• Journal of Korean Society of Transportation
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• v.22 no.4 s.75
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• pp.85-96
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• 2004

Given a Path represented by a sequence of link numbers in a transportation network, the reasonable path is defined as a path that any link is appeared multiple times in it. Application of the link labelmethod(LLM) to the shortest path algorithms(SPA) enables to model the reasonable path choice behavior in urban networks. This study aims at expanding the LLM to a Kth shortest path algorithms(KPSA), which adopts the node label setting method. The small-scaled network test demonstrated that the proposed algorithm works correctly and the revised Sioux fall network test showed that the path choice behaviors are reasonably reflected. In the large-scaled network based on the South Korea peninsula, drivers' route diversion perceptions are included as cost terms in total cost. The algorithm may be applied as an alternative route information tools for the deployment of ATIS.

• Journal of the Korean Regional Science Association
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• v.32 no.1
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• pp.67-82
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• 2016

This study aims to test the spatial mismatch hypothesis by exploring the relationship between income and commuting time in Seoul, Korea. For this purpose, we analyze the commuting times of individuals who commute to Seoul, using the data for the metropolitan household survey. We employed a hierarchial linear model(HLM) to capture the effects of both individual attributes and regional attributes, and their interactions. The results show that the commuting time decreases with household income controlling for the regional attributes, and the effect of income increases with the housing price of the location of a commuter's firm. This implies that the spatial mismatch holds for Seoul as follows: Lower personal income and housing affordablility extend individuals' commuting times, and the destinations' characteristics such as housing type and land use also have impacts on commuting time. These results have some policy implications for achieving social equity in terms of spatial structure of the city.

• The Journal of the Korea Contents Association
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• v.16 no.6
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• pp.516-528
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• 2016

Tourism information related to the selection and the images formation of tourist destinations is getting more important in tourism industry, and the problems of information overflow is also on the rise simultaneously. And this information overflow can affect the tourists' cognition, emotion and attitudes about tourism information. The objective of this study is to assess their information overload on tourism information on tourists' emotion, attitude and information searching effort. Data were collected from total 438 people with 224 people at public spaces in Seoul, Korea and 214 people at public spaces in Xi'an, China. This study conducts confirmatory factor analysis, correlation analysis and structural equation modelling to verifying 5 hypothesis related to information overflow. The main results of the study show that the cognition of information overload can lead to positive effect to tourists' positive emotion, attitude and searching effort.

• Journal of the Korea Society of Computer and Information
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• v.19 no.7
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• pp.103-111
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• 2014

This paper proposes a modified algorithm that improves on Dijkstra's algorithm by applying it to purely two-way traffic paths, given that a road where bi-directional traffic is made possible shall be considered as an undirected graph. Dijkstra's algorithm is the most generally utilized form of shortest-path search mechanism in GPS navigation system. However, it requires a large amount of memory for execution for it selects the shortest path by calculating distance between the starting node and every other node in a given directed graph. Dijkstra's algorithm, therefore, may occasionally fail to provide real-time information on the shortest path. To rectify the aforementioned shortcomings of Dijkstra's algorithm, the proposed algorithm creates conditions favorable to the undirected graph. It firstly selects the shortest path from all path vertices except for the starting and destination vertices. It later chooses all vertex-outgoing edges that coincide with the shortest path setting edges so as to simultaneously explore various vertices. When tested on 9 different undirected graphs, the proposed algorithm has not only successfully found the shortest path in all, but did so by reducing the time by 60% and requiring less memory.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2B
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• pp.183-191
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• 2004

Single shortest path routing is known to perform poorly for Internet traffic engineering (TE) where the typical optimization objective is to minimize the maximum link load. Splitting traffic uniformly over equal cost multiple shortest paths in OSPF and IS-IS does not always minimize the maximum link load when multiple paths are not carefully selected for the global traffic demand matrix. However, among all the equal cost multiple shortest paths in the network, a set of TE-aware shortest paths, which reduces the maximum link load significantly, can be found and used by IP routers without any change of existing routing protocols and serious configuration overhead. While calculating TE-aware shortest paths. the destination-based forwarding constraint at a node should be satisfied, because an IP router will forward a packet to the next-hop toward the destination by looking up the destination prefix. In this paper, we present a problem formulation of finding a set of TE-aware shortest paths in ILP, and propose a simple heuristic for the problem. From the simulation results, it is shown that TE-aware shortest path routing performs better than default shortest path routing and ECMP in terms of the maximum link load with the marginal configuration overhead of changing the next-hops.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9B
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• pp.577-588
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• 2007

