• Journal of Korean Society of Transportation
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• v.29 no.6
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• pp.7-16
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• 2011

This study investigates the degree of dependency on freeways when auto travelers make route choices in the Seoul Metropolitan Area. The investigation is conducted based on aggregated auto trip data, defining the degree of dependency as the proportion of auto trips selecting freeways in their travel paths. The analyses reveal that the trips departing from the areas with higher accessibility to freeways tend to exhibit higher dependency on freeways. In addition, the dependency is significantly affected by the travel time differences between two paths including and excluding freeways, respectively. The number of service interchanges was found to be one of significant factors for trips to Incheon and Gyenggi areas. The finding indicates that the factors affecting the degree of dependency on freeways may vary depending on the areas' characteristics. The findings would enhance the understanding of drivers' route choice behavior in Seoul at an aggregate level.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.21
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• pp.9355-9360
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• 2014

Background: Oral squamous cell carcinoma (OSCC) remains as one of the most difficult malignancies to control because of its high propensity for local invasion and cervical lymph node dissemination. In this study, we evaluate the efficacy of our novel pH and temperature sensitive doxorubicin-methotrexate-loaded nanoparticles (DOX-MTX NP) in affecting HER2 expression profile in OSCC model in rat. Results: DOX-MTX- nanoparticle complexes caused significant decrease in mRNA level of HER2 compared to untreated cancers (p<0.05) and this finding was more pronounced with the IV mode (p<0.000). Surprisingly, HER2 mRNA was not affected in DOX treated as compared to the control group (p>0.05). On the other hand, in the DOX-MTX NP treated group, fewer tumors characterized with advanced stage and decreased HER2 paralleled improved clinical outcome (P<0.05). Moreover, the effectiveness of the oral route in the group treated with nanodrug accounted for the enhanced bioavailability of nanoparticulated DOX-MTX compared to free DOX. Furthermore, there was no significant difference in mRNA level of HER2 (p>0.05). Conclusions: Influence of HER2 gene expression is a new feature and mechanism of action observed only in dual action DOX-MTX-NPs treated groups. Down-regulation of HER2 mRNA as a promising marker and prognosticator of OSCC adds to the cytotoxic benefits of DOX in its new formulation. Both oral and IV application of this nanodrug could be used, with no preferences in term of their safety or toxicity. As HER2 is expressed abundantly by a wide spectrum of tumors, i DOX-MTX NPs may be useful for a wide-spectrum of lesions. However, molecular mechanisms underlying HER2 down regulation induced by DOX-MTX NPs remain to be addressed.

• Spatial Information Research
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• v.19 no.3
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• pp.43-52
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• 2011

Recently, interest in location-based service (LBS) which utilizes a DBMS in mobile system environment has been increasing, and it is expected to overcome the existing file-based system's limitation in advanced in-vehicle system by utilizing DBMS's advantages such as efficient storage, transaction management, modelling and spatial queries etc. In particular, the road network data corresponds to the most essential domain in a route planning system, which needs efficient management and maintenance. Accordingly, this study aims to develop an efficient graph-based geodata model for topological network data and to support dynamic path computation algorithm based on heuristic approach in mobile LBS system. To achieve this goal, we design a data model for supporting the hierarchy of network, and implement a path planning system to evaluate its performance in mobile LBS system. Last but not least, we find out that the designed path computation algorithm with hierarchical graph model reduced the number of nodes used for finding and improved the efficiency of memory.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.3
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• pp.3-9
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• 2013

As interest in green growth picks up, the importance of bicycles which are an environment friendly means of communication has been magnified. However, bicycle routes which are the base of bicycles are designed without considering topographic elements and thus many users are experiencing inconvenience in using bicycles. The present study presents a routing technique to select optimal routes when selecting routes in commuting to school utilizing bicycles. To this end, a formula for optimum route calculation considering slope and intersections was drawn and a method to select optimum routes by applying modified Dijkstra Algorithms was studied. According to the results, the bicycle routes for commuting to school should be selected by the shortest time rather than the shortest distances to the destination, because it required reach the destination faster. Therefore when selecting the routes, it must be based on the shortest time considering waiting time due to crosswalks or crossroads and speed variations due to slopes.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.8
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• pp.1080-1088
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• 2018

