• Journal of Korea Multimedia Society
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• v.10 no.6
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• pp.799-806
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• 2007

The prototypical smart environment to support the context-aware interactions between user and ubiquitous campus environment based on multi-agent system paradigm is proposed in this paper. In this model, the dynamic Bayesian is investigated to solicit and organize agents to produce information and presentation assembly process in order to allocate the resources for an unseen task across multiple services in a dynamic environment. The user model is used to manage varying user constraints and user preferences to achieve system's goals.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.8
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• pp.394-406
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• 2008

Even though context is the most important feature in context-aware systems, the existing requirements engineering cannot support methodology for elicitation and specification of contexts. In this paper, we propose a requirements elicitation method and a requirements specification method for context-aware systems. Our requirements elicitation method is a 6-stepped, incremental, and iterative process. At the beginning steps in the process, we identify the requirements for business logic. Afterwards, we gather the requirements for context logic, model contexts, and identify subsystems. For requirements specification, we suggest a context-aware use case diagram, a context diagram for context modeling, and a context-type-use-case-dependency diagram for the traceability of use cases on the change of context types. We also introduce a case study that we apply our approaches to a real system, and a qualitative evaluation of our approaches. Our study will help stakeholders to efficiently elicit requirements for context-aware systems and to specify them clearly.

• Journal of Intelligence and Information Systems
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• v.13 no.2
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• pp.27-41
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• 2007

Nowadays the context-aware systems have been regarded as a promising opportunity to create differentiated e-marketplaces. Context-aware system aims to provide personalized services by understanding the user's current situation which is automatically acquired from the context data. This aim naturally leads us to a motivation to evaluate to what extent a system is context-aware. Even though lots of endeavors have stated about the level of context-aware system, a structured evaluation has been so far very rare. Hence, the purpose of this paper is to propose a two-phased methodology for assessing context-aware systems. In the first phase, we perform a requisite analysis to discriminate a context-aware system from general or context-based systems. Once an information system is recognized as context-aware system, then level of collaboration, mobility and embeddedness is derived to determine the level of context-aware system in the second phase. To do so, device collaboration diagram (DCD) is proposed to visualize the system architecture. Moreover, readiness and level of system are Jointly considered in the phase to provide a development strategy for each context-aware system development project. To show the feasibility of the idea proposed in this paper, legacy context-aware systems are actually analyzed and evaluated.

• Journal of Service Research and Studies
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• v.4 no.1
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• pp.49-59
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• 2014

Context-aware computing is an emerging paradigm to achieve ubiquitous computing environments by enabling computer systems to understand their situational contexts. A context-aware system uses context to provide relevant information and services to the user depending on the user's task. In this paper, we propose an ontology-based context-aware modeling methodology that transmits low-level contexts acquired by directly accessing various sensors in the physical environments to high-level contexts. With these high-level contexts, context-aware application can provides proactive and intelligent services using ECA (Event-Condition-Action) rules. We implemented a home robot service in smart office environment.

• Journal of Digital Convergence
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• v.10 no.1
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• pp.309-315
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• 2012

The dissemination of smartphones is being spread and supplementary services using smartphones are increasing and various as the Mobile network and device are developing rapidly, so smartphones that enables to provide a wide range of services is expected to receive the most attention. It makes users listen to music anytime, anywhere in real-time, use useful applications, and access to Internet to search for information. The service environment is changing on PC into Mobile due to the change of the circumstance mentioned above. these services are done by using just location information rather than other context, and users have to search services and use them. It is essential to have Context-aware technology for personalization recommendation services and the appropriate representation and definition of Context information for context-aware. Ontology is possible to represent knowledge freely and knowledge can be extended by inferring. In addition, design of the ontology model is needed according to the purposes of utilization. This paper used context-aware technologies to implement a user personalization recommendation service. It also defined the context through OWL modeling for user personalization recommendation service and used inference rules and inference engine for context reasoning.

