Young-Il Choi

Electronics and Telecommunications Research Institute, Sŏul, Seoul, South Korea

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Publications (12)1.03 Total impact

  • Source
    Yoo-mi Park · Aekyung Moon · Young-il Choi · Sang-ki Kim · Sangha Kim
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    ABSTRACT: In order to provide context-aware services, context modeling is one of the most important tasks. Ontology has been widely accepted for the context modeling but it brings some overheads in the process of reasoning large-scale and dynamic information. In mobile networks, especially, ontology should be verified to be applicable for Context-aware Services since real-time responsiveness for large scale moving users is highly required to be guaranteed. This paper proposes an efficient context model to overcome the limitation of ontology. For the purpose, we design a conceptual context model and compare the processing time of the context-aware mobile service system implying the three different context modeling approaches ontology, database, and proposed hybrid modeling. As the result of performance evaluations, the proposed hybrid model shows faster processing time among them and lesser affected by the major metrics of mobile services changeability and number of users than the two existing models. Based on the experimental results, we expect that the proposed hybrid model is very useful and efficient for fast responsiveness to support Context-aware Services for large scale users in mobile networks.
    Full-text · Conference Paper · Feb 2010
  • Aekyung Moon · Hyunghwan Kim · Kisoon Sung · Young-il Choi
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    ABSTRACT: Personalization has a key role to play in making a ubiquitous computing system more usable to the end user. Our goal is to provide the end user with two-step personalization services. To do this, we propose the personalized situation model consisted of user behavior and user preferences models. The former is to set up a weighted list of useful services according to user behavior patterns of current situation. The latter is to set up a weighted list of specific contents according to the service selected by a user. That is to say, two-step personalization services are consisted of service recommendation step and contents recommendation step. As a result, if user selected TV service among service categories to be recommended at the first step, it should match a user's desired TV programs and recommend TV programs with high user preference at the second step.
    No preview · Conference Paper · Mar 2009
  • Aekyung Moon · Yoo-Mi Park · Young-Il Choi

