• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.8
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• pp.3060-3069
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• 2010

LBS is service technique to provide several service which are required to user by user's location information for mobile. This paper presents Auto_Test system of testing the mobility performance of mobile clients in wireless mobile networks. In spite of importance of mobility management, currently the study of mobility management is not enough, therefore we have developed modulated Auto_Test management system for resolve the mobility management. The proposed system is composed of distance-based monitoring, location-based monitoring, scenario management, mobility management and statistic management, it makes the control by individual module. Simulation results show that the proposed system outperforms the existing systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7B
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• pp.760-770
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• 2011

The existing mobility management schemes do not fully support the next generation network, which is composed of IP-based core network and various access networks. Currently, ETRI has been developing the AIMS (Access Independent Mobility Service) system which satisfies the ITU-T requirements of mobility management in the next generation network. The AIMS system is designed to provide a mobile host with a fast and reliable mobility service among heterogeneous access networks. Recently, many user devices have multiple communication interfaces, e.g., 3G and WLAN, and thus they can make two or more network connections at the same time. In this paper, we design a scheme of flow mobility, i.e., the movement of selected data flows from one access technology to another, to be applied in the AIMS system, and verify the proposed scheme through the NS-3 simulation study. From the simulation results, we can know that the proposed flow mobility scheme can utilize the network resource efficiently in the heterogeneous mobile networks.

• Journal of Industrial Technology
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• v.28 no.B
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• pp.245-250
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• 2008

Recently, mobile devices have supported wireless LAN as well as bluetooth, where the services such as heterogeneous network access and seamless mobility connection are important. Even though the mobility and physical network might be varied, an efficient communication mechanism for the network access and a robust mobility management of mobile devices are needed. In this paper, we design and implement a Bluetooth system with mobile LAN access capability. The proposed system has the following features; 1) IP connection is enabled by BENP in the link layer, 2) The networks devices of heterogeneous mobile devices are integrated into a single virtual network interface, 3) IP mobility between the bluetooth and wireless LAN is supported by mobile IP. The experimented results show that the packet loss and delay time during the handover duration is reduced by predicting the handover among different networks followed by the setup of any required parameters in advance.

• International Journal of Advanced Culture Technology
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• v.1 no.2
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• pp.7-12
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• 2013

Mobility management is an important issue in Mobile Ad Hoc Networks (MANETs) because location information of mobile nodes is frequently changed and it aggravates the performance in MANETs drastically. In this paper, we propose a fuzzy logic based mobility management scheme using group quorum system by considering the mobile nodes' locality in order to manage location information of mobile nodes in MANETs efficiently. The proposed scheme selects mobility databases adaptively from group quorum system by considering the degree of locality of a mobile node. The performance of the proposed scheme is evaluated by an analytical model and compared with that of existing mobility management scheme.

• Korean Management Science Review
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• v.23 no.1
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• pp.21-41
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• 2006

Given the growing deployment of mobile offices, we need to understand the fectors which affect their successful use and implementation. We in this paper present a parsimonious model which integrates the IS success model and the TAM. The main feature of the model is that it allows one to explore the role of mobility of mobile office systems in determining the level of system usage and dependence. Although the mobility is the key property of any mobile system, there is little research effort exerted to understand how mobility affects the traditional IS factors such as perceived ease of use and usefulness. In addition to the system usage, this model also uses dependence as the dependent variable. This is expected to provide richer understanding of the study context. We collected survey data from 1,614 field service workers of a major domestic electronic company. They use PDAs to retrieve information regarding the specifics of the customer service requests and to report what has been done for each service job. The results from SEM analysis show that mobility improves the perceived ease of use which then leads the field service workers to depend more on the PDA systems. Interestingly enough, however, the workers' satisfaction does not cause more frequent use of the system.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.5
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• pp.480-488
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• 2006

Industrial and economical importance of CP(Cellular Phone) is growing rapidly. Combined with IT technology, CP is one of the most attractive technologies of today. However, unless we find a new breakthrough in the technology, its growth may slow down soon. RT(Robot Technology) is considered one of the most promising next generation technologies. Unlike the industrial robot of the past, today's robots require advanced features, such as soft computing, human-friendly interface, interaction technique, speech recognition object recognition, among many others. In this paper, we present a new technological concept named RCP (Robotic Cellular Phone) which integrates RT and CP in the vision of opening a combined advancement of CP, IT, and RT, RCP consists of 3 sub-modules. They are $RCP^{Mobility}$(RCP Mobility System), $RCP^{Interaction}$, and $RCP^{Integration}$. The main focus of this paper is on $RCP^{Mobility}$ which combines an autonomous navigation system of the RT mobility with CP. Through $RCP^{Mobility}$, we are able to provide CP with robotic functions such as auto-charging and real-world robotic entertainment. Ultimately, CP may become a robotic pet to the human beings. $RCP^{Mobility}$ consists of various controllers. Two of the main controllers are trajectory controller and self-localization controller. While the former is responsible for the wheel-based navigation of RCP, the latter provides localization information of the moving RCP With the coordinates acquired from RFID-based self-localization controller, trajectory controller refines RCP's movement to achieve better navigation. In this paper, a prototype of $RCP^{Mobility}$ is presented. We describe overall structure of the system and provide experimental results on the RCP navigation.

