• Journal of the Korea Society of Computer and Information
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• v.11 no.1 s.39
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• pp.185-194
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• 2006

The ubiquitous computing environment focuses on recognizing the context and Physical entities, whereas, previous computing environments mainly focused on the conversational interactions between the computer and the user. For this reason, there has been an increase in the research of context aware computing environments. In previous researches , context services are designed using context ontology used in context aware middleware. So, context service cannot change the context ontology in execution time. We propose a hierarchical context ontology management for context aware service to change their ontology in execution time. And we also a resolution model for context conflict which is occurred in inference of context. We have designed a middleware based on this model and implemented the middleware. As the middleware is implemented on the OSGi framework, it can cause interoperability among devices such as computers, PDAs, home appliances and sensors. It can also support the development and operation of context aware services, which are required in the ubiquitous computing environment.

• Journal of Information Processing Systems
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• v.7 no.2
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• pp.287-298
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• 2011

Efficient service description and modeling methodologies are essential for dynamic service composition to provide autonomous services for users in ubiquitous computing environments. In our previous research, we proposed a 'u-service' ontology which is an abstract and structured concept for device operations in ubiquitous environments. One of the problems that we faced during the design process was that there are not enough standards to analyze the effectiveness of a u-service ontology. In this paper, we propose a quality evaluation model to facilitate the design process of a uservice ontology. We extract modeling goals and evaluation indicators based on the uservice description specification. We also present quality metrics to quantify each of the design properties. The experiment result of the proposed quality model shows that we can use it to analyze the design of u-service ontology from various angles. Also, it shows that the model can provide a guideline, and offer appropriate recommendations for improvements.

• Proceedings of the Korea Contents Association Conference
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• 2005.11a
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• pp.275-278
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• 2005

We describe the Ubiquitous Healthcare Service(UHS) architecture, a new service-provision architecture, covering the basic concept, component and their roles and the service-provision mechanism. A UHS provides services in two phases, a service composition phase in which Healthcare Service Elements (HSEs) are combined on the basis of Healthcare Service Agents (HSAs), and a Healthcare Service emergence phase in which a new HSA is obtained on the basis of the history usage of HSEs and HSAs. A UHS can handle various types of HSEs, representing web services, resources about healthcare domain. The establishment of UHS technologies on networks will provide various services within ubiquitous-computing environments.

• Journal of KIISE:Software and Applications
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• v.37 no.3
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• pp.185-193
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• 2010

With the emergence of ubiquitous computing era, various models for providing personalized service have been proposed, and, especially, several recommendation service schemes have been proposed to give tailored services to users proactively. However, the previous recommendation service schemes utilize a wide range of data without and filtering and consider the limited context-aware information to predict user preferences so that they are not adequate to provide personalized service to users. In this paper, we propose an adaptive recommendation service scheme which proactively provides suitable services based on the current context. We use accumulated interaction contexts (IC) between users and devices for predicting the user's preferences and recommend adaptive service based on the current context by utilizing clustering and collaborative filtering. The clustering algorithm improves efficiency of the recommendation service by focusing and analyzing the data that is collected from the locations nearby the users. Collaborative filtering guarantees an accurate recommendation, even when the data is insufficient. Finally, we evaluate the performance and the reliability of the proposed scheme by simulations.

• The KIPS Transactions:PartC
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• v.14C no.6
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• pp.481-492
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• 2007

The ubiquitous environment allows users to communicate with others and to have access to computing service any time, any place. Multipoint VoIP is expected to be one of the loading applications in this environment. The paper compares various conference models for efficient VoIP service in ubiquitous environment and shows why the endpoint mixing model performs effectively in this environment. However, the endpoint mixing model has its own drawbacks as well and we propose solutions to solve the problems.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.2
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• pp.1-9
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• 2010

The increasing popularity of mobile devices, such as cellular phones, smart phones, and PDAs, has fostered the need to recommend more effective information in ubiquitous environments. We propose the recommendation method for mobile contents service using contexts and prefetching in ubiquitous environment. The proposed method enables to find some relevant information to specific user's contexts and computing system contexts. The prefetching has been applied to recommend to user more effectively. Our proposed method makes more effective information recommendation. The proposed method is conceptually comprised of three main tasks. The first task is to build a prefetching zone based on user's current contexts. The second task is to extract candidate information for each user's contexts. The final task is prefetch the information considering mobile device's resource. We describe a new recommendation.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.04a
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• pp.551-554
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• 2004

정보기술과 무선 인터넷의 발전으로 인하여 차세대 정보기술의 패러다임이 점차 유비쿼터스 컴퓨팅 (ubiquitous computing)으로 바뀌고 있다. 최근에는 기존의 상거래 서비스와 기타 서비스 분야에서도 유비쿼터스 기술을 접목하여 유비쿼터스 커머스 (U-Commerce), 또는 유비쿼터스 서비스 (U-Service) 형태로 변화를 시도하고 있다. 그 결과 대부분의 기존 유비쿼터스 관련 연구자는 유비쿼터스 서비스를 위한 네트워크 환경이나 플랫폼 중심으로 많은 연구를 진행하였다 따라서 본 연구에서는 첫째, 유비쿼터스에 대한 기존 연구를 요약 하므로써, 향후 이와 관련된 연구를 시도하는 연구자들에게 유비쿼터스에 대한 통합적인 시각을 제시하고자 한다. 둘째, 유비쿼터스 연구 동향과 미래 발전 방향에 대한 통합 프레임워크를 제시하여 국내외 기술 발전의 현 상태를 점검하고 더 나아가 미래 발전방향에 대한 통합적인 시각을 갖고자 한다.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.174-176
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• 2006

Sensor network supports data delivery from Physical world to cyber space. Sensors get physical events then wireless network transfers sensor data to service server. We use sensor network technology to light control system for intelligent building. In ubiquitous computing environment. wireless sensor network is basic tool for intelligent service. In this paper, we propose intelligent building light control system based on wireless sensor network. It is implemented using previous light control product, can be adopted to present building light system.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.233-234
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• 2004

The study for ubiquitous computing infra is proceeding actively, it make possible to use service and access network anywhere, anytime because of wire/wireless communication technology and progress of hardware. Domestically, study for the network mobility support technology which is the key technology for future ubiquitous computing realization have progressed, but that is Insufficient. Especially, there is no study for independent mobility support study about railway wireless network. So, this study propose network mobility management technology for mobile network infra in railway and proper network model in train.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1562-1564
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• 2005

The study for ubiquitous computing infra is proceeding actively, it make possible to use service and access network anywhere, anytime because of wire/wireless communication technology and progress of hardware. Domestically, study for the network mobility support technology which is the key technology for future ubiquitous computing realization have progressed, but that is insufficient. Especially, there is no study for independent mobility support study about railway wireless network. So, this study propose network mobility management technology for mobile network infra in railway and proper network model in train.