• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.3
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• pp.311-318
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• 2003

The present work evaluates the effects of mixing vane shape on the flow structure and heat transfer downstream of mixing vane in a subchannel of fuel assembly. by obtaining velocity and pressure fields. turbulent intensity. flow-mixing factors. heat transfer coefficient and friction factor using three-dimensional RANS analysis. Four different shapes of mixing vane. which were designed by the authors were tested to evaluate the performances in enhancing the heat transfer. Standard k-$\varepsilon$ model is used as a turbulence closure model. and. periodic and symmetry conditions are set as boundary conditions. The flow blockage ratio is kept constant. but the twist angle of mixing vane is changed. The results with three turbulence models were compared with experimental data.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.6
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• pp.520-529
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• 2015

The ambient $PM_{2.5}$ samples were collected by $PM_{2.5}$ sampler from September 2010 to December 2012 at Daegu University, Gyeongsan. A total of 260 samples were collected and 27 species were analyzed by inductively coupled plasma, ion chromatography, and thermal optical reflectance methods. Factor analysis identified four sources such as biomass burning source/secondary aerosol source, soil source, industry source, and incinerator source/mobile source. Also, backward trajectories were calculated using HYSPLIT 4 (Hybrid single-particle lagrangian integrated trajectory) model and PSCF (Potential source contribution function) model was applied to identify the possible source locations of carbonaceous species and water soluble ions species. PSCF results showed that the possible source locations of most chemical constituents measured in Gyeongsan were the industrial areas in the eastern coast of China, northeast regions of China, the Gobi Desert, and east sea of Korea.

• The Journal of Information Systems
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• v.15 no.2
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• pp.195-226
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• 2006

The purpose of this study is (1) to develop a conceptually integrated model of IT capability comprising hierarchically structured lower capabilities, and (2) to investigate the impacts of IT capability on firm performance. To do this, the study defined IT capability as a third-order factor model and identified three conceptual dimensions of IT capability IT resource integrating capability, IT infrastructure flexibility, and IT personnel expertise. The relationships between IT capability and firm performance are assessed with 243 firm level data using LISREL. The results of confirmatory factor analysis (CFA) demonstrated that the constructs is highly reliable and valid. Further, we found that IT capability not directly but indirectly affects firm performance through the impacts on business processes.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.835-840
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• 2000

The objective of the present study is to investigate the characteristics of pressure wave propagation of viscous fluid flow in a circular pipe line. The goal of this study is to select the best frequency of each control factor of a circular pipe. We intend to approach a formalized mathematical model by a very exact and reasonable polynomial for fluid transmission lines. and we computed this mathematical model by computer. The results show that the oil viscosity decreased as the length of the circular pipe increases. and The energy of pressure wave propagation decreased as the pipe diameter decreases. The factor is that density of oil was changed resonant frequency. It has been found the viscosity characteristics is changed largely by length of hydraulic pipe and volume of cavity tank.

• Proceedings of the Korean Society for Quality Management Conference
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• 2004.04a
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• pp.48-53
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• 2004

As many organizations are searching for ways to compete more effectively in today's market environment. Image of Product is become the most important fact to improve their competition. The objectives of this paper are to provide an overview of PDM(Purchasing Decision Factor) and to discuss how to measure it more efficiently. This study develops a conceptual 'relation model of the purchasing decision factor', which identifies only performance based measurement, and proposes Fuzzy Measuring Method which uses the Fuzzy rule based algorithm to adept survey to date sets.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.12
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• pp.938-946
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• 2003

Length of an unconstrained viscoelastic damping layer on beams is determined to maximizeloss factor using a numerical search method. The fractional derivative model can describe damping characteristics of viscoelastic damping materials accurately, and is used to represent nonlinearity of complex modulus with frequencies and temperatures. Equivalent flexural rigidity of the unconstrained beam is obtained using Ross, Ungar, Kelvin[RUK] equation. The loss factors of partially covered unconstrained beam are calculated by a modal strain energy method. Optimal lengths of the unconstrained viscoelastic damping layer of beams are identified with ambient temperatures and thickness ratios of beam and damping layer by using a finite-difference-based steepest descent method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.665-671
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• 2003

Length of an unconstrained viscoelastic damping layer on beams is determined to maximize loss factor using a numerical search method. The fractional derivative model can describe damping characteristics of the viscoelastic damping material, and is used to represent nonlinearity of complex modulus with frequencies and temperatures. Equivalent flexural rigidity of the unconstrained beam is obtained using Ross, Ungar, Kerwin(RUK) equation. The loss factors of partially covered unconstrained beam are calculated by a modal strain energy method. Optimal lengths of the unconstrained viscoelastic damping layer of beams are obtained with respect to ambient temperatures and thickness ratios of beam and damping layer.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.10
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• pp.1651-1658
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• 2001

It is necessary to evaluate fatigue strength and reliability of the connecting rod which is core part in automotive engine to assure the high level of durability of automobile. For this purpose, the loading conditions in automotive engine is obtained by the dynamic analysis. Based on these results, the critical section was identified by the finite element analysis. The fatigue strength under constant amplitude was evaluated and the mean of the fatigue limit at R = -2.27 derived from the staircase method was 311.2MPa. And the failure probability( F$\sub$p/ ) derived from the strength-stress interference model is 0.0003% at the 99.99% confidence level and the mean factor of safety was 4.2.

• Asia pacific journal of information systems
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• v.11 no.3
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• pp.105-126
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• 2001

The objective of research is to find out exogenous variables that influence the usage and performance EDI in the Korea firms. Specifically the goals of this research are; (1) to examine relationships between exogenous variables, such as management, technology, inter-firm relationship characteristics, and EDI performance, and (2) to measure EDI volume, EDI diversity, EDI depth among Korea firms. The questionnaire consists of two versions; One for the EDI system managers and the other for the EDI users. The analysis of this study is designed as cross level to examine the causal relationship among variables in different analysis level. The reliability and validity of data was tested by explanatory factor analysis, Cronbach's alpha coefficient, confirmatory factor analysis, and correlation analysis. Also, the structural equation model(SEM) analysis was performed to test the usefulness of the model. The analysis results revealed that education level, IS growth, trust, support, power are major influential variables on the usage level and performance of EDI. Especially, persuasive power turned out to be more important than coercive power, and technical financial support from organizations was also found to be a significant variables.

• Journal of the Korea Safety Management & Science
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• v.9 no.6
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• pp.31-38
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• 2007

The construction industry by its nature retains higher level of danger where the smallest of error may lead to a major catastrophe endangering many workers and public safety as well as provoke social criticism. With the aid of quantitative statistical data on safety-related calamity analyzed till this day, this paper handled in depth the analysis of diseases other than the accidents, and selected new variable indexes that influence the indirect sections of calamity that are mostly concealed and incorporated them in a new model. For the factor selection of new calamity evaluation model, FRAT(Frequency, Recency, Amount, Type of merchandise/service)technique of customer-related management in marketing was applied, and as for the significance of each factor in the weight selection of variables. Consequently, considering the graveness of the FRAT itself through safety management experts, the related researches must be expanded.