS was prepared from natural potato starch by gelatinizing and plasticizing it with water and glycerol. The dispersion of the silicate layers in the TPS hybrids was characterized by using wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). It was observed that the TPS/Cloisite Na+ nanocomposites showed higher tensile strength and thermal stability, better barrier properties to water vapor than the TPS/Cloisite 30B nanocomposites as well as the pristine TPS, due to the formation of the intercalated nanostructure. The effect of clay contents on the tensile, dynamic mechanical, and thermal properties as well as the barrier properties of the nanocomposites were investigated.
442 citations
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TL;DR: In this paper, a mixed-integer-linear-programming (MIP) model was formulated for the berth-scheduling problem and a simulated annealing algorithm was applied to the berth scheduling problem to find near-optimal solutions.
Abstract: The objective of the berth-scheduling problem is to determine the berthing times and positions of containerships in port container terminals. Every vessel requires a specific amount of space in a wharf for a predetermined length of time to unload and load containers. In this study, a mixed-integer-linear-programming (MIP) model was formulated for the berth-scheduling problem. The simulated annealing algorithm was applied to the berth-scheduling problem to find near-optimal solutions. Experimental results showed that the simulated annealing algorithm obtains solutions that are similar to the optimal solutions found by the MIP model.
391 citations
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TL;DR: The data indicate that transplanted hATSCs survive, migrate, and improve functional recovery after stroke and that genetically engineered h ATSCs can express biologically active gene products and, therefore, can function as effective vehicles for therapeutic gene transfer to the brain.
381 citations
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TL;DR: The qualitative and quantitative differences in the cellular wound healing response after PRK for high and low myopia and LASIK for high myopia are likely determinants of the clinical differences in refractive outcome and some of the complications, such as regression and haze, seen after these procedures.
376 citations
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TL;DR: In this article, a single-phase five-level PWM inverter is presented to alleviate harmonic components of the output voltage and the load current, and the deadbeat controller is designed and implemented on a prototype.
Abstract: A single-phase five-level PWM inverter is presented to alleviate harmonic components of the output voltage and the load current. Operational principles with switching functions are analyzed. To keep the output voltage sinusoidal and to have the high dynamic performances even in the cases of load variations and the partial magnetization in filter inductor, the deadbeat controller is designed and implemented on a prototype. The validity of the proposed inverter is verified through simulation and experiments. To assess the proposed inverter, it is compared with the conventional single-phase three-level PWM inverter under the conditions of identical supply DC voltage and switching frequency. In addition, it is compared with the five-level cascaded PWM inverter.
334 citations
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TL;DR: This paper discusses a method for scheduling Berth and Quay cranes, which are critical resources in port container terminals, and an integer programming model is formulated by considering various practical constraints.
Abstract: This paper discusses a method for scheduling Berth and Quay cranes, which are critical resources in port container terminals. An integer programming model is formulated by considering various practical constraints. A two-phase solution procedure is suggested for solving the mathematical model. The first phase determines the Berthing position and time of each vessel as well as the number of cranes assigned to each vessel at each time segment. The subgradient optimization technique is applied to obtain a near-optimal solution of the first phase. In the second phase, a detailed schedule for each Quay crane is constructed based on the solution found from the first phase. The dynamic programming technique is applied to solve the problem of the second phase. A numerical experiment was conducted to test the performance of the suggested algorithms.
332 citations
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Goethe University Frankfurt1, Joint Institute for Nuclear Research2, Hungarian Academy of Sciences3, Polish Academy of Sciences4, University of Marburg5, Charles University in Prague6, Université libre de Bruxelles7, Comenius University in Bratislava8, CERN9, Lawrence Berkeley National Laboratory10, University of Washington11, University of Toulouse12, Max Planck Society13, Eötvös Loránd University14, GSI Helmholtz Centre for Heavy Ion Research15, National and Kapodistrian University of Athens16, Jan Kochanowski University17, University of Houston18, University of Paris19, University of Warsaw20, Massachusetts Institute of Technology21, Wayne State University22, Pusan National University23
TL;DR: In this paper, both the standard method of correlating particles with an event plane and the cumulant method of studying multiparticle correlations were used to reconstruct the collective motion in A+A collisions at SPS energies.
