• Corrosion Science and Technology
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• v.23 no.2
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• pp.93-103
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• 2024

In the present work, a phase-field model for dendritic solidification is applied to hot-dip ZnAlMg coatings to elucidate the morphology of zinc dendrites and the solute segregation leading to the formation of eutectics. These aspects define the microstructure that conditions the corrosion resistance and the mechanical behaviour of the coating. Along with modelling phase transformation and solute diffusion, the implemented model is partially coupled with the tracking of crystal orientation in solid grains, thus allowing the effects of surface tension anisotropy to be considered in multi-dendrite simulations. For this purpose, the composition of a hot-dip ZnAlMg coating is assimilated to a dilute pseudo-binary system. 1D and 2D simulations of isothermal solidification are performed in a finite element solver by introducing nuclei as initial conditions. The results are qualitatively consistent with existing analytical solutions for growth velocity and concentration profiles, but the spatial domain of the simulations is limited by the required mesh refinement.

• ETRI Journal
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• v.46 no.2
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• pp.165-174
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• 2024

We propose a method to suppress the speckle noise and blur effects of the light field extracted from a hologram using a deep-learning technique. The light field can be extracted by bandpass filtering in the hologram's frequency domain. The extracted light field has reduced spatial resolution owing to the limited passband size of the bandpass filter and the blurring that occurs when the object is far from the hologram plane and also contains speckle noise caused by the random phase distribution of the three-dimensional object surface. These limitations degrade the reconstruction quality of the hologram resynthesized using the extracted light field. In the proposed method, a deep-learning model based on a generative adversarial network is designed to suppress speckle noise and blurring, resulting in improved quality of the light field extracted from the hologram. The model is trained using pairs of original two-dimensional images and their corresponding light-field data extracted from the complex field generated by the images. Validation of the proposed method is performed using light-field data extracted from holograms of objects with single and multiple depths and mesh-based computer-generated holograms.

• Proceedings of the Korea Society of Design Studies Conference
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• 2004.05a
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• pp.44-45
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• 2004

With the development of informational machinery and tools in the modern industrial society, the image is expressed diversely as tools of informational transmission and artistic communication. This image is revival equipment and transmissional media in which sound and light are comprehensively formed. The image's intuitive and sensational expressivity can revive subjects and express a fiction, a reality, a nonfiction, and a virtual reality as a communication tool that has synchronicity and the medium of meaning. Because of this, the domain of the image will be gradually extended in the future, and the world of cognizance that can be detected across our living space will absorb the image diversely and react. In this context, the investigator examined what influence image media and equipments have in space as spatial equipments, based on the recognition of cerrelation among the image, space, and mankind, namely, the environmental meaning the mage and the space contain. Therefore, this study was conducted from the aspects of relationship establishment between image equipments that are ever expansive to a variety of domains and the space that accommodates the equipments. As study findings, the influences the image equipments have on space and their expressional features are presented in three aspects: 'the expressional medium of mutual synergy','metaphysical ultra-epithelial space constituent',' and 'object'. This study seems to be meaningful in that we can expect the spatial approach method by purposes and spatial layout of image structures, with this study, through analyzing the meaning of relationship between image equipments and space.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.4
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• pp.234-246
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• 2007

The role of macropore in the hydrological processes is important at the hillslope scale. Developments and distribution of macropores have not been investigated in conjunction with the characteristics of the hillslope such as topography, soil property, and soil moisture. In this study, macropore properties, such as macropore flow and saturation hydraulic conductivity were measured at a hillslope located in Gwangneung Research Forest, Pochun-gun, Gyeonggi-do, South Korea. An intensive field survey provided a refined Digital Elevation Model (DEM) for surface and subsurface topography. Spatial distributions of upslope area and topographic index were obtained through the digital terrain analysis. The total number of monitoring points was 22, and the selected points were distributed along the transect of the digital contour map. Vertical fluxes through macropores were measured using a tension infiltrometer at the depth of 0.1 m from the surface. Spatial and temporal distributions of soil moisture were obtained using an on-line measurement system, TRASE, installed in the study area. Soil moisture for the aforementioned points was measured at 0.1 and 0.3m depths below the surface. The results from tension infiltrometer experiments present that the macropore flows ranged between 21 and 94%, and the measured macroporosities varied from 1.4 to 47%. Macropore flows and macroporosities tended to increase as the measurement location moved to downslope. The ability for water conduction through macropores becomes increasingly developed as the location approaches the outlet of the hillslope.

