• Journal of Powder Materials
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• v.27 no.6
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• pp.484-489
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• 2020

In this study, acoustic and viscosity data are collected in real time during the ball milling process and analyzed for correlation. After fast Fourier transformation (FFT) of the acoustic data, changes in the signals are observed as a function of the milling time. To analyze this quantitatively, the frequency band is divided into 1 kHz ranges to obtain an integral value. The integrated values in the 2-3 kHz range of the frequency band decrease linearly, confirming that they have a high correlation with changes in viscosity. The experiment is repeated four times to ensure the reproducibility of the data. The results of this study show that it is possible to estimate changes in slurry properties, such as viscosity and particle size, during the ball milling process using an acoustic signal.

• Journal of Korean Society on Water Environment
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• v.26 no.5
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• pp.822-833
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• 2010

Temperature increase due to climate changes causes change of water temperature in rivers which results in change of water quality etc. and the change of river ecosystem has a great impact on human life. Analyzing the impact of current climate changes on air and water temperature is an important thing in adapting to the climate changes. This study examined the effect of climate changes through analyzing air temperature trend for Nakdong river basin and analyzed the elasticity of air-water temperature to understand the effect of climate changes on water temperature. For analysis air temperature trend, collecting air temperature data from the National Weather Service on main points in Nakdong river basin, and resampling them at the units of year, season and month, used as data for air temperature trend analysis. Analyzing for elasticity of air-water temperature, the data were collected by the Water Environment Information system for water temperature, while air temperature data were collected at the National Weather Service point nearest in the water temperature point. And using the results of trend analysis and elasticity analysis, the effect of climate changes on water temperature was examined estimating future water temperature in 20 years and 50 years after. It is judged that analysis on mutual impact between factors such as heat budget, precipitation and evapotranspiration on river water temperature affected by climate changes and river water temperature is necessary.

• Nuclear Engineering and Technology
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• v.52 no.9
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• pp.2072-2077
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• 2020

The purpose of this study was to demonstrate the feasibility of sensing changes in a tumor during boron neutron capture therapy (BNCT) using a Monte Carlo simulation tool. In the simulation, an epi-thermal neutron source and a water phantom including boron uptake regions (BURs) were simulated. Moreover, this simulation also included a detector for positron emission tomography (PET) scanning and an adaptively-designed collimator (ADC) for PET. After the PET scanning of the water phantom, including the 511 keV source in the BUR, the ADC was positioned in the PET's gantry. Single prompt gamma rays were collected through the ADC during neutron irradiation. Then, single prompt gamma ray-based tomography images of different sized tumors were acquired by a four-step process. Both the signal-to-noise ratio (SNR) and tumor size were analyzed from each step image. From this analysis, we identified a decreasing trend of both the SNR and signal intensity as the tumor size decreased, which was confirmed in all images. In conclusion, we confirmed the feasibility of sensing changes in a tumor during BNCT using PET and an ADC through Monte Carlo simulation.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.7-10
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• 1996

The purpose of this experimental investigation is to examine the influence of the catheter on local pressure changes and flow rate in an arterial branch model similar to the femoral artery of man. Effects of branch to main lumen flow rate ratios and the locations of catheter tip were found to be significant on the local pressure changes. Relatively large pressure drops due to obstruction effects may induce endothelial cell damage, which have been reported to be the primary cause of the initiation of the atherosclerosis.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.44
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• pp.69-79
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• 1997

We investigate both of central and dispersion tendencies of the observed test statistics in control charts in order to judge whether a production process is abnormal or not. In order to do it, first, we study about detection of changes of the population mean as a central tendency The $\bar{x}$ and x control charts are used for detecting the change of the population mean $\mu$. We shows the probability detecting the change of population mean using the $\bar{x}$ and x control charts. Secondly, we study about detection of changes of the population standard deviation as a dispersion tendency in the s control chart. In our studies, for the given several parameters the detection probabilities of changes of central and dispersion tendencies are calculated, the necessary sample size values n are suggested for detecting the changes, and their informations are given as various tables.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.40
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• pp.37-52
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• 1996

Nowadays the marketing environment has become an important factor which should be seriously considered by all the managers of modern firms. The survivals of modern firms are basically influenced by the changes of marketing environment. Particularly, it is necessary for firms to pursue the rational and efficient managerial activities since the recent environment is characterized by the stiff competition and rapid changes. First of all, this paper is trying to theoretically examine how the environment of the marketing system has been changing in terms of different periods and macro-levels. Secondly, in order to understand the patterns of consumers' perceptions on the environmental changes, some hypotheses have been established and relevant data have been collected. And, in order to analyse the results of this study, the followings have been implemented : Pilot analyses on the experimental environment and variables, the selection of research methodology, the test hypotheses, and the summary of the results. Finally, some practical implications have been suggested in order to help marketing managers formulate the efficient marketing strategic.

• Journal of the Korean Society for Precision Engineering
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• v.8 no.4
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• pp.64-75
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• 1991

The design of structures of modern industry has developed to satisfy stringent service, realiability and safety. Up to now, geometric profile which means surface foughness and dimension accuracy is mainly treated in manufacturing process of work surface. But it is inevitable to evaluate changes of surface geometry as well as the nature of alterations in surface layers because surface of workpiece changes as a result of phase transformation, chemical changes, plastic deformation and stress changes. This paper is to present principal data for safety design by verifying the effect of grinding conditions and method in grinding layers and to explain the method of measuring surface integrity. In this paper, structural steel(SM20C) is used as a workpiece. Of integrity, surface roughness in view of surface texture is analyzed by frequency domain and residual stress, structures and defect of ground layers in view of surface metallurgy are investigated.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.208-217
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• 2021

3D-CNN is one of the deep learning techniques for learning time series data. However, these three-dimensional learning can generate many parameters, requiring high performance or having a significant impact on learning speed. We will use these 3D-CNNs to learn hand gesture and find the parameters that showed the highest accuracy, and then analyze how the accuracy of 3D-CNN varies through input data changes without any structural changes in 3D-CNN. First, choose the interval of the input data. This adjusts the ratio of the stop interval to the gesture interval. Secondly, the corresponding interframe mean value is obtained by measuring and normalizing the similarity of images through interclass 2D cross correlation analysis. This experiment demonstrates that changes in input data affect learning accuracy without structural changes in 3D-CNN. In this paper, we proposed two methods for changing input data. Experimental results show that input data can affect the accuracy of the model.

• Journal of the Korean Solar Energy Society
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• v.27 no.2
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• pp.95-101
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• 2007

The surface changes due to urban expansion and the increase of artificial heat releases have brought significant climate changes such as heat island phenomenon in urban area. Furthermore, these changes also have brought serious problems such as air temperature increase, wind changes, and air pollution in urban area. Comprehensive analytical technologies considering various effects are required to analyse complicated mechanism of climate changes, and review the efficient measures. In this research, the effect of the urban expansion in Tokyo and Bangkok area on urban environment will be discussed. By using CFD, urban development and the mechanism of global warming and wind change are studied in those two cities. As a result of numerical research, the surface changes of city could bring the environmental changes in urban area.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2003.08a
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• pp.259-269
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• 2003

The necessary of predicting changes in tidal regime that would caused by large coastal engineering developments has been led to increased numerical modeling of tides on the continental shelf since 1970s (Flather, 1976; Choi, 1978; Greenberg, 1979). (omitted)