• The KIPS Transactions:PartC
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• v.16C no.6
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• pp.691-698
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• 2009

A mobile communication device is a small size of portable computer which provides communication service, such as smart phone and PDA. Currently, one of the biggest barriers in developing the mobile communication device is security issue. Even though there are excellent security functions which can remove the security issues, there is a problem that the mobile communication device can not be loaded with all the functions because it has low storage, poor computational power, and inconvenient user interface, compared to the desktop personal computer. This paper proposes a context-aware security reconfiguration scheme for effective security management of the mobile communication device. The scheme can provide the mobile communication device with the optimized security service which is most adapted to its current security context. Through the prototype implementation and the experiments of the proposed scheme, we have confirmed that the proposed scheme is excellent in terms of computing resource efficiency and usability, without degrading security level.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.256-259
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• 2004

Recently, Location-based services(LBS) allow consumers to receive services based on their geographic location data. Users want to take services based location information with portable devices. And Point of Interest(POI) information's usage is increasing with mobile device's development and user's interest. And this paper shows that we connect the multimedia POI database(DB), provide the multimedia services through the portable devices and search POI using location and direction information. The multimedia POI is consisted of sound, image, moving image and animation with location information. When we search POI, we find POI in DB using the area zone and direction information.[l]

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.6
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• pp.41-50
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• 2011

This article is concerned with the technology to provide car driver the car's status which are composed of car trouble code in car engine and many sensors. In addition, it installs vehicle diagnostic programs on wireless communication's portable device, for example, Smart phone, PDA, PMP, UMPC. As a result, this is to provide car manager with many information of car sensors when we go to car maintenance. it can monitor relevant information on vehicle by portable device in real time, alert drivers with specific messages and also enable them to address abnormalities immediately. Moreover, the technology could help the drivers who perhaps don't know very well about their vehicles to drive safely and economically as well; the reason is because the whole system is composed of just Vehicle-information collecting device and personal wireless communication's portables and transfers the relating data to server computers through wireless network in order to handle information on vehicles. This technology make us monitor vehicle's running, failure and disorder by using wireless communication's portable device. Finally, this study system is composed of a lot of application to display us the car's status which get car's inner sensor information while driving a car.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.619-622
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• 2007

PDA provides an opportunity for users to study anytime and anywhere because it is portable and convenient thanks to its relatively small size. However, users may face difficulties to fully recognize the characters provided through lecture videos, due to its low resolution and small scaled screen. This thesis proposes a system of remote lecture in which the size of videos can be adjusted and transmitted on the basis of contents necessary for study, using detection of region-of-interest(ROI) image, and a method of image scaling in a bid to solve such a problem of PDAs. The experiment on 802.11b wireless network shows that the proposed system is able to provide more optimized lecture videos than in existing method.

• Korean Journal of Materials Research
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• v.15 no.9
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• pp.613-619
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• 2005

The ever increasing popularity and acceptance in the market place of portable systems, such as cell phones, PDA, notebook PC, etc., are fueling effects in further miniaturizing and lowering power consumption in these systems. The dynamic power consumption due to the CPU activities and the static power consumption due to leakage currents are two major sources of power consumption. Smaller devices and a lower de voltage lead to reducing the power requirement, while better insulation and isolation of devices lead to reducing leakage currents. All these can be harnessed in the SOI (silicon-on-insulator) technology. In this study, the key aspects of the SOI technology, mainly device electrical properties and device processing steps, are briefly reviewed. The interesting materials issues, such as SOI structure formation and SOI wafer fabrication methods, are then surveyed. In particular, the recent technological innovations in two major SOI wafer fabrication methods, namely wafer bonding and SIMOX, are explored and compared in depth. The results of the study are nixed in that, although the quality of the SOI structures has shown great improvements, the processing steps are still found to be too complex. Between the two methods, no clear winner has yet emerged in terms of the product quality and cost considerations.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.51.2-51.2
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• 2010

