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    <article-meta>
      <title-group>
        <article-title>A New Context-Aware Learning System for Predicting Services to Users in Ubiquitous Environment</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Jieun Lee</string-name>
          <email>jieun@gist.ac.kr</email>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Sanghoun Oh</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Moongu Jeon</string-name>
          <email>mgjeon@gist.ac.kr</email>
        </contrib>
      </contrib-group>
      <pub-date>
        <year>2007</year>
      </pub-date>
      <abstract>
        <p>- This paper represents a new context-aware learning system to provide services in ubiquitous computing environment. The aim is to precisely decide which services each user provides. To achieve this goal, we design a preprocessing method (i.e., context modeling) to obtain good information which represents user's characteristics from context-aware information (i.e., user profiles) which consists of states: who, when, where, why, what, and how: 5W1H. The proposed system applies the state-of-the-art naïve Bayesian Decision Theory, which is one of the statistical analyses based on probability theorem.</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>Index Terms — context-aware application, naïve Bayesian
classifier, and user’s preference learner</p>
    </sec>
    <sec id="sec-2">
      <title>I. INTRODUCTION</title>
      <p>Rbeen developing to provide various services to each user in
ECENTLY, many context-aware applications (CAAs) have
ubiquitous computing environment. CAAs help each user
to decide his or her decision as extracting meaningful
information from many kinds of contexts such as locations,
identifications, activities, states of users, and so on. These
services apply most of the real world entertainments such as
health, education, accident, rescue, and shopping.</p>
      <p>To provide more efficient services, most of the CAAs
have tried to employ machine learning (ML) techniques with
learning data. From this integration of context-aware and ML
technologies, we can configure artificial intelligent service
systems.</p>
      <p>
        In this paper, we propose a new context-aware learning
system using a naïve Bayesian classifier which is one of the
most popular ML methods. The main goal of the proposed
system automatically recommends suitable services to each
user. To learn this system, we employ 6 kinds of contexts (i.e.,
user profile: who, when, where, why, what, and how (5W1H))
[
        <xref ref-type="bibr" rid="ref1">1</xref>
        ].
      </p>
      <p>The paper is organized as follows. In section 2, we
introduce the proposed context-aware learning system. The
paper concludes in section 3.</p>
    </sec>
    <sec id="sec-3">
      <title>II. PROPOSED CONTEXT-AWARE LEARNING SYSTEM</title>
      <p>
        This research is the sub-system of user profile management
system which plays a role in managing all data for
personalizing users [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. A proposed context-aware learning
system is to provide high quality services to each user as
automatically learning based on user’s preference. Figure. 1
shows overall procedures of the proposed context-aware
learning system which is classified by two parts: context
modeling and preference learner.
      </p>
      <p>
        First, the context modeling processes context-information
from data collected by many kinds of sensors, time, and user
preference [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ]. Table. 1 describes items and types of user
profiles using in the proposed system.
      </p>
      <p>Table. 1 Data types and values</p>
      <p>
        The second part is preference learner for users. This
process consists of a rule-based engine and a naïve Bayesian
classifier. The rule-based engine generates (Rule Constructor),
saves, and manages rules (Experience) [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ]. Especially, this
engine makes new rules in order to apply some information not
represented by user profile into learning scheme. The primary
role of the naïve Bayesian classifier is to provide the
appropriate services to users using those rules. This
classification system is useful in our learning system based on
user’s preference because naïve Bayesian classifier is the
simplest form of Bayesian networks and is able to easily
calculate probability as assuming whole attributes in
context-information is independent [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. In the proposed system,
whole data are categorized by 6 items considering dependency
between each attribute in the context modeling process;
therefore, these attributes is independent. For example, when
daddy turn a television on in the morning, there is not a
correlation among attributes (i.e., who (Dad) and when
(Morning), or who and what service (TV.on). Therefore, 6
items of context-information are independent in each other.
      </p>
      <p>
        However, there are 3 constraints in the proposed
context-aware learning system. Firstly, we should control the
number of training data due to limitation of resources. Next, we
should prevent needless update because of efficient
computation time. In the above constraint, we divide 3 learning
modes [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ] [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ]: Monitoring mode (Collecting user information),
Control mode (Considering new and changed information), and
Stable mode (Providing services until users satisfy). All of the
modes are classified by reliability which is settled by the
number of training data and variation of rules. Finally, we
define top priorities (emergency, disasters) [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ].
      </p>
    </sec>
    <sec id="sec-4">
      <title>III. CONCLUSIONS</title>
      <p>
        In this paper, we have introduced a context-aware learning
system to recommend services into each user in ubiquitous
environment. The proposed system is divided by two parts: the
context modeling process and the naïve Bayesian classification
process to predict services for extracting high level information
from low level data. In the future, we will apply various
statistical machine learning methods such as advanced naïve
Bayesian methods (e.g., selective Bayesian classifier, a
tree-augmented naïve Bayesian classifier (TAN), etc) and
Bayesian neural networks to improve the performance for
providing highly qualitative services [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ]. Also, in the procedure
of context modeling, we will study correlations among contexts
for the personalization of services.
      </p>
    </sec>
    <sec id="sec-5">
      <title>ACKNOWLEDGMENT</title>
      <p>This research is supported by the UCN Project, the MCI 21st
Century Frontier R&amp;D Program in Korea</p>
    </sec>
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