• Genomics & Informatics
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• v.18 no.4
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• pp.39.1-39.8
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• 2020

Alzheimer's disease (AD) is a chronic, progressive brain disorder that slowly destroys affected individuals' memory and reasoning faculties, and consequently, their ability to perform the simplest tasks. This study investigated the hub genes of AD. Proteins interact with other proteins and non-protein molecules, and these interactions play an important role in understanding protein function. Computational methods are useful for understanding biological problems, in particular, network analyses of protein-protein interactions. Through a protein network analysis, we identified the following top 10 hub genes associated with AD: PTGER3, C3AR1, NPY, ADCY2, CXCL12, CCR5, MTNR1A, CNR2, GRM2, and CXCL8. Through gene enrichment, it was identified that most gene functions could be classified as integral to the plasma membrane, G-protein coupled receptor activity, and cell communication under gene ontology, as well as involvement in signal transduction pathways. Based on the convergent functional genomics ranking, the prioritized genes were NPY, CXCL12, CCR5, and CNR2.

• Journal of Korean Society of Transportation
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• v.20 no.6
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• pp.157-158
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• 2002

• Journal of the Korean Operations Research and Management Science Society
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• v.25 no.1
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• pp.67-84
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• 2000

In this paper, we address a network design problem including the decision of hub facility locatiions which is typically found in a communicatio and a transportation network design studies. Due to the administrative and the geographical restrictions, it is common to assume that each user should be assigned to only one hub facility. To construct such a network, three types of network costs should be considered: the fixed costs of establishing the hubs and the arcs in the network, and the variable costs associated with transversing the network. The complex problem is formulated as a mixed IP embedding a multicommodity flow problem. Exploiting its special structure, a dual-based heuristic is then developed, which yields near-optimal design plans. The test results indicate that the heuristic is an effective way to solve this computationally complex problem.

• Journal of Korean Society of Transportation
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• v.22 no.3 s.74
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• pp.167-177
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• 2004

The Hub-and-spoke strategy is widely used in the field of transportation. According to containerization and the development of transshipment technology, it is also introduced into European rail freight transportation. The objective of this article is to develop a service network design model for rail freight transportation based on the Hub-and-spoke strategy and efficient algorithms that can be applied to large-scale network. Although this model is for strategic decision, it includes not only general operational cost but also time-delay cost. The non-linearity of objective function due to time-delay factor is transformed into linearity by establishing train service variables by frequency. To solve large scale problem, this model used a heuristic method based on decomposition and three newly-developed algorithms. The new algorithms were examined with respect to four test problems base on the actual network of European rail freight and discussed the accuracy of solutions and the efficiency of proposed algorithms.

• Journal of Korea Port Economic Association
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• v.20 no.2
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• pp.187-216
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• 2004

Northeast Asia logistics hub strategy was undertaken by Korean Government to gain a national competitive advantage in Northeast Asia. Current Government has Northeast Asian Economic Hub Strategy including construction of SOC in Northeast Asia for promoting peace, promotion of formation of Northeast Asia Community, logistics hub, Financial hub and national innovation for R&D Cluster. To realize Northeast Asian logistics hub, the Northeast Asia logistics hub road map has undertaken as follows: expansion of logistics infra in Incheon Airport, Busan Port and Gwangyang Port, systematic improvements such as adjustment of investment distribution, special logistics companies, transparent customs in logistics transactions, logistics manpower, improvement of system supporting global logistics and attraction of international logistics companies to the logistics center, construction of seamless and paperless logistics information network, Northeast Asia railway infra. The purpose of this paper is to study investment priority and improvements in the Northeast Asia Logistics Hub Road Map and to contribute to gain the national competitive advantage as logistics hub in Northeast Asia

• Journal of Advanced Navigation Technology
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• v.2 no.2
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• pp.143-156
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• 1998