Efficient and durable electrical energy storage is one of the major factors limiting the wide-spread adoption of renewable energy. Since lithium-ion batteries (LIBs) were first commercialized in the early 1990s, LIBs have emerged as an important energy storage device for portable electronics. LIBs are very desirable because of their high energy storage per volume and per mass. However, LIBs with high energy and power as well as higher stability are needed for their use in a variety of energy storage applications such as MEMS devices, PDA, plug-in hybrids, all-electric vehicles and large scale utility systems. In this talk, I will discuss present energy perspective, especially energy storage and its role in renewable energy. After that I will discuss the recent advances in nanostructured materials and interface engineering that have led to the achievement of improved Li-ion batteries. Finally I will talk aboutcritical issues that need to be addressed to obtain further improvements in Li-ion batteries.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.114.6-114
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• 2001

According to expansion of wireless communication system and mobile device, interest has been growing in personal navigation system integrated with wireless system. In portable consumer electronics, such as cellular phones, GPS and PDA, one of major design factors is the power consumption. Solutions of reducing the power dissipation are low voltage, low system clock power management and so on. This paper develops a GPS receiver based on the advanced power management algorithm that achieves very low average power consumption. Both RF and DSP chips are powered down and reactivated only when the position fixing is required. In order to run, the developed includes the RTC calibration function and the fast reacquisition function using XMC (eXtended Multiple Correlator) ...

• Journal of IKEEE
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• v.9 no.2 s.17
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• pp.170-178
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• 2005

The video data corrupted by the transmission error due to packet loss induce error propagation in decoded video data, and cause poor video quality. To remedy these corrupted video data, there have been introduced two types of error concealment techniques: spatial or temporal error concealment algorithm. Computational overhead by using spatial error concealment algorithm is a serious disadvantage in mobile video data streaming environment. In this paper, we propose hybrid type error concealment technique recovering video quality of mobile device using MPEG-4 video streaming on error-prone wireless network. Our algorithm is implemented in MPEG-4 decoder. The algorithm adopts Intel Wireless MMX technology to provide high performance of portable embedded multimedia mobile device. It is proven that the proposed algorithm shows expected performance for a mobile streaming system(PDA) on IP channels. Our approach showed better processing speed and better video quality comparing with traditional error concealment algorithm.

• Journal of Broadcast Engineering
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• v.12 no.2
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• pp.137-147
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• 2007

Projection-based augmented reality (AR) system refers to the system that accurately project high quality virtual information at the user-specified area by using the projector. Most of projection-based AR systems use the display device to support high quality and wide screen for increasing the user-immersion. Furthermore, they are implemented on the desktop environment due to the computational complexity. However, these projection-based AR systems are not suited as a mobile system and thus it may be inconvenient in the user point of view. Fortunately, Miniaturization of projectors and improved capacity of the mobile processor allowed the mobile AR system to be convenient. The limitation of established mobile AR system is that it uses small display screen which does not support high-resolutions and thus it may reduce the user-immersion into the system. In this paper, we propose portable projection-based display system, which overcomes the limitations of both projection-based and mobile-based AR systems. We have conducted the user evaluation to verify the effectiveness and the utmost capacity of the system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12B
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• pp.831-837
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• 2005

Personal general purpose computer(PC) has been evolved from desktop to portable mobile device such as tablet PC and PDA. Technology innovation on semiconductor have made it possible to package a reasonably Powerful Processor and memory subsystem with advanced input/output devices. At last these subsystems are miniaturized into wearable system. Wearable computer has recently gained attention as the post PC in the ubiquitous environment. Wearable computing becomes more and more feasible and receives growing attention throughout industry and the consumer marketplaces. This paper proposed and developed WPS that has multimedia features and network features as a wearable embedded platform. We explain the form, overall architecture, functions and user applications of this WPS. This paper also discusses the form of next generation computer platform with intuitive user interfaces and well designed applications in the future.