• Journal of the Korean Society of Radiology
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• v.15 no.6
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• pp.803-811
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• 2021

In this study, the exposure amount of IASCC test worker was evaluated by applying the process simulation technology. Using DELMIA Version 5, a commercial process simulation code, IASCC test facility, hot cells, and workers were prepared, and IASCC test activities were implemented, and the cumulative exposure of workers passing through the dose-distributed space could be evaluated through user coding. In order to simulate behavior of workers, human manikins with a degree of freedom of 200 or more imitating the human musculoskeletal system were applied. In order to calculate the worker's exposure, the coordinates, start time, and retention period for each posture were extracted by accessing the sub-information of the human manikin task, and the cumulative exposure was calculated by multiplying the spatial dose value by the posture retention time. The spatial dose for the exposure evaluation was calculated using MCNP6 Version 1.0, and the calculated spatial dose was embedded into the process simulation domain. As a result of comparing and analyzing the results of exposure evaluation by process simulation and typical exposure evaluation, the annual exposure to daily test work in the regular entrance was predicted at similar levels, 0.388 mSv/year and 1.334 mSv/year, respectively. Exposure assessment was also performed on special tasks performed in areas with high spatial doses, and tasks with high exposure could be easily identified, and work improvement plans could be derived intuitively through human manikin posture and spatial dose visualization of the tasks.

• Journal of Korea Water Resources Association
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• v.52 no.5
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• pp.361-372
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• 2019

The purpose of this study is to develop a two-dimensional land surface flood analysis model based on uniform square grid using the governing equations except for the convective acceleration term in the momentum equation. Finite volume method and implicit method were applied to spatial and temporal discretization. In order to reduce the execution time of the model, parallel computation techniques using CPU were applied. To verify the developed model, the model was compared with the analytical solution and the behavior of the model was evaluated through numerical experiments in the virtual domain. In addition, inundation analyzes were performed at different spatial resolutions for the domestic Janghowon area and the Sebou river area in Morocco, and the results were compared with the analysis results using the CAESER-LISFLOOD (CLF) model. In model verification, simulation results were well matched with the analytical solution, and the flow analyses in the virtual domain were also evaluated to be reasonable. The results of inundation simulations in the Janghowon and the Sebou river area by this study and CLF model were similar with each other and for Janghowon area, the simulation result was also similar to the flooding area of flood hazard map. The different parts in the simulation results of this study and the CLF model were compared and evaluated for each case. The results of this study suggest that the model proposed in this study can simulate the flooding well in the floodplain. However, in case of flood analysis using the model presented in this study, the characteristics and limitations of the model by domain composition method, governing equation and numerical method should be fully considered.

• Journal of radiological science and technology
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• v.31 no.1
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• pp.71-81
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• 2008

Our objective was to evaluate the image of spatial domain filtering as an alternative to additional image reconstruction using different kernels in MDCT. Derived from thin collimated source images were generated using water phantom and abdomen B10(very smooth), B20(smooth), B30(medium smooth), B40 (medium), B50(medium sharp), B60(sharp), B70(very sharp) and B80(ultra sharp) kernels. MTF and spatial resolution measured with various convolution kernels. Quantitative CT attenuation coefficient and noise measurements provided comparable HU(Hounsfield) units in this respect. CT attenuation coefficient(mean HU) values in the water were values in the water were $1.1{\sim}1.8\;HU$, air($-998{\sim}-1000\;HU$) and noise in the water($5.4{\sim}44.8\;HU$), air($3.6{\sim}31.4\;HU$). In the abdominal fat a CT attenuation coefficient($-2.2{\sim}0.8\;HU$) and noise($10.1{\sim}82.4\;HU$) was measured. In the abdominal was CT attenuation coefficient($53.3{\sim}54.3\;HU$) and noise($10.4{\sim}70.7\;HU$) in the muscle and in the liver parenchyma of CT attenuation coefficient($60.4{\sim}62.2\;HU$) and noise ($7.6{\sim}63.8\;HU$) in the liver parenchyma. Image reconstructed with a convolution kernel led to an increase in noise, whereas the results for CT attenuation coefficient were comparable. Image scanned with a high convolution kernel(B80) led to an increase in noise, whereas the results for CT attenuation coefficient were comparable. Image medications of image sharpness and noise eliminate the need for reconstruction using different kernels in the future. Adjusting CT various kernels, which should be adjusted to take into account the kernels of the CT undergoing the examination, may control CT images increase the diagnostic accuracy.