Incheon International Airport(IIA) is planned to open in about two years. Korean government has an ambition to make IIA a major hub airport in Northeast Asia. The most essential and required condition for an airport to be a successful hub airport in a certain region is to have more efficient flight service network than the other airports in the same region. IIA should compete with Japanese airports to be a major hub in Northeast Asia because Japanese government also has a plan to expand greatly the airport capacity in Tokyo area and Kansai airport in Osaka. It is necessary for both IIA and Korean national air carriers to compose efficient flight service network considering hub competition with Japanese major airports. As the liberalization of international air transport industry would give more marketing freedom to airlines, they would plan the flight service network and flight schedule based on market analysis instead of governmental regulations. In the economically liberalized environment, it is very required to analyze air passengers' flight choice behaviour in order to induce other carriers and passengers through IIA's attractive flight service network. Disaggregate model is more appropriate than aggregate model to analyze consumers' behaviour. The information derived from disaggregate choice model of air passengers could be utilized in devising efficient flight network and schedule plan. Value of travel time or trade off ratio between flight frequency and travel time which could be estimated from discrete choice model could be utilized for scheduling an efficient flight plan for airlines and composing efficient flight service network for IIA.

• Journal of Navigation and Port Research
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• v.44 no.2
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• pp.73-78
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• 2020

The cruise industry in the Mediterranean region increased from 2000-2018, being the second most important region after the Caribbean. The purpose of this study was to analyze the networks and hub ports of the Mediterranean. This paper used the SNA (Social Network Analysis) methodology, which includes Hub and Authority Combined Centrality (HACC) that has been used to analyze cruise port centrality, as well as degree centrality such as In-Degree, Out-Degree, and Betweenness. This empirical study suggests that the top three ports of the Mediterranean ports' network in terms of hub index are Barcelona, Civitavecchia, and Palma de Mallorca. The academic implications are the suggestion for data integration based on real itineraries and numbers of POC (Port of Calls), as well as the selection of the hubs of the targeted areas. The practical implications are suggested such as a clear requirement for cruise industry, as a way to widen the scope for the Mediterranean region and a valuable reference for cruise ship companies to select the best fit home ports.

• The Journal of the Korea Contents Association
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• v.12 no.9
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• pp.348-356
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• 2012

This study is identifying early takeoff phenomenon in relational network like SNS and investigates influence of innovator or hub at early takeoff and diffusion size at takeoff point. The major finding of this study are as follows. First, multinominal-logit analysis conducted to explore the impact of innovator and hub at early stage of information diffusion and early takeoff. Hub in early stage of information diffusion impact early takeoff. Second, our study shows that innovator and hub at early stage of information diffusion impact diffusion size at takeoff point. Third, hub is more impact early takeoff and diffusion size at takeoff point then innovator. This study provides implication for professionals by confirming hub's influence in study of successful information diffusion by early takeoff. The limitation and future direction are discussed.

• Journal of Korea Planning Association
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• v.53 no.7
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• pp.5-22
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• 2018

While the competitiveness of small and medium sized cities has become important for balanced development at the national scale, they have experienced continuous decline in population and employment, particularly those in non-capital regions. In addition, some of small and medium sized cities have been classified into shrinking cities that have declined due to their long-term structural reasons. To address these issues, a regional approach, by which a hub city and its surrounding small and medium sized cities can collaborate has been suggested. Given this background, the purpose of this study is to identify and delineate hub cities and their impact areas by using travel data as a functional network index. This study uses a centrality index to identify the hub cities of small and medium sized cities and Markov-chain model and cluster analysis to delineate regional boundaries. The mean first passage time (MFPT) generated from the Markov-chain model can be interpreted as functional distance of each region. The study suggests a methodological approach delineating the boundaries of regions incorporating functional relationships of hub cities and their impact areas, and provides 59 hub cities and their impact areas. The results also provide policy implications for regional spatial planning that addresses appropriate planning boundaries of regions for enhancing the economic competitiveness of small and medium sized cities and ensuring services for shrinking cities.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6D
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• pp.917-926
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• 2006

Transportation Economies of scale are the essential properties of hub networks. One critical property of the hub network design problem is to quantify cost savings which stem from economies of scale, the costs of operating hub facilities and opportunity costs associated with delays stemming from consolidation of traffic flows. Due to the NP-complete property of the hub location problem, however, most previous researchers have focused on the development of heuristic algorithms for approximate solutions. The purpose of this paper is to develop a hub network design model considering transportation economies of scale from the consolidation of traffic flows. The model is designed to consider the uniqueness of hub networks and to determine several cost components. The heuristic algorithms for the developed model are suggested and the results of the model are compared with recently published studies using real data. Results of the analysis show that the proposed model reflects transportation economies of scale due to consolidation of flows. This study can form not only the theoretical basis of an effective and rational hub network design but contribute to the assessment of existing and planned logistics systems.