• Journal of Powder Materials
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• v.25 no.3
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• pp.263-272
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• 2018

Recent developments in the field of energy harvesting technology that convert ambient energy resources into electricity enable the use of self-powered energy systems in wearable and portable electronic devices without the need for additional external power sources. In particular, piezoelectric-effect-based flexible energy harvesters have drawn much attention because they can guarantee power generation from ubiquitous mechanical and vibrational movements. In response to demand for sustainable, permanent, and remote use of real-life personal electronics, many research groups have investigated flexible piezoelectric energy harvesters (f-PEHs) that employ nanoscaled piezoelectric materials such as nanowires, nanoparticles, nanofibers, and nanotubes. In those attempts, they have proven the feasibility of energy harvesting from tiny periodic mechanical deformations and energy utilization of f-PEH in commercial electronic devices. This review paper provides a brief overview of f-PEH devices based on piezoelectric nanomaterials and summarizes the development history, output performance, and applications.

• Journal of information and communication convergence engineering
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• v.8 no.1
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• pp.77-82
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• 2010

Residential network is the hybrid technology of wireless, Ethernet, Bluetooth and RF to the internet via broadband connection at home to facilitate the convenient, safe and pleasant daily lives of home user with various home network services regardless of device, time and place. For ubiquitous development more devices will be wireless and most of them will be roaming. Since these roaming devices carry private information of daily life of residential users, the interaction among the roaming devices of residential network must be secure. This paper presents to secure registration of roaming devices using IP Security (IPSec) Protocol Suite without the need to trust foreign agents.

• International Journal of Contents
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• v.9 no.1
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• pp.18-25
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• 2013

Recently, augmented reality has been proved immensely useful on a day to day basis when tied with location-based technology. In this paper, we present a new method for displaying augmented reality contents on mobile devices. We add 3D models on the view of the camera and use location-based services, motion sensors to calculate the transformation of models. Instead of remaining at a fixed position on camera view while moving around a 3D model, the model rotates on display in the opposite direction that the user is walking. We also design client as a ubiquitous client to reduce constraints on disk space and memory capacity on mobile devices. Implementation results show effective use in creating GPS-based 3D view augmented reality contents for Smart Mobile Devices.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.4
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• pp.569-577
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• 2009

Mobile information retrieval is an evolving branch of information retrieval that is centered on mobile and ubiquitous environments. In general, mobile devices are characterized by lightweight, low power, small memory, small display, limited input/output, low bandwidth, and so on. Some of these characteristics make it impossible to apply general information retrieval to mobile environments without any modification. In order to relieve this problem, we design and implement an information retrieval system for mobile devices like wireless phones, PDA and handheld devices. We use document summarization techniques to alleviate the limitation of small display and user profiles to retrieve the most proper documents for each individual user for personalized search. Futhermore we use meta-search to lighten some burdens visiting several portal sites. In this paper, we have implemented and demonstrated the proposed mobile information retrieval system on the domain of travel and received good evaluation from users subjectively.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.7
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• pp.3413-3430
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• 2017

With the fast increasing popularity of mobile services, ubiquitous mobile devices with enhanced sensing capabilities collect and share local information towards a common goal. The recent Mobile Crowd Sensing (MCS) paradigm enables a broad range of mobile applications and undoubtedly revolutionizes many sectors of our life. A critical challenge for the MCS paradigm is to induce mobile devices to be workers providing sensing services. In this study, we examine the problem of sensing task assignment to maximize the overall performance in MCS system while ensuring reciprocal advantages among mobile devices. Based on the overlapping coalition game model, we propose a novel workload determination scheme for each individual device. The proposed scheme can effectively decompose the complex optimization problem and obtains an effective solution using the interactive learning process. Finally, we have conducted extensive simulations, and the results demonstrate that the proposed scheme achieves a fair tradeoff solution between the MCS performance and the profit of individual devices.

