• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1544-1549
• /
• 2004

A new collision avoidance algorithm is presented for two mobile robots in narrow corridor environments. When two robots meet each other in a narrow corridor, one should yield the way to the other robot. To solve the problem arising in this situation, they exchange their path to get information about crossing-points to check avoidance conditions, which are necessary for choosing the robot to yield. The conditions are summarized as follows. 1) If one robot blocks the path to the closest crossing-point in front of the other robot. 2) If the closest crossing-point of each robot is the same point. 3) Which robot is closer to the closest crossing-point. In this paper, we propose a path planning algorithm for the robot which yield the way. Simulation results are presented to verify the feasibility of the proposed collision avoidance algorithm.

• Journal of Communications and Networks
• /
• v.18 no.2
• /
• pp.238-245
• /
• 2016

A sequence number checking technique is proposed to improve the performance of TCP connections in mobile ad hoc networks. While a TCP connection is initialized, a routing protocol takes the responsibility for checking the hop count between a source and destination pair. If the hop count is greater than a predefined value, the routing protocol decides to use a proxy node. The responsibility of a proxy node is to check the correctness of data packets and inform the missing packets by sending an acknowledgement from a proxy node to the source node. By doing so, the source node is able to retransmit any missing packet in advance without waiting until an end-to-end acknowledgement is received from the destination. Simulation results show that the proposed mechanism is able to increase throughput up to 55% in static network and decrease routing overhead up to 95%in mobile network.

• Management Science and Financial Engineering
• /
• v.13 no.2
• /
• pp.79-97
• /
• 2007

This paper investigates the relationship of service quality and user satisfaction in the wired and mobile Internet services based on the integrative framework of both systems. Given a moderate level of reliability and validity, the commonly driven dimensions for measuring service quality include responsiveness, assurance, empathy, convenience, usefulness, and diversity. User satisfaction is measurable by the dimensions of communication/entertainment, finance/economics, location/geography, and information/consulting. We apply the MANOVA tests to evaluate whether each of the service quality dimensions has an overall influence on user satisfaction. Next, multiple regression analyses are conducted to check if unique positive effect exists between each combination of service quality dimensions and user satisfaction dimensions. The results show that service quality must be taken care of with respect to the assurance dimension in order to enhance customer satisfaction in the dimensions of location/geography, which will contribute to increasing the utilization of mobile service. For improving user satisfaction in the dimension of information/consulting, service quality must be supported with respect to assurance and empathy in the mobile Internet market, in addition to diversity, which is the only significant service quality in the wired Internet service.

• Architectural research
• /
• v.19 no.1
• /
• pp.1-6
• /
• 2017

Over the past decade, building information modeling (BIM) has gained a foothold in the construction sector. However, as digital data generated in the virtual space of a computer environment, BIM-based data have an inherent limitation in their application efficacy under field conditions. To overcome this, the present study employs augmented reality (AR) to reduce the discrepancy between the digital data generated in virtual spaces and real-world conditions. We assessed the potential applicability of an AR-based interface by analyzing existing examples of Apple, Google, and Facebook, which reflect the recent developments of technologies focusing on user experience. We then proceeded with an AR study, restricting the scope of application to a mobile environment in which an efficient information transmission between a digital model and real life can take place. Object-oriented software engineering was employed to ensure an efficient implementation of a BIM-based AR system for campus space management (CSM) in a mobile environment. Finally, we conducted a module test to check the reliability of the CSM method by using an AR-based mobile system with a prototype of the model used in university campuses, and extracted and itemized the supplementary requirements for CSM by using BIM tools for running AR applications.

• ETRI Journal
• /
• v.36 no.1
• /
• pp.51-61
• /
• 2014

In the Mobile IPv6 (MIPv6) protocol, a mobile node (MN) is a mobile device with a permanent home address (HoA) on its home link. The MN will acquire a care-of address (CoA) when it roams into a foreign link. It then sends a binding update (BU) message to the home agent (HA) and the correspondent node (CN) to inform them of its current CoA so that future data packets destined for its HoA will be forwarded to the CoA. The BU message, however, is vulnerable to different types of security attacks, such as the man-in-the-middle attack, the session hijacking attack, and the denial-of-service attack. The current security protocols in MIPv6 are not able to effectively protect the BU message against these attacks. The private-key-based BU (PKBU) protocol is proposed in this research to overcome the shortcomings of some existing MIPv6 protocols. PKBU incorporates a method to assert the address ownership of the MN, thus allowing the CN to validate that the MN is not a malicious node. The results obtained show that it addresses the security requirements while being able to check the address ownership of the MN. PKBU also incorporates a method to verify the reachability of the MN.

