• Proceedings of the Korea Inteligent Information System Society Conference
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• 2005.05a
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• pp.131-138
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• 2005

Recommender systems have been widely advocated as a way of coping with the problem of information overload in e-business environment. Most of the existing recommender systems focused on what kind of items to recommend, although when to recommend to the target customer considering their context is an important issue. Even right item might be a spam advertisement or wrong recommendation for the customer if it can not be recommended at the right context. It is particularly important for recommendations where the user's context is changing rapidly, such as in both handheld and ubiquitous computing environment. Therefore, we propose CARS (Context-Aware Recommender System) based on CBR and context-awareness for ubiquitous computing environment. CBR is used to generate a target customer class and proper context. Context-awareness is used to gather suer context information from sensors, networks, device status, user profiles, and other sources. An illustrative case example is suggested to explain the procedure of CARS.

• Journal of the Korean Society of Safety
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• v.23 no.5
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• pp.35-42
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• 2008

There are many efforts toward the development of next generation gas safety management systems to improve the assurance, availability, and efficiency of the extant systems. Among them, the application of ubiquitous technology, such as RFID and USN, to the system is regarded as a promising approach for enabling such an innovation. Recently the ubiquitous technology became much affordable and available than before thanks to the reduced production cost and wide proliferation of the ubiquitous devices. In this paper, we analyze the core requirements for the next generation gas safety management systems based on the ubiquitous technology, and present an architectural design of a middleware to facilitate the realization of the system. We formally define an event model and present how to specify various situations related to gas safety management using the proposed event model.

• Journal of Korea Multimedia Society
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• v.7 no.6
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• pp.767-780
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• 2004

Interaction requires dynamic relationship between objects. In ubiquitous computing environment, interaction between human and the environment is implied. Tactile interaction has so far been less addressed, while tactile sensation should be an important topic in the field of multimedia study. This paper describes development of a novel PVDF (Polyvinylidene Fluoride) dynamic tactile sensor and associated experiments. PVDF dynamic tactile sensors detect touch events applied to the sensor skin by low frequency components of the signal. Rubber skin-covered sensing material was mounted on the bones. Robust performance with low noise was figured out in our robotic experiment. Whereas most conventional sensors are interested in measurement, our dynamic tactile sensor is sensitive to change of state, which could be a key for economic understanding of happenings in the dynamic world. We note that dynamic sensing uses motion as a part of sensing modality We suggest that dynamic sensing be understood in technological terms in the perspective of interactive media and ubiquitous computing.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.274-277
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• 2008

Rekeying is the process of changing the encryption key of an ongoing communication. The main objective is to limit the amount of data encrypted with the same key. The IEEE 802.11 standard defines the Wired Equivalent Privacy, or WEP, encapsulation of 802.11 data frames. MAC at sender encrypts the payload (frame body and CRC) of each 802.11 frame before transmission using RC4 stream cipher. MAC at receiver decrypts and passes data to higher level protocol. WEP uses symmetric key stream cipher (RC4) where same key will be used for data encryption and decryption at the sender and the receiver. WEP is not promising with the advancement of the wireless technology existing today. We propose to use the existing information to define the security attributes. This will eliminate the steps that regenerated keys have to be sent to each other over certain period. The rekeying scheme is according to the number of bytes transmitted. Therefore, even the attacker has recorded the packets, it will be insufficient information and time for the attacker to launch the attacks as the key is not deterministic. We develop a packet simulation software for packet transmission and simulate our propose scheme. From the simulation, our propose scheme will overcome the weak WEP key attack and provide an alternative solution to wireless packet transmission. Besides that, our solution appears to be a software approach where only driver updates are needed for the wireless client and server.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.2
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• pp.27-35
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• 2009

A paradigm of medical industry is changing quickly to u-healthcare according to entry toward an aging society and improvement of quality of life(QoL). The change toward u-healthcare is meaningful since meaning of healthcare is redefined by prevention and management instead of medical service such as diagnosis of disease and treatment. However, the interest about u-healthcare is only concentrated to derivation of new healthcare service, development of medical measurement appliances(Sensors), and integration and standardization of medical information. Therefore, in this paper, the main ai of this study is trying to realize and implement u-healthcare technology through primary philosophies of ubiquitous composition such as Disappear Computing, Invisible Computing, and Calm Computing and development of user-centered technology.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.257-260
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• 2008

We build middleware architecture with J2EE and LiveGraph to process different ubiquitous healthcare application's data and process that data into useful information, which can play a most important role in decision making in ubiquitous Healthcare System. Application developers mostly rely on third party middleware, tools and libraries (i.e., webservers, distributed middleware such as CORBA, etc.) to respond the emerging trends of their target domain. With this middleware we tried to enhance the efficiency of application by decrease their memory uses, data processing and decision making on another web module which is independent of each application. For middleware system, we proposed an algorithm by which we can find some important conclusion about different health status likewise ECG, Accelerometer. etc., which can be used in various data processing and determine the current health status. In this paper we also analyze some different low level and high level middleware technology which were used to build different kind middleware likewise CAMUS, MiLAN and try to find the best solution in the form of middleware for Ubiquitous Healthcare Information System.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06a
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• pp.231-232
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• 2008

• Proceedings of the Korean Information Science Society Conference
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• 2007.06a
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• pp.155-156
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• 2007

• Proceedings of the Korean Information Science Society Conference
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• 2007.06a
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• pp.252-253
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• 2007

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.365-372
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• 2006

We expect u-Education based on ubiquitous information and technology will be the next generation education system. We performed a comparative study of well designed school homepage at H elementary school and the other case of homepage at C elementary school in Seoul. We conclude the former shows better performance and educational achievement under U-Learning environment and we propose a next generation U-Learning system architecture.