• Journal of Ubiquitous Convergence Technology
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• v.1 no.1
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• pp.42-46
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• 2007

In this paper, we proposed an efficient short address allocation mechanism for WiBEEM devices using NAA(Next Address Available) algorithm. The proposed addressing mechanism is based upon the NAA information that is delivered over the beacons every time it is transmitted at the beginning of each super-frame. The NAA-based addressing mechanism is not a systematic way of allocating short addresses to newly joining devices and thus tree-routing cannot be supported. However, it has great advantages when U-City core services including U-Parking Lot System or ATIS(Advanced Traveler Information System) services that require high-speed mobility are considered. Moreover, the proposed addressing mechanism can provide significant expandability of the wireless network to various applications and fast device discovery.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.267-276
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• 2009

Nowadays, numerous of valuable internet services are available not only for personal computer but also for mobile appliances in wireless network environment. Therefore, as the amount of contents is increased for those services, the storage limitation on mobile devices has became a significant issue. In this paper, we present a new block-level storage network protocol, iATA (Internet Advanced Technology Attachment) as a solution to the above problem. iATA is designed to transport ATA block-level data and command over the ubiquitous TCP/IP network. With iATA, a mobile appliance is able to access and control the ATA storage devices natively through network from anywhere and at anytime as if the storage devices is attached locally. We describe the concepts, design and diverse consideration of iATA protocol. Based on the benchmark experiments and application exploitation, we strongly believe that iATA as a light-weight protocol is efficient and cost-effective to be used as a storage network protocol on a resource limited device that utilizes common-off-the-shelf storage hardware and existing IP infrastructure.

• Korean Journal of Health Education and Promotion
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• v.25 no.1
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• pp.13-23
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• 2008

Objective: The current study was to test if the developed sphygmomanometer was working well and blood pressure information could be collected and monitored systematically through the internet. We tested if the sphygmomanometer and services for blood pressure controlled high blood pressure significantly and the ubiquitous monitoring could be used further. Methods: Kyungwon University, KT Co., Gil Medical Center, LIG Nex1 Co., and Sujeong Health Center conducted an ubiquitous high blood control project in Sujeong-gu, Sungnam, Korea from Mar. 5 to May 16. We developed and applied sphygmomanometer. We distributed the devices to 27 high blood pressure patients. The blood pressures of the residents were monitored through the internet when they measured blood pressures in their homes. A nurse monitored and consulted their blood pressures in the monitoring center in Kyungwon University during the demonstration period. The consultant called them and consulted on their blood pressures in few seconds they used the sphygmomanometers. For the significance of change in blood pressure, we tested statistically with Generalized Additive Model(GAM) and Multi-level Analysis. Results: Both GAM and Multi-level Analysis showed that the blood pressures of persons with ubiquitous blood pressure management decreased significantly as time passed. Conclusions: The internet monitoring and services are considered to be promising because most of the participants were satisfied especially because somebody was caring their health. The decrease of blood pressures was significant by GAM and Multi-level Analysis. Thus, we can apply ubiquitous blood pressure management to health promotion projects.

• ETRI Journal
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• v.29 no.3
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• pp.281-291
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• 2007

Wearable computers consisting of various small devices such as smart phones, digital cameras, MP3 players and specialized I/O devices in personal area networks will play an important role in future ubiquitous computing. In this environment, accessing user data is quite complex due to the dynamic and heterogeneous characteristics of the underlying networks. Moreover, since the amount of user data increases rapidly, automatic data backup management is also critical. To overcome these challenges, several studies have been conducted including our previously proposed file service system, PosCFS, which could be adapted to the requirements with a virtualization technique allowing per-user global namespace for managing and accessing data stored on physical storage spaces detected in PAN. In this paper, we present a smart file service framework, PosCFS+ which is an improved and extended version of our previous work. Performance improvement is made possible by redesigning the metadata management scheme based on database and keywords rather than ontology. In addition, the automatic data replication management is newly designed based on the OSD protocol.

• Proceedings of the Korea Contents Association Conference
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• 2006.05a
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• pp.136-139
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• 2006

In this paper, We are proposed the real-time monitor and control mechanism for intelligent robot called URC(Ubiquitous Robotic Companion). URC are intelligent robots designed as to interact with external digital device that can communicate through wire or wireless by integration the network and information technology into traditional robot. In this paper, we implemented the result of this study into the target robot called ISSAC4 and proved its practical worth. We designed it as be able to control on remote by such web browser as anywhere and anytime that show a status information for several controllers, devices, actuators and sensors of robot and guarantee a continuity of real-time image transferring by Client-Pull method and moving control of robot.