• Convergence Security Journal
• /
• v.11 no.3
• /
• pp.75-84
• /
• 2011

With the rapid development of mobile technology the use of smartphone is spreading. In order to activate mobile banking and market in the future, the most important key is a secure financial transactoin. However, because many apps are developed without security check in proportional to the spread of smartphone, security threat is inevitably high. Current smartphone banking is processed as the way of the existing public certificate or OTP technique in the mobile environment, but many security hole about current technology is pointed out steadily. Therefore, in this paper we are to improve a existing security hole by reinforcing the security through multi-factor authentication and providing a physical non-repudiation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2011.10a
• /
• pp.749-752
• /
• 2011

According to the increasing of smart-phones, major department stores and large discount stores are releasing some new applications. However, these applications remain based on existing webs tailored to only mobile devices. This document describe the development of a shopping planner system that allows customers to access retail stores through mobile services and check the present availability of a product on-line. The system marks a product location on the map of a big market, stating if a product is on sale or not. Also, it enables customers to distinguish goods without buying from their scheduled purchasing. Through these functions, customers can find products they want to buy more easily and quickly. Furthermore, they don't have to look a staff member to check the products' location or stock quantity.

• Environmental Analysis Health and Toxicology
• /
• v.30
• /
• pp.15.1-15.11
• /
• 2015

Objectives There has been a growing concern about the possible carcinogenic effects of the electromagnetic radiofrequency fields emitted from mobile phones. The purpose of this study was to investigate the association between mobile phone use and the development of gliomas in Korea. Methods Our study methods were based on the International Interphone study that aimed to evaluate possible adverse effects of mobile phone use. This study included 285 histologically-confirmed Korean patients 15 to 69 years of age, with gliomas diagnosed between 2002 and 2007 in 9 hospitals. The 285 individually matched controls were healthy individuals that had their medical check-up in the same hospitals. Unconditional logistic regression was used to calculate the adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for use of mobile phones. Results For the entire group, no significant relationship was investigated between gliomas and regular use of mobile phones, types of mobile phones, lifetime years of use, monthly service fee, and the other exposure indices. Analyses restricted to self-respondents showed similar results. For ipsilateral users, whose the body side for usual mobile phone use match the location of glioma, the aORs (95% CIs) for lifetime years of use and cumulative hours of use were 1.25 (0.55 to 2.88) and 1.77 (0.32 to 1.84), respectively. However, the contralateral users showed slightly lower risk than ipsilateral users. Conclusions Our results do not support the hypothesis that the use of mobile phones increases the risk of glioma; however, we found a non-significant increase in risk among ipsilateral users. These findings suggest further evaluation for glioma risk among longterm mobile phone users.

• Journal of Institute of Control, Robotics and Systems
• /
• v.11 no.5
• /
• pp.463-470
• /
• 2005

This paper describes a method aimed at improving dead-reckoning accuracy with gyroscopes in mobile robots. The method is a precision calibration procedure for gyroscopes, which effectively reduces the ill effects of nonlinearity of the scale-factor and temperature dependency. This paper also describes the methods of gyro data collection fur all ambient temperature$(-40^{\circ}C{\~}+80^{\circ}C)$ using cubic spline interpolation and defining the error function. The sensor used was a vibrating gyroscope called the EWTS82NA21, which is low lost and commonly used in car navigation system, made by Panasonic. This angular rate sensor utilizes Coriolis force generated by a vibrating tuning fork. The paper also provides experimental results to check the performance and the effectiveness of the proposed method.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.21 no.6
• /
• pp.744-750
• /
• 2015

In this paper, development of mobile robot for the inspection of hull surface was mentioned. In the sea, it is difficult to proceed with the visual inspection of hull side and thus mobile robot for checking the status could be run with strap-on its surface. To do this, permanent magnet module to generate magnetic force between hull surface and mobile robot, and structure to minimize variance of the force under curvature circumstance were considered on the design. Based on the design, mobile robot with four NdFeB, four driving wheels and image aquisition module was applied. Load experiment to check the adhesive force, slip test during stop state and driving test to measure driving speed were executed. From the experiments 13 Kgf adhesive force was obtained and slip was not happened until 8 Kgf load on the inclined plate. Driving speed of mobile robot was measured at 0.82 m/s corresponding to 6.5 ampere. We confirmed the effectiveness of developed mobile robot by experiments to check its characteristics.