• Journal of the Korean Society for Railway
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• 제16권6호
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• pp.503-509
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• 2013

Since the opening of KTX, the number of people coming to KTX stations to use KTX has steadily increased. Passengers have a variety of access modes between a KTX station and their origin/destination. But there is no way to confirm the level of connection strength. So this study examines various connection characteristic variables that can show the connectivity, and examines influencing relationships, and chooses variables that affect connectivity by using a KTX modal split. We will suggest connectivity estimation models between a KTX station and origin/destination based on the selected connected variables.

• The Journal of the Korea Contents Association
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• 제14권9호
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• pp.24-44
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• 2014

This study explores the political meaning of candidate's speech and statement who run for the 18th presidential election in the viewpoint of communication. The visibility of the words and the connectivity between the words are analyzed in the viewpoint of structural aspect and the vision, policy. The visibility of the words is analyzed based on the frequency of the words mentioned in the speech or the statement. The connectivity between the words are analyzed based on the network analysis and expressed by graph. In the case of candidate Park, the key word is the happiness of the people and appointment. The key word for candidate Moon is regime change and the Korean Peninsula and the key word for candidate Ahn is the people and change. This study contributes positively to the study of candidate's discourse in the viewpoint of methodology by using network analysis and exploring scientifically the connectivity of the words. In the theoretical aspect this study uses the results of network analysis for revealing what is the leadership components in the speech and the statement. In conclusion, this study highlights the extension of the communication studies.

• Journal of Korea Port Economic Association
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• 제39권4호
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• pp.269-283
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• 2023

Based on daily data from January 4, 2016 to September 27, 2022, the impact of extreme movements of BDI on shipping companies' network connectivity was analyzed using CoVaR network connectivity. The main results and policy implications are as follows. First, according to the copula model results, the Student-t copula was selected as the most suitable model for COSCO, HMM, HRAG, MAERSK, and WAN. EVER was selected as a time-varying Gumbel copula, and YANG was selected as a time-varying rotated-Gumbel copula. Second, as a result of analysis using the TVP-VAR model, the linkage between shipping companies tended to increase when the BDI turned into an extreme risk state. In the comparison of net connectivity, the roles of COSCO and EVER changed. In addition, in the analysis of net pairwise connectivity, it was found that the change in the extreme risk state of BDI also affected the connectivity of shipping companies. In particular, EVER, WAN, and COSCO showed large changes. Taken together, the extreme fluctuations in BDI changed the role of Asian shipping companies, intensifying competition among shipping companies and strengthening risk delivery. It was confirmed that BDI has a great influence on the network connectivity of shipping companies and has an important influence on the stability of the stock market network. Therefore, the results of this study should consider not only the connectivity of shipping companies according to market conditions, but also the connectivity in extreme situations.

• Journal of Environmental Policy
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• 제13권2호
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• pp.39-63
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• 2014

This article aims to explore the connectivity and centrality between environment law and spatial law, where make implications in environmental planning. To achieve it, we used Network Analysis(NA) as a tool for analyzing the connectivities. 52 environmental Laws and 29 Spatial Laws are selected and used for this analysis. This study also attempts to explain the phenomenon through quantitative study rather than qualitative research. This paper is methodologically the first attempt to Environmental Law study, which will help to understand the structure of complex Environmental Law. The result of the network analysis for connectivity between Spatial Law and Environmental Law demonstrates that two laws are in less mutual relationship with each other. It also supports that Environmental Law and Spatial Law need to be closely connected with each other for effective environmental management.

• Annals of Clinical Neurophysiology
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• 제22권2호
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• pp.82-91
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• 2020

Electroencephalography (EEG) produces time-series data of neural oscillations in the brain, and is one of the most commonly used methods for investigating both normal brain functions and brain disorders. Quantitative EEG analysis enables identification of frequencies and brain activity that are activated or impaired. With studies on the structural and functional networks of the brain, the concept of the brain as a complex network has been fundamental to understand normal brain functions and the pathophysiology of various neurological disorders. Functional connectivity is a measure of neural synchrony in the brain network that refers to the statistical interdependency between neural oscillations over time. In this review, we first discuss the basic methods of EEG analysis, including preprocessing, spectral analysis, and functional-connectivity and graph-theory measures. We then review previous EEG studies of brain network characterization in several neurological disorders, including epilepsy, Alzheimer's disease, dementia with Lewy bodies, and idiopathic rapid eye movement sleep behavior disorder. Identifying the EEG-based network characteristics might improve the understanding of disease processes and aid the development of novel therapeutic approaches for various neurological disorders.

