• Journal of the Korea Society of Computer and Information
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• v.14 no.2
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• pp.103-110
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• 2009

We are witnessing rapid increase of the number of wireless devices available today such as cell phones, PDAs, Wibro enabled devices. Because of the inherent limitation of the bandwidth available for wireless channels, broadcast systems have attracted the attention of the research community. The main problem in this area is to develop an efficient broadcast program. In this paper, we propose a dynamic broadcast method that overcomes the limitations of static broadcast programs. It optimizes the scheduling based on the probabilistic model of user requests. We show that dynamic broadcast system can indeed improve the quality of service using user requests. This paper extends our previous work in [1] to include more thorough explanation of the proposed methodology and diverse performance evaluation models.

• Journal of Convergence Society for SMB
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• v.3 no.2
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• pp.27-32
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• 2013

Wireless Body Area Networks (WBAN) have been made possible by the emergence of small and lightweight wireless systems such as Bluetooth, enabled devices and PDAs. Antennas are an essential part of any WBAN system and due to various technical requirements and physical constraints, careful consideration of their design and deployment is needed. This paper is proposing on the design of wearable antenna as parts of clothing to serve communications functions, such as tracking and navigation in health care applications. The substrates of the wearable antennas will be made from textile materials and since it is wearable, it should have a small size, be light weight, low maintenance, and unobtrusive. This proposed paper will also investigate the influence of different parameters for wearable antenna including types of textile/substrate to ensure that the antenna design satisfies WBAN requirements. The characteristics and behavior of the antenna need to adhere to specifications set by wireless standards and system technology requirements. This means that the transmitting and receiving frequency bands of the various units need to be chosen accordingly. Since there are restrictions on the level of power to which the human body can be exposed to, the antenna as well as other RF system components must be designed to meet these restrictions. Antenna gain, which directly affects power transmitted, is a critical parameter in ensuring power levels fall within the safety guidelines and so will be of primary importance in the design. The electromagnetic interaction between WBAN antennas and devices and the human body will also be explored.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.69-72
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• 2008

In the paper, embedded system that manage, control the status of vehicle through internet and mobile instruments are designed. The network is composed of the distributed control system using CAN communication, where communication is possible with two lines, and the bluetooth, where wireless communication is possible. We also designed the Embedded system to make up the web server only for the vehicle, made it possible to catch hold of the conditions of the vehicle and control the vehicle through internet by interfacing the destributed controller. We also made such a Web Server possible th be monitored and controlled by the mobile instruments such as PDA, mobile phones.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.467-470
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• 2009

본 논문에서는 유비쿼터스 기반 인프라를 이용한 실시간 유괴방지 시스템을 구축하였다. 급속한 사회 발전과 더불어 강력사건이 증가되고 있으며 그중에서 어린이 유괴 범죄 같이 질적으로 흉악한 범죄가 해마다 증가되고 있는 실정이다. 이러한 유괴 범죄를 예방하기 위하여 현재 GPS(Global Positioning System)을 이용한 위치인식 기술 및 이동통신 기지국을 이용한 위치인식 기술이 사용되고 있다. 단순히 위치인식 기술은 위험상황이 발생하였을 때, 상황을 정확히 인지하기 어려워 유괴된 어린이 44%가 1시간 이내 사망하고 74%가 3시간 이내 사망 한다는 통계를 감안하면 기존 시스템은 어린이 생명 보호 능력에 한계가 있다. 본 연구에서는 유비쿼터스 도시 기반 인프라를 구축하여 WPAN(Wireless Personal Area Network)환경에서 RF만으로 거리 측정이 가능한 IEEE 802.15.4a의 ISM Band CSS(Chirp Spread Spectrum)방식을 이용하여 보다 저 전력으로 정확한 위치정보 시스템을 적용하였다. 이에 CSS방식을 통하여 얻은 위치정보를 지능형 CCTV와 융합하여 CCTV가 단말기 위치로 자동 초점하는 시스템을 구성하였다. 도시통합운영센터에서 상황을 정확히 인지하고 신속하게 출동할 수 있도록 단말기 위치를 지속적으로 요원의 PDA 및 핸드폰으로 통보하고 현장 주변의 미디어 보드 표시와 음성 경고로 경찰의 적절한 대응 및 주변의 도움을 받을 수 있는 시스템을 구성하였다.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.1185-1188
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• 2005

Recently, ubiquitous computing and sensor networks are making a rapid development. These technology can enable a new way of biomedical signal processing and healthcare. that is, they can improve care giving by a more flexible acquisition of relevant vital sign data, and by providing more convenience for patients. In this paper, we realize the biomedical sensor networks by applying IEEE 802.15.4/Zigbee networks to some various biomedical sensing unit. For address this, we developed minimized zigbee module and set-up procedure using PDA. The main advantages that we achieve are interference-free operation of different body sensor networks in the vicinity, as well as intuitive usage by the nontechnical personnel.