    No preview · Conference Paper · Jan 2009
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    ABSTRACT: In ad-hoc networks, mobile nodes cannot be supported the group authentication by Internet infrastructure. To resolve the group authentication in ad-hoc networks, several protocols for group key agreement have been proposed. These protocols assumes the reliable communication links between MNs. However, wireless links in ad-hoc network are inherently unreliable. We propose a group key agreement algorithm based on hyper-cube key agreement scheme to cope with failed links during group key agreement. When a link failure occurs in hyper-cube key agreement scheme, the key agreement keeps up the process no longer. The algorithm deals with any single link failures on any one plane of a hyper-cube.
    No preview · Conference Paper · Jan 2009
  • Aekyung Moon · Young-Il Choi · Byung-Sun Lee
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    ABSTRACT: With the advent of ubiquitous computing environments, a significant amount of work has been devoted to context-aware. We proposed the context-aware user model, which is aware of its userpsilas situation and recommends personalized services based on this information. This paper focuses on how our algorithms can be applied to a variety of environment easily and evolve user model without previously known information since the concerns of privacy. The proposed user model consists of context and action pairs. Using context-aware user model, we learn user behavior pattern in the situation, which is captured by union of contexts according to current environments. In order that our user model applies to new environment, only context profiles are required to be defined without any modification to model. Moreover we evolved user model through interactions between users and mobile devices using learning mechanism. Finally, we evaluate the precision of proposed approach using simulation with data sets of UCI depository.
    No preview · Conference Paper · Nov 2008
  • Source
    Yoo-Mi Park · Jong-Chul Yim · Young-Il Choi · Sang-Ha Kim
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    ABSTRACT: This paper reviews the Parlay X and proposes SIP multimedia session control mechanism which is able to be implemented over IMS using Extended Call Control APIs of Parlay X. Parlay X is one of the industrial standards of Open API in the telecommunication to open network resources and capabilities to third party service providers. In this paper, SIP session control mechanism is described by depicting call flows of basic and essential session handling methods including session initiation, transfer, restoration, and termination. We also show how easy Parlay X Extended Call Control APIs can be used for the purpose of complicated calls handling in the IT applications. To verify feasibility of the blended services based on convergence of telecommunication and internet with regard to performance, we accomplish experimental performance of Extended Call Control APIs from IT application through open service gateway. We show Open API could be applied to next generation network based on IMS without serious degradation of the network performance.
    Full-text · Article · Jan 2008
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    ABSTRACT: Web services utilize a standard communication infrastructure such as XML and SOAP to communicate through the Internet. Even though Web services are becoming more and more widespread as an emerging technology, it is hard to test Web services because they are distributed applications with numerous aspects of runtime behavior that are different from typical applications. This paper presents a new approach to testing Web services based on EFSM (Extended Finite State Machine). WSDL (Web Services Description Language) file alone does not provide dynamic behavior information. This problem can be overcome by augmenting it with a behavior specification of the service. Rather than domain partitioning or perturbation techniques, we choose EFSM because Web services have control flow as well as data flow like communication protocols. By appending this formal model of EFSM to standard WSDL, we can generate a set of test cases which has a better test coverage than other methods. Moreover, a procedure for deriving an EFSM model from WSDL specification is provided to help a service provider augment the EFSM model describing dynamic behaviors of the Web service. To show the efficacy of our approach, we applied our approach to Parlay-X Web services. In this way, we can test Web services with greater confidence in potential fault detection.
    Full-text · Conference Paper · May 2006
  • Source
    Yoo-mi Park · Young-il Choi · Sang-ha Kim
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    ABSTRACT: Open API in telecommunication is a service control technologies and is a set of abstract standard operations which can provide capabilities to access telecom network for the 3rd party service provider in a secure manner. This paper describes presence-based call reservation service which is a case study of converged service with open API on the Web-service architecture in broadband converged network. The presence-based call reservation service could provide the enterprise with combining capabilities of accessing network resources and manipulating enterprise data resources. We also propose a simple control mechanism for realization of this service with open API on the Web-service architecture
    Full-text · Conference Paper · Mar 2006
  • Jong-choul Yim · Young-il Choi · Byung-sun Lee
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    ABSTRACT: One of the key factors of next generation networks (NGN) is opening up the capabilities of the network. Parlay Group leads the standard, so called Parlay/OSA API, to open up the networks by defining, establishing, and supporting a common industry-standard APIs. Parlay Group also specifies the Parlay Web services API, also known as Parlay X API, which is much simpler than Parlay/OSA API to enable IT developers to use it without network expertise. One of Parlay X API is third party call (TPC) API which provides simple API for the purpose of creating and managing the call by the third party. IMS was devised originally by 3GPP for mobile networks, but currently it is accepted widely as a reference model of NGN even in fixed network domains. IMS has an interface called ISC to open the network capabilities. This paper overviews how Parlay X Web services can be supported in IMS in an architectural perspective, and discusses how the third party call can be implemented in IMS using Parlay X TPC APIs
    No preview · Conference Paper · Mar 2006
  • Jin-Ok Hwang · Sung-Gi Min · Young-Il Choi
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    ABSTRACT: Configuring IP addresses is an important issue in ad-hoc networks without a centralized agent server. The previous configuration methods result in wasted IP addresses, and are unsuitable for assigning addresses in small-scale mobile Ad-Hoc networks (MANET). To address this problem, we propose a tightly packed IP address (TPIA) configuration protocol, which eliminates the IP address leaks characteristic of current addressing methods (Internet Protocol version 4, or IPv4).
    No preview · Conference Paper · Jan 2006
  • JinHo Ahn · Sung-Gi Min · Young-Il Choi · Byung-Sun Lee
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    ABSTRACT: Distributed hierarchical network monitoring model has been proposed to solve scalability problem of centralized model. In this distributed model, a top-level monitoring manager, called main manager, obtains aggregate management information from mid-level managers, named domain managers, forming a hierarchical structure. However, if some of monitoring managers crash, network elements cannot be continuously and correctly monitored until the managers are repaired. To address this important, but previously unresolved issue, this paper presents a new fault-tolerance protocol for domain managers, named DMFTP, allowing the managers to efficiently utilize their organization structure. Therefore, this protocol can minimize failure detection overhead and the number of live managers affected by each manager node crash. Also, it tolerates concurrent manager failures and, after the failed managers have been repaired, ensures their immediate and consistent recovery.
    No preview · Conference Paper · Jan 2003
  • Ho-Jin Park · Young-Il Choi · Byung-Sun Lee · Kyung Pyo Jun
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    ABSTRACT: To meet the rigorous demands of today’s fast-moving telecommunication environment, every carriers want to deploy new services smoothly with minimal impact on the underlying infrastructure. Also it is necessary to create an open environment that enables the deployment of multivendor switching systems with optimum functionality and performance. The MSF(Multiservice Switching Forum) is an industrial forum to develop the network infrastructure that meets the above requirements. The MSF has been focusing on reaching and promoting consensus on the implementation of MSS(Multiservice Switching System) that realizes the vision of multiservice switching and defines a set of open intra-switching system interfaces. In this paper, we review the system architecture and characteristics of the MSS based on MSF architecture. We propose the open software architecture for the implementation of the MSS, the control scenarios for ATM SVC(Switched virtual Connection) service and management functions in the software architecture. The environment for software development is also considered.
    No preview · Conference Paper · Jan 2001