• Wind and Structures
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• v.23 no.6
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• pp.615-639
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• 2016

Although the underlying mechanism of rain-wind induced vibrations (RWIVs) of stay cables has not been fully understood, some countermeasures have been successfully applied to mitigating this kind of vibration. Among these, installing dampers near the bridge deck was widely adopted, and several field observations have shown its effectiveness. In this study, the effectiveness of dampers to RWIVs of stay cables is numerically investigated comprehensively by means of finite difference method (FDM). Based on the free vibration analysis of a taut string, it is found that the 3-points triangle scheme, which can be easily implemented in FDM, can offer an excellent approximation of the concentrated damping coefficient (expressed as a Dirac delta function) at the location where the damper is installed. Then, free vibration analysis of a 3-D continuous stay cable attached with two dampers is carried out to study the relationship of modal damping ratio and damping coefficient of the dampers. The effects of orientation of the dampers and cable sag on the modal damping ratio are investigated in detail. Finally, the RWIV response of a 3-D continuous stay cable attached with two dampers is examined. The results indicate that 0.5% of damping ratio is sufficient to reduce the RWIV vibration of the Cable A20 on the No.2 Nanjing Bridge over Yangtze River.

• The Journal of the Korea Contents Association
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• v.18 no.10
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• pp.134-144
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• 2018

The purpose of this study was to examine the effects of delirium prevention program in patients after hip joint surgey. A non equivalent control group post-test only design was utilized. Sixty four patients aged 65 and older who admitted to a surgical intensive care unit after hip joint surgery were assigned to either a experimental group (n=33) or a control group (n=31). The experimental group was provided with delirium prevention program consisting of orientation intervention, activity intervention, physiological intervention, nutritional intervention, sleep intervention, environmental intervention. Data were analyzed using ${\chi}^2-test$ and independent t-test. The experimental group showed lower incidence of delirium than the control group(${\chi}^2=7.048$, p=.008). The experimental group showed lower ICU stay and length of hospitalization than the control group although the difference was not statistically significant. Findings indicate that the dilirium prevention program is effective in reducing incidence of delirium in patients after hip joint surgery and delirium prevention program is recommended as a guide for the prevention of delirium.

• The Journal of Information Systems
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• v.22 no.4
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• pp.23-48
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• 2013

This study shows that a sustainable competitive advantage and entrepreneurial characteristics are necessary for a software company to achieve competitive innovation and growth. This study investigates various software company characteristics and the effects of various company factors as its main research objectives. The data used in this research model were collected from software companies in South Korea. A total of 211 questionnaires were collected over a period of two months in 2013. EXCEL, AMOS, and SPSS were used to derive the study results. The hypothesis testing results of this study are as follows. First, a software company's entrepreneurial innovativeness and risk-taking behaviors have a positive influence on software innovativeness. A greater sense of innovativeness and entrepreneurial orientation leads to a higher propensity to take risks in software development. Second, the characteristics of software innovativeness, and flexibility have a significant influence on software company performance. Innovation during the initial periods of software usage can create a high demand for improvements and new features, requiring a flexible software design. Finally, this study analyzes the software features of entrepreneurial characteristics and the influence of institutional factors on the characteristics of individual innovativeness and software development. Entrepreneurial characteristics can affect governmental or institutional support, policies, and legal frameworks to promote the role of software innovativeness. The results of this study imply that software companies can adopt an entrepreneurial approach to promote technology development and product development for achieving a competitive advantage in the industry. This study also analyzes the environmental factors that affect the software industry and their implications for policy makers.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.19-27
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• 1993

Recent work in the mechanics of fracture points out the desirability of a knowledge of the elastic energy release rate, the crack extension force, and the character of the stress field surrounding a crack tip in analyzing the strength of cracked bodies. The objective of this work is to provide a discussion of the energy rates, stress fields and the like of various cases for anisotropic elastic bodies which might be of interest. Reinforced concrete, wood, laminates, and some special types of elastic bodies with controlled grain orientation are often orthotropic. In this paper, determination of the stress intensity factors(SIFs) of orthotropic plane elastic body using crack tip singular element and fine mesh in near the crack tip is performed. A numerical method in this paper was used by displacement correlation method. A numerical example problem of an orthotropic cantilevered single edge cracked elastic body subjected to shear loading was analyzed, and the results of this paper are in good agreement with those of the others.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.687-690
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• 2002

Multimode boundary-layer transition on a NACA0012 airfoil is experimentally investigated under periodically passing wakes and the moderate level of free-stream turbulence. The periodic wakes are generated by rotating circular cylinders clockwise or counterclockwise around the airfoil. The free-stream turbulence is produced by a grid upstream of the rotating cylinder, and its intensity(Tu) at the leading edge of the airfoil is $0.5\;or\;3.5\;{\%}$. The Reynolds number ($Re_c$) based on chord length (C) of the alrfoil is $2.0{\times}10^5$, and Strouhal number ($St_c$) of the passing wake is about 0.7. Time- and phase-averaged streamwise mean velocities and turbulence fluctuations are measured with a single hot-wire probe, and especially, the corresponding wall skin friction is evaluated using a computational Preston tube method. The wake-passing orientation changes pressure distribution on the airfoil in a different manner irrespective of the free-stream turbulence. Regardless of free-stream turbulence level, turbulent patches for the receding wakes propagate more rapidly than those for the approaching wake because adverse pressure gradient becomes larger. The patch under the high free-stream turbulence ($Tu=3.5{\%}$) grows more greatly in laminar-like regions compared with that under the low background turbulence ($Tu=0.5{\%}$) in laminar regions. The former, however, does not greatly change the original turbulence level in the very near-wall region while the latter does it. At further downstream, the former interacts vigorously with high environmental turbulence inside the pre-existing transitional boundary layer and gradually lose his identification, whereas the latter keep growing in the laminar boundary layer. The calmed region is more clearly observed under the lower free-stream turbulence level and for the receding wakes. The calmed region delays the breakdown further downstream and stabilizes more the boundary layer.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.25 no.2
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• pp.109-119
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• 2018