• The Journal of Korean Association of Computer Education
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• v.5 no.3
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• pp.19-25
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• 2002

Bluetooth, in radio network environment, is a small local radio communication that is available with low expense and little power use. It is specified for the wireless connect in a small area between Network Excess Point, portable devices such as mobile phones. PDAs and portable PCs, and other per peripheral equipment. Bluetooth is consisted of a master and a piconet having seven slaves in a maximum and finally has a scatternet gathering lot of piconet. The thesis tries to design the most effective structure of a scatternet by the number of nodes and the type of scatternet such as linear and ring for its mechanism. then the performance evaluation is realized through the Bluehoc simulator based on the NS. Finally the most appropriate radio network environment is made by the comparison and analysis of the characteristics of liner and ring scatternets.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.239-242
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• 2000

Bluetooth is generally called as wireless technology$.$standard$.$product for communicating in a short distance which is in order to implement both-sides short distance telecommunications at low price without complicated electric wires. SIC is the cooperation group which is composed of telecommunications, computer, eminent network firms for technological development and building the market. It actually made a scheme for standardization. SIG, Ericsson takes a main role in SIG. is composed of about 1,800 member companies and the members are increasing continuously. It was announced Bluetooth version 1.0 from SIG August 1999 and the products such as software development kits, core components will come out soon later. In this paper, Bluetooth technological development and the present state of standardization are investigated and analyzed.

• International Journal of Costume and Fashion
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• v.4 no.2
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• pp.45-55
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• 2004

Rapid informatization and technology advance in the 21st century has invited a new paradigm and changed many things in human life pattern. The impact of mobility seen in this digital nomadism has brought about, when it comes to clothing, a change in its unique meaning, that is, the graftage of high technology onto present nomad's life style who live moving around all the time due to the expansion of mobile environment. As the fruits of this expansion of mobile environment and technology advance in wireless telecommunication, easy-to-carry smaller sized devices such as cell phones, PDA, and MP3 players represent the present times, while the future would be an 'era of wearing' in which kinds of electronic devices and systems are integrated into clothing. Thus in this study, concept of wearable computer seen in the 21st century's digital nomadism was reviewed, and figurativeness and anesthetic value of wearable computer were discussed in association with the change in high style image resulted from technology advance and change of life style. By drawing a justice from which, value of future fashion was also prospected.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1B
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• pp.9-18
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• 2006

Advances in wireless network are enabling the development of ubiquitous multimedia services. These multimedia services need efficient platforms to comply with the requirements of mobile computing. We introduce an adaptive service platform based on mobile agent and grid systems while specifying the challenges of ubiquitous multimedia services and focusing on frequent disconnections and scarce resources. We applied our platform to framework RtoA (Ready-to-Attend) which supports mobile users to access compute-intensive multimedia service, specifically, mobile education and video conferencing. RtoA includes hand-off, speaker and listener service which enable people to attend a conference or a class with satisfying quality of multimedia service. ns-2 based simulation verifies that our scheme is an efficient way to reduce energy consumption of mobile devices and to improve the response time of mobile applications.

• Journal of Information Technology Services
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• v.13 no.3
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• pp.309-321
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• 2014

Recently, due to the advent of ubiquitous computing and the spread of intelligent portable device such as smart phone, iPad and PDA has been amplified, a variety of services and the amount of information has also increased fastly. It is becoming a part of our common life style that the demands for enjoying the wireless internet are increasing anytime or anyplace without any restriction of time and place. And also, the demands for e-commerce and many different items on e-commerce and interesting of associated items are increasing. Existing collaborative filtering (CF), explicit method, can not only reflect exact attributes of item, but also still has the problem of sparsity and scalability, though it has been practically used to improve these defects. In this paper, using a implicit method without onerous question and answer to the users, not used user's profile for rating to reduce customers' searching effort to find out the items with high purchasability, it is necessary for us to analyse the segmentation of customer and item based on customer data and purchase history data, which is able to reflect the attributes of the item in order to improve the accuracy of recommendation. We propose the method of recommendation system using association rule and weighted preference so as to consider many different items on e-commerce and to refect the profit/weight/importance of attributed of a item. To verify improved performance of proposing system, we make experiments with dataset collected in a cosmetic internet shopping mall.