The rapid growth of the Internet has stimulated the development of various new applications and services, and the service providers and the Internet users now require different levels of service qualities rather than current best-effort service which treats all incoming packet equally. Therefore, next generation routers should provide the various levels of services. In order to provide the quality of services, incoming packets should be classified into flows according to pre-defined rules, and this should be performed for all incoming packets in wire-speed. Packet classification not only involves multi-dimensional search but also finds the highest priority rule among all matching rules. Area-based quad-trie is a very good algorithm that constructs a two-dimensional trie using source and destination prefix fields. However, it performs the linear search for the prefix length, and hence it does not show very good search performance. In this paper, we propose to apply binary search on length to the area-based quad-trie algorithm. In improving the search performance, we also propose two new algorithms considering the priority of rules in building the trie.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.6
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• pp.17-24
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• 2011

In this paper, we propose an Entropy-based Routing Protocol using Mobility (ERPM) for supporting ubiquitous convergence services efficiently in mobile ad-hoc wireless networks. The main features that the ERPM introduces to obtain the goals can be summarized as follows. First, ERPM can construct stable routing routes based on the entropy concepts using mobility of nodes. Second, ERPM can quantitatively evaluate the stability of route by entropy concepts using mobility of nodes. Third, ERPM can select the most stable route in the view points of mobility of routes between a source node and a destination node, where multiple paths are available. The performance evaluation of the proposed ERPM performed via simulation using OPNET and analysis shows that the ERPM can support the construction of stable routing routes and increase the transmission ratio of data efficiently.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.2 no.1 s.2
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• pp.85-92
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• 2003

Due to the expansion of freeway networks in Korea, drivers have more routes to choose. Traffic information on various alternative roadway sections and routes may help drivers choose the optimal route that minimizes travel time or cost. Traffic information on roadways is, therefore, invaluable in sense that individual drivers could reduce their travel time or cost by selecting optimal routes, and furthermore total travel cost of the system could be lowered. However, consensus about the price of traffic information that drivers are willing to pay is not made yet. Current price of traffic information is decided according to the price of similar information such as stock, weather and so on. To investigate the value of traffic information, a survey was conducted at freeway rest areas near Seoul Megalopolis area including Kyunggi Province. Eight hundred drivers who had travelled on freeway within a year were randomly selected. Purposive Quota Sampling was used. A price-response function, a relationship between price and sales, was obtained based on the survey, followed by sensitivity analysis

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.5
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• pp.69-76
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• 2016

In this paper, we investigate the system performance of a cooperative relaying system of Non-orthogonal multiple access (NOMA) with successive interference cancellation (SIC), which is considered promising application in fifth generation (5G) cellular networks. Previous studies have focused on the selected relays, however we include the maxmin relay selection and derive analytical outage probability of opportunistic incremental relaying systems. For the realistic mobile environment, the distributions of relays are modeled as a homogeneous Poisson point process (PPP). And maximal ratio combining (MRC) is adapted to improve the system performance at the destination node. Analytical results demonstrate the outage probability improves with the near/far user power ratio, and the cooperative relaying scheme can achieve low outage probability in comparison to the no relaying scheme. It is also conformed that the increase of the intensity of PPP cause higher gains of the spacial diversity and hence the performance improves.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.2
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• pp.29-34
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• 2008

In this paper, we proposed a system protocol for detecting injurious insect to support energy saving transmission in wireless bio sensor networks. The main ideas and features of the system are as follows. First, the route establishment method which is based on the energy efficiency and stability by using time-division tree structure. Second, multi-hop direction-based data gatering structure. In this structure, the selected fading method is used to transmit packet via the established tree structure for supporting power saving and route lifetime efficiently. Finally, we can get the node power saving and reduce transmission delay, thus network lifetime and efficiency are improved. The performance evaluation of the proposed protocol is via OPNET(Optimized Network Engineering Tool).