Purpose: The purpose of this study was to investigate the effects of a delirium prevention intervention for patients in neurology and neurosurgery intensive care units (ICUs). Methods: This study was a quasi-experimental study. Participants were 87 patients. The experimental group was provided with nonpharmacologic and multicomponent delirium prevention interventions, consisting of regular delirium assessment, improvement in orientation, early therapeutic intervention, and environmental interventions. The control group was provided with routine intensive care. Data were analyzed using $x^2$ test, Fisher's exact test, and t-test. Results: Both groups were homogeneous. The incidence of delirium and length of hospitalization were significantly lower in the experimental group compared to the control group. ICU stay, mortality and unplanned extubation were lower in the experimental group compared to the control group, but there was no significant difference. Conclusion: Findings indicate that the delirium prevention intervention is effective in reducing incidence of delirium and length of hospitalization. Therefore, this intervention should be helpful in preventing delirium in neurology and neurosurgery ICUs and can be used as a guide in the prevention of delirium in neurological diseases's patients.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5D
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• pp.641-648
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• 2011

During practices of traffic management, the performance achieved was determined by traffic practitioners' ability of decision and knowledge as well as traffic equipments assisting the practitioners. Therefore, sometimes self-evaluations done by the traffic practitioners in a specific traffic organization can be used to indirectly evaluate the traffic management organization. The present paper is to evaluate a specific highway agency using self-evaluations performed among different highway agencies including one Japanese highway agency. The result indicated that the agency is superior to other agencies in characteristics such as performance, activity, preparation for the future, and customer orientation. For more detailed-branch based study, the responders were divided into their belonged branches like headquarter, regional headquarter, maintenance office and research center. The results provided that various deficiencies of traffic management were found and could be improved in the future.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.3
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• pp.42-52
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• 2010

The purpose of this study is to produce digital elevation model (DEM) in the Jebu tidal flat, one of the west coast of the Korean Peninsula, by means of photogrammetric techniques from aerial digital stereo-images. Produced DEM would be become the fundamental data for change detection of the sediment and erosion. To do so, epipolar line is established by relative orientation. Area-based matching is then carried out based on this line and matching size according to surface property of tidal flat after a classified image is produced from reflectance and texture of the surface. As the results, DEM generated by the proposed method showed subtle changes in height more precisely than DEM using the fixed matching size and DEM by the commercial S/W in the region, such as tidal flats having few level differences.

• Journal of Korean Society of Steel Construction
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• v.10 no.2 s.35
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• pp.201-209
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• 1998

The presence of elevated temperature can alter significantly the structural response of fibre-reinforced laminated composites. A thermal environment causes degradation in both strength and constitutive properties, particularly in the case of fibre-reinforced polymeric composites. Furthermore, associated thermal expansion, either alone or in combination with mechanically induced deformation, can result in buckling, large deflections, and excessively high stress levels. Consequently, it is often imperative to consider environmental effects in the analysis and design of laminated systems. Exact analytical solutions of higher-order shear deformation theory is developed to study the thermal buckling of cross-ply and antisymmetric angle-ply rectangular plates. The buckling behavior of moderately thick cross-ply and antisymmetric angle-ply laminates that are simply supported and subject to a uniform temperature rise is analyzed. Numerical results are presented for fiber-reinforced laminates and show the effects of ply orientation, number of layers, plate thickness, and aspects ratio on the critical buckling temperature and compared with those obtained using the classical and first-order shear deformation theory.

• Journal of Korean Society on Water Environment
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• v.36 no.1
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• pp.36-47
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• 2020

Three large scale weirs were constructed 2010 - 2011 in the Namhan river, Korea. The purpose of this study was to investigate the spatial distribution of benthic macroinvertebrates and the influence of environmental factors at the weirs 2014 - 2015. The number of species was higher in the riparian zone than in the transition or the limnetic zone. This seems to be because of the diversification of microhabitats and food sources according to the development of littoral zones. From the riparian zone to the limnetic zone, the individual abundance proportion of gathering collectors among functional feeding groups decreased, and that of filtering collectors increased. In the limnetic zone, sprawlers and climbers among habitat orientation groups decreased, and burrowers increased. This means that coarse particulate organic matter originated from land or riparian zone was transformed to fine particulate organic matter in the limnetic zone. Asian clam (Corbicula fluminea) and chironomids were dominant species based on individual abundance. Asian clam, a major taxon considering biomass, was abundant toward the limnetic zone. This is becasue of the shallow depth, suitable water current, slightly coarse substrate, and good water quality. There was no significant relationship between the water quality and the characteristics of the benthic macroinvertebrate community because the water quality was spatially not heterogenous. The more influential factors for benthic community were physical factors, especially water depth. Water depth showed a markedly significant correlation with Shannon-Weaver's species diversity (r=-0.90), Margalef's species richness (r=-0.82), and McNaughton's dominance (r=0.86). Water depth showed a positive correlation (r=0.68) with the Kong and Kim BMSI (Bentic Macroinverebrates Streambed Index), and this may be related to the coarse substrate of the limnetic zone.