Abstract: Directed and elliptic flow measurements for charged pions and protons are reported as a function of transverse momentum, rapidity, and centrality for 40A and 158A GeV Pb+Pb collisions, as recorded by the NA49 detector. Both the standard method of correlating particles with an event plane and the cumulant method of studying multiparticle correlations are used. In the standard method the directed flow is corrected for conservation of momentum. In the cumulant method elliptic flow is reconstructed from genuine four-, six-, and eight-particle correlations, showing the first unequivocal evidence for collective motion in A+A collisions at SPS energies.
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TL;DR: In this paper, aqueous emulsion of polyurethane ionomers, based on poly(tetramethylene glycol) or poly(butylene adipate) as soft segment, isophorone diisocyanate as diiscyanate, 1,4-butandiol as chain extender, dimethyl propionic acid as potential ionic center, triethylene tetramine as crosslinker, and triethyl amine as neutralizer, were reinforced with organoclay to give nanocomposites.
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TL;DR: An antibacterial peptide with 16 amino acid residues was found in plasma of the freshwater crayfish, Pacifastacus leniusculus, and it was purified by cation-exchange column chromatography and reverse-phase high performance liquid chromatography, suggesting that the amino-terminal part of astacidin 1 contributes to the antibacterial activity.
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TL;DR: The overall performance of Citrobacter sp.
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TL;DR: The hypothesis that several strains of Microcystis aeruginosa increased toxin production in response to direct and indirect exposure to herbivorous zooplankton of several species is supported, and support the hypothesis that this response is an induced defence mediated by the release of info-chemicals from zoopLankton.
Abstract: Summary
1. Cyanobacterial toxin production in response to direct and indirect zooplankton feeding activity was examined using four strains of Microcystis aeruginosa, of which three were previously reported to be toxic to zooplankton and one non-toxic. Direct (Microcystis cultured with zooplankton) and indirect effects (Microcystis cultured with filtered zooplankton culture media, ZCMF) were tested for the zooplankton species, Moina macrocopa, Daphnia magna or D. pulex.
2. With direct exposure to zooplankton, increased mass-specific microcystin productions occurred in all Microcystis strains, with mean microcystin concentrations up to five times greater (61.5–177.3 μg g−1 dry cell) than the controls.
3. With indirect exposure, mass-specific microcystin production increased over controls in three strains of M. aeruginosa. Mean maximum concentrations of microcystin during the experiment were 92.6–125.7 μg g−1 dry cell.
4. These results suggest that several strains of Microcystis aeruginosa increased toxin production in response to direct and indirect exposure to herbivorous zooplankton of several species, and support the hypothesis that this response is an induced defence mediated by the release of info-chemicals from zooplankton.
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TL;DR: This paper discusses how to allocate storage space for outbound containers that will arrive at a storage yard and two heuristic algorithms are suggested based on the duration-of-stay of containers and the sub-gradient optimization technique, respectively.
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TL;DR: In this article, the first preparation of highly ordered large-pore hexagonal periodic mesoporous organosilicas using triblock copolymer P123 as the template and inorganic salts as the auxiliary agents under strongly acidic conditions is described.
Abstract: This communication describes the first preparation of highly ordered large-pore hexagonal periodic mesoporous organosilicas (PMOs) using triblock copolymer P123 as the template and inorganic salts as the auxiliary agents under strongly acidic conditions. The long-range structural order of the PMOs results from the enhanced self-assembly interaction imparted by inorganic salts.
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25 Jun 2003
TL;DR: A linear-time algorithm to construct suffix arrays for integer alphabets, which do not use suffix trees as intermediate data structures during its construction, and implies that the time complexity of directly constructing suffix arrays matches that of constructing suffix trees.
Abstract: The time complexity of suffix tree construction has been shown to be equivalent to that of sorting: O(n) for a constant-size alphabet or an integer alphabet and O(n log n) for a general alphabet. However, previous algorithms for constructing suffix arrays have the time complexity of O(n log n) even for a constant-size alphabet.
In this paper we present a linear-time algorithm to construct suffix arrays for integer alphabets, which do not use suffix trees as intermediate data structures during its construction. Since the case of a constant-size alphabet can be subsumed in that of an integer alphabet, our result implies that the time complexity of directly constructing suffix arrays matches that of constructing suffix trees.
