• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.493-500
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• 2004

The existence and extent of non-thermal phenomena in galaxy clusters is now well established. A key question in our understanding of these phenomena is the origin of the relativistic electrons which may be constrained by the modelling of the fine radio properties of radio halos and of their statistics. In this paper we argue that present data favour a scenario in which the emitting electrons in the intracluster medium (ICM) are reaccelerated in situ on their way out. An overview of turbulent-particle acceleration models is given focussing on recent time-dependent calculations which include a full coupling between particles and MHD waves.

• The Journal of Information Systems
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• v.17 no.2
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• pp.113-135
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• 2008

This study introduces the construct of social influence and combines the construct with the flow theory and TAM framework Subjective norm, image, and visibility identified as the dimensions of social influence are hypothesized to influence flow and perceived usefulness, and then the intention to use of online community. Data were collected through a survey of respondents who have the experience of using an online community, and analyzed by using structure equations modelling. The major findings of this study are as follows: First, subjective norm was found to have a positive influence on flow and intention to use. Second, image was found to have a positive effect chi flow and perceived usefulness. Third, visibility was found to have a positive influence on perceived usefulness. Finally, flow and perceived usefulness were also found to have a positive effect on the intention to use. Implications of these findings are discussed for researchers and practitioners.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.10
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• pp.833-839
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• 2012

In this paper, we analyze the reconstruction error in the modeling of flow field on BFS(Backward Facing Step). In order for the mathematical modelling of a density on the field, the spatial and temporal modes are extracted by POD(Proper Orthogonal Decomposition) method. After formulating the modeling error, we summarize the relationship between the energy strength and the reconstruction errors. Moreover the allowable modeling error limits in the flow control point of view are confined by analysing in the frequency domain as well as time domain of the reconstructed data.

• 대한예방의학회:학술대회논문집
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• 1999.10a
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• pp.181-182
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• 1999

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.299-304
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• 1998

Flood control of the Mekong delta should be developed over time for rural as well as urban areas. The hydraulic modelling effort is aimed an investigating flow distribution and water level. For the flood control study the flood model made with the VRSAP program is used. Concerning future improvement of the models it is recommended to improve the quality of water level and discharge, extend the number of the measuring locations needed for input for the models, systematically review and analyze future measurement campaigns in order to obtain better understanding of the complex hydraulic aspects, verify and update the topographical data used to model the rivers and cannals, carry out detailed calibration and verification of the models on water levels, discharges etc.

• Journal of the Korean Society of Combustion
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• v.7 no.4
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• pp.10-20
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• 2002

This paper discusses effect of solid mass inventory on the hydrodynamic characteristics of circulating fluidized bed(CFB). Operating parameters of solid mass inventory and air flow rates were varied to understand their effects on fludization pattern. Experimental measurements were made in a CFB of which height and diameter are 3m and 0.05m respectively. Black SiC particles ranging from $100{\mu}m\;to\;500{\mu}m$ were employed as the bed material. Superficial gas velocity of riser and J-valve fluidizing velocity were in the ranges of $1.39{\sim}3.24m/s\;and\;0.139{\sim}0.232m/s$, respectively. The axial solid fraction and solid circulation rate of CFB were calculated based on the experimental data and compared with modellings through IEA-CFBC Model and commercial CFD code.

• Journal of Ocean Engineering and Technology
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• v.8 no.1
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• pp.71-83
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• 1994

The axial and torsional coupled vibration of marine propeller shafts can be mainly caused by actual shape of the crank shaft and hydrodynamic forces and moments due to propellers : the former leads to stiffness matrix coupling and the latter leads to inertia and damping matrix coupling. In the present paper the characteristics of the coupled vibration of marine propeller shafts due to hydrodynamic coupling is investigated in details. First, the modelling procedure of the system and analysis technique are also developed. To verify the present method the numerical calculations were also performed. Finally, the results were compared with existing data in the literature and it was found to be in good agreement.

• Journal of Environmental Science International
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• v.7 no.6
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• pp.817-825
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• 1998

A three-dimensional ecosystem model is applied to the Suyoung Bay, located at the southeastern part of Korea, to study of the material distribution in the time scale of several tens days. The model has included of the DIN(Dissolved Inorganic Nitrogen), DIP(Dissolved Inorganic Phosphate), phytoplankton, zooplankton and detritus, and also was coupled with the physical processes. The spatial distribution of chlorophyll-a and primary productivity in the model is determined by the physical and chemical-biological parameters. The horizontal distributions of the DIN, DIP and chlorophyll-a are decreased from the coast to the off-shore, though the nutrients show some more complicated pattern than the chlorophyll-a. The nutrient contents in the off-shore are low, and thus a relatively low productivity(chlorophyll-a) are presented. On the whole, the distribution of the results of model are smoother than the observed ones and some small scale variation in the observed data cannot be reproduced by the model due to the resolution limits of model. However, the basic pattern and the quantitavities has been reproduced by the model well.

• IE interfaces
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• v.18 no.4
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• pp.465-476
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• 2005

Evolutionary operation is a useful tool for improving full-scale manufacturing process by systematically changing the levels of the process variables without jeopardizing the product. This paper presents a system design for the evolutionary operation software called 'evolutionary optimizer'. Evolutionary optimizer consists of four modules: factorial design, many variables, mixture, and mean/dispersion. Context diagram, data flow diagram and entity-relationship modelling are used to systematically design the evolutionary optimizer system.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.417-424
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• 2005

Observed field behaviors are frequently different from the behaviors predicted in the design state due to several uncertainties involved in soil properties, numerical modelling, and error of measuring system even though a sophisticated numerical analysis technique is applied to solve the consolidation behavior of drainage-installed soft deposits. In this study, genetic algorithms are applied to back-analyze the soil properties using the observed behavior of soft clay deposit composed of multi layers that shows complex consolidation characteristics. Utilizing the program, one might be able to appropriately predict the subsequent consolidation behavior from the measured data in an early stage of consolidation of multi layered soft deposits. Example analyses for drainage-installed multi-layered soft deposits are performed to examine the applicability of proposed back-analysis method.