• Journal of Biomedical Engineering Research
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• 제27권4호
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• pp.170-179
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• 2006

The purpose of this study was to investigate the spatiotemporal cortical activation pattern and functional connectivity during visual perception of words. 61 channel recordings of electroencephalogram were obtained from 15 subjects while they were judging the meaning of Korean, English, and Chinese words with concrete meanings. We examined event-related potentials (ERP) and applied independent component analysis (ICA) to find and separate simultaneously activated neural sources. Spectral analysis was also performed to investigate the gamma-band activity (GBA, 30-50 Hz) which is known to reflect feature binding. Five significant ERP components were identified and left hemispheric dominance was observed for most sites. Meaningful differences of amplitudes and latencies among languages were observed. It seemed that familiarity with each language and orthographic characteristics affected the characteristics of ERP components. ICA helped confirm several prominent sources corresponding to some ERP components. The results of spectral and time-frequency analyses showed distinct GBAs at prefrontal, frontal, and temporal sites. The GBAs at prefrontal and temporal sites were significantly correlated with the LPC amplitude and response time. The differences in spatiotemporal patterns of GBA among languages were not prominent compared to the inter-individual differences. The gamma-band coherence revealed short-range connectivity within frontal region and long-range connectivity between frontal, posterior, and temporal sites.

• The Korean Journal of Applied Statistics
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• 제29권6호
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• pp.1129-1145
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• 2016

Functional neuro-connectivity is one of the main issues in brain science in the sense that it is closely related to neurodynamics in the brain. In the paper, we choose fMRI as a main form of response data to brain activity due to its high resolution. We review methods for analyzing functional neuro-connectivity assuming that measurements are made on physiological responses to neuron activation. This means that we deal with a state-space and measurement model, where the state-space model is assumed to represent neurodynamics. Analysis methods and their interpretation should vary subject to what was measured. We included analysis results of real fMRI data by applying a high-dimensional autoregressive model, which indicated that different neurodynamics were required for solving different types of geometric problems.

• Journal of the Korean association of regional geographers
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• 제21권1호
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• pp.39-61
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• 2015

This paper reviews literature on urban connectivity, and reconsiders the concept of polycentric urban region and its analysis methods, and then, applying them, explores the inter-city flight connectivity and polycentricity in the Yeongnam Region. As results of analysis, it has been identified that the entropy index shows a relatively dispersing pattern of the urban network of the region, and that the dominance index reveals a more polycentric (that is, less hierarchic) character of the region than that of the Capital Region, while some differences are found among individual cities in the symmetry of connectivity and the dominance and/or dependence index. Even though flows of products in textile, basic metals, and automobile industries in sub-divisions of manufacture appear a pattern of concentring into the first central city, the urban network of the Yeongnam Region in general can be characterized as a polycentrism, and policy for polycentric regional development would be suggested.

• Journal of Forest and Environmental Science
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• 제40권3호
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• pp.241-249
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• 2024

Human development activities have led to changes in land cover, resulting in the loss of green spaces such as forests and agricultural lands. This loss accompanies issues of habitat reduction and hindrance to wildlife movement. Due to the decrease in urban green spaces, urban green connectivity is reducing. This study aims to analyze changes in green space connectivity through structural and functional changes in green spaces caused by land cover changes. Quantitative analysis of landscape patterns using landscape indices through Fragstats model was employed to analyze the structural changes in green spaces. This study used seven landscape indices to assess the fragmentation and isolation of green spaces. The analysis was focused on changes occurring in agricultural lands, forests, and grasslands within Yongin-si, South Korea, over 20 years from 1989 to 2019. Among the landscape indices for forests, PLAND showed a decrease of approximately 8.2% from 1989 to 2009, while NP exhibited a decline of about 2,025 patches. This indicates both a reduction in the total area of green spaces in Yongin-si. Also, we analyzed functional changes based on landscape index variations in forest land within the study area between 2009 and 2019, and least-cost path (LCP) analysis was conducted using Linkage Mapper. Results yielded 18 and 16 links for 2009 and 2019, respectively, with 12 common links. It was observed that five links showed a slight decrease, indicating partial deletions of links, contributing to the fragmentation and discontinuity of forests.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제35권3호
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• pp.671-678
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• 2015

When evaluating the feasibility of construction projects of large-scaled transportation facilities such as roads or railways based solely on the result of the economic analysis, less development indicators are politically reflected on the investment decision-making because regions whose socio-economic indicators are poor may be disadvantaged or underserved for the projects. Existing less development indicators, however, does not consider the transportation connectivity which indicates how effective the transportation networks are established for the transport of people and goods. In this study, travel time contour maps, travel distance and travel time between regions, and a route curvature were utilized to define new indices which reflect transportation connectivity on the less development indicators. When the new indices are applied, the existing rankings of under-developedness were changed, which means that transportation connectivity could effect on the political decision. In this study, we also suggested the necessity of considering the transportation connectivity when evaluating less development indicators, developed measures of inter-regional linkages, and performed the whole procedures of combining existing and new indices to evaluate the less development indicators.