• Journal of Astronomy and Space Sciences
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• v.26 no.4
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• pp.677-692
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• 2009

In recent years, lots of studies on the planetary rover systems have been performed around space advanced agencies such as NASA, ESA, JAXA, etc. Among the various technologies for the planetary rover system, the mobility system, navigation algorithm, and scientific payload have been focused particularly. In this paper, the conceptual design for a ground-based model of planetary rover's mobility system to evaluate mobility and moving stability on ground is presented. The status of overseas research and development of the planetary rover systems is also addressed in terms of technical issues. And then, the requirements of the planetary rover's mobility system are derived by means of considering mobility and stability. The designed rover's mobility system has an active suspension with 6 legs that controls 6 joints on the each leg in order to achieve high stability and mobility. This kind of mobility system has already applied to the ATHELE of NASA for various purposes such as transportation and habitation for human lunar exploration activities in the near future (i.e., Constellation program). However, the proposed system has been designed by focusing on the small-sized unmanned explorations, which may be applied for the future Korea Lunar exploration missions. Therefore, we expect that this study will be an useful reference and experience in order to develop the planetary exploration rover system in Korea.

• Journal of Korean Institute of Industrial Engineers
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• v.29 no.2
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• pp.135-144
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• 2003

Traffic performance in a microcellular system is much more affected by cell dwell time and channel holding time in each cell. Cell dwell time of a call is characterized by its mobility pattern, i.e., stochastic changes of moving speed and direction. Cell dwell time provides important information for other analyses on traffic performance such as channel holding time, handover rate, and the average number of handovers per call. In the next generation mobile communication system, the cell size is expected to be much smaller than that of current one to accommodate the increase of user demand and to achieve high bandwidth utilization. As the cell size gets small, traffic performance is much more affected by variable mobility of users, especially by that of pedestrians. In previous work, analytical models are based on simple probability models. They provide sufficient accuracy in a simple second-generation cellular system. However, the role of them is becoming invalid in a picocellular environment where there are rapid change of network traffic conditions and highly random mobility of pedestrians. Unlike in previous work, we propose an improved probability model evolved from so-called Random walk model in order to mathematically formulate variable mobility of pedestrians and analyze the traffic performance. With our model, we can figure out variable characteristics of pedestrian mobility with stochastic correlation. The above-mentioned traffic performance measures are analyzed using our model.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.10a
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• pp.268-296
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• 2005

Given the growing expectations on the value and application of mobile office, we need to understand the factors which affect its successful use and implementation. We in this paper present a parsimonious model which integrates the IS success model and the TAM. The main feature of the model is that it allows one to explore the role of mobility of mobile office systems in determining the level of system usage and dependence. Although mobility is the key property of any mobile system, there is little research effort exerted to understand how mobility affects the traditional IS factors such as perceived ease of use and usefulness. In addition to the system usage, this model also uses dependence as the dependent variable. This is expected to provide richer understanding of the study context. We collected survey data from 1,614 field service workers of a major domestic electronic company. They use PDAs to retrieve information regarding the specifics of the customer service requests and to report what has been done for each service job. The results from SEM analysis show that mobility improves the perceived ease of use which then leads the field service workers to depend more on the PDA systems. Interestingly enough, however, the workers’ satisfaction does not cause more frequent use of the system.

• Journal of Sensor Science and Technology
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• v.33 no.2
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• pp.93-97
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• 2024

With the development of promising future mobility and urban air mobility (UAM) technologies, the demand for LIDAR sensors has increased. The SWIR photodetector is a sensor that detects lasers for the 3D mapping of lidar sensor and is the most important technology of LIDAR sensor. An SWIR photodetector based on QDs in an eye-safe wavelength band of over 1400 nm has been reported. QDs-based SWIR photodetectors can be synthesized and processed through a solution process and have the advantages of low cost and simple processing. However, the organic ligands of QDs have insulating properties that limit their ability to improve the sensitivity and stability of photodetectors. Therefore, the technology to replace organic ligands with inorganic ligands must be developed. In this study, the organic ligand of the synthesized PbS QDs was replaced with a MAPI inorganic ligand, and an SWIR photodetector was fabricated. The analysis of the characteristics of the manufactured photodetector confirmed that the photodetector based on MAPI-capped PbS QDs exhibited up to 26.5% higher responsivity than that based on organic ligand PbS QDs.