General methods of controlling a drone are divided into manual control and automatic control, which means a drone moves along the route. In case of manual control, a man should be able to figure out the location and status of a drone and have a controller to control it remotely. When people control a drone, they collect information about the location and position of a drone with the eyes and have its internal information such as the battery voltage and atmospheric pressure delivered through telemetry. They make a decision about the movement of a drone based on the gathered information and control it with a radio device. The automatic control method of a drone finding its route itself is not much different from manual control by man. The information about the position of a drone is collected with the gyro and accelerator sensor, and the internal information is delivered to the CPU digitally. The location information of a drone is collected with GPS, atmospheric pressure sensors, camera sensors, and ultrasound sensors. This paper presents an investigation into drone control by a remote computer. Instead of using the automatic control function of a drone, this approach involves a computer observing a drone, determining its movement based on the observation results, and controlling it with a radio device. The computer with a Depth camera collects information, makes a decision, and controls a drone in a similar way to human beings, which makes it applicable to various fields. Its usability is enhanced further since it can control common commercial drones instead of specially manufactured drones for swarm flight. It can also be used to prevent drones clashing each other, control access to a drone, and control drones with no permit.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1B
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• pp.68-77
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• 2010

Wireless sensor networks are installed in various environments and collect sensing data through wireless links. The quality of a wireless link may be unstable due to environment causes and hardware performance in wireless sensor networks. Since the change of the link quality may cause data loss, sensor nodes need to adaptively estimate the change of the link quality. Also, the routing protocol should deal with this situation. In this paper, the adaptive link quality estimation and routing scheme in the large-scale wireless sensor networks are proposed. When the quality of a link is unstable, sensor nodes agilely estimate the quality of links, and the new route is selected. When quality of a link is stable, the link quality is occasionally estimated so that the energy consumption is reduced. Moreover, sensor nodes exchange less beacons in order to reduce an overhead in dense networks. In the case of sparse network, the sensor nodes exchange more beacons for finding a better route. We prove that the proposed scheme can improve the energy efficiency and reliability.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.824-829
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• 2016

Passenger casualties in the case of ship accidents have increased because of the increase in size and complexity of current ships (such as cruise ships). Therefore, in recent years, emergency evacuation systems are receiving increased interest so as to ensure the safety of passengers. Currently, there are only basic instructions provided, such as announcements regarding the situation, alarms, and exit signs; however, no guidance toward a proper escape route has yet been provided. To solve this problem, several emergency guiding schemes have been proposed. However, these systems ignore some of the realities of ship accidents and are impractical because various risk factors are not considered. Therefore, this paper proposes an optimal route guiding system based on an $A^*$ algorithm for emergency escape during disaster situations. This system takes into account various possible risk factors. Performance evaluation using computer simulations showed that the proposed scheme is effective and leads to safe escape routes.

• Journal of the Korean Society for Railway
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• v.18 no.2
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• pp.149-156
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• 2015

It is necessary to determine real path for urban railway users in order to allocate revenues between urban railway organizations. Out of several algorithms used to determine optimal routes, the k-path algorithm based on link-label has been utilized. However, this k-path algorithm has certain flaws. For example, optimal route can change depending on the travel and walking time, transfer penalty, and so on. Also, this algorithm cannot take into account the characteristics of users, who prefer express train to normal trains. In this paper, an algorithm is proposed to determine one single optimal route based on the traffic card data. This method also can search for an optimal path in conjunction with the railway timetable.

• Archives of design research
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• v.19 no.2 s.64
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• pp.81-90
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• 2006

Pedestrians perceive differently from the sideway views or the exteriors of the buildings on the way to their destinations. Therefore, the navigation experience can become much different when the path was chosen based on the individual's preference from it is not. By focusing on the effects of the individual pedestrian' path choice on their navigation, this paper presents an algorithm designed for pedestrians to be able to explore their preferred path and proposes a prototype of navigation system based on the algorithm. The navigation support system searches for the best path upon their individual preferences and information of the destination. The system provides the process of retrieving the final path via the pedestrian-support system interaction. The path retrieval is peformed with the combinational matrix of keywords that are formulates Fuzzy theory from the correlations between the terms describing preferences used in the path preference survey. This paper presents the potentials of the path finding method tailored to pedestrians' preferences by a simulation of the proposed path retrieval algorithm.

• KIPS Transactions on Software and Data Engineering
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• v.9 no.1
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• pp.17-24
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• 2020

The traveling salesman problem is an algorithmic problem tasked with finding the shortest route that a salesman visits, visiting each city and returning to the started city. Due to the exponential time complexity of TSP, it's hard to implement on cases like amusement park or delivery. Also, TSP is hard to meet user's demand that is associated with multi-dimensional attributes like travel time, interests, waiting time because it uses only one attribute - distance between nodes. This paper proposed Top-n Skyline-Multi Dimension TSP to resolve formerly adverted problems. The proposed algorithm finds the shortest route faster than the existing method by decreasing the number of operations, selecting multi-dimensional nodes according to the dominance of skyline. In the simulation, we compared computation time of dynamic programming algorithm to the proposed a TS-MDT algorithm, and it showed that TS-MDT was faster than dynamic programming algorithm.