• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.3
• /
• pp.25-31
• /
• 2015

In this paper, we propose PEP based on cross-layer and network coding in digital video broadcasting-return channel via satellite (DVB-RCS) networks. In particular, we propose not only a scheme of cross-layer information exchange for interaction between TCP and the resource allocation (RA) scheme in the link layer but also a tuning algorithm for the TCP contention window (CWND) by using information on the RA in the link layer and the redundancy rate for network-coded packets. The simulation results show that TCP CWND can be adjusted by RA information in the proposed protocol. Furthermore, through the transmission of network-coded packets and the proposed CWND tuning algorithm, TCP throughput is enhanced in lossy environment due to user mobility without the unnecessary resource overhead.

• 한국HCI학회:학술대회논문집
• /
• 2006.02b
• /
• pp.215-220
• /
• 2006

오늘날 우리는 모바일 기기의 눈부신 성장과 보급으로 인해 누구나 손쉽게 모바일 게임을 즐길 수 있게 되었다. 많은 게임 제작 업체들은 모바일 게임개발에 총력을 기울이고 있고, 단말기 제조업체들 역시 게임 전용폰을 출시하는 등 모바일 게임에 대한 호응이 고조되고 있는 상황이다. 이는 모바일 게임이 시간과 공간적 개념을 뛰어넘는 이동성(Mobility)이라는 큰 장점을 가지고 있기 때문이다. 그러나 이러한 장점에도 불구하고 현재까지 모바일 게임의 컨텐츠는 기존의 다른 게임에 비해 그다지 큰 차별성을 가지고 있지 않다. 고스톱이나 단순한 퍼즐게임 등이 호응을 얻고 있기는 하지만 '이동성' 이라는 큰 장점을 살리기 위해서는 거 적극적이고 새로운 개념의 접근이 필요하기 때문이다. 더구나 요즘은 PSP 와 같은 막강한 휴대용 게임기가 등장하면서 휴대폰에서 즐기는 모바일 게임은 작은 화면이나 낮은 메모리 등의 한계로 인해 점점 더 그 자리를 내어주고 있는 실정이다. 그렇다면 '이동성'을 적극적으로 활용할 수 있는 모바일 개임 제작에 대한 새로운 접근방식은 어떻게 이루어져야 할까? 이를 위한 효과적인 방법으로 본 논문에서는 게임의 무대를 우리가 살고 있는 '현실-Reality'로 옮겨 올 것을 제안한다. 그렇게 되면 게이머는 모바일 기기가 가진 제약에서 벗어나 그 자신이 직접 현실세계를 배경으로 한 게임캐릭터가 되고, 물리적 이동에 따라 게임이 진행되는 전혀 새로운 방식의 모바일 게임을 경험할 수 있게 될 것이다. 현재 국내외적으로 이러한 실험적 시도가 조금씩 이루어지고 있기는 하지만 아직 호응은 그리 높지 않다. 그리하여 본 논문에서는 그러한 사례들을 조망하고 가장 효과적인 방법을 국내의 현실에 적합하게 적용할 새로운 모바일 게임의 방식을 제안하고자 한다. 연구사례로 제안 할 모바일 게임은 인터넷 미니홈피, GPS, 멀티미디어 메시지, 카메라 폰, 전자상거래의 기능을 통합하여 활용하는 'Dice Adventure Meeting'이라는 이름의 모바일 미팅 게임이며, 게임의 구체적인 시나리오를 살펴보면서 현실을 배경으로 한 새로운 모바일 개임의 제작에 대한 접근방법을 제시하고자 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2007.10a
• /
• pp.75-78
• /
• 2007

Mobile IP provides hand-held devices with mobility which allows the user to do work over the network. However, handover time due transfer between access routers causes network delays and data loss. L2Trigger Handover expects this handover to take place, and executes L3 handover before L2 handover takes place, thereby reducing overall handover latency, although it still is an issue since handover latency between AR is not completely eliminated in L2 trigger handover. In this paper took into consideration where MIH is used in MIPv4 and using MIH Table when handover is about to occur in MN(Mobile Node), thereby pre-fetching data needed by Handover. In this way, when the handover is estimated, it improves the init time that L2trigger had. Furthermore we can find that we can execute the handover with shorten init time in smaller and narrow overlap length

• The KIPS Transactions:PartD
• /
• v.12D no.4 s.100
• /
• pp.521-530
• /
• 2005

Many researches are going on with regard to issues and problems related to mobile database systems, which are caused by the weak connectivity of wireless networks, the mobility and the Portability of mobile clients. Mobile computing satisfies user's demands for convenience and Performance to use information at any time and in any Place, but it has many Problems to be solved in the aspect of data management. The purpose of our study is to design Mobile Query Processing System(MQPS) to solve problems related to database hoarding, the maintenance of shared data consistency and the optimization of logging, which are caused by the weak connectivity and disconnection of wireless networks inherent in mobile database systems under mobile client-server environments. In addition, we proved the superiority of the proposed MQPS by comparing its performance to the C-I-S(Client-Intercept- Server) model.

