• Journal of the Economic Geographical Society of Korea
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• v.15 no.3
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• pp.343-357
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• 2012

The Seoul metropolitan subway system can be represented by a graph which consists of nodes and edges. In this paper, we study classification of subway stations and trip behaviour of subway passengers through partitioning the graph of the subway system into roughly equal groups. A weight of each edge of the graph is set to the number of passengers who pass the edge, where the number of passengers is extracted from the transportation card transaction database. Since the graph partitioning problem is NP-complete, we propose a heuristic algorithm to partition the subway graph. The heuristic algorithm uses one of two alternative objective functions, one of which is to minimize the sum of weights of edges connecting nodes in different groups and the other is to maximize the ratio of passengers who get on the subway train at one subway station and get off at another subway station in the same group to the total subway passengers. In the experimental results, we illustrate the subway stations and edges in each group by color on a map and analyze the trip behaviour of subway passengers by the group origin-destination matrix.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.10
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• pp.4678-4702
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• 2018

Traffic Matrix estimation has always caught attention from researchers for better network management and future planning. With the advent of high traffic loads due to Cloud Computing platforms and Software Defined Networking based tunable routing and traffic management algorithms on the Internet, it is more necessary as ever to be able to predict current and future traffic volumes on the network. For large networks such origin-destination traffic prediction problem takes the form of a large under- constrained and under-determined system of equations with a dynamic measurement matrix. Previously, the researchers had relied on the assumption that the measurement (routing) matrix is stationary due to which the schemes are not suitable for modern software defined networks. In this work, we present our Compressed Sensing with Dynamic Model Estimation (CS-DME) architecture suitable for modern software defined networks. Our main contributions are: (1) we formulate an approach in which measurement matrix in the compressed sensing scheme can be accurately and dynamically estimated through a reformulation of the problem based on traffic demands. (2) We show that the problem formulation using a dynamic measurement matrix based on instantaneous traffic demands may be used instead of a stationary binary routing matrix which is more suitable to modern Software Defined Networks that are constantly evolving in terms of routing by inspection of its Eigen Spectrum using two real world datasets. (3) We also show that linking this compressed measurement matrix dynamically with the measured parameters can lead to acceptable estimation of Origin Destination (OD) Traffic flows with marginally poor results with other state-of-art schemes relying on fixed measurement matrices. (4) Furthermore, using this compressed reformulated problem, a new strategy for selection of vantage points for most efficient traffic matrix estimation is also presented through a secondary compression technique based on subset of link measurements. Experimental evaluation of proposed technique using real world datasets Abilene and GEANT shows that the technique is practical to be used in modern software defined networks. Further, the performance of the scheme is compared with recent state of the art techniques proposed in research literature.

• Journal of Korean Society of Transportation
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• v.26 no.6
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• pp.103-112
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• 2008

Implementing hub networks in logistics is generally attractive and effective because of cost savings derived from economies of scale on network transportation, and objective of the hub network design problem is to decide optimal hub locations, and the transportation route of each origin-destination pair. This problem is generally a NP-complete problem not to solve easily, and it is almost impossible to find optimal solutions considering the big-sized network within a reasonable time. This research tried to find optimal logistics strategy in the given big-sized real network and the freight origin-destination data. The objective function, which was proposed by Honor and O'kelly (2001), that rewards economies of scale on network links with increase of transportation volumes, is applied. This thesis proposed the optimal hub network of korea within a reasonable time based on engineering approaches. And it is expected that this thesis can contribute to plan freight policies which can improve to have competitive power in the level of a company or nation by reducing logistic costs.

• Journal of the Korean association of regional geographers
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• v.16 no.4
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• pp.369-386
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• 2010

Migration usually derived from the gap of spatial efficiency and the attractiveness difference between the origin and the destination puts forth significant impact on the regional dynamics of population. Both migration and regional planning or policy are structurally interconnected, exerting impact each other within the circular loops. In order to observe migration characters in the regional dimension, this research depends on social network analysis(SNA) methods which easily portray interrelationship and its weight between the origin and the destination. In specific, it focuses on the application of centrality indicators in order to understand the in- and out-migration patterns and visualize them with spring graphs, pinpointing the in- and out-migration administrative units. This research deals with three migration patterns in 2001 and 2008, respectively: i) in- and out-migration between the nation and Chungbuk Province; ii) in- and out-migration within Chungcheong Areas; and iii) in- and out-migration within Chungbuk Province. Judging from Chungbuk examples, the highest in-migration was recorded at Heungduck District in terms of in- and out-migration between the nation and Chungbuk Province. Seoul and Gyeonggi were two major origins towards Chungbuk Province. Within Chungcheong Areas, Daejeon produced the highest in-migration in 2001. However, Chungnam took that position in 2008.

