• Korean Journal of Environment and Ecology
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• v.32 no.4
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• pp.425-439
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• 2018

W investigated the environmental factors and inhabiting biota such as macrophytes and zooplankton in 43 sites located on Jeju Island from May and June 2017 to evaluate the spread and ecosystem risk of dotted duckweed (landoltia punctata) which was recently found for the first time in Jeju Island. Dotted duckweeds were found in a total of 18 sites which tended to show low biomass of aquatic macrophyte species other than the dotted duckweed. We conducted a pattern analysis using SOM (Self-Organizing Map), which extracts information through competitive and adaptive properties, to analyze the effect of inhabiting biota on aquatic macrophytes such as the dotted duckweed and environmental factors. The SOM analysis showed that the inhabiting biota such as the zooplankton affected the biomass of aquatic macrophytes than they did the environmental factors. In particular, the biomass of dotted duckweed was positively related to plant-attached species (Alona, Chydorus, and Pleuroxus). Considering that low density of aquatic macrophytes covers the streams and wetlands on Jeju Island because of irregular water source and sharp change of water depth, the dotted duckweeds are likely to play an essential role as the vital habitat for micro-biota including zooplankton in wetlands and streams on Jeju Island. Furthermore, considering that organic matters are utilized as the primary food source in the areas occupied by dotted duckweed, dotted duckweeds have the role of being both habitat and food source. Although the dense growth of dotted duckweed adversely affects growth and development of some aquatic plants due to the shadow effect, it is due to the dominance of floating plants on the water surface should not be regarded as the risk of the dotted duckweed. In conclusion, the dotted duckweeds have spread and settled in most of the water systems on Jeju Island, their impact on inhabiting biota and the aquatic environment was minor. It is necessary to monitor the distribution and spread of dotted duckweeds in the inland areas outside of Jeju Island in the future.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.3
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• pp.1-12
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• 2001

In this paper, we investigate and analyze weight distribution of feed forward two-layer neural networks with a hidden layer in order to understand and improve time-consuming training process of neural networks. Generally, when a new problem is presented, neural networks have to be trained again without any benefit from the previous training process. In order to address this problem, training process is viewed as finding a solution point in the weight space and the distribution of solution points is analyzed. Then we propose to initialize neural networks using the information of the distribution of the solution points. Experimental results show that the proposed initialization using the weight distribution provides a better performance than the conventional one.

• Journal of Advanced Navigation Technology
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• v.27 no.4
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• pp.457-462
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• 2023

We proposed a flexible link configuration in a system combining mid-span spectral inversion (MSSI) and dispersion management used for long-distance transmission of high-capacity optical signals such as wavelength division multiplexing signals, and examined specific methods to increase chromatic dispersion and nonlinear distortion compensation effects. The dispersion map proposed to increase the flexibility of dispersion-managed link configuration has a 'random-inverse' structure. That is, in the proposed dispersion map, the residual dispersion per span (RDPS) of each fiber span in the first half section up to the optical phase conjugator is randomly distributed, and the RDPS distribution in the second half section reverses the distribution pattern of the first section. Although the proposed dispersion map has a random distribution of RDPS, it was confirmed that the distortion compensation effect is improved due to the fact that the dispersion profile is symmetrical with respect to the optical phase conjugator. In the dispersion map of the 'random-inverse' configuration, it was also confirmed that the compensation effect of the distorted wavelength division multiplexing signal becomes improved when the magnitude of the RDPS allocated to each fiber span is large.

• Journal of Astronomy and Space Sciences
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• v.22 no.3
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• pp.263-272
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• 2005

For the Communication, Ocean and Meteorological Satellite (COMS) which will be launched in 2008, an algorithm for finding the precise location of the sun-glint point on the ocean surface is studied. The precise locations of the sun-glint are estimated by considering azimuth and elevation angles of Sun-satellite-Earth geometric position and the law of reflection. The obtained nonlinear equations are solved by using the Newton-Raphson method. As a result, when COMS is located at $116.2^{\circ}E$ or $128.2^{\circ}E$ longitude, the sun-glint covers region of ${\pm}10^{\circ}(N-S)$ latitude and $80-150^{\circ}(E-W)$ longitude. The diurnal path of the sun-glint in the southern hemisphere is curved towards the North Pole, and the path in the northern hemisphere is forwards the south pole. The algorithm presented in this paper can be applied to predict the precise location of sun-glint region in any other geostationary satellites.

• Journal of the Economic Geographical Society of Korea
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• v.8 no.1
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• pp.17-29
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• 2005

This study has attempted to analyze the spatial structure of industrial agglomerations with elaborated spatial econometric techniques. First of all, spatial patterns and structures of industrial agglomerations in Korea show a multi-polar spatial pattern of industrial agglomeration, Major industries from industrial agglomerations in the Seoul Metropolitan Area, part of the Chungcheong Area and Dongnam Area. Second, as some industrial agglomerations show an agglomerative pattern beyond a regionally based-administrative jurisdiction, the effects of agglomeration seem to be produced across regionally based-administrative jurisdictions. Finally, it can be considered that industrial agglomerations have generally been produced by spatial divisions of labor in which the functions of conception and execution are separated from each other. According to this results, in designing regional innovation systems, their spatial coverage should draw upon an extended region with a few adjacent provinces, and there is a need to form networked clusters in order to sufficiently capitalize upon the spatial spillovers of agglomerations.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.2
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• pp.179-189
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• 2000