• Smart Media Journal
• /
• v.9 no.3
• /
• pp.71-79
• /
• 2020

Mobile network is used by many users worldwide for diverse services, including phone-call, messaging and data transfer over the Internet. However, this network may experience massive damage if it is exposed to cyber-attacks or denial-of-service attacks via wireless communication interference. Because the mobile network is also used as an emergency network in cases of disaster, evaluation or verification for security and safety is necessary as an important nation-wide asset. However, it is not easy to analyze the mobile core network because it's built and serviced by private service providers, exclusively operated, and there is even no separate network for testing. Thus, in this paper, a virtual mobile network is built using OpenAirInterface, which is implemented based on 3GPP standards and provided as an open source software, and the structure and protocols of the core network are analyzed. In particular, the S1AP protocol messages captured on S1-MME, the interface between the base station eNodeB and the mobility manager MME, are analyzed to identify potential security threats by evaluating the effect of the messages sent from the user terminal UE to the mobile core network.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.4C
• /
• pp.441-450
• /
• 2006

WiBro(Portable Internet Service) is service being capable to provide a high data rate wireless internet access with Personal Subscriber Station under the stationary or mobile environment, anytime and any where. It will fill the gap between very high data rate wireless local area networks and very high mobility cellular systems. The security is an important point of WiBro providing high data and mobile wireless services. This paper proposes user authentication mechanism of WiBro wireless networks applied EAP-AKA authentication protocol. As a result of Wireless authentication based on EAP-AKA, this mechanism is capable to be used in WiBro-WLAN-3GPP interworking scenario as well as the WiBro authentication mechanism.

• Journal of Internet Computing and Services
• /
• v.7 no.5
• /
• pp.43-57
• /
• 2006

Next-generation mobile communication systems evolve in the form of high speed data transmission along with integration of wired-wireless network. Therefore, it needs researches on integrating service to heterogeneous networks to offer high speed data transmission and various services while supporting user mobility. In existing studies, heterogeneous networks are linked to single core network separatively, Since vertical handoff between heterogeneous networks leads to some delay, packets may be lost during vertical handoff. To solve this problem, this paper proposes an hierarchically integrated network architecture considering the characteristics of CDMA2000, WiBro, and WLAN. The hierarchically integrated networks are overlaid according to coverage of each network. Therefore, the proposed architecture can minimize handoff delay and packet loss. In addition, this paper proposes an integrated framework for next generation mobile communication networks.

• Journal of Korea Society of Industrial Information Systems
• /
• v.18 no.6
• /
• pp.83-94
• /
• 2013

As smart devices have proliferated and mobile networks have accelerated, various wired IT(Information Technology) services are transplanted in wireless environments. Cloud computing service, enabling individual users or firm users to download data from a server and upload data after manipulating data, is also available in mobile devices. Unlike cloud service in wired network environments, mobile cloud service provides differentiated aspects in mobility, security issues caused by persistent connection to networks. In this paper we aim to analyze the factors affecting the user attitude and their structural relationships towards mobile cloud service use. We extend TAM(Technology Acceptance Model) to consider the characteristics of mobile environments. Research findings, analyzed by SEM(Structural Equation Model), are explained and practical implications are presented with concluding remarks.

• Journal of the Korea Furniture Society
• /
• v.22 no.3
• /
• pp.190-198
• /
• 2011

This study intended to present a new direction of differentiated and innovative furniture design for small living space overcoming the uniformity of conventional small living. In order to achieve these goals, a new piece of furniture with multi functions useful for such small space has been designed and explained in this study. This new type multi-functional furniture can be utilized as kitchen, dining table, home bar or office stand depending on the user's necessity. In particular, it provides more adaptability to changing life and spatial availabilities for small living space in terms of space division, separation and fusion features. Based on the needs of small living space brought by social changes, the conventional concept of small living space, which divides space by partitions or walls, should be changed into flexible perception of space. Also, this research proposed the features of furniture design for functional shifts in terms of its functional, structural, and systematical aspects. In this respect, space can be regarded as a variable place and the image of space can be differently appreciated by means of shift, functional transition and mobility. That is, small living space can be perceived as kitchen, living space or working space at the same time. In conclusion, the versatile use of limited space can be a solution to the issues related to small living space; the convertible and movable furniture called F4 Island presented in this study can transform such spatially limited space into a space with multiple functions to meet the requirements of its residents.

• Journal of Korean Society for Geospatial Information Science
• /
• v.19 no.3
• /
• pp.13-21
• /
• 2011

In mobile environment supporting mobility technologies, user requirements have been increased with respect to utilization of location information. In particular, moving object DBMS has consistently posed in order to efficiently maintain traffic information related to location of vehicle which tents to tremendously change over time. Despite the fact that these sorts of researches must be taken into consideration, empirical studies on moving object in terms of map database for lbs service, spatial attribute of which is continuously changed over time, have rarely performed. Therefore, aim of this paper is to suggest efficient spatial index scheme, which is capable of supporting query processing algorithm and location of moving object over time, by developing new empirical model. As a result, we can come to the conclusion that moving object model based on multi-fixed grid index makes it possible to cut down on the number of entity for retrieving. What's more, this model enables hierarchical data to be accessed through efficient spatial filtering on large-scale lbs data and constraints in accordance with level in order to display map.