• Journal of Korean Society of Transportation
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• v.22 no.6
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• pp.89-99
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• 2004

The purpose of this study is to evaluate the value of information on Bus-Route concerning on the User's Individual value. The value of information is estimated with the price of time saving by using the information. The price of unit time for each user is applied to convert the saving time to the cost. To estimate the user's expense from origin to destination the previous model is modified. Bus-travel cost is estimated with variables such as bus-travel time, bus-interval, bus-fare, and the price of walking distance. In this study, to estimate in-vehicle time the bus-travel time model is developed based on the spatial characteristics distinguished by three types of circular-road in the network of Daegu Metropolitan area. For the case study, a set of the origin and destination is selected as Dalsu-gu District Office and East Daegu Train Station respectively. There are several bus-routes which can be used as direct or transferable bus-routes selected. The study showed that when the value of time for individual users is \1,738/hr, there is no benefit to using information of transferable bus-routes. It also showed that the more discount rates of bus fare is increased, the benefit to using information of transferable bus-routes is increased, and that the lower value of time is, the benefit to using information of transferable bus-routes is increased.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.135-142
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• 2010

Wireless mesh network, which is an access network technology, adopts ubiquitous features of ad-hoc network that includes capabilities of self-configuration and self-management. This paper proposes a scheme which enables nodes along route in wireless mesh network to authenticate data and verify data integrity. The scheme distinguishes infra-node, which is a network device used to form mesh network, and user node in ad-hoc network, which operates functions as a sender, receiver or relayer, to deploy different authentication scheme. That is, hop-based authentication scheme along route forming wireless backbone differs from authentication scheme for user nodes in route over MANET. The proposed scheme is less complex than previously proposed schemes from the repects of security setup procedures and managements. In addition, the scheme is able to reduce transmission delay from a source to a destination owing to fast authentication over wireless backbone.

• Journal of the Korean Geographical Society
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• v.52 no.1
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• pp.105-122
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• 2017

The purpose of this study is to understand the urbanization process and identify the Origin-Destination(O-D) of migration in the period of the Japanese occupation, based on the census data about Bu and Jijung-myeon. For this, the study analysed the types and the location of the immigrants' origin(birthplace) whose headed for an urban area. In 1930, as the destinations in the inter-regional migration, the urban areas could be divided into three categories according to the distance: long-, medium- and short-distance. The new urban areas which developed for effective colonial rule by Japanese pulled the long distance immigrant across the Korean Peninsula, and the Chosun Dynasty's traditional cities had the inflow of population from the near and hinterland. All in all, it is proposed that the dual settlement systems of colonial and traditional structures, is the key to understand the Korean urbanization processes basedd on the inter-regional migration during Japanese colonial period.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.3778-3786
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• 2015

This paper aimed to explore the possible popular song's linkage to tourism promotion material. Especially focusing on the lyrics of Korean popular song, which explicitly containing exoticism in title or lyrics in early and mid of 20 centuries, this research verified how authors represented the one of Dann's language of tourism thesis: strangeness perspective in tourism and language of differentiation. Result suggested that song writers, as of their imaginary by-product or personal experience, present exoticism in lyrics of song in various ways: exaggerating, creating, stereo-typing exotic place. Fulfilling the Dann's idea, songs elaborately delivered familiar words, conspicuously by personifying place, allocating young ladies and mentioning origin or hometown. The research was efforts to find the origin of entertainment contents savvy-tourism promotion and also traced potential tourist's collective imagination toward potential overseas tourism destination.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.3
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• pp.243-249
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• 2020

With the development of the 4th Industry Revolution and the progress of related technologies, people have been using various services in a more convenient way in their daily lives. Among these technologies, the smart mobility is a service that effectively transports people or packets from the origin to the final destination using a variety of methods/vehicles. With respect to the smart mobility technology, the shuttle service is operational at the final destination. The conventional shuttle operation only takes into account the shuttle operability and does not consider the shuttle-passenger efficiency at all by the one-way routing. Therefore, in this paper, we propose the smart shuttle algorithm that can change the routes to efficiently support boarding passengers. Our proposed scheme consists of 3 algorithms: the shuttle operating algorithm, the re-routable shuttle traveling algorithm, and the passenger-riding algorithm. All those 3 algorithms are effectively co-operated and collaborated for better performance. In-depth experiments were conducted to analyze and to show the superior performance, resulting in an average 23.6% reduction of destination-arrival time per passenger, average 10.37% reduction of shuttle-waiting time per passenger, and average 15.38% decrease of shuttle traveling time per hour. This proves that our smart shuttle traveling scheme reveals the whole remarkable performance, effectively using the re-routable characteristics.

• 시스템엔지니어링워크숍
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• s.4
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• pp.70-80
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• 2004

Most rail system related simulations currently used are designed to simulate only one discipline system. This obviously assunes the other discipline system are running regularly not being affected by the system being simulated. In this paper a multi discipline simulator is proposed and its design concept is presented.A multi discipline simulator is the simultor in which major subsystems with different technical discipline are simulated simultaneously. The advantage of the simulator is in that it makes it possible to analyze the systems behavior while other discipline system vary. With this we can identify the possible to analyze the systems ehavior find their solutions. A proto type simulator has bee developed using object oriented programming. Object concept was judged best suitable to model the various multi-discipline self-controlling railway subsystems. It was applied to the target system, which is under development by the Korea Railroad Research institute. The test results show it is very useful in design verification. It could also be a good tool in research and development work to make to improe the system.