This study is tried to organic combination in implementing the suitability analysis of urban landuse between GSIS and ANN(Artificial Neural Network). ANN has merit that can decide rationally connectivity weights among neural network nodes through procedure of learning. It is estimated to be possible that replacing the weight among factors needed in spatial analysis of the connectivity weight on neural network. This study is composed of two kinds of neural networks to be executed. First neural network was used in the suitability analysis of landuse and second one was oriented to analyze of optimum landuse pattern. These neural networks were learned with back-propagation algorithm using the steepest gradient which is embodied by C++ program and used sigmoid function as a active function. Analysis results show landuse suitability map and optimum landuse pattern of study area consisted of residental, commercial. industrial and green zone in present zoning system. Each result map was written by the Grid format of Arc/Info. Also, suitability area presented in the suitability map and optimum landuse pattern show distribution pattern consistent with theroretical concept or urban landuse plan in aspect of location and space structure.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.3
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• pp.77-84
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• 2015

The key objective of this research is to review the effectiveness of spatial regression to identify the influencing factors of spatial distribution patterns of floating population. To this end, global and local spatial autocorrelation test were performed using seoul floating population survey(2014) data. The result of Moran's I and Getis-Ord $Gi^*$ as used in the analysis derived spatial heterogeneity and spatial similarities of floating population patterns in a statistically significant range. Accordingly, Geographically Weighted Regression was applied to identify the relationship between land use attributes and population floating. Urbanization area, green tract of land of micro land cover data were aggregated in to $400m{\times}400m$ grid boundary of Seoul. Additionally public transportation variables such as intersection density transit accessibility, road density and pedestrian passage density were adopted as transit environmental factors. As a result, the GWR model derived more improved results than Ordinary Least Square(OLS) regression model. Furthermore, the spatial variation of applied local effect of independent variables for the floating population distributions.

• Journal of the Society of Disaster Information
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• v.17 no.1
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• pp.120-127
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• 2021

Purpose: In this study, the effect of changes in the variables related to water droplets on the spray density on the floor in the analysis of the water mist fire protection system using FDS was analyzed. Method: When the spray of the water mist nozzle was analyzed in FDS, Particles Per Seconds, Particle Velocity, Size Distribution, and Spray Pattern Shape that can be set in relation to droplets were input to review the analyzed results. Result: In the analysis results, when the number of particles per second was set above a certain value, the spray density of the floor was similar. In the case of Particle Velocity, as the velocity decreases, the spray density of the central portion increases but decreases at a distance of 0.15m or more. From the analysis of the change in the size distribution function, it was found that an increase in the 𝛾 value increases the spray density of the central part, but the value at a remote location decreases. Compared to the result of applying the Gaussian distribution, the median value decreases dramatically when the uniform distribution is applied, but the value at the adjacent position increases. Conclusion: Variables related to the droplet properties of the FDS affect the spray density of the floor. Therefore, in order to increase the reliability of results before performing analyses such as fire suppression or cooling, a sufficient review of input variables is required.

• Journal of the Korean Regional Science Association
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• v.37 no.2
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• pp.63-82
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• 2021

This study aims to explore how manufacturing start-up activities from 2000 to 2018 have changed spatially and to predict changes in distribution patterns of future start-up activities. For the analysis, the Census on Establishments microdata from 2000 to 2018 were used, and the manufacturing industry was classified into four detailed industrial groups according to the 40 manufacturing standards presented by the Korea Institute for Industrial Economics and Trade's ISTANS. According to the results, start-up activities in industries that require high technology levels are concentrated in southern Gyeonggi region, and other start-up activities are concentrated outside of the metropolitan area. When the distribution change from 2018 to 2036, extending the trend from 2000 to 2018, it was confirmed that there was a high possibility of a rise in the hierarchy in the future in regions adjacent to regions where start-up activities occur. This study aimed to provide implications for regional policies related to fostering start-ups and creating jobs by dynamically analyzing the location pattern of manufacturing start-ups, which is a major source of job creation.

• Korean Journal of Food Science and Technology
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• v.32 no.6
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• pp.1291-1297
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• 2000

Particle size distribution, pasting properties by Rapid Visco Analyser, and textural properties of acorn, mungbean and buckwheat starches, which are the basic raw materials for mook, are compared. The major particle size of mungbean starch was $10{\sim}30$ micron, whereas acorn and buckwheat starches were $5{\sim}20$ micron. At the same starch concentration, mungbean starch had the highest peak viscosity, breakdown and setback. Acorn starch showed the lowest peak viscosity and breakdown. The peak viscosity of buckwheat starch was close to that of mungbean, however the trough and final viscosity were comparable to those of acorn starch. At the same peak viscosity, mungbean starch showed the lowest trough and final viscosity and the highest breakdown and setback. Acorn starch was differentiated from buckwheat starch in that the former had the higher value of setback. The textural properties of mungbean starch gel were significantly different from others. The texture of gels from acorn and buckwheat starches revealed that only the hardness and gumminess were different each other. The hardness of starch gels were negatively correlated with trough and final viscosity, and positively correlated with setback.