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TL;DR: A disposable and mediatorless immunosensor based on a conducting polymer (5,2':5'2"-terthiophene-3'-carboxylic acid) coated screen-printed carbon electrode has been developed using a separation-free homogeneous technique for the detection of rabbit IgG as a model analyte.
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TL;DR: The stability of the EDTA-CPME was remarkably improved by coating the surface with the Nafion film, and the electrode can be used for more than one month, and it was found that there was little or no effect on the simultaneous determination.
Abstract: An EDTA bonded conducting polymer modified electrode (EDTA-CPME) was fabricated by polymerization of 3',4'-diamino-2,2';5',2''-terthiophene monomer on a GCE, followed by the reaction with EDTA in the presence of catalyst. The surface of the resulting modified electrode was characterized with EQCM, ESCA, SEM, Auger electron spectroscopy, scanning Auger microscopy, and electrochemical methods. The amounts of polymer and EDTA attached on the polymer film were determined. Simple immersing of the EDTA-CPME into a sample solution led to the chemical deposition through the complexation with Pb2+, Cu2+, and Hg2+ ions, simultaniously. Various experimental parameters that affect the simultaneous analysis of the metal ions, e.g., EDTA amount, pH, deposition time, and deposition temperature, were optimized. Calibration plots for the EDTA-CPME with square wave voltammetry were obtained in the concentration range between 5.0 × 10-10 and 1.0 × 10-7 M for Cu(II) and between 7.5 × 10-10 and 1.0 × 10-7 M for Pb(II) and Hg(...
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TL;DR: In this article, a parameter-free calculation of the threshold S factors for the solar and hep processes in an effective field theory (EFT) that combines the merits of the standard nuclear physics method and systematic chiral expansion was carried out.
Abstract: Spurred by the recent complete determination of the weak currents in two-nucleon systems up to $\mathcal{O}{(Q}^{3})$ in heavy-baryon chiral perturbation theory, we carry out a parameter-free calculation of the threshold S factors for the solar $\mathrm{pp}$ (proton-fusion) and hep processes in an effective field theory (EFT) that combines the merits of the standard nuclear physics method and systematic chiral expansion. The power of the EFT adopted here is that one can correlate in a unified formalism the weak-current matrix elements of two-, three-, and four-nucleon systems. Using the tritium $\ensuremath{\beta}$-decay rate as an input to fix the only unknown parameter in the theory, we can evaluate the threshold S factors with drastically improved precision; the results are ${S}_{\mathrm{pp}}(0)=3.94\ifmmode\times\else\texttimes\fi{}(1\ifmmode\pm\else\textpm\fi{}0.004)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}25}\mathrm{MeV}\mathrm{}\mathrm{b}$ and ${S}_{\mathrm{hep}}(0)=(8.6\ifmmode\pm\else\textpm\fi{}1.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}20}\mathrm{keV}\mathrm{}\mathrm{b}.$ The dependence of the calculated S factors on the momentum cutoff parameter $\ensuremath{\Lambda}$ has been examined for a physically reasonable range of $\ensuremath{\Lambda}.$ This dependence is found to be extremely small for the $\mathrm{pp}$ process, and to be within acceptable levels for the hep process, substantiating the consistency of our calculational scheme.
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20 Jul 2003
TL;DR: A new concept using a virtual obstacle is proposed to escape local minimums occurred in local path planning and a sensor based discrete modeling method is proposed for modeling of the mobile robot with range sensors.
Abstract: The artificial potential field (APF) based path planning methods have a local minimum problem, which can trap mobile robots before reaching it's goal. In this study, a new concept using a virtual obstacle is proposed to escape local minimums occurred in local path planning. A virtual obstacle is located around local minimums to repel a mobile robot from local minimums. A sensor based discrete modeling method is also proposed for modeling of the mobile robot with range sensors. This modeling method is adaptable for a real-time path planning because it provides lower complexity.
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TL;DR: A ring R is called reversible if ab = 0 implies ba = 0 for a, b ∈ R, where b is the right quotient ring of R and ab is a positive integer.
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TL;DR: The results indicate that MIC-1 may contribute to the malignant progression of gastric cancer cells by inducing tumor cell invasion through the up-regulation of the uPA activation system via extracellular signal-regulated kinase-1/2-dependent pathway.