• KIISE Transactions on Computing Practices
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• v.23 no.11
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• pp.641-649
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• 2017

As Internet of Things devices become pervasive, services improve to better assess the context and to alert other users to deal with emergencies. Such services use Internet of Things devices to detect the context around the user and promptly notify public institutions, hospitals or other parental users in emergencies. Most of these systems analyze an event when the value of the device is unchanged for a period of time or if it detects an abnormal value. However, just monitoring sensor values makes it difficult to accurately understand the context surrounding a user. Also if the device is inactive, it can not identify the context or provide services again. However, understanding the user requirements, services provided through other devices, information sent to other users lets, appropriate actions be taken. This paper, proposes a device search method and system based on a context-aware model that includes user demands. The proposed system analyzes the user's context and demands by using data collected from the internet of things devices. If user devices are inactive, they can recognize other devices by searching for other devices and providing services to users again. Through the proposed method, the user-centric services are provided. This method also analyzes and responds to requirements in various emergencies.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.2
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• pp.114-123
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• 2009

Context-aware systems are reactive computing systems, aware of external context. Considering various sensors and actuators connected, application programming on top of such systems is known to be much more complex than in contentional ones. This paper suggests a formal framework for context-aware systems, by extracting their common properties. That makes a useful birds-eye view for the behaviors of a whole complex system, as a base for a convenient developing environment and systematic analysis. In this framework, reactive-ness is handled by event-condition-action rules and global state-transitions, which are essential in a lot of context-aware applications. In addition, behaviors of each elementary device are modelled with its own state-transitions, and tightly bound to the entire task.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1867-1868
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• 2008

u-City(Ubiquitous city)는 유비쿼터스 컴퓨팅과 정보통신 기술을 기반으로 다양한 u-서비스(Ubiquitous service)를 제공하는 도시이다. u-서비스를 제공하기 위해서는 시스템이 주변 상황(Context)을 인지하여 사용자와 상호작용을 지원하는 상황인지 기술이 중요하다. 최근 상황인지(Context-aware) 기술은 지능형 회의실이나 스마트 홈을 개발하기 위하여 활발히 적용되고 있으나, 광범위한 도시공간을 대상으로 하는 u-서비스를 구현하기 위한 연구는 미진한 실정이다. 본 논문에서는 홍수 모니터링 서비스를 대상으로 온톨로지 기반의 홍수 상황인지 모델을 제안한다. 모델설계를 위해 현재의 홍수 모니터링 시스템을 분석하여 요구사항을 도출하고 홍수 모니터링 시나리오를 작성하였다. 상황 데이터를 분석하고 상황 데이터 수집을 위한 센서(Sensor) 온톨로지(Ontology)를 설계하였다. 다음으로 센서 온톨로지를 통해 수집한 상황 데이터를 추론하여 적절한 서비스를 제공하기 위한 홍수 상황인지 모델을 설계하였다. 제안한 모델은 향후 다양한 u-서비스를 설계하고 구현하는데 응용모델로 활용할 수 있을 것이다.

• Journal of KIISE
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• v.43 no.7
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• pp.763-772
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• 2016

With the spread of smartphones containing multiple on-board sensors, the market for context aware applications have grown. However, due to the limited power capacity of a smartphone, users feel discontented QoS. Additionally, context aware applications require the utilization of many forms of context and sensing information. If context transition has occurred, types of needed sensors must be changed and each sensor modules need to turn on/off. In addition, excessive sensing has been found when the context decision is ambiguous. In this paper, we focus on power consumption associated with the context transition that occurs during indoor/outdoor detection, modeling the activities of the sensor associated with these contexts. And we suggest a freezing algorithm that reduces power consumption in context transition. We experiment with a commercial application that service is indoor/outdoor location tracking, measure power consumption in context transition with and without the utilization of the proposed method. We find that proposed method reduces power consumption about 20% during context transition.

• Convergence Security Journal
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• v.14 no.7
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• pp.75-84
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• 2014

The advancement in ubiquitous healthcare specifically in preventive healthcare can lead to longer life expectancy especially for the elderly patients. To aid in preventing premature loss of lives as well as lengthening life span, this research aims to implement the use of mobile and wireless sensor technology to improve the quality of life and lengthen life expectancy. The threats to privacy and security have received increasing attention as ubiquitous healthcare applications over the Internet become more prevalent, mobile and universal. Therefore, we propose Context-aware Service of U-Healthcare Application based Knowledge using Ontology in secure health information exchange. This research also applies ontology in secure information exchange to support knowledge base, context modeling, and context reasoning by applying the general application areas for ontologies to the domain of context in ubiquitous computing environments. This paper also demonstrates how knowledge base, context technologies, and mobile web services can help enhance the quality of services in preventive ubiquitous healthcare to elderly patients.