• Journal of the Korean Society for Precision Engineering
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• v.24 no.6
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• pp.7-14
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• 2007

• The KIPS Transactions:PartA
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• v.12A no.4 s.94
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• pp.273-280
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• 2005

The mobility or highly interconnected and communicating devices and users has implications for the QoS in a ubiquitous computing environment. Therefore, it is important for location aware systems to detect location of mobile object correctly and Provide high quality services in ubiquitous environment. However, it is not easy that location aware systems offer highly reliable QoS to users because process strategies of location aware systems are limited by the capability according to the applied detection target objects. In this paper, we design an autonomic architecture which analyzes the location aware system condition and autonomously chooses the best appropriate process strategy. We also have simulated the Proposed architecture in order to verify its performance. The test results show us that the architecture using self-optimizing mechanism provides higher QoS to users in variable bandwidth.

• ETRI Journal
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• v.29 no.2
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• pp.169-178
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• 2007

With the advent of ubiquitous computing environments, it has become increasingly important for applications to take full advantage of contextual information, such as the user's location, to offer greater services to the user without any explicit requests. In this paper, we propose context-aware active services based on context-aware middleware for URC systems (CAMUS). The CAMUS is a middleware that provides context-aware applications with a development and execution methodology. Accordingly, the applications based on CAMUS respond in a timely fashion to contextual information. This paper presents the system architecture of CAMUS and illustrates the content recommendation and control service agents with the properties, operations, and tasks for context-aware active services. To evaluate CAMUS, we apply the proposed active services to a TV application domain. We implement and experiment with a TV content recommendation service agent, a control service agent, and TV tasks based on CAMUS. The implemented content recommendation service agent divides the user's preferences into common and specific models to apply other recommendations and applications easily, including the TV content recommendations.

• Journal of the Korea Society of Computer and Information
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• v.12 no.6
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• pp.115-121
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• 2007

Recently, Location Based Service including tracking and way-finding services has been activated rapidly in the ubiquitous computing environment. According as the ubiquitous computing environment is developed, various types of sensor to acquire various data including location of the moving object are used widely, and acquired sensor data becomes abundant. However, the existing location management system based on a single location sensor is difficult to support LBS efficiently in the ubiquitous computing environment. In this paper, therefore, we propose the location management system in the ubiquitous computing environment that can manage the location data and the various sensor data efficiently. In addition, the location management system adopts the core technology for efficiently storing and transferring a large-volume of various data such as location data and for efficiently processing the various requests from a variety of servers and sensors. Especially, our architecture that is presented in this paper can support context-aware services and autonomous services efficiently in the ubiquitous computing environment.

• Journal of Internet Computing and Services
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• v.9 no.2
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• pp.131-138
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• 2008

The goal of our research is to develop a smart location-based self guided lour assistant as a context-aware real world application. As a context-aware tourist guide application, we hove been developing a PDA-based location-aware tourist guide application for the old palace Deoksugung in the center of Seoul. It will guide visitors to the palace with information about: current location, attractions nearby, and details about specific buildings. Rich multimedia support has been incorporated into the system to provide extra features to enhance the self-guided tour.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.286-288
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• 2005

If we are to realize the everyday benefits promised by pervasive computing and context-aware applications, we must first develop the infrastructure to provide contextual location and orientation information through pervasive computing elements. We have implement indoor positioning system to supply orientation information. We have used ultrasound in indoor positioning system for distance and orientation measurements, then propose a set of methods to calculate orientation from an array of well placed ultrasonic sensors operating in the indoor positioning system. We have design and implement a indoor positioning system using a combination of hardware and software and demonstrate end-to-end functionality of the system.

• Journal of Communications and Networks
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• v.7 no.2
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• pp.207-221
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• 2005

The proliferation of wireless local area networks (WLANs) offering high data rate in hot spot area have spurred the demand for possible WLANs and third-generation (3G) cellular network integration solutions as the initiative step towards 4G systems. This paper provides a novel architecture for seamless location-aware integration of WLANs into 3G cellular networks and also an analysis for the efficient handover techniques. We introduce location as a key context in secure roaming mechanism for context-aware interworking in 4G systems. The fast secure roaming with location-aware authentication is implemented at an entity called location-aware service (LAS) broker that utilizes the concepts of direction of user and pre-warming zone. The location-ware interworking architecture supports seamless roaming services among heterogeneous wireless networks including WLANs, wireless metropolitan area networks (WMANs), and 3G cellular networks. This paper also includes a description of procedures needed to implement efficient mobility and location management. We show how the LAS broker with pre-warming and context transfer can obtain significant lower latency in the vertical handover.

• IE interfaces
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• v.21 no.1
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• pp.65-74
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• 2008

In the future, the ubiquitous computing environment will provide users with context-aware services, intelligently interacting with omnipresent resources and surrounding environments at any location and time. Therefore, the ubiquitous computing environment requires context-aware applications in order to gather and analyze context information in various situations. However, existing context-aware applications have mainly focused on providing services and adapting themselves to users based on user related contexts. But this environment requires not only user related contexts but also Quality-of-Service (QoS) related contexts. In this paper we propose a frame-work for supporting user-oriented QoS in ubiquitous environments. The proposed approach adopts a semantic ontology and a neural network algorithm in order to reason about explicit and uncertain contexts. We also show the possibility of applying the framework to real environments such as collaborative engineering service, automobile maintenance service and ubiquitous home service.

• Architectural research
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• v.12 no.2
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• pp.15-22
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• 2010

Our prediction model is based on the development of "Semantic Location Model." It embodies geometrical and topological information which can increase the efficiency in prediction and make it easy to manipulate the prediction model. Data mining is being implemented to extract the inhabitant's location patterns generated day by day. As a result, the self-learning system will be able to semantically predict the inhabitant's location in advance. This context-aware system brings about the key component of the ubiquitous computing environment. First, we explain the semantic location model and data mining methods. Then the location prediction model for the ubiquitous computing system is described in details. Finally, the prototype system is introduced to demonstrate and evaluate our prediction model.

• Journal of KIISE:Databases
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• v.31 no.5
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• pp.505-515
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• 2004

One of the most important issue in location-aware computing is tracking moving objects efficiently. To this end, an efficient protocol which updates location information in a location server is highly needed. In fact, the performance of a location update strategy highly depends on the assumed mobility pattern. In most existing works, however, the mobility issue has been disregarded and too simplified as linear function of time. In this paper, we propose a new mobility model, called state-based mobility model (SMM) to provide more generalized framework for both describing the mobility and updating location information of complexly moving objects. We also introduce the state-based location update protocol (SLUP) based on this mobility model. Using experimental comparison, we illustrate that the proposed technique is many times better in reducing location update cost and the communication bandwidth consumption.