Abstract: In our search for genes associated with gastric cancer progression, we identified macrophage inhibitory cytokine-1 (MIC-1), a member of the transforming growth factor β superfamily, as an overexpressed gene in gastric tumor tissues. Expression analysis of MIC-1 in gastric tumor tissues revealed a specific expression in gastric cancer cells, and this expression level was well correlated with invasive potential in various human gastric cancer cell lines. Stable transfection of MIC-1 into SNU-216, a human gastric cancer cell line, significantly increased its invasiveness. The overexpression of MIC-1 into SNU-216 cells significantly increased the activity of urokinase-type plasminogen activator (uPA), and the expressions of uPA and urokinase-type plasminogen activator receptor (uPAR). Similarly, the stimulation of gastric cancer cell lines with purified recombinant MIC-1 dose-dependently increased cell invasiveness, uPA activity, and uPA and uPAR expression. However, MIC-1 did not significantly suppress the proliferation of gastric cancer cell lines. We also found that the stimulation of human gastric cell lines with recombinant MIC-1 strongly induced activation of mitogen-activated protein kinase kinase-1/2 and extracellular signal-regulated kinase-1/2. Additional analysis revealed that PD98059, a selective inhibitor of mitogen-activated protein kinase kinase-1/2, suppressed not only gastric cancer cell invasiveness and uPA activity, but also the mRNA expressions of uPA and uPAR, as induced by recombinant MIC-1. Our results indicate that MIC-1 may contribute to the malignant progression of gastric cancer cells by inducing tumor cell invasion through the up-regulation of the uPA activation system via extracellular signal-regulated kinase-1/2-dependent pathway.
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TL;DR: It is found that a histone deacetylase (HDAC) inhibitor, FK228, inhibits the induction and activity of HIF-1 in response to hypoxia, suggesting that FK 228 contributes to the inhibition of tumor angiogenesis.
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TL;DR: Results suggest that hydrogen peroxide is involved in the cisplatin-induced necrosis, whereas hydroxyl radical is responsible for the cisPlatin- induced apoptosis.
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TL;DR: The HRPmid R:TCAPMid R:GC electrode acted as a sensor and displayed an excellent specific electrocatalytic response to the reduction of H2O2 without the aid of an electron transfer mediator.
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TL;DR: The production of BC by Acetobacter sp.
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TL;DR: This paper considers the production–inventory problem in which the demand, production and deterioration rates of a product are assumed to vary with time, and two models are developed by employing different modeling approaches over an infinite planning horizon.
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TL;DR: Suggestions to reduce the level of burnout include enhancing nurses' cognitive empathy and perceived power, providing clear job descriptions and work expectations, and exploring nurses' shift preferences, especially at tertiary hospitals.
Abstract: Background. Although burnout among nurses has been studied in a great deal, this work has not included Korean nurses. Furthermore, the role of personal resources such as empathy and empowerment in predicting the variance in burnout has never been examined.
Aim. The purpose of this study was to understand the phenomenon of burnout among Korean nurses. A comprehensive model of burnout was examined to identify significant predictors among individual characteristics, job stress and personal resource, with the intention of providing a basis for individual and organizational interventions to reduce levels of burnout experienced by Korean nurses.
Methods. A cross-sectional correlational design was used. A sample of 178 nurses from general hospitals in southern Korea was surveyed from May 1999 to March 2000. The data were collected using paper and pencil self-rating questionnaires and analysed using descriptive statistics, Pearson correlations, and hierarchical multiple regression.
Results. Korean nurses reported higher levels of burnout than nurses in western countries such as Germany, Canada, the United Kingdom and the United States of America. Nurses who experienced higher job stress, showed lower cognitive empathy and empowerment, and worked in night shifts at tertiary hospitals were more likely to experience burnout.
Conclusions. Identifying a comprehensive model of burnout among Korean nurses is an essential step to develop effective managerial strategies to reduce the problem. Suggestions to reduce the level of burnout include enhancing nurses’ cognitive empathy and perceived power, providing clear job descriptions and work expectations, and exploring nurses’ shift preferences, especially at tertiary hospitals. In future research we recommend recruiting nurses from broader geographical areas using random selection in order to increase the generalizability of the findings.