• Korean Journal of Cognitive Science
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• v.27 no.2
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• pp.159-219
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• 2016

Mathematical ability is important for academic achievement and technological renovations in the STEM disciplines. This study concentrated on the relationship between neural basis of mathematical cognition and its mechanisms. These cognitive functions include domain specific abilities such as numerical skills and visuospatial abilities, as well as domain general abilities which include language, long term memory, and working memory capacity. Individuals can perform higher cognitive functions such as abstract thinking and reasoning based on these basic cognitive functions. The next topic covered in this study is about individual differences in mathematical abilities. Neural efficiency theory was incorporated in this study to view mathematical talent. According to the theory, a person with mathematical talent uses his or her brain more efficiently than the effortful endeavour of the average human being. Mathematically gifted students show different brain activities when compared to average students. Interhemispheric and intrahemispheric connectivities are enhanced in those students, particularly in the right brain along fronto-parietal longitudinal fasciculus. The third topic deals with growth and development in mathematical capacity. As individuals mature, practice mathematical skills, and gain knowledge, such changes are reflected in cortical activation, which include changes in the activation level, redistribution, and reorganization in the supporting cortex. Among these, reorganization can be related to neural plasticity. Neural plasticity was observed in professional mathematicians and children with mathematical learning disabilities. Last topic is about mathematical creativity viewed from Neural Darwinism. When the brain is faced with a novel problem, it needs to collect all of the necessary concepts(knowledge) from long term memory, make multitudes of connections, and test which ones have the highest probability in helping solve the unusual problem. Having followed the above brain modifying steps, once the brain finally finds the correct response to the novel problem, the final response comes as a form of inspiration. For a novice, the first step of acquisition of knowledge structure is the most important. However, as expertise increases, the latter two stages of making connections and selection become more important.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8C
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• pp.1113-1124
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• 2004

In this paper, we proposed a hardware(H/W) structure which can compress and recontruct the input image in real time operation and implemented it into a FPGA platform using VHDL(VHSIC Hardware Description Language). All the image processing element to process both compression and reconstruction in a FPGA were considered each of them was mapped into H/W with the efficient structure for FPGA. We used the DWT(discrete wavelet transform) which transforms the data from spatial domain to the frequency domain, because use considered the motion JPEG2000 as the application. The implemented H/W is separated to both the data path part and the control part. The data path part consisted of the image processing blocks and the data processing blocks. The image processing blocks consisted of the DWT Kernel fur the filtering by DWT, Quantizer/Huffman Encoder, Inverse Adder/Buffer for adding the low frequency coefficient to the high frequency one in the inverse DWT operation, and Huffman Decoder. Also there existed the interface blocks for communicating with the external application environments and the timing blocks for buffering between the internal blocks The global operations of the designed H/W are the image compression and the reconstruction, and it is operated by the unit of a field synchronized with the A/D converter. The implemented H/W used the 69%(16980) LAB(Logic Array Block) and 9%(28352) ESB(Embedded System Block) in the APEX20KC EP20K600CB652-7 FPGA chip of ALTERA, and stably operated in the 70MHz clock frequency. So we verified the real time operation of 60 fields/sec(30 frames/sec).

• Journal of Elementary Mathematics Education in Korea
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• v.19 no.3
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• pp.289-304
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• 2015

In this study, connections between the NURI curriculum for 5 years old children and the contents of teacher's manual books according to it and the contents of elementary 1st grade mathematics curriculum and textbooks was analyzed to find the implications that can help to link the two curricula in the development of kindergarten and elementary school mathematics curriculum. The five following implications could be obtained from the analysis. First, it is necessary to connect the contents of the NURI curriculum for 5 years old children which were completed in that curriculum like 'spatial relation'in geometric figure domain and 'data collection'in probability and statistics domain to the contents of the 1st grade curriculum. Second, in the case of the contents not connected between the NURI curriculum for 5 years old children and the contents of elementary 1st grade mathematics curriculum but connected between the NURI curriculum for 5 years old children and the contents of elementary 2nd ~6th grade mathematics curriculum, it is necessary to re-adjust the hierarchy based on one of the curricula. Third, it is necessary to check whether $\ll$K-teacher's manual book$\gg$ obey the NURI curriculum for 5 years old children or not. Fourth, it is necessary to review the related elements of the NURI curriculum for 5 years old children and elementary 2nd ~6th grade mathematics curriculum in [activity] in $\ll$K-teacher's manual book$\gg$. Fifth, it is necessary to handle the mathematics contents explicitly and systematically in [activity] in $\ll$K-teacher's manual book$\gg$.