• Journal of Korea Multimedia Society
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• v.12 no.1
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• pp.156-167
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• 2009

Computing environment is evolving rapidly to ubiquitous environment. It thus makes people access and utilize any resource on the move and makes location of objects rise to the rank of the most important information. However provision of location information is too restrictive in small environments such as a home or building. In this paper we propose a home entertainment system which supports user mobility based on sensor networks and distributed devices. The proposed system estimates a user location by using signal strength received from Bluetooth ad-hoc networks. This estimated location information can tell which device a user can take advantage of while moving. In order to prove possibility of user mobility support, the system is implemented on our UPnP A/V framework home entertainment system to provide content streaming and the result shows that a provision of service for mobile users could be possible in small ubiquitous computing environments.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.424-429
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• 2008

The purpose of this research is to suggest a competitive design by producing functions and elements needed to users based on a research about device use and needs according to user behavior. We proceeded to the research aiming a design smart document-editing device design which can be used for business regardless of place (at office or home), targeting reasonable and individualistic users from twenties to thirties. By some ways for that, first, we selected target users and based on user interviews to get enough understanding for them. Second, we produced user needs by some troubles after establishing persona and deciding target users on the basis of the research. Third, we designed form-factor visualizing work, organized design spec by the produced concept, and we developed interaction design on the basis of this scenario. Fourth, we made paper prototype and conducted user test. As a result, our final design emphasizes mobile ability and simplicity to be suitable for reasonable individualism and is able to efficiently work input, editing, and output without complicated procedure. We could also prove the validity of the design through usability test.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.1
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• pp.139-144
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• 2009

As it got through the step of super-high speed internet, mobile and digital convergence, the Ubiquitous Society is being attained gradually. Now, it is being variously spread not only the little ordinaries of communication but also fields of economy and industry. Specially, RFID and Navigation system are being used at home and foreign. These are prospected to give assistances that it brings along the competitive power of nation. But inflection range of RFID and Navigation is localized in the most simplest. This paper proposes system to reflect the individual and special quality using RFID and Navigation and to fit easily changing environment. And we studied to use what kind of information in the special environment. We used Fuzzy Logic and TSP for making the intelligence path searching and guiding system with more information.

• The KIPS Transactions:PartC
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• v.18C no.3
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• pp.195-198
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• 2011

Recent expansion of the ubiquitous environment and improvement of the USN give lots of U-healthcare systems. In this paper, we design and implement a wireless ECG measurement system that can send ECG signals among the sensors and collector. It can also give almost the same precision as a hospital ECG system with mobility. The most important fact of the mobile ECG system is the signal data connectivity among the sensors and device such as signal cables or wires. we can eliminate the signal cable through the Zigbee sender and collector via implementing Zigbee-SD communication system that can receive the ECG signal data. We also implement ECG app software on the smart phone that can analyze and show the data results directly. It can give lots of mobility and usability under ubiquitous environment and would be a very efficient wireless ECG system for U-healthcare service.

• Journal of Internet Computing and Services
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• v.12 no.4
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• pp.15-26
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• 2011

As quick and secure mobility service is becoming a critical issue in the ubiquitous environment. Internet Engineering Task Force (IETF) has done a lot of meaningful work in order to cope with the critical issues, which is a key technology of guaranteeing the legally and safely using of network resources, they has proposed Hierarchical Mobile IPv6 (HMIPv6) to complement for such problems as handover latency and signaling overhead in existing MIPv6. Most of the current research about HMIPv6 focuses on how to optimize the interactive processes between the HMIPv6 and AAA (Authentication, Authorization, Accounting) protocol. This paper describes a cost-effective hierarchical authentication scheme, which makes its focus on minimizing the authentication latency in AAA processing. In this scheme, a hierarchical AAA architecture is proposed, in which the AAA servers are deployed on the Mobility Anchor Point (MAP), the Root AAA server manages several Leaf AAA servers and the Brokers on behalf of the AAA server in home domain. The simulation results shows that the proposed scheme reduces the handoff and authentication latency evidently compared to the previous traditional authentication combination modeling.

• The KIPS Transactions:PartC
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• v.15C no.5
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• pp.343-350
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• 2008

In ubiquitous environment, a user has been provided with service and mobility using various devices. The users' network can be divided into a home network (a user belongs to the network through an authentication server) and an external network (when a user moves or external authentication server is). Users can use a mobile device or a device at an external network. In this paper, when a user has access to a service in an external network with a mobile device, there is a skim that a service is securely provided by roaming private information (encryption key etc${\cdots}$) and a skim which gives access to a home network using a device in an external network. If you use these skims, roaming is provided in order that you can use a secure service in an external network.

• Journal of IKEEE
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• v.12 no.1
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• pp.18-26
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• 2008

With the advent of Ubiquitous environment, wired-wireless combination network is being studied very actively in which mobile nodes having multi-hop communication capability connect wired internet network easily, and shares the information. The study of wired and wireless combination network between MANET(Mobile Ad Hoc Network) and wired network is being focused only on the configuration of heterogeneous network interface. The proposed algorithm establishes independent multi-paths between source node and destination node to prevent data loss when errors happen in route. As the result, it shows that the reliability of the combination network can be improved by making data transmit continuously on the route error.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.2
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• pp.91-99
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• 2009

Mobile WiMAX is an emerging technology that can provide ubiquitous Internet access. To provide seamless service in mobile WiMAX environment, delay or disruption in dealing with mobility must be minimized. However offering seamless services on IEEE 802.16e networks is very hard due to long handover latency both in layer 2 and 3. In this paper, we propose a fast cross-layer handover scheme based on prediction algorithm. With the help of the prediction, layer-3 handover activities are able to occur prior to layer-2 handover, and therefore, total handover latency can be reduced. The experiments conducted with system parameters and propagation model defined by WiMAX Forum demonstrate that the proposed method predicts the future signal level accurately and reduces the total handover latency.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.64-75
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• 2007

Service discovery protocols is software components to find specific services or resources on network. The SLP defined by IETF protocol is a framework for automatic service discovery on IP based networks. Automatic service discovery is an important component on ubiquitous computing environment. This paper proposes a service discovery architecture named as SLPA(Service Location Protocol based on AMAAM). AMAAM(Mobility Agent Advertisement Mechanism) is an aggregation-based Mobile IP implementation in MANET. In SLPA, the role of the directory agent is assigned to the mobility agent in AMAAM. The mobility agent periodically beacons an advertisement message which contains both the advertisement of the directory agent in SLP and the advertisement of the mobility agent in Mobile IP. For evaluating the functional correctness of SLPA and the overhead of maintaining a service directory of SLPA. We simulate SLPA using ns-2 and analyze the overhead of control overheads for the aggregation. Through the simulation experiments we show the functional correctness of the proposed architecture and analyze the performance results.

• Journal of Digital Contents Society
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• v.8 no.1
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• pp.17-25
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• 2007

Recently, the ubiquitous computing environment being able to connect all kinds of computing elements at anytime anywhere becomes widespread in human life. In this paper, we focus on a PC remote control system using cellular phones. Especially, we design and implement an mobile e-mail transmission system using PC remote control technique. By using our remote controller, cellular phone users can login into their own PC, and then send any file to others by e-mail attachment. To show the correct running of our system, real demonstration results are presented. We are sure that by opening our source code to the public our results can play an important role to encourage development of the various mobile remote control functionalities.